Anti-allergic effects of Vernonia amygdalina leaf extracts in hapten-induced atopic dermatitis-like disease in mice

Background: Atopic dermatitis (AD) is a chronic inflammatory skin disease characterized by pruritic and eczematous skin lesions. In this study, AD-like disease was induced in NC/Nga mice so as to evaluate the antiallergic effects of Vernonia amygdalina leaf extracts (VAM). Methods: Forty NC/Nga mice were purchased for each of the two protocols (prophylactic and curative) of the study. Mice were randomly divided in groups of five or six after sensitization with 5% trinitrochlorobenzene (TNCB): aqueous extracts (VAM1), methanolic extracts (VAM2), hydrocortisone (HCT), buffer for the control (TNCB) and the normal mice (NORM) groups. Results: As for HCT, VAM1 and VAM2-pretreated mice showed significantly lower number of scratching behavior episodes (p < 0.01; vs. TNCB) following TNCB challenge. In addition, VAM1, VAM2 exerted a significant inhibitory effect on the development of AD skin symptoms (vs. TNCB group; p < 0.001), the production of IgE, TNF-alpha (p < 0.05), IL-5 and IFN-gamma (p < 0.01) (vs. TNCB group) and on the increase in ear thickness (p < 0.05) in prophylactic protocol. In the AD curative protocol, topical VAM1, VAM2 markedly improved skin lesions such as erythema/hemorrhage (p < 0.05), scaling/dryness, erosion/excoriation (p < 0.01) (vs. TNCB mice). Furthermore, a significant decrease in ear thickness was noted in VAM1, VAM2, HCT groups (vs. TNCB group; p < 0.05) as well as the serum total IgE, MCP-1 (p < 0.01) and eotaxin (p < 0.05). VAM2 also improved chronic eczema dermatitis skin symptoms in a patient. Conclusions: Results from this report suggest that VAM extracts, known as ERK pathway inhibitor, prevent and improve atopic/eczema dermatitis syndrome.