mAChR4 suppresses liver disease via GAP-induced antimicrobial immunity

Alcohol-use disorder and alcohol-associated liver disease (ALD) are major causes of death and liver transplantation¹. The gut-liver axis has a crucial yet poorly understood role in ALD pathogenesis, which depends on microbial translocation. Intestinal goblet cells (GCs) educate the immune system by forming GC-associated antigen passages (GAPs) on activation of muscarinic acetylcholine receptor M4 (mAChR4, also known as M₄), enabling sampling of luminal antigens by lamina propria antigen-presenting cells. Here we show that chronic alcohol use in humans and mice downregulates small intestinal mAChR4 and reduces GAP formation, disrupting antimicrobial immunity. This is reversed on activation of intestinal IL-6 signal transducer (IL6ST, also known as glycoprotein 130; gp130), which restores mAChR4 expression and GAP formation, enabling induction of downstream type-3 innate lymphoid cell-derived IL-22 and antimicrobial REG3 proteins. This blunts translocation of enteric bacteria to the liver, thereby conferring ALD resistance. GAP induction by GC-specific mAChR4 activation was essential and sufficient for prevention of ethanol-induced steatohepatitis. These results lay the foundation for a therapeutic approach using mAChR4 or IL6ST agonists to promote GAP formation and prevent ALD by inhibiting microbial translocation.