Inhibition of endocan attenuates monocrotaline-induced connective tissue disease related pulmonary arterial hypertension.

Connective tissue disease related pulmonary arterial hypertension (CTD-PAH) is characterized by vascular remodeling, endothelial dysfunction and inflammation. Endocan is a novel endothelial dysfunction marker. The aim of the present study was to investigate the role of endocan in CTD-PAH. Monocrotaline (MCT)-induced PAH rats were used as the CTD-PAH model. Short hairpin RNA packed in a lentiviral vector used to inhibit endocan expression was intratracheally instilled in rats prior to the MCT injection. Endocan was found to be increased in the serum and lung of MCT-induced PAH rats. Short hairpin RNA mediated knockdown of endocan significantly decreased right ventricular systolic pressure, attenuated pulmonary remodeling and inflammatory responses in the lung. In the in vitro study, tumor necrosis factor-α (TNF-α) exposure caused increased endocan expression in the primary cultured rat pulmonary microvascular endothelial cells (RPMECs). Endocan knockdown inhibited the permeability increase and adhesion molecules secretion in RPMECs induced by TNF-α. In addition, TNF-α induced MAPK activation was blocked when endocan gene was knocked down. These data demonstrate that endocan may play an important role in the development of CTD-PAH. This study provides novel evidence to better understand the pathogenesis of CTD-PAH, which may be beneficial for the treatment of this disease.