Anti-inflammatory effect of Lonicera japonica in proteinase-activated receptor 2-mediated paw edema

Background: Lonicera japonica (Caprifoliaceae) has long been used for treatment of infectious diseases. In the present study, the anti-inflammatory effects of L. japonica water extract (AELJ) were investigated in proteinase-activated receptor 2 (PAR2)-mediated mouse paw edema. Methods: Paw edema was induced by injection of trypsin or trans-cinnamoyl-LIGRLO-NH₂ (tc-NH₂) into hindpaw of mice. AELJ (10, 50, 100, and 200 mg/kg) was orally administered 1 h before induction of inflammation. Results: At doses of 50, 100 and 200 mg/kg, the AELJ showed significant inhibition of both change in paw thickness and vascular permeability. The AELJ (100 mg/kg) also significantly inhibited PAR2 agonists-induced myeloperoxidase (MPO) activity and tumor necrosis factor (TNF)-α expression in paw tissue. Conclusion: The present study demonstrated that AELJ has an anti-inflammatory action for PAR2-mediated paw edema.