BackgroundThe 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 resultsSingle-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. ConclusionsThese 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.
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