Effects of shikonin on the proliferation and activation of T lymphocytes

Abstract

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 ([Ca2+]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 mRNA 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 [Ca2+]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.

Keywords

• psoriasis
• shikonin
• signal transduction pathway
• T lymphocyte activation
• treatment principle of cooling blood and detoxification