Disturbed lipid metabolism precedes alcoholic liver injury. Whether and how AhR alters degradation of lipids, particularly phospho-/sphingo-lipids during alcohol exposure, was not explored. Here, we show that alcohol consumption in mice results in induction and activation of aryl hydrocarbon receptor (AhR) in the liver, and changes the hepatic phospho-/sphingo-lipids content. The levels of kynurenine, an endogenous AhR ligand, are elevated with increased hepatic tryptophan metabolic enzymes in alcohol-fed mice. Either alcohol or kynurenine treatment promotes AhR activation with autophagy dysregulation via AMPK. Protein Phosphatase 2 Regulatory Subunit-Bdelta (Ppp2r2d) is identified as a transcriptional target of AhR. Consequently, PPP2R2D-dependent AMPKα dephosphorylation causes autophagy inhibition and mitochondrial dysfunction. Hepatocyte-specific AhR ablation attenuates steatosis, which is associated with recovery of phospho-/sphingo-lipids content. Changes of AhR targets are corroborated using patient specimens. Overall, AhR induction by alcohol inhibits autophagy in hepatocytes through AMPKα, which is mediated by Ppp2r2d gene transactivation, revealing an AhR-dependent metabolism of phospho-/sphingo-lipids.

Arnica montana (AM), which belongs to the daisy family Asteraceae, has a longstanding traditional use in Europe and North America for pain and inflammation treatment. This study investigates the inhibitory effects of ‘Arnica montana extract hydrogel patch (AHP)’ on Carrageenan-induced paw edema and hot plate-induced pain models. AHP exhibited transdermal permeability without the occurrence of issues like crystal precipitation. This study employed two animal model assessments using AHP, in comparison with Arnicare Gel (AG), to evaluate anti-inflammatory and pain relief effects. AHP treatment for 2 days showed a decrease in paw edema thickness in mice as compared to vehicle or AG groups; Carrageenan-induced swelling increased maximally at 1 h with the AHP group demonstrating a higher reduction. Thus, the AHP group exhibited a lower ratio of right/left paw thickness and a superior reduction in swelling, supportive of its ability to diminish edema. A histological analysis showed that AHP treatment reduced inflammatory cell infiltration. Consistently, the mRNA levels of inflammatory markers (tnfa, il1b, and il6) were decreased to a greater extent than the AG group. Particularly, tnfa inhibition was better in the AHP group, and the levels of il1b and il6 transcripts showed ~80% and 40% lower. Likewise, AHP reduced pain scores in a hot plate-induced rat model, although AG failed to do so. Together, these results demonstrate that AHP has long-lasting inhibitory effects on fluid effusion and edema formation, the production of inflammatory mediators, and pain-sensation, supporting its anti-inflammatory and pain-relieving pharmacological effects.

Fasiglifam, a candidate targeting GPR40, showed efficacy in clinical trials for type 2 diabetes but exerted liver toxicity. This study investigated the drug-induced liver injury (DILI) risk of Xelaglifam, a new GPR40 agonist, based on the potential toxicity mechanism of Fasiglifam; transporter inhibition, mitochondrial dysfunction, reactive metabolite formation, and covalent binding to proteins. In the hepatobiliary transporter assay, Xelaglifam showed a broader safety margin (>10-fold) against bile acid transporters, suggesting its less likelihood to cause bile acids accumulation, unlike Fasiglifam (<10-fold safety margin). Moreover, Xelaglifam showed no effect on glycocholic acid accumulation at higher concentrations than the estimated C_max in the 3D human liver model, whereas Fasiglifam affected the accumulation. In the HepaRG spheroids 3D model, the AC₅₀ values of Xelaglifam for mitochondrial function-related parameters were higher than Fasiglifam. Unlike Fasiglifam, none of the cell parameters for Xelaglifam were below the estimated 5x C_max. Additionally, the glucuronide metabolite of Xelaglifam was negligible (<1 % of the parent) in the Safety Testing, indicating a limited contribution to DILI. Fasiglifam activated genes related to liver disease, whereas Xelaglifam had no effect; instead, it increased FXR activity, a bile acid regulator. Notably, toxicity studies in rats and monkeys showed no adverse liver effects at higher exposure levels than the effective human blood concentration. Overall, these results support a low risk of DILI for Xelaglifam treatment and the justification for its long-term use for treating type 2 diabetes.