Aloin alleviates pathological cardiac hypertrophy via modulation of the oxidative and fibrotic response

Aims: Pathological cardiac hypertrophy is a characteristic feature in many cardiovascular diseases (CVDs). Aloin is an anthraquinone glycoside from Aloe species, and the effect of aloin on cardiac hypertrophy and associated fibrotic changes have not been elucidated. This study investigated the effect of aloin against the isoproterenol (ISO)-induced cardiac hypertrophy in rats. Main methods: Cardiac hypertrophy experimental model was induced in rats by subcutaneous injection of ISO for 14 days. Meanwhile, the animals were administered orally with aloin at doses of 25 and 50 mg/kg/day. On the 15th day, cardiac echocardiography was performed, the heart was collected and subjected for histopathological, gene expression, and immunoblot studies. Additionally, the effect of aloin on ISO-induced hypertrophic changes in H9c2 cells was investigated. Key findings: Aloin markedly alleviated ISO-induced heart injury, reduced cardiac hypertrophy, improved cardiac function, and histological alterations in the heart. Mechanistically, aloin attenuated ISO-induced fibrosis via inhibition of the levels of collagen I, alpha-smooth muscle actin (alpha-SMA), fibronectin, transforming growth factor-beta (TGF-beta) and pSmad2/3 proteins in the heart. Aloin alleviated ISO-induced myocardial oxidative damage and upregulated the levels of antioxidant transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) proteins. Moreover, aloin treatment attenuated ISO-induced hypertrophic changes and the generation of reactive oxygen species (ROS) in H9c2 cells in vitro. Significance: Our findings demonstrated that aloin alleviated ISO-induced cardiac hypertrophy and fibrosis via inhibiting TGF-beta/pSmad2/3 signaling and restoring myocardial antioxidants, and therefore has promising therapeutic potential against cardiac hypertrophy and fibrosis.