Aryl Hydrocarbon Receptor Deficiency in Intestinal Epithelial Cells Aggravates Alcohol-Related Liver Disease

BACKGROUND & AIMS: The ligand-activated transcription factor, aryl hydrocarbon receptor (AHR) can sense xenobiotics, dietary, microbial, and metabolic cues. Roles of Ahr in intestinal epithelial cells (IECs) have been much less elucidated compared with those in intestinal innate immune cells. Here, we explored whether the IEC intrinsic Ahr could modulate the development of alcohol-related liver disease (ALD) via the gut-liver axis. METHODS: Mice with IEC specific Ahr deficiency (Ahr(Delta IEC)) were generated and fed with a control or ethanol diet. Alterations of intestinal microbiota and metabolites were investigated by 16S ribosomal RNA sequencing, metagenomics, and untargeted metabolomics. AHR agonists were used to evaluate the therapeutic potentials of intestinal Ahr activation for ALD treatment. RESULTS: Ahr(Delta IEC) mice showed more severe liver injury after ethanol feeding than control mice. Ahr deficiency in IECs altered the intestinal metabolite composition, creating an environment that promoted the overgrowth of Helicobacter hepaticus and Helicobacter ganmani in the gut, enhancing their translocation to mesenteric lymph nodes and liver. Among the altered metabolites, isobutyric acid was increased in the cecum of ethanol-fed Ahr(Delta IEC) mice relative to control mice. Furthermore, both H. hepaticus and isobutyric acid administration aggravated ethanol-induced liver injury in vivo and in vitro. Supplementation with AHR agonists, 6-formylindolo[3,2-b] carbazole and indole-3-carbinol, protected mice from ALD development by specifically activating intestinal Ahr without affecting liver Ahr function. Alcoholic patients showed lower intestinal AHR expression and higher H. hepaticus levels compared with healthy individuals.

Automated summary

The intrinsic AHR in intestinal epithelial cells (IECs) plays a role in the development of alcohol-related liver disease (ALD) by modulating the intestinal microbiota and metabolite composition. AHR deficiency in IECs leads to the overgrowth of Helicobacter spp. in the gut, promoting their translocation to lymph nodes and liver and worsening liver injury. Isobutyric acid, an altered metabolite in Ahr(Delta IEC) mice, along with Helicobacter spp., exacerbates ethanol-induced liver injury. Activation of intestinal AHR with specific agonists protects mice from ALD development. Alcoholic patients have lower intestinal AHR expression and higher levels of Helicobacter spp.