Inflammatory Bowel Diseases (IBDs), which include f ulcerative colitis and Crohn?s disease, affect as many as 1.4 million people in the USA. Chronic inflammation and microbial dysbiosis are major features of IBDs. Beneficial effects rendered by healthy dietary practices are not uniform among individuals and are attributed to variations in gut microbiota and their active metabolites. To overcome the challenge of inter-individual differences in gut microbiota, their metabolites and poor bioavailability, here we propose direct usage of microbial metabolites to maintain gut immune homeostasis to mitigate IBDs. Urolithin A (UroA) is one of such beneficial microbial metabolite derived from ellagic acid and ellagitannins, major polyphenolic components of berries and pomegranate. Based on UroA structure, we developed novel potent structural analogue, UAS03, which exhibited increased anti-inflammatory and gut barrier functional activities compared to parent UroA compound. The current proposal investigates the molecular and cellular mechanisms of UAS03 and its therapeutic efficacies in IBD pre-clinical models. Our preliminary results showed that the oral administration of UAS03 mitigated colitis in dextran sodium sulphate (DSS)- or 2,4,6-Trinitrobenzenesulfonic acid (TNBS) induced murine colitis even at 10 fold lower dose compared to UroA. UAS03 significantly inhibited lipopolysaccharide (LPS)-induced increase in inflammatory mediators in immune cells and epithelial cells with 10 fold higher efficacy than UroA. Further, treatment with UAS03 reduced intestinal permeability by up-regulating junctional proteins through activation of nuclear factor (erythroid-derived 2)-like 2 (Nrf2)-hemoxygenase (HO1) pathways in epithelial cells. Based on these results, we propose two-pronged beneficial activities of UAS03 and UroA, where these compounds protect the host from external challenges by protecting gut barrier function and dampening inflammatory activities. In this proposal we will test the hypothesis that ?treatment with UAS03, an effective analogue of a microbial metabolite, protects from IBD development by reducing barrier dysfunction and inflammation.
In Aim 1, we will investigate how USA03/UroA increase gut barrier function in a Nrf2-dependent manner by upregulating junctional proteins as well as molecular events involved anti-inflammatory activities of UAS03.
In Aim 2, therapeutic efficacies of UAS03 and UroA will be examined in acute, chronic and spontaneous IBD pre-clinical models.
In Aim 3, we propose to identify the bacteria responsible for UroA production and test their pro-biotic activities in colitis models. The successful completion of proposed studies will allow understanding of UAS03 and UroA mechanisms of actions, and establishes the basis for therapeutic usage in IBDs.