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Eicosanoids in Inflammation: Biosynthesis, Pharmacology, and Therapeutic Frontiers
Abstract
In mammalian cells, eicosanoid biosynthesis is usually initiated by the activation of phospholipase A2 and the release of arachidonic acid (AA) from membrane phospholipids. The AA is subsequently transformed by cyclooxygenase (COX) and lipoxygenase (LO) pathways to prostaglandins, thromboxane and leukotrienes collectively termed eicosanoids. Eicosanoid production is considerably increased during inflammation. Both COX and LO pathways are of particular clinical relevance. The COX pathway is the major target for non-steroidal anti-inflammatory drugs (NSAIDs), the most popular medications used to treat pain, fever and inflammation. Although their anti-inflammatory effects are well known, their long-term use is associated with gastrointestinal (GI) complications such as ulceration. In 1991, it was discovered that COX exists in two distinct isozymes, COX-1 and COX-2, of which COX-2 is primarily expressed at sites of inflammation and produces pro-inflammatory eicosanoids. For this reason, COX-2 selective inhibitors (COXIBs) have been developed recently as anti-inflammatory agents to minimize the risk of GI toxicity. Recently, some COX-2 selective inhibitors have shown adverse cardiovascular side effects, resulting in the withdrawal of rofecoxib and valdecoxib from the market. Selective inhibition of COX-2 without reducing COX-1-mediated thromboxane production could alter the balance between prostacyclin and thromboxane and promote a prothrombotic state, thereby explaining the observed COX-2 cardiovascular risk. In this review, we describe mechanisms for the production of pro-inflammatory eicosanoid mediators contributing to inflammation and summarize promising options for the prevention of inflammatory mediator formation and the therapeutic inhibition of pain and inflammation.
... Eicosanoids are a family of fatty acid metabolites generated from 20-carbon polyunsaturated fatty acids (PUFAs) synthesized by enzymatic oxygenation pathways involving a distinct family of enzymes, the oxygenases (Khanapure et al., 2007). Eicosanoids are not stored, but promptly synthesized de novo after cell activation (Bozza et al., 2011) through a highly regulated event, primarily involving three oxygenases: cyclooxygenases (COXs), P450 cytochrome epoxygenases (CYP450), and lipoxygenases (LOXs) (Alvarez and Lorenzetti, 2021). ...
... PGE 2 has vasodilation effects and increases the permeability of postcapillary venules, early events in the inflammatory response (Funk, 2001) (Figure 3). Furthermore, PGs may synergize in the blood vessel with other pro-inflammatory mediators, such as histamine or bradykinin, to increase vascular permeability and promote edema (Funk, 2001;Khanapure et al., 2007). ...
Polyunsaturated fatty acids (PUFAs) are structural components of membrane phospholipids in cells. PUFAs regulate cellular function through the formation of derived lipid mediators termed eicosanoids. The oxygenation of 20-carbon PUFAs via the oxygenases cyclooxygenases, lipoxygenases, or cytochrome P450, generates a class of classical eicosanoids including prostaglandins, thromboxanes and leukotrienes, and also the more recently identified hydroxy-, hydroperoxy-, epoxy- and oxo-eicosanoids, and the specialized pro-resolving (lipid) mediators. These eicosanoids play a critical role in the regulation of inflammation in the blood and the vessel. While arachidonic acid-derived eicosanoids are extensively studied due to their pro-inflammatory effects and therefore involvement in the pathogenesis of inflammatory diseases such as atherosclerosis, diabetes mellitus, hypertension, and the coronavirus disease 2019; in recent years, several eicosanoids have been reported to attenuate exacerbated inflammatory responses and participate in the resolution of inflammation. This review focused on elucidating the biosynthesis and the mechanistic signaling of eicosanoids in inflammation, as well as the pro-inflammatory and anti-inflammatory effects of these eicosanoids in the blood and the vascular wall.
... This interdependence of IL-23 and COX-derived metabolites suggests the existence of multiple converging signaling pathways that synergistically potentiate peripheral and central sensitization mechanisms. The role of COX-generated eicosanoids in nociception is well documented, with prostaglandins (especially PGE 2 ) being key contributors to nociceptor sensitization by reducing their activation threshold and elevating pain perception [120,121]. ...
Interleukin-23 is crucial in the initiation and progression of certain inflammatory disorders. As a key cytokine, IL-23 is involved in the differentiation and activation of Th17 cells, which play a role in a broad spectrum of inflammatory diseases. This review examines the molecular mechanisms through which IL-23 contributes to the pathogenesis of conditions including psoriasis, rheumatoid arthritis, inflammatory bowel disease, and multiple sclerosis. By elucidating the significant role of IL-23 in inflammation, this review underscores its importance as a therapeutic target for managing inflammatory conditions, with particular emphasis on current and emerging biologic treatments.
... In patients with paroxysmal or persistent AF, NOX2 upregulation leads to increased production of isoprostanes, which are eicosanoids involved in cardiac inflammation and immunity. However, this upregulation is not observed in permanent AF, indicating a potential difference in the inflammatory pathways involved [10,11]. ...
Atrial fibrillation (AF) can present as persistent or permanent forms with each exhibiting distinct pathological features. This study explores the gene signatures associated with cardiac and immune cells in persistent and permanent AF compared to sinus rhythm controls. We performed a meta-analysis to combine independent microarray and RNA sequencing (RNAseq) datasets for both persistent and permanent AF left atrial tissue. Cell type abundances were inferred using Cibersort and CibersortX, and gene set enrichment analysis was performed using ShinyGo. In persistent AF, a significant reduction in atrial cardiomyocytes and smooth muscle cells, along with an increase in fibroblasts, myeloid cells and pericytes was observed. Permanent AF showed increased endothelial cell and pericyte abundance. Immune cell analysis revealed altered abundances in five cell types in persistent AF, particularly an increase in neutrophils, which was not observed in permanent AF. Pathway analysis identified enriched neutrophil activation and degranulation in persistent AF, while permanent AF was enriched in extracellular matrix organization and angiogenesis pathways. In conclusion, this study highlights distinct and complex immune and cellular dynamics between chronic AF, where persistent AF has heightened immune cell infiltration and neutrophil activity which contribute to sustaining AF, whereas permanent AF shows inflammation returning to baseline but enhanced tissue remodelling and angiogenesis.
... Arachidonic acid, stored in cell membrane phospholipids, is converted via cyclooxygenase (COX) and lipoxygenase (LO) pathways into prostaglandins, thromboxane, and leukotrienes. These eicosanoids see a significant synthesis increase during inflammation, correlating with the inflammatory response to infection, allergy, or injury (Boyce 2008;Khanapure et al. 2007). ...
Inflammation is a necessary immunological response that promotes survival and preserves tissue homeostasis, a common characteristic linked to various diseases. However, in some circumstances, the inflammatory response is deleterious and contributes to disease pathogenesis. Anti-inflammatory substances have poor affinity for inflamed tissues, resulting in low concentrations in the target tissue and a higher incidence of severe adverse effects. To address this issue, several potential approaches have been proposed, such as chemical modification of drug molecules and the development of nanocarriers for drug delivery. Since the development of nanotechnology at the beginning of the twenty-first century, researchers have been using the pathophysiological characteristics of inflammation, primarily leaky vasculature, and biomarker overexpression to develop nanomedicines that can deliver therapeutics via passive and active targeting mechanisms to sites of inflammation and produce therapeutic effects. Drug carriers based on nanoparticles can enhance the safety and efficacy of drugs by increasing their capacity, enhancing their solubility, combining several drugs, protecting them from metabolism, and regulating their release. An approach that shows promise in the treatment of various inflammatory diseases is the application of nanomedicines. Nanomedicine involves nanoparticles that have been loaded with a therapeutically active component. Nanomedicines can target inflammation by recognizing molecules highly expressed on endothelial cells or activated macrophage surfaces, enhancing the permeability of vessels, or even by biomimicry. A review of the research findings shows significant potential for the use of nanotechnology to enhance the quality of life for people using NSAIDs for chronic disorders by minimizing drug side effects or the duration of administration. After a brief introduction to inflammation, its various forms- acute and chronic inflammation, and the pathophysiology of inflammation, this review highlights the main innovative nanocarriers utilized for carrying various nonsteroidal anti-inflammatory drugs that have been utilized in treating various inflammatory disorders.
... An increase in the PGE 2 level was detected in human pulps diagnosed as having reversible pulpitis (55). Eicosanoids are thought to essentially exacerbate inflammation, and the cyclooxygenase pathway involved in eicosanoid production is a major target for nonsteroidal antiinflammatory drugs (NSAIDs) (56). Recently, the potential of these eicosanoids to induce the healing of pulpitis, including hard tissue induction, has been a focus for research. ...
Dental pulp is a mesenchymal connective tissue located inside the rigid encasement of the dentin. When bacteria or bacterial products invade the dental pulp, inflammation known as pulpitis is induced in this tissue. Various mediators produced during the course of pulpitis profoundly modify the pathophysiology of the inflammation. Typical mediators include cytokines, chemokines, nitric oxide, reactive oxygen species, matrix metalloproteinases, proteases, neutrophil extracellular traps, neuropeptides, and eicosanoids. Controlling these mediators may potentially lead to the healing of pulpitis and the preservation of pulp tissue. This review discusses these mediators and further explores the possibility of controlling them.
... PUFAs, such as omega-3 and omega-6 FAs, are enzymatically and non-enzymatically oxygenated into oxylipins, a diverse class of non-structural, soluble lipid mediators. The enzymatic production of oxylipins is catalyzed mainly by lipoxygenase, cyclooxygenase, and cytochrome P450 families 9,10 . PUFA substrates for lipid mediator synthesis are obtained either through de novo production following repetitive elongation and desaturation steps or from host secretions rich in unsaturated C16 and C18 lipids 4,5,9,11 . ...
Sebaceous free fatty acids are metabolized by multiple skin microbes into bioactive lipid mediators termed oxylipins. This study investigated correlations between skin oxylipins and microbes on the superficial skin of pre-pubescent children (N = 36) and adults (N = 100), including pre- (N = 25) and post-menopausal females (N = 25). Lipidomics and metagenomics revealed that Malassezia restricta positively correlated with the oxylipin 9,10-DiHOME on adult skin and negatively correlated with its precursor, 9,10-EpOME, on pre-pubescent skin. Co-culturing Malassezia with keratinocytes demonstrated a link between 9,10-DiHOME and pro-inflammatory cytokines IL-1β and IL-6 production. We also observed strong correlations between other skin oxylipins and microbial taxa, highlighting life stage differences in sebum production and microbial community composition. Our findings imply a complex host-microbe communication system mediated by lipid metabolism occurring on human skin, warranting further research into its role in skin health and disease and paving the way towards novel therapeutic targets and treatments.
... They have been recognized as important signaling molecules that are not stored but are synthesized de novo in response to cell activation [37]. Eicosanoids are generated from PUFAs by enzymatic oxygenation pathways involving a distinct family of enzymes: the oxygenases [38]. Precursors and enzymes involved in this synthesis are localized at lipid droplets [37]. ...
Polyunsaturated fatty acids (PUFAs) are not only structural components of membrane phospholipids and energy storage molecules in cells. PUFAs are important factors that regulate various biological functions, including inflammation, oxidation, and immunity. Both n-3 and n-6 PUFAs from cell membranes can be metabolized into pro-inflammatory and anti-inflammatory metabolites that, in turn, influence cardiovascular health in humans. The role that PUFAs play in organisms depends primarily on their structure, quantity, and the availability of enzymes responsible for their metabolism. n-3 PUFAs, such as eicosapentaenoic (EPA) and docosahexaenoic (DHA), are generally known for anti-inflammatory and atheroprotective properties. On the other hand, n-6 FAs, such as arachidonic acid (AA), are precursors of lipid mediators that display mostly pro-inflammatory properties and may attenuate the efficacy of n-3 by competition for the same enzymes. However, a completely different light on the role of PUFAs was shed due to studies on the influence of PUFAs on new-onset atrial fibrillation. This review analyzes the role of PUFAs and PUFA derivatives in health-related effects, considering both confirmed benefits and newly arising controversies.
... LA is a dietary essential FA, whereas AA is considered conditionally essential, since it can be made from the former, and its presence in the diet is not essential for life. Therefore, a suitable intake of these FA in diet is necessary, while high amounts are involved in the synthesis of inflammatory eicosanoids (Khanapure et al., 2007). In addition, among other n-6 PUFA, we found that 20:2n-6 and 20:3n-6 as longchain FA, associated with a lower PC risk. ...
Pancreatic cancer (PC) is one of the most fatal malignancies, which has attracted scientists to investigate its etiology and pathogenesis. Nevertheless, the association between erythrocyte fatty acids and PC risk remains unclear. This study aimed to evaluate the association between levels of erythrocyte fatty acids and PC risk. The erythrocyte fatty acid compositions of 105 PC patients and 120 controls were determined by gas chromatography. Cases and controls were frequency matched by age and sex. Multivariable conditional logistic regression model and restricted cubic spline were applied to estimate the odds ratio with 95% confidence interval (OR, 95% CI) of erythrocyte fatty acids and PC risk. Our main findings indicated a significant negative association between levels of erythrocyte total monounsaturated fatty acids (MUFA) and n‐3 polyunsaturated fatty acids (n‐3 PUFA) and the risk of PC (OR T3‐T1 = 0.30 [0.14, 0.63] and OR T3‐T1 = 0.15 [0.06, 0.33], respectively). In contrast, erythrocyte n‐6 polyunsaturated fatty acids, specifically linoleic acid (LA) and arachidonic acid (AA) levels, were positively associated with PC incidence (R T1‐T3 = 4.24 [1.97, 9.46] and OR T1‐T3 = 4.53 [2.09, 10.20]). Total saturated fatty acid (SFA), especially high levels of palmitic acid (16:0), was positively associated with the risk of PC (OR T3‐T1 = 3.25 [1.53, 7.08]). Our findings suggest that levels of different types of fatty acids in erythrocytes may significantly alter PC susceptibility. Protective factors against PC include unsaturated fatty acids such as n‐3 PUFA and MUFA.
... Both primarily cause redness and oedema by increasing arterial dilation and microvascular permeability alongside other inflammatory vasodilators (Ricciotti and Fitzgerald, 2011). It is believed that PGE2 and PGI2 also induce pain in the inflamed site by sensitizing the free ends of peripheral nervous system neurons (Khanapure et al., 2007). Many anti-inflammatory herbal extracts have been found to act on COX-2, which is closely associated with inflammatory disorders of acute and chronic states (Nworu and Akah, 2015). ...
Inflammation is defined as a defensive response of the body against invading agents and harmful stimuli directly involved in the pathophysiology of various chronic diseases. Conventional anti-inflammatories have always been the first choice to treat and control inflammation and inflammation-related diseases. However, researchers have been searching for safer alternatives to conventional drugs with fewer possible side effects. Medicinal plants are considered potent alternatives to these drugs. Thus, understanding the molecular mechanisms of these plants and their biological targets can provide a new prospect for developing new anti-inflammatory agents with safer effects. Vitex trifolia belongs to the family Verbenaceae, a multipurpose medicinal plant, which can exhibit anti-inflammatory property. In recent literature, the plant was reported to have significant anti-inflammatory actions, including inhibitory effects on pro-inflammatory signaling pathways and mediators. Herein, the molecular anti-inflammatory effects of Vitex trifolia and its active components during inflammation have been reviewed.
... Specifically, lipid mediators are generated either through spontaneous non-enzymatic free-radical-catalyzed or highly regulated enzymatic oxygenation of omega-3 (n-3) or omega-6 (n-6) PUFA. The enzymatic reactions are facilitated mainly by lipoxygenases (LOX), cyclooxygenases (COX), or via pathways involving epoxygenases of the cytochrome P450 family [58]. ...
Effects of pre- and probiotics on intestinal health are well researched and microbiome-targeting solutions are commercially available. Even though a trend to appreciate the presence of certain microbes on the skin is seeing an increase in momentum, our understanding is limited as to whether the utilization of skin-resident microbes for beneficial effects holds the same potential as the targeted manipulation of the gut microflora. Here, we present a selection of molecular mechanisms of cross-communication between human skin and the skin microbial community and the impact of these interactions on the host’s cutaneous health with implications for the development of skin cosmetic and therapeutic solutions. Malassezia yeasts, as the main fungal representatives of the skin microfloral community, interact with the human host skin via lipid mediators, of which several are characterized by exhibiting potent anti-inflammatory activities. This review therefore puts a spotlight on Malassezia and provides a comprehensive overview of the current state of knowledge about these fungal-derived lipid mediators and their capability to reduce aesthetical and sensory burdens, such as redness and itching, commonly associated with inflammatory skin conditions. Finally, several examples of current skin microbiome-based interventions for cosmetic solutions are discussed, and models are presented for the use of skin-resident microbes as endogenous bio-manufacturing platforms for the in situ supplementation of the skin with beneficial metabolites.
... As any other drug, the antiinflammatory drugs display many side-effects which range from gastrointestinal irritation, ulcers to hypertension and cardiac abnormalities [8,9]. Many intermediary mediators such as PGE2, LTB4 play a role in the COX and LOX pathways and thus can be the potential target to prevent inflammation [10]. Hence, herbal sourced products are more reliable and cause fewer side effects to those of manufactured drugs. ...
... We decided to study the role of the secreted Phospholipase A2 Group IID (Pla2g2d) on IL-13enhanced SARS2-N501YMA30 disease for three main reasons: 1) phospholipase abundance is the first and a rate-limiting step in eicosanoid function (39), 2) Pla2g2d was the top phospholipase . CC-BY-NC-ND 4.0 International license available under a was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. ...
Treatments available to prevent progression of virus-induced lung diseases, including coronavirus disease 2019 (COVID-19) are of limited benefit once respiratory failure occurs. The efficacy of approved and emerging cytokine signaling-modulating antibodies is variable and is affected by disease course and patient-specific inflammation patterns. Therefore, understanding the role of inflammation on the viral infectious cycle is critical for effective use of cytokine-modulating agents. We investigated the role of the type 2 cytokine IL-13 on SARS-CoV-2 binding/entry, replication, and host response in primary HAE cells in vitro and in a model of mouse-adapted SARS-CoV-2 infection in vivo. IL-13 protected airway epithelial cells from SARS-CoV-2 infection in vitro by decreasing the abundance of ACE2- expressing ciliated cells rather than by neutralization in the airway surface liquid or by interferon-mediated antiviral effects. In contrast, IL-13 worsened disease severity in mice; the effects were mediated by eicosanoid signaling and were abolished in mice deficient in the phospholipase A2 enzyme PLA2G2D. We conclude that IL-13-induced inflammation differentially affects multiple steps of COVID-19 pathogenesis. IL-13-induced inflammation may be protective against initial SARS-CoV-2 airway epithelial infection; however, it enhances disease progression in vivo. Blockade of IL-13 and/or eicosanoid signaling may be protective against progression to severe respiratory virus-induced lung disease.
RESEARCH IN CONTEXT
Evidence before this study
Prior to this study, various pieces of evidence indicated the significant role of cytokines in the pathogenesis and progression of COVID-19. Severe COVID-19 cases were marked by cytokine storm syndrome, leading to immune activation and hyperinflammation. Treatments aimed at modulating cytokine signaling, such as IL-6 receptor antagonists, had shown moderate effects in managing severe COVID-19 cases. Studies also revealed an excessive production of type 2 cytokines, particularly IL-13 and IL-4, in the plasma and lungs of COVID-19 patients, which was associated with adverse outcomes. Treatment with anti-IL-13 monoclonal antibodies improved survival following SARS-CoV-2 infection, suggesting that IL-13 plays a role in disease severity. Type 2 cytokines were observed to potentially suppress type 1 responses, essential for viral clearance, and imbalances between these cytokine types were linked to negative COVID-19 outcomes. These findings highlighted the complex interactions between cytokines and the immune response during viral infections, underscoring the importance of understanding IL-13’s role in COVID-19 and related lung diseases for developing effective therapeutic interventions.
Added value of this study
In this study, we explored the impact of IL-13-induced inflammation on various stages of the SARS-CoV-2 infection cycle using both murine (in vivo) and primary human airway epithelial (in vitro) culture models. Our findings indicated that IL-13 provided protection to airway epithelial cells against SARS-CoV-2 infection in vitro, partly by reducing the number of ACE2- expressing ciliated cells. Conversely, IL-13 exacerbated the severity of SARS2-N501Y MA30 -induced disease in mice, primarily through Pla2g2d-mediated eicosanoid biosynthesis.
Implications of the available evidence
Current evidence indicates that PLA 2 G2D plays a crucial role in the IL-13-driven exacerbation of COVID-19 in mice, suggesting that targeting the IL-13-PLA2G2D axis could help protect against SARS-CoV-2 infection. These insights are important for clinical research, especially for studies focusing on drugs that modify IL-13 signaling or modulate eicosanoids in the treatment of asthma and respiratory virus-induced lung diseases.
... Eicosanoids are arachidonic acid (AA)-derived lipids that represent the most prominent genus among bioactive lipids, and those that have been studied the most thus far, as the main therapeutic target of all cyclooxygenase 1 and 2 (COX1-2)-inhibiting nonsteroidal anti-inflammatory drugs (NSAID) [96]. All eicosanoids are produced when AA that is tethered to membrane glycerophospholipids is released upon the activation of phospholipase A2 (PLA2), before undergoing the COX1/2-dependent oxidation that leads to prostaglandins and thromboxanes or being targeted by lipoxigenases (LOX) in a pathway that leads to leukotriene biosynthesis [97]. ...
The present review provides a comprehensive examination of the intricate dynamics between α-synuclein, a protein crucially involved in the pathogenesis of several neurodegenerative diseases, including Parkinson’s disease and multiple system atrophy, and endogenously-produced bioactive lipids, which play a pivotal role in neuroinflammation and neurodegeneration. The interaction of α-synuclein with bioactive lipids is emerging as a critical factor in the development and progression of neurodegenerative and neuroinflammatory diseases, offering new insights into disease mechanisms and novel perspectives in the identification of potential biomarkers and therapeutic targets. We delve into the molecular pathways through which α-synuclein interacts with biological membranes and bioactive lipids, influencing the aggregation of α-synuclein and triggering neuroinflammatory responses, highlighting the potential of bioactive lipids as biomarkers for early disease detection and progression monitoring. Moreover, we explore innovative therapeutic strategies aimed at modulating the interaction between α-synuclein and bioactive lipids, including the development of small molecules and nutritional interventions. Finally, the review addresses the significance of the gut-to-brain axis in mediating the effects of bioactive lipids on α-synuclein pathology and discusses the role of altered gut lipid metabolism and microbiota composition in neuroinflammation and neurodegeneration. The present review aims to underscore the potential of targeting α-synuclein-lipid interactions as a multifaceted approach for the detection and treatment of neurodegenerative and neuroinflammatory diseases.
... Many studies have reported the effects of NSAIDs in different experimental epilepsy models (Table 1). Although their anti-inflammatory effects are well known, their long-term use is associated with gastrointestinal complications, such as ulceration [89]. What's more, although many of these drugs have shown good anticonvulsant effects in epilepsy animal models, their effects are numerous and complex, and have yet to be fully evaluated. ...
Arachidonic acid (AA), an important polyunsaturated fatty acid in the brain, is hydrolyzed by a direct action of phospholipase A2 (PLA2) or through the combined action of phospholipase C and diacylglycerol lipase, and released into the cytoplasm. Various derivatives of AA can be synthesized mainly through the cyclooxygenase (COX), lipoxygenase (LOX) and cytochrome P450 (P450) enzyme pathways. AA and its metabolic enzymes and metabolites play important roles in a variety of neurophysiological activities. The abnormal metabolites and their catalytic enzymes in the AA cascade are related to the pathogenesis of various central nervous system (CNS) diseases, including epilepsy. Here, we systematically reviewed literatures in PubMed about the latest randomized controlled trials, animal studies and clinical studies concerning the known features of AA, its metabolic enzymes and metabolites, and their roles in epilepsy. The exclusion criteria include non-original studies and articles not in English.
... Therefore, ensuring suitable dietary intake of these FAs is crucial, as excessive amounts have been implicated in the pro-inflammatory and prothrombotic actions. 42 Specifically, excess C20:4n-6 is proven to be metabolized by lipoxygenases and cyclooxygenases into pro-inflammatory eicosanoids. 31 Indeed, a recent investigation evaluating the association between dietary fat consumption and CVD in the Chinese population across 30 years revealed a significant increase in the proportion of n-6 PUFAs in the Chinese diet (32.8% to 40.9%). ...
Background & aims: There is limited and conflicting evidence about the association of erythrocyte fatty acids with coronary artery disease (CAD), particularly in China where the CAD rates are high....
... Regrettablymaximumnumber of the anti-inflammatory drugs, predominantly steroids and COX inhibitors are frequently accompanying with adverse side effects including, gastrointestinal irritation, hypertension, ulcers and cardiac abnormalities (William, 1989;Wolfe et al, 1999). PGE 2 and LTB 4 are the key inflammatory mediators derived from the arachidonic acid metabolism through COX and LOX pathways of mammal's cell membrane (Khanapure et al, 2007). PGE 2 and LTB 4 are involved in modulating the intensity of inflammatory responses, and also have number of proinflammatory effects, including increasing vascular permeability, vasodilation, enhances local blood flow and local pyrexia and potentiation of pain caused by other agents. ...
... Many intermediary mediators such as PGE 2 , LTB 4 play a role in the COX and LOX pathways and thus can be the potential target to prevent inflammation [10]. Hence, herbal sourced products are more reliable and cause fewer side effects to those of manufactured drugs. ...
The research is expected to assess the effect of Annona Reticulata Methanolic leaves Extract (ARME) on progression of adjuvant induced arthritis in Wistar rats. ARME was obtained through bioactivity guided fraction by 5-Lipooxygenase inhibitory activity. ARME was administrated at 100 and 200mg/kg body weight via oral route for a period of 35 days to the experimental models. On day 8, via a single intra-plantar injection of 0.1mL suspension of heat killed Mycobacterium tuberculosis (100μg/animal) Arthritis was induced, in incomplete Freund’s adjuvant of left foot pads of Wistar rats (female). The paw volume was observed by recording the hematological and biochemical parameters, hind limb paw volume, pathological and radiography changes to evaluate the effect of the extract. On day 35, levels of pro-inflammatory cytokines (TNF-a, IL-1Β) and inflammatory mediators (PGE2, LTB4) was measured in serum samples. On the day of sacrifice, the liver was collected to record the stabilizing ability of lipid peroxide, activities of enzymatic antioxidants catalase, Superoxide Dismutase (SOD) and non-enzymatic antioxidants reduced glutathione (GSH) levels. ARME treated groups; 100 and 200mg/kg and prednisolone 10mg/kg significantly decreased hind paw volume, reduced serum levels of TNF-a, IL-1Β, PGE2 and LTB4, reduced MDA levels and increased levels of catalase, SOD and GSH in the liver. The promising results of serum biochemistry, haematology, histopathology and radiographic changes suggest that the administration of ARME was able to effectively modulate the inflammatory response and conquer the advancement of arthritis in the experimental animal model. Results obtained from the acute oral toxicity limit test establish that ARME (LD50>2000mg/kg) was safe in accordance to the OECD guideline 423. These findings may help to overcome some hurdles in the treatment of rheumatoid arthritis.
... Lipid mediators are a diverse class of lipids derived from non-enzymatic and/or enzymatic oxygenation of long-chain polyunsaturated omega-3 or omega-6 FAs (PUFA). The enzymatic reactions are catalysed mainly by lipoxygenases, cyclooxygenases, and epoxygenases of the cytochrome P450 family (21). The PUFA substrates for lipid mediator synthesis are obtained either through de novo production following repetitive elongation and desaturation steps or from dietary intake. ...
While research into gut-microbe interactions is common and advanced, with multiple defined impacts on human health, studies exploring the significance of skin-microbe interactions remain underrepresented. Skin is the largest human organ, has a vast surface area, and is inhabited by a plethora of microorganisms which metabolise sebaceous lipids. Sebaceous free fatty acids are metabolized into bioactive lipid mediators with immune-modulatory properties by skin-resident microbes, including Malassezia. Intriguingly, many of the same lipid mediators are also found on human skin, implying these compounds may have microbial or mixed microbial/human origin. To support this hypothesis, we isolated lipids and microbial DNA from the skin of prepubescent, adult, pre- and post-menopausal volunteers and performed correlational analyses using skin lipidomics and metagenomics to compare lipid mediator profiles and microbiome compositions on skin with either low or high sebaceous gland activity. We found that specific microbial taxonomies were positively and negatively correlated with skin lipid mediator species with high statistical significance. 2D in vitro co-cultures with Malassezia and keratinocytes also directly linked the production of specific lipid mediators, detected on healthy human skin, to secretion of immuno-stimulatory cytokines. Together, these findings further support the hypothesis that microbial-derived skin lipid mediators influence healthy skin homeostasis and skin disease development and progression, thereby spotlighting the relevance of the skin microbiome footprint on human health.
... Corticosteroids like hydrocortisone reduce the production of these pro-inflammatory eicosanoids, diminishing their impact on the inflammatory cascade. By doing so, hydrocortisone helps prevent excessive vasodilation, increased vascular permeability, and tissue edema associated with uncontrolled eicosanoid release [47]. ...
Sepsis remains a formidable challenge in critical care medicine, often culminating in a life-threatening condition known as septic shock. This review article navigates the intricate landscape of hydrocortisone administration in septic shock management, delving into historical perspectives, current evidence, controversies, mechanisms of action, practical considerations, and the importance of precision medicine. Hydrocortisone's role as an adjunctive therapy is explored, highlighting its potential to stabilize hemodynamics, mitigate the inflammatory response, and improve patient outcomes. However, debates persist regarding patient selection, dosing regimens, safety profiles, and long-term consequences. The future of septic shock management lies in emerging therapies, precision medicine approaches, biomarker discovery, and targeted interventions. Moving forward, exploring novel therapeutic avenues, understanding patient-specific responses, and uncovering potential biomarkers will be crucial in advancing septic shock treatment strategies. Clinical guidelines provide a foundation, but individualized patient care, interdisciplinary collaboration, and ongoing research are essential to optimize treatment strategies. This article underscores the call for continued research and evidence-based practice as we strive to enhance the care of septic shock patients and pursue improved outcomes in this critical condition. Embracing future developments in the field will enable us to adapt and refine our approach, ultimately contributing to the advancement of septic shock management.
... AA is a polyunsaturated 20-carbon fatty acid metabolized by either the cyclooxygenase (COX) or the lipoxygenase (LO) pathways to generate powerful inflammatory mediators called eicosanoids, which comprise prostaglandins, thromboxanes and leukotrienes. Eicosanoids serve as autocrine/paracrine regulators of inflammation and modulate cancer-associated physiopathological responses, including suppression of immune surveillance and enhanced proliferation and invasiveness of tumor cells (14). ...
Colorectal cancer (CRC) is one of the most common and fatal types of cancer. Inflammation promotes CRC development, however, the underlying etiological factors are unknown. Human cytomegalovirus (HCMV), a virus that induces inflammation and other cancer hallmarks, has been detected in several types of malignancy, including CRC. The present study investigated whether HCMV infection was associated with expression of the pro‑inflammatory enzymes 5‑lipoxygenase (5‑LO) and cyclooxygenase‑2 (COX‑2) and other molecular, genetic and clinicopathological CRC features. The present study assessed 146 individual paraffin‑embedded CRC tissue microarray (TMA) cores already characterized for TP53 and KRAS mutations, microsatellite instability (MSI) status, Ki‑67 index and EGFR by immunohistochemistry (IHC). The cores were further analyzed by IHC for the expression of two HCMV proteins (Immediate Early, IE and pp65) and the inflammatory markers 5‑LO and COX‑2. The CRC cell lines Caco‑2 and LS‑174T were infected with HCMV strain VR1814, treated with antiviral drug ganciclovir (GCV) and/or anti‑inflammatory drug celecoxib (CCX) and analyzed by reverse transcription‑quantitative PCR and immunofluorescence for 5‑LO, COX‑2, IE and pp65 transcripts and proteins. HCMV IE and pp65 proteins were detected in ~90% of the CRC cases tested; this was correlated with COX‑2, 5‑LO and KI‑67 expression, but not with EGFR immunostaining, TP53 and KRAS mutations or MSI status. In vitro, HCMV infection upregulated 5‑LO and COX‑2 transcript and proteins in both Caco‑2 and LS‑174T cells and enhanced cell proliferation as determined by MTT assay. Treatment with GCV and CCX significantly decreased the transcript levels of COX‑2, 5‑LO, HCMV IE and pp65 in infected cells. HCMV was widely expressed in CRC and may promote inflammation and serve as a potential new target for CRC therapy.
... E icosanoids and related oxylipins, hereafter referred to as eicosanoids, are small polar lipid compounds produced via the extensive oxidation of mostly 18-to 22-carbon polyunsaturated fatty acids (PUFAs) [1][2][3] . By signaling through cognate receptors, these molecules play key autocrine, paracrine, and endocrine roles across a range of physiological processes, including inflammation, immune activation, thrombosis, and regulation of vascular tone. ...
Eicosanoids are biologically active derivatives of polyunsaturated fatty acids with broad relevance to health and disease. We report a genome-wide association study in 8406 participants of the Atherosclerosis Risk in Communities Study, identifying 41 loci associated with 92 eicosanoids and related metabolites. These findings highlight loci required for eicosanoid biosynthesis, including FADS1-3, ELOVL2, and numerous CYP450 loci. In addition, significant associations implicate a range of non-oxidative lipid metabolic processes in eicosanoid regulation, including at PKD2L1/SCD and several loci involved in fatty acyl-CoA metabolism. Further, our findings highlight select clearance mechanisms, for example, through the hepatic transporter encoded by SLCO1B1. Finally, we identify eicosanoids associated with aspirin and non-steroidal anti-inflammatory drug use and demonstrate the substantial impact of genetic variants even for medication-associated eicosanoids. These findings shed light on both known and unknown aspects of eicosanoid metabolism and motivate interest in several gene-eicosanoid associations as potential functional participants in human disease.
... Dual COX-2/5-LO inhibition may prevent the upregulation of the respective opposed signaling pathway by blocking both targets. Consequently, balanced COX-2/5-LO inhibition may lower the risk for the appearance of severe adverse effects, such as GI injury and hypersensitive reactions [21,38,[41][42][43][44]. ...
Targeting inflammatory mediators and related signaling pathways may offer a rational strategy for the treatment of cancer. The incorporation of metabolically stable, sterically demanding, and hydrophobic carboranes in dual cycloxygenase-2 (COX-2)/5-lipoxygenase (5-LO) inhibitors that are key enzymes in the biosynthesis of eicosanoids is a promising approach. The di-tert-butylphenol derivatives R-830, S-2474, KME-4, and E-5110 represent potent dual COX-2/5-LO inhibitors. The incorporation of p-carborane and further substitution of the p-position resulted in four carborane-based di-tert-butylphenol analogs that showed no or weak COX inhibition but high 5-LO inhibitory activities in vitro. Cell viability studies on five human cancer cell lines revealed that the p-carborane analogs R-830-Cb, S-2474-Cb, KME-4-Cb, and E-5110-Cb exhibited lower anticancer activity compared to the related di-tert-butylphenols. Interestingly, R-830-Cb did not affect the viability of primary cells and suppressed HCT116 cell proliferation more potently than its carbon-based R-830 counterpart. Considering all the advantages of boron cluster incorporation for enhancement of drug biostability, selectivity, and availability of drugs, R-830-Cb can be tested in further mechanistic and in vivo studies.
... Examples of bioactive lipid mediators include eicosanoids and specialized pro-resolving mediators (SPM). Eicosanoids are arachidonic acid (AA)-derived lipids that play a role in both the induction and resolution of inflammation (6), whereas SPM are a functional class of lipids derived from omega-3 fatty acids such as docosahexaeneoic acid (DHA) or eicosapentaenoic acid (EPA) that are characterized by proresolving activity in a number of disease models (7). The temporal regulation of bioactive lipid class-switching from proinflammatory to proresolving activity is critical to the timely promotion of tissue healing and restoration of homeostasis (8). ...
Infection of C3H/HeJ (C3H) mice with Borrelia burgdorferi results in the development of a robust inflammatory arthritis that peaks around 3-4 weeks post-infection and then spontaneously resolves over the next few weeks. Mice lacking cyclooxygenase (COX)-2 or 5-lipoxygenase (5-LO) activity develop arthritis similar to wild-type mice but display delayed or prolonged joint resolution. Since 12/15-lipoxygenase (12/15-LO) activity is generally down-stream of both COX-2 and 5-LO activity and results in the production of pro-resolution lipids such as lipoxins and resolvins among others, we investigated the impact of 12/15-LO deficiency on the resolution of Lyme arthritis in mice on a C3H background. We found the expression of Alox15 (12/15-LO gene) peaked around 4-weeks post-infection in C3H mice suggesting a role for 12/15-LO in mediating arthritis resolution. A deficiency in 12/15-LO resulted in exacerbated ankle swelling and arthritis severity during the resolution phase without compromising anti-Borrelia antibody production and spirochete clearance. However, clearance of inflammatory cells was impeded. Therapeutic treatment of B. burgdorferi-infected C3H mice with lipoxin A4 (LXA4) near the peak of disease resulted in significantly decreased ankle swelling and a switch of joint macrophages to a resolving phenotype but did not directly impact arthritis severity. These results demonstrate that 12/15-LO lipid metabolites are important components of inflammatory arthritis resolution in murine Lyme arthritis and may be a therapeutic target for treatment of joint edema and pain for Lyme arthritis patients without compromising spirochete clearance.
... Clinically, arthritis is mainly manifested as pain, swelling and dysfunction of the tissues around the joints, which seriously lead to life-long disability and reduce the quality of patients' life [3][4][5]. At present, nonsteroidal anti-in ammatory drugs (NSAIDs) are often used to treat in ammation and pain clinically, which can inhibit the activity of COX, reduce the synthesis of prostaglandins and decrease the response of nociceptors to nociceptive stimuli [6,7]. However, NSAIDs are poorly water-soluble and have a serious irritating effect on the gastrointestinal tract, so most NSAIDs cannot be administered orally [8]. ...
The purpose of this study was to design a novel felbinac cataplasm with higher permeability than commercial product SELTOUCH® through using chemical enhancer strategy to reduce the times of administration and improve the compliance of patients. The novel felbinac cataplasm with high adhesion and good biocompatibility was prepared by calendar coating method. On the basis of previous research, the high-performance liquid chromatography (HPLC) analytical method of felbinac was established. According to 2020 Chinese pharmacopoeia (Ch. P), the paddle plate method was used to study the in vitro dissolution. The results showed the release of drug from self-made felbinac cataplasm could reach 90%. Subsequently, the effects of different kinds of penetration enhancers (N-methylpyrrolidone (NMP), isopropyl myristate (IPM) and propylene glycol (PG)) with the same percentage on the penetration of felbinac cataplasm were investigated. Propylene glycol (PG) was proved to be the most effective permeation enhancer among them. After screening different percentages of PG, 1% was added as the amount of permeation enhancer and the 12 h cumulative permeation amount was 189.03 µg/cm ² which was two times of the reference cataplasm (94.44 µg/cm ² ). The self-made felbinac cataplasm also had good stable permeability after placing at room temperature for 4 months. Finally, the tissue distribution study showed no matter in plasma, skin or muscle, the drug concentration of self-made cataplasm group was higher than reference cataplasm group. These data indicated that the self-made cataplasm provided a new reference for the development of felbinac dosage forms and promising alternative strategy for arthritis therapy.
... Acute pulmonary inflammation can caused by CLP induced polymicrobial sepsis leads to immunecell infiltration, mucuse production, vascular leak into the airways, and epithelial cell damage, so unregulated inflammationis an underlying cause of many chronic obstructive pulmonary disease, and fibrosis [23]. Elevated of eicosanoid 12 (S) HETE level are known to increased in response to inflammatory stimuli in the lung, and neutrophiles infiltration into the pulmonary space is a halmark feature of lung injury [24]. One of explanation that interprests association of 12 (S) HETE and lung injury, is that in an acute lung injury (ALI) mouse model undergo CLP induced sepsis led to induction of inflammation,increased vascular permeability, and upregulation of lipooxygenase, So production of lipooxygenase in alveolar macrophages and fibroblasts leads to bronchial epethelial injury via 12(S) HETE with leukotriene and pro-inflammatoru cytokines dependent mechanism. ...
Objective:
The aim: This study was undertaken to investigatethe possible lung protective potential effect of zileuton during polymicrobial sepsis, through modulation of inflammatory and oxidative stress pathway.
Patients and methods:
Materials and methods: 24 adult male Swiss-albino mice aged 8-12 weeks, with a weight of 25-35g, were randomized into 4 equal groups n=6, sham (laparotomy without CLP), CLP (laparotomy with CLP), vehicle (equivalent volume of DMSO 1 hour prior to CLP), and Zileuton (5 mg/kg 1 hour prior to CLP) group. After 24 hrs. of sepsis, the lung tissue harvested and used to assess IL-6, IL-1B, IL-17, LTB-4,12(S) HETE and F2-isoprostane as well as histological examination.
Results:
Results: Lung tissue inflammatory mediators IL-6, IL-1B, IL-17, LTB, 12 (S) HETE) and oxidative stress were carried out via ELISA. Lung tissue levels of IL-6, IL-1B, IL-17, LTB4, 12(S) HETE and oxidative stress (F2 isoprostan)level were significantly higher in sepsis group (p<0.05) as compared with sham group, while zileuton combination showed significant (p<0.05) lower level in these inflammatory mediators and oxidative stress as comparedto sepsis group. Histologically, All mice in sepsis group showed a significant (p<0.05) lung tissue injury, while in zileuton pretreated group showed significantly (p<0.05) reduced lung tissue injury.
Conclusion:
Conclusions: The results of the present study revealed that zileuton has the ability to attenuate lung dysfunction during CLP induced polymicrobial sepsis in male mice through their modulating effects on LTB4,12(S) HETE and oxidative stress downstream signaling pathways and subsequently decreased lungtissue levelsof proinflammatory cytokines (IL-1β, and IL-6,IL-17).
... Eicosanoids have significant activities in the regulation of normal physiological processes and disease pathogenesis in the human body 16,17 . Eicosanoids have pleiotropic roles in inflammation and immunity 18,19 . Many studies have focused on strategies for inhibiting the formation of inflammatory mediators that may contribute to risk of AF 20 . ...
Chronic inflammation is a continuous low-grade activation of the systemic immune response. Whereas downstream inflammatory markers are associated with atrial fibrillation (AF), upstream inflammatory effectors including eicosanoids are less studied. To examine the association between eicosanoids and incident AF. We used a liquid chromatography-mass spectrometry for the non-targeted measurement of 161 eicosanoids and eicosanoid-related metabolites in the Framingham Heart Study. The association of each eicosanoid and incident AF was assessed using Cox proportional hazards models and adjusted for AF risk factors, including age, sex, height, weight, systolic/diastolic blood pressure, current smoking, antihypertensive medication, diabetes, history of myocardial infarction and heart failure. False discovery rate (FDR) was used to adjust for multiple testing. Eicosanoids with FDR < 0.05 were considered significant. In total, 2676 AF-free individuals (mean age 66 ± 9 years, 56% females) were followed for mean 10.8 ± 3.4 years; 351 participants developed incident AF. Six eicosanoids were associated with incident AF after adjusting for multiple testing (FDR < 0.05). A joint score was built from the top eicosanoids weighted by their effect sizes, which was associated with incident AF (HR = 2.72, CI = 1.71–4.31, P = 2.1 × 10–5). In conclusion, six eicosanoids were associated with incident AF after adjusting for clinical risk factors for AF.
... In this study, EcN treatment increased leukotriene (a metabolite of arachidonic acid) intensity relative to untreated Def pig (indicating an impaired immune response) in PM analysis suggesting that such treatment reduced HRV disease and the inflammatory environment in malnourished hosts. Moreover, arachidonic acid is involved in the immune function of several organs and systems either directly or via conversion to eicosanoids (84,85). Eiconoids exhibit a role in inflammation, protection of mucosal integrity of the gastrointestinal tract, and regulation of aggregation of platelets. ...
Human rotavirus (HRV) is the most common cause of viral gastroenteritis in children, especially in developing countries, where the efficacy of oral HRV vaccines is reduced. Escherichia coli Nissle 1917 (EcN) is used to treat enteric infections and ulcerative colitis while tryptophan (TRP) is a biomarker of malnutrition, and its supplementation can alleviate intestinal inflammation and normalize intestinal microbiota in malnourished hosts. Supplementation of EcN + TRP to malnourished humanized gnotobiotic piglets enhanced immune responses and resulted in greater protection against HRV infection and diarrhea.
... Thus, a set of Lipid mediators acts as pro-inflammatory mediators that turn on inflammation, while some lipid mediators act as endogenous agonists to activate termination of inflammation by stimulating resolution. 11,12 ...
Severe Corona Virus Disease is characterized by angiocentric inflammation of lungs and cytokine storm leading to potentially fatal multiple organ failure. Several studies have shown the high levels of pro-inflammatory cytokines, indicative of a poor prognosis in COVID-19. Eicosanoids play an important role in the induction of inflammation and cytokine production, while anti-inflammatory and pro-resolving properties of some eicosanoic acid derivatives enable inflamed tissues to return to homeostasis through the resolution of inflammation by aiding the clearance of cell debris and downregulation of pro-inflammatory stimulants. This review attempts to provide an overall insight on the eicosanoids synthesis and their role in the resolution of inflammation in the context of Corona Virus infection.
... Increased levels of eicosanoid 12 (S) HETE were observed in the lungs in response to inflammatory triggers [34], and the leakage of neutrophils into the pulmonary space is a defining characteristic of lung damage. One explanation for the link between 12 (S) HETE and lung injury is that in a mouse model of acute lung injury (ALI), CLP-induced sepsis caused inflammation, increased vascular permeability, and upregulation of lipoxygenases. ...
One of the most complex clinical challenges facing medical practice is sepsis-induced lung dysfunction resulting from polymicrobial sepsis. Although many therapeutic approaches have been used in such clinical challenges, there is still further need for a new effective therapeutic approach. The objective of this study was to investigate if Montelukast could protect the lungs during polymicrobial sepsis by regulating inflammatory markers and the oxidative stress pathways. Twenty-four mature male Swiss-albino mice aged 8-12 weeks, with a weight of 20-30 g, were randomized into 4 equal groups (n=6), sham (laparotomy without cecal ligation and puncture (CLP)), CLP (laparotomy with CLP), vehicle 1 (equivalent volume of DMSO 1 hour prior to CLP), Montelukast (10 mg/kg IP 1 hour prior to CLP). Lung tissue pro-inflammatory mediators IL-6, IL-1β, IL-17, LTB-4 12(S) HETE, and oxidative stress were assessed using ELISA. The levels of F2 isoprostane were considerably greater in the sepsis group (p<0.05) as compared to the sham group, while Montelukast was significantly lower (p<0.05) in these inflammatory mediators and oxidative stress as compared to the sepsis group. Histologically, the lung tissue damage was significant (p<0.05) in all mice in the sepsis group, while Montelukast significantly reduced lung tissue injury (p<0.05). The current findings indicated that Montelukast could attenuate lung dysfunction during CLP-induced polymicrobial sepsis in male mice through their modulating effects on pro-inflammatory and oxidative stress downstream signalling pathways and subsequently decrease lung tissue cytokine concentrations (IL-1β, IL-6, IL-17, LTB-4, and 12(S)HETE).
... The understanding of SASP regulation in senescent cells is incomplete; however, 5lipoxygenase (5-LO) and cyclooxygenase-2 (COX-2) are upregulated in senescent cells [15][16][17] and are known to regulate inflammatory cytokines through eicosanoid synthesis [18,19]. Leukotrienes (LT) and prostaglandins (PG) are two classes of eicosanoids generated by the metabolism of arachidonic acid via the 5-LO and COX-2 pathways, respectively [20,21]. ...
Radiation-induced cutaneous ulcers are a challenging medical problem for patients receiving radiation therapy. The inhibition of cell senescence has been suggested as a prospective strategy to prevent radiation ulcers. However, there is no effective treatment for senescent cells in radiation ulcers. In this study, we investigated whether zileuton alleviated radiation-induced cutaneous ulcer by focusing on cell senescence. We demonstrate increased cell senescence and senescence-associated secretory phenotype (SASP) in irradiated dermal fibroblasts and skin tissue. The SASP secreted from senescent cells induces senescence in adjacent cells. In addition, 5-lipoxygenase (5-LO) expression increased in irradiated dermal fibroblasts and skin tissue, and SASP and cell senescence were regulated by 5-LO through p38 phosphorylation. Finally, the inhibition of 5-LO following treatment with zileuton inhibited SASP and mitigated radiation ulcers in animal models. Our results demonstrate that inhibition of SASP from senescent cells by zileuton can effectively mitigate radiation-induced cutaneous ulcers, indicating that inhibition of 5-LO might be a viable strategy for patients with this condition.
... In addition to metalloproteinases, tetracyclines also inhibit enzymes from the hydrolase group alpha-amylases and phospholipases. Phospholipase A2 is a key enzyme in the biosynthesis of inflammatory mediators such as prostaglandins [24]. ...
Tetracyclines are a group of antibiotics whose first representative was discovered over 70 years ago. Since then, they have been of great interest in dermatology. In addition to their antibacterial activity, they are able to inhibit metalloproteinases and exhibit anti-inflammatory, anti-apoptotic and antioxidant effects. The side effects have been thoroughly studied over the years, the most characteristic and important ones in daily dermatological practice being: phototoxicity, hyperpigmentation, onycholysis, photoonycholysis, induced lupus erythematosus, and idiopathic intracranial hypertension. In this article, we summarize the use of tetracyclines in infectious diseases and inflammatory dermatoses, and further discuss the instances where the efficacy and safety of tetracyclines have been highlighted over the past few years.
... These mechanisms include antioxidative and radical scavenging activities, regulation of cellular activities of the inflammation-related cells: mast cells, macrophages, lymphocytes, and neutrophils (for instance, some inhibit histamine release from mast cells and others inhibit T-cell proliferation), modulation of the enzymatic activities of arachidonic acid (AA) metabolizing enzymes such as phospholipase A2 (PLA2), cyclooxygenase (COX), and lipoxygenase (LOX) and the nitric oxide (NO) producing enzyme, nitric oxide synthase (NOS) (Vane and Botting, 1987;Chen, 2011). Inhibitions of these enzymes by anti-inflammatory medicinal plants products (AIMP) reduce the production of AA, prostaglandins (PG), leukotrienes (LT), and NO, which are crucial mediators of inflammation (Khanapure et al., 2007). Thus, the inhibition of these enzymes by AIMP is one of the important cellular mechanisms of anti-inflammation. ...
Background: Medicinal plant and plant products have shown tremendous potentials and are used beneficially in the treatment of inflammation and in the management of diseases with significant inflammatory components. Many medicinal plants employed as anti-inflammatory and anti-phlogistic remedies lack the gastro-erosive side effects of non-steroidal anti-inflammatory drugs (NSAID) or the plethora of unwanted side effects associated with steroidal anti-inflammatory drugs. In order to harness and optimise the applications of these herbs in inflammatory diseases, there is a need to understand how these herbs produce their anti-inflammatory actions. Materials and Methods: This paper is a review of some anti-inflammatory herbs and their molecular mechanisms of action. A literature search and analysis of published manuscript was employed to x-ray research findings that show how medicinal plants produce anti-inflammatory activities. Results: Many studies have shown that anti-inflammatory activities of herbal extracts and herb-derived compounds are mainly due to their inhibition of arachidonic acid (AA) metabolism, cyclo-oxygenase (COX), lipo-oxygenase (LOX), pro-inflammatory cytokines, inducible nitric oxide, and transcription activation factor (NF-κB). Some anti-inflammatory medicinal herbs are reported to stabilize lysosomal membrane and some cause the uncoupling of oxidative phosphorylation of intracellular signalling molecules. Many have also been shown to possess strong oxygen radical scavenging activities. Conclusion: Most of the mechanisms by which anti-inflammatory medicinal plants act are related and many herbal products have been shown to act through a combination of these molecular pathways.
Fennel waste is rich in compounds that may have beneficial effects on human health. For this reason, the most abundant metabolites in fennel were isolated as the following: quercetin-3-O-glucoside, quinic acid, 1,5-dicaffeoylquinic acid, kaempferol-3-O-glucuronide, and quercetin-3-O-glucuronide. After inducing inflammation in human bronchial epithelial cells by stimulating them with IL-1β, the cells were treated with the specialized Foeniculum vulgare metabolites at different concentrations to assess their anti-inflammatory effect. Eicosanoids, fatty acids, and sphingolipids were extracted from the cell medium and quantified by UPLC-ESI-QTRAP-MS/MS analysis. The anti-inflammatory activity of the metabolites isolated from fennel waste was demonstrated. They were able to alleviate the inflammatory state in human bronchial epithelium by modulating the metabolic expression of both pro- and anti-inflammatory eicosanoids, fatty acids, and sphingolipids. These findings suggest the potential use of fennel waste in the production of dietary supplements to alleviate the symptoms of chronic inflammatory diseases like asthma, chronic obstructive pulmonary disease (COPD), and idiopathic pulmonary fibrosis (IPF), where the continuous use of antiphlogistics may have significant side effects.
The octadecanoids are a broad class of lipids consisting of the oxygenated products of 18-carbon fatty acids. Originally referring to production of the phytohormone jasmonic acid, the octadecanoid pathway has been expanded to include products of all 18-carbon fatty acids. Octadecanoids are formed biosynthetically in mammals via cyclooxygenase (COX), lipoxygenase (LOX), and cytochrome P450 (CYP) activity, as well as nonenzymatically by photo- and autoxidation mechanisms. While octadecanoids are well-known mediators in plants, their role in the regulation of mammalian biological processes has been generally neglected. However, there have been significant advancements in recognizing the importance of these compounds in mammals and their involvement in the mediation of inflammation, nociception, and cell proliferation, as well as in immuno- and tissue modulation, coagulation processes, hormone regulation, and skin barrier formation. More recently, the gut microbiome has been shown to be a significant source of octadecanoid biosynthesis, providing additional biosynthetic routes including hydratase activity (e.g., CLA-HY, FA-HY1, FA-HY2). In this review, we summarize the current field of octadecanoids, propose standardized nomenclature, provide details of octadecanoid preparation and measurement, summarize the phase-I metabolic pathway of octadecanoid formation in mammals, bacteria, and fungi, and describe their biological activity in relation to mammalian pathophysiology as well as their potential use as biomarkers of health and disease.
The Siddha system is a traditional system of south India especially in Tamil Nadu. Thylam (medicated oil) is one of the 32 internal medicines. Karunkozhi thylam (KKT) is used to treat Vatha disease (degenerative disease). Qualitative and quantitative analysis ensures the quality and safety of drugs and minimizing contamination and adulteration risks. Weight/ml, refractive index (RI), density, iodine value (IV), acid value (AV) were analyzed as standardization parameter and GC-MS were employed to identify the active compound and test for heavy metals (lead, cadmium, mercury, arsenic), microbial contamination, test for specific pathogen (E.coli, Salmonella spp., Staphylococcus aureus, Pseudomonas aeruginosa), pesticide residue (organochlorine, organophosphorus, pyrethroids), test for Aflatoxins (B1, B2, G1, G2) were used as a safety measure. The result shows RI was 1.457, density was 1.213g/cm3, IV was 108.12g I/100g and AV was 0.86mg KOH/g. The safety parameters are within the acceptable limit. GC-MS shows the presence of oleic acid and n-hexodeconoeic acid that have anti-inflammatory activity. This study establishes a standardized protocol for KKT, ensuring quality, safety and efficacy. The findings have important implications for regulatory compliance and suggest areas for further research.
Objectives: Reports of traditional Chinese medicine (TCM)-related liver injury have increased over recent years; however, identifying susceptibility-related components and biomarkers remains challenging due to the heterogeneous nature of TCM and idiosyncratic drug-induced liver injury (IDILI). Psoraleae Fructus (PF) and Epimedii Folium (EF), commonly found in TCM prescriptions, have been implicated in IDILI, but their constituents and underlying mechanisms are poorly understood. Methods: In this study, we identified bavachin (Bav) and icariin (Ica) as susceptibility components for IDILI in PF and EF using a TNF-α-mediated mouse model. Lipidomics and transcriptomics were used to investigate their related mechanism. Results: Liver biochemistry and histopathology analyses revealed that co-exposure to Bav, Ica, and a non-toxic dose of TNF-α prestimulation induced significant liver injury, while Bav and Ica alone did not. Lipidomics identified seven differentially abundant metabolites in the Bav/Ica/TNF-α group compared to the Ica/TNF-α or Bav/TNF-α groups, mainly enriched in alpha-linolenic acid (ALA), arachidonic acid (AA), and linoleic acid (LA) metabolic pathways. Additionally, transcriptomics revealed 49 differentially expressed genes (DEGs) in the Bav/TNF-α vs Bav/Ica/TNF-α and Ica/TNF-α vs Bav/Ica/TNF-α groups, primarily associated with the PI3K/AKT/mTOR signaling pathway and sphingolipid metabolism. Integrative lipidomics and transcriptomics analyses identified significant positive correlations between five differential metabolites (DMs) - PC (O-16:0_14:1), PG (22:1_20:3), PI (16:0_14:1), PS (18:0_19:2), and TG (17:0_18:2_22:5) - and ten DEGs - Nr0b2, Btbd19, Btg2, Fam222a, Fam83f, Gtse1, Anln, Gja4, Srrm4, and Zfp13. Conslusions: Collectively, these results suggest that alterations in intracellular metabolism and gene expression levels may contribute to the synergistic induction of IDILI by the incompatible pair Bav and Ica in the presence of TNF-α.
Aim: The goal of this experiment was to examine if Clopidogrel might protect the lungs during sepsis by modulating the inflammatory and oxidative stress markers. Materials and Methods: Twenty-four adult male Swiss-albino mice aged 8-12 weeks, with a weighing of 20-30 g, were randomized into 4 equal groups (n=6): sham (Laparotomy without cecal ligation and puncture [CLP]), CLP (laparotomy plus CLP), vehicle (DMSO 1 hour prior to CLP), Clopidogrel (50 mg/g IP 1 hour before to CLP). ELISA was used to assess Lung tissue levels of pro-inflammatory and oxidative stress markers. Results: F2 isoprostane levels were significantly higher in the sepsis group (p<0.05) in comparison with sham group, while Clopidogrel was considerably lower (p<0.05) in the inflammatory and oxidative stress markers in comparison to sepsis group. Histologically, all mice in the sepsis group had considerable (p=0.05) lung tissue damage, but Clopidogrel considerably decreased lung tissue injury (p=0.05). Conclusion: Clopidogrel was found to reduce lung tissue cytokine concentrations (IL-1, TNF a, IL-6, F2 isoprostane, GPR 17, MIF) in male mice during CLP-induced polymicrobial sepsis by modulation of pro-inflammatory and oxidative stress cascade signaling pathways, to the best of our abilities, no study has looked at the effect of Clopidogrel on MIF levels.
Humans are exposed to complex mixtures of phthalates. Gestational exposure to phthalates has been linked to preeclampsia and preterm birth through potential pathways such as endocrine disruption, oxidative stress, and inflammation. Eicosanoids are bioactive signaling lipids that are related to a variety of homeostatic and inflammatory processes. We investigated associations between urinary phthalates and their mixtures with plasma eicosanoid levels during pregnancy using the PROTECT cohort in Puerto Rico (N = 655). After adjusting for covariates, we estimated pair-wise associations between the geometric mean of individual phthalate metabolite concentrations across pregnancy and eicosanoid biomarkers using multivariable linear regression. We used bootstrapping of adaptive elastic net regression (adENET) to evaluate phthalate mixtures associated with eicosanoids and subsequently create environmental risk scores (ERS) to represent weighted sums of phthalate exposure for each individual. After adjusting for false-discovery, in single-pollutant analysis, 14 of 20 phthalate metabolites or parent compound indices showed significant and primarily negative associations with multiple eicosanoids. In our mixture analysis, associations with several metabolites of low molecular weight phthalates - DEP, DBP, and DIBP - became prominent. Additionally, MEHHTP and MECPTP, metabolites of a new phthalate replacement, DEHTP, were selected as important predictors for determining the concentrations of multiple eicosanoids from different pathway groups. A unit increase in phthalate ERS derived from bootstrapping of adENET was positively associated with several eicosanoids mainly from Cytochrome P450 pathway. For example, an increase in ERS was associated with 11(S)-HETE (β = 1.6, 95% CI: 0.020, 3.180), (±)11,12-DHET (β = 2.045, 95% CI: 0.250, 3.840), 20(S)-HETE (β = 0.813, 95% CI: 0.147, 1.479), and 9 s-HODE (β = 2.381, 95% CI: 0.657, 4.104). Gestational exposure to phthalates and phthalate mixtures were associated with eicosanoid levels during pregnancy. Results from the mixture analyses underscore the complexity of physiological impacts of phthalate exposure and call for further in-depth studies to examine these relationships.
Hypertension is a major healthcare issue that afflicts one in every three adults worldwide and contributes to cardiovascular diseases, morbidity and mortality. Bioactive lipids contribute importantly to blood pressure regulation via actions on the vasculature, kidney, and inflammation. Vascular actions of bioactive lipids include blood pressure lowering vasodilation and blood pressure elevating vasoconstriction. Increased renin release by bioactive lipids in the kidney is pro-hypertensive whereas anti-hypertensive bioactive lipid actions result in increased sodium excretion. Bioactive lipids have pro-inflammatory and anti-inflammatory actions that increase or decrease reactive oxygen species and impact vascular and kidney function in hypertension. Human studies provide evidence that fatty acid metabolism and bioactive lipids contribute to sodium and blood pressure regulation in hypertension. Genetic changes identified in humans that impact arachidonic acid metabolism have been associated with hypertension. Arachidonic acid cyclooxygenase, lipoxygenase and cytochrome P450 metabolites have pro-hypertensive and anti-hypertensive actions. Omega-3 fish oil fatty acids eicosapentaenoic acid and docosahexaenoic acid are known to be anti-hypertensive and cardiovascular protective. Lastly, emerging fatty acid research areas include blood pressure regulation by isolevuglandins, nitrated fatty acids, and short chain fatty acids. Taken together, bioactive lipids are key contributors to blood pressure regulation and hypertension and their manipulation could decrease cardiovascular disease and associated morbidity and mortality.
Hypoxia is one of the serious stress challenges that aquatic animals face throughout their life. Our previous study found that hypoxia stress could induce neural excitotoxicity and neuronal apoptosis in Eriocheir sinensis, and observed that gamma-aminobutyric acid (GABA) has a positive neuroprotective effect on juvenile crabs under hypoxia. To reveal the neuroprotective pathway and metabolic regulatory mechanism of GABA in E. sinensis exposed to hypoxia stress, an 8-week feeding trial and acute hypoxia challenge were performed. Subsequently, we performed a comprehensive transcriptomic and metabolomic analysis of the thoracic ganglia of juvenile crabs. Differential genes and differential metabolites were co-annotated to 11 KEGG pathways, and further significant analysis showed that only the sphingolipid signaling pathway and the arachidonic acid metabolism pathway were significantly enriched. In the sphingolipid signaling pathway, GABA treatment significantly increased long-chain ceramide content in thoracic ganglia, which exerted neuroprotective effects by activating downstream signals to inhibit hypoxia-induced apoptosis. Moreover, in the arachidonic acid metabolism pathway, GABA could increase the content of neuroprotective active substances and reduce the content of harmful metabolites by regulating the metabolism of arachidonic acid for inflammatory regulation and neuroprotection. Furthermore, the decrease of glucose and lactate levels in the hemolymph suggests the positive role of GABA in metabolic regulation. This study reveals the neuroprotective pathways and possible mechanisms of GABA in juvenile E. sinensis exposed to hypoxia stress and inspires the discovery of new targets for improving hypoxia tolerance in aquatic animals.
Polyunsaturated fatty acids (PUFAs) are a diverse set of molecules with remarkable contributions to human physiology. They not only serve as sources of fuel but also cellular structural components as well as substrates that provide bioactive metabolites. A growing body of evidence demonstrates their role in inflammation. Inflammation in the presence of a polymicrobial biofilm contributes to the pathology of periodontitis. The role PUFAs in modulating immuno-inflammatory reactions in periodontitis is only beginning to be uncovered as research continues to unravel their far-reaching immunologic implications.
Objective:
The aim: This research aimed to show the achievement of Telecobalt60 radiation certainty using computed radiography, in comparation with non-verified computed radiography.
Patients and methods:
Materials and methods: This research is a quantitative study, randomized double-blind, and consecutive sampling design. The study was conducted by observing and com¬paring the data of verified computed radiography (VerC) computed radiograph for Telecobalt60 compared to the non-verified computed radiography (nVerC) Telecobalt60 data.
Results:
Results: The results showed that there are significant statistical differences in several measurement characteristics between the verified computed radiography arm and the non-verified computed radiography arm. All of the value divergences of the verified computed radiography arm are less than 7 mm while the non-verified computed radiography arm are 7 mm or more (P<0.050). Furthermore, all of the edge aspect of measurement in the verified computed radiography arms are less than the non-verified computed radiography, all without manual block utilization (P<0.050).
Conclusion:
Conclusions: We conclude that Telecobalt60 radiation certainty is significantly better achieved by using computed radiography, when compared to non-verified computed radiography Telecobalt60 use. This research contributes to provide evidence based for better Telecobalt60 radiation accuracy and quality of radiotherapy outcome by using computed radiography.
Objective:
The aim: To define morphological and immunohistochemical signs of placental disorders of women after syphilitic infection.
Patients and methods:
Materials and methods: The prospective study of 60 pregnant women with history of syphilitic infection (main group) and 57 pregnant patients without syphilis (control group) was conducted. The morphological and immunohistochemical study of the afterbirth was performed.
Results:
Results: In the placentas of women of the main group the following phenomena were found out: circulatory disorders in the form of hemorrhages into the intervillous space and the stroma of villi; accumulation of fibrinoid around villi with dystrophically altered stroma, compensatory-adaptive reactions resulted in hyperplasia of terminal villi and vessels in them, which provoked narrowing of the intervillous space and disruption of blood supply in it. Pathogenic immune complexes containing Ig G, M and C3 of the complement fraction were located in the central part of the placenta - 45.00% of cases, 16.67% - in the regional, 8.33% - in both parts. Immune complexes with Ig M content occurred in 38.33% of cases. The content of pathogenic immune complexes was the most concentrated in the placentas of women with latent forms and secondary recurrent syphilis - 60.00% of cases.
Conclusion:
Conclusions: changes in morphohistological and immunohistochemical examination of the placenta of this group of women confirmed the detrimental effect of syphilitic infection in the anamnesis on the structure of placenta during the next pregnancies.
Zusammenfassung
Die Bevölkerung in Deutschland ist mit einigen Mikronährstoffen, wie Vitamin D und E sowie einigen B-Vitaminen und Selen, nicht ausreichend versorgt. Doch gerade diese Nährstoffe sowie ω-3-Fettsäuren tragen dazu bei, im Alter Krankheiten vorzubeugen. ω-3-Fettsäuren bilden bspw. eine tragende Säule in der Anti-Aging-Medizin. Auch Ubichinol und Magnesium sind daran beteiligt, Alterungsprozesse zu verlangsamen, im Alter die Vitalität zu verbessern und der Entwicklung von Alterskrankheiten entgegenzuwirken.
Ximenynic acid is a natural conjugated acetylenic fatty acid and primarily exists in the Santalales order. This unusual fatty acid has shown its beneficial effects based on in vitro and in vivo studies. Here, we summarized the research findings of ximenynic acid concerning its anti-inflammation, anticancer, antimicrobial, and larvicidal activities. Ximenynic acid may present an exciting opportunity for the treatment of inflammatory diseases in clinics. Moreover, it involves long-chain fatty acid metabolism, which may regulate insulin secretion and improve insulin resistance. Ximenynic acid also has a vast potential market, because it is widely used in the cosmetics industry. With the discovery of its various biological activities, the demand for ximenynic acid is dramatically increasing. Therefore, it is essential to know how to obtain high-purity ximenynic acid. Natural ximenynic acid is primarily found in the seed oils of three families of Santalales, the Opiliaceae, Olacaceae, and Santalaceae, with total fatty acid content ranging from 1% to 95%. There are a variety of ways to separate and purify ximenynic acid from plant oil. The common ways are recrystallization and chromatography. Besides, ximenynic acid can also be acquired by employing synthesis technology, such as the well-studied chemical synthesis method. Ximenynic acid can be chemically synthesized using coaster oil as the precursor or from propargyl bromide and heptaldehyde, and might be biosynthesized from oleic acid during seed development by dehydrogenation of delta 9, 11 positions. Therefore, biosynthesis of ximenynic acid might be a promising way to obtain ximenynic acid in the future. But so far, the available information about ximenynic acid research is still limited. Further studies, especially on its activities, applications, and advanced preparation methods, are needed.
Eicosanoids containing a 12-hydroxyl group preceded by at least two conjugated double bonds are metabolized to 10,11-dihydro and 10,11-dihydro-12-oxo products by porcine polymorphonuclear leukocytes (PMNL) (Wainwright, S. L., Falck, J. R., Yadagiri, P., and Powell, W. S. (1990) Biochemistry 29, 10126-10135). These 10,11-dihydro metabolites could either have been formed by the direct reduction of the 10,11-double bond of the substrate, as previous evidence suggested, or via an initially formed 12-oxo intermediate. To gain some insight into the mechanism for the formation of dihydro products by this pathway, we investigated the metabolism of leukotriene B4 (LTB4), 12(S)-hydroxy-5,8,10,14-eicosatetraenoicacid(12(S)-HETE), and 12(R)-HETE by subcellular fractions from porcine PMNL. In the presence of NAD+ and a microsomal fraction from PMNL, each of the above 12-hydroxyeicosanoids was converted to a single product with a lambda max approximately 40 nm higher than that of the substrate, indicating that the conjugated diene or triene chromophore had been extended by one double bond, presumably by oxidation of the 12-hydroxyl group to an oxo group. In the case of LTB4, this was confirmed by mass spectrometry, which indicated that the product was identical to 12-oxo-LTB4. LTB4 was not converted to any products by a cytosolic fraction from PMNL, but was converted to both 10,11-dihydro-LTB4 and 10,11-dihydro-12-oxo-LTB4 by the 1500 x g supernatant in the presence of NAD+. Negligible amounts of dihydro products were formed in the presence of NADH or NADPH, suggesting that initial oxidation of the 12-hydroxyl group is a requirement for reduction of the 10,11-double bond. Consistent with this hypothesis, 12-oxo-LTB4 was rapidly metabolized to 10,11-dihydro-12-oxo-LTB4 by the cytosolic fraction in the presence of NADH. Only small amounts of this product, along with some LTB4, were formed by the microsomal fraction. These results indicate that the initial step in the formation of 10,11-dihydro products from 12-hydroxyeicosanoids is oxidation of the 12-hydroxyl group by a microsomal 12-hydroxyeicosanoid dehydrogenase in the presence of NAD+, which is followed by reduction of the olefinic double bond by a cytosolic delta 10-reductase in the presence of NADH.
The ability of leukotrienes derived from eicosapentaenoic acid were compared with counterpart leukotrienes derived from arachidonic acid in terms of their ability to affect susceptibility of the stomach to injury induced by a topical irritant and their ability to alter gastric blood flow. Intra-arterial infusion of leukotriene C4 (LTC4) and LTD4 (0.1-3 micrograms/kg/min for 5 min) produced dose-dependent increases in gastric mucosal damage induced by topically applied 20% ethanol, as assessed macroscopically, by changes in transmucosal potential difference and by measurement of efflux of protein into the gastric lumen. Similar doses of LTC5 or LTD5 did not produce significant changes in any of these three parameters, when compared with control rats receiving the vehicle. With a higher dose of LTC5 or LTD5 (5 micrograms/kg/min), significant damage was observed. LTC4 and LTD4 were also found to be more potent at reducing gastric blood flow than LTC5 and LTD5. These results demonstrate that the peptido-leukotrienes derived from eicosapentaenoic acid (LTC5 and LTD5) are on the order of five times less potent than the leukotrienes derived from arachidonic acid (LTC4 and LTD4), in terms of increasing the susceptibility of the gastric mucosa to damage and reducing gastric blood flow. These results may have important implications in terms of the hypothesis that fish oil diets may be protective or may accelerate healing in ulcerative diseases of the gastrointestinal tract.
The interest in lipid mediators of inflammation as potential contributors to the pathogenesis of gastric ulcer has increased markedly over the past 20 yr. Although a great deal is known about the actions of mediators such as leukotrienes, thromboxane, and platelet-activating factor in experimental models of ulceration, evidence supporting a role for these mediators in human gastric ulcer is sorely lacking. This review attempts to answer a number of questions regarding the contribution of these mediators to the pathogenesis of gastric ulceration and the possible use of specific inhibitors, antagonists, and dietary manipulation in the treatment of gastric ulcer. Potential directions for future research in this field are suggested as are some of the pitfalls to be avoided in such studies.
Granulocytes and mononuclear cells were isolated from the blood of asthmatic and healthy children. Stimulation with ionophore A 23187 induced a significantly higher leukotriene C4 (LTC4) generation from granulocytes of asthmatic children than from granulocytes of healthy controls. In contrast, mononuclear cells from patients and controls did not differ in their ability to produce LTC4. Additional analysis showed that the difference in LTC4 generation of granulocytes was due to increased formation but not to decreased oxidative degradation of LTC4. Analysis of LTC4 generation of purified neutrophils and eosinophils revealed that LTC4 was generated almost exclusively by eosinophils and, in particular, the hypodense population. Granulocytes from patients with a history of severe asthma displayed a higher LTC4 formation than granulocytes from patients with less severe disease.
The stereochemistry and double bond geometry of a novel series of leukocyte-derived arachidonic acid metabolites, the lipoxins, was determined by comparison to pure unambiguous synthetic standards. The lipoxins were found to be a mixture of four lipoxin A isomers and two lipoxin B isomers. In determining the biosynthesis of these compounds, they were shown to be formed via a tetraene epoxide. In addition, it was shown that all of the lipoxin isomers formed by the incubation of 15-hydroperoxyeicosatetraenoic acid with human leukocytes were also formed by nonenzymatic hydrolysis of this tetraene epoxide.
Aspirin (acetylsalicylic acid) reduces the odds of serious atherothrombotic vascular events and death in a broad category of high risk patients by about one-quarter. The mechanism is believed to be inhibition of thromboxane biosynthesis by inactivation of platelet cyclo-oxygenase-1 enzyme. However, aspirin is not that effective; it still fails to prevent the majority of serious vascular events. Mechanisms that may account for the failure of aspirin to prevent vascular events include non-atherothrombotic causes of vascular disease, non-adherence to aspirin therapy, an inadequate dosage, alternative ‘upstream’ pathways of platelet activation (e.g. via stimulation of the ADP, collagen or thrombin receptors on platelets), aspirin-insensitive thromboxane biosynthesis (e.g. via monocyte cyclo-oxygenase-2), or drugs that interfere with the antiplatelet effects of aspirin. Genetic or acquired factors may further modify the inhibitory effects of aspirin on platelets (e.g. polymorphisms involving platelet-associated proteins, increased platelet turnover states).
Identification and treatment of the potential causes of aspirin failure could prevent at least another 20% of serious vascular events (i.e. over and above those that are currently prevented by aspirin). There is currently no role for routine laboratory testing to measure the antiplatelet effects of aspirin. Clinicians should ensure that patients at high risk of atherothrombosis (>3% risk over 5 years) are compliant with aspirin therapy and are taking the correct dosage (75–150 mg/day). Patients who cannot tolerate aspirin, are allergic to aspirin, or have experienced recurrent serious atherothrombotic events whilst taking aspirin, should be treated with clopidogrel, and patients with acute coronary syndromes benefit from the combination of clopidogrel plus aspirin. Future research is required to standardize and validate laboratory testing of the antiplatelet effects of aspirin and to identify treatments that can both improve these laboratory measures and reduce the risk of future atherothrombotic events.
The first total synthesis of the methyl ester of 20-oxo-LTB426 is described. The key synthon 6 is an advanced new intermediate which has been used in the synthesis of LTB41, 20-oxo-LTB4 methyl ester 26, and 20-hydroxy-LTB42. The synthetic 26 has been used to study the cytosolic aldehyde dehydrogenase-catalyzed oxidation of LTB4 to its ω-carboxy metabolite.
Background: It is the rare physician who includes diet therapy and nutritional supplements in patient care. Perhaps this is because chiropractic and medical schools devote very few classroom hours to nutrition. It is also possible that physicians are under the misconception that a detailed biochemical understanding of each individual disease is required before nutritional interventions can be used. Objective: The purpose of this article is two-fold: (1) to demonstrate that chronic pain and other degenerative conditions encountered in clinical practice have similar biochemical etiologies, such as a diet-induced proinflammatory state, and (2) to outline a basic nutritional program that can be used by all practitioners. Data Sources: The data were accumulated over a period of years by reviewing contemporary articles and books and subsequently by retrieving relevant articles. Articles were also selected through MEDLINE and manual library searches. Results: The typical American diet is deficient in fruits and vegetables and contains excessive amounts of meat, refined grain products, and dessert foods. Such a diet can have numerous adverse biochemical effects, all of which create a proinflammatory state and predispose the body to degenerative diseases. It appears that an inadequate intake of fruits and vegetables can result in a suboptimal intake of antioxidants and phytochemicals and an imbalanced intake of essential fatty acids. Through different mechanisms, each nutritional alteration can promote inflammation and disease. Conclusion: We can no longer view different diseases as distinct biochemical entities. Nearly all degenerative diseases have the same underlying biochemical etiology, that is, a diet-induced proinflammatory state. Although specific diseases may require specific treatments, such as adjustments for hypomobile joints, β-blockers for hypertension, and chemotherapy for cancer, the treatment program must also include nutritional protocols to reduce the proinflammatory state.
The first total synthesis of 5-oxo-12(S)-hydroxy-6(E),8(Z),10(E), 14(Z)-eicosatetraenoic acid (5-oxo-12-HETE) 6 and its 8-trans-isomer 7 is reported. The synthetic 5-oxo-12-HETE 6 and its 8,9-trans-isomer 7 were used to identify their formation in mixtures of platelets and neutrophils by transcellular metabolism.
The first total synthesis of the 5(S)-hydroxy-10,11-dihydro-12-oxo-6(Z),8(E),14(Z)-eicosatrienoic acid (10,11-dihydro-12-oxo-LTB4) (3) is reported. This compound is a key pivotal intermediate in the biotransformation of LTB4 by the so-called “LTB4 reductase pathway”.
The first total synthesis of an ω-amino 5-HETE derivative 27 has been accomplished by a new counterclockwise strategy, in which C-1 is constructed first and C-20 last. The ω-amino 5-HETE derivative was transformed to an affinity chromatography ligand, the biotinylated 5-HETE 30. This affinity chromatography ligand is aimed at purifying the 5-hydroxyeicosanoid dehydrogenase enzyme, which is responsible for the conversion of 5-HETE to 5-oxo-ETE, a potent eosinophil chemotactic factor.
The first total synthesis of the highly unstable biological mediator 12-etoicosaetranoic acid (12-KETE) and its 8,9-trans -isomer is presented. The strategy focuses on the stable precursor dithiane and its conversion to and . Biochemical experiments show that the two isomers are not interconverted in vivo, raising the possibility that the trans-isomer may be formed by a primary biochemical mechanism.
Background: The cysteinyl leukotrienes (CysLTs) mediate their biological actions through two receptors: CysLT1 receptor and CysLT2 receptor. Objective: This study was undertaken to examine the direct effects of CysLTs on eosinophils, such as chemotaxis and degranulation, focusing on CysLT1. Methods: Eosinophils were isolated from venous blood from normal volunteers who had no history of allergy (purity >99%). They were subjected to reverse transcription-PCR analysis and flow-cytometric analysis for CysLT1. Binding assays were performed with [3H]LTD4. Purified eosinophils loaded with Fura-2 acetoxymethyl ester were stimulated with CysLTs, and Ca2+ influx was measured. Eosinophil migration in response to CysLTs was measured using a 96-well multiwell Boyden chamber. Eosinophils were treated with LTD4 at 10–6M for 60 min followed by incubation for 4 h at 37°C in the presence or absence of IL-5 and eosinophil-derived neurotoxin (EDN) release was evaluated. Results: The expression of the mRNA and protein of CysLT1 on eosinophils and [3H]LTD4-specific binding to eosinophils were observed. Neither Th1 cytokine (IFN-γ) nor Th2 cytokines (IL-4 or IL-5) affected CysLT1 expression in eosinophils. CysLTs induced an increase in intracellular free Ca2+ in eosinophils via CysLT1, as suggested by the efficient inhibition by a CysLT1 antagonist, pranlukast, in addition to the rank order of potency being LTD4, LTC4 and LTE4. LTD4 stimulated eosinophils to migrate at 10–6M via CysLT1. LTE4 also induced significant eosinophil migration at 10–6M. LTD4 enhanced EDN release induced by IL-5 via CysLT1. Conclusion: CysLTs induce migration and enhance degranulation in eosinophils via CysLT1. Accordingly, interaction of CysLTs and CysLT1 on eosinophils has the potential to play a prominent role in the pathophysiology of asthma.
In 1975, Hamberg et al.
1 reported evidence for the existence of an unstable platelet-aggregating factor which they named thromboxane A2 (TXA2) and for which they proposed a novel bicyclic oxetane structure (1, below) based on the short half-life of the factor (t
1/2(37°C) = 32 s at pH 7.4) and the isolation of degradation products related to thromboxane (TXB2) (2, below). As natural TXA2 has not yet been isolated and characterized as a pure compound, we have synthesized the proposed structure (1) from TXB2 and compared its biological properties with those of authentic, biologically generated material. Here we present evidence that synthetic material having structure (1) is indistinguishable from platelet-derived TXA2 in various biological assays and that the proposed structure (1) for TXA2 is correct.
The first total synthesis of a potent inflammatory mediator 5-oxo-6(E),8(Z),11(Z),14(Z)-eicosatetraenoic acid (5-oxo-ETE) 2 and its biotransformation product 6,7-dihydro-5-oxo-ETE 5 is reported. A convergent synthesis for the unstable title compounds is accomplished via two synthons, dithiolane aldehyde 13 and bisdienyl phosphonium bromide 19. The synthetic 5-oxo-ETE 2 and its 8,9-trans isomer 3 were used to unequivocally confirm the structure of the biologically derived mediators. In addition, using synthetic 6,7-dihydro-5-oxo-ETE 5 we have been able to identify in neutrophils the formation of 6,7-dihydro-5-oxo-ETE 5.
The recent discovery of an alternative form cyclooxygenase (cyclooxygenase-2, COX-2), which has been proposed to play a significant role in inflammatory conditions, may provide an opportunity to develop anti-inflammatory drugs with fewer side effects than existing non-steroidal anti-inflammatory drugs (NSAIDs). We have now identified 6-[(2,4-difluorophenyl)-thio]-5-methanesulfonamido-1-indanone++ + (20) (L-745,337) as a potent, selective, and orally active COX-2 inhibitor. The structure-activity relationships in this series have been extensively studied. Ortho- and para-substituted 6-phenyl substitutents are optimal for in vitro potency. Replacement of this phenyl ring by a variety of heterocycles gave compounds that were less active. The methanesulfonamido group seems to be the optimal group at the 5-position of the indanone system. Compound 20 has an efficacy profile that is superior or comparable to that of the nonselective COX inhibitor indomethacin in animal models of inflammation, pain, and fever and appears to be nonulcerogenic within the dosage ranges required for functional efficacy. Although 20 and its oxygen linkage analog 2 (flosulide) are equipotent in the in vitro assays, compound 20 is more potent in the rat paw edema assay, has a longer t1/2 in squirrel monkeys, and seems less ulcergenic than 2 in rats.
IntroductionHuman Platelets, Thromboembolic Disorders, and NONitrovasodilators Glyceryl Trinitrate, Nitroglycerin (GTN)Isosorbide Dinitrate (ISDN) and Isosorbide Mononitrate (ISMN)Sodium Nitroprusside (SNP)Oxatriazolium NO Donors SydnoniminesNitrosothiol NO Donors S-Nitroso-glutathione (GSNO)L-Arginine {S(+)-2-Amino-5-[(aminoiminomethyl)amino]pentanoic acid} (L-arg)NCX-4016 [2-Acetoxybenzoate 2-(1-nitroxy-methyl)-phenyl ester]Conclusion and Future Prospects Glyceryl Trinitrate, Nitroglycerin (GTN)Isosorbide Dinitrate (ISDN) and Isosorbide Mononitrate (ISMN)Sodium Nitroprusside (SNP) Sydnonimines S-Nitroso-glutathione (GSNO)
We investigated the effect of FR140423 (3-(difluoromethyl)-1-(4-methoxyphenyl)-5-[4-(methylsulphinyl)phenyl]pyrazole), a novel and selective cyclo-oxygenase (COX)-2 inhibitor, in rat adjuvant arthritis. The results were compared with that of indomethacin.
We tested the inhibitory effects of FR140423 on paw oedema and the formation of the arachidonic acid metabolites prostaglandin (PG) E2 and leukotriene (LT) B4 in inflamed paws immunized with heat-killed and dried Mycobacterium tuberculosis. Oral administration of FR140423 showed a dose-dependent anti-inflammatory effect. This effect was two- to threefold more potent than that of indomethacin. The increase of PGE2 and LTB4 in inflamed paws was associated with the development of paw swelling. FR140423 and indomethacin dose-dependently suppressed the level of PGE2 but not LTB4 in arthritic paws. Unlike indomethacin, FR140423 did not induce gastric lesions even at doses up to 10 mg kg−1 in arthritic rats.
FR140423 has a potent anti-inflammatory effect mediated by inhibition of PGE2 produced by COX-2 in inflamed tissues. The safety profile of FR140423 appears to be an improvement on the safety profile of indomethacin.
A cDNA clone coding for the guinea pig leukotriene B4 (BLT) receptor has been isolated from a lung cDNA library. The guinea pig BLT receptor has an open reading frame corresponding to 348 amino acids and shares 73% and 70% identity with human and mouse BLT receptors, respectively. Scatchard analysis of membranes prepared from guinea pig and human BLT receptor-transfected human embryonic kidney (HEK) 293 EBNA (Epstein–Bar Virus Nuclear Antigen) cells showed that both receptors displayed high affinity for leukotriene B4 (Kd value of ∼0.4 nM) and were expressed at high levels (Bmax values ranging from 9 to 12 pmol/mg protein). The rank order of potency for leukotrienes and related analogs in competition for []leukotriene B4 specific binding at the recombinant guinea pig BLT receptor is leukotriene B4>20-OH-leukotriene B4>12(R)-HETE ((5Z,8Z,10E,12(R)14Z)-12-hydroxyeicosatetraen-1-oic acid)>12(S)-HETE ((5Z,8Z,10E,12(S)14Z)-12-Hydroxyeicosatetraen-1-oic acid)>20-COOH-leukotriene B4>U75302 (6-(6-(3-hydroxy-1E,5Z-undecadienyl)-2-pyridinyl)-1,5-hexanediol)≫leukotriene C4=leukotriene D4=leukotriene E4. For the human receptor the rank order of 12(S)-HETE, 20-COOH-leukotriene B4 and U75302 was reversed. Xenopus melanophore and HEK aequorin-based reporter gene assays were used to demonstrate that the guinea pig and human BLT receptors can couple to both the cAMP inhibitory and intracellular Ca2+ mobilization signaling pathways. However, in the case of the aequorin-expressing HEK cells (designated AEQ17-293) transfected with either the guinea pig or human BLT receptor, expression of Gα16 was required to achieve a robust Ca2+ driven response. Leukotriene B4 was a potent agonist in functional assays of both the guinea pig and human BLT receptors. U-75302 a leukotriene B4 analogue which possesses both agonistic and antagonistic properties behaved as a full agonist of the guinea pig and human BLT receptors in AEQ17-293 cells and not as an antagonist. The recombinant guinea pig BLT receptor will permit the comparison of the intrinsic potencies of leukotriene B4 receptor antagonists used in guinea pig in vivo models of allergic and inflammatory disorders.
Plasma renin activity (PRA) was measured in rabbits before and after infusion of the prostaglandin precursor, arachidonic acid (C20:4) and of the prostaglandin synthesis inhibitor, indomethacin. Non-hypotensive doses of C20:4 (10–15 μg/kg/min) increased PRA from 45 ± 7.3 to 91 ± 16 ng/ml/hr (n = 6, p < 0.05). Conversely, indomethacin decreased PRA from 45 ± 11 to 27 ± 6.0 ng/ml/hr (n = 4, p < 0.001). The results suggest a relationship between the renin and prostaglandin systems.
Albeit its exact pathogenesis is still ambiguous; aspirin-intolerant asthma is one of several types of asthma for which antileukotriene therapy is useful, because it is widely accepted that bronchial over-production of leukotrienes may be involved in its pathogenesis. Pranlukast (8-[p-(4-phenylbutyloxy) benzol] amino-2-(tetrazol-5-yl)-4-oxo-4H-1-benzopyran hemihydrate), a selective cysteinyl leukotriene receptor antagonist, is now widely used in the treatment of asthma.
This study was designed to investigate the protective effect of pranlukast on airway sensitivity to sulpyrine provocation testing, bronchial responsiveness to methacholine provocation testing, and to investigate whether this protective activity is associated with a reduction in aspirin-induced excretion of urinary LTE4 (uLTE4), a marker of the cysteinyl leukotriene (LT) overproduction that participates in the pathogenesis of aspirin-induced asthma.
We assessed the effects of pretreatment with pranlukast on bronchoconstriction precipitated by inhalation of methacholine and sulpyrine in 16 adult patients with mild or moderate aspirin-intolerant asthma; those who were in stable clinical condition and were hypersensitive to sulpyrine provocation testing were allocated to this study. A double-blind, randomized, crossover design was used. uLTE4 was measured using combined reverse-phase high-performance liquid chromatography (rp-HPLC)/enzyme immunoassay.
Pranlukast protected against analgesic-induced bronchoconstriction through mechanisms that were not related to the bronchodilator property, but were related to the improvement both of bronchial hyperresponsiveness and hypersensitivity to analgesic (P < 0.005 and P < 0.0001). Pranlukast showed little effect on excretion of uLTE4.
These results support the hypothesis that cysteinyl leukotriene is one of the most important components in the pathogenesis of aspirin-intolerant asthma. Pranlukast improves not only hypersensitivity to analgesic, but also bronchial hyperresponsiveness in aspirin-intolerant asthma. It is also possible that pranlukast has another anti-asthmatic effect besides that of a leukotriene receptor antagonist.
Infusion of a variety of agonists (bradykinin, angiotensin II, arachidonic acid and ATP) into rabbit kidneys perfused after 3 days of ureteral obstruction led to the release of a substance which contracts the rabbit aorta. The contralateral (nonobstructed) kidney and the normal kidney did not release rabbit aorta contracting substance with doses of bradykinin up to 1000 ng, but high doses of arachidonic acid (AA) and ATP cause the release of detectable levels of rabbit aorta contracting substance. The rabbit aorta contracting substance appearing in the renal venous effluent after drug treatment was labile and disappeared with a t.5 of 37 sec at 37°C suggesting that the labile constrictor was thromboxane A2 (TxA2). Cortical and medullary microsomal fractions obtained from hydronephrotic kidneys were incubated with the endoperoxide prostaglandin (PG) H2 at 0°C for 2 min and generated a potent labile t.5 of 40 sec at 37°C) contractile substance. The enzymatic generation of the contractile substance was inhibited by imidazole, a specific inhibitor of thromboxane synthetase. Radiochemical identification of the contractile substance was studied by incubating microsomes (37°C) from cortex or medulla of ureter-obstructed kidneys with [14C]AA. The primary products formed after incubation (25 min) of renal medullary microsomes with [14C]AA were PGE2 (25% of [14C]AA converted) and thromboxane B2 (TxB2, 8%) and 7.5% PGE2 and 5.0% TxB2 from the cortex. The radioactive TxB2 zone was abolished when the incubations were carried out in the presence of 5 mM imidazole. Microsomes prepared from the cortex and medulla of the contralateral kidney possessed comparable rates of synthesis of PGE2, but formed no TxB2. Thus, TxA2 biosynthesis in cortex and medulla is unmasked by ureteral obstruction and this temporal appearance of cortical biosynthesis of thromboxane A2 may be important to the alteration of renal blood flow occurring in chronic ureteral obstruction.
The recent discovery of potent, specific, long-acting thromboxane receptor antagonists, like SQ 33,961, mandated that studies be conducted to follow up an earlier study, which showed potential antiulcer activity of the short-acting thromboxane antagonist, SQ 28,668, in the taurocholic acid gastric erosion model in rats. In experiments conducted with the same taurocholic acid protocol, SQ 33,961 caused a dose-related reduction in taurocholate-induced gastric erosions, with an ID50 value of 12 micrograms/kg, i.p. In additional studies, aspirin and indomethacin were shown to produce gastric erosions in rats, and SQ 33,961 also inhibited gastric erosion in response to these anti-inflammatory drugs. The ID50 values were 0.24 and 0.26 mg/kg i.p. vs. aspirin (200 mg/kg, p.o.) and indomethacin (200 mg/kg, s.c.), respectively. The inhibition of aspirin-induced gastric injury by SQ 33,961 was confirmed histologically. This gastroprotective activity was not peculiar to SQ 33,961, because the structurally unrelated thromboxane receptor antagonist, BM 13,505, also significantly inhibited the development of aspirin-induced gastric lesions. In a more severe model, SQ 33,961 (10 mg/kg, i.p.) reduced gastric erosions by only 32% (not significant) 1 hr after ethanol ingestion (1 ml, p.o.) in rats. SQ 33,961 did not inhibit the antiphlogistic activity (carrageenan paw edema assay) of indomethacin, nor did it inhibit the analgesic activity (phenylquinone writhing assay) of aspirin. A dose of SQ 33,961 producing > or = 95% inhibition of nonsteroidal anti-inflammatory drug-induced gastric erosion (10 mg/kg, i.p.) produced a 37% reduction in the volume of gastric secretion without changing the titratable acidity of gastric contents.(ABSTRACT TRUNCATED AT 250 WORDS)
Salicylates and steroids remain the mainstay of treatment for inflammatory bowel disease. New formulations which attempt to lower the rates of side effects are under evaluation. The value of azathioprine has been established in ulcerative colitis and cyclosporin has been shown to be of value. Dietary therapy in Crohn's disease has been the focus of a large amount of research and benefits have been demonstrated. New therapies including bioengineered drugs are anticipated.
The time course of leukotriene generation in the adult respiratory distress syndrome (ARDS) was investigated by measurement of urinary leukotriene E4 (LTE4) excretion, the major urinary LT metabolite in humans. Sequential measurements were made in nine subjects entered into the study within 48 h of the onset of ARDS, defined by an arterial/alveolar PO2 ratio of less than 0.3 and radiographic evidence of diffuse bilateral pulmonary edema. Initial urinary LTE4 excretion was significantly elevated (1.250 +/- 0.050 ng/mg creatinine sulphate; n = 7) compared with a non-ARDS postoperative group (0.254 +/- 0.114 ng/mg; n = 5) and normal control subjects (0.035 +/- 0.010 ng/mg; n = 12). LTE4 excretion in the first 24 h was estimated to be 6.9 micrograms, representing a release of 0.1 micrograms/kg/h of peptido leukotrienes into the bloodstream. These values were physiologically important based on a comparison with the increased urinary LTE4 excretion observed after antigen-induced bronchoconstriction in allergic asthmatics (baseline LTE4, 0.06 +/- 0.04 ng/mg; postantigen, 0.56 +/- 0.14 ng/mg; 0.17 micrograms LTE4/24 h; n = 8). In subjects with ARDS, this pathologic LTE4 excretion persisted during a subsequent 5-day study period. Leukotriene E4 excretion was associated with persistent abnormalities in gas exchange, pulmonary edema, and lung compliance, suggesting an important role for peptido leukotrienes in the pathophysiology of ARDS.
There is increasing evidence that nitric oxide (NO) synthetized in vascular endothelium and in platelets by NO synthase influences vascular tone, down regulates platelet function and platelet-vessel wall interaction both in vitro and in vivo. We investigated the effect of a NO synthase inhibitor, NG-mono-methyl-L-arginine (L-NMMA, 100 mg/kg iv) on platelet-endothelial cell interaction in rabbit arteries ex vivo using scanning electron microscope (SEM). The effect of L-NMMA was examined on intact endothelium and on that damaged by arterial constriction. The infusion of L-NMMA increased systemic blood pressure and decreased carotid blood flow, however, it did not change the appearance of an intact endothelium and did not result in platelet activation on intact endothelial cells. In contrast, SEM of endothelial areas damaged by constriction showed extensive platelet adhesion and aggregation on subendothelium. These morphological changes were not detected in control animals with intact or damaged by arterial constriction endothelium. These results show that under physiological conditions, the inhibition of NO synthase alone does not result in platelet activation in vivo. However, when combined with endothelial injury it may lead to platelet activation and thrombosis.
Thromboxane A2 (TXA2) and its precursor prostaglandin H2 (PGH2) induce platelet aggregation and vascular contraction through shared cell surface receptors commonly referred to as TXA2 or TXA2/PGH2 receptors. Whether different subclasses of TXA2/PGH2 receptors exist in platelets and vascular smooth muscle cells is controversial. In this study, TXA2 receptors on washed rat and human platelets and cultured rat aortic smooth muscle cells (RASMC) were characterized using radioligand competition binding assays with the 125I-labeled TXA2/PGH2 receptor agonist [1S-(1 alpha,2 beta(5Z),3 alpha(1E,3R*),4 alpha)] -7- [3-(3-hydroxy-4-(4'-iodophenoxy)-1-butenyl) -7- oxabicyclo-[2.2.1]- heptan-2-yl] -5- heptenoic acid (I-BOP) and various agonists and antagonists. Scatchard analyses of equilibrium binding data revealed Kd values of 205 +/- 68 pM (N = 6), 2.2 +/- 0.3 nM (N = 9) and 310 +/- 60 pM (N = 7) and Bmax values of 1.3 +/- 0.45 fmol/10(6) platelets, 2.8 +/- 0.2 fmol/10(6) platelets and 20.9 +/- 2.2 fmol/10(6) cells for rat and human platelets and RASMC, respectively. Concentration-dependent increases in intracellular free Ca2+ concentrations induced by I-BOP were observed in RASMC loaded with the calcium sensitive dye fura-2. The IC50 values for various TXA2/PGH2 analogues in competition binding assays with 125I-BOP were determined. Based on their IC50 values, the rank orders were I-BOP less than L657925 less than ONO11113 less than or equal to SQ29548 less than PTA-TPO less than PTA-NO less than or equal to L657926 less than or equal to I-PTA-OH less than PTA-OH[2] = meta-I-PTA-PO less than or equal to ONO11120[2] = ONO11120[1] less than PTA-OH[1] in rat platelets. I-BOP less than SQ29548 less than PTA-TPO = L657925 less than or equal to ONO11113 less than I-PTA-OH less than PTA-NO less than or equal to meta-I-PTA-PO less than or equal to PTA-OH[2] less than ONO11120[2] less than or equal to ONO11120[1] less than L657926 less than or equal to PTA-OH[1] in human platelets, and I-BOP less than L657925 less than ONO11113 less than or equal to SQ29548 less than ONO11120[2] less than or equal to L657926 less than or equal to PTA-OH[2] less than PTA-TPO less than ONO11120[1] less than I-PTA-OH less than meta-I-PTA-PO less than PTA-NO less than PTA-OH[1] in RASMC.(ABSTRACT TRUNCATED AT 400 WORDS)
Human monocytes in monolayers were challenged with the calcium ionophore A23187. Methanol trapping of the products in the cell-free supernatants, followed by analysis on HPLC and by ultraviolet spectroscopy, revealed the presence of two compounds, which exhibited a conjugated-triene spectrum and chromatographed with the compounds formed when synthetic leukotriene (LT) A4 was added to warm acidified methanol. Furthermore, addition of purified LTA4 hydrolase to the cell-free supernatant of monocytes, stimulated with the ionophore A23187, resulted in increased levels of LTB4. These results indicate that monocytes release LTA4 extracellularly after activation with the calcium ionophore.
Incubation of monocytes together with monoclonal lymphocytic cells, of both B and T cell lineage, yielded increased levels of LTB4 whereas the non-enzymatic isomers of this compound, i.e. Δ6-trans-LTB4 and 12-epi-Δ6-trans-LTB4, declined. In addition, the sum of LTB4 and its non-enzymatically formed isomers increased in mixed cultures of monocytes and monoclonal lymphocytic cells as compared to monocytes alone.
The present study indicates that activated monocytes release LTA4, which is converted into LTB4 by monoclonal lymphocytic cells. Furthermore, the increase of the total amounts of leukotrienes on incubation of monocytes with lymphocytic cells, suggests the presence of an additional mechanism leading to activation of the 5-lipoxygenase pathway in monocytes.
12(R)-Hydroxy-5,8,10,14-eicosatetraenoic acid [12(R)-HETE], a cytochrome P450 arachidonate metabolite, is metabolized by corneal tissues via three distinct metabolic pathways: beta-oxidation, omega-hydroxylation, and keto-reduction. The major metabolite released from the intact rabbit corneal epithelium or cultured cells was identified by mass spectrometric analysis as 8-hydroxy-4,6,10-hexadecatrienoic acid, the tetranor metabolite derived following two steps of beta-oxidation from the carboxy terminus. The beta-oxidation pathway was expressed in both microsomes and mitochondria isolated from bovine corneal epithelium and was dependent on the addition of oxidizing equivalents. The major metabolite of 12(R)-HETE in subcellular fractions of bovine corneal epithelial cells was a dihydro compound, 12-hydroxy-5,8,14-eicosatrienoic acid (12-HETrE). This derivative is presumably formed by an oxidation of the hydroxyl group followed by two keto-reduction steps, since its formation was accompanied by the appearance of a keto metabolite identified as 12-oxo-5,8,14-eicosatrienoic acid. The omega-hydroxylation, in contrast to other cell types, was a minor route for 12(R)-HETE metabolism in these tissues. Since 12(R)-HETE has been implicated as a modulator of Na(+)-K(+)-ATPase activity and its related functions in ocular tissues, these findings raise the possibility that the newly described metabolites may be involved in regulating corneal functions. In addition, the presence of a keto reductase in the cornea may be of great importance following injury since 12(R)-HETrE resulting from 12(R)-HETE by this activity is a potent ocular proinflammatory compound.
1. Leukotrienes (LTs) are potent pro-inflammatory mediators with actions relevant to the pathophysiology of cystic fibrosis (CF), including increased mucus production, bronchoconstriction, leucocyte chemotaxis, and increased vascular permeability. We have therefore investigated the potential role of LTs in children with CF. Leukotriene E4 levels were assessed in the urine of 30 normal (N) children (aged 1.3-12.7 years) and 30 CF children (1.6-14.3 years). Sputum from 13 of the CF children was analysed from LTB4, LTC4, LTD4, and LTE4. LTs were separated by reversed-phase h.p.l.c. and quantitated by radioimmunoassay. 2. Urinary LTE4 levels were log normally distributed, with geometric mean values (95% confidence intervals) of N: 88.4 (71.3-111) pmol mmol-1 creatinine (n = 30), and CF: 112 (70.6-177) pmol mmol-1 creatinine (n = 30; P greater than 0.05). Of the CF subjects, 33% had urinary LTE4 levels above 200 pmol mmol-1 creatinine, compared with 3.3% of the N children. 3. In sputum, mean (+/- s.e. mean) LT concentrations were (pmol g-1), LTB4: 44.3 +/- 10.8, LTC4: 4.9 +/- 1.3, LTD4: 1.8 +/- 0.9, and LTE4: 67.7 +/- 18.9 (n = 13). 4. Urinary LTE4 levels correlated significantly with sputum LTE4 levels (r = 0.673, P = 0.012), and with sputum levels of total cysteinyl-LTs (r = 0.660, P = 0.014). 5. In conclusion, total cysteinyl-LT content in sputum is 10-fold higher than previously reported, consisting primarily (91%) of LTE4. The high levels of LTE4 and LTB4 in sputum suggest involvement of LTs in the pathophysiology of CF. Urinary LTE4 levels may prove useful as a marker for cysteinyl-LT production in sputum.
12(R)-HETE [12(R)-hydroxy-5, 8, 10, 14 eicosatetraenoic acid] is one of the major arachidonic acid metabolites produced by microsomal cytochrome P450 of the corneal epithelium. This metabolite is a potent inhibitor of Na(+)-K(+)-ATPase activity in several tissues. We investigated endogenous production of 12(R)-HETE in the rabbit corneal epithelium. Incubation of corneal epithelial sheets (prelabeled with 14C-arachidonic acid) with arginine vasopressin resulted in the production of radioactive 12(R)-HETE suggesting its formation from endogenously labeled-arachidonic acid. The maximal response was obtained with 1 microM arginine vasopressin and represents a 15-fold increase in 12(R)-HETE formation compared with that of control tissues. Stimulation of 14C-arachidonic acid release with a detergent, digitonin, also resulted in endogenous 12(R)-HETE formation. Analysis of the incubation media following digitonin treatment of prelabeled corneal epithelial sheets revealed that 12(R)-HETE production was maximal at 20 microM digitonin, a 17-fold increase over control values. This study is the first to describe hormonal and traumatic stimulation of 12(R)-HETE formation from endogenously labeled arachidonic acid in intact corneal tissues. This study demonstrates that the formation of this Na(+)-K(+)-ATPase inhibitor can be modulated by physiological and pathophysiological regulation.
Leukotriene B4 (LTB4) is a pro-inflammatory arachidonate metabolite. We have characterized the LTB4 receptors in sheep lung membranes and have assessed the contribution of the guanine-nucleotide-binding (G) protein in the regulation of receptor affinity states. Saturation isotherms have demonstrated a single class of LTB4 receptor with a Kd of 0.18 +/- 0.03 nM and a density (Bmax.) of 410 +/- 84 fmol/mg of protein in sheep lung membranes. The effect of the G-protein on receptor affinity was assessed in the presence of non-hydrolysable GTP analogues (e.g. GTP[S]) and in membranes following alkali treatment (pH 12.1) to remove the G-protein. Saturation isotherms produced either in the presence of GTP[S] (Kd.GTP[S] = 0.51 +/- 0.02 nM) or with alkali-treated membranes (Kd.alk. = 0.52 +/- 0.02 nM) demonstrated a 3-fold shift in receptor affinity for [3H]LTB4 binding. In competition experiments, the rank order of affinity of LTB4 analogues was LTB4 greater than 20-OH-LTB4 greater than trans-homo-LTB4 greater than 6-trans-LTB4 greater than 20-COOH-LTB4, using either untreated or alkali-treated membranes, both in the presence and absence of GTP[S]. These findings demonstrate that, in sheep lung membranes, there is only one class of LTB4 receptor. Removal of the G-protein or uncoupling of the receptor from the G-protein shifted the agonist-binding affinity of the receptor by 3-4-fold, without affecting the specificity of the LTB4 receptor in either the high- or the low-affinity state.
Production of LTC4 and LTB4 by eosinophils and neutrophils was compared between nine asymptomatic asthmatic subjects and eight healthy donors. We observed a statistically significant difference in LTC4 generated by eosinophils, but not LTB4 produced by neutrophils. These findings suggest a quantitative difference in eosinophils between asthmatic subjects and healthy donors.
The synthesis, binding and photoincorporation of a thromboxane A2/prostaglandin H2 (TXA2/PGH2) analog (9,11-dimethylmethano-11,12-methano-16-(3-[125I]iodo-4-azidophenyl )-13,14- dihydro-13-aza-15 alpha beta-omega-tetranor-TXA2) [( 125I]PTA-Azido) to washed human platelets was characterized. Kinetic analysis of the binding of [125I]PTA-Azido at 30 degrees C yielded a k1 of 1.83.10(7) M-1.min-1 and k -1 of 0.195 min-1, Kd = k -1/k1 = 11 nM. Incubation of washed human platelets with [125I]PTA-Azido followed by photolysis resulted in the radiolabelling of a number of platelet proteins as assessed by SDS-PAGE autoradiography. The radiolabelling of three of these protein bands could be either uniformly blocked or reduced with a series of structurally dissimilar TXA2/PGH2 receptor antagonists or agonists and corresponded to proteins with a molecular mass of 43, 39 and 27 kDa. In addition, the incorporation of [125I]PTA-Azido into the three proteins was stereoselectively blocked by a pair of optically active stereoisomers that are TXA2/PGH2 receptor antagonists. Two-dimensional gel electrophoresis indicated that the 43 kDa protein possessed a pI value of 5.6 and that the 27 kDa protein exists in at least three isoforms with pI values of 4.9, 5.1 and 5.3. The labelling pattern was not altered by a mixture of proteinase inhibitors. The data suggest that one or more of these specifically radiolabelled proteins may represent the human platelet TXA2/PGH2 receptor.
As a model to perhaps better indicate potential in vivo tissue inflammatory events, the generation of leukotriene (LT)B4, 20-OH-LTB4, sulfidopeptide LT, and platelet-activating factor (PAF) from human whole blood stimulated with zymosan was compared with that produced by isolated human neutrophils suspended either in buffer or plasma. Several reports have shown that substantial LTB4 biosynthesis could be induced after addition of zymosan to whole blood, but little was known concerning the generation of other important lipid mediators, or the cellular source of these. We have shown that, in spite of some subject variation, the zymosan-induced production of 20-OH-LTB4, LTB4, and LTE4 reached maxima within 30 to 60 min with 1.1, 2.8, and 0.60 ng/10(6) neutrophils, respectively. These concentrations would be sufficient to induce significant biologic effects. Studies with isolated cell mixtures suggested that the neutrophil was the primary source of the lipid mediators or their precursors in this system, although a number of other cell types contributed as accessory cells to the final amounts and mix of mediators produced. The ratio of neutrophils to accessory cells in mixed cell experiments dramatically modified the metabolic pattern of leukotriene generation. The concentration of LTB4 was increased in the presence of RBC and that of LTE4 when platelets were present. These results suggested that cellular cooperation and transcellular biosynthesis played a key role in the overall production of eicosanoids such as LTB4 and LTC4. The concomitant synthesis of PAF in isolated cells and in whole blood was also determined as another member of the complex lipid mediator network. Maximal production of cell-associated PAF was observed within 30 min after the initiation of phagocytosis and reached levels of 3 to 5 ng PAF/10(6) neutrophils. When other cells were present in a coincubation system, the time course for production of PAF was not altered, but maximal concentration of PAF was lower, perhaps as a result of enhanced PAF metabolism. Study of eicosanoids and other lipid mediator production in mixed cell populations provides insight into those events occurring within tissues, where cross-cell signaling and transcellular biosynthesis may occur.
L-670,596 ((-)6,8-difluoro-9-rho-methylsulfonyl benzyl-1,2,3,4- tetrahydrocarbazol-1-yl-acetic acid) has been shown to be a potent receptor antagonist as evidenced by the inhibition of the binding of 125I-labeled PTA-OH to human platelets (IC50, 5.5 x 10(-9) M), inhibition of U-44069 induced aggregation of human platelet rich plasma (IC50, 1.1 x 10(-7) M), and competitive inhibition of contractions of the guinea pig tracheal chain induced by U-44069 (pA2,9.0). The compound was also active in vivo as shown by inhibition of arachidonic acid and U-44069 induced bronchoconstriction in the guinea pig (ED50 values, 0.04 and 0.03 mg/kg i.v., respectively), U44069 induced renal vasoconstriction in the pig (ED50, 0.02 mg/kg i.v.), and inhibition of ex vivo aggregation of rhesus monkey platelets to U-44069 (active 1-5 mg/kg p.o.). The selectivity of the compound was indicated by the failure to inhibit, first, ADP-induced human or primate platelet aggregation and, second, bronchoconstriction in the guinea pig in vivo and contraction of the guinea pig tracheal chain in vitro to a variety of agonists. It is concluded that L-670,596 is a potent, selective, orally active thromboxane A2/prostaglandin endoperoxide receptor antagonist.
The in vivo pharmacology of ICI 198,615, a highly potent and selective peptide leukotriene (LT) receptor antagonist, is described. In a conscious guinea pig model, ICI 198,615 provided dose-related antagonism of aerosol LTD4-induced dyspnea when administered p.o., i.v. or by aerosol. The pharmacologic half-lives of ICI 198,615 by these routes of administration were greater than 16 hr, 68 min and 34 min, respectively. In pulmonary mechanics studies in which the effects of i.v. or aerosol administration of LTC4 and LTD4 on pulmonary resistance (Rp) or dynamic lung compliance (Cdyn) could be quantitated, ICI 198,615 provided dose-related antagonism when administered p.o., i.d, i.v. or by aerosol. The compound also antagonized LTE4-induced changes in Rp and Cdyn when administered i.v. ICI 198,615 reversed the effect of LTC4, LTD4 and LTE4 on Rp, as well as the effect of LTC4 and LTE4 on Cdyn. The compound was less able to reverse the effect of LTD4 on Cdyn. These results indicate that ICI 198,615 possesses an in vivo profile which is consonant with utility in the treatment of allergic diseases.
Human platelets dose-dependently converted exogenous leukotriene A4 to leukotriene C4 and efficiently metabolized this compound to leukotrienes D4 and E4. Neither of these compounds were produced after stimulation of human platelet suspensions with ionophore A23187. After LTA4 incubation of subcellular fractions, formation of leukotriene C4 was exclusively observed in the particulate fraction and was separable from the classical glutathione S-transferase activity. This suggested the presence of a specific leukotriene C4 synthase in human platelets. Addition of physiological amounts of autologous platelets to human granulocyte suspensions significantly increased ionophore A23187-induced formation of leukotriene C4. In contrast, the production of leukotriene B4 was decreased. After preincubation of platelets with [35S]cysteine, 35S-labeled leukotriene C4 was produced by A23187-stimulated platelet-granulocyte suspensions, strongly indicating a transcellular biosynthesis of this compound.
Sulfasalazine and, to a lesser extent, 5-aminosalicylic acid and N-acetyl-aminosalicylic acid, were found to block production of 5-hydroxy-6,8,11,14-eicosatetraenoic acid, leukotriene B4 (LTB4), and LTB4 stereoisomers from both exogenous and endogenous [14C]arachidonic acid (14C-AA) in ionophore A23187 (1 microgram/ml)-stimulated human neutrophils. Lipids were assessed by thin-layer chromatography and reverse-phase high-pressure lipid chromatography. Sulfasalazine blocked the synthesis of these metabolites from both exogenous and endogenous AA, but was more effective in blocking the metabolism of exogenous than endogenous AA. The IC50 for sulfasalazine in blocking the synthesis of LTB4 was 0.8 mM when exogenous AA was the substrate and 2.8 mM when endogenous AA was the substrate. N-Acetyl-aminosalicylic acid showed a similar pattern, but was less effective than sulfasalazine (IC50 for exogenous AA was 5.4 mM, and for endogenous AA was 8.0 mM). 5-Aminosalicylic acid had similar effects with an IC50 of 6.0 and 6.4 mM respectively. Sulfasalazine but not 5-aminosalicylic acid inhibited the incorporation of arachidonic acid into phospholipids and triglycerides. Sulfasalazine, but not its metabolites, inhibited the release of 14C-AA from membrane phospholipids in a dose-dependent manner (46.0% inhibition with 4 mM sulfasalazine). Sulfasalazine also blocked the metabolism of exogenously added LTB4 to 20-OH LTB4 and 20-COOH LTB4 with an IC50 of 2 mM. Our findings suggest that under physiologic conditions, with endogenous AA as a substrate, sulfasalazine acts as an inhibitor of lipoxygenase, of phospholipase A2 and of LTB4 metabolism, whereas 5-aminosalicylic acid and N-acetyl-aminosalicylic acid inhibit only lipoxygenase.
Chemoattractant arachidonate lipoxygenase products have been recovered from the skin lesions of psoriasis, and may play a role in eliciting the intra-epidermal neutrophil infiltrate that characterises this disease. In view of evidence for lipoxygenase activity in psoriasis, the characteristic vasodilation in psoriatic lesions, and the vasodilator properties of leukotriene (LT) C4 and D4 in human skin, the presence of these LTs in psoriatic lesions has been investigated. Skin chamber fluid from abraded psoriatic lesions contained significantly greater amounts of immunoreactive material than that from clinically normal skin, as determined by a double antibody radioimmunoassay (RIA) that uses antiserum cross-reacting with both LTC4 and LTD4. Purification of lesional chamber fluid and scale extracts by high performance liquid chromatography (HPLC) and RIA of fractions showed immunoreactivity which co-eluted with standard LTC4 and LTD4. These findings suggest that LTC4 and LTD4 may play a role in mediating the vasodilation and increased blood flow that characterise psoriatic skin lesions.
Leukotrienes in psoriatic skin lesions are potent mediators of inflammation. We have studied the capacity of leukotrienes to stimulate the DNA synthesis of cultured human epidermal keratinocytes. At concentrations ranging from 10(-12) to 10(-8) M, LTB4 produced a 100% increase of DNA synthesis determined both as the incorporation of [3H] thymidine and as the labelling index. In comparison, LTB4 had no effect on the DNA synthesis of dermal fibroblast cultures. 5S,12S-LTB4 and 5S,12S-all-trans-LTB4 did not change the DNA synthesis of keratinocytes, but the effect of LTB4 was abolished in the presence of 5S,12S-all-trans HLTB4. Being less potent than LTB4 the peptidoleukotrienes (LTC4, LTD4) also stimulated keratinocyte DNA synthesis. The effect of the peptidoleukotrienes, but not of LTB4, was antagonized by FPL 55712. These results show that leukotrienes B4, C4 and D4 exert potent and stereospecific mitogenic effects on cultured human keratinocytes. The presence of these arachidonic acid metabolites in psoriatic skin lesions may be pertinent to both inflammation and aberrant epidermal growth in psoriasis.
Purified human eosinophils were challenged with N-formyl-methionyl-leucyl-phenylalanine, leukotriene B4, platelet-activating-factor, valyl-glycyl-seryl-glutamic acid, phorbol myristate acetate, zymosan, opsonized zymosan and the calcium ionophore A23187 to induce leukotriene synthesis. Reversed-phase high performance liquid chromatography analysis demonstrated the almost exclusive synthesis of leukotriene C4 by eosinophils of 11 healthy donors after challenge with opsonized zymosan [(22 +/- 4) X 10(6) molecules LTC4/cell, mean +/- SE] or the calcium ionophore A23187 [(54 +/- 7) X 10(6) molecules LTC4/cell, mean +/- SE]. The other agents were not capable of inducing leukotriene formation. When in addition to opsonized zymosan N-formyl-methionyl-leucyl-phenylalanine or platelet-activating factor were added a significant increase of the leukotriene C4 synthesis by eosinophils was observed. These results suggest that eosinophils might be triggered to produce considerable amounts of the spasmogenic leukotriene C4 in vivo by C3b- and/or IgG-mediated mechanisms e.g. phagocytosis.