Decreased autophagy: a major factor for cardiomyocyte death induced by β1-adrenoceptor autoantibodies.

Cardiomyocyte death is one major factor in the development of heart dysfunction, thus, understanding its mechanism may help with the prevention and treatment of this disease. Previously, we reported that anti-β1-adrenergic receptor autoantibodies (β1-AABs) decreased myocardial autophagy, but the role of these in cardiac function and cardiomyocyte death is unclear. We report that rapamycin, an mTOR inhibitor, restored cardiac function in a passively β1-AAB-immunized rat model with decreased cardiac function and myocardial autophagic flux. Next, after upregulating or inhibiting autophagy with Beclin-1 overexpression/rapamycin or RNA interference (RNAi)-mediated expression of Beclin-1/3-methyladenine, β1-AAB-induced autophagy was an initial protective stress response before apoptosis. Then, decreased autophagy contributed to cardiomyocyte death followed by decreases in cardiac function. In conclusion, proper regulation of autophagy may be important for treating patients with β1-AAB-positive heart dysfunction.