Salusin-β contributes to vascular inflammation associated with pulmonary arterial hypertension in rats

OBJECTIVE:Inflammation is closely linked to pulmonary arterial hypertension (PAH). Salusin-β, a bioactive peptide, has been reported to participate in vascular inflammation. We therefore hypothesized that salusin-β contributes to monocrotaline (MCT)-induced PAH in rats. METHODS:Male Sprague-Dawley rats were treated with MCT (60 mg kg(-1), single intraperitoneal injection). Salusin-β expression in the lungs of the MCT-treated rats was evaluated using immunofluorescence staining, western blot, and real-time PCR. For salusin-β blockade assay, rats injected with MCT were given a chronic infusion of anti-salusin-β immunoglobulin G (IgG) (salusin-β blocker, 1.0 μg kg(-1) h(-1)) or isotype-matched control IgG. Four weeks after MCT+anti-salusin-β treatment, the effects of salusin-β blockade were determined using hemodynamics, western blot, real-time PCR, and immunohistochemical detection. The effect of salusin-β on human pulmonary arterial endothelial cell (HPAEC) function was detected by adhesion and tube formation experiments in vitro. RESULTS:Salusin-β expression was significantly increased in the lungs of the MCT-treated rats, and immunofluorescence results showed that salusin-β was predominantly expressed in pulmonary macrophages and vascular endothelial cells. Salusin-β blockade significantly ameliorated PAH by acting against pulmonary vascular remodeling, decreasing macrophage infiltration, and reducing pro-inflammatory cytokine expression and nuclear factor-kappa B (NF-κB) activity in the lungs of the MCT-treated rats. In addition, salusin-β could induce cell adhesion and accelerate angiogenesis by activating the NF-κB pathway and promoting pro-inflammatory cytokine expression in the cultured HPAECs. This effect was suppressed by addition of the NF-κB inhibitor, N-acetyl-L-cysteine. CONCLUSIONS:Salusin-β plays a crucial role in the development of MCT-induced PAH models.