Hammerhead-type FXR agonists induce an enhancer RNA Fincor that ameliorates nonalcoholic steatohepatitis in mice

FXR protects against neonatal sepsis by enhancing the immunosuppressive function of MDSCs

Myeloid-derived suppressor cells (MDSCs) play a protective role against neonatal inflammation during the early postnatal period. However, the mechanisms regulating neonatal MDSC function remain to be fully elucidated. In this study, we report that the bile acid receptor farnesoid X receptor (FXR) acts as a positive regulator of neonatal MDSC function. The FDA-approved FXR agonist obeticholic acid (OCA) protects against neonatal sepsis in an FXR-dependent manner. Genetic deficiency of FXR impairs the immunosuppressive and antibacterial functions of MDSCs, thereby exacerbating the severity of neonatal sepsis. Adoptive transfer of MDSCs alleviates sepsis in both Fxr-/- and Fxrfl/flMrp8-Cre+ pups. Mechanistic studies revealed that Hif1α, a well-established regulator of MDSCs, is a direct transcriptional target of FXR. In patients with neonatal sepsis, downregulation of FXR and HIF-1α in MDSCs was observed, which was inversely correlated with clinical parameters. These observations demonstrate the importance of FXR in neonatal MDSC function and its therapeutic potential in neonatal sepsis.

Changes in the FXR-cistrome and alterations in bile acid physiology in Wilson disease

BACKGROUND

Wilson disease (WD) is an autosomal recessive disorder that results in excessive hepatic copper, causing hepatic steatosis, inflammation, fibrosis, cirrhosis, and liver failure. Previous studies have revealed dysregulation of many farnesoid X receptor (FXR) metabolic target genes in WD, including the bile salt exporter pump, the major determinant of bile flow.

METHODS

We tested the hypothesis that the FXR-cistrome is decreased in Atp7b-/- mice in accord with dysregulated bile acid homeostasis.

RESULTS

FXR binding within Atp7b-/- mouse livers displayed surprising complexity: FXR binding was increased in distal intergenic regions but decreased in promoter regions in Atp7b-/- versus wild-type mice. Decreased FXR occupancy in Atp7b-/- versus wild-type mice was observed in hepatocyte metabolic and bile acid homeostasis pathways, while enrichment of FXR binding was observed in pathways associated with cellular damage outside of hepatocytes. Indeed, disparate FXR occupancy was identified in parenchymal and non-parenchymal marker genes in a manner that suggests decreased FXR activity in parenchymal cells, as expected, and increased FXR activity in non-parenchymal cells. Consistent with altered FXR function, serum and liver bile acid concentrations were higher in Atp7b-/- mice than in wild-type mice. Comparison of bile acid profiles in the serum of WD patients with "liver," "neurological," or "mixed" disease versus healthy controls also revealed increases in specific bile acids in WD-liver versus healthy controls.

CONCLUSIONS

We identified novel FXR-occupancy across the genome that varied in parenchymal and non-parenchymal cells, demonstrating complex FXR regulation of metabolic and hepatocellular stress pathways in Atp7b-/- mice. Dynamic changes in FXR activity support our novel finding of altered bile acid metabolism in Atp7b-/- mice and WD patients.

LncRNAs, RNA Therapeutics, and Emerging Technologies in Liver Pathobiology

The field of ribonucleic acid (RNA) biology has revealed an array of noncoding RNA species, particularly long noncoding RNAs (lncRNAs), which play crucial roles in liver disease pathogenesis. This review explores the diverse functions of lncRNAs in liver pathology, including metabolic-associated steatotic liver disease, hepatocellular carcinoma, alcohol-related liver disease, and cholangiopathies such as primary sclerosing cholangitis and cholangiocarcinoma. We highlight key lncRNAs that regulate lipid metabolism, inflammation, fibrosis, and oncogenesis in the liver, demonstrating their diagnostic and therapeutic potential. Emerging RNA-based therapies, such as mRNA therapy, RNA interference, and antisense oligonucleotides, offer approaches to modulate lncRNA activity and address liver disease at a molecular level. Advances in sequencing technologies and bioinformatics pipelines are simultaneously enabling the identification and functional characterization of novel lncRNAs, driving innovation in personalized medicine. In conclusion, this review highlights the potential of lncRNAs as biomarkers and therapeutic targets in liver disease and emphasizes the need for further research into their regulatory mechanisms and clinical applications.