Title: Identification of anti-inflammatory pathways induced by enterotoxin B subunits for use as therapeutics in inflammatory bowel disease

Program: Biomolecular Sciences MS

Committee Chair: Juliette Tinker

Committee Co-Chair: Javier Ochoa-Reparaz

Committee: Juliette Tinker, Javier Ochoa-Reparaz, Henry Charlier

Abstract: Vibrio cholerae’s AB5 enterotoxin, cholera toxin (CT), has a homopentameric, non-toxic B subunit (CTB). CTB is a well-known vaccine adjuvant used for its ability to create a strong immune response, however more recent studies have shown its ability to also behave in an anti-inflammatory manner, performing as a protective agent in a variety of different inflammatory diseases. Escherichia coli (E. coli) produces a heat-labile AB5 enterotoxin (LT) that is very homologous to CT, with its B subunit (LTB) being used in a similar manner as a vaccine adjuvant. There have been many studies comparing LTB to CTB due to their similar structures and properties, however research is lacking on whether LTB shares CTB’s anti-inflammatory characteristics.

Inflammatory Bowel Diseases (IBD) like Crohn’s and ulcerative colitis are chronic illnesses caused by inflammation in the intestines. These diseases affect millions of people world-wide with billions of dollars in health care costs, yet treatment options are extremely limited. CTB’s anti-inflammatory properties and ability to promote mucosal tissue healing makes it a potential treatment option for IBD. To better understand the pathogenesis of inflammatory bowel diseases and analyze drug candidates, reliable preclinical animal models are essential. In mice, 2,4,6 - trinitrobenzene sulfonic acid, or TNBS, can be used as a hapten reagent with ethanol to chemically induce ulcerative colitis.

The long-term goal of these studies is to develop effective IBD treatments that can reduce or eliminate inflammation. I hypothesized that CTB and LTB treatment of epithelial cells would reduce inflammatory pathways, and that the efficacy of these proteins could be tested in a preclinical mouse model of disease. While these molecules were not ultimately assessed in vivo, the mouse model was verified, and anti-inflammatory pathways induced by CTB and LTB were identified by RNAseq in vitro. The outcomes of these studies were: 1) to help test a repeatable and consistent TNBS mouse model to assess potential IBD treatments, 2) to identify and compare immune signals induced by bacterial enterotoxin B subunits from epithelial cells. These studies will help to determine the anti-inflammatory mechanism of CTB and LTB to support its use in the future as a treatment for IBD.