Catestatin alleviates PASMC phenotypic switching-mediated pulmonary arterial remodeling in a rat model of MCT-induced pulmonary arterial hypertension by promoting endothelium-derived no synthesis.

BACKGROUND: Enhancing the nitric oxide (NO) signaling pathway is an effective strategy for treating pulmonary arterial hypertension (PAH). Previous research has found that Catestatin (CST) exerts a negative inotropic effect by upregulating NO production. However, the effect of CST on PAH remains unclear.

METHODS: In vivo, PAH was induced in rats by monocrotaline (MCT) injection. After MCT administration, continuous CST treatment was applied to the experimental group. At study conclusion, echocardiographic, hemodynamic, and histological assessments were performed. In vitro, the effects of CST on rat pulmonary arterial endothelial dysfunction and phenotypic switching of rat pulmonary arterial smooth muscle cells (rPASMC) under PAH-like conditions were investigated. The role of NO in rPASMC phenotypic switching was also explored.

RESULTS: In vivo experiments demonstrated that CST significantly improved right heart structure and function in rats with PAH, reduced pulmonary arterial pressure, and alleviated remodeling of the right ventricle and pulmonary arteries. These effects were likely mediated by upregulation of the eNOS/cGMP/PKG pathway. In vitro, CST promoted endothelial NO synthesis via the PI3K/Akt/eNOS pathway, but had no significant impact on the proliferation or migration of rPASMCs. In contrast, exogenous NO effectively inhibited rPASMC phenotypic switching by arresting the cell cycle at the G0/G1 phase.

CONCLUSION: CST enhances endothelial NO synthesis through the PI3K/Akt/eNOS pathway, which subsequently acts on rPASMCs to inhibit their phenotypic switching via the NO/cGMP/PKG signaling pathway, thereby alleviating pulmonary arterial remodeling in PAH.