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Exotoxins and endotoxins: Inducers of inflammatory cytokines
Abstract
Endotoxins and exotoxins are among the most potent bacterial inducers of cytokines. During infectious processes, the production of inflammatory cytokines including tumor necrosis factor (TNF), interleukin-1β (IL-1β), gamma interferon (IFNγ) and chemokines orchestrates the anti-infectious innate immune response. However, an overzealous production, leading up to a cytokine storm, can be deleterious and contributes to mortality consecutive to sepsis or toxic shock syndrome. Endotoxins of Gram-negative bacteria (lipopolysaccharide, LPS) are particularly inflammatory because they generate auto-amplificatory loops after activation of monocytes/macrophages. LPS and numerous pore-forming exotoxins also activate the inflammasome, the molecular platform that allows the release of mature IL-1β and IL-18. Among exotoxins, some behave as superantigens, and as such activate the release of cytokines by T-lymphocytes. In most cases, pre-exposure to exotoxins enhances the cytokine production induced by LPS and its lethality, whereas pre-exposure to endotoxin usually results in tolerance. In this review we recall the various steps, which, from the very early discovery of pyrogenicity induced by bacterial products, ended to the discovery of the endogenous pyrogen. Furthermore, we compare the specific characteristics of endotoxins and exotoxins in their capacity to induce inflammatory cytokines.
... Bacterial toxins rank among the most potent modulators of cellular processes in biology (1,2). In particular, proteins secreted by bacteria, known as exotoxins, frequently serve as primary virulence factors during infections. ...
... In particular, proteins secreted by bacteria, known as exotoxins, frequently serve as primary virulence factors during infections. They can function at the bacterial colonization site or migrate to distant organs, eliciting a spectrum of pathophysiological responses that result in the predominant symptoms observed in human infection (1)(2)(3)(4). Studying how these potent disease-causing toxins interact with host cells provides profound insights for developing effective strategies to combat infections and deepen our fundamental understanding of mammalian cellular pathways in host-pathogen interaction. ...
Multifunctional Autoprocessing Repeats-in-Toxin (MARTX) toxins are a diverse effector delivery platform of many Gram-negative bacteria that infect mammals, insects, and aquatic animal hosts. The mechanisms by which these toxins recognize host cell receptors for translocation of toxic effectors into the cell have remained elusive. Here, we map the first surface receptor-binding domain of a MARTX toxin from the highly lethal foodborne pathogen Vibrio vulnificus . This domain corresponds to a 273-amino acid sequence with predicted symmetrical immunoglobulin-like folds. We demonstrate that this domain binds internal N -acetylglucosamine on complex biantennary N-glycans with select preference for L1CAM and other N-glycoproteins with multiple N-glycans on host cell surfaces. This receptor binding domain is essential for V. vulnificus pathogenesis during intestinal infection. The identification of a highly conserved motif universally present as part of all N-glycans correlates with the V. vulnificus MARTX toxin boasting broad specificity and targeting nearly all cell types.
... Stresses also cause gut inflammation-mediated gut dysbiosis including bacterial lipopolysaccharide (LPS) overproduction [6,7]. Overproduced LPS causes tolllike receptor 4-involved NF-κB-mediated inflammation including neuroinflammation [8][9][10][11][12]. Neuroinflammation suppresses the release of serotonin, brain-derived neurotrophic factor (BDNF), and γ-aminobutyric acid (GABA) in the brain, resulting to psychiatric disorder [13][14][15][16]. ...
... The DA-like behavior tasks were conducted in a room equipped with a recording camera and analyzed using EthoVision XT software, as previously reported [8][9][10][11][12]. The OFT was conducted in a chamber measuring 40 × 40 cm, with a defined center zone of 20 × 20 cm. ...
Background
Gut microbiota dysbiosis is closely associated with psychiatric disorders such as depression and anxiety (DA). In our preliminary study, fecal microbiota transplantation from volunteers with psychological stress and subclinical symptoms of depression (Vsd) induced DA-like behaviors in mice. Escherichia fergusonii (Esf) was found to be more abundant in the feces of Vsd compared to healthy volunteers. Therefore, we investigated the effect of Esf on DA-like behavior and neuroinflammation in mice with and without celiac vagotomy.
Methods and results
Orally gavaged Esf increased DA-like behaviors, tumor necrosis factor (TNF)-α, and toll-like receptor-4 (TLR4) expression, and NF-κB⁺Iba1⁺ and lipopolysaccharide (LPS)⁺Iba1⁺ cell populations, while decreasing serotonin, 5-HT1A receptor, and brain-derived neurotrophic factor (BDNF) expression in the hippocampus and prefrontal cortex. However, celiac vagotomy attenuated Esf-induced DA-like behavior and neuroinflammation. Orally gavaged extracellular vesicle (EV) from Vsd feces (vfEV) or Esf culture (esEV) induced DA-like behavior and inflammation in hippocampus, prefrontal cortex and colon. However, celiac vagotomy attenuated vfEV- or esEV-induced DA-like behaviors and inflammation in the brain alone, while vfEV- or esEV-induced blood LPS and TNF-α levels, colonic TNF-α expression and NF-κB-positive cell number, and fecal LPS level were not. Although orally gavaged fluorescence isothiocyanate-labeled esEV was translocated into the blood and hippocampus, celiac vagotomy decreased its translocation into the hippocampus alone.
Conclusions
esEVs may be translocated into the brain via the vagus nerve and bloodstream, subsequently inducing TNF-α expression and suppressing serotonin, its receptor, and BDNF expression through the activation of TLR4-mediated NF-κB signaling, thereby contributing to DA pathogenesis.
... Many species of bacteria produce toxins and other metabolites that inhibit the migration of the skin epithelium and digest the tissue proteins and polysaccharides present in the dermis. Bacterial endotoxins cause elevation of pro-inflammatory cytokines, including IL-1β and TNF-α [11]. Bacterial exotoxins can attack many cell types and cause tissue necrosis [12]. ...
... [140]. In the control group, toxins produced by bacteria elevate pro-inflammatory cytokines (IL-1β, TNF-α) and increase the inflammatory response in wounds [11]. Bacterial metabolites can also cause leukocyte dysfunction [9], which inhibits migration of epidermal cells and keratinocytes [10]. ...
Wound infections may disrupt the normal wound-healing process. Large amounts of antibiotics are frequently used to prevent pathogenic infections; however, this can lead to resistance development. Biomaterials possessing antimicrobial properties have promising applications for reducing antibiotic usage and promoting wound healing. Silk sericin (SS) has been increasingly explored for skin wound healing applications owing to its excellent biocompatibility and antioxidant, antimicrobial, and ultraviolet-resistant properties. In recent years, SS-based composite biomaterials with a broader antimicrobial spectrum have been extensively investigated and demonstrated favorable efficacy in promoting wound healing. This review summarizes various antimicrobial agents, including metal nanoparticles, natural extracts, and antibiotics, that have been incorporated into SS composites for wound healing and elucidates their mechanisms of action. It has been revealed that SS-based biomaterials can achieve sustained antimicrobial activity by slow-release-loaded antimicrobial agents. The antimicrobial-loaded SS composites may promote wound healing through anti-infection, anti-inflammation, hemostasis, angiogenesis, and collagen deposition. The manufacturing methods, benefits, and limitations of antimicrobial-loaded SS materials are briefly discussed. This review aims to enhance the understanding of new advances and directions in SS-based antimicrobial composites and guide future biomedical research.
... Exotoxins and endotoxins can be secreted by bacteria and induce inflammation [109]. For endotoxins, they are released during growth and division and after the death and lysis of the bacteria [110]. ...
... Then the endotoxins activate the immune cells. And excessive activated immune cells would trigger an excessive inflammatory response, called an 'inflammatory storm' [74,109], causing tissue injury, sepsis, amputations, and death [10]. Therefore, eliminating endotoxins is vital for suppressing inflammation. ...
Infectious diseases caused by bacterial infections are common in clinical practice. Cell membrane coating nanotechnology represents a pioneering approach for the delivery of therapeutic agents without being cleared by the immune system in the meantime. And the mechanism of infection treatment should be divided into two parts: suppression of pathogenic bacteria and suppression of excessive immune response. The membrane-coated nanoparticles exert anti-bacterial function by neutralizing exotoxins and endotoxins, and some other bacterial proteins. Inflammation, the second procedure of bacterial infection, can also be suppressed through targeting the inflamed site, neutralization of toxins, and the suppression of pro-inflammatory cytokines. And platelet membrane can affect the complement process to suppress inflammation. Membrane-coated nanoparticles treat bacterial infections through the combined action of membranes and nanoparticles, and diagnose by imaging, forming a theranostic system. Several strategies have been discovered to enhance the anti-bacterial/anti-inflammatory capability, such as synthesizing the material through electroporation, pretreating with the corresponding pathogen, membrane hybridization, or incorporating with genetic modification, lipid insertion, and click chemistry. Here we aim to provide a comprehensive overview of the current knowledge regarding the application of membrane-coated nanoparticles in preventing bacterial infections as well as addressing existing uncertainties and misconceptions.
... In this experiment, W. coagulans BC99 showed a certain inhibitory effect on H. pylori colonization by silver nitrate staining and a recovery effect on gastric and duodenum tissues by HE staining. ET is a kind of lipopolysaccharide, a constituent of the cellular membrane of Gram-negative bacteria, which is released into the blood after bacterial death and causes inflammation in the body (Cavaillon, 2018). Studies have indicated that gastric H. pylori infection may result in the release of chemokines by epithelial and other cells, which in turn attract and activate inflammatory cells, leading to the production of Th1-type cytokines such as IFN-γ and contributing to gastric inflammation (Du et al., 2024;Slomiany & Slomiany, 2017). ...
Helicobacter pylori is a highly prevalent pathogen in human gastric mucosa epithelial cells with strong colonization ability. Weizmannia coagulans is a kind of active microorganism that is beneficial to the improvement of host gut microbiota balance and can prevent and treat intestinal diseases. We investigated the beneficial effects of W. coagulans BC99 in H. pylori infected mice and measured inflammation response, oxidative stress, and gut microbiota. Results showed that BC99 could alleviate the gastric inflammation, inhibit the increasing of inflammation parameters endotoxin, interleukin‐10, transforming growth factor‐β, and interferon‐γ and oxidative stress myeloperoxidase and malondialdehyde, promote the levels of superoxide dismutase and catalase. Furthermore, 16S rRNA gene sequencing analysis revealed that BC99 reversed the change of gut microbiota by reducing the abundance of Olsenella, Candidatus_Saccharimonas, Monoglobus, and increasing the abundance of Tyzzerella. Meanwhile, BC99 caused elevated levels of Ligilactobacillus and Lactobacillus. In view of the beneficial effect of BC99 on the content of short‐chain fatty acid, valeric acid with sodium valerate interfered with H. pylori infection in mice found that valeric acid had a good restorative effect of H. pylori infection relating inflammation and oxidative stress responses. These results suggest that W. coagulans BC99 can be used as a potential probiotic to prevent and treat H. pylori infection by regulating the inflammation, oxidative stress, and gut microbiota.
... Also, the intraperitoneal injection of LPS, which has been shown to be better than other routes, induces peritoneal inflammation that leads to DLB within 24 h via activation of the brainstem, hypothalamus, and the limbic structures via the vagal afferents (Yin et al., 2023). In vivo studies have shown that LPS (when administered either centrally or peripherally) acts as a pathogen-associated molecular pattern (PAMP) that induces peripheral inflammation by activating monocytes, macrophages, endothelial cells, and epithelial cells, which then stimulate the cellular signaling systems to increase various cytokines and pro-inflammatory mediators (Cavaillon, 2018). These peripheral inflammatory signals have been demonstrated to reach the CNS via the endothelial cells or the blood-brain barrier to induce neuroinflammation (Tan et al., 2021) and consequently, depression (Mariani et al., 2022). ...
Introduction
The therapeutic potential of yeast in the management of depression is unknown. Thus, we evaluated the modulatory effect of nutritional yeast supplementation on antidepressant activity of fluoxetine in mice models of depressive-like behaviors (DLB).
Methods
A total of 112 mice were divided into 16 groups (n = 7 each) for a 3-stage study. Stage I (non-DLB study) had groups Ia (10 mL/kg vehicle), Ib (20 mg/kg fluoxetine), Ic – If (2% yeast diet for all, but Id - If additionally received 5 mg/kg, 10 mg/kg, and 20 mg/kg fluoxetine respectively). Stage II (lipopolysaccharide [LPS] model of DLB) had groups IIa - IIb (10 mL/kg vehicle), IIc (20 mg/kg fluoxetine), IId (yeast) and IIe (yeast + 20 mg/kg fluoxetine). After these treatments for 24 days, animals in IIb - IIe received 0.83 mg/kg of LPS on the 25th day. Except for group IIIa (10 mL/kg vehicle), animals in other groups of stage III (unpredictable chronic mild stress [UCMS] model) were exposed to UCMS for 24 days along with 10 mL/kg vehicle (IIIb), 20 mg/kg fluoxetine (IIIc), yeast (IIId), or yeast + fluoxetine (IIIe).
Results
Yeast and fluoxetine attenuated LPS- and UCMS-induced immobility, derangement of oxido-inflammatory (TNF-α, IL-6, NO, MDA, SOD, GSH, CAT, and AChE) and CREB/MAPK pathways. While fluoxetine had more potent effect than yeast when used separately, pre-treatment of mice with their combination had more pronounced effect than either of them.
Conclusion
Yeast supplementation improves the antidepressant activity of fluoxetine in mice by modulating oxido-inflammatory, CREB, and MAPK pathways.
... LPS, an integral constituent of Gram-negative bacterial cell walls, holds the key to activating the innate immune response for radioprotection (Simpson and Trent 2019). Despite exhibiting anti-radiation properties, LPS can also induce severe systemic toxicity (Cavaillon 2018). Our earlier study hinted at a promising candidate-the leukocyte chemotactic peptide fMLP, an analog of LPS-which elicits comparable inflammatory reactions, thus hinting at its potential radioprotective role (Yang et al. 2008). ...
Background
Ionizing radiation (IR), including radiotherapy, can exert lasting harm on living organisms. While liposaccharide (LPS) offers resistance to radiation damage, it also induces toxic responses. Thankfully, an LPS analogue called N-formylmethionine-leucyl-phenylalanine (fMLP) holds the potential to mitigate this toxicity, offering hope for radiation protection.
Methods
Survival of C57BL/6 mice exposed to IR after administration with fMLP/LPS/WR-2721 or saline was recorded. Cell viability and apoptosis assay of bone marrow (BMC), spleen and small intestinal epithelial (HIECs) cells were tested by Cell Counting Kit-8 (CCK-8) and flow cytometry assay. Tissue damage was evaluated by Hematoxilin and Eosin (H&E), Ki-67, and TUNEL staining. RNA sequencing was performed to reveal potential mechanisms of fMLP-mediated radiation protection. Flow cytometry and western blot were performed to verify the radiation protection mechanism of fMLP on the cell cycle.
Results
The survival rates of C57BL/6 mice exposed to ionizing radiation after administering fMLP increased. fMLP demonstrated low toxicity in vitro and in vivo, maintaining cell viability and mitigating radiation-induced apoptosis. Moreover, it protected against tissue damage in the hematopoietic and intestinal system. RNA sequencing shed light on fMLP’s potential mechanism, suggesting its role in modulating innate immunity and cell cycling. This was evidenced by its ability to reverse radiation-induced G2/M phase arrests in HIECs.
Conclusion
fMLP serves as a promising radioprotective agent, preserving cells and radiosensitive tissues from IR. Through its influence on the cell cycle, particularly reversing radiation-induced arrest in G2/M phases, fMLP offers protection against IR’s detrimental effects.
... Endotoxins originate from the outer membrane of Gram-negative bacteria. They are composed of lipopolysaccharide (LPS), consisting of an acylated backbone (lipid A) responsible for the induction of a proinflammatory immune response, a chain of repeated sugar units (O-antigen) and an oligosaccharide core (O'Neill et al., 2013;Cavaillon, 2018;Sondhi et al., 2024). If present, LPS contaminants can interact with LPS-binding protein (LBP), Myeloid differentiation protein 2 (MDA2), CD14 and Toll-Like Receptor 4 (TLR4), thereby leading to signal transduction through the TRIF and MyD88 pathways, resulting in the secretion of proinflammatory cytokines such as IL-6, TNF-α, and IL-1 (O'Neill et al., Sondhi et al., 2024). ...
The success of messenger (m)RNA-based vaccines against SARS-CoV-2 during the COVID-19 pandemic has led to rapid growth and innovation in the field of mRNA-based therapeutics. However, mRNA production, whether in small amounts for research or large-scale GMP-grade for biopharmaceutics, is still based on the In Vitro Transcription (IVT) reaction developed in the early 1980s. The IVT reaction exploits phage RNA polymerase to catalyze the formation of an engineered mRNA that depends on a linearized DNA template, nucleotide building blocks, as well as pH, temperature, and reaction time. But depending on the IVT conditions and subsequent purification steps, diverse byproducts such as dsRNA, abortive RNAs and RNA:DNA hybrids might form. Unwanted byproducts, if not removed, could be formulated together with the full-length mRNA and cause an immune response in cells by activating host pattern recognition receptors. In this review, we summarize the potential types of IVT byproducts, their known biological activity, and how they can impact the efficacy and safety of mRNA therapeutics. In addition, we briefly overview non-nucleotide-based contaminants such as RNases, endotoxin and metal ions that, when present in the IVT reaction, can also influence the activity of mRNA-based drugs. We further discuss current approaches aimed at adjusting the IVT reaction conditions or improving mRNA purification to achieve optimal performance for medical applications.
... Under negative energy balance conditions like those elicited by the peripheral administration of LPS, a reduction in food intake is commonly observed, followed by a fall in arc POMC and arc NPY/AgRP neuronal activity [37], in parallel to a decreased circulating thyroid hormone level, and an LPSinduced rise in corticosterone [17,38]. These hormonal signals are key elements to reduce energy expenditure and activate the immune response, triggered by the activation of a Tolllike receptor-4 (TLR4), a CD14 receptor for LPS, and the rise in pro-inflammatory cytokines such as IL-1β, IL-6, and TNF-α, which are essential for the induction of the inflammatory response [39][40][41][42][43]. Fasting increases the expression of the neuronal activity marker c-fos in NPY neurons [44,45] and reduces food intake due to LPS illness, increasing the number of cells expressing c-fos+, CD14+, or c-fos+/CD14+ mRNA, in a sub-population of the arcuate no larger than 20%, reminiscent of the total number of NPY cells in the arcuate [15]. ...
Abstract: Pereskia sacharosa Griseb. is a plant used in traditional herbal medicine to treat inflammation. We analyzed the phenolic content of P. sacharosa leaves (EEPs) by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and investigated the anti-inflammatory properties of EEPs and its flavonoid fraction (F10) in animal models subjected to acute neuroinflammation induced by bacterial lipopolysaccharide (LPS). Coronal brain sections of C57BL/6JN male mice or Wistar male rats administered with EEPs or F10 before LPS were subjected to in situ hybridization to determine c-fos and CD14 mRNA levels in the hypothalamus or GABA A γ2 mRNA levels in the hippocampus. Theta oscillations were recorded every 6 h in the hippocampus of Wistar rats. In total, five flavonoids and eight phenolic acids were identified and quantified in P. sacharosa leaves. Either EEPs or F10 crossed the blood-brain barrier (BBB) into the brain and reduced the mRNA expression of c-fos, CD14, and GABA A γ2. A decrease in theta oscillation was observed in the hippocampus of the LPS group, while the F10 + LPS group overrode the LPS effect on theta activity. We conclude that the bioactive compounds of P. sacharosa reduce the central response to inflammation, allowing the early return of ambulatory activity and well-being of the animal.
... Sepsis is one of the most common clinical diseases in the emergency department and ICU, which is characterized by the high expression of various inflammatory mediators and cytokines caused by the invasion of pathogenic microorganisms into the human body [1][2][3]. Epidemiologic studies and clinical investigations have shown that lipopolysaccharide (LPS), the main component of cell wall of Gram-negative bacteria, is an important cause of sepsis induced by bacterial infection [4,5]. Many medical documents showed that LPS can induce the synthesis Page 2 of 10 Wang et al. ...
Background
Sepsis is one of the most common clinical diseases, which is characterized by a serious and uncontrollable inflammatory response. LPS-induced inflammation is a critical pathological event in sepsis, but the underlying mechanism has not yet been fully elucidated.
Methods
The animal model was established for two batches. In the first batch of experiments, Adult C57BL/6J mice were randomly divided into control group and LPS (5 mg/kg, i.p.)group . In the second batch of experiments, mice were randomly divided into control group, LPS group, and LPS+VX765(10 mg/kg, i.p., an inhibitor of NLRP3 inflammasome) group. After 24 hours, mice were anesthetized with isoflurane, blood and intestinal tissue were collected for tissue immunohistochemistry, Western blot analysis and ELISA assays.
Results
The C57BL/6J mice injected with LPS for twenty-four hours could exhibit severe inflammatory reaction including an increased IL-1β, IL-18 in serum and activation of NLRP3 inflammasome in intestine. The injection of VX765 could reverse these effects induced by LPS. These results indicated that the increased level of IL-1β and IL-18 in serum induced by LPS is related to the increased intestinal permeability and activation of NLRP3 inflammasome. In the second batch of experiments, results of western blot and immunohistochemistry showed that Slit2 and Robo4 were significant decreased in intestine of LPS group, while the expression of VEGF was significant increased. Meanwhile, the protein level of tight junction protein ZO-1, occludin, and claudin-5 were significantly lower than in control group, which could also be reversed by VX765 injection.
Conclusions
In this study, we revealed that Slit2-Robo4 signaling pathway and tight junction in intestine may be involved in LPS-induced inflammation in mice, which may account for the molecular mechanism of sepsis.
... In human whole blood samples, ExoA was demonstrated to specifically bind to the alpha2-macroglobulin receptor, which interaction induces a specific, dose-dependent, and tumor necrosis factor (TNF)-independent repression of antimicrobial cytokine production and monocyte activating factor CD14 [72]. As the current knowledge shows, there is no mammalian ortholog of ZIP-2; instead, exotoxin A is an essential inducer of cytokine storms in macrophages and T cells [102]. ...
Infections, such as that by the multiresistant opportunistic bacterial pathogen Pseudomonas aeruginosa, may pose a serious health risk, especially on vulnerable patient populations. The nematode Caenorhabditis elegans provides a simple organismal model to investigate both pathogenic mechanisms and the emerging role of innate immunity in host protection. Here, we review the virulence and infection strategies of P. aeruginosa and host defenses of C. elegans. We summarize the recognition mechanisms of patterns of pathogenesis, including novel pathogen-associated molecular patterns and surveillance immunity of translation, mitochondria, and lysosome-related organelles. We also review the regulation of antimicrobial and behavioral defenses by the worm’s neuroendocrine system. We focus on how discoveries in this rich field align with well-characterized evolutionary conserved protective pathways, as well as on potential crossovers to human pathogenesis and innate immune responses.
... For example, increased exposure to fungal cell wall material, βd-glucan (BDG), is negatively associated with FEV 1 and increases the risk of emergency/urgent care visits in asthmatics by nearly nine-fold in children (Blatter et al., 2014). Exposure to indoor bacterial endotoxin and mold BDG are known respiratory irritants and potent cytokine inducers (Cavaillon, 2018;Douwes et al., 2000;Kizhakke Puliyakote et al., 2023). ...
Pro‐inflammatory fungal β‐d‐glucan (BDG) polysaccharides cause respiratory pathology. However, specific immunological effects of unique BDG structures on pulmonary inflammation are understudied. We characterized the effect of four unique fungal BDGs with unique branching patterns, solubility, and molecular weights in murine airways. Scleroglucan (1 → 3)(1 → 6)‐highly branched BDG, laminarin (1 → 3)(1 → 6)‐branched BDG, curdlan (1 → 3)‐linear BDG, and pustulan (1 → 6)‐linear BDG were assessed by nuclear magnetic resonance spectroscopy. Each BDG was tested by inhalation model with C3HeB/FeJ mice and compared to saline‐exposed control mice and unexposed sentinels (n = 3–19). Studies were performed ±heat‐inactivation (1 h autoclave) to increase BDG solubility. Outcomes included bronchoalveolar lavage (BAL) differential cell counts (macrophages, neutrophils, lymphocytes, eosinophils), cytokines, serum IgE, and IgG2a (multiplex and ELISA). Ex vivo primary cells removed from lungs and plated at monolayer were stimulated (BDG, lipopolysaccharide (LPS), anti‐CD3), and cytokines compared to unstimulated cells. Right lung histology was performed. Inhalation of BDGs with distinct branching patterns exhibited varying inflammatory potency and immunogenicity. Lichen‐derived (1 → 6)‐linear pustulan was the most pro‐inflammatory BDG, increasing inflammatory infiltrate (BAL), serum IgE and IgG2a, and cytokine production. Primed lung cells responded to secondary LPS stimulation with a T‐cell‐specific response to pustulan. Glucan source and solubility should be considered in exposure and toxicological studies.
... This correlation is affirmed in our study, where the patients without wound complications were an average age of 60.8, while those with wound healing disorders were significantly older (67.8). The presence of previous illnesses or comorbidities has been linked to an increased rate of postoperative complications by various authors, and our data confirm this correlation [48,49]. The ASA score has been associated with postoperative wound infections in some studies [50,51]. ...
Postoperative wound infections are a prevalent concern among the hospital-associated infections in Europe, leading to prolonged hospital stays, increased morbidity and mortality, and substantial patient burdens. Addressing the root causes of this complication is crucial, especially given the rising number of spine surgeries due to aging populations. Methods: A retrospective analysis was conducted on a cohort of 3019 patients who underwent lumbar spine surgery over a decade in our department. The study aimed to assess the predictors of wound healing disorders, focusing on laboratory values, particularly inflammatory parameters. Results: Of the 3019 patients, 2.5% (N = 74) experienced deep or superficial wound healing disorders, showing the significant correlation between C-reactive protein (CRP) levels and these disorders (p = 0.004). A multivariate analysis identified several factors, including age, sex, hypertension, diabetes, cardiac comorbidity, surgical duration, dural injury, and blood loss, as being correlated with wound healing disorders. Conclusion: Demographic factors, pre-existing conditions, and perioperative variables play a role in the occurrence of adverse effects related to wound healing disorders. Elevated CRP levels serve as an indicator of increased infection risk, though they are not a definitive diagnostic tool for wound healing disorders.
... 6-10 Cytokines can enhance host defense against viruses and meanwhile induce the reorganization of endothelial cytoskeletons and junctions, causing an increase in endothelial permeability. [13][14][15] Increased endothelial permeability leads to dysfunction of the vascular endothelial barrier, manifesting cutaneous petechiae, edema, [15][16][17][18] In this study, we found that in the early stage of HFRS, all enrolled patients exhibited varying degrees of neutrophil elevation and excessive expression of inflammatory factors. The sivelestat group had significantly lower cytokine levels at various time points, compared to the control group. ...
Background
In Asia, Hanta virus (HTNV) results in severe hemorrhagic fever with renal syndrome (HFRS). The efficacy of sivelestat in treating children with HTNV-induced HFRS remains unclear.
Methods
An ambispective cohort study was performed on children diagnosed with HFRS and hospitalized at the Children’s Hospital Affiliated to Xi’an Jiaotong University from August 2018 to 2023. Patients who received neutrophil elastin-inhibitor infusion between August 2019 and August 2023 were assigned to the sivelestat group, while patients who did not were assigned to the control group. The independent sample t test was used for inter-group analysis. The Chi-square test and Fisher’s exact probability test were used for categorical variables. Spearman correlation test was used to evaluate the correlation between two sets of continuous variables. Kaplan-Meier survival curve and Log -Rank test was used to evaluate the difference in cumulative probability of survival between the two groups.
Results
No significant differences were observed between the two groups in gender, age, contact history, body mass index, HFRS severity, clinical indexes at admission. Compared to the control group, the sivelestat group exhibited a significant decrease in the interleukin-8 level at 48 h (28.5±3 vs 34.5±3.5) and 72 h (21.3±4.5 vs 31.5±5.6) (P<0.05), as well as the ICAM-1 level at 48 h (553±122 vs 784±187) and 72 h (452±130 vs 623±85) (P<0.05). The concentration of VCAM-1 in the sivelestat group exhibited a consistent downward trend. Moreover, the level of VCAM-1 was significantly lower than that in the control group at 24 h (1760±289 vs 2180±445), 48 h (1450±441 vs 1890±267), and 72 h (1149±338 vs 1500±396) (P<0.05). Kaplan-Meier curve analysis revealed a statistically significant difference in the cumulative probability of survival between two groups (P = 0.041). In the secondary outcomes, the sivelestat group demonstrated a decrease in the utilization rate of mechanical ventilation and continuous renal replacement therapy (CRRT).
Conclusion
Sivelestat may suppress neutrophil-mediated inflammatory response to reduce endothelial and organ damage, and improve clinical outcomes in children with severe hemorrhagic fever and renal syndrome.
... In the present study, we found that only aripiprazole inhibited the LPS-induced production of IL-6 and IL-10 in MIA OCCs. This endotoxin is one of the most potent bacterial inducers of cytokine release, including not only proinflammatory (TNF-α, IL-1β and IL-6) but also anti-inflammatory factors such as IL-10 [103][104][105]. LPS triggers the induction of IL-10 secretion, efficiently preventing the expression of proinflammatory factors [106]. ...
Microglia are the primary innate immune cells of the central nervous system and extensively contribute to brain homeostasis. Dysfunctional or excessive activity of microglia may be associated with several neuropsychiatric disorders, including schizophrenia. Therefore, we examined whether aripiprazole and risperidone could influence the expression of the Cd200–Cd200r and Cx3cl1–Cx3cr1 axes, which are crucial for the regulation of microglial activity and interactions of these cells with neurons. Additionally, we evaluated the impact of these drugs on microglial pro- and anti-inflammatory markers (Cd40, Il-1β, Il-6, Cebpb, Cd206, Arg1, Il-10 and Tgf-β) and cytokine release (IL-6, IL-10). The research was executed in organotypic cortical cultures (OCCs) prepared from the offspring of control rats (control OCCs) or those exposed to maternal immune activation (MIA OCCs), which allows for the exploration of schizophrenia-like disturbances in animals. All experiments were performed under basal conditions and after additional stimulation with lipopolysaccharide (LPS), following the “two-hit” hypothesis of schizophrenia. We found that MIA diminished the mRNA level of Cd200r and affected the OCCs’ response to additional LPS exposure in terms of this parameter. LPS downregulated the Cx3cr1 expression and profoundly changed the mRNA levels of pro- and anti-inflammatory microglial markers in both types of OCCs. Risperidone increased Cd200 expression in MIA OCCs, while aripiprazole treatment elevated the gene levels of the Cx3cl1–Cx3cr1 dyad in control OCCs. The antipsychotics limited the LPS-generated increase in the expression of proinflammatory factors (Il-1β and Il-6) and enhanced the mRNA levels of anti-inflammatory components (Cd206 and Tgf-β) of microglial polarization, mostly in the absence of the MIA procedure. Finally, we observed a more pronounced modulating impact of aripiprazole on the expression of pro- and anti-inflammatory cytokines when compared to risperidone in MIA OCCs. In conclusion, our data suggest that MIA might influence microglial activation and crosstalk of microglial cells with neurons, whereas aripiprazole and risperidone could beneficially affect these changes in OCCs.
... This effect was abrogated in absence of IFN-γ and when endolysin was added to the bacterial culture. Staphylococcal enterotoxins (SE) belong to a group of bacterial toxins -the exotoxins -that are produced and secreted by live bacteria only, which contrasts with other types of bacterial toxins that are an integral part of the bacterial wall and found in debris from dead bacteria (Cavaillon, 2018). As endolysin inhibits the production and release of SE by killing of patient-derived S. aureus , our findings suggest that only live, SE-producing S. aureus -via presentation HLA-class II positive keratinocytes -can stimulate release of malignant T cell growth factors and proliferation of malignant-and non-malignant T cells, whereas bacterial debris from S. aureus cannot. ...
... Cytokines have various functions, including immunomodulation, cell growth, and tissue repair (15). Cytokines can be categorized into interleukins, chemokines, and growth factors (16). The exact etiology and pathogenesis of KOA remain unclear. ...
Objectives
Knee osteoarthritis (KOA) and certain inflammatory cytokines (such as interleukin 1 [IL-1] and tumor necrosis factor alpha [TNF-a]) are related; however, the causal relationship remains unclear. Here, we aimed to assess the causal relationship between 41 inflammatory cytokines and KOA using Mendelian randomization (MR).
Methods
Two-sample bidirectional MR was performed using genetic variation data for 41 inflammatory cytokines that were obtained from European Genome-Wide Association Study (GWAS) data (n=8293). KOA-related genetic association data were also obtained from European GWAS data (n=40,3124). Inverse variance weighting (IVW), MR, heterogeneity, sensitivity, and multiple validation analyses were performed.
Results
Granulocyte colony-stimulating factor (G-CSF) or colony-stimulating factor 3 (CSF-3) levels were negatively associated with the risk of developing KOA (OR: 0.93, 95%CI:0.89–0.99, P=0.015). Additionally, macrophage inflammatory protein-1 alpha (MIP-1A/CCL3) was a consequence of KOA (OR: 0.72, 95%CI:0.54–0.97, P=0.032). No causal relationship was evident between other inflammatory cytokines and KOA development.
Conclusion
This study suggests that certain inflammatory cytokines may be associated with KOA etiology. G-CSF exerts an upstream influence on KOA development, whereas MIP-1A (CCL-3) acts as a downstream factor.
... The heightened secretion of endotoxin, a bacterial product, induced by an imbalance in the gut microbiota among patients with cirrhosis, results in liver damage (69). Endotoxin can exacerbate liver damage by amplifying the release of inflammatory factors (70). Therefore, regulating the gut microbial profile is crucial for preventing cirrhosis progression. ...
Introduction
Gut dysbiosis may play a pivotal role in the pathogenesis of cirrhosis and the severity of complications. Numerous studies have investigated the probiotics as treatments for cirrhosis. However, there is still a lack of definitive evidence confirming the beneficial effects of probiotics on cirrhosis.
Methods
Databases including PubMed, Embase, Web of Science, and the Cochrane Library were systematically searched for randomized controlled trials that compared the effects of probiotic intervention and control treatments, including placebo, no treatment, and active control, on cirrhosis, published from inception to February 2024. Outcomes included hepatic encephalopathy (HE) reversal, safety and tolerability of probiotics, liver function, quality of life, and other cirrhotic-related outcomes. A meta-analysis was conducted to synthesize evidence.
Results
Thirty studies were included. The quantitative synthesis results showed that compared with the control group, probiotics significantly reverse minimal hepatic encephalopathy (MHE) (risk ratio [RR] 1.54, 95% confidence interval [CI] 1.03 to 2.32) and improve HE (RR 1.94, 95% CI 1.24 to 3.06). Additionally, probiotics demonstrated higher safety and tolerability by causing a lower incidence of serious adverse events (RR 0.71, 95% CI 0.58 to 0.87). Probiotics could potentially improve liver function by reducing the Model for End-Stage Liver Disease (MELD) scores (standardized mean difference [SMD] -0.57, 95% CI -0.85 to −0.30), and displayed favorable changes in quality of life (SMD 0.51, 95% CI 0.27 to 0.75) and gut flora (SMD 1.67, 95% CI 1.28 to 2.06).
Conclusion
This systematic review and meta-analysis offers compelling evidence that probiotics are beneficial for cirrhosis by demonstrating reversal of HE, potential for liver function improvements, enhancements in quality of life, and regulation of gut dysbiosis. Furthermore, the apparent safety profile suggests that probiotics are a promising intervention for treating cirrhosis.
Clinical trial registration number
CRD42023478380.
... It is known from the analyzed scientific sources that the basis of IFA is test-systems, with the help of which, if the reaction is carried out correctly, it is possible to obtain true results and make reasonable conclusions. To date, test systems for the detection of endotoxins of gramnegative bacteria have not been developed among known pathogens, so it is not possible to detect them using the IFA method [1,8,14]. ...
The purpose of the study was to determine the specificity and sensitivity of the immunoenzymatic test system that detects antibodies against the antigens of these bacteria in order to evaluate antiendotoxic immunity against GShPB endotoxins. It was found that flat bottom polystyrene solid phase carrier was selected for the proposed experimental test system for the detection of endotoxins of these bacteria by IFA method. The sensitivity of the recommended test system was 75% in colon dysbiosis, 76% in acute tonsillitis, 89% in acute bronchitis, and 95% in urinary tract infections, and the specificity was 5-25%, thus the diagnostic value of this test system it was proved for the first time.
... The severe inflammatory response caused by sepsis is responsible for the high mortality rate [28]. The pathophysiology of sepsis is characterized by hyperactive and dysregulated endogenous inflammatory mediators, including IL-1β, IL-18, and TNF-α [29,30]. Sepsis can lead to inflammatory damage in nearly every organ system [31]. ...
Cardiomyocyte pyroptosis is a primary contributor to sepsis-induced cardiac dysfunction (SICD). Recombinant phospholipid transfer protein (PLTP) have been demonstrated to possess anti-inflammatory and antiseptic properties. However, the effect of PLTP on SICD remains unknown. In this study, we established the in vivo and in vitro sepsis model with the recombinant PLTP treatment. The survival rates of mice, mouse cardiac function, cell viability, the protein level of proinflammatory cytokine, and lactate dehydrogenase level were evaluated. The cardiomyocyte pyroptotic changes were observed. The distribution of PLTP and NOD-like receptor thermal protein domain associated protein 3 (NLRP3) in mouse myocardial tissue and expression of PLTP, apoptosis associated speck like protein containing a CARD (ASC), NLRP3, caspase-1, interleukin (IL)-1β, and Gasdermin D (GSDMD) were detected. PLTP ameliorated the cecal ligation and puncture-induced mouse survival rate decrease and cardiac dysfunction, inhibited the IL-1β, IL-18, and tumor necrosis factor (TNF)-α release, and blocked the NLRP3 inflammasome/GSDMD signaling pathway in septic mice. In vitro, PLTP reversed the lipopolysaccharide-induced cardiomyocyte pyroptosis, expression of IL-1β, IL-6, TNF-α, and activation of the NLRP3 inflammasome/GSDMD signal pathway. Moreover, PLTP could bind to NLRP3 and negatively regulate the activity of the NLRP3 inflammasome/GSDMD signal pathway. This study demonstrated that PLTP can ameliorate SICD by inhibiting inflammatory responses and cardiomyocyte pyroptosis by blocking the activation of the NLRP3 inflammasome/GSDMD signaling pathway.
... One study shows that lipopolysaccharides (LPS) trigger immune stresscan incite immune stress by stimulating host immune cells to produce nitric oxide (NO) and cytokines, including tumor necrosis factor-alpha (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6) [50]. Due to their capability to release NO, activated RAW264.7 cells are frequently used to evaluate the immunomodulatory activity of compounds [27]. ...
Polysaccharides extracted from Taxus media hrough an aqueous method were further refined by removing proteins via the Sevag technique and purified by dialysis. The separation of these polysaccharides was accomplished using a DEAE-cellulose chromatog-raphy column, yielding two distinct fractions, named CPTM-P1 and CPTM-P2. Notably, CPTM-P1 emerged as the primary polysaccharide component within Taxus media. Consequently, a comprehensive analysis focusing exclusively on CPTM-P1 was undertaken. The molecular weight of CPTM-P1 was established through gel permeation chromatography (GPC), and its monosaccharide composition was deciphered using HPLC-MS. The structure was further elucidated through nuclear magnetic resonance (NMR) spectroscopy. The molecular weight of CPTM-P1 was determined to be 968.7 kDa. The monosaccharide composition consisted of galactose (Gal), arabinose (Ara), galacturonic acid (Gal-UA), glucose (Glc), rhamnose (Rha), xylose (Xyl), mannose (Man), fucose (Fuc), glucuronic acid (Glc-UA), and ribose (Rib). The proportional distribution of these components was 30.53%, 22.00%, 5.63%, 11.67%, 11.93%, 1.69%, 8.50%, 1.23%, 5.63%, and 1.17%, respectively. This confirmed CPTM-P1 as an acidic heteropolysaccharide with a glycuronic acid backbone. Moreover, CPTM-P1 showed immunoenhancing properties, effectively augmenting the secretion of nitric oxide and cytokines (TNF-α, IL-1β, and IL-6). Additionally, it significantly enhances the phagocytic capacity of RAW264.7 cells. These findings underscore the potential application of these polysaccharides in functional foods and pharmaceuticals, providing a solid scientific basis for further exploration and utilization of Taxus media polysaccharides.
... While LPS-induced endotoxemia does not fully reproduce the hemodynamic changes seen in septic humans, 45 this model has several advantages including higher reproducibility and a well-characterized acute inflammatory response. 21,46,47 Young mice showed no change in BT when given the 0.1 mg LPS/kg dose compared to a commonly used dose of 1 mg/kg or a lethal dose of 18 mg/kg ( Figure S2A). We predicted that even at the lowest LPS dose, old mice would exhibit more severe outcomes as measured by hypothermia and cytokine gene expression ( Figure 2A). ...
Non-canonical lipolysis induced by inflammatory cytokines or Toll-like receptor ligands is required for the regulation of inflammation during endotoxemia and sepsis. Canonical lipolysis induced by catecholamines declines during aging due to factors including an expansion of lymphocytes, pro-inflammatory macrophage polarization, and an increase in chronic low-grade inflammation; however, the extent to which the non-canonical pathway of lipolysis is active and impacted by immune cells during aging remains unclear. Therefore, we aimed to define the extent to which immune cells from old mice influence non-canonical lipolysis during sepsis. We identified age-associated impairments of non-canonical lipolysis and an accumulation of dysfunctional B1 B cells in the visceral white adipose tissue (vWAT) of old mice. Lifelong deficiency of B cells results in restored non-canonical lipolysis and reductions in pro-inflammatory macrophage populations. Our study suggests that targeting the B cell-macrophage signaling axis may resolve metabolic dysfunction in aged vWAT and attenuate septic severity in older individuals.
... Additionally, IFN-γ is another essential pro-inflammatory cytokine that is released during various inflammatory conditions [34,35]. Endotoxins and exotoxins are the most common inducers of cytokine production [36]. As inflammation progresses, the generation of inflammatory cytokines, including TNF-α and IFN-γ, orchestrates the innate immune response against infections [37]. ...
Intestinal mucositis (IM) is a common adverse effect of chemotherapy, limiting its clinical application. Codonopsis pilosula-derived CP-A (an inulin-type fructan) is an edible Chinese medicine with anti-inflammatory and gastrointestinal protective effects, which may be useful for treating IM. Here, we explored CP-A’s role in ameliorating IM induced by 5-fluorouracil (5-FU) and investigated the underlying mechanism using in vitro experiments and rat models. Western blotting, immunohistochemistry (IHC), and real-time PCR (RT-PCR) analyses were used to assess protein expression related to the extracellular-regulated protein kinases (ERK)/myosin light chain kinase (MLCK)/myosin light chain 2 (MLC2) signaling pathway and tight junction proteins. Inflammatory factors were quantified using enzyme-linked immunosorbent assays (ELISAs), and 16S rRNA amplicon sequencing was employed for cecum content analysis. The results indicated that CP-A restored body weight and food intake and reversed histopathological changes in IM rats. Further, abnormal MLCK activation induced by 5-FU was attenuated by CP-A via the ERK/MLCK/MLC2 pathway. CP-A treatment improved tight junction protein levels and reduced inflammatory factor expression. Moreover, CP-A intervention regulated the intestinal microbiota community structure, increasing the abundance of Lactobacillus and decreasing the abundance of Shigella. In conclusion, CP-A mitigates 5-FU-induced IM by inhibiting the ERK/MLCK/MLC2 pathway, reducing the expression of inflammatory factors, improving the intestinal mucosal barrier, and regulating the intestinal microbial community. This study highlights CP-A’s therapeutic potential in IM treatment and provides insights for future research.
... This may be advantageous in preventing conditions with an exaggerated inflammatory response, such as the cytokine storm which may be seen in sepsis and is associated with increased mortality. 26 However, there may be a reduction in the innate inflammatory response to infection indicating a relative immunosuppression. 12 The NLRP3 inflammasome is an essential component of the innate immune system. ...
Background
Infections cause significant morbidity and mortality in children with Severe Neurological Impairment (SNI). Alterations in immune cell numbers and function in children with neurodisability have been reported. We aimed to characterise neutrophil, monocyte and lymphocyte proportions and activation, at baseline and in response to stimulation with lipopolysaccharide, in children with SNI compared to healthy controls.
Methods
Whole blood samples of children with SNI and controls were incubated in the presence or absence of lipopolysaccharide (10 ng/ml). Monocyte and neutrophil function (Cluster of Differentiation (CD)11b, (TLR)-4 and CD66b expression) and lymphocytes were assessed by flow cytometry. Expression of genes involved in the inflammasome (NLR Family Pyrin Domain Containing( NLRP)-3 , Apoptosis-Associated Speck-like protein (ASC) and Interleukin( IL)1β ) were assessed by PCR.
Results
Monocytes and CD8+ T cells were lower in children with SNI ( n = 14). CD66b, was hyporesponsive and monocyte TLR4 was hyperresponsive to lipopolysaccharide in children with SNI compared to controls ( n = 14). NLRP3 expression was higher at baseline and IL1β expression was not upregulated in response to lipopolysaccharide in children with SNI in contrast to controls.
Conclusion
We have found significant differences in immune regulation in children with SNI compared to controls which may provide a useful therapeutic target in the future.
Impact
Children with SNI have reduced monocyte and CD8+ T cells.
Neutrophils and monocytes in children with SNI show altered markers of activation in response to lipopolysaccharide.
Expression of NLRP3 at the RNA level was higher at baseline in children with SNI.
This study adds to the existing literature that children with neurological impairment have altered inflammatory and immune cell responses.
This may provide a useful therapeutic target to reduce infection-related morbidity and mortality, and tertiary neurological injury in the future.
... When the endotoxin LPS is released into the body in large quantities because of infection, excessive production of inflammatory cytokines occurs, which leads to systemic intravascular coagulation, lowered blood pressure, and septic shock (fatal endotoxin shock). Septic shock is still a serious systemic disease with a high mortality rate, and if untreated, it progresses to multiple organ failure and death (56,102). Model mice that receive LPS are widely used to understand the pathology of sepsis and to serve as a treatment model. ...
Innate immunity plays an important role in host defense against microbial infections. It also participates in activation of acquired immunity through cytokine production and antigen presentation. Pattern recognition receptors such as Toll-like receptors and nucleotide oligomerization domain-like receptors sense invading pathogens and associated tissue injury, after which inflammatory mediators such as pro-inflammatory cytokines and nitric oxide are induced. Supersulfides are molecular species possessing catenated sulfur atoms such as persulfide and polysulfide moieties. They have recently been recognized as important regulators in cellular redox homeostasis by acting as potent antioxidants and nucleophiles. In addition, recent studies suggested that supersulfides are critically involved in the regulation of innate immune and inflammatory responses. In this review, we summarize current knowledge of the chemistry and biology of supersulfides, with particular attention to their roles in regulation of innate immune and inflammatory responses. Studies with animal models of infection and inflammation demonstrated the potent anti-inflammatory functions of supersulfides such as blocking pro-inflammatory signaling cascades, reducing oxidative stresses, and inhibiting replication of microbial pathogens including severe acute respiratory syndrome coronavirus 2. Precise understanding of how supersulfides regulate innate immune responses is the necessary requirement for developing supersulfide-based diagnostic as well as therapeutic strategies against inflammatory disorders.
... During infectious processes, excessive production of proinflammatory cytokines leads to a cytokine storm, thereby contributing to mortality consecutive to sepsis syndrome [29]. ELISA showed that the LPS-induced levels of TNF-a, IL-6, and IL-1b in the serum of mice that were pretreated with PZH were significantly reduced at 2 h after LPS injection (Fig. 1D). ...
Pien Tze Huang (PZH), a class I nationally protected traditional Chinese medicine (TCM), has been used to treat liver diseases such as hepatitis; however, the effect of PZH on the progression of sepsis is unknown. Here, we reported that PZH attenuated lipopolysaccharide (LPS)-induced sepsis in mice and reduced LPS-induced production of proinflammatory cytokines in macrophages by inhibiting the activation of mitogen-activated protein kinase (MAPK) and nuclear factor-kappa B (NF-κB) signalling. Mechanistically, PZH stimulated signal transducer and activator of transcription 3 (STAT3) phosphorylation to induce the expression of A20, which could inhibit the activation of NF-κB and MAPK signalling. Knockdown of the bile acid (BA) receptor G protein-coupled bile acid receptor 1 (TGR5) in macrophages abolished the effects of PZH on STAT3 phosphorylation and A20 induction, as well as the LPS-induced inflammatory response, suggesting that BAs in PZH may mediate its anti-inflammatory effects by activating TGR5. Consistently, deprivation of BAs in PZH by cholestyramine resin reduced the effects of PZH on the expression of phosphorylated-STAT3 and A20, the activation of NF-κB and MAPK signalling, and the production of proinflammatory cytokines, whereas the addition of BAs to cholestyramine resin-treated PZH partially restored the inhibitory effects on the production of proinflammatory cytokines. Overall, our study identifies BAs as the effective components in PZH that activate TGR5-STAT3-A20 signalling to ameliorate LPS-induced sepsis.
Leptospirosis is a neglected re-emerging zoonosis caused by Leptospira spirochetes. Its pathophysiology remains mysterious, especially in the case of severe infection with L. interrogans.
In the field of infectious diseases, the cause of death is rarely investigated in preclinical models. Here, for the first time, we identified unanticipated organ failures associated with death in a murine model of acute leptospirosis.
Despite clinical similarities between bacterial sepsis and leptospirosis, striking differences were observed. Neither lung, liver, or kidney injury nor cytokine storm, or massive necroptosis could explain death. In contrast, severe leptospirosis was associated with high serum levels of the anti-inflammatory cytokine IL-10 and the chemokine RANTES, neutrophilia, pancreatitis and vascular damage. Unexpectedly, we demonstrated neutrophil-induced vascular permeability, making neutrophils a potential new therapeutic target. Strikingly, the main cause of death was myocarditis, an overlooked complication of human leptospirosis.
These features are also found in patients, making this model a paradigm for better understanding human leptospirosis and designing novel therapeutic strategies.
Background
It has been reported that the imbalance of gut microbiota is involved in the pathogenesis of psoriasis. We retrieved randomized placebo-controlled trials to evaluate the efficacy and safety of probiotic administration in the treatment of psoriasis.
Methods
The outcomes were changes in Psoriasis Area and Severity Index (PASI), Dermatology Life Quality Index (DLQI), and serum inflammatory indicators after treatment, and adverse events (AEs). Risk ratios (RRs) and mean differences (MDs) were calculated using random or fixed effects model.
Results
Seven qualified studies were identified in our study. The pooled percentage of patients with ≥75% reduction from baseline in PASI was higher in the probiotic group than that in the placebo group (33.57% vs. 23.61%; RR 1.40, 95% CI 0.98–1.98, p = 0.06). Compared with the placebo group, the PASI (MD −3.09, 95% CI −5.04 to −0.74, p = 0.01) and CRP level (MD −2.36, 95% CI −2.77 to −1.95, p < 0.0001) were significantly reduced in the probiotic group. There was no significant difference in DLQI (MD −1.45, 95% CI −6.72 to 3.82, p = 0.59) and AEs (RR 0.68, 95% CI 0.37–1.25, p = 0.22) between the two groups.
Conclusion
Oral administration of probiotics can improve psoriasis; however, large randomized controlled trials are needed to support this conclusion.
Systematic review registration
PROSPERO, identifier CRD42024506286, https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42024506286.
Bacterial venoms are venomous elements that are made and released by bacteria to aim on other bacterial or host cells. Bacteria usually have antitoxins to avert the harmful effects of venom. The bacterial venoms either lipopolysaccharides associated with the cell wall of Gram-negative bacteria or proteins released from bacterial cells and may act at tissue sites removed from the site of bacterial development. The cell-associated venoms are referred to as endotoxins and the extracellular diffusible venoms are referred to as exotoxins. The production of venom is generally limited to the specific bacterial species that produce the illness associated with the venom. The action of the bacterial toxin on host included: Plasma membrane permeabilization, labeling explicit atoms, Evacuating lipids, or lipid-tied down atoms, Examining intracellular courses. Knowledge of the venoms action mechanisms provide the basis to improve the vaccines and treatments to fight against bacterial pathogens to modified new protocols for using vaccine derivatives to treat human bacterial diseases. Bacterial venoms are now known as pathogens with their significant positive applications. Pathogenic bacteria have caused disease in humans for so long, and it is surprising that these pathogens still coexist and evolve with us regardless of an improved understanding of their pathogenicity and treatment. Protein toxins provide the bacteria with an advantage in host-pathogen interactions. Future studies of these protein toxins will expand our understanding of bacterial diseases and may identify new applications for these toxins as therapeutics for treating human disease.
Several microorganisms such as bacteria, algae, and fungi carry microbial toxins that evade molecular mechanisms. Microbial toxin exposure can impair the body’s immune system against pathogens. Their molecular weights range from a few thousand daltons (Da) to kilodaltons (kDa). Various microbes produce a variety of toxins, some of them cause mild to severe disease, while some toxins possess anticancer properties. Proteomics is applied to detect, discover, and differentiate toxins. This chapter gives an outline of microbial toxins and their analysis using various proteomics approaches. Advancement in proteomics has also advanced our knowledge of mechanisms of bacterial virulence and some crucial aspects of how bacteria interact with human cells and, thus, the pathogenesis of infectious diseases. These advancements include mass spectrometry (MS) technology, protein fractionation methods, and bioinformatics.
Bacterial toxins are pathogenicity factors that cause diseases for human and thread life of millions people worldwide. This occurs despite the extensive studies conducted to seek for approaches to ameliorate the damages caused by these toxins in the host cell. Therefore, this chapter review and integrate the different available information about bacterial toxins to develop comprehensive classification model, explore genetics insights and draw attention to the fact that bacterial toxins have useful therapeutics and biotechnological applications. The bacterial toxins are generally divided into exotoxin and endotoxin, which divided to four groups divided further to different families. Each of the four main classes uses the same mode of action to interact with the host cell. The genes encoding the different toxins located either in the bacterial chromosome or on the plasmid. In spite of the harmful effects of the bacterial toxins, they have different therapeutics and technological applications. For example, they can be used to treat some diseases, used in DNA sequencing and as biological weapons in biological warfare. However, more research required to classify the unclassified toxins and multidisciplinary research joint genetics and “Omics” approaches may help in deep understanding of the nature of the interaction between the bacterial toxins and the host cells, and assist in design and development of drugs and vaccines to neutralize the harmful effects of these toxins. Nevertheless, bacterial toxins can be abused as biological weapons therefore research focusing on enhancing the biodefence abilities of all world states is highly recommended.
Bovine mastitis remains a major disease in cattle world-wide. In the mammary gland, mammary epithelial cells (MEC) are sentinels equipped with receptors allowing them to detect and respond to the invasion by bacterial pathogens, in particular Escherichia coli . Lipopolysaccharide (LPS) is the major E. coli motif recognized by MEC through its interaction with the TLR4 receptor and the CD14 co-receptor. Previous studies have highlighted the role of soluble CD14 (sCD14) in the efficient recognition of LPS molecules possessing a full-length O-antigen (LPSS). We demonstrate here that MEC are able to secrete CD14 and are likely to contribute to the presence of sCD14 in milk. We then investigated how sCD14 modulates and is required for the response of MEC to LPSS. This study highlights the key role of sCD14 for the full activation of the Myd88-independent pathway by LPSS. We also identified several lncRNA that are activated in MEC in response to LPS, including one lncRNA showing homologies with the mir-99a-let-7c gene (MIR99AHG). Altogether, our results show that a full response to LPS by mammary epithelial cells requires sCD14 and provide detailed information on how milk sCD14 can contribute to an efficient recognition of LPS from coliform pathogens.
Ulcerative colitis (UC) is a chronic problem of the intestine and relapsing in nature. Biochanin A is a nature‐derived isoflavonoid and has numerous bioactivities. However, its role against UC and intestinal inflammation remains obscure. We aimed to comprehensively explore the pharmacological effect of biochanin A in alleviating colitis and to evaluate the potential mechanisms. Initially, we explored the anti‐inflammatory action of biochanin A (15, 30, and 60 μM) by employing lipopolysaccharide (LPS)‐activated RAW 264.7 cells. In RAW 264.7 cells under LPS stimulation, biochanin A inhibited the elevation of reactive oxygen species (ROS) ( p < 0.0001), interleukin (IL)−1β ( p < 0.0001), IL‐18 ( p < 0.01), and tumor necrosis factor (TNF)‐α ( p < 0.01) release, nitrite production ( p < 0.0001), and the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase‐2 (COX‐2) proteins. Next, we studied the effectiveness of biochanin A (20 and 40 mg/kg) in mouse colitis induced with dextran sulfate sodium (DSS) by assessing colon length, disease activity index (DAI) scoring, and performing colonoscopy and histological analysis. The pro‐inflammatory cytokines were estimated using ELISA. Western blot studies were performed to assess underlying mechanisms. In mice, biochanin A treatment alleviated DAI score ( p < 0.0001), restored colon length ( p < 0.05) and morphology, and re‐established colon histopathology. Biochanin A affects the phosphorylation of proteins associated with NF‐κB (p65) and mitogen‐activated protein kinase (MAPK) axis and regulates colonic inflammation by reducing the expression of inflammatory cytokines and myeloperoxidase (MPO) activity. Altogether, our findings support the idea that the anticolitis potential of biochanin A is allied with anti‐inflammatory activity by inhibiting the MAPK/NF‐κB (p65) axis. Hence, biochanin A may be an alternative option to alleviate the risk of colitis.
The urgent need to develop biocompatible, non-resistant antibacterial agents to effectively combat Gram-negative bacterial infections, particularly for the treatment of peritonitis, presents a significant challenge. In this study, we introduce our water-soluble Cu30 nanoclusters (NCs) as a potent and versatile antibacterial agent tailored for addressing peritonitis. The as-synthesized atomically precise Cu30 NCs demonstrate exceptional broad-spectrum antibacterial performance, and especially outstanding bactericidal activity of 100% against Gram-negative Escherichia coli (E. coli). Our in vivo experimental findings indicate that the Cu30 NCs exhibit remarkable therapeutic efficacy against primary peritonitis caused by E. coli infection. Specifically, the treatment leads to a profound reduction of drug-resistant bacteria in the peritoneal cavity of mice with peritonitis by more than 5 orders of magnitude, along with the resolution of pathological features in the peritoneum and spleen. Additionally, comprehensive in vivo biosafety assessment underscores the remarkable biocompatibility, low biotoxicity, as well as efficient hepatic and renal clearance of Cu30 NCs, emphasizing their potential for in vivo application. This investigation is poised to advance the development of novel Cu NC-based antibacterial agents for in vivo antibacterial treatment and the elimination of abdominal inflammation.
Intestinal damage and secondary bacterial translocation are caused by the inflammatory response induced by sepsis. Tongfu Lifei (TLF) decoction has a protective effect on sepsis-related gastrointestinal function injury. However, the relation between gut microbiota, immune barrier, and sepsis under the treatment of TLF have not been well clarified yet. Here, rats were subjected to cecal ligation and puncture (CLP) to create a sepsis model. Subsequently, the TLF decoction was given to CLP rats by gavage, fecal microbiota transplantation (FMT), and antibiotic were used as positive control. TLF suppressed the inflammatory response and improved the pathological changes in the intestines of CLP rats. Besides, TLF promoted the balance of the percentage of the Th17 and Treg cells. Intestinal barrier function was also improved by TLF through enhancing ZO-1, and Occludin and Claudin 1 expression, preventing the secondary translocation of other gut microbiota. TLF dramatically boosted the gut microbiota's alpha- and beta-diversity in CLP rats. Moreover, it increased the relative abundance of anti-inflammatory gut microbiota and changed the progress of the glucose metabolism. In short, TLF regulated the gut microbiota to balance the ratio of Th17/Treg cells, reducing the inflammation in serum and intestinal mucosal injury in rats.
Ultrasound has expanded into the therapeutic field as a medical imaging and diagnostic technique. Low-intensity pulsed ultrasound (LIPUS) is a kind of therapeutic ultrasound that plays a vital role in promoting fracture healing, wound repair, immunomodulation, and reducing inflammation. Its anti-inflammatory effects are manifested by decreased pro-inflammatory cytokines and chemokines, accelerated regression of immune cell invasion, and accelerated damage repair. Although the anti-inflammatory mechanism of LIPUS is not very clear, many in vitro and in vivo studies have shown that LIPUS may play its anti-inflammatory role by activating signaling pathways such as integrin/Focal adhesion kinase (FAK)/Phosphatidylinositol 3-kinase (PI3K)/Serine threonine kinase (Akt), Vascular endothelial growth factor (VEGF)/endothelial nitric oxide synthase (eNOS), or inhibiting signaling pathways such as Toll-like receptors (TLRs)/Nuclear factor kappa-B (NF-κB) and p38-Mitogen-activated protein kinase (MAPK). As a non-invasive physical therapy, the anti-inflammatory and immunomodulatory effects of LIPUS deserve further exploration.
In recent years, there has been a lot of interest in using nanotechnology in medicine to diagnose and cure various infectious diseases. Although the precise mechanism of action is frequently challenged, many nanosized materials have been extensively explored for this purpose, using their innately unique features. Their functionality has also been enhanced by the addition of various coatings, such as those that increase chemical stability and stealth properties or contain targeting agents that lessen off-target effects while producing effective "smart" nanoplatforms for the early detection, treatment, and possibly resolution of diseases.
This book aims to compile research and review articles that concentrate on the synthesis, characterization, and applications of nanomaterials, such as nanoparticles, with a focus on investigating novel ways to improve their properties and create new efficient diagnostic, therapeutic, or theranostic approaches with a clear understanding of how they work.
Background
Endometritis is an inflammatory reaction of the lining of uterus, leading to the occurrence of infertility. Platelet rich plasma (PRP) has been proven to exhibit extremely effective for the treatment of endometrium‐associated infertility, but the mechanism of its prevention for endometritis remains unclear.
Objective
The present study aimed to investigate the protective effect of PRP against endometritis induced by lipopolysaccharide (LPS) and elucidate the mechanism underlying these effects.
Methods
Mouse model of endometritis was established by intrauterine perfusion of LPS. PRP intrauterine infusion was administered at 24 h after LPS induction. After another 24 h, the uterine tissues were harvested to observe histopathological changes, production of proinflammatory cytokines, variation of the Toll‐like receptor 4/nuclear factor κB (TLR4/NF‐κB) signaling pathways, and validated the anti‐inflammatory effect of PRP. The myeloperoxidase (MPO) activity and concentration of nitric oxide (NO) were determined using assay kit. Proinflammatory chemokines (tumor necrosis factor‐α (TNF‐α), interleukin‐1β (IL‐1β), and interleukin‐6 (IL‐6)) were measured by ELISA and Real‐Time PCR. The activity of TLR4/NF‐κB pathway in uterine tissues was measured by Western blotting.
Results
Hematoxylin‐eosin staining (H&E) appeared that PRP remarkably relieved the impairment of uterine tissues. Detection of MPO activity and concentration of NO revealed that PRP treatment distinctly mitigated infiltration of inflammatory cells in mice with endometritis induced by LPS. PRP treatment significantly affected the expression of TNF‐α, IL‐1β, and IL‐6. PRP was also found to suppress LPS‐induced activation of TLR4/NF‐κB pathway.
Conclusion
PRP effectively alleviates LPS‐induced endometritis via restraining the signal pathway of TLR4/NF‐κB. These findings provide a solid foundation for PRP as a potential therapeutic agent for endometritis.
An immune reaction known as inflammation serves as a shield from external danger signals, but an overactive immune system may additionally lead to tissue damage and even a variety of inflammatory disorders. By inheriting biological functionalities and serving as both a therapeutic medication and a drug carrier, cell membrane‐based nanotherapeutics offer the potential to treat inflammatory disorders. To further strengthen the anti‐inflammatory benefits of natural cell membranes, researchers alter and optimize the membranes using engineering methods. This review focuses on engineered cell membrane‐based nanotherapeutics (ECMNs) and their application in treating inflammation‐related diseases. Specifically, this article discusses the methods of engineering cell membranes for inflammatory diseases and examines the progress of ECMNs in inflammation‐targeted therapy, inflammation‐neutralizing therapy, and inflammation‐immunomodulatory therapy. Additionally, the article looks into the perspectives and challenges of ECMNs in inflammatory treatment and offers suggestions as well as guidance to encourage further investigations and implementations in this area.
Intestinal mucositis (IM) is a common adverse effect of chemotherapy, limiting its clinical application. Edible Chinese medicine, specifically Codonopsis pilosula-derived CP-A, with anti-inflammatory and gastrointestinal protective effects. The present work was to investigate CP-A's role in ameliorating IM and its mechanism using in vitro and rat models. Western blot, immunohistochemical (IHC) and real-time PCR (RT-PCR) analyses were used to assess protein expression related to the extracellular-regulated protein kinases (ERK)/myosin light chain kinase (MLCK)/myosin light chain 2 (MLC2) signaling pathway and tight junction proteins. Enzyme-linked immunosorbent assay (ELISA) was conducted to measure inflammatory factors, and 16S rRNA Amplicon Sequencing was employed for cecum content analysis. The results indicated that CP-A could restore body weight, food intake and histopathological changes in IM rats. Besides, abnormal MLCK activation induced by 5-fluorouracil (5-FU) was attenuated by CP-A via the ERK/MLCK/MLC2 pathway. CP-A treatment improved tight junction protein levels and reduced inflammatory factor expression. On the other hand, intestinal flora experiment demonstrated that CP-A intervention could increase the abundance of lactobacillus. In conclusion, CP-A mitigates 5-FU-induced IM by inhibiting the ERK/MLCK/MLC2 pathway, reducing the expression of inflammatory factors, improving the intestinal mucosal barrier and regulating intestinal flora. This study sheds light on CP-A's therapeutic potential in IM treatment, providing insights for future research.
Se revisan algunos factores de virulencia de bacterias odontológicas
Tumor necrosis factor (TNF) is considered to be a pivotal mediator of endotoxin-induced lethality. To assess the intermediate role of TNF in specific systemic inflammatory responses known to contribute to tissue injury in endotoxemia, eight healthy adult chimpanzees were intravenously injected with Escherichia coli endotoxin (4 ng/kg). In four of these animals the administration of endotoxin was followed immediately by a bolus intravenous injection of an anti-TNF monoclonal antibody (15 mg/kg). Treatment with anti-TNF completely prevented the endotoxin-induced increase in serum TNF activity, and profoundly reduced the appearance of interleukin-6 and -8 (both P < .05). Neutrophilia and lymphopenia were not affected by anti-TNF, whereas neutrophil degranulation, as measured by the plasma concentrations of elastase-alpha 1-antitrypsin complexes, was only slightly reduced (peak levels after endotoxin alone 31.0 +/- 3.4 ng/mL, versus 25.5 +/- 3.4 ng/mL after endotoxin with anti-TNF; P < .05). Anti-TNF did not influence endotoxin-induced activation of the coagulation system, as reflected by unchanged increases in the plasma concentrations of the prothrombin fragment F1 + 2 and thrombin-antithrombin III complexes. In contrast, anti-TNF strongly attenuated the activation of the fibrinolytic system, ie, peak plasma levels of plasmin-alpha 2- antiplasmin were 33.8 +/- 11.1 nmol/L after endotoxin alone and 17.0 +/- 2.9 nmol/L after endotoxin with anti-TNF (P < .05). These results suggest that TNF is not the common mediator of systemic inflammatory changes in low-grade endotoxemia. Moreover, the finding that in this mild model anti-TNF specifically inhibited fibrinolysis suggests that treatment with anti-TNF potentially may enhance the tendency towards microvascular thrombosis in sepsis.
Significance
Superantigens—bacterial virulence factors—cause toxic shock by hyperinducing inflammatory cytokines. T-cell activation is mediated both by antigen and by interaction between principal costimulatory receptors B7-2 and CD28. Superantigens must bind CD28 to elicit cytokine overexpression through a hitherto unknown mechanism. We show that, by binding not only CD28 but also its coligand B7-2 directly, superantigens potently enhance the B7-2/CD28 interaction, thereby inducing T-cell hyperactivation. Superantigens engage B7-2 and CD28 at their homodimer interfaces, far from where the receptors interact, demonstrating the regulatory properties of these interfaces. B7-2 dimer interface peptides attenuate cytokine overexpression and prevent superantigen lethality by blocking costimulatory receptor engagement by superantigen. Thus, bacterial superantigens induce a pathogenic “cytokine storm” by strongly enhancing formation of the B7-2/CD28 costimulatory axis.
Streptococcus pneumoniae (the pneumococcus) is capable of invading the heart. Herein we observed that pneumococcal invasion of the myocardium occurred
soon after and was continuous during a bacteremia episode. Using immunofluorescent microscopy (IFM) we observed that S. pneumoniae replication within the heart preceded visual signs of tissue damage in H&E stained cardiac sections. Different S. pneumoniae strains caused distinct cardiac pathology: strain TIGR4, a serotype 4 isolate, caused discrete pneumococci-filled microscopic
lesions (microlesions), whereas strain D39, a serotype 2 isolate, was in most instances only detectable using IFM and was
associated with foci of cardiomyocyte hydropic degeneration and immune cell infiltration. Both strains invaded the myocardium
efficiently, but only for D39 was cardiac damage entirely dependent on the pore-forming toxin pneumolysin. Early microlesions
caused by TIGR4 and microlesions formed by a TIGR4 pneumolysin deficient mutant formed microlesions filled with infiltrated
CD11b+/Ly6G+ neutrophils and CD11b+/F480+ macrophages. Subsequently, we demonstrated that macrophages in TIGR4-infected hearts were dying as a result of pneumolysin-induced
necroptosis. The effector of necroptosis, phosphorylated MLKL, was detected in CD11b++/F480+ cells associated with microlesions. Likewise, treatment of infected mice and THP-1 macrophages in vitro with the RIP1 kinase inhibitor necrostatin-5 promoted formation of purulent microlesions and blocked cell death, respectively.
We conclude that invaded pneumococci are an important cause of cardiac damage, pneumolysin contributes to cardiac damage in
a bacterial strain-specific manner, and that pneumolysin kills infiltrated macrophages via necroptosis and this alters the
immune response.
The inflammasomes are intracellular protein complexes that play an important role in innate immune sensing. Activation of inflammasomes leads to activation of caspase-1 and maturation and secretion of the pro-inflammatory cytokines interleukin (IL)-1β and IL-18. In certain myeloid cells, this activation can also lead to an inflammatory cell death (pyroptosis). Inflammasome sensor proteins have evolved to detect a range of microbial ligands and bacterial exotoxins either through direct interaction or by detection of host cell changes elicited by these effectors. Bacterial exotoxins activate the inflammasomes through diverse processes, including direct sensor cleavage, modulation of ion fluxes through plasma membrane pore formation, and perturbation of various host cell functions. In this review, we summarize the findings on some of the bacterial exotoxins that activate the inflammasomes.
Innate immunity instructs adaptive immunity, and suppression of innate immunity is associated with an increased risk for infection. We showed previously that whole-blood cellular components from a cohort of South African children secreted significantly lower levels of most cytokines following stimulation of pattern recognition receptors compared with whole blood from cohorts of Ecuadorian, Belgian, or Canadian children. To begin dissecting the responsible molecular mechanisms, we set out to identify the relevant cellular source of these differences. Across the four cohorts represented in our study, we identified significant variation in the cellular composition of whole blood; however, a significant reduction in the intracellular cytokine production on the single-cell level was only detected in South African children's monocytes, conventional dendritic cells, and plasmacytoid dendritic cells. We also uncovered a marked reduction in polyfunctionality for each of these cellular compartments in South African children compared with children from the other continents. Together, our data identify differences in cell composition, as well as profoundly lower functional responses of innate cells, in our cohort of South African children. A possible link between altered innate immunity and increased risk for infection or lower response to vaccines in South African infants needs to be explored.
Cytosolic inflammasome complexes mediated by a pattern recognition receptor (PRR) defend against pathogen infection by activating caspase 1. Pyrin, a candidate PRR, can bind to the inflammasome adaptor ASC to form a caspase 1-activating complex. Mutations in the Pyrin-encoding gene, MEFV, cause a human autoinflammatory disease known as familial Mediterranean fever. Despite important roles in immunity and disease, the physiological function of Pyrin remains unknown. Here we show that Pyrin mediates caspase 1 inflammasome activation in response to Rho-glucosylation activity of cytotoxin TcdB, a major virulence factor of Clostridium difficile, which causes most cases of nosocomial diarrhoea. The glucosyltransferase-inactive TcdB mutant loses the inflammasome-stimulating activity. Other Rho-inactivating toxins, including FIC-domain adenylyltransferases (Vibrio parahaemolyticus VopS and Histophilus somni IbpA) and Clostridium botulinum ADP-ribosylating C3 toxin, can also biochemically activate the Pyrin inflammasome in their enzymatic activity-dependent manner. These toxins all target the Rho subfamily and modify a switch-I residue. We further demonstrate that Burkholderia cenocepacia inactivates RHOA by deamidating Asn 41, also in the switch-I region, and thereby triggers Pyrin inflammasome activation, both of which require the bacterial type VI secretion system (T6SS). Loss of the Pyrin inflammasome causes elevated intra-macrophage growth of B. cenocepacia and diminished lung inflammation in mice. Thus, Pyrin functions to sense pathogen modification and inactivation of Rho GTPases, representing a new paradigm in mammalian innate immunity.
Subtilase cytotoxin (SubAB) is the prototype of a recently emerged family of AB5 cytotoxins produced by Shiga-toxigenic Escherichia coli (STEC). Its mechanism of action involves highly specific A-subunit-mediated proteolytic cleavage of the essential endoplasmic
reticulum (ER) chaperone BiP. Our previous in vivo studies showed that intraperitoneal injection of purified SubAB causes a major redistribution of leukocytes and elevated
leukocyte apoptosis in mice, as well as profound splenic atrophy. In the current study, we investigated selected chemokine
and proinflammatory cytokine responses to treatment with SubAB, a nontoxic derivative (SubAA272B), or Shiga toxin 2 (Stx2) in human macrophage (U937), brain microvascular endothelial (HBMEC), and colonic epithelial (HCT-8)
cell lines, at the levels of secreted protein, cell-associated protein, and gene expression. Stx2 treatment upregulated expression
of chemokines and cytokines at both the protein and mRNA levels. In contrast, SubAB induced significant decreases in secreted
interleukin-8 (IL-8) and monocyte chemoattractant protein 1 (MCP-1) in all three tested cell lines and a significant decrease
in secreted IL-6 in HBMECs. The downregulation of secreted chemokines or cytokines was not observed in SubAA272B-treated cells, indicating a requirement for BiP cleavage. The downregulation of secreted chemokines and cytokines by SubAB
was not reflected at the mRNA and cell-associated protein levels, suggesting a SubAB-induced export defect.
Transendothelial migration of neutrophils in postcapillary venules is a key event in the inflammatory response against pathogens and tissue damage. The precise regulation of this process is incompletely understood. We report that perivascular macrophages are critical for neutrophil migration into skin infected with the pathogen Staphylococcus aureus. Using multiphoton intravital microscopy we showed that neutrophils extravasate from inflamed dermal venules in close proximity to perivascular macrophages, which are a major source of neutrophil chemoattractants. The virulence factor α-hemolysin produced by S. aureus lyses perivascular macrophages, which leads to decreased neutrophil transmigration. Our data illustrate a previously unrecognized role for perivascular macrophages in neutrophil recruitment to inflamed skin and indicate that S. aureus uses hemolysin-dependent killing of these cells as an immune evasion strategy.
Murine macrophages have been classified as either susceptible or nonsusceptible to killing by anthrax lethal toxin (LT) depending upon genetic background. While considered resistant to LT killing, we found that bone marrow-derived macrophages (BMMs) from DBA/2, AKR, and C57BL/6 mice were slowly killed by apoptosis following LT exposure. LT killing was not restricted to in vitro assays, as splenic macrophages were also depleted in LT-injected C57BL/6 mice. Human macrophages, also considered LT resistant, similarly underwent slow apoptosis in response to LT challenge. In contrast, LT triggered rapid necrosis and a broad protein release in BMMs derived from BALB/c and C3H/HeJ, but not C57BL/6 mice. Released proteins included processed interleukin-18, confirming reports of inflammasome and caspase-1 activation in LT-mediated necrosis in macrophages. Complete inhibition of caspase-1 activity was required to block LT-mediated necrosis. Strikingly, minimal residual caspase-1 activity was sufficient to trigger significant necrosis in LT-treated macrophages, indicating the toxicity of caspase-1 in this process. IL-18 release does not trigger cytolysis, as IL-18 is released late and only from LT-treated macrophages undergoing membrane perturbation. We propose that caspase-1-mediated macrophage necrosis is the source of the cytokine storm and rapid disease progression reported in LT-treated BALB/c mice.
Administration of non-lethal doses of lipopolysaccharide (LPS) to experimental animals and humans results for a short period of time in a state of hyporesponsiveness to a second LPS challenge. This phenomenon, known as endotoxin tolerance, has been reproduced in vitro using human monocytes, rendered endotoxin-tolerant following a first incubation with LPS. A further activation by LPS was manifested by a dramatically reduced production of tumor necrosis factor α (TNFα). We report this low responsiveness of LPS pretreated monocytes as an endotoxin non-specific phenomenon. Indeed, TNFα release upon further activation with either killed Gram-positive bacteria (Staphylococci, Streptococci) or zymosan was also significantly diminished. This was not the case when phorbol myristate acetate (PMA) was used as a second triggering agent, suggesting that the monocyte hyporesponsiveness due to LPS does not affect all activation pathways, particularly that of protein kinase C. On the other hand, both PMA and zymosan pretreatment could reduce a further activation of monocytes by LPS. We investigated whether the first signal(s) delivered by LPS, could be mimicked by some of the LPS-induced cytokines. Preincubation of monocytes with either interleukin-1 (IL-1), IL-10 or transforming growth factor β (TGFβ) lower the TNFα production upon further activation with LPS. None of the cytokines alone was as efficient as the LPS molecule, but high levels of tolerization were obtained with combination of IL-1, IL-10 and TGFβ. Neither IL-6, IL-8 nor TNFα led to hyporeactive cells. Our data indicate that endotoxin tolerance is not an LPS-specific phenomenon and that more than one cytokine can contribute to render human monocytes hyporeactive to further activation by LPS.
SUMMARY This review begins with a discussion of the large family of Staphylococcus aureus and beta-hemolytic streptococcal pyrogenic toxin T lymphocyte superantigens from structural and immunobiological perspectives. With this as background, the review then discusses the major known and possible human disease associations with superantigens, including associations with toxic shock syndromes, atopic dermatitis, pneumonia, infective endocarditis, and autoimmune sequelae to streptococcal illnesses. Finally, the review addresses current and possible novel strategies to prevent superantigen production and passive and active immunization strategies.
Caspase-1 activation by inflammasome scaffolds comprised of intracellular nucleotide-binding oligomerization domain (NOD)-like receptors (NLRs) and the adaptor ASC is believed to be essential for production of the pro-inflammatory cytokines interleukin (IL)-1β and IL-18 during the innate immune response. Here we show, with C57BL/6 Casp11 gene-targeted mice, that caspase-11 (also known as caspase-4) is critical for caspase-1 activation and IL-1β production in macrophages infected with Escherichia coli, Citrobacter rodentium or Vibrio cholerae. Strain 129 mice, like Casp11(-/-) mice, exhibited defects in IL-1β production and harboured a mutation in the Casp11 locus that attenuated caspase-11 expression. This finding is important because published targeting of the Casp1 gene was done using strain 129 embryonic stem cells. Casp1 and Casp11 are too close in the genome to be segregated by recombination; consequently, the published Casp1(-/-) mice lack both caspase-11 and caspase-1. Interestingly, Casp11(-/-) macrophages secreted IL-1β normally in response to ATP and monosodium urate, indicating that caspase-11 is engaged by a non-canonical inflammasome. Casp1(-/-)Casp11(129mt/129mt) macrophages expressing caspase-11 from a C57BL/6 bacterial artificial chromosome transgene failed to secrete IL-1β regardless of stimulus, confirming an essential role for caspase-1 in IL-1β production. Caspase-11 rather than caspase-1, however, was required for non-canonical inflammasome-triggered macrophage cell death, indicating that caspase-11 orchestrates both caspase-1-dependent and -independent outputs. Caspase-1 activation by non-canonical stimuli required NLRP3 and ASC, but caspase-11 processing and cell death did not, implying that there is a distinct activator of caspase-11. Lastly, loss of caspase-11 rather than caspase-1 protected mice from a lethal dose of lipopolysaccharide. These data highlight a unique pro-inflammatory role for caspase-11 in the innate immune response to clinically significant bacterial infections.
Bacterial superantigens are Gram-positive exotoxins that induce proinflammatory cytokine release in vitro, cause lethal shock in vivo, and can be detected in the bloodstream of critically ill patients. They also have a powerful priming effect on the TLR4 agonist LPS. The aim of this study was to investigate the relationship between superantigens and the TLR2 agonist bacterial lipoprotein (BLP). Priming of human monocytes or PBMCs with superantigens significantly enhanced proinflammatory cytokine TNF-α and IL-6 release in response to BLP stimulation. The priming effect of superantigens could be blocked by inhibiting p38 MAPK during the priming phase as opposed to NF-κB or ERK inhibition. This was consistent with higher expression of the phosphorylated p38 after superantigen priming and BLP or LPS stimulation. C57BL/6 mice with superantigen priming (10 μg/mouse) when challenged with BLP (600 μg/mouse) exhibited substantially higher mortality (100%) compared with mice without superantigen priming (zero). Mice given superantigen alone did not demonstrate any signs of illness. Mice challenged with both superantigen and BLP had significantly higher levels of serum TNF-α and IL-6 compared with those of mice challenged with either agent alone. Depletion of the monocyte/macrophage subpopulation significantly reduced the mortality rate from 100 to 20% in superantigen-primed, BLP-challenged C57BL/6 mice, with a 5- to 10-fold decrease in serum TNF-α and IL-6. Our results demonstrate that bacterial superantigens enhance the in vitro proinflammatory cytokine release and in vivo lethality of BLP. This novel finding may help to explain the massive proinflammatory cytokine release seen in superantigen-mediated septic shock.
Staphylococcal enterotoxin (SE) -induced toxic shock is triggered by inflammatory cytokine signal amplification after SE binding to major histocompatibility complex class II molecules on antigen-presenting cells and T-cell receptors. Identifying host cellular elements contributing to this pro-inflammatory signal amplification is critical for developing a strategy for therapeutic intervention. Myeloid differentiation primary-response protein 88 (MyD88) is an intracellular signalling adaptor protein primarily known for mediating pro-inflammatory cytokine responses. We investigated the role of MyD88 in staphylococcal enterotoxin A (SEA) -treated cell cultures and mouse models of toxic shock. Our results demonstrated that elevated levels of tumour necrosis factor-alpha, interferon-gamma, interleukin-1alpha/beta (IL-1alpha/beta), IL-2 and IL-6 production correlated with up-regulation of MyD88 after treatment of spleen cells and mice with SEA alone or in combination with lipopolysaccharide (LPS). The SEA-induced lethality was also observed in (LPS-independent) D-galactosamine-sensitized mice. While LPS potentiated SEA-induced cytokine responses, D-galactosamine treatment had no additive effect. Most importantly, our results demonstrated that MyD88(-/-) mice were resistant to SEA-induced toxic shock and had reduced pro-inflammatory cytokine responses. These results suggest that SEA-induced lethality is primarily dependent on MyD88. Our findings offer an important insight on potential therapeutic treatment of SEA-induced toxic shock targeting MyD88.
Bacteremia is recognized as a critical condition that influences the outcome of sepsis. Although large-scale surveillance studies of bacterial species causing bacteremia have been published, the pathophysiological differences in bacteremias with different causative bacterial species remain unclear. The objective of the present study is to investigate the differences in pathophysiology and the clinical course of bacteremia caused by different bacterial species.
We reviewed the medical records of all consecutive patients admitted to the general intensive care unit (ICU) of a university teaching hospital during the eight-year period since introduction of a rapid assay for interleukin (IL)-6 blood level to routine ICU practice in May 2000. White blood cell count, C-reactive protein (CRP), IL-6 blood level, and clinical course were compared among different pathogenic bacterial species.
The 259 eligible patients, as well as 515 eligible culture-positive blood samples collected from them, were included in this study. CRP, IL-6 blood level, and mortality were significantly higher in the septic shock group (n = 57) than in the sepsis group (n = 127) (P < 0.001). The 515 eligible culture-positive blood samples harbored a total of 593 isolates of microorganisms (Gram-positive, 407; Gram-negative, 176; fungi, 10). The incidence of Gram-negative bacteremia was significantly higher in the septic shock group than in the sepsis group (P < 0.001) and in the severe sepsis group (n = 75, P < 0.01). CRP and IL-6 blood level were significantly higher in Gram-negative bacteremia (n = 176) than in Gram-positive bacteremia (n = 407) (P < 0.001, <0.0005, respectively).
The incidence of Gram-negative bacteremia was significantly higher in bacteremic ICU patients with septic shock than in those with sepsis or severe sepsis. Furthermore, CRP and IL-6 levels were significantly higher in Gram-negative bacteremia than in Gram-positive bacteremia. These findings suggest that differences in host responses and virulence mechanisms of different pathogenic microorganisms should be considered in treatment of bacteremic patients, and that new countermeasures beyond conventional antimicrobial medications are urgently needed.
Vertebrates vary in resistance and resilience to infectious diseases, and the mechanisms that regulate the tradeoff between
these often opposing protective processes are not well understood. Variability in the sensitivity of species to the induction
of damaging inflammation in response to equivalent pathogen loads (resilience) complicates the use of animal models that reflect
human disease. We found that induction of proinflammatory cytokines from macrophages in response to inflammatory stimuli in
vitro is regulated by proteins in the sera of species in inverse proportion to their in vivo resilience to lethal doses of
bacterial lipopolysaccharide over a range of 10,000-fold. This finding suggests that proteins in serum rather than intrinsic
cellular differences may play a role in regulating variations in resilience to microbe-associated molecular patterns between
species. The involvement of circulating proteins as key molecules raises hope that the process might be manipulated to create
better animal models and potentially new drug targets.
A series of observations on the blood of patients acutely ill with scarlet fever has shown that a toxic substance can be demonstrated in the serum by means of intracutaneous injections of the serum in persons who have not had scarlet fever and whose serums fail to blanch the rash in scarlet fever. The reaction caused by this substance consists of a bright red local erythema, varying from 20 to 70 mm. in diameter, of 1 to 4 days duration. The severer reactions are moderately indurated and tender, and are followed bypigmentation and desquamation. Control injections in persons whose serums blanch the rash in scarlet fever cause no reaction. The toxic substance is not neutralized by mixture with a human serum which gives a negative blanching test but is readily neutralized by a human serum which gives a positive blanching test. It is not neutralized by normal horse serum, but is completely neutralized by Dochez's scarlatinal antistreptococcic serum. In a limited number of observations on the urine of patients with scarlet fever a similar toxic substance has been found in two out of five cases studied. Since the toxic substance described appears to resemble the toxic substance found in the filtrates of scarlatinal hemolytic streptococcus cultures by Dick and Dick and since it is neutralized not only by a blanching human serum but also by Dochez's scarlatinal antistreptococcic horse serum, the experiments reported support the conception that scarlet fever is a local infection of the throat by a particular type of Streptococcus haemolyticus capable of producing a toxin which is absorbed and is the cause of the general manifestations of the disease.
Sepsis and trauma are both leading causes of death in the United States and represent major public health challenges. Murine models have largely been used in sepsis and trauma research to better understand the pathophysiological changes that occur after an insult and to develop potential life-saving therapeutic agents. Mice are favorable subjects for this type of research given the variety of readily available strains including inbred, outbred, and transgenic strains. In addition, they are relatively easy to maintain and have a high fecundity. However, pharmacological therapies demonstrating promise in preclinical mouse models of sepsis and trauma often fail to demonstrate similar efficacy in human clinical trials, prompting considerable criticism surrounding the capacity of murine models to recapitulate complex human diseases like sepsis and traumatic injury. Fundamental differences between the two species include, but are not limited to, the divergence of the transcriptomic response, the mismatch of temporal response patterns, differences in both innate and adaptive immunity, and heterogeneity within the human population in comparison to the homogeneity of highly inbred mouse strains. Given the ongoing controversy, this narrative review aims to not only highlight the historical importance of the mouse as an animal research model but also highlight the current benefits and limitations of the model as it pertains to sepsis and trauma. Lastly, this review will propose future directions that may promote further use of the model.
In the article "The staphylococcal enterotoxins and their relatives" by Philippa Marrack and John Kappler (11 May, p. 705), figures 1, 2, and 3 were incorrectly printed. The color portions of figures 2 and 3 should have been included in figure 1. The correct figure 1 is printed below. See image in PDF file
Toxic shock syndrome (TSS) is caused by staphylococcal and streptococcal superantigens (SAgs) that provoke a swift hyperinflammatory response typified by a cytokine storm. The precipitous decline in the host's clinical status and the lack of targeted therapies for TSS emphasize the need to identify key players of the storm's initial wave. Using a humanized mouse model of TSS and human cells, we herein demonstrate that SAgs elicit in vitro and in vivo IL-17A responses within hours. SAg-triggered human IL-17A production was characterized by remarkably high mRNA stability for this cytokine. A distinct subpopulation of CD4+ effector memory T (TEM) cells that secrete IL-17A, but not IFN-γ, was responsible for early IL-17A production. We found mouse "TEM-17" cells to be enriched within the intestinal epithelium and among lamina propria lymphocytes. Furthermore, interfering with IL-17A receptor signaling in human PBMCs attenuated the expression of numerous inflammatory mediators implicated in the TSS-associated cytokine storm. IL-17A receptor blockade also abrogated the secondary effect of SAg-stimulated PBMCs on human dermal fibroblasts as judged by C/EBP δ expression. Finally, the early IL-17A response to SAgs was pathogenic because in vivo neutralization of IL-17A in humanized mice ameliorated hepatic and intestinal damage and reduced mortality. Together, our findings identify CD4+ TEM cells as a key effector of TSS and reveal a novel role for IL-17A in TSS immunopathogenesis. Our work thus elucidates a pathogenic, as opposed to protective, role for IL-17A during Gram-positive bacterial infections. Accordingly, the IL-17-IL-17R axis may provide an attractive target for the management of SAg-mediated illnesses.
Pathogenic Yersinia, including Y. pestis, the agent of plague in humans, and Y. pseudotuberculosis, the related enteric pathogen, deliver virulence effectors into host cells via a prototypical type III secretion system to promote pathogenesis. These effectors, termed Yersinia outer proteins (Yops), modulate multiple host signaling responses. Studies in Y. pestis and Y. pseudotuberculosis have shown that YopM suppresses infection-induced inflammasome activation; however, the underlying molecular mechanism is largely unknown. Here we show that YopM specifically restricts the pyrin inflammasome, which is triggered by the RhoA-inactivating enzymatic activities of YopE and YopT, in Y. pseudotuberculosis-infected macrophages. The attenuation of a yopM mutant is fully reversed in pyrin knockout mice, demonstrating that YopM inhibits pyrin to promote virulence. Mechanistically, YopM recruits and activates the host kinases PRK1 and PRK2 to negatively regulate pyrin by phosphorylation. These results show how a virulence factor can hijack host kinases to inhibit effector-triggered pyrin inflammasome activation.
Interleukin-1β (IL-1β) is a key proinflammatory cytokine that drives antimicrobial immune responses. IL-1β is aberrantly activated in autoimmune diseases, and IL-1β inhibitors are used as therapeutic agents to treat patients with certain autoimmune disorders. Review of postmarketing surveillance of patients receiving IL-1β inhibitors found a disproportionate reporting of invasive infections by group A Streptococcus (GAS). IL-1β inhibition increased mouse susceptibility to GAS infection, but IL-1β was produced independent of canonical inflammasomes. Newly synthesized IL-1β has an amino-terminal prodomain that blocks signaling activity, which is usually proteolytically removed by caspase-1, a protease activated within the inflammasome structure. In place of host caspases, the secreted GAS cysteine protease SpeB generated mature IL-1β. During invasive infection, GAS isolates may acquire pathoadaptive mutations eliminating SpeB expression to evade detection by IL-1β. Pharmacological IL-1β inhibition alleviates this selective pressure, allowing invasive infection by nonpathoadapted GAS. Thus, IL-1β is a sensor that directly detects pathogen-associated proteolysis through an independent pathway operating in parallel with host inflammasomes. Because IL-1β function is maintained across species, yet cleavage by caspases does not appear to be, detection of microbial proteases may represent an ancestral system of innate immune regulation.
Endotoxins isolated from Gram negative bacteria can induce profound physiological modifications and trigger the immune system. Endotoxins are lipopolysaccharides (LPS) which consist of a polysaccharide chain (PS) covalently linked to a hydrophobic moiety (Lipid A) via a 2-keto-3-deoxy-octonic acid residue(s) (KDO). The classical endotoxic activities (e.g. local Shwartzman reaction, pyrogenicity, lethality…) as well as the immunological effects of endotoxins (adjuvanticity, mitogenicity, polyclonal activation of immunoglobulin secreting cells…) are mediated by the Lipid A (1,2). However, it has also been shown that the polysaccharide moiety of some LPS act as an adjuvant (3,4); protect mice against lethal irradiation (5,6); induce the production of colony stimulating factors (5–8); induce a “transfer tumor resistance” in serum of BCG-infected mice (9); and mediate B-cell proliferation (10). LPS can also stimulate complex positive and negative immunoregulatory circuits in which monocytes/macrophages play a central role (10–14).
Burkholderia cenocepacia is an opportunistic pathogen of the cystic fibrosis lung that elicits a strong inflammatory response. B. cenocepacia employs a type VI secretion system (T6SS) to survive in macrophages by disarming Rho-type GTPases, causing actin cytoskeletal defects. Here, we identified TecA, a non-VgrG T6SS effector responsible for actin disruption. TecA and other bacterial homologs bear a cysteine protease-like catalytic triad, which inactivates Rho GTPases by deamidating a conserved asparagine in the GTPase switch-I region. RhoA deamidation induces caspase-1 inflammasome activation, which is mediated by the familial Mediterranean fever disease protein Pyrin. In mouse infection, the deamidase activity of TecA is necessary and sufficient for B. cenocepacia-triggered lung inflammation and also protects mice from lethal B. cenocepacia infection. Therefore, Burkholderia TecA is a T6SS effector that modifies a eukaryotic target through an asparagine deamidase activity, which in turn elicits host cell death and inflammation through activation of the Pyrin inflammasome. Burkholderia cenocepacia is highly proinflammatory and causes severe lung infection in cystic fibrosis patients. Aubert et al. identify a type VI effector, TecA, in B. cenocepacia that disrupts macrophage actin cytoskeleton by deamidating Rho GTPases. The action of TecA is detected by the Pyrin inflammasome, which triggers inflammation in mice.
Three years ago, at a meeting of this body in Baltimore, a paper was read upon a similar subject by a distinguished surgeon. In that paper, based upon a personal experience of nine cases, three of which were carcinoma and a large proportion of the remainder types of sarcoma, which I had myself regarded as unfavorable, the broad generalization was made that the method was of no value, and the prophecy was ventured that in one year from that date it would be forgotten and buried in that oblivion that has furnished a quiet resting-place for so many of the brilliant cancer cures that have from time to time dotted the medical history of the past.
Oligonucleotide and complementary DNA microarrays are being used to subclassify histologically similar tumours, monitor disease progress, and individualize treatment regimens. However, extracting new biological insight from high-throughput genomic studies of human diseases is a challenge, limited by difficulties in recognizing and evaluating relevant biological processes from huge quantities of experimental data. Here we present a structured network knowledge-base approach to analyse genome-wide transcriptional responses in the context of known functional interrelationships among proteins, small molecules and phenotypes. This approach was used to analyse changes in blood leukocyte gene expression patterns in human subjects receiving an inflammatory stimulus (bacterial endotoxin). We explore the known genome-wide interaction network to identify significant functional modules perturbed in response to this stimulus. Our analysis reveals that the human blood leukocyte response to acute systemic inflammation includes the transient dysregulation of leukocyte bioenergetics and modulation of translational machinery. These findings provide insight into the regulation of global leukocyte activities as they relate to innate immune system tolerance and increased susceptibility to infection in humans.
We present evidence that toxic shock syndrome toxin 1 (TSST-1) induces the production of high levels of TNF by human blood monocytes. Enriched lymphocyte preparations incubated with the staphylococcal toxin produced significant levels of TNF-like activity that is not neutralized by anti-rHuTNF antibodies and is likely to be lymphotoxin (LT or TNF-beta). We demonstrate also that TSST-1 is a potent inducer of IFN-gamma. When lymphocyte preparations were costimulated with PMA, the TSST-1 effect was strongly potentiated and the levels of cytotoxic factors, IFN-gamma, and IL-2 present in supernatant fluids were comparable to those observed after treatment with PMA and PHA. Thus, TSST-1, which is also known as an inducer of IL-1 and IL-2, stimulates the production of endogenous mediators that could play a role in the physiopathological processes of toxic shock syndrome (TSS). The described results suggest that the discrepancies in the clinical features between TSS and endotoxin shock may be related to qualitative differences in cytokine production.
Because mice are more resistant than humans to the pathogenic effects of bacterial toxins, we used D-Galactosamine- (D-Gal) sensitized mice as a model system to evaluate potential toxic shock symptoms triggered by the superantigen staphylococcal enterotoxin B (SEB). We show that similar to endotoxin (lipopolysaccharide) [LPS], the exotoxin SEB causes lethal shock within 8 h in D-Gal-sensitized mice, inducing 100% and about 50% lethality with 20 and 2 micrograms SEB, respectively. The lethal shock triggered by the superantigen SEB is mediated by T cells, a conclusion based on the observation that T cell repopulation of SCID mice conferred sensitivity to SEB. Since CSA also conferred protection, the role of T cell-derived lymphokines in mediating lethal shock was evaluated. Within 30-60 min after SEB injection, serum tumor necrosis factor (TNF) levels peaked, followed immediately by interleukin-2 (IL-2). Serum-borne lymphokines were detected well in advance of signs of T cell activation, as assessed by IL-2 receptor expression of SEB-reactive V beta 8+ T cells. Passive immunization with anti-TNF-alpha/beta-neutralizing monoclonal antibody also conferred protection, indicating that it is TNF which is critical for initiating toxic shock symptoms. Taken together, this study defines basic differences between endotoxin (LPS)- and exotoxin (SEB)-mediated lethal shock, in that the former is mediated by macrophages and the latter by T cells. Yet the pathogenesis distal to the lymphokine/cytokine-producing cells appears surprisingly similar in that TNF represents a key mediator in inducing shock.
Interleukin (IL)-6, IL-1 beta, and tumor necrosis factor alpha (TNF-alpha) are considered to act as endogenous pyrogens. Because of the complex pattern of cross-inductions between these cytokines, the relative role of the central and peripheral production of these cytokines in eliciting the fever response has not yet been clarified. The purpose of this study was to determine the role of IL-6 in the fever response by making use of mice carrying a null mutation in the IL-6 gene. The intraperitoneal injections of lipopolysaccharide (LPS) (50 micrograms/kg) and recombinant murine (rm) IL-1 beta (10 micrograms/kg), respectively, failed to evoke fever response in IL-6-deficient mice, whereas the same doses of LPS and rmIL-1 beta caused fever response in wild-type mice. The fever response could be induced in the IL-6-deficient mice by intracerebroventricular injection of recombinant human (rh) IL-6 (500 ng/mouse), whereas intracerebroventricular injection of rmIL-1 beta (100 ng/mouse) failed to produce fever response in the IL-6-deficient mice. These results suggest that central IL-6 is a necessary component of the fever response to both endogenous (IL-1 beta) and exogenous (LPS) pyrogens in mice and that IL-6 acts downstream from both peripheral and central IL-1 beta.
We had previously shown that the specific binding of endotoxin (lipopolysaccharide, LPS) to human monocytes in the presence of serum was mediated by the polysaccharide moiety of the LPS molecule. CD14 has been identified as the main receptor for endotoxin on monocytes/macrophages. In the present report we demonstrate that the CD14 molecule exhibits lectin-like properties. Anti-CD14 monoclonal antibodies inhibited the binding of [3H]-radiolabeled Neisseria meningitidis LPS as efficiently as the homologous unlabeled LPS. Rough Escherichia coli LPS (Rc- and Re-types) could also inhibit the binding of [3H]-LPS to a similar extent, whereas lipid A had no or very weak inhibitory activity. This suggests a major contribution of the inner-core region within the LPS and particularly the Kdo sugars. The lectin-like nature of CD14 was assessed with polyanionic sugars as well as with uncharged polysaccharides. The relative efficiencies in competition were dextran sulfate > fucoidan > mannan > polygalacturonic acid = heparan sulfate ≥ heparin ≥ chondroitin sulfate. Candida albicans phospholipomannan was far more active in the competition experiment than the mannan, indicating that, besides the osidic residues, anionic charges and/or fatty acids may contribute to the interaction with the CD14 molecule. Binding of polysaccharide to CD14 was not sufficient to trigger TNFα and IL-6 production since phospholipomannan and dextran sulfate were unable to induce cytokine release. Taken together, these results demonstrate that the binding of [3H]-LPS to CD14 involves the contribution of sugars and suggest that the signals for cytokine production require additional interactions.
We report on the genetic effect onin vivoproduction of tumor necrosis factor (TNF)-α induced by lipopolysaccharides (LPS) using various congenic mouse strains. B10.A, B10.A(3R), B10.AQR, B10.A(5R), and B10.S(7R) produced significantly high TNF-α compared with B10.BR, B10.S, C57BL/10, B10.A(2R), B10.A(4R), B10.G, B10.DA(80NS), and B10.RIII(71NS). This suggests that LPS-induced TNF-α production is genetically controlled by H-2. Mice with the same alleles on K, A, E, or S loci produced various (high or low) levels of TNF-α, thus indicating that regulatory genes are located outside these loci. All strains with H-2Ddproduced significantly high levels of TNF-α, but strains with other alleles in the H-2D locus produced low levels. Thus, TNF-α production appears to be genetically linked to H-2D itself or H-2D linked genes and the allele d is linked to a high responder gene. This was the case with the A background. C3H/HeN (H-2k), however, showed a high TNF-α production, suggesting the presence of another controlling gene outside H-2. In addition, high TNF-α productivity was transmitted into F1 mice (B10.A × B10.BR) in a dominant fashion. Both LPS-stimulated and unstimulated TNF-α mRNA expression in splenic macrophages were enhanced in high responder strains. Thus, we conclude that TNF-α production is closely related to genes within or linked to the H-2D locus as well as others outside H-2.
The discovery of Toll-like receptors (TLRs) was an important event for immunology research and was recognized as such with the awarding of the 2011 Nobel Prize in Physiology or Medicine to Jules Hoffmann and Bruce Beutler, who, together with Ralph Steinman, the third winner of the 2011 Nobel Prize and the person who discovered the dendritic cell, were pioneers in the field of innate immunity. TLRs have a central role in immunity - in this Timeline article, we describe the landmark findings that gave rise to this important field of research.
After the production of experimental scarlet fever,1 it was demonstrated that Berkefeld W filtrates of the hemolytic streptococcus, used in the successful inoculations, contain a toxic substance. When injected intracutaneously, in the proper dilution, this substance gives skin reactions that can be used to determine susceptibility to scarlet fever.2 It was also shown that the toxicity of the filtrate is neutralized by addition of convalescent scarlet fever serum; and that persons who show positive skin tests before passive immunization with convalescent serum give negative tests afterward.These results suggest that we are dealing with a toxic substance specific for scarlet fever, and that it might be used in the production of active immunity. After a number of preliminary tests to determine what amounts of the filtrate, injected intramuscularly, might be expected to give a reaction, the following attempts at immunization were made:Experiment 1.
—A healthy girl, aged
Endotoxin (lipopolysaccharide; LPS) and superantigens (exotoxins) have been identified as potent inducers of lethal shock. While endotoxin primarily interacts with CD 14 receptors on macrophages, superantigens like the staphylococcal enterotoxin B (SEB) preferentially activate T cells. Both cell types are triggered to release pro-inflammatory cytokines that in turn induce lethal shock. We analyzed whether endotoxin and superantigen interact during the induction phase of lethal shock. We report that LPS and SEB operate synergistically. Lethal doses of both inducers were reduced 100-fold when given in combination. The induced serum levels of tumor necrosis factor, interleukin-6, and interferon-γ (IFN-γ) were elevated and remained high for a prolonged period. Moreover, synergistic action of LPS and SEB induced lethal toxic shock even without presensitization of mice with D-galactosamine (D-GalN). Opposed to D-GalN-pretreated mice, mice injected with LPS and SEB showed less liver damage, but rather apoptosis of epithelial cells in the bowel. Cyclosporin A and treatment with anti-IFN-γ monoclonal antibody blocked the synergistic action of LPS and SEB, indicating that T cell-derived IFN-γ is the mediator of the observed synergism. Concomitant injection of LPS and SEB had no influence on SEB-induced T cell deletion and anergy induction. Since Gram-positive and Gram-negative bacteria can be recovered from septic blood samples, the synergistic action of endotoxin and superantigens might be relevant during lethal septicemia.