Abstract
BACKGROUND: Observational studies have suggested the potential role of inflammatory factors in the risk of coronary artery disease (CAD). We aimed to perform 2-sample Mendelian randomization (MR) analyses to assess the causal association between circulating cytokines/growth factors and CAD. METHODS AND RESULTS: The instrumental variables for 28 circulating cytokines and growth factors were identified from a genome-wide association study of 8293 European participants. Summary-level data on CAD were derived from a large genome-wide association study (71 602 cases and 260 875 controls). We used the inverse-variance-weighted and Wald ratio methods as our main MR methods. The weighted median, simple median, maximum likelihood, MR pleiotropy residual sum and outlier, and MR-Egger methods were performed as sensitivity analyses. Genetic colocalization analyses were conducted to validate the robustness of our MR findings. We found that genetically predicted circulating levels of macrophage migration inhibitory factor were associated with an increased risk of CAD at the Bonferroni-adjusted level of significance (P<1.79×10(-3)). The odds ratio was 1.20 (95% CI, 1.08-1.33; P=6.83×10(-4)) per 1-SD increase in macrophage migration inhibitory factor. Colocalization analyses supported our MR findings. Additionally, we found suggestive evidence between the genetic effects of stem cell growth factor-β and the risk of CAD (odds ratio, 0.95 [95% CI, 0.91-0.98]; P=0.007). CONCLUSIONS: Our findings suggested a risk-increasing effect of macrophage migration inhibitory factor level on the development of CAD. The roles of these inflammatory factors for CAD warrant further investigation.