title: Tryptophan: A gut microbiota-derived metabolites regulating inflammation.
abstract: Inflammatory bowel diseases (IBD), which comprise Crohn's disease and ulcerative colitis, are chronic intestinal disorders with an increased prevalence and incidence over the last decade in many different regions over the world. The etiology of IBD is still not well defined, but evidence suggest that it results from perturbation of the homeostasis between the intestinal microbiota and the mucosal immune system, with the involvement of both genetic and environmental factors. Genome wide association studies, which involve large-scale genome-wide screening of potential polymorphism, have identified several mutations associated with IBD. Among them,Card9, a gene encoding an adapter molecule involved in innate immune response to fungi (viatype C-lectin sensing) through the activation of IL-22 signaling pathway, has been identified as one IBD susceptible genes. Dietary compounds, which represent a source of energy and metabolites for gut bacteria, are also appreciated to be important actors in the etiology of IBD, for example by altering gut microbiota composition and by regulating the generation of short chain fatty acids. A noteworthy study published in the June 2016 issue ofNature Medicineby Lamas and colleagues investigates the interaction betweenCard9and the gut microbiota in the generation of the microbiota-derived tryptophan metabolite. This study highlights the role of tryptophan in dampening intestinal inflammation in susceptible hosts.
authors.affiliation: Lucie Etienne-Mesmin, Benoit Chassaing, Andrew T Gewirtz, Center for Inflammation, Immunity, and Infection, Institute for Biomedical Sciences, Georgia State University, Atlanta, GA 30303, United States.
authors.forename: Lucie
authors.initials: L
authors.lastname: Etienne-Mesmin
authors.affiliation: Lucie Etienne-Mesmin, Benoit Chassaing, Andrew T Gewirtz, Center for Inflammation, Immunity, and Infection, Institute for Biomedical Sciences, Georgia State University, Atlanta, GA 30303, United States.
authors.forename: Benoit
authors.initials: B
authors.lastname: Chassaing
authors.affiliation: Lucie Etienne-Mesmin, Benoit Chassaing, Andrew T Gewirtz, Center for Inflammation, Immunity, and Infection, Institute for Biomedical Sciences, Georgia State University, Atlanta, GA 30303, United States.
authors.forename: Andrew T
authors.initials: AT
authors.lastname: Gewirtz
keywords: Intestinal inflammation; Microbiota; Tryptophan