Formyl peptide receptors as mediators of intestinal mucosal homeostasis

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DESCRIPTION (provided by applicant): The gastrointestinal epithelium functions as a dynamic barrier that serves as an interface between luminal contents and underlying tissue compartments, and is thus vital in maintaining mucosal homeostasis. Mucosal wounds have been observed following enteric infection, inflammatory bowel disease and ischemic insults. Disruption of the critical epithelial barrier allows access of luminal contents to immunologically privileged compartments thereby contributing to disease pathogenesis. In response to injury, intestinal epithelial cells (IEC) migrate and proliferate to rapidly cover denuded surfaces and re-establish the epithelia barrier. We have recently identified expression of the N-formyl peptide receptors (FPR1 and FPR2) in the intestinal epithelium. Our studies determined that a bacterial derived N-formyl peptide, fMLF and the endogenous Annexin 1 protein, which are agonists for FPR family members, promote intestinal epithelial cell migration and facilitate wound closure. Additionally, it is becoming evident that a healthy optimized intestinal microflora mediates important roles in normal gut homeostasis and recovery from mucosal insults. Recent experimental results in our laboratory revealed that epithelial cells exposed to fMLF and intact bacteria also rapidly initiate cytoplasmic signaling events, Rac and Cdc2 activation, reactive oxygen species (ROS) production, epithelial cell migration and wound closure. Thus, we believe that FPRs represent important novel type of pattern recognition receptors (PRR) in the intestinal epithelium that transmit homeostatic signaling and facilitate epithelial barrier recovery following pathologic insults. Thus, our overall objectives are to define the pathobiologic function of epithelial FPRs and microbiota in regulating intestinal homeostasis, barrier recovery and resolution of inflammation.