Suppressive effect of Petasites japonicus extract on ovalbumin-induced airway inflammation in an asthmatic mouse model

Petasites japonicus extract has inhibitory properties on asthma and may be used as a potent therapeutic agent for allergic lung inflammation. Asthma is a disease marked by airway inflammation. Petasites japonicus (Pj) is known as an herb for treating asthma, oxidant stress and gastric ulcer in traditional Oriental medicine. In this study, the inhibitory effects of Pj extract on asthmatic responses were examined both in vitro and in vivo. The Pj extract was acquired from whole plants of Petasites japonicus using 80% ethanol. Cytotoxicity of the Pj extract on Jurkat cells and THP-1 cells was determined using MTT assay. ELISA was performed to determine the expression levels of cytokines, chemokines, and IgE. BALB/c mice were used for an OVA-induced asthmatic mouse model. Reactive oxygen species (ROS) production was stained with 2′,7′-dichlorofluorescein diacetate and measured by fluorescence-activated cell sorting analysis. The effects of the Pj extract on leukocyte infiltration and mucus production were determined using periodic acid-Schiff staining as well as hematoxylin and eosin staining. The Pj extract inhibits the increased release of interleukin (IL)-2, IL-4, IL-5, IL-13, and TNF-α due to house dust mite in Jurkat cells and blocks IL-6 expression in THP-1 cells without cytotoxicity. In the asthmatic mouse model, the Pj extract inhibits eosinophil infiltration, mucus hypersecretion, and IL-5 level in bronchoalveolar lavage (BAL) fluid, and it has a scavenging effect on ROS production of cells in BAL fluid. The Pj extract has suppressive properties for the pathogenesis of airway inflammation and may be used as a potent agent for the treatment of asthma.