High-fat diet-derived metabolite uridine diphosphate (UDP) impairs epithelial regeneration by P2Y 6 -receptor signaling.

Obesity is associated with a chronic low-grade inflammation affecting metabolic changes and organ dysfunction. Impairment of the intestinal epithelial barrier (IEB) and alterations in gut microbiota are considered to contribute to this phenotype by largely undefined mechanisms. Here, we used a diet-induced obesity model in rats to investigate the early interplay between a high-fat diet (HFD), gut microbiota composition, metabolic stool contents and IEB regeneration. Male Wistar rats received either a high-fat diet or a low-fat diet (LFD) ad libitum. HFD feeding resulted in weight gain and impaired oral glucose tolerance. Impairment of IEB function was evident by augmented lipopolysaccharide levels in the blood and reduced expression of junctional proteins Claudin-3, 4, and Desmoglein-2 in colonic samples of HFD rats. 16S-rRNA marker-gene sequencing of colonic microbiota revealed decreased phylogenetic diversity in HFD rats and significant alterations in microbial community composition. Detailed analysis revealed that content from HFD rats impaired intestinal epithelial regeneration in organoid assays. Metabolomic profiling identified uridine monophosphate/uridine diphosphate (UMP/UDP) metabolites as strongly enriched in HFD samples. UDP emerged as a key metabolite mediating impaired epithelial regeneration through P2Y6 receptor signaling, as pharmacological inhibition of P2Y6 with antagonist MRS2578 attenuated both UDP- and HFD-induced loss of epithelial regeneration. In summary, these data demonstrate that the diet-dependent stool metabolite UDP compromises intestinal epithelial repair via P2Y6 receptor signaling in early obesity. These findings link impaired epithelial regeneration to the onset of obesity-associated low-grade inflammation.