PROJECT ABSTRACT Obesity is associated with a higher risk for the development of malignant ventricular tachyarrhythmias (VT), particularly under conditions of repolarization disorders and QT interval prolonging mechanisms (an established risk factor for VT), and sometimes tragically transitions to sudden cardiac death. In obesity, excess dietary fat in adipose tissues stimulates the release of immunomodulatory cytokines such as interleukin(IL)-6, leading to a state of chronic inflammation in patients. In the past decade, IL-6 trans-signaling has emerged as a powerful predictor of risk for VT. The first selective inhibitor of IL-6, olamkicept, has shown encouraging results in phase II clinical studies for inflammatory bowel disease. Nevertheless, the connection between IL-6 and VT remains undiscovered. The long-term goal is to help inform the development of therapeutically novel anti-cytokine drugs for the clinical treatment of life-threatening malignant VT. The overall objectives in this application are to (i) elucidate the molecular mechanism(s) by which IL-6 signaling triggers dramatic and arrhythmogenic electrical changes in vitro and (ii) determine in vivo anti-IL-6 signaling anti-arrhythmic efficacy using a guinea pig high-fat diet-induced inflammation model. Our central hypothesis is that over-activation of IL-6 trans-signaling triggers proarrhythmogenic changes in the rapidly activating delayed rectifier K channel (IKr) and calcium (Ca) handling in vitro and promotes lethal VT in vivo by promoting electrical disturbances in the ventricular myocardium. The rationale for this project is that a determination of the therapeutic potential of IL-6 signaling inhibition and associated cellular mechanisms is likely to reveal a strong mechanistic basis whereby new strategies to treat lethal ventricular arrhythmias in patients can be developed. The central hypothesis will be tested by pursuing two specific aims: 1) determine anti-arrhythmic effects of IL-6 signaling inhibition; and 2) identify the mechanism(s) of arrhythmogenesis by over-stimulation of IL-6 trans-signaling. Under the first aim, Langendorff perfused guinea pig hearts, and telemetered guinea pigs will be used to evaluate IL-6 trans-signaling-mediated electrical remodeling and inducibility of ventricular tachyarrhythmias and sudden cardiac death. For the second aim, guinea pig and obese/heart failure human epicardial adipose- tissue derived secretome, and guinea pig ventricular myocytes will be used to evaluate the effects IL-6 trans- signaling have on IKr biophysics and Ca handling, and the underlying mechanisms. Additionally, proven hyper- IL-6 and olamkicept methodologies and assays to evaluate the effects that loss-of-function phenotypes (anti- arrhythmic potential) have on obesity- and IL-6 trans-signaling-induced VT will be employed. The research proposed in this application is innovative, in the applicant’s opinion, because it focuses on pathological IL-6 trans-signaling and the potential of anti-IL-6 as an anti-arrhythmic in future anti-cytokine clinical trials. The proposed research is significant because it is expected to provide strong scientific justification for the continued development and future clinical trials of anti-cytokine drugs. Ultimately, such knowledge has the potential of offering opportunities of innovative therapies to treat VT.

PROJECT NARRATIVE The proposed research is relevant to public health because it focuses on the potential of an anti-interleukin-6 trans-signaling strategy to treat malignant ventricular arrhythmias while preserving the beneficial anti- inflammatory classical interleukin-6 arm. Once such strategies have been developed, there is the potential for a significant advance in anti-cytokine therapy for patients with life-threatening arrhythmias. Thus, the proposed research is relevant to the part of the NIH’s mission that pertains to enhancing health, and lengthening life.