FXR Stimulation by Obeticholic Acid Treatment Restores Gut Mucosa Functional and Structural Integrity in Individuals With Altered Glucose Tolerance

The farnesoid X receptor (FXR)–fibroblast growth factor 19 (FGF19) axis is involved in maintaining glucose homeostasis and gut tight-junction (TJ) integrity. We evaluated whether individuals with prediabetes or type 2 diabetes (T2D) have altered intestinal FXR-FGF19 signaling and barrier function and whether high-glucose (HG) exposure may cause these aberrations. Moreover, we tested beneficial effects of the FXR agonist obeticholic acid (OCA) on intestinal FXR signaling in individuals with prediabetes or T2D. Included were 60 individuals with different glucose tolerance (normal glucose tolerance [NGT; n = 25], prediabetes [n = 19], or T2D [n = 16])who underwent ileocolonoscopy with collection of ileal mucosa biopsy specimens, which were used for expression profiling analysis of the FXR/FGF19/TJ axis and tissue culture experiments. Individuals with prediabetes or T2D displayed lower ileal levels of FXR and its target genes FGF19 and TJ proteins zonula, occludens-1, occludin, and claudin-1, along with increased proinflammatory nuclear factor-kB (NF-kB) activity and cytokines expression compared with those with NGT. HG exposure on ileal explants collected from NGT individuals hampered the FXR/FGF19/TJ axis. OCA treatment on ileal fragments of individuals with prediabetes/T2D was able to restore FGF19 synthesis and secretion, TJ expression, and counteract NF-kB activity and cytokines expression. In conclusion, OCA treatment counteracts T2D-related intestinal abnormalities in the FXR/FGF19/TJ axis.