Anti-allergic effects of PG102, a water-soluble extract prepared from Actinidia arguta, in a murine ovalbumin-induced asthma model

Abstract

Background Asthma is a chronic inflammatory disease of the lung and its incidence has been increasing around the world. We previously reported that oral administration of a water-soluble extract prepared from Actinidia arguta, code-named PG102, could modulate the level of Th1 and Th2 cytokines and suppress the production of immunoglobulin E (IgE) in the ovalbumin (OVA)-immunized murine model as well as in the in vitro cell culture system, and furthermore could significantly improve dermatitis conditions in the NC/Nga murine model. These data suggested that PG102 might have therapeutic effects in a broad range of allergic diseases. Objective To assess the possible anti-allergic effects of PG102 in the OVA-induced murine asthma model. Methods The quality of PG102 was standardized, using its effects on the production of IgE, IL-5, and IL-13, in in vitro cell culture systems. To test effects on asthma, BALB/c mice were orally administrated with PG102, followed by OVA sensitization and challenge to induce asthmatic symptoms. Airway hyperresponsiveness (AHR), bronchoalveolar lavage fluid, serum, and lung tissue were analysed by using various methods. Results PG102 could decrease the level of IgE, IL-5, and IL-13 in in vitro cell culture systems with IC(50) being 1.12-1.43 mg/mL. PG102 could ameliorate asthmatic symptoms, including AHR and eosinophilia in the lungs. Such improvement of asthmatic symptoms by PG102 was accompanied by the down-regulation of IL-5 and IgE. In PG102-treated mice, high level expression of heme oxygenase-1, a potent anti-inflammatory enzyme, was observed in alveolar inflammatory cells, while the mRNA levels of foxp3, TGF-beta 1, and IL-10, important markers for regulatory T cells, were also up-regulated in the lung tissue. Conclusions PG102 may have potential as a safe and effective reagent for the prevention or treatment of asthma.