Protection of hepatocyte mitochondrial function by blueberry juice and probiotics via SIRT1 regulation in non-alcoholic fatty liver disease

Mitochondrial dysfunction has been implicated in the pathogenesis of nonalcoholic fatty liver disease (NAFLD). Our previous study has firstly reported that blueberry juice and probiotics (BP) effectively protect liver function in NAFLD. However, the role of BP in hepatic mitochondria is unknown. Here, we aimed to investigate the effects and mechanisms of BP on the mitochondrial function and oxidative stress of rats with NAFLD. The NAFLD rat models were established and treated with BP and SIRT1 siRNA. The mitochondrial ultrastructure was analyzed by electron microscopy, reactive oxygen species (ROS) was detected by immunofluorescence, and biomarkers of mitochondrial function and oxidative stress were examined via quantitative reverse transcription-PCR, western blot, and immunohistochemistry. Results revealed that BP significantly reversed the NAFLD-induced hepatic mitochondrial damage, mitochondrial swelling, and hepatic necrosis. In particular, BP significantly restored the mitochondrial respiratory function of NAFLD rats by decreasing state 4 and 3 respiration rates, by increasing the respiration control ratio (RCR) and the ADP/O ratio, and by enhancing ATP, ADP, AMP, and EC syntheses. Moreover, BP reduced mitochondrial oxidative stress in NAFLD by decreasing the MDA level, elevating the GSH and SOD levels, and suppressing the ROS activity. Importantly, SIRT1 deficiency significantly abolished the effects of BP on the mitochondria and oxidative stress. Furthermore, BP reversed the decline of PGC-1 expression induced by NAFLD, while SIRT1 silencing significantly suppressed the effects of BP on PGC-1. In conclusion, BP might effectively protect rats against mitochondrial dysfunction during NAFLD as potential ingredients of functional food, by modulating the SIRT1 expression. Potential endogenous modulators of NAFLD pathogenesis may ultimately provide novel tools for therapeutic intervention.