Circulating interleukins in relation to coronary artery disease, atrial fibrillation and ischemic stroke and its subtypes: A two-sample Mendelian randomization study.

BACKGROUND: The causal role of interleukins (ILs) for cardiovascular disease has not been fully elucidated. We conducted a Mendelian randomization study to investigate the associations of circulating ILs with coronary artery disease (CAD), atrial fibrillation (AF), and ischemic stroke.

METHODS AND RESULTS: Single-nucleotide polymorphisms associated with IL-1β, IL-1 receptor antagonist (IL-1ra), IL-2 receptor subunit alpha, IL-6, IL-16, IL-17 and IL-18 were identified from genome-wide association studies. Summary-level data of the outcomes were obtained from three large consortia. Genetic predisposition to higher IL-1ra levels were significantly associated with CAD. The odds ratio was 1.36 (95% confidence interval (CI), 1.14-1.63; P = 5.37 × 10-4 ) per one standard deviation increase in IL-1ra levels. Genetically higher IL-6 levels, predicted by a variant in the IL6R gene and corresponding to reduced IL-6 bio-function, were significantly inversely associated with CAD and AF. The odds ratios per one standard deviation increase in IL-6 levels were 0.64 (95%CI, 0.54-0.76; P = 2.22 × 10-7 ) for CAD and 0.70 (95%CI, 0.62-0.80; P = 1.34 × 10-7 ) for AF. There was a suggestive positive association of IL-1ra with cardioembolic stroke and suggestive inverse associations of IL-6 with any ischemic stroke, cardioembolic stroke, and small vessel stroke, and of IL-16 with CAD. The other ILs were not associated with any outcome.

CONCLUSIONS: These results strengthen the evidence that IL-6 inhibition may offer a therapeutic approach for prevention of CAD, AF, and ischemic stroke. In contrast, IL-1 inhibition through raised IL-1ra levels may confer increased risk of CAD and cardioembolic stroke. The role of IL-16 for CAD warrants further investigation.