Inhibitory effects of astragaloside IV on ovalbumin-induced chronic experimental asthma.

Astragaloside IV, a new cycloartane-type triterpene glycoside extract of Astragalus membranaceus Bunge, has been identified for its potent immunoregulatory, antiinflammatory, and antifibrotic actions. Here we investigated whether astragaloside IV could suppress the progression of airway inflammation, airway hyperresponsiveness, and airway remodeling in a murine model of chronic asthma. BALB/c mice sensitized to ovalbumin (OVA) were chronically challenged with aerosolized OVA for 8 weeks. Astragaloside IV was orally administered at a dose of 50 mg x kg-1 x day-1 during each OVA challenge. Astragaloside IV treatment resulted in significant reduction of eosinophilic airway inflammation, airway hyperresponsiveness, interleukin (IL)-4 and IL-13 levels in bronchoalveolar lavage fluid, and total immunoglobulin E levels in serum. Furthermore, astragaloside IV treatment markedly inhibited airway remodeling, including subepithelial fibrosis, smooth muscle hypertrophy, and goblet cell hyperplasia. In addition, the expression of transforming growth factor-beta1 in the lung was also reduced by astragaloside IV. These data indicate that astragaloside IV may mitigate the development of characteristic features in chronic experimental asthma.