Inflammatory Sepsis Research Articles

M1 Macrophages Increase Endothelial Permeability and Enhance p38 Phosphorylation via PPAR-γ/CXCL13-CXCR5 in Sepsis

Purpose: Vascular endothelial hyperpermeability and barrier disruption are involved in the initiation and development of sepsis. M1 macrophages promote inflammation in sepsis by releasing pro-inflammatory cytokines and chemokines. This study was designed to investigate the functional relationships between M1 macrophages and human umbilical vein endothelial cells (HUVECs), as well as the underlying molecular mechanisms. Methods: HUVECs were co-cultured with THP-1-derived M1 macrophages pretreated with or without rosiglitazone (RSG), a peroxisome proliferator-activated receptor (PPAR)-γ agonist. C-X-C chemokine receptor type (CXCR)5 was knocked down by short hairpin RNA lentivirus. Cecal ligation and puncture were used to induce sepsis in a mouse model. Endothelial permeability was evaluated using transendothelial electrical resistance and fluorescein isothiocyanate (FITC)-dextran assays. Results: Chemokine ligand (CXCL)13 was upregulated in M1 macrophages than M0 macrophages, as well as in the culture medium. In HUVECs co-cultured with M1 macrophages, transendothelial electrical resistance decreased, FITC-dextran flux increased, p38 phosphorylation was strengthened, and the expression of tight junction proteins (zonula occludens protein-1, occludin, and claudin-4) decreased. CXCR5 RNA interference or RSG pretreatment partially reversed these effects. A luciferase reporter assay revealed that CXCL13 was a direct target of PPAR-γ. RSG treatment decreased serum levels of creatinine, blood urea nitrogen, CXCL13, tumor necrosis factor-α, and interleukin-6, downregulated CXCL13 in peritoneal macrophages, and enhanced the survival rate of sepsis mice. Conclusion: M1 macrophages induced endothelial hyperpermeability and promoted p38 phosphorylation in sepsis by inhibiting PPAR-γ to increase CXCL13 production. PPAR-γ/CXCL13-CXCR5 signaling could be a promising novel therapeutic target for sepsis.

Active Release of eCIRP via Gasdermin D Channels to Induce Inflammation in Sepsis.

Extracellular cold-inducible RNA binding protein (eCIRP) is an inflammatory mediator that causes inflammation and tissue injury in sepsis. Gasdermin D (GSDMD) is a protein that, when cleaved, forms pores in the cell membrane, releasing intracellular contents into the extracellular milieu to exacerbate inflammation. We hypothesize that eCIRP is released actively from viable macrophages via GSDMD pores. We found that LPS induced eCIRP secretion from macrophages into the extracellular space. LPS significantly increased the expression of caspase-11 and cleavage of the GSDMD, as evidenced by increased N-terminal GSDMD expression in RAW 264.7 cells and mouse primary peritoneal macrophages. GSDMD inhibitor disulfiram decreased eCIRP release in vitro. Treatment with glycine to prevent pyroptosis-induced cell lysis did not significantly decrease eCIRP release from LPS-treated macrophages, indicating that eCIRP was actively released and was independent of pyroptosis. Downregulation of GSDMD gene expression by siRNA transfection suppressed eCIRP release in vitro after LPS stimulation. Moreover, GSDMD-/- peritoneal macrophages and mice had decreased levels of eCIRP in the culture supernatants and in blood treated with LPS in vitro and in vivo, respectively. GSDMD inhibitor disulfiram inhibited serum levels of eCIRP in endotoxemia and cecal ligation and puncture-induced sepsis. We conclude that eCIRP release from living macrophages is mediated through GSDMD pores, suggesting that targeting GSDMD could be a novel and potential therapeutic approach to inhibit eCIRP-mediated inflammation in sepsis.

Ketone Therapy Reduces Systemic and Organ Inflammation in Sepsis

IntroductionSepsis is the body's reaction to an infection that often causes lasting multi‐organ injury due to a dysregulated inflammatory response. Currently, there are no effective treatments to reduce inflammation during sepsis and assist in preventing the lasting inflammation‐mediated damage and thus, sepsis accounts for approximately 20% of all global causes of death. In addition, many patients who recover from sepsis have permanent damage to many organ systems which makes them more susceptible to future injury that likely affects them more severely. Thus, therapeutic strategies to reduce the inflammatory response in sepsis are needed to save lives and improve the outcomes and quality of life of those who survive sepsis. Herein, we tested the efficacy of a ketone therapy that increases circulating ketones via ketone ester supplementation. Ketones are small molecules that are normally produced by the liver and are elevated during carbohydrate‐deprived states, such as fasting or exercise. While ketones are classically known to be a metabolic source of energy, they also have non‐metabolic effects, such as inhibiting inflammation, which can be of therapeutic importance. We hypothesized that ketones have potent anti‐inflammatory effects in a mouse model of lipopolysaccharide (LPS)‐induced sepsis and that ketones can be used to mitigate the inflammation‐mediated organ damage.ObjectiveTo determine if ketone supplementation can effectively reduce inflammation and organ dysfunction/damage in a model of LPS‐induced sepsis.Methods8‐week‐old mice orally received either vehicle or a clinically tested ketone ester (KE) for 3 days. On day 3, mice were injected with saline or LPS to induce systemic inflammation and organ damage. 24 hours post‐injection, cardiac function was assessed and then mice were euthanized to assess systemic and organ inflammation from the 3 groups (control, LPS, LPS+KE).ResultsLPS‐treated mice had higher blood ketones compared to controls, suggesting that ketones may be important as an innate defense mechanism, and this response was further augmented in KE‐treated septic mice. While LPS‐treated mice had an induction of systemic pro‐inflammatory cytokines (e.g., IL‐1β, IL‐6, interferon‐γ) these cytokines were significantly lower in KE‐treated septic mice. Similarly, LPS induced numerous inflammatory markers in the heart, kidney, and liver, a large majority of which were reduced in the KE‐treated septic mice. LPS‐induced cardiac dysfunction and renal fibrosis was also significantly lower in KE‐treated septic mice. Finally, there was either no change or a reduction of ketolytic enzymes in various organs, suggesting that these protective and anti‐inflammatory effects do not depend on ketone metabolism for energy production.ConclusionTogether, these data are the first to show that ketone therapy may be a novel approach to reducing systemic and organ inflammation and dysfunction, and subsequent organ damage in a model of LPS‐induced sepsis.

LncRNA GAS5 relates to Th17 cells and serves as a potential biomarker for sepsis inflammation, organ dysfunctions and mortality risk.

BackgroundLong noncoding RNA GAS5 (lnc‐GAS5) is able to regulate macrophage M1 polarization and Th17 cell differentiation, also engaged in sepsis‐induced inflammation and organ injury. This study aimed to further evaluate its linkage with Th1 cells and Th17 cells, as well as its clinical value in sepsis management.MethodsAbout 101 sepsis patients were enrolled followed by peripheral blood mononuclear cell (PBMC) and serum samples collection. PBMC lnc‐GAS5 was detected by RT‐qPCR; Th1 cells and Th17 cells in PBMC CD4+ T cells were detected by flow cytometry; serum IFN‐γ and IL‐17A were detected by ELISA. Besides, PBMC lnc‐GAS5 was also detected in 50 health controls (HCs).ResultsLnc‐GAS5 was reduced in sepsis patients than in HCs (p < 0.001), which also well‐distinguished sepsis patients from HCs with AUC 0.860. Lnc‐GAS5 did not relate to Th1 cells (p = 0.059) or IFN‐γ (p = 0.192); while negatively linked with Th17 cells (p = 0.002) and IL‐17A (p = 0.019) in sepsis patients. Interestingly, lnc‐GAS5 negatively correlated with SOFA score (p = 0.001), SOFA‐Respiratory system score (p = 0.001), SOFA‐Coagulation score (p = 0.015), and SOFA‐Renal system score (p = 0.026), but not SOFA‐Liver score (p = 0.080), SOFA‐Cardiovascular system score (p = 0.207) or SOFA‐Nervous system score (p = 0.182) in sepsis patients. Furthermore, lnc‐GAS5 was negatively related to CRP (p = 0.002) and APACHE II score (p = 0.004) in sepsis patients. Finally, lnc‐GAS5 was decreased in dead sepsis patients compared to survivors (p = 0.007), which also distinguished sepsis deaths from survivors with AUC 0.713.ConclusionLnc‐GAS5 relates to Th17 cells and serves as a potential biomarker for sepsis severity and mortality risk.

MicroRNA-23a-3p targeting of HMGB1 inhibits LPS-induced inflammation in murine macrophages in vitro.

Inflammatory cytokines, including high mobility group box 1 (HMGB1), play a key role in sepsis via various mechanisms, some of which remain unknown. Sepsis is a common cause of death in patients admitted to the intensive care unit. MicroRNAs (miRs) serve an important role in the inflammatory response. The present study aimed to investigate the role of miR-23a-3p in macrophage inflammation and the targeted regulation of HMGB1 expression. The murine macrophage cell line RAW264.7 was subjected to lipopolysaccharide (LPS) treatment to mimic the inflammation involved in sepsis in vitro. Reverse transcription-quantitative PCR was performed to measure miR-23a-3p expression and mRNA expression. Protein levels were determined using ELISA and western blotting. The target binding relationship between miR-23a-3p and the HMGB1 3'untranslated region was predicted and validated with a dual luciferase reporter assay. HMGB1 expression was increased and miR-23a-3p expression significantly reduced in patients with sepsis and in LPS-treated RAW264.7 cells in comparison with controls. Overexpression of miR-23a-3p reduced interleukin (IL)-6 and tumor necrosis factor (TNF)-α expression in RAW264.7 cells under LPS stimulation, while silencing of miR-23a-3p elevated the expression of IL-6 and TNF-α in comparison with controls. The inhibitory effect of miR-23a-3p on LPS-induced inflammation could be abolished by HMGB1 upregulation in RAW264.7 cells. HMGB1 was targeted by miR-23a-3p. miR-23a-3p is expressed at reduced levels during inflammation in sepsis, and overexpression of miR-23a-3p inhibits LPS-induced inflammation in murine macrophages in vitro by directly downregulating HMGB1. The results of the present study provided a novel insight into the molecular mechanism underlying HMGB1 expression at the post-transcriptional level in sepsis.

C-Abl kinase regulates neutrophil extracellular trap formation and lung injury in abdominal sepsis

AbstractSepsis is associated with exaggerated neutrophil responses although mechanisms remain elusive. The aim of this study was to investigate the role of c-Abelson (c-Abl) kinase in neutrophil extracellular trap (NET) formation and inflammation in septic lung injury. Abdominal sepsis was induced by cecal ligation and puncture (CLP). NETs were detected by electron microscopy in the lung and by confocal microscopy in vitro. Plasma levels of DNA-histone complexes, interleukin-6 (IL-6) and CXC chemokines were quantified. CLP-induced enhanced phosphorylation of c-Abl kinase in circulating neutrophils. Administration of the c-Abl kinase inhibitor GZD824 not only abolished activation of c-Abl kinase in neutrophils but also reduced NET formation in the lung and plasma levels of DNA-histone complexes in CLP mice. Moreover, inhibition of c-Abl kinase decreased CLP-induced lung edema and injury. Administration of GDZ824 reduced CLP-induced increases in the number of alveolar neutrophils. Inhibition of c-Abl kinase also markedly attenuated levels of CXC chemokines in the lung and plasma as well as IL-6 levels in the plasma of septic animals. Taken together, this study demonstrates that c-Abl kinase is a potent regulator of NET formation and we conclude that c-Abl kinase might be a useful target to ameliorate lung damage in abdominal sepsis.This study investigates the role of c-Abelson (c-Abl) kinase in neutrophil extracellular trap (NET) formation and inflammation during sepsis. The authors demonstrate that c-Abl kinase plays a pivotal role in NET formation, pulmonary formation of CXC chemokines and lung injury in sepsis. Authors conclude that targeting c-Abl kinase might be a useful strategy to ameliorate local and systemic inflammation in sepsis.

LPIN1 Is a Regulatory Factor Associated With Immune Response and Inflammation in Sepsis.

ObjectivesSepsis is a clinical disease that is typically treated in the intensive care unit, and the complex pathophysiology under this disease has not been thoroughly understood. While ferroptosis is involved in inflammation and infection, its effect in sepsis is still unknown. The study aimed to identify ferroptosis-related genes in sepsis, providing translational potential therapeutic targets.MethodsThe dataset GSE65682 was used to download the sample source from the Gene Expression Omnibus (GEO) database. Consensus weighted gene co-expression network analysis (WGCNA) was performed to find suspected modules of sepsis. The differentially expressed genes (DEGs) most significantly associated with mortality were intersected with those altered by lipopolysaccharide (LPS) treatment and were further analyzed for the identification of main pathways of Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis. The related pathway markers were further verified by qPCR.ResultsA total of 802 blood samples with sepsis were included for WGCNA, which identified 21 modules. Intersected with ferroptosis databases and LPS treatment groups, we identified two ferroptosis-related genes: PEBP1 and LPIN1. Only LPIN1 contributes to a poor outcome. Then, 205 DEGs were further identified according to the high or low LPIN1 expression. Among them, we constructed a gene regulatory network with several transcriptional factors using the NetworkAnalyst online tool and identified that these genes mostly correlate with inflammation and immune response. The immune infiltration analysis showed that lower expression of LPIN1 was related to macrophage infiltration and could be an independent predictor factor of the survival status in sepsis patients. Meanwhile, the multivariate Cox analysis showed that LPIN1 had a significant correlation with survival that was further verified by in vitro and in vivo experiments.ConclusionIn conclusion, LPIN1 could become a reliable biomarker for patient survival in sepsis, which is associated with immune and inflammation status.

Weaning Failure in Critically Ill Patients Is Related to the Persistence of Sepsis Inflammation.

Introduction: Septic patients undergoing mechanical ventilation (MV) often experience difficulty in weaning. Th aim of this study was to determine whether inflammatory biomarkers of sepsis could be indicative of the failure or success of spontaneous breathing trial (SBT) in these patients. Methods: Sixty-five patients on MV (42 septic and 23 intubated for other reasons) fulfilling the criteria for SBT were included in the study. Blood samples were collected right before, at the end of (30 min) and 24 h after the SBT. Serum inflammatory mediators associated with sepsis (IL-18, IL-18BP, TNF) were determined and correlated with the outcome of SBT. Results: A successful SBT was achieved in 45 patients (69.2%). Septic patients had a higher percentage of SBT failure as compared to non-septic patients (85% vs. 15%, p = 0.026), with an odds ratio for failing 4.5 times (OR = 4.5 95%CI: 1.16–17.68, p 0.022). IL-18 levels and the relative mRNA expression in serum were significantly higher in septic as compared to non-septic patients (p < 0.05). Sepsis was independently associated with higher serum IL-18 and TNF levels in two time-point GEE models (53–723, p = 0.023 and 0.3–64, p = 0.048, respectively). IL-18BP displayed independent negative association with rapid shallow breathing index (RSBI) (95% CI: −17.6 to −4, p = 0.002). Conclusion: Sustained increased levels of IL-18 and IL-18BP, acknowledged markers of sepsis, were found to be indicative of SBT failure in patients recovering from sepsis. Our results show that, although subclinical, remaining septic inflammation that sustaines for a long time complicates the weaning procedure. Biomarkers for the estimation of the septic burden and the right time for weaning are needed.

IL-38 Alleviates Inflammation in Sepsis in Mice by Inhibiting Macrophage Apoptosis and Activation of the NLRP3 Inflammasome.

Interleukin- (IL-) 38 is an emerging cytokine with multiple functions involved in infection and immunity. However, the potential role of IL-38 in the host immune response during sepsis remains elusive. Herein, we investigated if macrophages in septic mice express IL-38, the molecular mechanisms behind its expression, and the downstream effects of its expression. In mouse peritoneal macrophages, lipopolysaccharide (LPS) upregulated IL-38 and its receptor IL-36R, and the resulting IL-38 shifted macrophages from a M1 to M2 phenotype. Moreover, exposure to IL-38 alone was sufficient to inhibit macrophage apoptosis and LPS-driven activation of the NOD-, LRR-, and pyrin domain-containing 3 (NLRP3) inflammasome. These effects were partly abrogated by IL-38 downregulation. In septic mice, IL-38 markedly lowered serum concentrations of proinflammatory cytokines and greatly improved survival. Conversely, IL-38 blockade aggravated their mortality. Collectively, these findings present IL-38 as a potent immune modulator that restrains the inflammatory response by suppressing macrophage apoptosis and activation of the NLRP3 inflammasome. IL-38 may help protect organs from sepsis-related injury.

Exosome-Mediated eCIRP Release From Macrophages to Induce Inflammation in Sepsis.

Extracellular cold-inducible RNA-binding protein (eCIRP) is an important damage-associated molecular pattern (DAMP). Despite our understanding of the potentially harmful effects of eCIRP in sepsis, how eCIRP is released from cells remains elusive. Exosomes are endosome-derived extracellular vesicles, which carry proteins, lipids, and nucleic acids to facilitate intercellular communication and several extracellular functions. We hypothesized that eCIRP is released via exosomes to induce inflammation in sepsis. Exosomes isolated from the supernatants of LPS-treated macrophage culture and serum of endotoxemia and polymicrobial sepsis mice showed high purity, as revealed by their unique median sizes ranging between 70 and 126 nm in diameter. eCIRP levels of the exosomes were significantly increased after LPS treatment in the supernatants of macrophage culture, mouse serum, and cecal ligation and puncture (CLP)-induced sepsis mouse serum. Protease protection assay demonstrated the majority of eCIRP was present on the surface of exosomes. Treatment of WT macrophages and mice with exosomes isolated from LPS-treated WT mice serum increased TNFα and IL-6 production. However, treatment with CIRP−/- mice serum exosomes significantly decreased these levels compared with WT exosome-treated conditions. CIRP−/- mice serum exosomes significantly decreased neutrophil migration in vitro compared with WT exosomes. Treatment of mice with serum exosomes isolated from CIRP−/- mice significantly reduced neutrophil infiltration into the peritoneal cavity. Our data suggest that eCIRP can be released via exosomes to induce cytokine production and neutrophil migration. Thus, exosomal eCIRP could be a potential target to inhibit inflammation.

Magnolol protects against acute gastrointestinal injury in sepsis by down-regulating regulated on activation, normal T-cell expressed and secreted.

BACKGROUNDSepsis is a major medical challenge. Magnolol is an active constituent of Houpu that improves tissue function and exerts strong anti-endotoxin and anti-inflammatory effects, but the mechanism by which it reduces intestinal inflammation in sepsis is yet unclear.AIMTo assess the protective effect of magnolol on intestinal mucosal epithelial cells in sepsis and elucidate the underlying mechanisms.METHODSEnzyme-linked immunosorbent assay was used to measure tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), IL-6, and regulated on activation, normal T-cell expressed and secreted (RANTES) levels in serum and ileal tissue in animal studies. The histopathological changes of the ileal mucosa in different groups were observed under a microscope. Cell Counting Kit-8 and cell permeability assays were used to determine the concentration of drug-containing serum that did not affect the activity of Caco2 cells but inhibited lipopolysaccharide (LPS)-induced decrease in permeability. Immunofluorescence and Western blot assays were used to detect the levels of RANTES, inhibitor of nuclear factor kappa-B kinase β (IKKβ), phosphorylated IKKβ (p-IKKβ), inhibitor of nuclear factor kappa-B kinase α (IκBα), p65, and p-p65 proteins in different groups in vitro.RESULTSIn rats treated with LPS by intravenous tail injection in the presence or absence of magnolol, magnolol inhibited the expression of proinflammatory cytokines, IL-1β, IL-6, and TNF-α in a dose-dependent manner. In addition, magnolol suppressed the production of RANTES in LPS-stimulated sepsis rats. Moreover, in vitro studies suggested that magnolol inhibited the increase of p65 nucleation, thereby markedly downregulating the production of the phosphorylated form of IKKβ in LPS-treated Caco2 cells. Specifically, magnolol inhibited the translocation of the transcription factor nuclear factor-kappa B (NF-κB) from the cytosol into the nucleus and down-regulated the expression level of the chemokine RANTES in LPS-stimulated Caco2 cells.CONCLUSIONMagnolol down-regulates RANTES levels by inhibiting the LPS/NF-κB signaling pathways, thereby suppressing IL-1β, IL-6, and TNF-α expression to alleviate the mucosal barrier dysfunction in sepsis.

Meprin and ADAM proteases as triggers of systemic inflammation in sepsis.

Systemic inflammatory disorders (SIDs) comprise a broad range of diseases characterized by dysregulated excessive innate immune responses. Severe forms of SIDs can lead to organ failure and death, and their increasing incidence represents a major issue for the healthcare system. Protease-mediated ectodomain shedding of cytokines and their receptors represents a central mechanism in the regulation of inflammatory responses. The metalloprotease A disintegrin and metalloproteinase (ADAM) 17 is the best-characterized ectodomain sheddase capable of releasing TNF-α and soluble IL-6 receptor, which are decisive factors of systemic inflammation. Recently, meprin metalloproteases were also identified as IL-6 receptor sheddases and activators of the pro-inflammatory cytokines IL-1β and IL-18. In different mouse models of SID, particularly those mimicking a sepsis-like phenotype, ADAM17 and meprins have been found to promote disease progression. In this review, we summarize the role of ADAM10, ADAM17, and meprins in the onset and progression of sepsis and discuss their potential as therapeutic targets.

HIVEP1 Is a Negative Regulator of NF-κB That Inhibits Systemic Inflammation in Sepsis.

Our previous work identified human immunodeficiency virus type I enhancer binding protein 1 (HIVEP1) as a putative driver of LPS-induced NF-κB signaling in humans in vivo. While HIVEP1 is known to interact with NF-ĸB binding DNA motifs, its function in mammalian cells is unknown. We report increased HIVEP1 mRNA expression in monocytes from patients with sepsis and monocytes stimulated by Toll-like receptor agonists and bacteria. In complementary overexpression and gene deletion experiments HIVEP1 was shown to inhibit NF-ĸB activity and induction of NF-ĸB responsive genes. RNA sequencing demonstrated profound transcriptomic changes in HIVEP1 deficient monocytic cells and transcription factor binding site analysis showed enrichment for κB site regions. HIVEP1 bound to the promoter regions of NF-ĸB responsive genes. Inhibition of cytokine production by HIVEP1 was confirmed in LPS-stimulated murine Hivep1-/- macrophages and HIVEP1 knockdown zebrafish exposed to the common sepsis pathogen Streptococcus pneumoniae. These results identify HIVEP1 as a negative regulator of NF-κB in monocytes/macrophages that inhibits proinflammatory reactions in response to bacterial agonists in vitro and in vivo.

Pathogenesis and diagnosis of disseminated intravascular coagulation

Rytis Trojanas1 1Faculty of Medicine, Vilnius University, Vilnius, Lithuania Abstract Background. Disseminated intravascular coagulation is a condition in which systemic coagulation is activated, resulting in large amounts of fibrin in the lumen of small and midsize blood vessels. Thrombi made out of fibrin can disrupt blood flow to internal organs, causing multiple organ dysfunction syndrome. Gradual depletion of platelets and coagulation factors can result in bleeding and hemorrhagic necrosis, which can become the predominant sign of the disseminated intravascular coagulation. Aim: to review the newest literature and articles about disseminated intravascular coagulation, its pathophysiology, diagnostics and treatment options. Methods. The research of literature was conducted using PubMed, Wiley Online Library, Elsevier international databases. Keywords and their combinations were used during research: disseminated intravascular coagulation, coagulopathy, fibrinolysis, platelets, thrombocytopenia. 30 publications were analyzed and included. Conclusions. Disseminated intravascular coagulation is not a disease in itself, rather it occurs as a complication of systemic inflammation in sepsis, major trauma, malignant tumors or obstetric calamities. During systemic inflammation, large amount of tissue factor is exposed, consequently coagulation system is activated. Due to prolonged activation of coagulation, physiological anticoagulation and endogenous fibrinolysis are disturbed, also the activation of platelets is triggered. These processes result in generation of huge amounts of thrombin and fibrin. At the same time the risk of bleeding increase because of usage of platelets and coagulation factors. Disseminated intravascular coagulation diagnosis is based on international diagnostic criteria, which include platelet count, prothrombin time or international normalization ratio and the concentration of fibrin degradation products, like D-dimers. The keystone of treatment in disseminated intravascular coagulation is to treat the disease, which caused the syndrome at the first place. Keywords: disseminated intravascular coagulation, coagulopathy, fibrinolysis, platelets, thrombocytopenia.

RASAL3 Is a Putative RasGAP Modulating Inflammatory Response by Neutrophils.

As first responder cells in host defense, neutrophils must be carefully regulated to prevent collateral tissue injury. However, the intracellular events that titrate the neutrophil’s response to inflammatory stimuli remain poorly understood. As a molecular switch, Ras activity is tightly regulated by Ras GTPase activating proteins (RasGAP) to maintain cellular active-inactive states. Here, we show that RASAL3, a RasGAP, is highly expressed in neutrophils and that its expression is upregulated by exogenous stimuli in neutrophils. RASAL3 deficiency triggers augmented neutrophil responses and enhanced immune activation in acute inflammatory conditions. Consequently, mice lacking RASAL3 (RASAL3-KO) demonstrate accelerated mortality in a septic shock model via induction of severe organ damage and hyperinflammatory response. The excessive neutrophilic hyperinflammation and increased mortality were recapitulated in a mouse model of sickle cell disease, which we found to have low neutrophil RASAL3 expression upon LPS activation. Thus, RASAL3 functions as a RasGAP that negatively regulates the cellular activity of neutrophils to modulate the inflammatory response. These results demonstrate that RASAL3 could serve as a therapeutic target to regulate excessive inflammation in sepsis and many inflammatory disease states.

Evaluation of tissue factor expression on monocytes in the patients with sepsis

Sepsis is nearly always associated with some type of haemostatic disorder. The factors that play main causal role in pathogenesis of these processes are pro-inflammatory cytokines, vascular endothelium, platelets, leukocytes, and tissue factor (TF) expressed on these cells, which is always in an active state. Given a potential relationship between the blood clotting and pathophysiology of sepsis, TF may be considered a biomarker for early diagnosis, risk stratification, and prognosis of disease outcome in sepsis. Objective – to study quantitative content (CD14+CD142+) and the levels of TF expression on monocytes in the patients with sepsis, to analyze the dependence of these parameters on the severity of multiple organ dysfunction according to the SOFA scale, and disease outcomes.67 patients with sepsis were examined. The severity of multiple organ dysfunction/failure was assessed by means of the SOFA score (Sepsis-related Organ Failure Assessments, Sequential Organ Failure Assessment). All the patients were divided in 2 groups based on the severity of their condition and extent of organ failure. Group 1 (n = 30) included the patients diagnosed with sepsis and severe organ dysfunction of 6 points on the SOFA scale; Group 2 (n = 37) consisted of the patients with sepsis and organ dysfunction of 6 points according to the SOFA scores. Blood sampling from patients was made within initial 48 hours after admission and diagnosis. Quantitative content (CD14+CD142+) and the level of expression of tissue factor on monocytes were investigated by flow cytometry. We have found that the content of (CD14+CD142+) cells was significantly higher in patients with sepsis than in healthy individuals (6.03±1.05% vs 0.24±0.02%, p = 0.001), being higher in more severe organ dysfunction (SOFA) vs less severe cases (SOFA) (6.50±0.98% versus 4.42±0.36%, p = 0.05). High level of TF expression on monocytes showed a direct correlation (r 0.71; p = 0.05) with severity of organ dysfunction (SOFA), and it was associated (p = 0.004) with lethal outcome of the disorder. These results suggest that expression of tissue factor on monocytes can serve as a biomarker reflecting the degree of systemic inflammation in sepsis, thus being a criterion for predicting clinical severity and outcome of the disease in patients with sepsis.

GPR43 regulation of mitochondrial damage to alleviate inflammatory reaction in sepsis.

Sepsis is a common critical illness in ICU and always a great difficulty in clinical treatment. GPR43 (G protein-coupled receptor 43) participates in regulating appetite and gastrointestinal peptide secretion to modulate fat decomposition and formation. However, the biological contribution of GPR43 on inflammation of sepsis has not been previously investigated. We investigated the mechanisms of GPR43 gene, which plays a possible role in distinguishing sepsis and contributes to the pathogenesis of sepsis-induced inflammatory reaction. Furthermore, we performed studies with mice induced to sepsis by Cecal Ligation and Puncture (CLP), Knockout GPR43 (GPR43-/-) mice, and Wild Type (WT) mice induced with CLP. In addition, lung tissues and cell samples were analyzed by histology, Quantitative Polymerase Chain Reaction (Q-PCR), Enzyme-linked Immunosorbent (ELISA) Assay, and western blot. GPR43 agonist could significantly reduce inflammation reactions and trigger lung injury in mice with sepsis. As for GPR43-/- mice, the risks of sepsis-induced inflammatory reactions and corresponding lung injury were promoted. On the one hand, the up-regulation of GPR43 gene reduced ROS mitochondrial damage to inhibit inflammatory reactions via the inactivation of NLRP3 Inflammasome by PPARγ/ Nox1/EBP50/ p47phox signal channel. On the other hand, the down-regulation of GPR43 promoted inflammatory reactions in vitro model through the acceleration of ROS-dependently mitochondrial damage by PPARγ/ Nox1/EBP50/ p47phox/ NLRP3 signal channel. These findings indicate that the inhibition of GPR43 as a possible important factor of sepsis may shed lights on the mechanism of sepsis-induced inflammation reaction.

Targeting multiple mediators of sepsis using multifunctional tannic acid-Zn2+-gentamicin nanoparticles

Targeting multiple mediators of sepsis using multifunctional tannic acid-Zn2+-gentamicin nanoparticles

Near-Infrared Spectroscopy-Derived Dynamic Cerebral Autoregulation in Experimental Human Endotoxemia-An Exploratory Study.

Cerebral perfusion may be altered in sepsis patients. However, there are conflicting findings on cerebral autoregulation (CA) in healthy participants undergoing the experimental endotoxemia protocol, a proxy for systemic inflammation in sepsis. In the current study, a newly developed near-infrared spectroscopy (NIRS)-based CA index is investigated in an endotoxemia study population, together with an index of focal cerebral oxygenation.Methods: Continuous-wave NIRS data were obtained from 11 healthy participants receiving a continuous infusion of bacterial endotoxin for 3 h (ClinicalTrials.gov NCT02922673) under extensive physiological monitoring. Oxygenated–deoxygenated hemoglobin phase differences in the (very)low frequency (VLF/LF) bands and the Tissue Saturation Index (TSI) were calculated at baseline, during systemic inflammation, and at the end of the experiment 7 h after the initiation of endotoxin administration.Results: The median (inter-quartile range) LF phase difference was 16.2° (3.0–52.6°) at baseline and decreased to 3.9° (2.0–8.8°) at systemic inflammation (p = 0.03). The LF phase difference increased from systemic inflammation to 27.6° (12.7–67.5°) at the end of the experiment (p = 0.005). No significant changes in VLF phase difference were observed. The TSI (mean ± SD) increased from 63.7 ± 3.4% at baseline to 66.5 ± 2.8% during systemic inflammation (p = 0.03) and remained higher at the end of the experiment (67.1 ± 4.2%, p = 0.04). Further analysis did not reveal a major influence of changes in several covariates such as blood pressure, heart rate, PaCO2, and temperature, although some degree of interaction could not be excluded.Discussion: A reversible decrease in NIRS-derived cerebral autoregulation phase difference was seen after endotoxin infusion, with a small, sustained increase in TSI. These findings suggest that endotoxin administration in healthy participants reversibly impairs CA, accompanied by sustained microvascular vasodilation.

Sepsis Inflammation Impairs the Generation of Functional Dendritic Cells by Targeting Their Progenitors

BackgroundSepsis is a complex systemic immune dysfunction syndrome induced by infection. Sepsis has a high mortality rate, with most patients dying due to systemic organ failure or secondary infection. Dendritic cells (DCs) are professional antigen-presenting cells. Upon infection with microbes, DCs are activated to induce adaptive immune responses for controlling infection. DC generation and function are impaired during sepsis; however, the underlying mechanisms remain largely unknown.MethodsPeripheral blood samples from sepsis patients were collected to examine DC subsets, DC progenitors, and apoptosis of DCs by flow cytometer. In vitro induction of DCs from hematopoietic stem/progenitor cells were established and a variety of sepsis-associated inflammatory mediators [e.g., interferon-gamma (IFN-γ), interleukin-1beta (IL-1β), tumor necrosis factor-alpha (TNF-α) and granulocyte-colony stimulating factor (G-CSF)] and Lipopolysaccharide (LPS) were determined for the impact on DC generation and function in vitro.ResultsOur results demonstrate that sepsis-induced systemic inflammation impairs the capacity of hematopoietic stem and progenitor cells (HSPCs) to produce DCs, including conventional DCs (cDCs) and plasmacytoid DCs (pDCs). We investigated peripheral blood (PB) samples from 34 pediatric patients on days 1 to 7 following diagnosis. Compared to healthy donors (n = 18), the sepsis patients exhibited a significantly fewer percentage and number of pDCs and cDCs, and a lower expression of antigen presenting molecule HLD-DR and co-stimulatory molecules (e.g., CD86) on the surface of DCs. This sepsis-induced DC impairment was associated with significantly increased apoptotic death of DCs and marked decreases of progenitor cells that give rise to DCs. Furthermore, we observed that among the tested sepsis-associated cytokines (e.g., IFN-γ, IL-1β, TNF-α, and G-CSF), G-CSF and IFN-γ impaired DC development from cultured HSPCs. G-CSF also markedly decreased the expression of HLA-DR on HSPC-derived DCs and their cytokine production, including IL-12 and IFN-β.ConclusionsCollectively, these findings indicate that sepsis impairs the survival of functional DCs and their development from HSPCs. Strategies for improving DC reconstitution following sepsis may restore DC progenitors and their associated function.