Anti-inflammatory effects of Capparis ecuadorica extract in phthalic-anhydride-induced atopic dermatitis of IL-4/Luc/CNS-1 transgenic mice

Context The natural products derived from Capparis ecuadorica H.H. Iltis (Capparaceae) could have great potential for anti-inflammation since they inhibited the inflammatory response in lipopolysaccharide (LPS)‐stimulated RAW 264.7 cells. Object This study investigated the anti-inflammatory effects and related mechanism of methanol extract of C. ecuadorica leaves (MCE) during atopic dermatitis (AD) responses. Materials and methods Alterations in the phenotypical markers for AD, luciferase signal, iNOS‐mediated COX‐2 induction pathway, and inflammasome activation were analysed in non-Tg (n = 5) and 15% phthalic anhydride (PA) treated IL-4/Luc/CNS-1 transgenic (Tg) HR1 mice (n = 5 per group), subsequent to treatment with acetone-olive oil (AOO), vehicle (DMSO) and two dose MCE (20 and 40 mg/kg) three times a week for 4 weeks. Results MCE treatment reduced the intracellular ROS level (48.2%), NO concentration (7.1 mmol/L) and inflammatory cytokine expressions (39.1%) in the LPS-stimulated RAW264.7 cells. A significant decrease was detected for ear thickness (16.9%), weight of lymph node (0.7 mg), IgE concentration (1.9 µg/mL), and epidermal thickness (31.8%) of the PA + MCE treated Tg mice. MCE treatment induced the decrease of luciferase signal derived from the IL-4 promoter and the recovery of the IL-4 downstream regulator cytokines. PA + MCE treated Tg mice showed decreasing infiltration of mast cells (42.5%), iNOS-mediated COX‐2 induction pathway, MAPK signalling pathway and inflammasome activation in the ear tissue. Conclusions These findings provide the first evidence that MCE may have great potential to suppress chemical-induced skin inflammation through the suppression of IL-4 cytokine and the iNOS-mediated COX‐2 induction pathway, and activation of inflammasome.