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.