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IL17A genetic variation is associated with altered susceptibility to Gram-positive infection and mortality of severe sepsis.

ABSTRACT: Interleukin 17A (IL17A) plays a key role in host defense against microbial infection including Gram-positive bacteria. Genetic factors contribute to the host defense, but the role of IL17A single nucleotide polymorphisms (SNPs) has not yet been investigated in severe sepsis. Therefore, we hypothesized that SNPs in the IL17A gene alter susceptibility to infection and clinical outcome of severe sepsis.We tested for the association of IL17A SNPs with susceptibility to infection and clinical outcome of severe sepsis using two cohorts of European ancestry (derivation cohort, St Paul's Hospital (SPH), n = 679; validation cohort, Vasopressin and Septic Shock Trial (VASST), n = 517). The primary outcome variable was susceptibility to Gram-positive bacterial infection. The secondary outcome variable was 28-day mortality.Of four tested IL17A tag SNPs (rs4711998, rs8193036, rs2275913, rs1974226), rs1974226 SNP was associated with altered susceptibility to Gram-positive infection in the derivation SPH cohort (corrected P = 0.014). Patients having the rs1974226 GG genotype were more susceptible to Gram-positive infection, compared to AG/AA genotype in the two cohorts of severe sepsis (SPH, P = 0.0036, odds ratio (OR) 2.19, 95% confidence interval (CI) 1.28-3.72; VASST, P = 0.011, OR 1.95, 95%CI 1.16-3.27) and in the subgroup having lung infection (P = 0.017, OR 1.90, 95%CI 1.12-3.21). Furthermore, the IL17A rs1974226 G allele was associated with increased 28-day mortality in two cohorts (SPH, adjusted OR 1.44, 95%CI 1.04-2.02, P = 0.029; VASST, adjusted OR 1.67, 95%CI 1.17-2.40, P = 0.0052).IL17A genetic variation is associated with altered susceptibility to Gram-positive infection and 28-day mortality of severe sepsis.

SUBMITTER: Nakada TA

PROVIDER: S-EPMC3334805 | biostudies-literature | 2011

REPOSITORIES: biostudies-literature

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IL17A genetic variation is associated with altered susceptibility to Gram-positive infection and mortality of severe sepsis.

Nakada Taka-aki TA Russell James A JA Boyd John H JH Walley Keith R KR

Critical care (London, England) 20111025 5

<h4>Introduction</h4>Interleukin 17A (IL17A) plays a key role in host defense against microbial infection including Gram-positive bacteria. Genetic factors contribute to the host defense, but the role of IL17A single nucleotide polymorphisms (SNPs) has not yet been investigated in severe sepsis. Therefore, we hypothesized that SNPs in the IL17A gene alter susceptibility to infection and clinical outcome of severe sepsis.<h4>Methods</h4>We tested for the association of IL17A SNPs with susceptibil ...[more]

PMID: 22026963

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Project description:Objective: It is unclear whether the host response of gram-positive sepsis differs from gram-negative sepsis at a transcriptome level. Using microarray technology, we compared the gene-expression profiles of gram-positive sepsis and gram-negative sepsis in critically ill patients. Design: A prospective cross-sectional study. Setting: A 20-bed general intensive care unit of a tertiary referral hospital. Patients: Seventy-two patients admitted to the intensive care unit. Interventions: Intravenous blood was collected for leukocyte separation and RNA extraction. Microarray experiements were then performed examing the expression level of 19,232 genes in each sample. Measurements and Main Results: There was no difference in the expression profile between gram-positive and gram-negative sepsis. The finding remained unchanged even when genes with lower expression level were included or after statistical stringency was lowered. There were, however, ninety-four genes differentially expressed between sepsis and control patients. These genes included those involved in immune regulation, inflammation and mitochondrial function. Hierarchical cluster analysis confirmed that the difference in gene expression profile existed between sepsis and control patients, but not between gram-positive and gram-negative patients. Conclusion: Gram-positive and gram-negative sepsis share a common host response at a transcriptome level. These findings support the hypothesis that the septic response is non-specific and is designed to provide a more general response that can be elicited by a wide range of different micro-organisms. The study included seventy-two critically ill patients admitted to the intensive care unit (ICU) of Nepean Hospital, Sydney, Australia. Of these, fifty-five patients were diagnosed to have sepsis, as confirmed by microbiological culture. The remaining seventeen patients did not have sepsis and were therefore used as controls. The study was approved by the hospital ethics committee and informed consent was obtained from all patients or their relatives. Patient Samples. Whole blood was taken from each patient on admission to ICU. Neutrophils were separated from whole blood using density-gradient separation with Ficoll-PaqueP P(Amersham). Subsequent neutrophil RNA extraction was performed using guanidinium thiocyanate (Ambion). Microarray Experiment. The neutrophil RNA was converted to cDNA, fluorescently labeled and hybridized to its complimentary sequences on the microarray (Invitrogen). The fluorescent signals on each micrroarray were captured using the GenePix 4000B laser scanner (Axon Instruments). Expression level of each gene was represented by the intensity of its fluorescent signal. Data Extraction. All signal intensity values were processed using background-subtraction method. Prior to analysis, all values were log-transformed and normalized by fitting a print-tip group Lowess curve. Normalization minimizes bias due to dye chemistry, signal intensity or location of a gene on the array. It ensures the detection of genes that are truly differentially expressed, instead of those caused by experimental artifacts or variation in the hybridization process. After normalization, genes that had more than 50% of data missing were removed. We then selected genes that had at least 80% of the data showing two-fold changes from the geneâs median values. After filtering, 1617 genes were available for further analysis.

Project description:BackgroundTumor necrosis factor (TNF) and TNF receptor superfamily (TNFR)-mediated immune response play an essential role in the pathogenesis of severe sepsis. Studies examining associations of TNF and lymphotoxin-? (LTA) single nucleotide polymorphisms (SNPs) with severe sepsis have produced conflicting results. The objective of this study was to investigate whether genetic variation in TNF, LTA, TNFRSF1A and TNFRSF1B was associated with susceptibility to or death from severe sepsis in Chinese Han population.Methodology/principal findingsTen SNPs in TNF, LTA, TNFRSF1A and TNFRSF1B were genotyped in samples of patients with severe sepsis (n = 432), sepsis (n = 384) and healthy controls (n = 624). Our results showed that rs1800629, a SNP in the promoter region of TNF, was significantly associated with risk for severe sepsis. The minor allele frequency of rs1800629 was significantly higher in severe sepsis patients than that in both healthy controls (P(adj) = 0.00046, odds ratio (OR)(adj) = 1.92) and sepsis patients (P(adj) = 0.002, OR(adj) = 1.56). Further, we investigated the correlation between rs1800629 genotypes and TNF-? concentrations in peripheral blood mononuclear cells (PBMCs) of healthy volunteers exposed to lipopolysaccharides (LPS) ex vivo, and the association between rs1800629 and TNF-? serum levels in severe sepsis patients. After exposure to LPS, the TNF-? concentration in culture supernatants of PBMCs was significantly higher in the subjects with AA+AG genotypes than that with GG genotype (P = 0.007). Moreover, in patients with severe sepsis, individuals with AA+AG genotypes had significantly higher TNF-? serum concentrations than those with GG genotype (P(adj) = 0.02). However, there were no significant associations between SNPs in the four candidate genes and 30 day mortality for patients with severe sepsis.Conclusions/significanceOur findings suggested that the functional TNF gene SNP rs1800629 was strongly associated with susceptibility to severe sepsis, but not with lethality in Chinese Han population.

Project description:Sepsis is an inflammatory response to pathogens (such as Gram‑positive and Gram‑negative bacteria), which has high morbidity and mortality in critically ill patients. The present study aimed to identify the key genes in Gram‑positive and Gram‑negative sepsis. GSE6535 was downloaded from Gene Expression Omnibus, containing 17 control samples, 18 Gram‑positive samples and 25 Gram‑negative samples. Subsequently, the limma package in R was used to screen the differentially expressed genes (DEGs). Hierarchical clustering was conducted for the specific DEGs in Gram‑negative and Gram‑negative samples using cluster software and the TreeView software. To analyze the correlation of samples at the gene level, a similarity network was constructed using Cytoscape software. Functional and pathway enrichment analyses were conducted for the DEGs using DAVID. Finally, stochastic perturbation was used to determine the significantly differential functions between Gram‑positive and Gram‑negative samples. A total of 340 and 485 DEGs were obtained in Gram‑positive and Gram‑negative samples, respectively. Hierarchical clustering revealed that there were significant differences between control and sepsis samples. In Gram‑positive and Gram‑negative samples, myeloid cell leukemia sequence 1 was associated with apoptosis and programmed cell death. Additionally, NADH:ubiquinone oxidoreductase subunit S4 was associated with mitochondrial respiratory chain complex I assembly. Stochastic perturbation analysis revealed that NADH:ubiquinone oxidoreductase subunit B2 (NDUFB2), NDUFB8 and ubiquinol‑cytochrome c reductase hinge protein (UQCRH) were associated with cellular respiration in Gram‑negative samples, whereas large tumor suppressor kinase 2 (LATS2) was associated with G1/S transition of the mitotic cell cycle in Gram‑positive samples. NDUFB2, NDUFB8 and UQCRH may be biomarkers for Gram‑negative sepsis, whereas LATS2 may be a biomarker for Gram‑positive sepsis. These findings may promote the therapies of sepsis caused by Gram‑positive and Gram‑negative bacteria.

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IL17A genetic variation is associated with altered susceptibility to Gram-positive infection and mortality of severe sepsis.

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IL17A genetic variation is associated with altered susceptibility to Gram-positive infection and mortality of severe sepsis.

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