Immunometabolic Mechanisms of Protection against Infection

Nimml Institute, Inc., Blacksburg VA

Investigators

Abstract

Immunometabolic Mechanisms of Protection against Infection The NIMML Institute is a 501 (c) (3) non-profit public foundation focused on a transdisciplinary, team-science approach to precision medicine at the interface of immunology, inflammation, and metabolism. We are pioneering fundamental research on novel immunometabolic mechanisms that control disease severity and treatment outcomes in infectious and autoimmune diseases. Clostridioides difficile is a spore-forming, toxin producing, anerobic, gram-positive bacterium that causes nosocomial infectious colitis affecting almost half a million people only in the U.S. yearly. There is an unmet clinical need for the development of antimicrobial-free, host-centered therapeutics with increased efficacy to treat C. difficile infection (CDI). C. difficile toxins are the main virulence factors of C.difficile. Immunometabolic mechanisms are implicated in modulating signaling pathways and endosomal transport within the cell. During CDI, upon endocytosis and pH-dependent translocation to the cytosol, activated TcdA and TcdB glucosylate and inactivate Rho GTPases. Preliminary findings demonstrate that cytopathic effects, including inflammasome activation, cell death, and impaired barrier function, are significantly suppressed by activation of novel immunometabolic pathways during intoxication. This R21 aims to elucidate novel immunometabolic mechanisms that intercept bacterial toxin internalization and processing to suppress cell damage. The specific Aims are: AIM 1. To elucidate novel immunometabolic mechanisms that interfere with TcdA and TcdB glucosylation of RhoA and Rac1 in colonic epithelial cells. We will use human intestinal organoids to investigate whether immunometabolic pathways suppress glucosylation of Rho family proteins. We will link the degree of glucosylation to induced cytopathic effects and their modulation through activation of immunometabolic intervention. AIM 2. To determine the role of a novel immunometabolic pathway in regulating endosomal pH and toxin translocation in colonic epithelial cells: using colon-derived organoids, we will evaluate changes in endosomal pH, V-ATPase activity and cellular sublocalization, and downstream signaling in response to immunometabolic pathway activation. This R21 grant application will investigate a novel immunometabolic mechanism that modulates the outcome of bacterial intoxication. The results from these studies will provide the novel mechanistic insights to guide the development of new host-based therapies targeting a new mechanism of action to treat CDI and other toxin- producing bacteria.