A conserved Bacteroidetes antigen induces anti-inflammatory intestinal T lymphocytes
Djenet Bousbaine, Laura Fisch, Mariya London, Preksha Bhagchandani, Tiago B. R. Castro, Mark Mimee, Scott W. Olesen, Bernardo Sgarbi Reis, David VanInsberghe, Juliana Bortolatto, Mathilde Poyet, Ross W. Cheloha, John Sidney, Jingjing Ling, Aaron Gupta, Timothy K. Lu, Alessandro Sette, Eric J. Alm, James J. Moon, Gabriel D. Victora, Daniel Mucida, Hidde L. Ploegh, Angelina M. Bilate
Abstract
The microbiome contributes to the development and maturation of the immune system. In response to commensal bacteria, intestinal CD4 + T lymphocytes differentiate into functional subtypes with regulatory or effector functions. The development of small intestine intraepithelial lymphocytes that coexpress CD4 and CD8αα homodimers (CD4IELs) depends on the microbiota. However, the identity of the microbial antigens recognized by CD4 + T cells that can differentiate into CD4IELs remains unknown. We identified β-hexosaminidase, a conserved enzyme across commensals of the Bacteroidetes phylum, as a driver of CD4IEL differentiation. In a mouse model of colitis, β-hexosaminidase–specific lymphocytes protected against intestinal inflammation. Thus, T cells of a single specificity can recognize a variety of abundant commensals and elicit a regulatory immune response at the intestinal mucosa.