Telomere length mediates the causal effects of excess adiposity on cardiovascular risk: A two-step Mendelian randomization study.

Background and aims: Excess adiposity correlate to cardiovascular diseases, inflammation, and telomere shortening, while the latter two are associated with cardiovascular risks. Whether inflammation and telomere length mediate the excess adiposity-cardiovascular relationship is unclear.

Methods and results: We performed a two-step Mendelian randomization analysis utilizing data from the latest genome-wide association studies: body mass index (BMI, n = 681,275), waist-to-hip ratio (WHR, n = 697,734) and BMI adjusted WHR (WHR_adjBMI, n = 694,649), telomere length (n = 472,174), C-reactive protein (n = 204,402), interleukin-6 and interleukin-1 receptor antagonist (n = 21,758), tumor necrosis factor-α (n = 3454), hypertension (n = 463,010), coronary artery disease (n = 547,261), heart failure (n = 977,323), stroke (n = 446,696), ischemic stroke (n = 440,328), intracerebral hemorrhage (n = 343,663), aortic aneurysm (n = 356,934), transient ischemic attack (n = 360,692), peripheral vascular disease (n = 463,010), systolic and diastolic blood pressure changes (n = 757,601). We observed casual effects of excess adiposity on eight cardiovascular diseases, hypertension and blood pressure changes. Telomere length is causally associated with hypertension, blood pressure, coronary artery disease, aortic aneurysm, and intracerebral hemorrhage, mediates BMI's effect on coronary artery disease (2.41 %) and aortic aneurysm (4.97 %), and plays a suppressive role between WHR and systolic blood pressure changes (2.39 %).

Conclusion: Telomere length mediates the causal effects of excess adiposity on the risks of coronary artery disease, aortic aneurysm, and systolic blood pressure changes.