Anti-inflammatory and immunomodulatory mechanisms of artemisinin on contact hypersensitivity.

Artemisinin (Art) is a sesquiterpene trioxane lactone from Artemisia annua L., which has been shown to affect immune responses. However, the underlying mechanism remains elusive. In this study, we examined the anti-inflammatory and immunomodulatory effects of Art in a mouse model of contact hypersensitivity (CHS), a T-cell-mediated cutaneous inflammatory reaction. The data showed that topical administration of Art could suppress CHS response and Con A-induced T cell proliferation effectively. Further experiments indicated that Art induced the generation of regulatory T cells (Tregs) and impaired the phosphorylation of AKT, associated with the up-regulation of p38 MAPK activation. Moreover, Art also exerted a strikingly inhibitory effect on IL-17 production, and diminished the level of IL-6 paralleled with an enhancement of TGF-β, which effects were coupled with a significant reduction of STAT3 activation. These data reveal that Art could effectively block CHS response in mice by inducing the generation of Tregs and suppressing the development of Th17, indicating the potential of Art to be applied as an effective therapeutic agent for treating immune-related diseases.