Project description:Severe bacterial (pneumococcal) infections are commonly associated with influenza and are significant contributors to the excess morbidity and mortality of influenza. Disruption of lung tissue integrity during influenza participates in bacterial pulmonary colonization and dissemination out of the lungs. Interleukin (IL)-22 has gained considerable interest in anti-inflammatory and anti-infection immunotherapy over the last decade. In the current study, we investigated the effect of exogenous IL-22 delivery on the outcome of bacterial superinfection post-influenza. Our data show that exogenous treatment of influenza-infected mice with recombinant IL-22 reduces bacterial dissemination out of the lungs but is without effect on pulmonary bacterial burden. We describe an IL-22 specific gene signature in the lung tissue of IAV-infected (and naïve) mice that might explain the observed effects. Indeed, exogenous IL-22 modulates gene expression profile in a way suggesting a reinforcement of tissue integrity. Our results open the way to alternative approaches for limiting post-influenza bacterial superinfection, particularly systemic bacterial invasion.
Project description:Chronic obstructive pulmonary disease (COPD) collectively refers to chronic and progressive lung diseases causing not fully reversible limitations in airflow. COPD patients are at high risk for severe respiratory symptoms upon influenza virus infection. Airway epithelial cells provide the first-line antiviral defense, but whether their susceptibility and response to influenza virus infection changes in COPD has not been elucidated. Therefore, this study aimed to i) compare the susceptibility of COPD- and control-derived airway epithelium to influenza virus, and ii) assess protein changes during influenza virus infection by quantitative proteomics. Fluorescent stainings confirmed expression of human- and avian-type influenza virus receptors in primary human bronchial epithelial cells (phBECs) from COPD patients (n=4) and controls (n=3) differentiated at the air-liquid interface. Subjects were closely matched in age, sex, and smoking history and, for COPD-derived phBECs, included stage II (n=2), stage III (n=1) and stage IV (n=1). Proteomics of fully differentiated phBECs pre- and post-influenza A virus infection with A/Puerto Rico/8/34 (PR8) revealed no significant differences between GOLD stage II/ III COPD (n=3) and control phBECs in terms of flu receptor expression, cell type composition, virus replication, or protein profile pre- and post-infection. In contrast, COPD GOLD stage IV phBECs (n=1) showed a distinct pattern of flu receptor expression and a typical COPD phenotype as assessed by a literature-derived panel of 20 proteins and quantification of cell type composition. Independent of health state, proteomics showed a robust antiviral response to influenza virus infection, as well as upregulation of several novel influenza virus-regulated proteins.
Project description:An effective immune response to influenza A virus (IAV) requires two arms: host resistance, which restricts viral replication, and disease tolerance that limits tissue damage caused by the immune response to IAV. Interestingly, fatal influenza infections are more often associated with dysregulated inflammation, rather than an inability to control viral replication, highlighting the importance of mechanisms involved in disease tolerance to IAV. Here, we show that cyclophilin D (CypD), a mitochondrial protein known to regulate cell death and cytokine production, protects against IAV infection through disease tolerance. Mice deficient in CypD (CypD-/-) exhibit enhanced susceptibility to IAV infection, despite comparable myeloid immune responses and intact antiviral immunity. Instead, CypD-/- susceptibility was due to pulmonary tissue damage, caused by a lack of the cytokine IL-22 that protects the lung epithelium. We found the necessary source of IL-22 following IAV infection to be conventional natural killer (NK) cells that failed to reach the airways of infected CypD-deficient mice, as a result of dysregulated lymphopoiesis in the bone marrow. Importantly, following infection, a single administration of recombinant IL-22 in the airways abrogated pulmonary damage and rescued CypD-/- mice. Thus, the CypD/IL-22/NK cell axis is critical in immunity to IAV by promoting disease tolerance, limiting lung tissue damage and maintaining pulmonary function.
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: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:To assess whether transcriptional differences exist in the epithelial tissue and the inflammatory infiltrate of invasive Aspergillus tracheobronchitis in patients with severe influenza or severe COVID-19, we performed GeoMx spatial transcriptomics on four biopsy samples in total: two of patients with influenza-associated pulmonary aspergillosis (IAPA) and two of patients with COVID-19-associated pulmonary aspergillosis (CAPA). Several regions of interest (ROIs) were delineated in each biopsy sample, and transcriptomic data was derived of each of these ROIs using GeoMx with a whole transcriptome atlas with SARS-CoV-2 spike-in.
Project description:Life-threatening pulmonary influenza can be caused by inborn errors of type I and III IFN immunity. We report a 5 year-old child with severe pulmonary influenza at 2 years. She is homozygous for a loss-of-function IRF9 allele. Her cells activate gamma-activated factor (GAF) STAT1 homodimers but not interferon-stimulated gene factor 3 (ISGF3) trimers (STAT1/STAT2/IRF9) in response to IFN-α2b. The transcriptome induced by IFN-α2b in the patient’s cells is much narrower than that of control cells; however, induction of a subset of interferon-stimulated gene transcripts remains detectable. In vitro, the patient’s cells do not control three respiratory viruses, influenza A virus (IAV), parainfluenza virus, and respiratory syncytial virus. These phenotypes are rescued by wild-type IRF9, whereas silencing IRF9 expression in control cells increases viral replication. However, the child has controlled various common viruses in vivo, including respiratory viruses other than IAV. Our findings show that human IRF9- and ISGF3-dependent type I and III IFN responsive pathways are essential for controlling IAV.
Project description:Exosomes are extracellular vesicles secreted by cells that have an important biological function in intercellular communication by transferring biologically active proteins, lipids, and RNAs to neighbouring or distant cells. While a role for exosomes in antimicrobial defence has recently emerged, currently very little is known regarding the nature and functional relevance of exosomes generated in vivo, particularly during an active viral infection. Here, we characterised exosomes released into the airways during influenza virus infection. We show that these vesicles dynamically change in protein composition over the course of infection, increasing expression of host proteins with known anti-influenza activity, and viral proteins with the potential to trigger host immune responses. We show that exosomes released into the airways during influenza virus infection trigger pulmonary inflammation and carry viral antigen that can be utilized by antigen presenting cells to drive the induction of a cellular immune response. Moreover, we show that attachment factors for influenza virus, namely α2,3 and α2,6-linked sialic acids, are present on the surface of airway exosomes and these vesicles have the ability to neutralize influenza virus, thereby preventing the virus from binding and entering target cells. These data reveal a novel role for airway exosomes in the antiviral innate immune defence against influenza virus infection.
Project description:Disruption of pulmonary vascular homeostasis is a central feature of viral pneumonia, wherein endothelial cell (EC) death and subsequent angiogenic responses represent critical determinants of the outcome of severe lung injury. A more granular understanding of the fundamental mechanisms driving reconstitution of the lung endothelium is necessary to facilitate therapeutic targeting of vascular repair. Here, we applied single-cell RNA sequencing (scRNA-seq) to profile lung ECs from mice on D0, D20 and D30 post influenza infection. Our data revealed the dynamics of endothelial subsets during influenza injury.
Project description:The biological basis for the increased severity of influenza A viruses during the 2009 influenza pandemic remains unclear. Intra-host evolution of quasispecies and strong inflammation were identified as important hallmarks of severe pandemic H1N1 influenza A virus 2009 (A(H1N1)pdm09) infection. HA-222D/G quasispecies of A(H1N1)pdm09 were shown to undergo fast evolution and to cause severe influenza in human and mice. Here, we analysed the whole genome transcriptional response of mice infected with the A/Jena/5258/09 (mpJena/5258) virus over a period of 12 days to gain insights into the pathogenesis of A(H1N1)pdm09 HA-222D/G quasispecies on a molecular level. Remarkably, the transcriptional response to severe mpJena/5258 showed biphasic expression profile for the majority of genes which was never shown before. The gene expression analysis shows first peak with 968 differentially expressed genes at day 2 post infection (p.i.), followed by a stagnant recovery phase with 359 differentially expressed genes at day 4 p.i., and a second peak with 1001 differentially expressed genes at day 7 p.i., finally followed by a recovery phase. Using a reverse engineering strategy, a regulatory network was inferred to identify key interactions leading to severe pathogenesis of mpJena/5258. Known regulatory interactions were extracted by Pathway Studio 9.0 and softly integrated during network inference. The results demonstrate a hyper-responsive action and a positive feedback loop of IFN gamma (Ifng), Stat1 and Tlr3 signalling during mpJena/5258 infection. In conclusion, mpJena/5258 infection is associated with biphasic gene expression profile and a positive feedback mechanism of Ifng which correlates with the evolution of HA-222D/G quasispecies and leads to overwhelming immune response. A significant correlation were found between the co-expression action of three genes (Ifng, Stat1 and Tlr3) with a phenomenological clinical symptom score.