Adiponectin up-regulates the decrease of myocardial autophagic flux induced by β₁ -adrenergic receptor autoantibody...

Cardiomyocytes autophagy is essential for maintaining cardiac function. Our previous studies have found that β₁ -adrenergic receptor autoantibody (β₁ -AA) induced the decreased myocardial autophagic flux, which resulted in cardiomyocyte death and cardiac dysfunction. And other studies demonstrated that β₁ -AA induced the decrease of AMPK phosphorylation, the key hub of autophagy pathway, while adiponectin up-regulated autophagic flux mediated by AMPK. However, it is not clear whether adiponectin improves the inhibition of myocardial autophagic flux induced by β₁ -AA by up-regulating the level of AMPK phosphorylation. In this study, it has been confirmed that β₁ -AA induced the decrease of AMPK phosphorylation level in both vivo and vitro. Moreover, pretreatment of cardiomyocytes with AMPK inhibitor Compound C could further reduce the autophagic flux induced by β₁ -AA. Adiponectin deficiency could aggravate the decrease of myocardial AMPK phosphorylation level, autophagic flux and cardiac function induced by β₁ -AA. Further, exogenous adiponectin could reverse the decline of AMPK phosphorylation level and autophagic flux induced by β₁ -AA and even reduce cardiomyocyte death. While pretreated with the Compound C, the adiponectin treatment did not improve the decreased autophagosome formation, but still improved the decreased autophagosome clearance induced by β₁ -AA in cardiomyocytes. This study is the first time to confirm that β₁ -AA could inhibit myocardial autophagic flux by down-regulating AMPK phosphorylation level. Adiponectin could improve the inhibition of myocardial autophagic flux induced by β₁ -AA partly dependent on AMPK, so as to provide an experimental basis for the treatment of patients with β₁ -AA-positive cardiac dysfunction.