Effects of Catalpa ovata stem bark on atopic dermatitis-like skin lesions in NC/Nga mice

Ethnopharmacological relevance: The stem bark of Catalpa ovata has been used as a traditional herbal medicine for the treatment of various inflammatory diseases such as itching and scabies. Aim of the study: In the present study, we investigated the anti-AD effects of Catalpa ovata stem bark on Dermatophagoides farinae-induced AD in a NC/Nga mouse AD model. We determined dermatitis score, histology, IgE, cytokines, and chemokines related to hypersensitive immune responses in AD. The mechanism of action was also investigated using HaCaT cells. Materials and methods: We investigated the topical effects of Catalpa ovata stem bark on AD-like skin lesions in NC/Nga mice. Five category-experiments were performed, including assessment of dermatitis score; histological analysis of dorsal skin lesions; quantitative measurement of serum total IgE; quantitative measurement of cytokines (IL-1 beta, IL-4, IL-5, IL-6, IL-13, TNF-alpha) from dorsal tissue; and RT-PCR analysis of for TSLP and TARC mRNA expression in HaCaT cells. Results: The clinical dermatitis score was significantly lower in Catalpa ovata extract (CUE) groups than in the control group. Histological analysis showed that CUE inhibited hypertrophy and hyperkeratosis of the epidermis, intracellular edema, and reduced the infiltration of inflammatory cells. CUE significantly inhibited serum total IgE; Th2 cytokines IL-4, IL-5 and IL-13; pro-inflammatory cytokines IL-1 beta, 16 and TNF-alpha; the Th2 chemokine TARC and the pro-Th2 cytokine TSLP. Conclusion: These results demonstrate that Catalpa ovata stem bark may be a useful external medicine for treatment of AD. Further investigation is necessary to determine appropriate CUE dosage and to evaluate the safety of this medicinal herb. (C) 2012 Elsevier Ireland Ltd. All rights reserved.