Proanthocyanidin from Grape Seed Extract Inhibits Airway Inflammation and Remodeling in a Murine Model of Chronic Asthma

Asthma is characterized by airway inflammation and airway remodeling. Our previous study revealed that grape seed proanthocyanidin extract (GSPE) could inhibit asthmatic airway inflammation and airway hyper-responsiveness by down-regulation of inducible nitric oxide synthase in a murine model of acute asthma. The present study aimed to evaluate GSPE's effects on airway inflammation and airway remodeling in a chronic asthmatic model. BALB/c mice were sensitized with ovalbumin (OVA) and then were challenged three times a week for 8 weeks. Airway responsiveness was measured at 24 h after the last OVA challenge. HE staining, PAS staining, and Masson staining were used to observe any airway inflammation in the lung tissue, airway mucus secretion, and subepithelial fibrosis, respectively. The cytokines levels in the lavage fluid (BALF) in addition to the total serum immunoglobulin E (IgE) levels were detected by ELISA. Furthermore, lung collagen contents, α-smooth muscle actin (α-SMA), and transforming growth factor-β1 (TGF-β1) expression in the airway were assessed by hydroxyproline assay, immunohistochemistry, and Western blot analysis, respectively. GSPE administration significantly suppressed airway resistance as well as reduced the amount of inflammatory cells, especially the eosinophil count, in BALF. Additionally, the GSPE treatment markedly decreased interleukin (IL)-4, IL-13, and vascular endothelial growth factor (VEGF) levels in BALF in addition to the total serum IgE levels. A histological examination demonstrated that GSPE significantly ameliorated allergen-induced lung eosinophilic inflammation and decreased PAS-positive epithelial cells in the airway. The elevated hydroxyproline contents, lung α-SMA contents, and TGF-β1 protein expression that were observed in the OVA mice were also inhibited by GSPE. In conclusion, GSPE could inhibit airway inflammation and airway remodeling in a murine model of chronic asthma, thus providing a potential treatment for asthma.