Neuropeptide Y promotes adipogenesis of human cardiac mesenchymal stromal cells in arrhythmogenic cardiomyopathy

Background: Arrhythmogenic Cardiomyopathy (AC) is a familial cardiac disease, mainly caused by mutations in desmosomal genes. AC hearts show fibro-fatty myocardial replacement, which favors stress-related life -threatening arrhythmias, predominantly in the young and athletes. AC lacks effective therapies, as its pathogenesis is poorly understood. Recently, we showed that cardiac Mesenchymal Stromal Cells (cMSCs) contribute to adipose tissue in human AC hearts, although the underlying mechanisms are still unclear. Purpose: We hypothesize that the sympathetic neurotransmitter, Neuropeptide Y (NPY), participates to cMSC adipogenesis in human AC. Methods: For translation of our findings, we combined in vitro cytochemical, molecular and pharmacologic assays on human cMSCs, from myocardial biopsies of healthy controls and AC patients, with the use of existing drugs to interfere with the predicted AC mechanisms. Sympathetic innervation was inspected in human autoptic heart samples, and NPY plasma levels measured in healthy and AC subjects. Results: AC cMSCs expressed higher levels of pro-adipogenic isotypes of NPY-receptors (i.e. Y1-R, Y5-R). Consistently, NPY enhanced adipogenesis in AC cMSCs, which was blocked by FDA-approved Y1-R and Y5-R antagonists. AC-associated PKP2 reduction directly caused NPY-dependent adipogenesis in cMSCs. In support of the involvement of sympathetic neurons (SNs) and NPY in AC myocardial remodeling, patients had elevated NPY plasma levels and, in human AC hearts, SNs accumulated in fatty areas and were close to cMSCs. Conclusions: Independently from the disease origin, AC causes in cMSCs a targetable gain of responsiveness to NPY, which leads to increased adipogenesis, thus playing a role in AC myocardial remodeling.