Project description:Peripheral blood was collected from human patients infected with influenza A virus only or in addition with bacterial pathogens and at different days after hospital admission. For comparison, blood from healthy controls was collected. Gene expression differences were detected in influenza and bacterial infections compared to healthy controls, and at various days post infection.
Project description:Influenza associated bacterial super-infections have devastating impacts on the lung and can result in increased risk of mortality. New strains of influenza circulate throughout the population yearly promoting the establishment of immune memory. Nearly all individuals have some degree of influenza memory prior to adulthood. Due to this we sought to understand the role of immune memory during bacterial super-infections. An influenza heterotypic immunity model was established using influenza A/PR/8/34 and A/X31. We report here that influenza experienced mice are more resistant to secondary bacterial infection with methicillin-resistant Staphylococcus aureus as determined by wasting, bacterial burden, pulmonary inflammation, and lung leak, despite significant ongoing lung remodeling. Multidimensional flow cytometry and lung transcriptomics revealed significant alterations in the lung environment in influenza-experienced mice compared with naïve animals. These include changes in the lung monocyte and T cell compartments, characterized by increased expansion of influenza tetramer specific CD8+ T cells. The protection that was seen in memory experienced mouse model is associated with the reduction in inflammatory mechanisms making the lung less susceptible to damage and subsequent bacterial colonization. These findings provide insight into how influenza heterotypic immunity re-shapes the lung environment and the immune response to a re-challenge event, which is highly relevant to the context of human infection.
Project description:Introduction: Diagnosis of severe influenza pneumonia remains challenging because of the lack of correlation between presence of influenza virus and patient’s clinical status. We conducted gene expression profiling in the whole blood of critically ill patients to identify a gene signature that would allow clinicians to distinguish influenza infection from other causes of severe respiratory failure (e.g. bacterial pneumonia, non-infective systemic inflammatory response syndrome). Methods: Whole blood samples were collected from critically ill individuals and assayed on Illumina HT-12 gene expression beadarrays. Differentially expressed genes were determined by linear mixed model analysis and over-represented biological pathways determined using GeneGo MetaCore. Results: The gene expression profile of H1N1 influenza A pneumonia was distinctly different from bacterial pneumonia and systemic inflammatory response syndrome. The influenza gene expression profile is characterized by up-regulation of genes from cell cycle regulation, apoptosis and DNA-damage response pathways. In contrast, no distinctive gene-expression signature was found in patients with bacterial pneumonia or systemic inflammatory response syndrome. The gene expression profile of influenza infection persisted through five days of follow-up. Furthermore, in patients with primary H1N1 influenza A infection who subsequently developed bacterial co-infection, the influenza gene-expression signature remained unaltered, despite the presence of a super-imposed bacterial infection. Conclusions: The whole blood expression profiling data indicates that the host response to influenza pneumonia is distinctly different from that caused by bacterial pathogens. This information may speed up identification of the cause of infection in patients presenting with severe respiratory failure, allowing appropriate patient care to be undertaken more rapidly. Daily PAXgene samples for up to 5 days for; influenza A pneumonia patients (n=8), bacterial pneumonia patients (n=16), mixed bacterial and influenza A pneumonia patients (n=3), systemic inflammatory response patients (SIRS, n=13). Days 1 and 5 PAXgene samples for healthy control individuals
Project description:Secondary bacterial infections (‘superinfection’) are a major reason for excessive mortality and hospitalizations during influenza virus infections. Here we present a longitudinal study of gene-expression changes in murine lungs during superinfection, with an initial influenza A virus (IAV) infection and a subsequent S. pneumonia (SP) infection. In addition to the well characterized impairment of the innate immune response, we identified superinfection-specific alterations in endothelial functions, including rapid downregulation in angiogenic activity and vascular regulators. Superinfection-specific alterations were also evident in analysis of cellular states related to the host’s immune resistance against pathogens. We found that only a few hours after secondary bacterial challenge, superinfected mice manifested an excessive induction of immune resistance, and in addition, there was a substantial rewiring of the resistance program: interferon-regulated genes are switched from positive to negative correlations with resistance, whereas genes of fatty-acid metabolism are switched from negative to positive correlations with resistance. Thus, the transcriptional resistance state is reprogrammed toward repressed interferon signaling and induced fatty acid metabolism. Our findings suggest new insights into the remodeling of the host defense upon superinfection, providing promising targets for future therapeutic interventions.
Project description:Longitudinal Gene expression profiling of whole blood from critically ill influenza and bacterial pneumonia patients. In addition before vs 7 days post influenza vaccination volunteer samples are assayed. 3 groups of samples. First is bacterial pneumonia patients with 6 subjects sampled for up to 5 days. Second group is severe influenza infection with 4 subjects sampled for up to 5 days. Third group is influenza vaccination with 18 subjects sampled before and 7 days post vaccination.
Project description:Longitudinal Gene expression profiling of whole blood from critically ill influenza and bacterial pneumonia patients. In addition before vs 7 days post influenza vaccination volunteer samples are assayed.
Project description:Influenza virus infection leads to global cardiac proteome remodeling during convalescence MTD project_description "Influenza virus infections lead to more than 500,000 hospitalizations in the U.S. every year. Patients with cardiovascular diseases have been shown to be at high risk of influenza mediated cardiac complications. Importantly, recent reports have provided clinical data supporting a direct link between laboratory-confirmed influenza virus infection and adverse cardiac events. However, the molecular mechanisms of how influenza virus infection induces detrimental cardiac changes, even after resolution of the pulmonary infection, is completely unknown.
Project description:Introduction: Diagnosis of severe influenza pneumonia remains challenging because of the lack of correlation between presence of influenza virus and patient’s clinical status. We conducted gene expression profiling in the whole blood of critically ill patients to identify a gene signature that would allow clinicians to distinguish influenza infection from other causes of severe respiratory failure (e.g. bacterial pneumonia, non-infective systemic inflammatory response syndrome). Methods: Whole blood samples were collected from critically ill individuals and assayed on Illumina HT-12 gene expression beadarrays. Differentially expressed genes were determined by linear mixed model analysis and over-represented biological pathways determined using GeneGo MetaCore. Results: The gene expression profile of H1N1 influenza A pneumonia was distinctly different from bacterial pneumonia and systemic inflammatory response syndrome. The influenza gene expression profile is characterized by up-regulation of genes from cell cycle regulation, apoptosis and DNA-damage response pathways. In contrast, no distinctive gene-expression signature was found in patients with bacterial pneumonia or systemic inflammatory response syndrome. The gene expression profile of influenza infection persisted through five days of follow-up. Furthermore, in patients with primary H1N1 influenza A infection who subsequently developed bacterial co-infection, the influenza gene-expression signature remained unaltered, despite the presence of a super-imposed bacterial infection. Conclusions: The whole blood expression profiling data indicates that the host response to influenza pneumonia is distinctly different from that caused by bacterial pathogens. This information may speed up identification of the cause of infection in patients presenting with severe respiratory failure, allowing appropriate patient care to be undertaken more rapidly.
Project description:Each infectious agent represents a unique combination of pathogen-associated molecular patterns that interact with specific pattern-recognition receptors expressed on immune cells. Therefore, we surmised that the blood immune cells of individuals with different infections might bear discriminative transcriptional signatures. Gene expression profiles were obtained for 131 peripheral blood samples from pediatric patients with acute infections caused by influenza A virus, Gram-negative (Escherichia coli) or Gram-positive (Staphylococcus aureus and Streptococcus pneumoniae) bacteria. Thirty-five genes were identified that best discriminate patients with influenza A virus infection from patients with either E coli or S pneumoniae infection. These genes classified with 95% accuracy (35 of 37 samples) an independent set of patients with either influenza A, E coli, or S pneumoniae infection. A different signature discriminated patients with E coli versus S aureus infections with 85% accuracy (34 of 40). Furthermore, distinctive gene expression patterns were observed in patients presenting with respiratory infections of different etiologies. Thus, microarray analyses of patient peripheral blood leukocytes might assist in the differential diagnosis of infectious diseases. Keywords: expression analysis
Project description:Influenza virus infection leads to global cardiac proteome remodeling during convalescence MTD project_description "Influenza virus infections lead to more than 500,000 hospitalizations in the U.S. every year. Patients with cardiovascular diseases have been shown to be at high risk of influenza mediated cardiac complications. Importantly, recent reports have provided clinical data supporting a direct link between laboratory-confirmed influenza virus infection and adverse cardiac events. However, the molecular mechanisms of how influenza virus infection induces detrimental cardiac changes, even after resolution of the pulmonary infection, is completely unknown. We performed global quantitative proteomics as well as phosphoproteomics in this study.