Formononetin attenuated allergic diseases through inhibition of epithelial-derived cytokines by regulating E-cadherin.

Radix Astragali, has long been used to alleviate allergic diseases (ADs). Formononetin is one of the major active components in Radix Astragali, but its mechanism on ADs is not definitively known. The fluorescein isothiocyanate isomer-induced atopic contact dermatitis mouse model and poly I:C or lipopolysaccharide-treated HaCaT cells were used to examine thymic stromal lymphopoietin (TSLP)/interleukin (IL)-33 production and expression of E-cadherin. After administration of formononetin, TSLP/IL-33 levels decreased both in vitro and in vivo, while E-cadherin was increased in vivo and restored in vitro. Furthermore, small interference RNA silencing of E-cadherin resulted in elevated levels of TSLP, whereas the inhibitory effect of formononetin on TSLP was no longer observed. In addition, TSLP resulted in no detectable changes in delocalization or protein expression of E-cadherin in HaCaT cells. These results indicated that formononetin showed a protective effect in ADs, which was correlated with decreasing TSLP/IL-33 production via regulation of E-cadherin.