Effects of Shikonin on the Proliferation and Activation of T Lymphocytes

Objective: To investigate the effects of Chinese herbal monomer shikonin which has the function of cooling blood and detoxification on abnormally activated T lymphocyte and its related signal pathways and to elucidate the role of shikonin in the pathological state of psoriasis and its mechanism of treating psoriasis. Materials and Methods: Jurkat E6?1 T lymphocytes were activated with phorbol ester and ionomycin. The shikonin concentration of 0.5–2 μg/mL was applied to the cells, and the proliferation of T lymphocytes was detected by Cell Counting Kit?8 assay. Flow cytometry was used to measure CD69 expression on the cell membrane and intracellular free calcium ion concentration([Ca;]i); enzyme?linked immunosorbent assay was used to detect the levels of interleukin（IL）?2, interferon?γ（IFN?γ）, and（TNF?α） released by activated T lymphocytes; quantitative polymerase chain reaction and Western blot were used to observe the expression of nuclear transcription factor m RNA and protein, respectively. Results: Different concentrations of shikonin could significantly inhibit cell proliferation, CD69 expression, and secretion of Th1 cytokines. In addition, shikonin could effectively reduce the [Ca;]i and protein kinase C phosphorylation proteins. Besides that, shikonin could significantly reduce the nuclear transcription factor nuclear factor of activated T lymphocytes mRNA expression, downregulate c?Jun mRNA and protein expression, and inhibit NF?κB protein expression. All the above indicators show a certain dose–effect relationship. Conclusions: Shikonin can exert immune regulation by inhibiting the function of overactivated T lymphocytes. Hence, this study provides experimental basis for the mechanism and application prospect of shikonin in the treatment of psoriasis.