Epithelial intrinsic inflammasomes direct host defense against gut microbes

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PROJECT SUMMARY Enteric infections and their associated sequelae, including pain, nausea, inflammation and diarrhea, are major causes of morbidity and mortality worldwide, particularly in children. Being at the frontline of intestinal host defense, intestinal epithelial cells (IECs) are the frequent target of enteric pathogens. It is generally believed that during enteric infections, the gut epithelium and overlying mucus layer, which are at the forefront of the host-microbial interface, primarily provide a physical barrier against invading pathogens, whereas any innate immune response that occurs within the intestinal mucosa is largely driven by the immune/inflammatory cells resident in the lamina propria. In contrast, recent studies, including our own, ascribe an unprecedented role for IECs as important players in gut innate immune responses. Together, these studies unequivocally showed that canonical and non-canonical inflammasomes in IECs promote host defense and inflammatory responses at early stages of infection by the model enteric pathogen, Salmonella enterica serovar Typhimurium. The primary objective of this application is to define the contribution of IEC inflammasomes to antimicrobial host defenses in the gut. Our general hypothesis is that IEC intrinsic inflammasomes coordinate several protective and anti-microbial pathways at the gut mucosal surface. Two integrated specific aims are proposed to test this hypothesis. First, we will delineate the protective role of IEC inflammasomes against enteric pathogens in vitro and in vivo, and assess the regulation and temporal contribution of IEC canonical and non-canonical inflammasomes during infection. Second, we will elucidate goblet cell-specific inflammasome-dependent defense responses. Completion of this proposal will close a significant knowledge gap regarding the impact of epithelium-intrinsic inflammasomes on intestinal antimicrobial defense, homeostasis and disease development.