Grape seed proanthocyanidin extract attenuates airway inflammation and hyperresponsiveness in a murine model of asthma: Downregulating inducible nitric oxide synthase

Background: Allergic asthma is characterized by hyperresponsiveness and inflammation of the airway with increased expression of inducible nitric oxide synthase (iNOS) and overproduction of nitric oxide (NO). Grape seed proanthocyanidin extract (GSPE) has been proved to have antioxidant, anti-inflammatory and other pharmacological effects. Aims and objectives: The purpose of this study was to examine the role of GSPE on airway inflammation and hyperresponsiveness in a mouse model of allergic asthma. Methods: BALB/c mice, sensitized and challenged with OVA, were intraperitoneally injected with GSPE. HE staining and PAS staining were used to observe airway inflammation in lung tissue and airway mucus secretion, respectively. Quantification of cytokines in bronchoalveolar lavage fluid (BALF) and total serum immunoglobulin E (IgE) were detected by ELISA. The protein expression of iNOS was evaluated by immunohistochemistry and Western Blot analysis. Results: GSPE remarkably suppressed airway resistance, and reduced the total inflammatory cell and eosinophil counts in BALF. Treatment with GSPE significantly enhanced interferon (IFN)-γ level and decreased interleukin (IL)-4 and IL-13 levels in BALF and total IgE levels in serum. GSPE attenuated allergen-induced lung eosinophilic inflammation and mucus-producing goblet cells in the airway. The elevated iNOS expression observed in the OVA mice was significantly inhibited by GSPE. Conclusions: GSPE decreases the progression of airway inflammation and hyperresponsiveness by downregulating the iNOS expression, promising to be a potential in the treatment of allergic asthma.