Toll-like receptors 2 and 7 mediate coagulation activation and coagulopathy in murine sepsis

Association of TLR8 Variants in Sex-Based Clinical Differences in Patients with COVID-19

The host immune response might confer differential vulnerability to SARS-CoV-2 infection. The Toll-like receptor 8 (TLR8), could participated for severe COVID-19 outcomes. To investigated the relationship of TLR8 rs3764879-C/G, rs3764880-A/G, and rs3761624-A/G with COVID-19 outcomes and with biochemical parameters. A cross-sectional study of 830 laboratory-confirmed COVID-19 patients was performed, and classified into mild, severe, critical, and deceased outcomes. The TLR8 rs3764879-C/G, rs3764880-A/G, and rs3761624-A/G polymorphisms were genotyped. A logistic regression analysis was performed to determinate the association with COVID-19. A stratified analysis was by alleles was done with clinical and metabolic markets. In all outcomes, men presented the highest ferritin levels compared to women (P < 0.001). LDH levels were significantly different between sex in mild (P = 0.003), severe (P < 0.001) and deceased (P = 0.01) COVID-19 outcomes. The GGG haplotype showed an Odds Ratio of 1.55 (Interval Confidence 95% 1.05-2.32; P = 0.03) in men. Among patients with severe outcome, we observed that the carriers of the GGG haplotype had lower Ferritin, C-reactive protein and LDH levels than the CAA carriers (P < 0.01). After further stratified by sex, these associations were also seen in the male patients, except for D-dimer. Interestingly, among men patients, we could observe associations between TLR8 haplotypes and Ferritin (P < 0.001), D-dimer (P = 0.04), C-reactive protein, and Lactate dehydrogenase in mild (P = 0.04) group. Our results suggest that even though TLR8 haplotypes show a significant association with COVID-19 outcomes, they are associated with clinical markers in COVID-19 severity.

Effect of ethanol exposure on innate immune response in sepsis

Alcohol use disorder, reported by 1 in 8 critically ill patients, is a risk factor for death in sepsis patients. Sepsis, the leading cause of death, kills over 270,000 patients in the United States alone and remains without targeted therapy. Immune response in sepsis transitions from an early hyperinflammation to persistent inflammation and immunosuppression and multiple organ dysfunction during late sepsis. Innate immunity is the first line of defense against pathogen invasion. Ethanol exposure is known to impair innate and adaptive immune response and bacterial clearance in sepsis patients. Specifically, ethanol exposure is known to modulate every aspect of innate immune response with and without sepsis. Multiple molecular mechanisms are implicated in causing dysregulated immune response in ethanol exposure with sepsis, but targeted treatments have remained elusive. In this article, we outline the effects of ethanol exposure on various innate immune cell types in general and during sepsis.

Toll-like receptors in health and disease

Toll-like receptors (TLRs) are inflammatory triggers and belong to a family of pattern recognition receptors (PRRs) that are central to the regulation of host protective adaptive immune responses. Activation of TLRs in innate immune myeloid cells directs lymphocytes to produce the most appropriate effector responses to eliminate infection and maintain homeostasis of the body's internal environment. Inappropriate TLR stimulation can lead to the development of general autoimmune diseases as well as chronic and acute inflammation, and even cancer. Therefore, TLRs are expected to be targets for therapeutic treatment of inflammation-related diseases, autoimmune diseases, microbial infections, and human cancers. This review summarizes the recent discoveries in the molecular and structural biology of TLRs. The role of different TLR signaling pathways in inflammatory diseases, autoimmune diseases such as diabetes, cardiovascular diseases, respiratory diseases, digestive diseases, and even cancers (oral, gastric, breast, colorectal) is highlighted and summarizes new drugs and related clinical treatments in clinical trials, providing an overview of the potential and prospects of TLRs for the treatment of TLR-related diseases.

Sepsis-Induced Coagulopathy: A Comprehensive Narrative Review of Pathophysiology, Clinical Presentation, Diagnosis, and Management Strategies

Physiological hemostasis is a balance between pro- and anticoagulant pathways, and in sepsis, this equilibrium is disturbed, resulting in systemic thrombin generation, impaired anticoagulant activity, and suppression of fibrinolysis, a condition termed sepsis-induced coagulopathy (SIC). SIC is a common complication, being present in 24% of patients with sepsis and 66% of patients with septic shock, and is often associated with poor clinical outcomes and high mortality. 1 , 2 Recent preclinical and clinical studies have generated new insights into the molecular pathogenesis of SIC. In this article, we analyze the complex pathophysiology of SIC with a focus on the role of procoagulant innate immune signaling in hemostatic activation--tissue factor production, thrombin generation, endotheliopathy, and impaired antithrombotic functions. We also review clinical presentations of SIC, the diagnostic scoring system and laboratory tests, the current standard of care, and clinical trials evaluating the efficacies of anticoagulant therapies.

An Update on Toll-like Receptor 2, Its Function and Dimerization in Pro- and Anti-Inflammatory Processes

While a certain level of inflammation is critical for humans to survive infection and injury, a prolonged inflammatory response can have fatal consequences. Pattern recognition Toll-like receptors (TLRs) are key players in the initiation of an inflammatory process. TLR2 is one of the most studied pattern recognition receptors (PRRs) and is known to form heterodimers with either TLR1, TLR4, TLR6, and TLR10, allowing it to recognize a wide range of pathogens. Although a large number of studies have been conducted over the past decades, there are still many unanswered questions regarding TLR2 mechanisms in health and disease. In this review, we provide an up-to-date overview of TLR2, including its homo- and heterodimers. Furthermore, we will discuss the pro- and anti-inflammatory properties of TLR2 and recent findings in prominent TLR2-associated infectious and neurodegenerative diseases.

Toll-like Receptors as Pro-Thrombotic Drivers in Viral Infections: A Narrative Review

Toll-like receptors (TLRs) have a critical role in the pathogenesis and disease course of viral infections. The induced pro-inflammatory responses result in the disturbance of the endovascular surface layer and impair vascular homeostasis. The injury of the vessel wall further promotes pro-thrombotic and pro-coagulatory processes, eventually leading to micro-vessel plugging and tissue necrosis. Moreover, TLRs have a direct role in the sensing of viruses and platelet activation. TLR-mediated upregulation of von Willebrand factor release and neutrophil, as well as macrophage extra-cellular trap formation, further contribute to (micro-) thrombotic processes during inflammation. The following review focuses on TLR signaling pathways of TLRs expressed in humans provoking pro-thrombotic responses, which determine patient outcome during viral infections, especially in those with cardiovascular diseases.

Extracellular RNA Sensing Mediates Inflammation and Organ Injury in a Murine Model of Polytrauma

Severe traumatic injury leads to marked systemic inflammation and multiorgan injury. Endogenous drivers such as extracellular nucleic acid may play a role in mediating innate immune response and the downstream pathogenesis. Here, we explored the role of plasma extracellular RNA (exRNA) and its sensing mechanism in inflammation and organ injury in a murine model of polytrauma. We found that severe polytrauma-bone fracture, muscle crush injury, and bowel ischemia-induced a marked increase in plasma exRNA, systemic inflammation, and multiorgan injury in mice. Plasma RNA profiling with RNA sequencing in mice and humans revealed a dominant presence of miRNAs and marked differential expression of numerous miRNAs after severe trauma. Plasma exRNA isolated from trauma mice induced a dose-dependent cytokine production in macrophages, which was almost abolished in TLR7-deficient cells but unchanged in TLR3-deficient cells. Moreover, RNase or specific miRNA inhibitors against the selected proinflammatory miRNAs (i.e., miR-7a-5p, miR-142, let-7j, miR-802, and miR-146a-5p) abolished or attenuated trauma plasma exRNA-induced cytokine production, respectively. Bioinformatic analyses of a group of miRNAs based on cytokine readouts revealed that high uridine abundance (>40%) is a reliable predictor in miRNA mimic-induced cytokine and complement production. Finally, compared with the wild-type, TLR7-knockout mice had attenuated plasma cytokine storm and reduced lung and hepatic injury after polytrauma. These data suggest that endogenous plasma exRNA of severely injured mice and ex-miRNAs with high uridine abundance prove to be highly proinflammatory. TLR7 sensing of plasma exRNA and ex-miRNAs activates innate immune responses and plays a role in inflammation and organ injury after trauma.

Recent Advances in Monoclonal Antibody-Based Approaches in the Management of Bacterial Sepsis

Sepsis is a life-threatening condition characterized by an uncontrolled inflammatory response to an infectious agent and its antigens. Immune cell activation against the antigens causes severe distress that mediates a strong inflammatory response in vital organs. Sepsis is responsible for a high rate of morbidity and mortality in immunosuppressed patients. Monoclonal antibody (mAb)-based therapeutic strategies are now being explored as a viable therapy option for severe sepsis and septic shock. Monoclonal antibodies may provide benefits through two major strategies: (a) monoclonal antibodies targeting the pathogen and its components, and (b) mAbs targeting inflammatory signaling may directly suppress the production of inflammatory mediators. The major focus of mAb therapies has been bacterial endotoxin (lipopolysaccharide), although other surface antigens are also being investigated for mAb therapy. Several promising candidates for mAbs are undergoing clinical trials at present. Despite several failures and the investigation of novel targets, mAb therapy provides a glimmer of hope for the treatment of severe bacterial sepsis and septic shock. In this review, mAb candidates, their efficacy against controlling infection, with special emphasis on potential roadblocks, and prospects are discussed.

EMERGING ROLE OF EXTRACELLULAR RNA IN INNATE IMMUNITY, SEPSIS, AND TRAUMA

ABSTRACT

Sepsis and trauma remain the leading causes of morbidity and mortality. Our understanding of the molecular pathogenesis in the development of multiple organ dysfunction in sepsis and trauma has evolved as more focus is on secondary injury from innate immunity, inflammation, and the potential role of endogenous danger molecules. Studies of the past several decades have generated evidence for extracellular RNAs (exRNAs) as biologically active mediators in health and disease. Here, we review studies on plasma exRNA profiling in mice and humans with sepsis and trauma, the role and mode of action by exRNAs, such as ex-micro(mi)RNAs, in host innate immune response, and their potential implications in various organ injury during sepsis and trauma.

Innate immune TLR7 signaling mediates platelet activation and platelet-leukocyte aggregate formation in murine bacterial sepsis

Thrombocytopenia is a common complication in sepsis and is associated with higher mortality. Activated platelets express CD62P, which facilitates platelet-leukocyte aggregate (PLA) formation and contributes to thrombocytopenia in sepsis. We have reported that thrombocytopenia in murine sepsis is partly attributable to TLR7 signaling, but the underlying mechanism is unclear. In the current study, we tested the hypothesis that TLR7 mediates platelet activation and PLA formation during sepsis. In vitro, whole blood from WT mice treated with loxoribine, a TLR7 agonist, exhibited a dose-dependent increase in activated platelets compared to the control (PBS with 0.05% DMSO) or loxoribine-treated TLR7^-/- whole blood. In a murine model of sepsis, there was a significant increase in platelet activation and PLA formation 24 hours after cecal ligation and puncture (CLP) as evidenced by double positive expression of CD41⁺/CD62P⁺ and CD45⁺/CD62P⁺, respectively. The sepsis-induced PLA formation was significantly attenuated in TLR7^-/- mice. Finally, in ex-vivo experiments, plasma isolated from septic mice induced WT platelet activation, but such effect was significantly attenuated in platelets deficient of TLR7. These findings demonstrate a pivotal role of TLR7 signaling in platelet activation and PLA formation during bacterial sepsis.

TLR7 Mediates Acute Respiratory Distress Syndrome in Sepsis by Sensing Extracellular miR-146a

TLR7 (Toll-like receptor 7), the sensor for single-stranded RNA, contributes to systemic inflammation and mortality in murine polymicrobial sepsis. Recent studies show that extracellular miR-146a-5p serves as a TLR7 ligand and plays an important role in regulating host innate immunity. However, the role of miR-146a-5p and TLR7 signaling in pulmonary inflammation, endothelial activation, and sepsis-associated acute respiratory distress syndrome remains unclear. Here, we show that intratracheal administration of exogenous miR-146a-5p in mice evokes lung inflammation, activates endothelium, and increases endothelial permeability via TLR7-dependent mechanisms. TLR7 deficiency attenuates pulmonary barrier dysfunction and reduces lung inflammatory response in a murine sepsis model. Moreover, the impact of miR-146a-5p-TLR7 signaling on endothelial activation appears to be a secondary effect because TLR7 is undetectable in the human pulmonary artery and microvascular endothelial cells (ECs), which show no response to direct miR-146a-5p treatment in vitro. Both conditioned media of miR-146a-5p-treated macrophages (Mϕ) and septic sera of wild-type mice induce a marked EC barrier disruption in vitro, whereas Mϕ conditioned media or septic sera of TLR7-/- mice do not exhibit such effect. Cytokine array and pathway enrichment analysis of the Mϕ conditioned media and septic sera identify TNFα (tumor necrosis factor α) as the main downstream effector of miR-146a-5p-TLR7 signaling responsible for the EC barrier dysfunction, which is further supported by neutralizing anti-TNFα antibody intervention. Together, these data demonstrate that TLR7 activation elicits pulmonary inflammation and endothelial barrier disruption by sensing extracellular miR-146a-5p and contributes to sepsis-associated acute respiratory distress syndrome.

Disseminated intravascular coagulation and its immune mechanisms

Disseminated intravascular coagulation (DIC) is a syndrome triggered by infectious and noninfectious pathologies characterized by excessive generation of thrombin within the vasculature and widespread proteolytic conversion of fibrinogen. Despite diverse clinical manifestations ranging from thrombo-occlusive damage to bleeding diathesis, DIC etiology commonly involves excessive activation of blood coagulation and overlapping dysregulation of anticoagulants and fibrinolysis. Initiation of blood coagulation follows intravascular expression of tissue factor or activation of the contact pathway in response to pathogen-associated or host-derived, damage-associated molecular patterns. The process is further amplified through inflammatory and immunothrombotic mechanisms. Consumption of anticoagulants and disruption of endothelial homeostasis lower the regulatory control and disseminate microvascular thrombosis. Clinical DIC development in patients is associated with worsening morbidities and increased mortality, regardless of the underlying pathology; therefore, timely recognition of DIC is critical for reducing the pathologic burden. Due to the diversity of triggers and pathogenic mechanisms leading to DIC, diagnosis is based on algorithms that quantify hemostatic imbalance, thrombocytopenia, and fibrinogen conversion. Because current diagnosis primarily assesses overt consumptive coagulopathies, there is a critical need for better recognition of nonovert DIC and/or pre-DIC states. Therapeutic strategies for patients with DIC involve resolution of the eliciting triggers and supportive care for the hemostatic imbalance. Despite medical care, mortality in patients with DIC remains high, and new strategies, tailored to the underlying pathologic mechanisms, are needed.

Brain innate immune response via miRNA-TLR7 sensing in polymicrobial sepsis

Sepsis-associated encephalopathy (SAE) occurs in sepsis survivors and is associated with breakdown of the blood-brain barrier (BBB), brain inflammation, and neurological dysfunction. We have previously identified a group of extracellular microRNAs (ex-miRNAs), such as miR-146a-5p, that were upregulated in the plasma of septic mice and human, and capable of inducing potent pro-inflammatory cytokines and complements. Here, we established a clinically relevant mouse model of SAE and investigated the role of extracellular miRNAs and their sensor Toll-like receptor 7 (TLR7) in brain inflammation and neurological dysfunction. We observed BBB disruption and a profound neuroinflammatory responses in the brain for up to 14 days post-sepsis; these included increased pro-inflammatory cytokines production, microglial expansion, and peripheral leukocyte accumulation in the CNS. In a battery of neurobehavioral tests, septic mice displayed impairment of motor coordination and neurological function. Sepsis significantly increased plasma RNA and miRNA levels for up to 7 days, such as miR-146a-5p. Exogenously added miR-146a-5p induces innate immune responses in both cultured microglia/astrocytes and the intact brain via a TLR7-dependent manner. Moreover, mice genetically deficient of miR-146a showed reduced accumulation of monocytes and neutrophils in the brain compared to WT after sepsis. Finally, ablation of TLR7 in the TLR7^-/- mice preserved BBB integrity, reduced microglial expansion and leukocyte accumulation, and attenuated GSK3β signaling in the brain, but did not improve neurobehavioral recovery following sepsis. Taken together, these data establish an important role of extracellular miRNA and TLR7 sensing in sepsis-induced brain inflammation.

Role of extracellular microRNA-146a-5p in host innate immunity and bacterial sepsis

Extracellular miRNAs (ex-miRNAs) mediate intercellular communication and play a role in diverse physiological and pathological processes. Using small RNA sequencing, we identify that miRNAs are the most abundant RNA species in the plasma and differentially expressed in murine and human sepsis, such as miR-146a-5p. Exogenous miR-146a-5p, but not its duplex precursor, induces a strong immunostimulatory response through a newly identified UU-containing motif and TLR7 activation, and an immunotolerance by rapid IRAK-1 protein degradation via TLR7→MyD88 signaling and proteasome activation, whereas its duplex precursor acts by targeting 3' UTR of Irak-1 gene via Ago2 binding. miR-146a knockout in mice offers protection against sepsis with attenuated interleukin-6 (IL-6) storm and organ injury, improved cardiac function, and better survival. In septic patients, the plasma miR-146a-5p concentrations are closely associated with the two sepsis outcome predictors, blood lactate and coagulopathy. These data demonstrate the importance of extracellular miR-146a-5p in innate immune regulation and sepsis pathogenesis.

Targeting Toll-Like Receptors in Sepsis: From Bench to Clinical Trials

Significance: Sepsis is a critical clinical syndrome with life-threatening organ dysfunction induced by a dysregulated host response to infection. Despite decades of intensive research, sepsis remains a leading cause of in-hospital mortality with few specific treatments. Recent Advances: Toll-like receptors (TLRs) are a part of the innate immune system and play an important role in host defense against invading pathogens such as bacteria, virus, and fungi. Using a combination of genetically modified animal models and pharmacological agents, numerous preclinical studies during the past two decades have demonstrated that dysregulated TLR signaling may contribute to sepsis pathogenesis. However, many clinical trials targeting inflammation and innate immunity such as TLR4 have yielded mixed results. Critical Issues: Here we review various TLRs and the specific molecules these TLRs sense-both the pathogen-associated and host-derived stress molecules, and their converging signaling pathways. We critically analyze preclinical investigations into the role of TLRs in animal sepsis, the complexity of targeting TLRs for sepsis intervention, and the disappointing clinical trials of the TLR4 antagonist eritoran. Future Directions: Future sepsis treatments will depend on better understanding the complex biological mechanisms of sepsis pathogenesis, the high heterogeneity of septic humans as defined by clinical presentations and unique immunological biomarkers, and improved stratifications for targeted interventions.

Brain-derived extracellular vesicles mediated coagulopathy, inflammation and apoptosis after sepsis

INTRODUCTION

The activation of coagulation, inflammation and other pathways is the basic response of the host to infection in sepsis, but this response also causes damage to the host. Brain-derived extracellular vesicles (BDEVs) have been reported to cause a hypercoagulable state that can rapidly develop into consumptive coagulopathy, which is consistent with the pathophysiological process of sepsis-induced coagulopathy. However, the role of BDEVs in sepsis-induced coagulopathy remains unclear.

MATERIALS AND METHODS

Male Sprague-Dawley (SD) rats were used for sepsis modeling using cecal ligation puncture (CLP). Flow cytometry was used to measure the levels of circulating BDEVs. Enzyme-linked immunosorbent assay (ELISA) was used to measure the serum levels of plasminogen activator inhibitor type 1 (PAI-1), thrombin-antithrombin (TAT), D-dimer, fibrinogen(Fib), tumor necrosis factor-alpha (TNF-α), interleukin (IL)-1β and IL-6. Nanoparticle tracking analysis (NTA) and Transmission electron microscopy (TEM) were used to identify BDEVs. Western blot (WB) was used to determine the expression of glial fibrillary acidic protein (GFAP), neuron-specific enolase (NSE), bax, bcl-2 and cleaved caspase-3. Hematoxylin-eosin (HE) and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) staining were performed to detect tissue injury. Survival was monitored over the course of 168 h.

RESULTS

We found that a large number of BDEVs were released into the circulating blood in septic rats. Moreover, we observed that BDEVs injection activated the systemic coagulation reaction and induced lung, liver and kidney inflammation and apoptosis(P < .05). Compared with BDEVs from sham-operated rats, BDEVs from septic rats exacerbated this process(P < .05).

CONCLUSIONS

This finding suggests that inhibiting BDEVs may yield therapeutic benefits in the treatment of sepsis-induced coagulopathy.

Platelet Innate Immune Receptors and TLRs: A Double-Edged Sword

Platelets are hematopoietic cells whose main function has for a long time been considered to be the maintenance of vascular integrity. They have an essential role in the hemostatic response, but they also have functional capabilities that go far beyond it. This review will provide an overview of platelet functions. Indeed, stress signals may induce platelet apoptosis through proapoptotis or hemostasis receptors, necrosis, and even autophagy. Platelets also interact with immune cells and modulate immune responses in terms of activation, maturation, recruitment and cytokine secretion. This review will also show that platelets, thanks to their wide range of innate immune receptors, and in particular toll-like receptors, and can be considered sentinels actively participating in the immuno-surveillance of the body. We will discuss the diversity of platelet responses following the engagement of these receptors as well as the signaling pathways involved. Finally, we will show that while platelets contribute significantly, via their TLRs, to immune response and inflammation, these receptors also participate in the pathophysiological processes associated with various pathogens and diseases, including cancer and atherosclerosis.

Toll-Like Receptor Signaling Pathways: Novel Therapeutic Targets for Cerebrovascular Disorders

Toll-like receptors (TLRs), a class of pattern recognition proteins, play an integral role in the modulation of systemic inflammatory responses. Cerebrovascular diseases (CVDs) are a group of pathological conditions that temporarily or permanently affect the brain tissue mostly via the decrease of oxygen and glucose supply. TLRs have a critical role in the activation of inflammatory cascades following hypoxic-ischemic events and subsequently contribute to neuroprotective or detrimental effects of CVD-induced neuroinflammation. The TLR signaling pathway and downstream cascades trigger immune responses via the production and release of various inflammatory mediators. The present review describes the modulatory role of the TLR signaling pathway in the inflammatory responses developed following various CVDs and discusses the potential benefits of the modulation of different TLRs in the improvement of functional outcomes after brain ischemia.

Innate Receptor Activation Patterns Involving TLR and NLR Synergisms in COVID-19, ALI/ARDS and Sepsis Cytokine Storms: A Review and Model Making Novel Predictions and Therapeutic Suggestions

Severe COVID-19 is characterized by a “cytokine storm”, the mechanism of which is not yet understood. I propose that cytokine storms result from synergistic interactions among Toll-like receptors (TLR) and nucleotide-binding oligomerization domain-like receptors (NLR) due to combined infections of SARS-CoV-2 with other microbes, mainly bacterial and fungal. This proposition is based on eight linked types of evidence and their logical connections. (1) Severe cases of COVID-19 differ from healthy controls and mild COVID-19 patients in exhibiting increased TLR4, TLR7, TLR9 and NLRP3 activity. (2) SARS-CoV-2 and related coronaviruses activate TLR3, TLR7, RIG1 and NLRP3. (3) SARS-CoV-2 cannot, therefore, account for the innate receptor activation pattern (IRAP) found in severe COVID-19 patients. (4) Severe COVID-19 also differs from its mild form in being characterized by bacterial and fungal infections. (5) Respiratory bacterial and fungal infections activate TLR2, TLR4, TLR9 and NLRP3. (6) A combination of SARS-CoV-2 with bacterial/fungal coinfections accounts for the IRAP found in severe COVID-19 and why it differs from mild cases. (7) Notably, TLR7 (viral) and TLR4 (bacterial/fungal) synergize, TLR9 and TLR4 (both bacterial/fungal) synergize and TLR2 and TLR4 (both bacterial/fungal) synergize with NLRP3 (viral and bacterial). (8) Thus, a SARS-CoV-2-bacterium/fungus coinfection produces synergistic innate activation, resulting in the hyperinflammation characteristic of a cytokine storm. Unique clinical, experimental and therapeutic predictions (such as why melatonin is effective in treating COVID-19) are discussed, and broader implications are outlined for understanding why other syndromes such as acute lung injury, acute respiratory distress syndrome and sepsis display varied cytokine storm symptoms.

The Microbial Flora in an Experimental Polymicrobial Abdominal Sepsis Model Probed by 16S rRNA Sequencing

BACKGROUND

Cecal ligation and puncture (CLP) surgery is a widely used preclinical model to induce and study sepsis because it is considered to recapitulate the course of human sepsis the most. This model is highly dependent on the polymicrobial gut flora and represents polymicrobial abdominal sepsis. While the majority of studies using CLP model have focused on the delineation of host immune responses, a limited number of reports have described the composition of microbial strains in this model, although microbial composition can significantly affect the outcome of sepsis in general.

METHODS

CLP surgery was performed in mice on C57BL6/J from the Jackson laboratory. We examined the composition of microbes at the peritoneal cavity using 16S rRNA sequencing after CLP surgery at 12 and 24 hours. Baseline cecal microbial flora was also analyzed.

RESULTS

The bacteria strains from the initial cecum flora consisted of mixed aerobic and anaerobic flora. There was a significant change of bacteria flora from the peritoneal cavity between 12 and 24 hours following CLP surgery. Particularly a significantly increased proportion of anaerobic microbes were noted at 24 hours after CLP surgery. We also tested bacterial composition of cecal flora of mice on the same background from the same vendor 6 months later. Baseline cecal microbial flora was different from earlier mice, showing that baseline cecal flora could be different depending on the batch of mice.

CONCLUSION

There was a dynamical chance of peritoneal microbes during CLP sepsis. Potential difference in baseline cecal flora should be kept in mind upon CLP surgery even when using mice from the same vendor.

How Fungal Glycans Modulate Platelet Activation via Toll-Like Receptors Contributing to the Escape of Candida albicans from the Immune Response

Platelets are essential for vascular repair and for the maintenance of blood homeostasis. They contribute to the immune defence of the host against many infections caused by bacteria, viruses and fungi. Following infection, platelet function is modified, and these cells form aggregates with microorganisms leading, to a decrease in the level of circulating platelets. During candidaemia, mannans, β-glucans and chitin, exposed on the cell wall of Candida albicans, an opportunistic pathogenic yeast of humans, play an important role in modulation of the host response. These fungal polysaccharides are released into the circulation during infection and their detection allows the early diagnosis of invasive fungal infections. However, their role in the modulation of the immune response and, in particular, that of platelets, is not well understood. The structure and solubility of glycans play an important role in the orientation of the immune response of the host. This short review focuses on the effect of fungal β-glucans and chitin on platelet activation and how these glycans modulate platelet activity via Toll-like receptors, contributing to the escape of C. albicans from the immune response.