Abstract 11079: Calcitonin Signaling Controls Disease-Induced Left Ventricular Remodeling

Abstract

Introduction: We recently discovered that the well-known thyroid hormone calcitonin (CT) is produced by atrialcardiomyocytes (CMs) and regulates atrial fibrogenesis and arrhythmia susceptibility via CT receptors (CTRs) inatrial cardiofibroblasts (CFs). Whether the CT-CTR system regulates ventricular function and structure isunknown and was the object of this study. Method and Results: Human studies were performed on left ventricular (LV) samples from 27 patients who hadcardiac surgery (Oxford, UK; ethical approval 18/SC/0404). Animal studies used 8-10 week-old male control(CTR flx/flx ; n=150) and CTR -/- (n=131) mice subjected to transverse aortic constriction (TAC) and myocardialinfarction (MI), with selected analyses in wild type mice (n=5). Cardiac function was assessed byechocardiography at baseline, 3 and 6 weeks post-TAC, and 1 and 4 weeks post-MI.Expression profiling detected CTR and CT mRNA (qPCR; Fig. A-B) and protein (immunoblotting) in human LVtissue and mouse LV CMs and CFs, with a higher CT abundance in CMs. CTR protein was decreased in LV tissue from patients with hypertension vs non-hypertensive controls (Fig. C).CTR deletion enhanced atrial and LV fibrosis (Masson’s Trichrome; Fig. D-E), significantly exacerbated post-TAC LV ejection fraction reduction by 15.2% (Fig. F), and atrial (by 23.7%, Fig. G) and LV dilation (by 19.9%),while increasing induced-AF duration by 6-fold (Fig. H) and inducibility by 15% vs post-TAC controls.In CTR -/- mice, acute MI produced greater fibrosis in the LV risk-region (by 18%; Fig. I), ejection fractionreduction (by 14%, Fig. J) vs CTR flx/flx controls. Mortality, atrial dilation and AF-inducibility were similar inCTR -/- and control MI-mice. Conclusion: CTR deletion in mice exacerbates adverse LV remodeling and dysfunction in clinically-relevantdisease models, pointing towards an important protective role of CT-CTR signaling in ventricular myocardium.