Abstract：
Oxidative damage and accumulation of extracellular matrix (ECM) components play a crucial role in the adverse outcome of cardiac hypertrophy. Evidence suggests that nuclear factor erythroid-derived factor 2 related factor 2 (Nrf2) can modulate oxidative damage and adverse myocardial remodeling. Daphnetin (Daph) is a coumarin obtained from the plant genus Daphne species that exerts anti-oxidative and anti-inflammatory properties. Herein, we investigated the roles of Daph in transverse aortic constriction (TAC)-induced cardiac hypertrophy and fibrosis in mice. TAC-induced alterations in cardiac hypertrophy markers, histopathological changes, and cardiac function were markedly ameliorated by oral administration of Daph in mice. We found that Daph significantly reduced the reactive oxygen species (ROS) generation, increased the nuclear translocation of Nrf2, and consequently, reinstated the protein levels of NAD(P)H quinone dehydrogenase1 (NQO1), heme oxygenase-1 (HO-1), and other antioxidants in the heart. Besides, Daph significantly inhibited the TAC-induced accumulation of ECM components, including α-smooth muscle actin (α-SMA), collagen I, collagen III, and fibronectin, and interfered with the TGF-β1/Smad2/3 signaling axis. Further studies revealed that TAC-induced terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) positive nuclei and the protein levels of Bax/Bcl2 ratio and cleaved caspase 3 were substantially decreased by Daph treatment. We further characterized the effect of Daph on angiotensin II (Ang-II)-stimulated H9c2 cardiomyoblast cells and observed that Daph markedly decreased the Ang-II induced increase in cell size, production of ROS, and proteins associated with apoptosis and fibrosis. Mechanistically, Daph alone treatment enhanced the protein levels of Nrf2, NQO1, and HO-1 in H9c2 cells. The inhibition of this axis by Si-Nrf2 transfection abolished the protective effect of Daph in H9c2 cells. Taken together, Daph effectively counteracted the TAC-induced cardiac hypertrophy and fibrosis by improving the Nrf2/HO-1 axis and inhibiting the TGF-β1/Smad2/3 signaling axis.
摘要：
细胞外基质（ECM）成分的氧化损伤和积累在心脏肥大的不良结局中起着至关重要的作用。有证据表明，核因子红系衍生因子2相关因子2（Nrf2）可以调节氧化损伤和不良心肌重塑。Daphnein（Daph）是从植物属Daphne物种获得的香豆素，具有抗氧化和抗炎特性。在这里，我们研究了Daph在横主动脉缩窄（TAC）诱导的小鼠心肌肥厚和纤维化中的作用。TAC诱导的心脏肥大标志物改变，组织病理学变化,小鼠口服Daph可显着改善心脏功能。我们发现Daph显着减少了活性氧（ROS）的产生，增加了Nrf2的核易位，因此，恢复NAD（P）H醌脱氢酶1（NQO1）的蛋白质水平，血红素加氧酶-1（HO-1），和心脏中的其他抗氧化剂。此外,Daph显著抑制TAC诱导的ECM成分的积累，包括α-平滑肌肌动蛋白（α-SMA），胶原蛋白I，胶原蛋白III，和纤连蛋白,并干扰TGF-β1/Smad2/3信号轴。进一步的研究表明，通过Daph处理，TAC诱导的末端脱氧核苷酸转移酶dUTP缺口末端标记（TUNEL）阳性细胞核以及Bax/Bcl2比率和裂解的半胱天冬酶3的蛋白质水平大大降低。我们进一步表征了Daph对血管紧张素II（Ang-II）刺激的H9c2心肌细胞的作用，并观察到Daph显着降低了Ang-II诱导的细胞大小增加，ROS的生产，以及与细胞凋亡和纤维化相关的蛋白质。机械上,Daph单独处理可提高H9c2细胞中Nrf2，NQO1和HO-1的蛋白质水平。Si-Nrf2转染对该轴的抑制消除了Daph在H9c2细胞中的保护作用。一起来看,Daph通过改善Nrf2/HO-1轴和抑制TGF-β1/Smad2/3信号轴，有效对抗TAC诱导的心肌肥大和纤维化。
