Department of Infection, Immunity and Cardiovascular disease, The Medical School, University of Sheffield, Sheffield S10 2RX, UK.
Department of Dermatology, Royal Hallamshire Hospital, Sheffield S10 2JF, UK.
Int J Environ Res Public Health. 2018 Dec 15;15(12):2882. doi: 10.3390/ijerph15122882.
Alopecia areata (AA) is associated with Interferon- γ (IFN-γ) mediated T-lymphocyte dysfunction and increased circulating Interleukine-17 (IL-17) levels. Epigallocatechin-3-gallate (EGCG) specifically inhibits IFN-γ pathways and unlike Janus Kinase 1 and 2 (JAK1/JAK2) inhibitors (tofacitinib, ruxolitinib), EGCG is safer, more cost-effective, and is a topically active agent. Our objective is to test the mode of action of EGCG in vitro and ex vivo using HaCat, Jurkat cell lines, and peripheral blood mononuclear cells (PBMCs) of AA patients and healthy controls (HCs), respectively.
distribution of T helper cells (Th1, Th17), and cytotoxic cells (CD8) in PBMCs isolated from 30 AA patients and 30 HCs was investigated by flowcytomterty. In vitro treatment of HaCat and Jurkat cells with 40 μm EGCG for 48 h was performed to measure the level of phosphorylation of signal transducer and activator of transcription protein STAT1, and replicated in ex vivo model using PBMCs of AA patients.
Interestingly, 40 μm EGCG is capable of completely inhibiting phosphorylation of STAT1 after 48 h in HaCat and Jurkat cells and ex vivo in PBMCs of AA patients. Based on QPCR data, the action of EGCG on p-STAT1 seems to be mediated via downregulation of the expression of JAK2 but not JAK1 leading to the inhibition of human leukocyte antigens (HLA-DR and HLA-B) expression probably via IRF-1. On the other hand, AA patients have significantly increased levels of Th1, Th17, and CD8 cells and the production of IFN-γ and IL-17 by PBMCs in AA patients was significantly higher compared to HC; = 0.008 and = 0.006, respectively. Total numbers of CD8+ cells were not significantly different between treated and untreated samples. However, CD8+ cells with positive Natural killer group 2 member D (NKG2D) transmembrane receptor (CD8+ NKG2D+ subset) was significantly reduced when PBMCs were treated with 20 μm EGCG for 48 h.
These results suggest that EGCG has a synergistic action that inhibits expression of HLA-DR and HLA-B molecules via the IFN-γ pathway to maintain immune privilege in HF; also it reduces CD8+ NKG2D+ subset.
斑秃（AA）与干扰素-γ（IFN-γ）介导的 T 淋巴细胞功能障碍和循环白细胞介素-17（IL-17）水平升高有关。表没食子儿茶素没食子酸酯（EGCG）特异性抑制 IFN-γ 途径，与 Janus 激酶 1 和 2（JAK1/JAK2）抑制剂（托法替尼、鲁索利替尼）不同，EGCG 更安全、更经济有效，且具有局部活性。我们的目的是分别使用 HaCat、Jurkat 细胞系和 AA 患者及健康对照（HC）的外周血单核细胞（PBMC）在体外和离体检测 EGCG 的作用机制。
通过流式细胞术检测 30 例 AA 患者和 30 例 HC 分离的 PBMC 中 Th1、Th17 和细胞毒性细胞（CD8）的分布。用 40 μm EGCG 体外处理 HaCat 和 Jurkat 细胞 48 h，测量信号转导和转录激活蛋白 STAT1 的磷酸化水平，并在 AA 患者的 PBMC 中进行离体模型复制。
有趣的是，40 μm EGCG 能够完全抑制 HaCat 和 Jurkat 细胞以及 AA 患者 PBMC 中的 STAT1 磷酸化 48 h。基于 QPCR 数据，EGCG 对 p-STAT1 的作用似乎是通过下调 JAK2 的表达而不是 JAK1 介导的，从而抑制人类白细胞抗原（HLA-DR 和 HLA-B）的表达，可能通过 IRF-1。另一方面，AA 患者的 Th1、Th17 和 CD8 细胞水平显著升高，AA 患者 PBMC 产生的 IFN-γ 和 IL-17 也显著高于 HC；分别为 0.008 和 0.006。治疗和未治疗样本之间的 CD8+细胞总数没有显著差异。然而，当 PBMC 用 20 μm EGCG 处理 48 h 时，CD8+细胞中阳性自然杀伤组 2 成员 D（NKG2D）跨膜受体（CD8+NKG2D+亚群）的数量显著减少。
这些结果表明，EGCG 通过 IFN-γ 途径具有协同作用，抑制 HLA-DR 和 HLA-B 分子的表达，以维持 HF 中的免疫豁免；它还减少了 CD8+NKG2D+亚群。
