Active vitamin D supplementation alleviates initiation and progression of nonalcoholic fatty liver disease by repressing the p53 pathway

Background/aims: Recent studies have found vitamin D deficiency promotes fat deposition into the hepatocytes, thus contributing to the development of nonalcoholic fatty liver disease (NAFLD), which is a hepatic manifestation of metabolic syndrome. This study aimed to investigate the potential effects of vitamin D on NAFLD with the involvement of the p53 pathway. Methods: Initially, an in vivo high-fat diet (HFD)-induced NAFLD mouse model was established. Then the HFD-induced NAFLD mice were treated with vitamin D. Next, the serum levels of TNF-alpha, GSH-px and malondialdehyde (MDA) were assessed using ELISA and ROS content was evaluated by flow cytometry, followed by the measurement of expression of Duox1, Duox2, SOD1, SOD2, PRDX1 I, ACC, SREBP1c, MTTP, PPAR alpha, p53, p21 and p16 using RT-qPCR and Western blot analysis. Positive expression of FAS and FASL proteins was measured using immunohistochemistry. TUNEL and Senescence-associated beta-galactosidase (SA-beta-Gal) staining were subsequently conducted to assess the senescence and apoptosis of hepatocytes. Results: HFD-induced mice treated with vitamin D presented with significantly increased GSH-px levels, as well as protein expression of SOD1, SOD2, PRDX1, MTTP and PPARa, but decreased MDA and ROS levels, expression of Duox1, Duox2, ACC, SREBP1c, p53, p21 and p16, positive expression of FAS and FASL proteins as well as impaired senescence and apoptosis of hepatocytes. Conclusion: Active vitamin D supplementation could potentially impede hepatocyte senescence and apoptosis via suppression of the p53 pathway, thus preventing the progression of NAFLD. Our study provides available evidence on the potential clinical utility of vitamin D supplementation in NAFLD.