Project description:TLRs are considered important for innate immune responses that combat bacterial infections. Here, the role of TLRs in severe septic peritonitis using the colon ascendens stent peritonitis (CASP) model was examined. We demonstrate that mice deficient for MyD88 and TRIF had markedly reduced bacterial numbers both in peritoneal cavity and peripheral blood, indicating that bacterial clearance in this model is inhibited by TLR signals. Moreover, survival of Myd88-/-;TrifLps2/Lps2 mice was significantly improved. The lack of TLR signals prevented the excessive induction of inflammatory cytokines and of IL 10. Notably, the expression of IFN-gamma, which has an essential protective role in septic peritonitis, and of IFN-regulated genes including several p47 and p65 GTPases as well as IP 10 was independent of TLR signaling. These results provide evidence that, in severe septic peritonitis, TLR deficiency balances the innate immune response in a favorable manner by attenuating deleterious responses such as excessive cytokine release, while leaving intact protective IFN-gamma production. In this dataset, expression data of genes induced by septic peritonitis in spleens from TLR-deficient and wildtype mice are included. 3 groups (septic TLR-deficient mice, septic wildtype mice, and untreated wildtype mice) with 4 replicates each.
Project description:TLRs are considered important for innate immune responses that combat bacterial infections. Here, the role of TLRs in severe septic peritonitis using the colon ascendens stent peritonitis (CASP) model was examined. We demonstrate that mice deficient for MyD88 and TRIF had markedly reduced bacterial numbers both in peritoneal cavity and peripheral blood, indicating that bacterial clearance in this model is inhibited by TLR signals. Moreover, survival of Myd88-/-;TrifLps2/Lps2 mice was significantly improved. The lack of TLR signals prevented the excessive induction of inflammatory cytokines and of IL 10. Notably, the expression of IFN-gamma, which has an essential protective role in septic peritonitis, and of IFN-regulated genes including several p47 and p65 GTPases as well as IP 10 was independent of TLR signaling. These results provide evidence that, in severe septic peritonitis, TLR deficiency balances the innate immune response in a favorable manner by attenuating deleterious responses such as excessive cytokine release, while leaving intact protective IFN-gamma production.
Project description:Host defense against bacterial and fungal infections diminishes with age. In humans, this is thought to be caused in part by a decline in neutrophil responses. However, it remains unclear whether a similar decline in neutrophil function occurs in mice. Here, we show that old mice have a reduced capacity to clear pathogenic E. coli during septic peritonitis. Neutrophil recruitment to the peritoneum was elevated during lipopolysaccharide (LPS)-induced septic peritonitis but not aseptic peritonitis. Neutrophils from old mice showed reduced chemoattractant-induced reactive oxygen species (ROS) production upon priming with LPS but not GM-CSF/TNF. Phagocytosis and degranulation were reduced in a partially LPS-dependent manner, whereas NETosis was impaired independently of LPS. The chemoattractant-stimulated production of PIP3 was reduced upon priming with LPS but not GM-CSF/TNF, whereas PI(4,5)P2 levels were constitutively low. Unexpectedly, chemotaxis was normal regardless of priming pathway, as were the chemoattractant-stimulated activities of Rac1 and Rac2. The expression of 5% of neutrophil proteins was deregulated in old age. Granule proteins, particularly cathepsins and serpins, as well as toll-like receptor (TLR) pathway proteins and membrane receptors were upregulated, whereas chromatin and RNA regulators were downregulated. Upregulation of Cd180 and downregulation of MyD88 may contribute to the impaired LPS priming and LPS-dependent PIP3 production. In summary, all major neutrophil responses except chemotaxis decline with age in mice, particularly upon LPS priming. This LPS-TLR4 pathway dependence resolves some of the controversy regarding the effects of age on murine neutrophils and confirms mice are an appropriate model for the declining human neutrophil function.
Project description:Septic cardiac dysfunction is a key feature of severe sepsis and septic shock, contributing to multiorgan dysfunction syndrome and death. It has been established that persistent beta adrenergic stimulation is detrimental in sepsis, and that specific beta 1 blockade mitigates excessive systemic inflammation and improves myocardial function. The aim of this study was to investigate the effects of specific beta 1 blocker esmolol on septic mouse myocardium by genomic and proteomic techniques. We also evaluated survival of septic mice and systemic inflammation under esmolol treatment.
Project description:The role of ICA cells in septic cardiomyopathy is unknown. Here we show that norepinephrine (NE) secretion from ICA cells is increased through activation of Toll-like receptor 4 (TLR4) to aggravate myocardial TNF-α production and dysfunction by lipopolysaccharide (LPS). In ICA cells, LPS activated TLR4-MyD88/TRIF-AP-1 signaling that promoted NE biosynthesis through expression of tyrosine hydroxylase, but did not trigger TNF-α production due to impairment of p65 translocation. Our findings suggest that ICA cells may be a potential therapeutic target for septic cardiomyopathy.
Project description:Toll-like receptor 4 (TLR4), the receptor of gram-negative bacterial endotoxin, is present on the intestinal epithelium and plays pivotal roles in intestinal epithelial differentiation and host defense. To better understand TLR4 on the intestinal epithelium, the ileum samples from wild type mice and mice lacking TLR4 in the intestinal epithelium (TLR4ΔIEC) were subjected to RNA-seq analysis to interrogate the transcriptome. We mapped about 20 million sequence reads per sample to the mouse genome and identified 86477 genes in the ileum of wild type and TLR4ΔIEC mice. 455 genes were differentially expressed between wild type and TLR4ΔIEC mice and 1037 genes were absent either from wild type or TLR4ΔIEC mice with G-factor value 0.015 and Δ cutoff value 0.54. Pathway analysis via IPA indicated some impacted canonical KEGG pathways such as DNA replication, PPAR signaling, Toll-like receptor signaling, cytokine-cytokine interaction, adherens junction, Jak-STAT signaling, and tight junction.
Project description:Septic cardiac dysfunction is a key feature of severe sepsis and septic shock, contributing to multiorgan dysfunction syndrome and death. It has been established that persistent beta adrenergic stimulation is detrimental in sepsis, and that specific beta 1 blockade mitigates excessive systemic inflammation and improves myocardial function. The aim of this study was to investigate the effects of specific beta 1 blocker esmolol on septic mouse myocardium by genomic and proteomic techniques. We also evaluated survival of septic mice and systemic inflammation under esmolol treatment. C57BL/6 mice were rendered septic by 2 models: cecal ligature and perforation (CLP) and intraperitoneal injection of lipopolysaccharides (LPS). Effects of esmolol on myocardium were assessed by microarray technique. Total RNA were isolated and purified from a 30mg sample of the heart of 6 groups of 8 animals, depending on the sepsis model and the treatment. The labeled cDNA from the treated animals were hybridized against the labeled cDNA from the untreated animals with 2 dye-swaps done for each sepsis model.
Project description:Regulated by histone acetyltransferases and deacetylases (HDACs), histone acetylation is a key epigenetic mechanism controlling chromatin structure, DNA accessibility, and gene expression. HDAC inhibitors induce growth arrest, differentiation, and apoptosis of tumor cells and are used as anticancer agents. Here we describe the effects of HDAC inhibitors on microbial sensing by macrophages and dendritic cells in vitro and host defenses against infection in vivo. HDAC inhibitors down-regulated the expression of numerous host defense genes, including pattern recognition receptors, kinases, transcription regulators, cytokines, chemokines, growth factors, and costimulatory molecules as assessed by genome-wide microarray analyses or innate immune responses of macrophages and dendritic cells stimulated with Toll-like receptor agonists. HDAC inhibitors induced the expression of Mi-2β and enhanced the DNA-binding activity of the Mi-2/NuRD complex that acts as a transcriptional repressor of macrophage cytokine production. In vivo, HDAC inhibitors increased the susceptibility to bacterial and fungal infections but conferred protection against toxic and septic shock. Thus, these data identify an essential role for HDAC inhibitors in the regulation of the expression of innate immune genes and host defenses against microbial pathogens.
Project description:We assayed leukocyte global gene expression for a prospective validation cohort of 221 adult patients admitted to UK intensive care units with sepsis due to community acquired pneumonia or faecal peritonitis. 10 samples from patients scheduled for elective cardiac surgery were also assayed as non-septic controls. We assigned all samples to sepsis response signature groups after performing unsupervised analysis of the transcriptomic data.