Curcumin inhibits proliferation of interleukin-22-treated HaCaT cells.

The interleukin (IL)-23/IL-17A/IL-22 cytokine axis plays a critical role in the pathogenesis of psoriasis, wherein IL-22 effects on epidermal alternations by inhibiting differentiation and inducing keratinocyte proliferation. In this study, we investigated effects of curcumin on IL-22-induced proliferation in a human keratinocyte cell line (HaCaT) in vitro experiment. The HaCaT cells growth was measured by a Cell Counting Kit-8. The cyclin D1 and cyclin E was detected by real-time RT-PCR and weatern blot. The STAT3 and phosphorylation of STAT3 was tested by weatern blot also. Our results show that curcumin exhibited a significant anti-proliferation effect on HaCaT cells, even in the presence of IL-22. Since STAT3 is crucial for IL-22 signal transduction, we examined the level of phosphorylation of STAT3 in all of the experimental groups. As expected, curcumin inhibited IL-22 induced phosphorylation of STAT3; furthermore, curcumin down regulated cyclin D1 and cyclin E. We can reach a conclusion that curcumin can suppress the proliferation of keratinocytes even with IL-22 treatment. Therefore, we have confidence in future curcumin research about psoriasis treatment.