Effector CD4+ T cells can be classified by the cytokines they secrete, with T helper 1 (Th1) cells generating interferon (IFN)γ and Th17 cells secreting interleukin (IL)-17. Both Th1 and Th17 cells are strongly implicated in the initiation and chronicity of autoimmune diseases such as multiple sclerosis. The endoplasmic reticulum (ER) has been implicated as a potentially crucial site in regulating CD4+ T cell function. Secretory and transmembrane proteins are shuttled into the ER via the Sec61 translocon, where they undergo appropriate folding; misfolded proteins are retro-translocated from the ER in a p97-dependent manner. Here, we provide evidence that both processes are crucial to the secretion of inflammatory cytokines from effector CD4+ T cells. The pan-ER inhibitor eeeyarestatin-1 (ESI), which interferes with both Sec61 translocation and p97 retro-translocation, inhibited secretion of interferon (IFN)γ, interleukin (IL)-2 and tumor necrosis factor (TNF)α from Th1 cells in a dose-dependent manner. Selective inhibition of Sec61 by Apratoxin A (ApraA) revealed that ER translocation is crucial for Th1 cytokine secretion, while inhibition of p97 by NMS-873 also inhibited Th1 function, albeit to a lesser degree. By contrast, none of ESI, ApraA or NMS-873 could significantly reduce IL-17 secretion from Th17 cells. ApraA, but not NMS-873, reduced phosphorylation of Stat1 in Th1 cells, indicating the involvement of ER translocation in Th1 differentiation pathways. ApraA had modest effects on activation of the Th17 transcription factor Stat3, while NMS-873 had no effect. Interestingly, NMS-873 was able to reduce disease severity in CD4+ T cell-driven experimental autoimmune encephalomyelitis (EAE). Together, our data indicate that CD4+ T cell function, and Th1 cell function in particular, is dependent on protein translocation and dislocation across the ER.

中文翻译：

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跨内质网的蛋白质易位和逆向易位对炎症效应 CD4+ T 细胞功能至关重要

效应 CD4+ T 细胞可以根据它们分泌的细胞因子进行分类，T 辅助 1 (Th1) 细胞产生干扰素 (IFN)γ，Th17 细胞分泌白细胞介素 (IL)-17。Th1 和 Th17 细胞都与自身免疫性疾病（如多发性硬化症）的发生和慢性化密切相关。内质网 (ER) 被认为是调节 CD4+ T 细胞功能的潜在关键部位。分泌蛋白和跨膜蛋白通过 Sec61 转位子进入内质网，在那里进行适当的折叠；错误折叠的蛋白质以 p97 依赖性方式从内质网逆向易位。在这里，我们提供的证据表明，这两个过程对于效应 CD4+ T 细胞分泌炎性细胞因子至关重要。泛 ER 抑制剂 eeeyarestatin-1 (ESI)，干扰 Sec61 易位和 p97 逆向易位，以剂量依赖性方式抑制 Th1 细胞分泌干扰素 (IFN)γ、白细胞介素 (IL)-2 和肿瘤坏死因子 (TNF)α。Apratoxin A (ApraA) 对 Sec61 的选择性抑制表明，ER 易位对 Th1 细胞因子分泌至关重要，而 NMS-873 对 p97 的抑制也抑制了 Th1 功能，尽管程度较轻。相比之下，ESI、ApraA 或 NMS-873 均不能显着降低 Th17 细胞的 IL-17 分泌。ApraA，但不是 NMS-873，降低 Th1 细胞中 Stat1 的磷酸化，表明 ER 易位参与 Th1 分化途径。ApraA 对 Th17 转录因子 Stat3 的激活有适度影响，而 NMS-873 没有影响。有趣的是，NMS-873 能够降低 CD4+ T 细胞驱动的实验性自身免疫性脑脊髓炎 (EAE) 的疾病严重程度。总之，我们的数据表明 CD4+ T 细胞功能，尤其是 Th1 细胞功能，依赖于蛋白质跨内质网的易位和错位。