Peucedanum japonicum extract attenuates allergic airway inflammation by inhibiting Th2 cell activation and inflammatory mediators

Abstract

BackgroundPeucedanum japonicum Thunb is traditionally used to treat coughs, colds, headaches and inflammatory diseases in Korea and Japan. However, the effects of Peucedanum japonicum on allergic lung inflammation have not been investigated. The aim of this study was to investigate the anti‐asthmatic effects of Peucedanum japonicum extract (PJE) in ovalbumin (OVA)‐induced asthmatic C57BL6 mice and lipopolysaccharide (LPS)‐stimulated RAW264.7 cells. First, we evaluated the effects of PJE on airway inflammation in OVA‐induced asthmatic mice. Next, we investigated whether PJE inhibited the activation of Th2 cells both in vivo and in vitro, and identified inflammation related proteins in LPS‐stimulated RAW 264.7 cells.Materials and methodsOVA was used to sensitize and challenge the airway of the mice, and PJE was orally administrated. We evaluated cell numbers, production of Th2 cell‐related cytokines in bronchoalveolar lavage fluid, histopathological features, and the levels of GATA‐binding protein‐3 (GATA‐3) in the lung. In addition, Th2 cell activation both in the lung and among primary cultured splenocytes was evaluated by Fluorescence‐activated cell sorting (FACS) analysis. Levels of inflammatory mediators and cytokines were determined in LPS‐stimulated RAW264.7 cells.ResultsPJE inhibited the OVA‐induced asthmatic response by reducing airway inflammation, and levels of Th2 cell related cytokines (IL‐5 and IL‐13). PJE inhibited the activation of Th2 cells both in vivo and in vitro via inactivation of CD4+ T cells, blockade of GATA‐3 expression, and reduction of the frequency of IL‐13‐producing cells after stimulation with phorbol 12‐myristate 13‐acetate (PMA) and ionomycin. Furthermore, PJE down regulated inflammatory mediators (iNOS and COX‐2) and proinflammatory cytokines (TNF‐α, and IL‐6) in RAW264.7 cells.ConclusionsThese results demonstrated that PJE inhibited the OVA‐induced asthmatic response by reducing airway inflammation. Consequently, PJE attenuates allergic airway inflammation by inhibiting Th2 cell activation and inflammatory mediators. These results indicate that Peucedanum japonicum is useful to treat allergic lung inflammation.Support or Funding InformationThis research was supported by grants for Evaluation of effectiveness of alternative herbal medicine resources (K14416 and K15411) from Korea Institute of Oriental Medicine (KIOM).