Docosahexaenoic acid inhibits monocrotaline-induced pulmonary hypertension via attenuating endoplasmic reticulum stress and inflammation

Endoplasmic reticulum (ER) stress and inflammation contribute to pulmonary hypertension (PH) pathogenesis. Previously, we confirmed that docosahexaenoic acid (DHA) could improve hypoxia-induced PH. However, little is known about the link between DHA and monocrotaline (MCT)induced PH. Our aims were, therefore, to evaluate the effects and molecular mechanisms of DHA on MCT-induced PH in rats. Rat PH was induced by MCT. Rats were treated with DHA daily in the prevention group (following MCT injection) and the reversal group (after MCT injection for 2 wk) by gavage. After 4 wk, mean pulmonary arterial pressure (mPAP), right ventricular (RV) hypertrophy index, and morphological and immunohistochemical analyses were evaluated. Rat pulmonary artery smooth muscle cells (PASMCs) were used to investigate the effects of DHA on cell proliferation stimulated by platelet-derived growth factor (PDGF)-BB. DHA decreased mPAP and attenuated pulmonary vascular remodeling and RV hypertrophy, which were associated with suppressed ER stress. DHA blocked the mitogenic effect of PDGF-BB on PASMCs and arrested the cell cycle via inhibiting nuclear factor of activated T cells-1 (NFATc1) expression and activation and regulating cell cycle-related proteins. Moreover, DHA ameliorated inflammation in lung and suppressed macrophage and T lymphocyte accumulation in lung and adventitia of resistance pulmonary arteries. These findings suggest that DHA could protect against MCT-induced PH by reducing ER stress, suppressing cell proliferation and inflammation.