Abstract 10714: The Role of Interleukin-6 in Heart Failure and Its Subtypes: Results from Mendelian Randomization and Mediation Analysis

Abstract

Introduction: Heart failure (HF) increases morbidity, mortality, and costs, with complex pathogenic mechanisms. Interleukin-6 (IL-6) is a key cytokine and immune regulator with broad impact on inflammation – a critical component of HF pathophysiology. Circulating levels of IL-6 receptor (IL-6R) determines the activity of the IL-6 signaling pathway. We aim to estimate the causal effect of the IL-6R on HF and two clinical subtypes: HF with reduced (HFrEF) and preserved ejection fraction (HFpEF) in a Mendelian Randomization (MR) framework including mediators. Hypothesis: Plausible causal associations between IL-6R and HF, HFrEF and HFpEF are mediated by body mass index (BMI) or coronary artery disease (CAD). Methods: Two-sample MR analyses were conducted using genetic association results for composite HF, HFrEF and HFpEF among >300,000 MVP participants of European ancestry. Thirty-four independent genetic variants within 250 kb from the IL6R gene associated with plasma IL-6R levels were used as genetic instrumental variables. We estimated the direct effect of IL-6R levels on HF and subtypes, and the indirect effect mediated through BMI and CAD. Results: Causal effects of IL-6R on composite HF, HFrEF and HFpEF were estimated as odds ratios (OR): 0.97 (CI 0.96-0.99, p=0.02), 0.96 (CI 0.93-0.98, p=0.003) and 1.00 (CI 0.97-1.03, p=0.89), respectively. Mediation analyses for composite HF and HFrEF showed significant mediation effects by CAD, with ORs 0.98 (CI 0.97-0.99) and 0.98 (CI 0.96-1.00), respectively. No mediation effect of BMI was identified. Conclusions: These findings support a causal role of IL-6 signaling in composite HF and HFrEF, but not HFpEF. Although the IL-6 signaling pathway plays a role in both BMI and CAD, the effect of IL-6 signaling on composite HF and HFrEF may be mediated through by CAD. Our findings demonstrate the role of IL-6 signaling in HF and its difference between HF subtypes, which may lead to more specific therapeutic targets for HF.