Protocatechuic acid attenuates angiotensin II‐induced cardiac fibrosis in cardiac fibroblasts through inhibiting the NOX4/ROS/p38 signaling pathway

Cardiac fibrosis plays a crucial role in the pathogenesis of myocardial infarction (MI). It has been found that differentiation of cardiac fibroblasts (CFs) into myofibroblasts is a major event in the process of cardiac fibrosis. In the present study, we aimed to investigate the effects of protocatechuic acid (PCA), a cardiac protective agent, on the CFs differentiation in vitro. The results showed that PCA exhibited inhibitory effects on the cell proliferation and migration in angiotensin II (Ang II)-induced CFs. PCA treatment suppressed the Ang II-induced expression of α-smooth muscle actin (α-SMA), which is a hallmark of myofibroblasts. In addition, the production of extracellular matrix (ECM) proteins, including type I collagen (Col I) and connective tissue growth factor (CTGF), were significantly decreased in the PCA-treated CFs. The Ang II-induced increased levels of matrix metalloproteinase (MMP)-2, and MMP-9 were reduced by PCA. Furthermore, PCA resulted in decrease in reactive oxygen species (ROS) generation, as well as the expressions of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase enzyme 4 (NOX4) and p-p38 in Ang II-induced CFs. These findings showed that PCA treatment prevented the Ang II-induced cardiac fibrosis by inhibiting the NOX4/ROS/p38 signaling pathway in vitro, suggesting that PCA might be a therapeutic agent for MI.