First-in-class small molecule therapeutics to enhance gut barrier function in inflammatory bowel disease PA-20-260, R43 Phase I SBIR PI: Frederick M. Ausubel Project Summary Inflammatory Bowel Disease (IBD), which affects approximately to 3 million Americans, is characterized by chronic relapsing inflammation and barrier dysfunction, manifested as enhanced permeability of the intestinal epithelium caused by a breakdown of tight junction proteins between cells. Because FDA-approved IBD therapeutics target inflammation rather than barrier dysfunction, there is a current need for an orally available, non-toxic, non-immunosuppressive IBD therapeutic that directly enhances barrier function and blocks progression to more severe forms of IBD. Artus Therapeutics is developing IBD therapeutics inspired by the natural microbiome compound urolithin A (UroA). UroA exhibits anti-inflammatory activity and a highly favorable toxicity profile in rodents and humans, but its lack of stability at low pH is a major impediment for its further development. Artus therapeutics has synthesized a urolithin analog, ARTX-2, that is significantly more acid stable and more resistant to hydrolysis by digestive enzymes than UroA. Published and preliminary data show that oral administration of ARTX-2 dramatically mitigates the symptoms of dextran sodium sulphate (DSS) or 2,4,6-Trinitrobenzenesulfonic acid (TNBS) induced ulcerative colitis in mice. Further, ARTX-2 up-regulates tight junction proteins (TJPs) including Claudin4 and Occludin in gut epithelium as well as blocks LPS-induced inflammatory cytokines in bone marrow derived macrophages (BMDMs). Genetic analysis in mice shows that the bioactivity of ARTX-2 is dependent upon the aryl hydrocarbon receptor (AhR) and the nuclear transcription factor (erythroid-derived 2)-like 2 (Nrf2). Based on these observations, it was concluded ARTX-2 mitigates IBD through activation of AhR-dependent pathways at two distinct levels: by (i) preserving and/or enhancing gut barrier function and (ii) reducing systemic and acute inflammation by downregulating inflammatory cytokines in immune cells. Based on the promising data with ARTX-2, 44 more ARTX-2 analogs have been synthesized and preliminary data show that some of these analogs appear to be more potent than ARTX-2 in blocking the production of inflammatory cytokines in BMDMs. In this SBIR Phase I application, we propose lead optimization of ARTX-2. In Aim 1, we will compare ARTX-2 and 44 ARTX-2 analogs with respect to: 1) upregulation of TJPs: 2) decrease in epithelial permeability; and 3) downregulation of cytokines. Up to 10 analogs that are equally or more potent than ARTX-2 will be further tested for their efficacy in dose-response assays. In Aim 2, we will carry out efficacy studies in the mouse TNBS chemically-induced model of ulcerative coliits for the top 5 prioritized compounds from Aim 1. For the 3 most efficacious compounds in the mouse TNBS model, we will further test for effi...