Inhibition of the T cell receptor (TCR) pathway represents an effective strategy for the treatment of T cell-mediated inflammatory and autoimmune diseases. To identify natural compounds that could inhibit inflammatory T cell responses, we screened 13 sesquiterpene lactones, including achillin, arglabin, argolide, argracin, 3β-hydroxyarhalin, artesin, artemisinin, estafiatin, grosheimin, grossmisin, leucomisine, parthenolide, and taurine, for their ability to modulate activation-induced Ca2+ mobilization in Jurkat T cells. Five of the compounds (arglabin, grosheimin, argracin, parthenolide, and estafiatin) inhibited anti-CD3-induced mobilization of intercellular Ca2+ ([Ca2⁺]i) in Jurkat cells, with the most potent being parthenolide and argacin (IC50 = 5.6 and 6.1 μM, respectively). Likewise, phosphorylation of extracellular signal-regulated kinase (ERK) 1/2 in activated Jurkat cells was inhibited by these five compounds, with the most potent being parthenolide and estafiatin (IC50 = 13.8 and 15.4 μM, respectively). These compounds also inhibited ERK1/2 phosphorylation in primary human T cells and depleted intracellular glutathione. In contrast, none of the sesquiterpene lactones inhibited ERK1/2 phosphorylation in HL60 cells transfected with N-formyl peptide receptor 2 (FPR2) and stimulated with the FPR2 peptide agonist WKYMVM, indicating specificity for T cell activation. Estafiatin, a representative sesquiterpene lactone, was also profiled in a cell-based phosphokinase array for 43 kinase phosphorylation sites, as well as in a cell-free competition binding assay for its ability to compete with an active-site directed ligand for 95 different protein kinases. Besides inhibition of ERK1/2 phosphorylation, estafiatin also inhibited phosphorylation of p53, AMPKα1, CREB, and p27 elicited by TCR activation in Jurkat cells, but it did not bind to any of 95 kinases evaluated. These results suggest that arglabin, grosheimin, agracin, parthenolide, and estafiatin can selectively inhibit initial phases of TCR activation and may be natural compounds with previously undescribed immunotherapeutic properties.

中文翻译：

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天然倍半萜内酯 arglabin、grosheimin、agracin、小白菊内酯和 estafiatin 抑制 T 细胞受体 (TCR) 激活

抑制 T 细胞受体 (TCR) 通路代表了治疗 T 细胞介导的炎症和自身免疫性疾病的有效策略。为了鉴定可以抑制炎症性 T 细胞反应的天然化合物，我们筛选了 13 种倍半萜内酯，包括 achillin、arglabin、argolide、argracin、3β-hydroxyarhalin、artesin、artemisinin、estafiatin、grosheimin、grosmisin、leucomisine、parthenolide，以及它们的调节 Jurkat T 细胞中激活诱导的 Ca2+ 动员的能力。五种化合物（arglabin、grosheimin、argracin、parthenolide 和 estafiatin）抑制抗 CD3 诱导的 Jurkat 细胞中细胞间 Ca2+ ([Ca2⁺]i) 的动员，其中最有效的是小白菊内酯和 argacin (IC50 = 5.6 6.1 μM，分别）。同样地，这五种化合物可抑制活化的 Jurkat 细胞中细胞外信号调节激酶 (ERK) 1/2 的磷酸化，其中最有效的是小白菊内酯和 estafiatin（IC50 分别为 13.8 和 15.4 μM）。这些化合物还抑制原代人类 T 细胞中的 ERK1/2 磷酸化并耗尽细胞内谷胱甘肽。相比之下，在用 N-甲酰肽受体 2 (FPR2) 转染并用 FPR2 肽激动剂 WKYMVM 刺激的 HL60 细胞中，没有一种倍半萜内酯能抑制 ERK1/2 磷酸化，表明 T 细胞活化的特异性。Estafiatin 是一种代表性倍半萜内酯，也在基于细胞的磷酸激酶阵列中分析了 43 个激酶磷酸化位点，以及在无细胞竞争结合试验中与活性位点定向配体竞争 95 种不同蛋白激酶的能力。除了抑制 ERK1/2 磷酸化外，estafiatin 还抑制由 Jurkat 细胞中 TCR 激活引起的 p53、AMPKα1、CREB ​​和 p27 的磷酸化，但它不与评估的 95 种激酶中的任何一种结合。这些结果表明 arglabin、grosheimin、agracin、小白菊内酯和 estafiatin 可以选择性地抑制 TCR 激活的初始阶段，并且可能是具有以前未描述的免疫治疗特性的天然化合物。