Transgenic mice lacking FGF15/19-SHP phosphorylation display altered bile acids and gut bacteria, promoting nonalcoholic fatty liver disease

The dichotomous roles of microbial-modified bile acids 7-oxo-DCA and isoDCA in intestinal tumorigenesis

The gut microbiota has a significant impact on the development and function of intestinal epithelial cells (IECs) by modifying bile acid (BA) metabolites. Recently, specific gut microbiome-derived BAs, such as 7-oxo-deoxycholic acid (7-oxo-DCA) and isodeoxycholic acid (isoDCA), have been identified to be shifted inversely in colitis and hepatic liver diseases. Although the responsible gut microbes have been identified, metabolites' effects on IECs remain largely unclear. We found that although high-fat diet treatment in mice elevated both 7-oxo-DCA and isoDCA levels, during intestinal tumorigenesis, 7-oxo-DCA levels rise while isoDCA levels decrease. Interestingly, 7-oxo-DCA promotes cancer cell growth, while isoDCA suppresses it. Moreover, 7-oxo-DCA promotes whereas isoDCA inhibits the proliferation of intestinal stem cells in organoids derived from WT and APCMin/+ mice, as well as in patient-derived colon cancer organoids. The APCMin/+ mice administered with 7-oxo-DCA heightened gut permeability and increased tumor burden, whereas isoDCA protected gut barrier and reduced tumor loads. Both BAs reshape the BA pool and shifted gut microbiome. Mechanistically, we identified 7-oxo-DCA as a natural antagonist of Farnesoid X Receptor (FXR) to downregulate FXR signaling, as opposed to isoDCA, which is a potent FXR agonist to upregulate FXR signaling. In conclusion, we unveiled the opposing roles of 7-oxo-DCA and isoDCA to promote or inhibit intestinal tumorigenesis, respectively. Manipulating the BA-FXR axis during tumor initiation and progression holds great promise for developing innovative diagnostic and therapeutic approaches for the treatment of colorectal cancer.

Highland Barley Alleviates High-Fat Diet-Induced Obesity and Liver Injury Through the IRS2/PI3K/AKT Signaling Pathway in Rats

Objectives: Highland barley (HB) consumption offers numerous health benefits; however, its impact on glycolipid metabolism abnormalities induced by a high-fat diet remains unclear. Consequently, this study aimed to investigate the therapeutic effects and underlying molecular mechanisms of HB in the context of obesity; Methods: Rats were fed either a high-fat diet (HFD) to induce obesity or a standard diet (SD) for six weeks. The rats in the HFD group were randomly assigned into five groups: HFD+HFD, HFD+SD, and low (30%), medium (45%), and high (60%) doses of the HB diet for an additional ten weeks. Analyses of serum lipid profiles, liver histology, transcriptomes, and untargeted metabolomes were conducted; Results: HB intake resulted in decreased weight gain, reduced feed intake, lower serum triglyceride and cholesterol levels, and diminished hepatic lipid accumulation. It also improved insulin and fasting blood glucose levels, and antioxidant capacity in the HFD-fed rats. Transcriptome analysis revealed that HB supplementation significantly suppressed the HFD-induced increase in the expression of Angptl8, Apof, CYP7A1, GDF15, Marveld1, and Nr0b2. Furthermore, HB supplementation reversed the HFD-induced decrease in Pex11a expression. Untargeted metabolome analysis indicated that HB primarily influenced the pentose phosphate pathway, the Warburg effect, and tryptophan metabolism. Additionally, integrated transcriptome and metabolome analyses demonstrated that the treatments affected the expression of genes associated with glycolipid metabolism, specifically ABCG8, CYP2C12, CYP2C24, CYP7A1, and IRS2. Western blotting confirmed that HB supplementation impacted the IRS2/PI3K/AKT signaling pathway; Conclusions: HB alleviates HFD-induced obesity and liver injury in an obese rat model possibly through the IRS2/PI3K/Akt signaling pathway.

Targeting nuclear receptors for NASH/MASH: From bench to bedside

The onset of metabolic dysfunction-associated steatohepatitis (MASH) or non-alcoholic steatohepatitis (NASH) represents a tipping point leading to liver injury and subsequent hepatic complications in the natural progression of what is now termed metabolic dysfunction-associated steatotic liver diseases (MASLD), formerly known as non-alcoholic fatty liver disease (NAFLD). With no pharmacological treatment currently available for MASH/NASH, the race is on to develop drugs targeting multiple facets of hepatic metabolism, inflammation, and pro-fibrotic events, which are major drivers of MASH. Nuclear receptors (NRs) regulate genomic transcription upon binding to lipophilic ligands and govern multiple aspects of liver metabolism and inflammation. Ligands of NRs may include hormones, lipids, bile acids, and synthetic ligands, which upon binding to NRs regulate the transcriptional activities of target genes. NR ligands are presently the most promising drug candidates expected to receive approval from the United States Food and Drug Administration as a pharmacological treatment for MASH. This review aims to cover the current understanding of NRs, including nuclear hormone receptors, non-steroid hormone receptors, circadian NRs, and orphan NRs, which are currently undergoing clinical trials for MASH treatment, along with NRs that have shown promising results in preclinical studies.