Activation of aryl hydrocarbon receptor alleviates cholestatic liver injury by inhibiting inflammation

Cholestatic liver injury (CLI) is a severe liver disorder caused by impaired bile flow, for which effective therapeutic options remain limited. Although the aryl hydrocarbon receptor (AHR) has been implicated in protection against CLI, the mechanisms underlying its dysregulation and functional role during cholestasis remain incompletely understood. Here, we investigated the role of AHR in cholestatic liver injury and the mechanisms contributing to impaired AHR activation using multi-omics approaches. Using mouse models of CLI induced by a 0.1% 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) diet or bile duct ligation (BDL), we found that tryptophan metabolism and AHR signaling were markedly disrupted during cholestasis. Pharmacological activation of AHR with the tryptophan-derived agonist (1′H-indole-3′-carbonyl)-thiazole-4-carboxylic acid methyl ester (ITE), as well as AAV-mediated AHR overexpression, significantly attenuated liver injury, as evidenced by reduced body weight loss, decreased porphyrin deposition, and diminished infiltration of macrophages and neutrophils. Transcriptomic analysis revealed that ITE treatment suppressed chemokine and inflammatory gene expression. Mechanistically, activated AHR bound to the CCL2 promoter and repressed its transcription, which was associated with reduced recruitment of inflammatory cells. Integrated metabolomic and 16 S rDNA sequencing analyses further demonstrated that cholestasis was associated with altered tryptophan-metabolizing gut microbiota and reduced availability of endogenous AHR ligands, correlating with impaired AHR activation and aggravated liver injury. Collectively, these findings indicate that restoration of AHR activity by tryptophan-derived metabolites or AAV-mediated AHR overexpression alleviates inflammation and ameliorates cholestatic liver injury, highlighting AHR signaling as a potential therapeutic target in cholestasis associated with disordered tryptophan metabolism.