Antiasthmatic activity and selective inhibition of type 2 helper T cell response by aqueous extract of semen armeniacae amarum

Semen armeniacae amarum (SAA) has long been used to control asthma in Korean traditional medicine. However, its antiasthmatic action still remains poorly understood. In the current study, effective mechanism of SAA was investigated in a mouse model of allergic asthma induced by repeated sensitization and intranasal challenge with OVA. Airway hyperreactivity (AHR) measured by beta-methacoline-induced airflow obstruction and airway recruitment of leukocytes including eosinophils were significantly reduced by oral treatment of SAA water extract. Level of interleukin (IL)-4, but not Interferon gamma (IFN-gamma), in the bronchoalveolar lavage fluid (BALF) also appeared considerably lower in SAA-treated mice than in controls. Collectively, these data show that SAA suppresses type 2 helper T cell (Th2), but not type 1 helper T cell (Th1), response. This hypothesis was supported further by the data of ex vivo cytokine production of peribronchial lymph node cells. Thus, oral administration of SAA attenuates asthmatic manifestations including AHR and airway inflammation, which possibly result from selective inhibition of Th2 response to allergen. Our data strongly suggest that SAA may be effectively applied to control other Th2-related diseases as well as allergic asthma.