Parallel regulation of goblet cell–associated antigen passages by reduced microbial sensing and mAChR4 signaling in Muc2 deficiency prevents ethanol-induced liver injury

BACKGROUND AND AIMS: Alcohol-associated liver disease (ALD) is linked to intestinal barrier dysfunction, allowing microbial translocation that drives liver inflammation. The role of goblet cells (GCs) in maintaining intestinal homeostasis and regulating ALD has only recently been explored. Notably, the absence of mucin 2 (Muc2), the major secreted intestinal mucin, is protective against ALD, and GC-associated antigen passages (GAPs), gateway-like structures mediating antimicrobial immunity, play a critical role in prevention. We previously showed that intestinal epithelial gp130 signaling promotes duodenal GAP formation through activation of muscarinic acetylcholine receptor 4 (mAChR4), thereby protecting against ethanol-induced liver injury. Here, we aimed to define the contributions of Muc2 deficiency and mAChR4-formed GAPs to ALD prevention. APPROACH AND RESULTS: Duodenal transcriptomics from patients with alcohol use disorder revealed upregulation of GC-related genes involved in mucin glycosylation and secretion, while CHRM4 (encoding mAChR4 ) inversely correlated with mucin glycosylation, linking mucin dynamics to GAP formation. Consistently, Muc2 deficiency in mice promoted duodenal GAPs through reduced Myd88 expression and conferred protection against ethanol-induced liver injury. However, genetically induced GAP closure in Muc2-/- mice abolished protection, indicating mucin loss alone is insufficient. GC-specific mAChR4 deletion reduced GAPs, impaired intestinal immunity, increased bacterial translocation, and worsened steatohepatitis. Conversely, pharmacologic activation with an mAChR4-positive allosteric modulator restored GAPs, enhanced antimicrobial defense, and prevented liver injury. CONCLUSIONS: GAPs are central to gut-liver homeostasis. Muc2 deficiency enhances GAP formation and confers protection against ALD, whereas GAP closure exacerbates disease. Targeting GC-specific mAChR4 to restore GAPs represents a promising therapeutic strategy for ALD.