Joint effects of mitochondrial DNA4977 deletion and serum folate deficiency on coronary artery disease in type 2 diabetes mellitus.

BACKGROUND & AIMS: The 4977-bp mitochondrial deletion (mtDNA4977 deletion), as a hallmark of mitochondrial oxidative damage, may play an important role in coronary artery disease (CAD), but its interaction with folate deficiency among diabetic patients is largely unknown. We aimed to explore the joint association of leukocyte mtDNA4977 deletion and serum folate status with obstructive CAD in Chinese adults with type 2 diabetes. METHODS: We cross-sectionally analyzed the angiographic data of 2017 diabetic patients without B-vitamin supplementation. Of the 2017 participants, 756 who received percutaneous coronary intervention (PCI) completed prospective follow-up of one year. In vitro, we explored the mediation effects of mitochondrial reactive oxygen species (mtROS) in folic acid (FA)-deficient human aortic smooth muscle cells (HASMCs) under hyperglycemic conditions. RESULTS: Cross-sectionally, the multivariate odds ratios (ORs) for obstructive CAD were 1.41 (95% CI: 1.29-1.55) for greater mtDNA4977 deletion, and 1.15 (95% CI: 1.05-1.25) for lower folate levels. Particularly, the combination of high mtDNA4977 deletion (top tertile) and folate deficiency (serum folate < 6 ng/mL) was associated with more than 2-fold increased odds of having obstructive CAD and higher degrees of coronary stenosis. Prospectively, the hazard ratio for all-cause death at 1-year after PCI was up to 2.37 (95% CI: 1.21-4.63) for folate-deficient participants in the top tertile of mtDNA4977 deletion. In HASMCs, the adverse effects of FA deficiency were aggravated by induction of mtROS, and attenuated by scavenging of mtROS. CONCLUSIONS: The risk of obstructive CAD may be greatly increased by the interaction between greater mtDNA4977 deletion and folate deficiency among diabetic patients.