Project description:The etiology of trauma-hemorrhage shock-induced acute lung injury has been difficult to elucidate due, at least in part, to the inability of in vivo studies to separate the non-injurious pulmonary effects of trauma-hemorrhage from the tissue injurious ones. To circumvent this in vivo limitation, we utilized a model of trauma-hemorrhagic shock (T/HS) in which T/HS-lung injury was abrogated by dividing the mesenteric lymph duct. In this way, it was possible to separate the pulmonary injurious response from the non-injurious systemic response to T/HS by comparing the pulmonary molecular response of rats subjected to T/HS which did and did not develop lung injury as well as to non-shocked rats. Utilizing high-density oligonucleotide arrays and treatment group comparisons of whole lung tissue collected at 3 hours after the end of the shock or sham-shock period, 139 of the 8,799 assessed genes were differentially expressed. Experiment Overall Design: Four groups of rats (n=3) were studied in order to identify changes in pulmonary gene expression associated with T/HS, both in the presence and absence of lung injury. These included trauma-sham shock (T/SS) rats which had a laparotomy (trauma) but were not subjected to hemorrhagic shock. These rats had no lung injury and served as controls for rats which were subjected to T/HS (laparotomy plus 90 min of shock) and had lung injury. Differences in gene expression between these two groups would represent both the effects of hemorrhagic shock as well as lung injury. To distinguish the gene response of hemorrhagic shock from the gene response associated with lung injury, gene expression was also compared between T/HS rats (hemorrhage and lung injury) and rats subjected to T/HS plus lymph duct ligation (T/HS-LDL), since the T/HS-LDL rats experienced hemorrhagic shock but had no measurable lung injury. Lastly, to identify hemorrhagic shock- modified genes, the pulmonary gene response of T/HS-LDL (hemorrhage without lung injury) were compared to rats subjected to T/SS plus LDL (no hemorrhage or lung injury). Three hours after the end of the 90 min shock or sham-shock period (i.e. 4.5 hrs after the induction of T/HS), the rats were sacrificed and specimens harvested for genechip analysis and histology.

Project description:Zaire ebolavirus (ZEBOV) is among the deadliest known human pathogens, causing severe hemorrhagic fever with high case fatality rates ranging from 70-90%. The lack of effective vaccines or treatment available for ZEBOV renders this pathogen as a significant global biodefense threat, as evidenced by the current, highly lethal outbreak of a novel ZEBOV variant in western Africa. Existing mouse models of lethal ZEBOV infection do not reproduce hallmark symptoms of Ebola hemorrhagic fever (EHF) including prolonged blood coagulation, acute hepatitis, disseminated intravascular coagulation (DIC), and death from hemorrhagic shock, thus restricting pathogenesis studies to non-human primates (NHP). This has prevented rapid evaluation of countermeasures in outbreak scenarios, and impeded a comprehensive understanding of how host responses to infection contribute to severe EHF disease. Here we demonstrate that mice from the Collaborative Cross (CC), a panel of reproducible, recombinant inbred animals that span the genetic breadth of three murine subspecies, are susceptible to a spectrum of disease phenotypes following ZEBOV infection. In contrast to C57Bl6/J mice, which develop lethal disease without symptoms of EHF, CC recombinant inbred intercrossed (CC-RIX) lines develop either complete resistance to lethal disease or severe EHF characterized by prolonged coagulation times and 100% mortality. Disease resistance and survival is not dependent on viral tropism, as both resistant and EHF-susceptible lines show similar inflammation and cytopathic effect in target organs. Transcriptomics reveal potential mechanisms for both induction of severe hemorrhage in EHF mediated by IL-6 and vascular activation, and resistance to lethal infection by induction of lymphocyte differentiation and cellular adhesion. These data demonstrate that host responses specific to unique genetic backgrounds determine susceptibility to hemorrhagic syndrome independent of virus replication. The CC represents a novel mouse model for studying EHF pathogenesis, and we anticipate that it will be applied immediately to developing and evaluating therapeutic countermeasures. Microarrays were performed on liver and spleen samples from mice collected at days 1, 3, and 5 post-infection with mouse adapted Zaire ebolavirus or from time-matched mock-infected animals.

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