Discovery of 4-aminophenylacetamide derivatives as intestine-specific farnesoid X receptor antagonists for the potential treatment of nonalcoholic steatohepatitis

Ileal FXR Knockdown Ameliorates MASLD Progression in Rats via Modulating Bile Acid Metabolism Mediated by Gut Microbiota

BACKGROUND AND AIM

Metabolic dysfunction associated steatotic liver disease (MASLD) is the predominant cause of chronic liver disease, with dysregulation of bile acid (BA) metabolism and intestinal microbiota being intricately associated with MASLD progression. In this study, we investigated the role of ileal FXR in MASLD progression and BA metabolism in portal blood.

METHODS

Sprague-Dawley rats were fed a typical western diet for 20 weeks, followed by local perfusion of AAV2-shNr1h4 to downregulate Nr1h4 expression in ileum tissue. To investigate the effect of ileal FXR on BA reabsorption and gut microbiota, portal blood and cecal fecal samples were collected from MASLD rats injected with AAV2-Ctrl or AAV2-shNr1h4 for metabolomics targeting BAs and 16S rRNA sequencing analysis.

RESULTS

Our results showed that hepatic steatosis and inflammation were alleviated, whereas the reabsorption of secondary BAs and unconjugated BAs into the portal blood was enhanced when ileal FXR was knocked down. Furthermore, knockdown of ileal FXR resulted in a significant alteration in composition of the cecal microbiota, characterized by an increasing abundance of microbes involved in secondary BA production, including Escherichia, Adlercreutzia, Eubacterium, and Clostridium.

CONCLUSION

These findings suggest that downregulation of ileal FXR ameliorates the progression of MASLD in rats by modulating BA metabolism mediated by the gut microbiota, indicating that ileal FXR might be a potential therapeutic target for the treatment of MASLD.

Design, synthesis and FXR partial agonistic activity of anthranilic acid derivatives bearing aryloxy moiety as therapeutic agents for metabolic dysfunction-associated steatohepatitis

Farnesoid X receptor (FXR) is considered a promising therapeutic target for the treatment of metabolic dysfunction-associated steatohepatitis (MASH). Increasing evidence suggests that targeting FXR with full agonists may lead to side effects. FXR partial agonists, which moderately activate FXR signaling, are emerging as a feasible approach to mitigate side effects and address MASH. Herein, a series of novel anthranilic acid derivatives bearing aryloxy moiety were designed and synthesized using a hybrid strategy from the previously identified FXR partial agonists DM175 and AIV-25. Particularly, compound 26 exhibited potent FXR partial agonistic activity in a dual-luciferase reporter gene assay with an EC50 value of 0.09 ± 0.02 µM (75.13 % maximum efficacy relative to OCA). In the MASH mice model, compound 26 significantly ameliorated the pathological features of the liver, including steatosis, inflammation, and fibrosis. In addition, compound 26 displayed high selectivity, good oral bioavailability, high liver distribution, as well as an acceptable safety profile. Molecular simulation studies showed that compound 26 fitted well with the binding site of FXR. Collectively, these findings demonstrated that compound 26 might serve as a promising candidate targeting FXR for MASH treatment.

A Current Understanding of FXR in NAFLD: The multifaceted regulatory role of FXR and novel lead discovery for drug development

The global prevalence of nonalcoholic fatty liver disease (NAFLD) has reached 30 %, with an annual increase. The incidence of NAFLD-induced cirrhosis is rapidly rising and has become the leading indicator for liver transplantation in the US. However, there are currently no US Food and Drug Administration-approved drugs for NAFLD. Increasing evidence underscores the close association between NAFLD and bile acid metabolism disorder, highlighting the feasibility of targeting the bile acid signaling pathway for NAFLD treatment. The farnesoid X receptor (FXR) is an endogenous receptor for bile acids that exhibits favorable effects in ameliorating the metabolic imbalance of bile acids, lipid disorders, and disruption of intestinal homeostasis, all of which are key characteristics of NAFLD, making FXR a promising therapeutic target for NAFLD. The present review provides a comprehensive overview of the diverse mechanisms through which FXR improves NAFLD, with particular emphasis on its involvement in regulating bile acid homeostasis and the recent advancements in drug development targeting FXR for NAFLD treatment.

Bile acid metabolism and signaling in health and disease: molecular mechanisms and therapeutic targets

Bile acids, once considered mere dietary surfactants, now emerge as critical modulators of macronutrient (lipid, carbohydrate, protein) metabolism and the systemic pro-inflammatory/anti-inflammatory balance. Bile acid metabolism and signaling pathways play a crucial role in protecting against, or if aberrant, inducing cardiometabolic, inflammatory, and neoplastic conditions, strongly influencing health and disease. No curative treatment exists for any bile acid influenced disease, while the most promising and well-developed bile acid therapeutic was recently rejected by the FDA. Here, we provide a bottom-up approach on bile acids, mechanistically explaining their biochemistry, physiology, and pharmacology at canonical and non-canonical receptors. Using this mechanistic model of bile acids, we explain how abnormal bile acid physiology drives disease pathogenesis, emphasizing how ceramide synthesis may serve as a unifying pathogenic feature for cardiometabolic diseases. We provide an in-depth summary on pre-existing bile acid receptor modulators, explain their shortcomings, and propose solutions for how they may be remedied. Lastly, we rationalize novel targets for further translational drug discovery and provide future perspectives. Rather than dismissing bile acid therapeutics due to recent setbacks, we believe that there is immense clinical potential and a high likelihood for the future success of bile acid therapeutics.

FXR Antagonist FLG249 Lowers Hepatic Triacylglycerol and Serum Cholesterol Level in High-Fat Diet-Induced Obese Mice

Farnesoid X receptor (FXR) is a nuclear receptor that regulates the synthesis and enterohepatic circulation of bile acids (BAs). It also regulates lipid and carbohydrate metabolism, making FXR ligands potential therapeutic agents for systemic and/or hepatic metabolic disorders. We previously synthesized a series of FXR antagonists and showed that oral administration of FLG249 reduced the expression of several FXR target genes in the mouse ileum. Here, we investigated the effects of FLG249 on lipid metabolism in mice fed a high-fat diet (HFD). When FLG249 was administered for 4 weeks to HFD-induced obese mice, it altered the expression of genes related to BA metabolism, ceramide synthesis and fatty acid β-oxidation, improving lipid metabolism in the liver and ileum without decreasing body weight. These findings suggest that FLG249 has the potential to be a low toxicity pharmaceutical compound and likely acts as a nonsteroidal FXR antagonist to improve lipid metabolism disorders.