Cold aerobic exercise mitigates NAFLD fibrosis through UBAP2L-regulated TGFβ/Smad2 signaling.

Non-alcoholic fatty liver disease (NAFLD) can progress to fibrosis and hepatocellular carcinoma, with TGFβ playing a key role. UBAP2L regulates TGFβ expression, but its role in NAFLD remains unclear. While exercise improves NAFLD and cold exposure enhances lipid metabolism, their combined effects on NAFLD-induced fibrosis are unknown. This study examines whether exercise with cold exposure (ECE) attenuates NAFLD-induced fibrosis via UBAP2L-mediated TGFβ/Smad2/3 pathway. Fifty 5-week-old male C57BL/6N mice were assigned to five groups: normal control (C), high-fat diet (H), high-fat diet with cold exposure (HC), high-fat diet with exercise (HE), and high-fat diet with ECE (HCE). After 8 weeks of high-fat diet feeding, the HE and HCE groups underwent treadmill exercise (50 minutes/session, 5 days/week for 8 weeks). HE, Oil Red O, Masson staining, biochemical analyses, proteomics, WB, and RT-qPCR were used to assess fibrosis-related markers. We found that body weight, liver weight, hepatic TG, TC, LDL, Glu, CHO, and AST, ALT were significantly elevated in H group. In HCE group, hepatic TG and BUN decreased, while HDL increased. Proteomics identified UBAP2L as the most upregulated protein in H group, but it was downregulated in HCE group. WB confirmed UBAP2L overexpression in H group and its reduction in HCE group, with decreased α-SMA. RT-qPCR showed elevated TGFβ, α-SMA, Smad2, Smad3, Col1a2 and UBAP2L in H group, which were downregulated by ECE. ECE reduces NAFLD-induced hepatic fibrosis, probably by downregulating UBAP2L and suppressing TGFβ/Smad2 pathway. These suggest ECE may be more effective than exercise at normal temperatures in Mitigating NAFLD-related fibrosis.