Anti-commensal IgG Drives Intestinal Inflammation and Type 17 Immunity in Ulcerative Colitis.

ABSTRACT: Inflammatory bowel disease is a chronic, relapsing condition with two subtypes, Crohn's disease (CD) and ulcerative colitis (UC). Genome-wide association studies (GWASs) in UC implicate a FCGR2A variant that alters the binding affinity of the antibody receptor it encodes, Fc?RIIA, for immunoglobulin G (IgG). Here, we aimed to understand the mechanisms whereby changes in Fc?RIIA affinity would affect inflammation in an IgA-dominated organ. We found a profound induction of anti-commensal IgG and a concomitant increase in activating Fc?R signaling in the colonic mucosa of UC patients. Commensal-IgG immune complexes engaged gut-resident Fc?R-expressing macrophages, inducing NLRP3- and reactive-oxygen-species-dependent production of interleukin-1? (IL-1?) and neutrophil-recruiting chemokines. These responses were modulated by the FCGR2A genotype. In vivo manipulation of macrophage Fc?R signal strength in a mouse model of UC determined the magnitude of intestinal inflammation and IL-1?-dependent type 17 immunity. The identification of an important contribution of IgG-Fc?R-dependent inflammation to UC has therapeutic implications.

SUBMITTER: Castro-Dopico T 

PROVIDER: S-EPMC6477154 | biostudies-literature | 2019 Apr

REPOSITORIES: biostudies-literature