Complement 5a receptor-mediated neutrophil dysfunction is associated with a poor outcome in sepsis.
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ABSTRACT:
SUBMITTER: Xu R
PROVIDER: S-EPMC4711680 | biostudies-other | 2016 Jan
REPOSITORIES: biostudies-other
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Project description:Sepsis is a life-threatening systemic inflammatory condition causing approximately 11 million annual deaths worldwide. Although key hyperinflammation-based organ dysfunctions that drive disease pathology have been recognized, our understanding of the factors that predispose patients to septic mortality is limited. Due to the lack of reliable prognostic measures, the development of appropriate clinical management that improves patient survival remains challenging. Here, we discovered that a subpopulation of CD49chigh neutrophils with dramatic upregulation of the complement component 1q (C1q) gene expression arises during severe sepsis. We further found that deceased septic patients failed to maintain C1q protein expression in their neutrophils, whereas septic survivors expressed higher levels of C1q. In mouse sepsis models, blocking C1q with neutralizing antibodies or conditionally knocking out C1q in neutrophils led to a significant increase in septic mortality. Apoptotic neutrophils release C1q to control their own clearance in critically injured organs during sepsis; thus, treatment of septic mice with C1q drastically increased survival. These results suggest that neutrophil C1q is a reliable prognostic biomarker of septic mortality and a potential novel therapeutic target for the treatment of sepsis.
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Project description:Pre-eclampsia (PE) is a life-threatening multisystem disorder leading to maternal and neonatal mortality and morbidity. Emerging evidence showed that activation of the complement system is implicated in the pathological processes of PE. However, little is known about the detailed cellular and molecular mechanism of complement activation in the development of PE. In this study, we reported that complement 5a (C5a) plays a pivotal role in aberrant placentation, which is essential for the onset of PE. We detected an elevated C5a deposition in macrophages and C5a receptor (C5aR) expression in trophoblasts of pre-eclamptic placentas. Further study showed that C5a stimulated trophoblasts towards an anti-angiogenic phenotype by mediating the imbalance of angiogenic factors such as soluble fms-like tyrosine kinase 1 (sFlt1) and placental growth factor (PIGF). Additionally, C5a inhibited the migration and tube formation of trophoblasts, while, C5aR knockdown with siRNA rescued migration and tube formation abilities. We also found that maternal C5a serum level was increased in women with PE and was positively correlated with maternal blood pressure and arterial stiffness. These results demonstrated that the placental C5a/C5aR pathway contributed to the development of PE by regulating placental trophoblasts dysfunctions, suggesting that C5a may be a novel therapeutic possibility for the disease.
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Project description:The maladaptive response to infection leading to the clinical syndrome of sepsis is highly heterogeneous, confounding immunotherapy trials. Here we establish the pathophysiology of a sepsis response endotype informative for immune state, disease severity, outcome and therapy. We applied whole blood single-cell multiomics (272,993 cells, n=39 individuals) and found patients with this endotype had increased IL1R2+ immature neutrophils, confirmed using CyTOF (n=41 samples) and RNA-sequencing (n=677 individuals), and upregulated STAT3 programs with plasma cytokine profiles of emergency granulopoiesis (EG). We characterised sepsis hematopoietic stem cells (29,336 cells, n=27 samples) with multiomics, and demonstrated endotype-specific EG transcriptional skewing together with STAT3 and EG master regulator CEBPB epigenetic signatures. Our findings establish an immunohematopoietic basis for a deleterious sepsis endotype and nominate IL-6/G-CSF as potential therapeutic targets.
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Project description:BackgroundIt is not known whether brain magnetic resonance imaging (MRI) abnormalities in pediatric sepsis are associated with clinical outcomes. Study objectives were to (1) determine the prevalence and type of sepsis-related neuroimaging abnormalities evident on clinically indicated brain MRI in children with sepsis and (2) test the association of these abnormalities with mortality, new disability, length of stay (LOS), and MRI indication.MethodsRetrospective cohort study of 140 pediatric patients with sepsis and a clinically indicated brain MRI obtained within 60 days of sepsis onset at a single, large academic pediatric intensive care unit (PICU). Two radiologists systematically reviewed the first post-sepsis brain MRI and determined which abnormalities were sepsis-related. Outcomes compared in patients with versus without sepsis-related MRI abnormalities.ResultsPICU mortality was 7%. Thirty patients had one or more sepsis-related MRI abnormality, yielding a prevalence of 21% (95% confidence interval 15%, 28%). Among those, 53% (16 of 30) had sepsis-related white matter signal abnormalities; 53% (16 of 30) sepsis-related ischemia, infarction, or thrombosis; and 27% (eight of 30) sepsis-related posterior reversible encephalopathy. Patients with one or more sepsis-related MRI abnormality had increased mortality (17% vs 5%; P = 0.04), new neurological disability at PICU discharge (32% vs 11%; P = 0.03), and longer PICU LOS (median 18 vs 11 days; P = 0.04) compared with patients without.ConclusionsIn children with sepsis and a clinically indicated brain MRI, 21% had a sepsis-related MRI abnormality. Sepsis-related MRI abnormalities were associated with increased mortality, new neurological disability, and longer PICU LOS.
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Project description:BackgroundSepsis is a severe systemic inflammatory disorder manifested by a dysregulated immune response to infection and multi-organ failure. Numerous studies have shown that elevated ferritin levels exist as an essential feature during sepsis and are able to suggest patients' prognoses. At the same time, the specific mechanism of ferritin-induced inflammatory injury remains unclear.MethodsHyper-ferritin state during inflammation was performed by injecting ferritin into a mouse model and demonstrated that injection of ferritin could induce a systemic inflammatory response and increase neutrophil extracellular trap (NET) formation.Padi4-/-, Elane-/- and Cybb-/- mice were used for the NETs formation experiment. Western blot, immunofluorescence, ELISA, and flow cytometry examined the changes in NETs, inflammation, and related signaling pathways.ResultsFerritin induces NET formation in a peptidylarginine deiminase 4 (PAD4), neutrophil elastase (NE), and reactive oxygen species (ROS)-dependent manner, thereby exacerbating the inflammatory response. Mechanistically, ferritin induces the expression of neutrophil macrophage scavenger receptor (MSR), which promotes the formation of NETs. Clinically, high levels of ferritin in patients with severe sepsis correlate with NETs-mediated cytokines storm and are proportional to the severity of sepsis-induced lung injury.ConclusionsIn conclusion, we demonstrated that hyper-ferritin can induce systemic inflammation and increase NET formation in an MSR-dependent manner. This process relies on PAD4, NE, and ROS, further aggravating acute lung injury. In the clinic, high serum ferritin levels are associated with elevated NETs and worse lung injury, which suggests a poor prognosis for patients with sepsis. Our study indicated that targeting NETs or MSR could be a potential treatment to alleviate lung damage and systemic inflammation during sepsis. Video Abstract.
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Project description:The project examines the mechanisms of neutrophil dysfunction during sepsis. Our work uncovered the central role of cell free circulating histones in eliminating mature neutrophil in favour of immature cells and characterized the mechanisms that regulate their release following systemic infection. Mature and immature neutrophil Ly6Ghigh and Ly6Glow populations isolated from the spleens of WT and TCRα-deficient mice either naïve or infected with C. albicans were characterized. In addition, these populations were compared to neutrophils isolated from WT mice receiving Clodronate-liposomes and recombinant G-CSF. These studies demonstrated that T-cell derived histones drive the release of G-CSF in the spleen and progressively eliminate mature neutrophils by shortening their lifespan. Finally, we conducted proteomic analysis of plasmas isolated from patients with microbial sepsis to correlate markers of neutrophil death to plasma cytokine and histone levels, confirming the pathogenic role these molecules play during sepsis in humans.
2022-12-13 | PXD032961 | Pride
Project description:PURPOSE: The endothelial protein C receptor (EPCR) negatively regulates the coagulopathy and inflammatory response in sepsis. Mechanisms controlling the expression of cell-bound and circulating soluble EPCR (sEPCR) are still unclear. Moreover, the clinical impact of EPCR shedding and its potential value to predict sepsis progression and outcome remain to be established. METHODS: We investigated the time course of plasma sEPCR over the 5 first days (D) of severe sepsis in 40 patients. RESULTS: No significant difference was observed when comparing sEPCR at admission (D1) to healthy volunteers and to patients with vasculitis. We report that the kinetics profile of plasma sEPCR in patients was almost stable at the onset of sepsis with no change from D1 to D4 and then a significant decrease at D5. This pattern of release was consistently observed whatever the level of sEPCR at D1. Characteristics of patients or of infections (except Gram negative) had no or little critical influence on the sEPCR profile. However, we found that sEPCR kinetics was clearly associated with patient's outcome (D28 survival). We demonstrate that a significant but moderate (<15% of basal level) and transient increase in sEPCR level at D2 is associated with poor outcome at D28. CONCLUSION: Severe sepsis, at the onset, only triggers moderate quantitative changes in plasma sEPCR levels. Our findings suggest that in severe sepsis, an early (at D2), transient but significant increase in circulating sEPCR may be detrimental suggesting that sEPCR could provide an early biological marker of sepsis outcome.
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Project description:BACKGROUND & AIMS:The macrophage scavenger receptor 1 (Msr1, also called SRA) is a pattern recognition receptor primarily expressed on myeloid cells, which plays an important role in the maintenance of immune homeostasis. Since MSR1 expression was upregulated in the livers of patients with fulminant hepatitis (FH), we investigated the functional mechanism of Msr1 in FH pathogenesis. METHODS:Msr1-deficient (Msr1-/-) mice and their wild-type (WT) littermates were infected with mouse hepatitis virus strain-A59 (MHV-A59) to induce FH, and the levels of tissue damage, serum alanine aminotransferase, inflammatory cytokines and complement component 5a (C5a) were measured and compared. Liver injury was studied after MHV infection with or without neutrophil depletion. RESULTS:Our results showed that Msr1-/- mice were resistant to MHV-induced hepatitis. Treatment with the C5a receptor antagonist (C5aRa) diminished the differences in inflammatory responses and liver injury between MHV-infected wild-type and Msr1-/- mice, suggesting that C5a-induced pro-inflammatory response plays a critical role in the Msr1-mediated regulation of FH pathogenesis. We demonstrated that Msr1 efficiently enhanced transforming growth factor-activated kinase-1 phosphorylation in neutrophils upon MHV-A59 stimulation, thereby promoting the activation of the extracellular signal-regulated kinase pathway and subsequent NETosis formation. Moreover, we provided evidence that blockage of Msr1 attenuated the liver damage caused by MHV-A59 infection. CONCLUSIONS:Msr1 promotes the pathogenesis of virus-induced FH by enhancing induction of neutrophil NETosis and subsequent complement activation. Targeting Msr1 may be employed as a new immunotherapeutic strategy for FH. LAY SUMMARY:Virus-induced fulminant hepatitis (FH) is a disease with a high mortality worldwide. Enhanced levels of macrophage scavenger receptor 1 (Msr1) in the liver of patients with FH and of murine experimental FH indicated Msr1 plays a role in the pathogenesis of FH. Herein, we demonstrate that mice deficient in Msr1 are resistant to FH induced by MHV-A59, and the Msr1 inhibitor fucoidan suppresses the progression of FH in mice. Our study suggests that use of drugs inhibiting MSR1 function could be beneficial to patients with FH.
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Project description:Exposure to traumatic or infectious insults results in a rapid activation of the complement cascade as major fluid defense system of innate immunity. The complement system acts as a master alarm system during the molecular danger response after trauma and significantly contributes to the clearance of DAMPs and PAMPs. However, depending on the origin and extent of the damaged macro- and micro -milieu, the complement system can also be either excessively activated or inhibited. In both cases, this can lead to a maladaptive immune response and subsequent multiple cellular and organ dysfunction. The arsenal of complement-specific drugs offers promising strategies for various critical conditions after trauma, hemorrhagic shock, sepsis, and multiple organ failure. The imbalanced immune response needs to be detected in a rational and real-time manner before the translational therapeutic potential of these drugs can be fully utilized. Overall, the temporal-spatial complement response after tissue trauma and during sepsis remains somewhat enigmatic and demands a clinical triad: reliable tissue damage assessment, complement activation monitoring, and potent complement targeting to highly specific rebalance the fluid phase innate immune response.
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