Background and aims

Age is a dominant and independent risk factor for the development of atherosclerosis, a major cardiovascular disease, and if left untreated leads to myocardial infarction and death. Mitochondria-targeted anti-oxidants are evolving as a new class of compounds that can alter the pathophysiology of age-related diseases, including atherosclerosis, where mitochondrial dysfunction plays a critical role in disease progression.

Methods

We recently synthesized an alkyl TPP + -tagged esculetin (mitochondria-targeted esculetin or Mito-Esc). Apoe^−/− mice were chronically (14 months) administered with Mito-Esc to investigate its efficacy in the mitigation of atherosclerosis in the setting of aging. We monitored BP, and performed various biochemical assays, histopathology, immunohistochemistry, inflammatory factors, qPCR, and Western blotting. Simultaneously, human aortic endothelial cells (HAECs) were used as a model system to study the mechanistic aspects.

Results

A chronic low-dose administration of Mito-Esc to Apoe^−/− mice greatly prevented alterations in lipid profile, blood pressure, and atherosclerotic plaque formation in the setting of aging. Mito-Esc administration significantly reduced vascular senescence and pro-inflammatory cytokines levels and prevented dysregulation of mitochondrial biogenesis markers in aortic tissue. Further, Mito-Esc treatment prevented replicative and stress-induced premature senescence (SIPS) in HAEC. Importantly, Mito-Esc treatment delayed endothelial cell senescence by increasing human telomerase reverse transcriptase (hTERT) levels via SIRT1 activation. Moreover, Mito-Esc treatment by altering miR-19b and miR-30c via a SIRT1 activation significantly inhibited the increase in PAI-1 levels in HAEC as well as in the serum of Apoe^−/− mice. In addition, Mito-Esc treatment improved mitochondrial function in late passage (aged) HAECs by enhancing the oxygen consumption rate (OCR). Furthermore, Mito-Esc administration counteracted the decline in GSH and nitrite levels in Apoe^−/− mice and in HAECs.

Conclusions

Overall, Mito-Esc alleviates atherosclerosis in the setting of aging by delaying vascular senescence and pro-inflammatory processes, and by improving mitochondrial biogenesis and function.