A20’s Linear Ubiquitin Binding Motif Restrains Pathogenic Activation of TH17/22 cells and IL-22 Driven Enteritis [scRNA-seq]

A20, encoded by the TNFAIP3 gene, is a protein linked to Crohn and celiac disease in humans. We show that mice expressing point mutations in A20’s M1-ubiquitin binding zinc-finger 7 (ZF7) domain spontaneously develop proximal enteritis that requires both luminal microbes and T cells. Cellular and transcriptomic profiling reveal expansion of TH17/22 cells and exuberant expression of IL-17A and IL-22 in intestinal lamina propria of A20ZF7 mice. While deletion of IL-17A from A20ZF7 mice exacerbates enteritis, deletion of IL-22 abrogates intestinal epithelial cell hyperproliferation, barrier dysfunction, and alarmin expression. Colonization of adult germ-free mice with normal luminal flora drives duodenal IL-22 expression and duodenitis. A20ZF7 TH17/22 cells autonomously express more RORgammat and IL-22 after differentiation in vitro. ATAC sequencing identified an enhancer region upstream of the Il22 gene, and this enhancer demonstrated increased activating histone acetylation coupled with exaggerated Il22 transcription in A20ZF7 T cells. Acute inhibition of RORgammat normalized histone acetylation at this enhancer. Finally, CRISPR/Cas9-mediated ablation of A20ZF7 in human T cells increases RORgammat expression and IL22 transcription. These studies link A20’s M1-ubiquitin binding function with RORgammat expression, expansion of TH17/22 cells, and epigenetic activation of IL-22 driven enteritis.