Interleukin-1 and Eosinophils in Heart Failure

Background. Anakinra, an IL-1 inhibitor, temporarily increases eosinophil blood levels in patients with acute myocardial infarction and reduces heart failure (HF) events. Anakinra is also frequently associated with injection site reactions (ISR), and eosinophils have been shown to play a role. Whether anakinra is associated with changes in eosinophils in patients with HF and whether these changes are linked to a different response in terms of cardiorespiratory fitness (CRF) is unknown. Moreover, whether ISR represents an eosinophilic response to anakinra and is associated with a different response to treatment in patients with HF also remains unclear. Aim. This study aims to explore the effect of anakinra on changes in eosinophils in patients with HF, and their correlation with CRF. Methods. We measured eosinophils in 64 patients with HF (50% females), 55 [51–63] years of age, before and after treatment, and, in a subset of 41 patients, also after treatment cessation. We also evaluated CRF by measuring peak oxygen consumption (peak VO2) with a treadmill test. Results. Treatment with anakinra led to a significant and transient increase in eosinophils, from 0.2 [0.1–0.3] to 0.3 [0.1–0.4] x103 cells/µL (p<0.001), and from 0.3 [0.2–0.5] to 0.2 [0.1–0.3] x103 cells/µL, with suspension (p<0.001). Changes in eosinophils correlated with the changes in peak VO2 (Spearman's Rho= +0.228, p=0.020) and predicted peak VO2 (Rho= +0.265, p=0.014). Patients experiencing ISR (n=8, 13%) had higher levels of eosinophils (0.5 [0.4–0.6] vs. 0.2 [0.1–0.4] x103 cells/µL, p=0.023), and a greater increase in peak VO2 (3.0 [0.9–4.3] vs. 0.3 [-0.6–1.8] mLO2·kg-1·min-1, p=0.015). Conclusion. Patients with HF treated with anakinra experience a transient increase in eosinophils, which is associated with ISR and greater improvement in peak VO2.(1)