Effect of Ephedra-Licorice on Th2 Allergic Contact Dermatitis Through Inhibiting Expression of TSLP

OBJECTIVE To investigate the effect and mechanism of ephedra-licorice drug pair on Th2 allergic contact dermatitis (ACD) model mice. METHODS Th2 ACD model and early phase of ACD model were established on BALB/c mice by using different concentrations of fluorescein isothiocyanate(FITC). HE staining was used to observe the histopathological changes of ears in mice. Ear swelling of mice were measured. The levels of Th2 cytokines and thymic stromal lymphocytes were measured by enzyme-linked immunosorbent assay (ELISA) were detected by real-time quantitative PCR (qPCR). The expressions of TSLP mRNA were detected by Poly (I∶ C) and TNF-α stimulated HaCaT cells. RESULTS In Th2 type ACD model， compared with the model group， ephedra-licorice 2.34g/kg and 7.02g/kggroups significantly inhibited ear swelling in mice and decreased inflammatory cell infiltration in the ear tissue. Both doses of ephedra-licorice group significantly reduced the level of IL-4 in the ear homogenate， and ephedra-licorice 7.02g/kg group significantly reduced IL-13 levels. Compared with the model group， ephedra-licorice significantly reduced the mRNA and protein levels of TSLP in the early stage of Th2 ACD model. In vitro， ephedra-licorice and the main monomers of ephedra and licorice also inhibited the secretion of TSLP. CONCLUSION Ephedra-licorice can inhibit allergic inflammation and its mechanism may be through the reduction of TSLP secretion.