Effects of Hovenia dulcis Thunb. extract and methyl vanillate on atopic dermatitis-like skin lesions and TNF-alpha/IFN-gamma-induced chemokines production in HaCaT cells

Abstract

Objectives Here, we hypothesized that Hovenia dulcis branch extract (HDB) and its active constituents ameliorates 2,4-dinitrochlorobenzene-induced atopic dermatitis (AD)-like skin lesions by modulating the T helper Th1/Th2 balance in NC/Nga mice and TNF-alpha- and IFN-gamma-induced production of thymus and activation-regulated chemokine (TARC) and macrophage-derived chemokine (MDC) in HaCaT cells. Methods HaCaT cells were stimulated by TNF-alpha/IFN-gamma in the presence of HDB and its constituents. TARC and MDC were measured by ELISA and RT-PCR. For the in-vivo study, oral feeding of HDB was performed for 5 weeks with 2,4dinitrochlorobenzene (DNCB) treatment every other day. The efficacy of HDB on parameters of DNCB-induced AD was evaluated morphologically, physiologically and immunologically. Key findings In-vitro studies showed that HDB and its constituents suppressed TNF-alpha/IFN-gamma-induced production of TARC and MDC in HaCaT cells by inhibiting MAPK signalling. In-vivo studies showed that HDB regulated immunoglobulin (Ig) E and immunoglobulin G2a (IgG2a) levels in serum and the expression of mRNA for Th1- and Th2-related mediators in skin lesions. Histopathological analyses revealed reduced epidermal thickness and reduced infiltration of skin lesions by inflammatory cells. Conclusion These results suggest that HDB inhibits AD-like skin diseases by regulating Th1 and Th2 responses in NC/Nga mice and in HaCaT cells.