Inflammation and heart failure: a two-sample Mendelian randomization study

Background It is hypothesized that inflammation leads to heart failure. Results from observational studies thus far have been inconsistent and it is unclear whether inflammation is causally associated with new-onset heart failure. Mendelian randomization analyses are less prone to biases common in observational studies such as reverse causation and unmeasured confounding. The aim of this study was to investigate the causal relation between various inflammatory biomarkers with risk of new-onset heart failure by using a two-sample Mendelian randomization approach. Methods Ten inflammatory biomarkers with available genome-wide association studies (GWAS) among individuals of European ancestry were identified and included C-reactive protein (CRP), immunoglobulin E, tumour necrosis factor (TNF), toll-like receptor 4, interleukin 1 receptor antagonist, interleukin 2 receptor subunit alpha, interleukin 6 receptor subunit alpha, interleukin 16, 17 and 18. For the associations between the identified SNPs and heart failure, we used the largest GWAS meta-analysis performed by the Heart Failure Molecular Epidemiology for Therapeutic Targets Consortium with 47 309 participants with heart failure and 930 014 controls. For our main analyses, we used the inverse-variance weighted method. Results We included 63 SNPs. CRP, TNF, interleukin 2, 16 and 18 were not associated with heart failure with odds ratios (ORs) of 1.01 [95% confidence interval (95% CI: 0.94-1.09), 1.11 (95% CI: 0.80-1.48), 0.97 (95% CI: 0.93-1.02), 0.99 (95% CI: 0.96-1.03) and 1.01 (95% CI: 0.97-1.06), respectively. The other biomarkers were also not associated with the risk of heart failure and suffered from weak instrument bias. Conclusion This Mendelian randomization study could not determine a causal relationship between inflammation and risk of heart failure. However, some biomarkers suffered from weak instrument bias.