Genetic Downregulation of Interleukin-6 Signaling, Coagulation Function, and Risk of Thromboembolic Disease

Although genetic evidence supports IL-6 (interleukin-6) signaling inhibition as protective against atherosclerotic disease, its potential effects on thromboembolic outcomes are not well established. We conducted a Mendelian randomization analysis to investigate the association of genetically proxied IL-6 signaling inhibition with venous thromboembolism, cardioembolic stroke, and coagulation cascade protein levels.

IL-6 signaling inhibition was proxied using the rs2228145 IL6R missense variant, which impairs classical IL-6 signaling and lowers CRP (C-reactive protein) levels. Genetic associations with thromboembolic disease outcomes were obtained from genome-wide association studies of venous thromboembolism (81 190 cases) and cardioembolic stroke (10 804 cases). As atherosclerotic comparator traits, we included coronary artery disease (181 522 cases) and large-artery atherosclerotic stroke (6399 cases). Genetic associations with 35 coagulation cascade protein levels were obtained from the UK Biobank (n=6218) and deCODE cohorts (n=35 559). Mendelian randomization estimates were derived using the Wald ratio method, scaled per 1-unit decrease in natural log-transformed CRP levels.

Genetically proxied IL-6 signaling inhibition was associated with increased risk of venous thromboembolism (odds ratio [OR], 1.31 [95% CI, 1.16-1.47], P=6.5×10^-6) but not with cardioembolic stroke (OR, 1.25 [95% CI, 0.73-2.14], P=0.42). Conversely, protective associations were observed for both coronary artery disease and large-artery atherosclerotic stroke. Proteomic analyses demonstrated significant reductions in levels of 5 procoagulant and 7 anticoagulant or antifibrinolytic proteins.

These findings suggest that IL-6 signaling inhibition dysregulates coagulation homeostasis and increases venous thromboembolism risk. Further experimental, translational, and epidemiologic studies are warranted to delineate underlying mechanisms and to evaluate thromboembolic safety in pharmacologic IL-6 signaling inhibition.