IL33 and heart failure: To shed light on the role of IL-1β and IL-33 signaling within the myocardium of heart failure patients, the expression levels of IL-1B, IL-1 receptors IL-1R1, IL-1R2 and IL-1RaP and of IL-33 and IL-1RL1 were determined via real-time quantitative PCR analysis (Figure 1).