Neuronal cells co-ordinate myeloid-epithelial cell interaction to regulate intestinal inflammation

Epithelial response to injury is coordinated through an intricate interaction with neuronal and myeloid cells, however the signaling modules involved are not well understood. In humans, somatic mutations in Tet methylcytosine dioxygenase 2 (TET2), a DNA demethylase, are commonly observed during ageing in myeloid cells and known to modulate inflammatory responses. Using a mouse model that lacks TET2 in myeloid cells (Tet2 ΔLysM), we show that myeloid cells and sympathetic neurons form a signaling nexus that controls differentiation of enterochromaffin cells and serotonin production during colonic inflammation. Under physiological conditions, TET2 restricts IL-1β production by myeloid cells which in turn controls the intestinal sympathetic architecture. During inflammation, IL1R signaling limits sympathetic cues that drive differentiation of enterochromaffin cells through α1-adrenergic signaling. As a result, enterochromaffin differentiation and colitis progression in response to mucosal injury is attenuated in Tet2 ΔLysMmice. Further, protection from colitis in Tet2 ΔLysMmice is mediated by its catalytic activity, and dependent on sympathetic neurons and IL1R signaling. Adrenergic control of epithelial response and pro-colitic serotonin production is also evident under conditions of physiological stress that leads to increased colitis susceptibility. Overall, our study reveals a sympathetic-epithelial axis that controls the severity of colitis and is modulated by myeloid-derived IL-1β and physiological stress. Our findings may also explain why inflammatory bowel disease in the elderly, where TET2 mutations in myeloid cells are common, is less severe and suggests TET2 activity as an attractive target for IBD. Supported by the US National Institutes of Health (DK067180) to B.J, the University of Chicago's Center for Interdisciplinary Study of Inflammatory Intestinal Disorders (C-IID) Pilot & Feasibility Award (NIDDK P30 DK042086) to A.M. and D.S, Crohn’s and Colitis Foundation Career Development Award #964209 to A.M. and G.I. Research Foundation Associates Board Award to A.M. and D.S.