Decreased MFN2 activates the cGAS-STING pathway in diabetic myocardial ischaemia-reperfusion by triggering the release of mitochondrial DNA

BACKGROUND

The cause of aggravation of diabetic myocardial damage is yet to be elucidated; damage to mitochondrial function has been a longstanding focus of research. During diabetic myocardial ischaemia-reperfusion (MI/R), it remains unclear whether reduced mitochondrial fusion exacerbates myocardial injury by generating free damaged mitochondrial DNA (mitoDNA) and activating the cGAS-STING pathway.

METHODS

In this study, a mouse model of diabetes was established (by feeding mice a high-fat diet (HFD) plus a low dose of streptozotocin (STZ)), a MI/R model was established by cardiac ischaemia for 2 h and reperfusion for 30 min, and a cellular model of glycolipid toxicity induced by high glucose (HG) and palmitic acid (PA) was established in H9C2 cells.

RESULTS

We observed that altered mitochondrial dynamics during diabetic MI/R led to increased mitoDNA in the cytosol, activation of the cGAS-STING pathway, and phosphorylation of the downstream targets TBK1 and IRF3. In the cellular model we found that cytosolic mitoDNA was the result of reduced mitochondrial fusion induced by HG and PA, which also resulted in cGAS-STING signalling and activation of downstream targets. Moreover, inhibition of STING by H-151 significantly ameliorated myocardial injury induced by MFN2 knockdown in both the cell and mouse models. The use of a fat-soluble antioxidant CoQ10 improved cardiac function in the mouse models.

CONCLUSIONS

Our study elucidated the critical role of cGAS-STING activation, triggered by increased cytosolic mitoDNA due to decreased mitochondrial fusion, in the pathogenesis of diabetic MI/R injury. This provides preclinical insights for the treatment of diabetic MI/R injury. Video Abstract.

Long-term outcomes of percutaneous coronary intervention in grafts and native vessels in coronary artery bypass grafting patients with diabetes mellitus

Background

Atherosclerosis in diabetic patients progresses fast. Evidence on how to choose target vessels of percutaneous coronary interventions (PCIs) in diabetic patients post-coronary artery bypass graft (post-CABG) is insufficient.

Methods

One hundred and fifty-seven patients with diabetes and previous CABG, who underwent PCI of either a graft vessel (GV) (n=44) or a native vessel (NV) (n=113) in the National Center for Cardiovascular Disease, China, were studied. In-hospital and long-term clinical outcomes were compared between the groups.

Results

Diabetic patients with prior CABG had more PCI to native arteries, but the proportion of grafts PCI increased as time went on. Both groups had similar baseline characteristics. Group GV patients compared with group NV had more totally occluded NVs, less totally occluded grafts and more in-stent restenosis. However, there was no difference in in-hospital mortality and long-term incidence of major adverse cardiac event (MACE), cardiac death, nonfatal myocardial infarction (MI), or revascularization. Multivariate logistic regression analysis showed that PCI success [hazard ratio (HR), 11.488; 95% confidence interval (CI), 1.135-116.303; P<0.05] was independent predictor of MACE.

Conclusions

It suggested similar long-term clinical outcomes after PCI in GV or NV in prior CABG patients with diabetes. Thus, the vessel with higher estimated PCI success rate should be prioritized by operators.