Aucubin Protects against TGFβ1-Induced Cardiac Fibroblasts Activation by Mediating the AMPKα/mTOR Signaling Pathway

Fibrosis is a key feature of various cardiovascular diseases and compromises cardiac systolic and diastolic performance. The lack of effective anti-fibrosis drugs is a major contributor to the increasing prevalence of heart failure. The present study was performed to investigate whether the iridoid aucubin alleviates cardiac fibroblast activation and its underlying mechanisms. Neonatal rat cardiac fibroblasts were incubated with aucubin (1, 10, 20, 50 mu M) followed by transforming growth factor beta 1 (TGF beta 1, 10ng/mL) stimulation for 24h. Fibrosis proliferation was measured by cell counting kit-8 assay. The differentiation of fibroblasts into myofibroblasts was determined by measuring the expression of beta-smooth muscle actin. Then, the expressions levels of cardiac fibrosis-related proteins in myofibroblasts were analyzed by western blot and real-time PCR to confirm the anti-fibrosis effect of aucubin. As a result, aucubin suppressed TGF beta 1-induced proliferation in fibroblasts and inhibited the TGF beta 1-induced activation of fibroblasts to myofibroblasts. In addition, aucubin further attenuated fibrosis-related protein expression in myofibroblasts. Furthermore, this protective effect was related to increased adenosine 5-monophosphate-activated protein kinase (AMPK) phosphorylation and decreased mammalian target of rapamycin (mTOR) phosphorylation, which was confirmed by an mTOR inhibitor (rapamycin), an AMPK agonist (AICAR) and an AMPK alpha inhibitor compound C. Collectively, our findings suggest that aucubin protects against TGF beta 1-induced fibroblast proliferation, activation and function by regulating the AMPK alpha/mTOR signal axis.