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Dietary L-Tryptophan Consumption Determines The Number Of Colonic Regulatory T Cells And Susceptibility To Colitis Via Gpr15, Nguyen Van, Karen Zhang, Rachel Wigmore, Anne Kennedy, Carolina Dasilva, Jialing Huang, Manju Ambelil, Jose Villagomez, Gerald O'Connor, Randy Longman, Miao Cao, Adam Snook, Michael Platten, Gerard Kasenty, Luis Sigal, George C Prendergast, Sangwon Kim

Department of Microbiology and Immunology Faculty Papers

Environmental factors are the major contributor to the onset of immunological disorders such as ulcerative colitis. However, their identities remain unclear. Here, we discover that the amount of consumed L-Tryptophan (L-Trp), a ubiquitous dietary component, determines the transcription level of the colonic T cell homing receptor, GPR15, hence affecting the number of colonic FOXP3⁺ regulatory T (Treg) cells and local immune homeostasis. Ingested L-Trp is converted by host IDO1/2 enzymes, but not by gut microbiota, to compounds that induce GPR15 transcription preferentially in Treg cells via the aryl hydrocarbon receptor. Consequently, two weeks of dietary L-Trp supplementation nearly double …