Grape seed proanthocyanidin extract attenuates airway inflammation and hyperresponsiveness in a murine model of asthma by downregulating inducible nitric oxide synthase.

: 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, antitumor, anti-inflammatory, and other pharmacological effects. The purpose of this study was to examine the role of GSPE on airway inflammation and hyperresponsiveness in a mouse model of allergic asthma. BALB/c mice, sensitized and challenged with ovalbumin (OVA), were intraperitoneally injected with GSPE. Administration of GSPE remarkably suppressed airway resistance and reduced the total inflammatory cell and eosinophil counts in BALF. Treatment with GSPE significantly enhanced the interferon (IFN)- γ level and decreased interleukin (IL)-4 and IL-13 levels in BALF and total IgE levels in serum. GSPE also 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. In conclusion, GSPE decreases the progression of airway inflammation and hyperresponsiveness by downregulating the iNOS expression, promising to have a potential in the treatment of allergic asthma.