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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.
... In our previously published work [7], the fatty acids and fatty acid conjugates family was the most highly significantly expressed for both polar and nonpolar metabolites in plasma from obese mice [7]. Eicosanoids are highly bioactive fatty acid metabolites, and a subset of essential polyunsaturated fatty acids (PUFAs) provides the substrates for their synthesis [17,18]. Using the METLIN-annotated metabolic features shown in Supplemental Tables S3 and S4, the entire linoleic acid elongation and desaturation pathway was downregulated in NGOB vs. WT plasma: in most cases, with statistical significance ( Figure 7A, left, gray vs. black bars). ...
... In our previously published work [7], the fatty acids and fatty acid conjugates family was the most highly significantly expressed for both polar and nonpolar metabolites in plasma from obese mice [7]. Eicosanoids are highly bioactive fatty acid metabolites, and a subset of essential polyunsaturated fatty acids (PUFAs) provides the substrates for their synthesis [17,18]. Using the METLIN-annotated metabolic features shown in Supplemental Tables S3 and S4, the entire linoleic acid elongation and desaturation pathway was downregulated in NGOB vs. WT plasma: in most cases, with statistical significance (Fig-Figure 6. Volcano plots used to determine significantly differentially expressed annotated metabolic features (left) and heat maps created by unsupervised hierarchical clustering using the top 25 most highly differentially expressed of these (right) in pairwise comparisons of (A) NGOB vs. WT plasma samples and (B) T2D vs. NGOB plasma samples. ...
The transition from β-cell compensation to β-cell failure is not well understood. Previous works by our group and others have demonstrated a role for Prostaglandin EP3 receptor (EP3), encoded by the Ptger3 gene, in the loss of functional β-cell mass in Type 2 diabetes (T2D). The primary endogenous EP3 ligand is the arachidonic acid metabolite prostaglandin E2 (PGE2). Expression of the pancreatic islet EP3 and PGE2 synthetic enzymes and/or PGE2 excretion itself have all been shown to be upregulated in primary mouse and human islets isolated from animals or human organ donors with established T2D compared to nondiabetic controls. In this study, we took advantage of a rare and fleeting phenotype in which a subset of Black and Tan BRachyury (BTBR) mice homozygous for the Leptinob/ob
mutation-a strong genetic model of T2D-were entirely protected from fasting hyperglycemia even with equal obesity and insulin resistance as their hyperglycemic littermates. Utilizing this model, we found numerous alterations in full-body metabolic parameters in T2D-protected mice (e.g., gut microbiome composition, circulating pancreatic and incretin hormones, and markers of systemic inflammation) that correlate with improvements in EP3-mediated β-cell dysfunction.
... 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.
... In addition to metalloproteinases, they 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 in daily dermatolgical practice are: phototoxicity, hyperpigmentation, onycholysis, photoonycholysis, induced lupus erythematosus, idiopathic intracranial hypertension. In this article, we summarize the use of tetracyclines in infectious diseases and inflammatory dermatoses, and further discuss indications where the efficacy and safety of tetracyclines have been highlighted over the past few years.
... AA is primarily metabolized through three major pathways, mediated by the activity of cyclooxygenase (COX), lipoxygenase (LOX), and cytochrome P450 (CYP) enzymes ( Figure 1). All three pathways generate eicosanoids (20 carbon fatty acids), which play a role in many biological processes including inflammation [11], immune function [12,13], vascular function [14], and pain perception [15]. This review will focus on the enzymes that metabolize AA in each of these pathways as well as the metabolites generated and their effects on beta-cell mass and function. ...
Arachidonic acid (AA) is a polyunsaturated 20-carbon fatty acid present in phospholipids in the plasma membrane. The three primary pathways by which AA is metabolized are mediated by cyclooxygenase (COX) enzymes, lipoxygenase (LOX) enzymes, and cytochrome P450 (CYP) enzymes. These three pathways produce eicosanoids, lipid signaling molecules that play roles in biological processes such as inflammation, pain, and immune function. Eicosanoids have been demonstrated to play a role in inflammatory, renal, and cardiovascular diseases as well type 1 and type 2 diabetes. Alterations in AA release or AA concentrations have been shown to affect insulin secretion from the pancreatic beta cell, leading to interest in the role of AA and its metabolites in the regulation of beta-cell function and maintenance of beta-cell mass. In this review, we discuss the metabolism of AA by COX, LOX, and CYP, the roles of these enzymes and their metabolites in beta-cell mass and function, and the possibility of targeting these pathways as novel therapies for treating diabetes.
... Arachidonic acid gives origin to PGs, thromboxanes, and leukotrienes, through the action of the enzymes COX and LOX, and these potent molecules will exert their effect by binding to specific membrane and nuclear receptors. 16 Therefore these enzymatic systems are also seen as important targets for the development of antiinflammatory agents. ...
Cyanobacteria depend on solar radiation for photosynthesis and have, since ancient times, developed different strategies to cope with the damaging radiation in the UV range. Among these, the production of small molecules that act as UV filters has been thoroughly investigated for these organisms. Two major families of UV filters are produced by cyanobacteria—scytonemins and mycosporine-like amino acids. Here, we present an overview of the diversity, distribution, structural features, and UV protective properties of these metabolites. We also provide an account of their associated biological activities and biotechnological potential. Finally, we look into how these valuable small molecules can be accessed, namely, their biological sources, their biosynthesis and heterologous expression, as well as synthetic routes that have been developed to access these scaffolds. Finally, we briefly cover additional cyanobacterial compounds that have unique UV-radiation absorbing chromophores.
Keywords: UV-A; UV-B; scytonemin; MAAs; biosynthesis; sunscreens
... In mammals eicosanoid biosynthesis is believed to be promoted by the activity of phospholipase A2 (PLA2), which cleaves fatty acids to release arachidonic acid (AA). The released AA is used to synthesize eicosanoids via three pathways: the cyclooxygenase (COXs) pathway, which generate prostaglandins (PGs) and thromboxanes (TXs); the lipoxygenase (LOX) pathway, which enables the production of leukotrienes (LTs), lipoxins (LXs) and hydroxyeicosatetraenoic acids (HETEs) and hydroperoxyeicosatetraenoic acids (HPETEs); as well as the cytochrome P450 pathway, which enables the generation of PGs, TXs, HETEs, HPETEs and epoxyeicosatrienoic acids (EETEs) (Khanapure et al., 2007;Haeggstrom and Funk, 2011). ...
Apoptosis and autophagy, the mechanisms of programmed cell death, play critical roles in physiological and pathological processes in both vertebrates and invertebrates. Apoptosis is also known to play an important role in the immune response, particularly in the context of entomopathogenic infection. Of the factors influencing the apoptotic process during infection, two of the lesser known groups are caspases and eicosanoids. The aim of this study was to determine whether infection by the entomopathogenic soil fungus Conidiobolus coronatus is associated with apoptosis and changes in caspase activity in the hemocytes of Galleria mellonella larvae, and to confirm whether fungal infection may affect eicosanoid levels in the host. Larvae were exposed for 24 h to fully grown and sporulating fungus. Hemolymph was collected either immediately after termination of exposure (F24 group) or 24 h later (F48 group). Apoptosis/necrosis tests were performed in hemocytes using fluorescence microscopy and flow cytometry, while ELISA tests were used to measure eicosanoid levels. Apoptosis and necrosis occurred to the same degree in F24, but necrosis predominated in F48. Fungal infection resulted in caspase activation, increased PGE1, PGE2, PGA1, PGF2α, and 8-iso-PGF2α levels and decreased TXB2 levels, but had no effect on TXA2 or 11-dehydro-TXB2 concentrations. In addition, infected larvae demonstrated significantly increased PLA2 activity, known to be involved in eicosanoid biosynthesis. Our findings indicate that fungal infection simultaneously induces apoptosis in insects and stimulates general caspase activity, and this may be correlated with changes in the concentrations of eicosanoids.
... Combining proteomic with metabolomic profiling is especially attractive, since it may support a functional interpretation of the involved pathways. In addition, signaling lipids are key players during inflamation and act in a concerted fashion with proteins [36,37]. Thus, we have applied an in-depth proteome, metabolome and eicosanoid profiling of the endometriotic epithelial cell line 12-Z to investigate and characterize their responsiveness towards inflammatory signals. ...
Endometriosis is a benign disease affecting one in ten women of reproductive age worldwide. Although the pain level is not correlated to the extent of the disease, it is still one of the cardinal symptoms strongly affecting the patients’ quality of life. Yet, a molecular mechanism of this pathology, including the formation of pain, remains to be defined. Recent studies have indicated a close interaction between newly generated nerve cells and macrophages, leading to neurogenic inflammation in the pelvic area. In this context, the responsiveness of an endometriotic cell culture model was characterized upon inflammatory stimulation by employing a multi-omics approach, including proteomics, metabolomics and eicosanoid analysis. Differential proteomic profiling of the 12-Z endometriotic cell line treated with TNFα and IL1β unexpectedly showed that the inflammatory stimulation was able to induce a protein signature associated with neuroangiogenesis, specifically including neuropilins (NRP1/2). Untargeted metabolomic profiling in the same setup further revealed that the endometriotic cells were capable of the autonomous production of 7,8-dihydrobiopterin (BH2), 7,8-dihydroneopterin, normetanephrine and epinephrine. These metabolites are related to the development of neuropathic pain and the former three were found up-regulated upon inflammatory stimulation. Additionally, 12-Z cells were found to secrete the mono-oxygenated oxylipin 16-HETE, a known inhibitor of neutrophil aggregation and adhesion. Thus, inflammatory stimulation of endometriotic 12-Z cells led to specific protein and metabolite expression changes suggesting a direct involvement of these epithelial-like cells in endometriosis pain development.
... COX activity is the rate-limiting step for the conversion of arachidonic acid (AA) to prostaglandins (PGs) and other metabolites that act as key regulators of airway cellular physiology (Laporte et al., 1999). COX-1 is expressed constitutively, whereas COX-2 is inducible and becomes elevated in several inflammatory conditions, including chronic airway diseases such as asthma (Khanapure et al., 2007;Pang et al., 1998;Torres et al., 2008;Wenzel, 1997). Furthermore, the prostanoid metabolism pathway is very complex and involves the release of a variety of mediators, which induce different signaling in various effector cells, thereby regulating pathophysiological outcomes in diseases. ...
Diacylglycerol kinase (DGK), a lipid kinase, catalyzes the conversion of diacylglycerol (DAG) to phosphatidic acid, thereby terminating DAG-mediated signaling by Gq-coupled receptors that regulate contraction of airway smooth muscle (ASM). A previous study from our laboratory demonstrated that DGK inhibition or genetic ablation leads to reduced ASM contraction and provides protection for allergen-induced airway hyperresponsiveness. However, the mechanism by which DGK regulates contractile signaling in ASM is not well established. Herein, we investigated the role of prorelaxant cAMP-protein kinase A (PKA) signaling in DGK-mediated regulation of ASM contraction. Pretreatment of human ASM cells with DGK inhibitor I activated PKA as demonstrated by the phosphorylation of PKA substrates, VASP, Hsp20, and CREB, which was abrogated when PKA was inhibited pharmacologically or molecularly using overexpression of the PKA inhibitor peptide, PKI. Furthermore, inhibition of DGK resulted in induction of cyclooxygenase (COX) and generation of prostaglandin E2 (PGE2) with concomitant activation of Gs-cAMP-PKA signaling in ASM cells in an autocrine/paracrine fashion. Inhibition of protein kinase C (PKC) or extracellular-signal-regulated kinase (ERK) attenuated DGK-mediated production of PGE2 and activation of cAMP-PKA signaling in human ASM cells, suggesting that inhibition of DGK activates the COX-PGE2 pathway in a PKC-ERK-dependent manner. Finally, DGK inhibition-mediated attenuation of contractile agonist-induced phosphorylation of myosin light chain 20 (MLC-20), a marker of ASM contraction, involves COX-mediated cAMP production and PKA activation in ASM cells. Collectively these findings establish a novel mechanism by which DGK regulates ASM contraction and further advances DGK as a potential therapeutic target to provide effective bronchoprotection in asthma.
... Eicosanoid levels are known to increase in response to inflammatory stimuli in the lungs [119], and PMN infiltration into the pulmonary space is a hallmark feature of pneumococcal pneumonia. While PMN activity is imperative to innate immunity, uncontrolled inflammation can result in tissue destruction and lung disease. ...
Lipoxygenases (LOXs) are lipid metabolizing enzymes that catalyze the di-oxygenation of polyunsaturated fatty acids to generate active eicosanoid products. 12-lipoxygenases (12-LOXs) primarily oxygenate the 12th carbon of its substrates. Many studies have demonstrated that 12-LOXs and their eicosanoid metabolite 12-hydroxyeicosatetraenoate (12-HETE), have significant pathological implications in inflammatory diseases. Increased level of 12-LOX activity promotes stress (both oxidative and endoplasmic reticulum)-mediated inflammation, leading to damage in these tissues. 12-LOXs are also associated with enhanced cellular migration of immune cells—a characteristic of several metabolic and autoimmune disorders. Genetic depletion or pharmacological inhibition of the enzyme in animal models of various diseases has shown to be protective against disease development and/or progression in animal models in the setting of diabetes, pulmonary, cardiovascular, and metabolic disease, suggesting a translational potential of targeting the enzyme for the treatment of several disorders. In this article, we review the role of 12-LOXs in the pathogenesis of several diseases in which chronic inflammation plays an underlying role.
... Higher levels of LTB4 and PGs have been reported in the joints of the patients with OA and LTB4 is thought to mediate the cartilage damage. 6,7 Enzymes like cyclooxygenase (COX) and lipoxygenase (LOX), with cytochrome P450 (CYP) pathways, are associated with the arachidonic acid (ARA) pathway. [8][9][10][11] The higher levels of leukotrineB4 (LTB4) and prostaglandins (PGs) have been reported in the joints of the patients with OA wherein LTB4 is thought to mediate the cartilage damage. ...
Osteoarthritis is a progressive joint disease associated with aging in elderly is, characterized by pain, inflammation, and difficulty in movement. The pathways involved in the progression of this disease remain unclear. The mediators, eicosanoids and leukotrienes are produced by COX-1/COX-2 or 5-LOX. Physicians have always used nonsteroidal anti-inflammatory drugs to treat the pain associated with osteoarthritis. A competitive inhibitor of LOX-5 and COX-2 that has both analgesic and anti-inflammatory activity is licofelone; one of the most promising candidates for the treatment of osteoarthritis is under clinical trial in treatment. A significant reduction in cartilage volume was displayed. A significant improvement over baseline on the WOMAC index and GI tolerance was also observed. Improving the symptoms related pain sensation with a happier life. With new strategies in OA, new methods to target pain, inflammation and movement restrictions would be the ultimate goal in patient satisfaction for the future. Licofelone was found to be effective compared to NSAIDs or coxibs in the treatment of OA. Does this mean this could be the answer?
... Its activation leads to the hydrolysis of the sn-2 fatty acid substituent from membrane glycerophospholipids [11][12][13][14][15][16] to yield a free fatty acid (e.g., arachidonic acid, eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA)) and a 2-lysophospholipid [17]. Subsequent metabolism of arachidonic acid by cyclooxygenases (COX), lipoxygenase (LOX), and cytochrome P450 (CYP) pathways leads to the generation of bioactive oxidized eicosanoids, several of which are proinflammatory [18] and recognized contributors to inflammatory diseases [19][20][21][22][23][24][25][26][27]. Some of the most potent inflammatory eicosanoids [21] are prostaglandin E 2 (PGE 2 ), leukotrienes (LTs), hydroxyeicosatetraenoic acids (HETEs), and dihydroxyeicosatetraenoic acids (DHETEs), and they contribute to inflammation and autoimmune diseases [22]. ...
The Ca2+-independent phospholipase A2β (iPLA2β) is a member of the PLA2 family that has been proposed to have roles in multiple biological processes including membrane remodeling, cell proliferation, bone formation, male fertility, cell death, and signaling. Such involvement has led to the identification of iPLA2β activation in several diseases such as cancer, cardiovascular abnormalities, glaucoma, periodontitis, neurological disorders, diabetes, and other metabolic disorders. More recently, there has been heightened interest in the role that iPLA2β plays in promoting inflammation. Recognizing the potential contribution of iPLA2β in the development of autoimmune diseases, we review this issue in the context of an iPLA2β link with macrophages and T-cells.
... COX-2 is an inducible enzyme, which is either absent or expressed slightly in most cells [11]. However, when cells are stimulated by pro-inflammatory cytokines or cancer-promoting factors, COX-2 shows upregulation and participates in inflammation as well as the formation and development of tumors [12,13]. Studies have shown that COX-2 is involved in CP [14,15], and inhibition of COX-2 suppresses the proliferation of prostatic epithelial cells in CNP [16]. ...
Background: Chronic non-bacterial prostatitis (CNP) is a widespread disease of the male reproductive system. MiR-181c can be expressed in prostate tissue, but it has not been reported in CNP. This study aims to investigate the role of miR-181c in CNP and its mechanism of action on CNP, providing new ideas for the treatment and diagnosis of CNP. Methods: Quantitative real-time polymerase chain reaction (qRT-PCR) and western blotting were applied to determine miR-181c expression in clinical CP patients, CNP rats, and LPS-induced human prostaglandin epithelial cell RWPE-1. Then, luciferase reporter assay was performed to verify the targeting relation between miR-181c and COX-2. Through cell transfection experiments, the effect of mi-181c on the expression of COX2 and PGE2 was studied, and the effect of miR-181c/COX-2 on the proliferation of prostate epithelial cells was also explored. Results: qRT-PCR and Western blotting analysis revealed that miR-181c was low expressed in prostate tissue of CP patients and CNP rats and human prostaglandin epithelial cell RWPE-1. The luciferase reporter assay confirmed the targeting relation between miR-181c and COX-2. And miR-181c overexpression reduced the expression of COX-2 and PGE2 and suppressed the proliferation of prostate epithelial cells. COX-2 up-regulation reversed these effects caused by overexpression of miR-181c. Conclusions: miR-181c inhibited the proliferation of prostate epithelial cells through negatively regulating COX-2 to alleviate chronic non-bacterial prostatitis. Keywords: Chronic non-bacterial prostatitis, miR-181c, COX-2, prostatic epithelial cell, proliferation
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.
Cyanobacteria are among the most successful and ancient forms of life ever known. These photosynthetic autotrophs have been studied for decades as model organisms in various aspects, from photosynthesis to biotechnological applications and, more recently, for their pharmacological potential in umpteen fields. In fact, cyanobacteria are now recognized as top metabolic producers of a huge number of bioactive compounds with medical interest and that can revolutionize drug discovery and development. Allied to their metabolic capabilities, cyanobacteria benefit from a cost-effective energy-capturing ability, and high cultivation yields with minimum nutritional requirements, being extremely attractive in terms of industrial-scale production processes. This book was designed to bring together fields in which cyanobacteria derived compounds most stood out, with a special focus on those related to therapeutics, cosmetics, and nutrition, emphasizing unique molecules not found in higher organisms. Of the most promising compounds isolated so far, those acting as anti-inflammatories, anti-carcinogens, antimicrobials, and UV protectors fill a prominent place within drug discovery programs. The metabolic richness of cyanobacteria has also been upholding their key role in the field of cosmetics and nutraceuticals, with the last occupying a prominent place in a rapidly expanding market. Apart from the pharmacological and biotechnological approach, this book does not set aside the well-known cyanobacterial toxins, warning to their substantial economic and social impacts, and drawing attention to the urgency of fully addressing algal blooms and their systematic monitoring. Additionally, and given its extreme importance, this book provides a distinctive approach to cyanobacteria systematics, by exploring general aspects and biodiversity of these organisms to discuss trends in cyanobacterial taxonomy. Overall, The Pharmacological Potential of Cyanobacteria is intended to be a useful resource for students, researchers, and professionals working in the field of cyanobacteria, serving as a guide in the discovery, research, and application of these unique microorganisms. Graciliana Lopes, Marisa Silva and Vitor Vasconcelos
PREFACE
Cyanobacteria are among the most successful and ancient forms of life ever
known. These photosynthetic autotrophs have been studied for decades as model
organisms in various aspects, from photosynthesis to biotechnological applications
and, more recently, for their pharmacological potential in umpteen fields. In fact,
cyanobacteria are now recognized as top metabolic producers of a huge number
of bioactive compounds with medical interest and that can revolutionize drug discovery
and development. Allied to their metabolic capabilities, cyanobacteria benefit
from a cost-effective energy-capturing ability, and high cultivation yields
with minimum nutritional requirements, being extremely attractive in terms of
industrial-scale production processes.
This book was designed to bring together fields in which cyanobacteria derived
compounds most stood out, with a special focus on those related to therapeutics,
cosmetics, and nutrition, emphasizing unique molecules not found in
higher organisms. Of the most promising compounds isolated so far, those acting
as anti-inflammatories, anti-carcinogens, antimicrobials, and UV protectors fill a
prominent place within drug discovery programs. The metabolic richness of cyanobacteria
has also been upholding their key role in the field of cosmetics and
nutraceuticals, with the last occupying a prominent place in a rapidly expanding
market. Apart from the pharmacological and biotechnological approach, this book
does not set aside the well-known cyanobacterial toxins, warning to their substantial
economic and social impacts, and drawing attention to the urgency of fully
addressing algal blooms and their systematic monitoring. Additionally, and given
its extreme importance, this book provides a distinctive approach to cyanobacteria
systematics, by exploring general aspects and biodiversity of these organisms to
discuss trends in cyanobacterial taxonomy.
Overall, The Pharmacological Potential of Cyanobacteria is intended to be a
useful resource for students, researchers, and professionals working in the field of
cyanobacteria, serving as a guide in the discovery, research, and application of
these unique microorganisms.
Graciliana Lopes, Marisa Silva and Vitor Vasconcelos
Eine hohe psychische und physische Leistungsfähigkeit bis ins fortgeschrittene Alter steht bei den meisten Menschen ganz oben auf der persönlichen Wunschliste, um möglichst lange selbstständig in der gewohnten Umgebung zu leben. In den letzten 100 Jahren hat sich die mittlere Lebenserwartung der Europäer durch die moderne medizinische Versorgung und Verbesserung der Lebensbedingungen nahezu verdoppelt. Während in Deutschland zu Beginn des letzten Jahrhunderts der Anteil der über 60-Jährigen noch 5 % betrug, sind es gegenwärtig bereits nach Angaben des Statistischen Bundesamtes 26 %, und für das Jahr 2030 wird mit bis zu 36 % der Bevölkerung gerechnet, die das 60. Lebensjahr überschritten haben. Während früher über zwei Drittel der Menschen an Infektionen starben, sterben heute etwa 70 % an Alterskrankheiten (Ben-Haim et al. 2018).
Background and Purpose
Oridonin (Ori) has been shown to protect against acute liver injury (ALI) induced by D-galactosamine (D-GalN) and lipopolysaccharide (LPS). Oxylipins are oxidation products of polyunsaturated fatty acids (PUFAs) and are key proinflammatory mediators. This study aimed to investigate the changes in oxylipins in the livers of mice with D-GalN/LPS-induced ALI and the effects of Ori on these changes.
Results
54 oxylipins in liver tissues were identified and qualitatively and quantitatively analyzed by ultra-performance liquid chromatography-electrospray ionization triple quadrupole mass spectrometry (UPLC-QTRAP/MS/MS). The levels of 12-HETE, 12-HEPE, 14(S)-HDHA, PGE2, dihomo-γ-linolenic acid and 13-HOTrE in the liver were significantly increased in the D-GalN/LPS-induced ALI group compared with the control group, and the levels of EPA and 7-HDHA were significantly decreased. However, pretreatment with Ori dramatically decreased the levels of 12-HETE, 12-HEPE, 14(S)-HDHA, PGE2 and 13-HOTrE compared with those of the ALI group and induced 7-HDHA and 15-oxoETE. Moreover, Ori reduced the protein levels of COX-1, COX-2, ALOX5, ALOX12 and ALOX15 induced by D-GalN/LPS, indicating that Ori altered oxylipins through the COX and LOX pathways.
Conclusions
These results suggest that the protective effect of Ori on ALI is partly mediated by affecting the oxylipin pathway.
Arachidonic acid is metabolized by cyclooxygenase, lipoxygenase, and cytochrome P450 enzymes to produce prostaglandins, leukotrienes, epoxyeicosatrienoic acids (EETs), and hydroxyeicosatetraenoic acids (HETEs), along with other eicosanoids. Eicosanoids have important physiological and pathological roles in the body, including the cardiovascular system. Evidence from several experimental and clinical studies indicates differences in eicosanoid levels, as well as in the activity or expression levels of their synthesizing and metabolizing enzymes between males and females. In addition, there is a clear state of gender specificity in cardiovascular diseases (CVD), which tend to be more common in men compared to women, and their risk increases significantly in postmenopausal women compared to younger women. This could be largely attributed to sex hormones, as androgens exert detrimental effects on the heart and blood vessels, whereas estrogen exhibits cardioprotective effects. Many of androgen and estrogen effects on the cardiovascular system are mediated by eicosanoids. For example, androgens increase the levels of cardiotoxic eicosanoids like 20-HETE, while estrogens increase the levels of cardioprotective EETs. Thus, sex differences in eicosanoid levels in the cardiovascular system could be an important underlying mechanism for the different effects of sex hormones and the differences in CVD between males and females. Understanding the role of eicosanoids in these differences can help improve the management of CVD.
Eicosanoids are 20-carbon fatty acids, where the usual focus is the polyunsaturated analogue arachidonic acid and its metabolites. Arachidonic acid is thought primarily to derive from phospholipase A2 action on membrane phosphatidylcholine, and may be re-cycled to form phospholipid through conjugation with coenzyme A and subsequently glycerol derivatives. Oxidative metabolism of arachidonic acid is conducted through three major enzymatic routes: cyclooxygenases; lipoxygenases and cytochrome P450-like epoxygenases, particularly CYP2J2. Isoprostanes are structural analogues of the prostanoids (hence the nomenclature D-, E-, F-isoprostanes and isothromboxanes), which are produced in the presence of elevated free radicals in a non-enzymatic manner, leading to suggestions for their use as biomarkers of oxidative stress. Molecular targets for their action have yet to be defined.
The cytochrome P450 enzyme superfamily (CYP), E.C. 1.14.-.-, are haem-containing monooxygenases with a vast range of both endogenous and exogenous substrates. These include sterols, fatty acids, eicosanoids, fat-soluble vitamins, hormones, pesticides and carcinogens as well as drugs. Listed below are the human enzymes, their relationship with rodent CYP enzyme activities is obscure in that the species orthologue may not metabolise the same substrates. Some of the CYP enzymes located in the liver are particularly important for drug metabolism, both hepatic and extrahepatic CYP enzymes also contribute to patho/physiological processes. Genetic variation of CYP isoforms is widespread and likely underlies a proportion of individual variation in drug disposition. The superfamily has the root symbol CYP, followed by a number to indicate the family, a capital letter for the subfamily with a numeral for the individual enzyme. Some CYP are able to metabolise multiple substrates, others are oligo- or mono- specific.
Inflammation and Natural Products brings together research in the area of the natural products and their anti-inflammatory action in medical, nutraceutical and food products, addressing specific chronic inflammatory diseases like cancer and the mechanistic aspects of the mode of action of some key natural products. Inflammation is a complicated process, driven by infection or injury or genetic changes, which results in triggering signalling cascades, activation of transcription factors, gene expression, increased levels of inflammatory enzymes, and release of various oxidants and pro-inflammatory molecules in inflammatory cells. Excessive oxidants and inflammatory mediators have a harmful effect on normal tissue, including toxicity, loss of barrier function, abnormal cell proliferation, inhibiting normal function of tissues and organs and finally leading to systemic disorders. The emerging development of natural product formulations utilizing the unique anti-inflammatory compounds such as polyphenols, polysaccharides, terpenes, fatty acids, proteins and several other bioactive components has shown notable successes. Inflammation and Natural Products: Recent Development and Current Status provides a comprehensive resource, ranging from detailed explanation on inflammation to molecular docking strategies for naturally occurring compounds with anti-inflammatory activity. It is useful for graduate students, academic and professionals in the fields of pharmaceutical and medical sciences and specialists from natural product-related industries.
Ischemic heart disease is among the primary causes of cardiovascular-related deaths worldwide. Conventional treatments including surgical interventions and medical therapies aid in preventing further damage to heart muscle but are unable to provide a permanent solution. In recent years, stem cell therapy has emerged as an attractive alternative to restore damaged myocardium after myocardial injury. Allogeneic (donor-derived) mesenchymal stem cells (MSCs) have shown great promise in preclinical and clinical studies, making them the most widely accepted candidates for cardiac cell therapy. MSCs promote cardiac repair by modulating host immune system and secreting various soluble factors, of which prostaglandin E2 (PGE2) is an important one. PGE2 plays a significant role in regulating cardiac remodeling following myocardial injury. In this review, we provide an overview of allogeneic MSCs as candidates for myocardial regeneration with a focus on the role of the PGE2/cyclooxygenase-2 (COX2) pathway in mediating these effects.
Scope
We investigated the FADS1 rs174550 genotype interaction with dietary intakes of high linoleic acid (LA) and high alpha‐linolenic acid (ALA) on the response of fatty acid composition of plasma phospholipids (PLs), and markers of low‐grade inflammation and glucose‐insulin homeostasis.
Methods and Results
One‐hundred thirty homozygotes men for FADS1 rs174550 SNP (TT and CC genotypes) were randomized to an 8‐week intervention with either LA‐ or ALA‐enriched diet (13 E% PUFA). The source of LA and ALA were 30–50 ml of sunflower oil (SFO, 62–63 % LA) and Camelina sativa oil (CSO, 30–35 % ALA), respectively. In the SFO arm, there was a significant genotype x diet interaction for the proportion of arachidonic acid in plasma phospholipids (p<0.001), disposition index (DI30) (p = 0.039), and for serum high‐sensitive c‐reactive protein (hs‐CRP, p = 0.029) after excluding the participants with hs‐CRP concentration of >10 mg/l and users of statins or anti‐inflammatory therapy. In the CSO arm, there were significant genotype x diet interactions for n‐3 polyunsaturated fatty acids, but not for the clinical characteristics.
Conclusions
The FADS1 genotype modifies the response to high PUFA diets, especially to high‐LA diet. These findings suggest that approaches considering FADS variation might be useful in personalized dietary counseling.
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Inflammation is considered as an adaptive response to stimuli like injury or infection. But prolonged or chronic inflammation is capable of causing damage and is proved to be the trigger behind many diseases. So the mechanisms are extensively studied to get a grip on the control over them. There unveiled the multiverse of mechanisms, which raised the requirement of multitarget drugs, than “one target-one drug” concept. Synthetic drugs are invented to meet the purpose but mostly associated with considerable side effects. So the natural compounds with the multitarget approach have become the needs of the time. The current chapter discusses multiple targets involved in the inflammation events and some significant natural compounds that exhibit multitarget perspective on antiinflammatory activities.
Except for an essential step for the pathology of multiple diseases including atherosclerosis and rheumatoid arthritis, inflammation is an imperative therapeutic target for developing novel approaches for pharmacological interventions. Thus, a molecular understanding of inflammation not only provides a venue for knowledge that reveals the mechanisms of drug action and their biological targets, but also has spawned innovative maneuvers to influence multifaceted biological systems from different levels, providing new prospects for drug design and suggesting important new implications for existing clinical medicine. Meanwhile, the modulation of inflammation with the use of medicinal plants proposes an alternate to conventional therapeutic strategies for numerous ailments, particularly when suppression of inflammation is expected. Given that the mechanisms of insult in these disorders are facilitated by manipulating immune responses, it is factual to assume that the natural sources used for such illnesses may alleviate the immune signals and the subsequent inflammation. In the modern literature, several species of medicinal plants have been shown to have substantial antiinflammatory and immunomodulatory actions, including inhibitory effects on the suppression of cellular and humoral immunity, lymphocyte activation, and propagation of apoptosis. Herein, we review the molecular pharmacology and signaling pathways of inflammation, the chemical components and biological activities of medicinal plants, and their mechanism of action during inflammation at the molecular level. An extensive review of the literature and electronic databases was conducted, encompassing PubMed, Google Scholar, and ScienceDirect to assemble the information.
Fighting against free radicals has become an important strategy in the prevention of oxidative stress-related diseases including cancer. Antioxidants are complex compounds found in vegetables and in our diet that act as a protective shield for our body against such disastrous diseases. In fact, antioxidants are able to interact with free radicals such as hydroxyl, peroxyl, and superoxide groups, preventing them from binding with biological macromolecules (proteins, lipids, and DNA) in healthy human cells. Therefore, lipid peroxidation, oxidative DNA, and protein damage that may result from this interaction will be reduced considerably leading to a significant reduction in genetic events that favor cancer progression. Medicinal plants are known to contain diverse secondary metabolites that are used in the prevention and treatment of diseases or in the promotion of well-being. For this reason, they are potential sources of free radical scavengers, warranting their investigation as antiradical and anticancer agents.
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.