Alginate Oligosaccharide Alleviates Monocrotaline-Induced Pulmonary Hypertension via Anti-Oxidant and Anti-Inflammation Pathways in Rats

Pulmonary arterial hypertension (PAH) is a serious and fatal cardiovascular disorder characterized by increased pulmonary vascular resistance and progressive pulmonary vascular remodeling. The underlying pathological mechanisms of PAH are multi-factorial and multi-cellular. Alginate oligosaccharide (AOS), which is produced by depolymerizing alginate, shows better pharmacological activities and beneficial effects. The present study was undertaken to investigate the effects and potential mechanisms of AOS-mediated alleviation of pulmonary hypertension. Pulmonary hypertension was induced in Sprague-Dawley rats by a single intraperitoneal injection of monocrotaline (MCT; 60 mg/kg). Five weeks after the injection of MCT, AOS (5, 10, and 20 mg-kg−1・d−1) was injected intraperitoneally for another three weeks. The results showed that AOS prevented the development of MCT-induced pulmonary hypertension and right ventricular hypertrophy in a dose-dependent manner. AOS treatment also prevented MCT-induced pulmonary vascular remodeling via inhibition of the TGF-β1/p-Smad2 signaling pathway. Furthermore, AOS treatment downregulated the expression of malondialdehyde, nicotinamide adenine dinucleotide phosphate oxidase, and pro-inflammatory cytokines, decreased macrophage infiltration, and upregulated the expression of anti-inflammatory cytokines. These findings indicate that AOS exerts anti-oxidative and anti-inflammatory effects in pulmonary arteries, which may contribute to the alleviation of pulmonary hypertension and pulmonary vascular remodeling.