Aggravated gut inflammation in mice lacking the taste signaling protein alpha-gustducin

Inflammatory bowel disease (IBD) is a debilitating immune-related condition that affects over 1.4 million Americans. Recent studies indicate that taste receptor signaling is involved in much more than sensing food flavor, and taste receptors have been localized in a variety of extra-oral tissues. One of the newly revealed functions of taste receptors and downstream signaling proteins is modulation of immune responses to microbes and parasites. We previously found that components of the taste receptor signaling pathway are expressed in subsets of the intestinal epithelial cells. alpha-Gustducin, a key G-protein a subunit involved in sweet, umami, and bitter taste receptor signaling, is expressed in the intestinal mucosa. In this study, we investigated the role of alpha-gustducin in regulation of gut mucosal immunity and inflammation using alpha-gustducin knockout mice in the dextran sulfate sodium (DSS)-induced IBD model. DSS is a chemical colitogen that can cause intestinal epithelial damage and inflammation. We analyzed DSS-induced colitis in alpha-gustducin knockout versus wild-type control mice after administration of DSS in drinking water. Our results show that the knockout mice had aggravated weight loss, diarrhea, intestinal bleeding, and inflammation over the experimental period compared to wild-type mice, concurrent with augmented immune cell infiltration and increased expression of TNF and IFN-gamma but decreased expression of IL-13 and IL-5 in the colon. These results suggest that the taste receptor signaling pathway may play critical roles in regulating gut immune balance and inflammation.