Project description:Sepsis impacts males and females differently. Males have higher incidence, illness severity and mortality in sepsis than females. In this study, we use mouse models of fecal-induced peritonitis (FIP) to study sex disparities in sepsis. Male mice show higher illness severity, physiological derangement and end-organ dysfunction compared to females. Sex-biased outcome was driven by gonadal sex but not chromosome-linked gene effects. The results of this study indicate that male-biased sepsis severity is driven by impaired infection tolerance in males due to sex-biased mechanisms of mitochondrial function. We did not find differences in infection resistance or canonical immune/inflammatory pathways between males and female mice. Here we performed RNA-sequencing on mouse liver hepatocytes of uninfected and septic males and females.
Project description:Severely-afflicted COVID-19 patients can exhibit disease manifestations representative of sepsis, including acute respiratory distress syndrome and multiple organ failure. We hypothesized that diagnostic tools used in managing all-cause sepsis, such as clinical criteria, biomarkers, and gene expression signatures, should extend to COVID-19 patients. Here we analyzed the whole blood transcriptome of 124 early (1-5 days post-hospital admission) and late (6-20 days post-admission) sampled patients with confirmed COVID-19 infections from hospitals in Quebec, Canada. Mechanisms associated with COVID-19 severity were identified between severity groups (ranging from mild disease to the requirement for mechanical ventilation and mortality), and established sepsis signatures were assessed for dysregulation. Specifically, gene expression signatures representing pathophysiological events, namely cellular reprogramming, organ dysfunction, and mortality, were significantly enriched and predictive of severity and lethality in COVID-19 patients. Mechanistic endotypes reflective of distinct sepsis aetiologies and therapeutic opportunities were also identified in subsets of patients, enabling prediction of potentially-effective repurposed drugs. The expression of sepsis gene expression signatures in severely-afflicted COVID-19 patients indicates that these patients should be classified as having severe sepsis. Accordingly, in severe COVID-19 patients, these signatures should be strongly considered for the mechanistic characterization, diagnosis, and guidance of treatment using repurposed drugs.
Project description:Identifying at first clinical presentation gene expression signatures that predict subsequent severity will allow clinicians to identify the most at risk groups of patients, and also enable appropriate antibiotic use. Accordingly, we characterized the blood immune profiles of patients with early/pre-sepsis to identify signatures reflecting disease severity, organ dysfunction, mortality, and specific endotypes/mechanisms.
Project description:Background: Sepsis involves aberrant immune responses to infection, but the exact nature of this immune dysfunction remains poorly defined. Bacterial endotoxins like lipopolysaccharide (LPS) are potent inducers of inflammation, which has been associated with the pathophysiology of sepsis, but repeated exposure can also induce a suppressive effect known as endotoxin tolerance or cellular reprogramming. It has been proposed that endotoxin tolerance might be associated with the immunosuppressive state that was primarily observed during late-stage sepsis. However, this relationship remains poorly characterised. Here we clarify the underlying mechanisms and timing of immune dysfunction in sepsis. Methods: We defined a gene expression signature characteristic of endotoxin tolerance. Gene-set test approaches were used to correlate this signature with early sepsis, both newly and retrospectively analysing microarrays from 593 patients in 11 cohorts. Then we recruited a unique cohort of possible sepsis patients at first clinical presentation in an independent blinded controlled observational study to determine whether this signature was associated with the development of confirmed sepsis and organ dysfunction. Findings: All sepsis patients presented an expression profile strongly associated with the endotoxin tolerance signature (p < 0.01; AUC 96.1%). Importantly, this signature further differentiated between suspected sepsis patients who did, or did not, go on to develop confirmed sepsis, and predicted the development of organ dysfunction. Interpretation: Our data support an updated model of sepsis pathogenesis in which endotoxin tolerance-mediated immune dysfunction (cellular reprogramming) is present throughout the clinical course of disease and related to disease severity. Thus endotoxin tolerance might offer new insights guiding the development of new therapies and diagnostics for early sepsis. For the RNA-Seq study reported here, 73 patients were recruited with deferred consent at the time of first examination in an emergency ward based on the opinion of physicians that there was a potential for the patient's condition to develop into sepsis. These were retrospectively divided into groups based on clinical features and compared to 11 non-urgent surgical controls.
Project description:THREE ARE SOME TECH PROBLEMS WHICH WILL BE SOLVED SOON! Sepsis, the dysregulated host response to infection causing life-threatening organ dysfunction, is an unmet global health challenge. Here we apply high-throughput tandem mass spectrometry to delineate the plasma proteome for 2622 sepsis and comparator samples (non-infected critical illness, postoperative inflammation and healthy volunteers) involving 4553 liquid chromatography-mass spectrometry analyses in a single batch, at 100 samples/day. We show how this scale of data can establish shared and specific proteins, pathways and co-expression modules in sepsis, and be integrated with paired leukocyte transcriptomic data (n=837 samples) using matrix decomposition. We map the landscape of the host response in sepsis including changes over time, and identify features relating to etiology, clinical phenotypes and severity. This work reveals novel subphenotypes informative for sepsis response state, disease processes and outcome, highlights potential biomarkers, pathways and processes for drug targets, and advances a systems-based precision medicine approach to sepsis.
Project description:Investigatation into how genes with sex-differential expression profiles are distributed among the chromosomes in Drosophila. Assayed the expression of 14,142 predicted transcripts in competitive hybridizations and found a dramatic underrepresentation of X-chromosome genes showing high relative expression in male. This is the first report of sex-biased expression of the full (predicted) genome. Findings indicate that there is significant sex-biased expression, especially in gonads. Genes showing sex-biased gene expression profiles are likely to have sex-biased functions. Keywords: other
Project description:Background: Sepsis involves aberrant immune responses to infection, but the exact nature of this immune dysfunction remains poorly defined. Bacterial endotoxins like lipopolysaccharide (LPS) are potent inducers of inflammation, which has been associated with the pathophysiology of sepsis, but repeated exposure can also induce a suppressive effect known as endotoxin tolerance or cellular reprogramming. It has been proposed that endotoxin tolerance might be associated with the immunosuppressive state that was primarily observed during late-stage sepsis. However, this relationship remains poorly characterised. Here we clarify the underlying mechanisms and timing of immune dysfunction in sepsis. Methods: We defined a gene expression signature characteristic of endotoxin tolerance. Gene-set test approaches were used to correlate this signature with early sepsis, both newly and retrospectively analysing microarrays from 593 patients in 11 cohorts. Then we recruited a unique cohort of possible sepsis patients at first clinical presentation in an independent blinded controlled observational study to determine whether this signature was associated with the development of confirmed sepsis and organ dysfunction. Findings: All sepsis patients presented an expression profile strongly associated with the endotoxin tolerance signature (p < 0.01; AUC 96.1%). Importantly, this signature further differentiated between suspected sepsis patients who did, or did not, go on to develop confirmed sepsis, and predicted the development of organ dysfunction. Interpretation: Our data support an updated model of sepsis pathogenesis in which endotoxin tolerance-mediated immune dysfunction (cellular reprogramming) is present throughout the clinical course of disease and related to disease severity. Thus endotoxin tolerance might offer new insights guiding the development of new therapies and diagnostics for early sepsis.
Project description:Both sepsis and acute respiratory distress syndrome (ARDS) rely on imprecise clinical definitions leading to heterogeneity, which has contributed to negative trials. Because circulating protein/DNA complexes have been implicated in sepsis and ARDS, we aimed to develop a proteomic signature of DNA-bound proteins to discriminate between children with sepsis with and without ARDS. We performed a prospective case-control study in 12 children with sepsis with ARDS matched to 12 children with sepsis without ARDS on age, severity of illness score, and source of infection. We performed co-immunoprecipitation and downstream proteomics in plasma collected ≤ 24 h of intensive care unit admission. Expression profiles were generated, and a random forest classifier was used on differentially expressed proteins to develop a signature which discriminated ARDS. The classifier was tested in six independent blinded samples. Neutrophil and nucleosome proteins were over-represented in ARDS, including two S100A proteins, superoxide dismutase (SOD), and three histones. Random forest produced a 10-protein signature that accurately discriminated between children with sepsis with and without ARDS. This classifier perfectly assigned six independent blinded samples as having ARDS or not. We validated higher expression of the most informative discriminating protein, galectin-3-binding protein, in children with ARDS. Our methodology has applicability to isolation of DNA-bound proteins from plasma. Our results support the premise of a molecular definition of ARDS, and give preliminary insight into why some children with sepsis, but not others, develop ARDS.
Project description:Millions of sepsis survivors annually face long-term neuropsychiatric sequelae of their illness. Corticosteroids are frequently administered in sepsis, and their use affects neuropsychiatric outcomes, but the mechanisms are unknown. We used the cecal ligation and puncture method to induce acute infection in mice and test the hypothesis that corticosteroid treatment during illness has long-term effects on hippocampal function. Functional phenotyping and hippocampal RNA-sequencing were performed in the same survivor mice to identify underlying mechanisms of behavioral and neuroendocrine outcomes. Long-term CLP survivors exhibited anxiety-like behavior, increased central hypothalamic-pituitary-adrenal (HPA) axis activity, and persistent systemic and neuro-inflammation. The relationship between gene expression and behavior suggested a protective role for inflammation and oxidative metabolism after CLP. Corticosterone treatment during illness had distinct effects on hippocampal function in survivors, including object memory impairment. The long-term behavioral effects of corticosterone treatment were associated with persistent downregulation of activity-dependent gene expression in the hippocampus. The results suggest that corticosteroid treatment for sepsis influences hippocampal function in survivors via long-lasting changes to basal hippocampal activity. Neural activity, inflammation, and oxidative metabolism should be explored as future treatment targets to modify neuropsychiatric outcomes in sepsis survivors.
Project description:Background: Stalk-eyed flies (family Diopsidae) are a model system for studying sexual selection due to the presence of elongated and sexually dimorphic eye-stalks in many species. Recent genomic studies on these flies have revealed a neo-X chromosome and evidence of gene movement onto or off of this X chromosome. To determine if sex linkage and gene movement are related to sexual dimorphism and sexual conflict, we compared gene expression between males and females using oligonucleotide microarrays and RNA from either developing eyestalk tissue or adult heads from a dimorphic species, Teleopsis dalmanni, or from developing eyestalk tissue in a congeneric monomorphic species, T. quinqueguttata. Results: Comparison of gene expression between the sexes for 3,748 genes indicates that dosage compensation is present due to elevated expression of X-linked genes in males. However, sex-biased expression was detected in 26% of the genes present in eye-antennal imaginal discs of larval T. dalmanni. Functional annotation reveals that female-biased genes are associated with transcription, anatomical development and cell communication in the nucleus, while male-biased genes are associated with metabolism and the mitochondria. Comparison of gene expression between experiments identified 140 genes with concordant sex-biased expression in the larval and adult tissues of T. dalmanni and 17 genes with identical sex-biased expression between species. There were only five reversals of sex-biased expression across experiments. In T. dalmanni, male-biased genes are more common on autosomes than on the X while female-biased genes are more common on the X in T. quinqueguttata. Female-biased expression is especially common among genes that moved onto the ancestral X while male-biased expression is more common among genes that moved onto an autosome. Conclusions: Genes with sex-biased expression exhibit different functions in each sex as expected if sexual conflict has influenced their evolution. The strong relationship between sex-biased expression and gene movement found in this study is consistent with resolution of sexual conflict by an RNA- or DNA-mediated process that moves genes between chromosomes. Measurement of gene expression in additional species should provide a more complete picture of how gene expression change occurs over evolutionary time in these extraordinary flies. Two-condition experiment, female vs. male RNA using larval eye discs for two species (Teleopsis dalmanni, Teleopsis quinqueguttata), and adult heads for one species (Teleopsis dalmanni).