Rescue of Mitochondrial SIRT3 Ameliorates Ischemia-like Injury in Human Endothelial Cells

Structural and functional alterations of vasculature caused by age-related factors is critically involved in the pathogenesis of ischemic stroke. The longevity genes sirtuins (SIRTs) are extensively investigated in aging-associated pathologies, but their distinct roles in ischemic stroke still remain to be clarified. To address this question, we applied oxygen and glucose deprived/reperfusion (OGD/R) to induce ischemic injury in human endothelial cells (ECs), which are the main component of vasculature in the brain. The results showed that OGD/R led to various damages to ECs, including compromised cell viability, increased LDH release, overproduced ROS, enhanced apoptosis and caspase activity. Meanwhile, the expression of mitochondrial SIRT3 was robustly decreased in ECs after OGD/R treatment. Consistently, rescue of SIRT3 by ectopic expression, but not nuclear SIRT1, in ECs reversed the OGD/R-induced cell damage. Interestingly, some front-line drugs for ischemic stroke, including clopidogrel, aspirin and dl-3-n-butylphthalide (NBP), also rescued SIRT3 and reduced OGD/R-induced endothelial injury, suggesting that the recovery of SIRT3 expression was critical for the protection of these drugs. Moreover, our results demonstrated that 10-hydroxy-NBP (OHNBP), a major metabolite of NBP, showed better blood-brain barrier crossing capability than NBP, but still retained the effects on SIRT3 by NBP. Together, our results suggested that SIRT3 may serve as a potential novel target for treatment of ischemic stroke.

Automated summary

The structural and functional changes in blood vessels play a critical role in the development of ischemic stroke caused by aging-related factors. The longevity genes sirtuins (SIRTs) have been extensively studied in age-related pathologies, but their specific roles in ischemic stroke are still unclear. In this study, human endothelial cells (ECs) were exposed to oxygen and glucose deprivation/reperfusion (OGD/R) to induce ischemic injury. The results showed that OGD/R caused various damages to ECs and led to a decrease in the expression of mitochondrial SIRT3. Interestingly, several frontline drugs for ischemic stroke were found to rescue SIRT3 expression and reduce endothelial injury caused by OGD/R. Additionally, a major metabolite of one of these drugs showed better blood-brain barrier crossing capability while still maintaining the effects on SIRT3 expression. These findings suggest that SIRT3 may serve as a potential therapeutic target for ischemic stroke.