Vildagliptin attenuates the development of CCl₄-induced liver fibrosis: associations with gut-liver axis modulation and LPS/notch-related signaling.

Liver fibrosis is a progressive pathological condition closely linked to gut microbiota dysbiosis and impaired intestinal barrier integrity. Vildagliptin, a dipeptidyl peptidase-4 inhibitor used in type 2 diabetes, exhibits pleiotropic anti-inflammatory and antioxidant properties; however, its impact on the gut-liver axis during hepatic fibrogenesis remains insufficiently defined. This experimental study investigated whether concomitant vildagliptin administration attenuates the development of CCl₄-induced liver fibrosis and whether this effect is associated with alteration in gut microbial composition, intestinal barrier-related markers, and circulating lipopolysaccharide (LPS), and hepatic fibrosis-associated molecular changes. Male rats were allocated to five groups: normal control, Vildagliptin alone (20 mg/kg/day), CCl₄-fibrosis, and CCl₄ + Vildagliptin (10 or 20 mg/kg/day). Liver fibrosis was induced by CCl₄ administration for six weeks, with concomitant daily oral Vildagliptin in the treatment groups. Liver function indices, fibrotic markers, oxidative stress parameters, and serum LPS were assessed. Intestinal barrier-related changes were assessed by measuring colonic ZO-1 and occludin levels, while circulating LPS was quantified as a marker of systemic endotoxemia. Hepatic ADAM17, Notch-1, DNMT3A, and Smad7 protein levels and β-Klotho mRNA expression were assessed. Liver and colon histopathology was examined, and gut microbiota composition was profiled using 16S rRNA gene amplicon sequencing. Vildagliptin significantly ameliorated CCl₄-induced liver injury and fibrosis, evidenced by improved biochemical parameters, reduced collagen deposition and hydroxyproline, and attenuation of hepatic stellate cell activation. These effects were accompanied by increased colonic ZO-1 and occludin levels, reduced circulating LPS, decreased hepatic ADAM17, Notch-1, and DNMT3A protein levels, increased β-Klotho mRNA expression and Smad7 protein levels, and alterations in gut microbiota composition. Collectively, concomitant vildagliptin administration attenuated the development of CCl₄-induced liver fibrosis and was associated with modulation of gut-liver axis -related changes and alterations in LPS- and Notch-related molecular markers.