Peucedanum japonicum extract attenuates allergic airway inflammation by inhibiting Th2 cell activation and production of pro-inflammatory mediators.

ETHNOPHARMACOLOGICAL RELEVANCE: The root of Peucedanum japonicum Thunberg is traditionally used to treat coughs, colds, headache and inflammatory diseases in Korea and Japan. Its effects on allergic lung inflammation have not been investigated. AIM OF THE STUDY: To investigate the anti-asthmatic effects of Peucedanum japonicum extract (PJE) using a murine model of asthma and a lipopolysaccharide (LPS)-stimulated macrophage cell line. MATERIALS AND METHODS: Mice underwent two rounds of sensitization with ovalbumin 1 week apart followed by four intranasal ovalbumin challenges on days 13-16. The control group received saline only. Two ovalbumin-sensitized groups were orally administered vehicle or PJE (200mg/kg) 5 days a week starting 1 week before the first ovalbumin sensitization. The third group was orally administered the asthma medication Montelukast (10mg/kg) on days 12-16. All animals were sacrificed on day 17. The lungs were assessed for histological features, inflammatory cell infiltration, Th2 cell activation and GATA-binding protein-3 (GATA-3) expression. The bronchoalveolar lavage fluid (BALF) was assessed for type 2 cytokine levels. The effect of PJE on the in vitro Th2 polarization of naïve CD4+ splenocytes and the production of pro-inflammatory mediators and cytokines by LPS-stimulated RAW 264.7 cells was evaluated. RESULTS: PJE treatment inhibited OVA-induced inflammatory cell infiltration, eosinophilia, Th2 activation, and GATA-3 expression in the lung, reduced the interleukin (IL)-5 and IL-13 levels in BALF, down-regulated Th2 activation in vitro, and inhibited the macrophage production of inducible nitric oxide, cyclooxygenase-2, tumor necrosis factor-α, and IL-6. CONCLUSION: PJE attenuated allergic airway inflammation by inhibiting Th2 cell activation and macrophage production of inflammatory mediators. Peucedanum japonicum may be candidate therapy for allergic lung inflammation.

Reduced allergic lung inflammation by root extracts from two species of Peucedanum through inhibition of Th2 cell activation.

ETHNOPHARMACOLOGICAL EVIDENCE: Peucedani Radix (PR), the root of Peucedanum praeruptorum Dunn (PPD) or Peucedanum decursivum (Miq.) Maxim. (PDM), has long been used in Korea to eliminate sputum, relieve cough, and reduce bronchus contraction. Furthermore, these therapeutic strategies are recognized as general and effective methods in western medicine as well as traditional Korean medicine. AIM OF THE STUDY: To determine and compare the anti-inflammatory effects of PPD extracts (PPDE) and PDM extracts (PDME) on allergic lung inflammation, using in vivo OVA-induced airway inflammation in mice and in vitro primary cell culture systems. MATERIALS AND METHODS: Eight-week-old female C57BL/6 mice were placed into four groups (n=4 per group): saline control, OVA-induced allergic lung inflammation with vehicle, or PPDE (200mg/kg) or PDME (200mg/kg) treatment. PR extracts (PRE) were administered from 1 week before 1st OVA sensitization to the day before sacrifice. Mice were sacrificed 18h after last OVA intra-nasal challenge followed by histological and biochemical analyses. RESULTS: Inflammatory phenotypes were alleviated with oral administration of PRE. PRE treatment decreased mucus production in airway epithelium, inflammatory cell number, eosinophilia, type 2 cytokines, and histamine in bronchoalveolar lavage fluid (BALF). Mice with PRE administration showed diminished activated CD4 T cell (CD4+CD25+ cell) and GATA-3 level in the lung. In addition, PRE treatment reduced Th2 cell activation in vitro, using Th2 polarization system. CONCLUSION: Our findings indicate that the anti-inflammatory effects of PRE arise from reduced Th2 cell activation and validate the clinical use of PR in traditional Korean medicine.