β2-adrenergic receptor autoantibodies alleviated myocardial damage induced by β1-adrenergic receptor autoantibodies in heart failure

Aims beta(1)-adrenergic receptor autoantibodies (beta(1)-AAs) and beta(2)-adrenergic receptor autoantibodies (beta(2)-AAs) are present in patients with heart failure (HF); however, their interrelationship with cardiac structure and function remains unknown. This study explored the effects of the imbalance between beta(1)-AAs and beta(2)-AAs on cardiac structure and its underlying mechanisms in HF. Methods and results Patients with left systolic HF who suffered from coronary heart disease (65.9%) or dilated cardiomyopathy (34.1%) were divided into New York Heart Association Classes I-II (n = 51) and Classes III-IV (n = 37) and compared with healthy volunteers as controls (n = 41). Total immunoglobulin G from HF patient serum comprising beta(1)-AAs and/or beta(2)-AAs were determined and purified for in vitro studies from neonatal rat cardiomyocytes (NRCMs). In addition, HF was induced by doxorubicin in mice. We observed that the increased ratio of beta(1)-AAs/beta(2)-AAs was associated with worsening HF in patients. Moreover, beta(2)-AAs from patients with HF suppressed the hyper-shrinking and apoptosis of NRCMS induced by beta(1)-AAs from some patients. Finally, beta(2)-AAs alleviated both myocardial damage and beta(1)-AAs production induced by doxorubicin in mice. Conclusion beta(2)-AAs were capable of antagonizing the effects imposed by beta(1)-AAs both in vitro and in vivo. The imbalance of beta(1)-AAs and beta(2)-AAs in patients with HF is a mechanism underlying HF progression, and the increasing ratio of beta(1)-AAs/beta(2)-AAs should be considered a clinical assessment factor for the deterioration of cardiac function in patients with HF.