Project description:The outcome of viral infection is extremely heterogeneous at the cellular level, and infected cells only sometimes activate innate immunity. Here we assess how the genetic variation inherent in viral populations contributes to this heterogeneity. We do this by developing a new approach to determine both the cellular transcriptome and full-length sequences of all viral genes in single influenza-infected cells. Infections that activate an innate-immune response in single cells are associated with viral defects that include amino-acid mutations, internal deletions, and failure to express key genes. However, immune activation remains stochastic in cells infected by virions with these defects, and sometimes occurs even in cells infected by virions that express unmutated copies of all genes. Our work shows that the genetic variation present in influenza virus populations substantially contributes to but does not fully explain the heterogeneity in infection outcome and immune activation in single infected cells.
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:MV130 is an inactivated polybacterial mucosal vaccine that confers protection to patients against recurrent respiratory infections, including those of viral etiology. However, its mechanism of action remains poorly understood. Herein, we observe that intranasal prophylaxis with MV130 modulates the lung immune landscape and provides long term heterologous protection against viral respiratory infections in mice. Intranasal administration of MV130 provided protection against systemic candidiasis in wild-type and Rag1-deficient mice lacking functional lymphocytes, indicative of innate immune-mediated protection. Moreover, pharmacological inhibition of trained immunity with metformin abrogated the protection conferred by MV130 against Influenza A virus respiratory infection. MV130 induced reprogramming of mouse bone marrow progenitor cells and human monocytes, promoting an enhanced cytokine production that relied on metabolic and epigenetic shifts. Our results unveil that the mucosal a dministration of a fully inactivated bacterial vaccine provides protection against viral infections by a mechanism associated with the induction of trained immunity. This SuperSeries is composed of the SubSeries listed below.
Project description:Type-I interferon (IFN-I) is essential to establish antiviral innate immunity. Unanchored (or free) polyubiquitin (poly-Ub) has been shown to regulate IFN-I responses, however few unanchored poly-Ub interactors are known. To identify factors regulated by unanchored poly-Ub in a physiological setting, we developed an approach to isolate unanchored poly-Ub from lung tissue and identified the DEAH-box RNA helicase DHX16 as a factor that enhances IFN-I production. Silencing of DHX16 in cells and in vivo diminished IFN-I responses against influenza virus. DHX16-dependent IFN-I production requires RIG-I and unanchored K48-poly-Ub synthesized by the E3 Ub ligase TRIM6. DHX16 recognizes a signal in influenza segments that undergo splicing and requires its intact RNA helicase motif for direct, high-affinity interactions with specific viral RNAs. Our study establishes DHX16 as a potentiator of RIG-I-mediated IFN-I production and recognizes a mechanism for activation of antiviral immunity requiring unanchored poly-Ub and the viral RNA recognition activity of DHX16
Project description:Monocyte differentiation into macrophages represents one of the cornerstone processes in innate host defense. In addition, immunological imprinting of either tolerance or trained immunity after an initial infection determines the functional fate of innate immune cells and the susceptibility of the host to secondary infections. Here we comprehensively characterize the epigenetic profiles of these functional states relative to healthy adult naM-CM-/ve monocytes. Inflammatory and metabolic pathways are strongly modulated in the derived macrophages, including decreased activation of inflammasome components. The cAMP-dependent signaling pathway is remodeled and adrenergic signaling was functionally implicated in trained innate immunity induction in vivo. Interestingly, M-oM-^AM-"-Glucan trains innate immune cells through extensive remodeling of distal regulatory region-bound histone acetylation, resulting in a sizeable exclusive epigenomic signature. Accordingly, genome-wide transcription factor footprint analysis reveals a specific transcription factor repertoire at trained cell-specific enhancers when recouped with epigenetic data, forming a rich hypothesis generator to manipulate innate immunity. Monocytes were pre-incubated either with cell culture medium (RPMI), M-NM-2-glucan (5M-BM-5g/mL) or with LPS (100ng/mL), for 24 hours in a total volume of 10 mL. After a wash-out, cells were cultured in RPMI supplemented with 10% human pool serum. Monocytes were collected at different time points (0 h and 6 d after treatment) and counted before further treatment for chromatin immunoprecipitation, RNA or DNaseI treatment. Different donor Buffycoats (BC) were used as independent replicates. Replicates were generated for all the profiles including ChIPseq,RNAseq and DNaseIseq.
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:Human rhinovirus and influenza virus infections of the upper airway lead to colds and the flu and can trigger exacerbations of lower airway diseases including asthma and chronic obstructive pulmonary disease. Despite modest advances in the diagnosis and treatment of infections by these viruses, novel diagnostic and therapeutic targets are still needed to differentiate between the cold and the flu, since the clinical course of influenza can be severe while that of rhinovirus is usually more mild. In our investigation of influenza and rhinovirus infection of human respiratory epithelial cells, we used a systems approach to identify the temporally changing patterns of host gene expression from these viruses. After infection of human bronchial epithelial cells (BEAS-2B) with rhinovirus, influenza virus or co-infection with both viruses, we studied the time-course of host gene expression changes over three days. From these data, we constructed a transcriptional regulatory network model that revealed shared and unique host responses to these viral infections such that after a lag of 4-8 hours, most cell host responses were similar for both viruses, while divergent host cell responses appeared after 24-48 hours. The similarities and differences in gene expression after epithelial infection of rhinovirus, influenza virus, or both viruses together revealed qualitative and quantitative differences in innate immune activation and regulation. These differences help explain the generally mild outcome of rhinovirus infections compared to influenza infections which can be much more severe. Human bronchial epithelial cells (BEAS-2B) were infected with rhinovirus, influenza virus or both viruses and RNAs were then profiled at 10 time points (2, 4, 6, 8, 12, 24, 26, 48, 60 and 72hrs)
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.