Department of Pathology, The University of Texas Medical Branch, Galveston, Texas, USA.
Galveston National Laboratory, The University of Texas Medical Branch, Galveston, Texas, USA.
mBio. 2017 Sep 26;8(5):e00845-17. doi: 10.1128/mBio.00845-17.
Ebola virus (EBOV) disease (EVD) results from an exacerbated immunological response that is highlighted by a burst in the production of inflammatory mediators known as a "cytokine storm." Previous reports have suggested that nonspecific activation of T lymphocytes may play a central role in this phenomenon. T-cell immunoglobulin and mucin domain-containing protein 1 (Tim-1) has recently been shown to interact with virion-associated phosphatidylserine to promote infection. Here, we demonstrate the central role of Tim-1 in EBOV pathogenesis, as Tim-1 mice exhibited increased survival rates and reduced disease severity; surprisingly, only a limited decrease in viremia was detected. Tim-1 mice exhibited a modified inflammatory response as evidenced by changes in serum cytokines and activation of T helper subsets. A series of assays based on the Tim-1 expression profile on T cells demonstrated that despite the apparent absence of detectable viral replication in T lymphocytes, EBOV directly binds to isolated T lymphocytes in a phosphatidylserine-Tim-1-dependent manner. Exposure to EBOV resulted in the rapid development of a CD4 CD3 population, non-antigen-specific activation, and cytokine production. Transcriptome and Western blot analysis of EBOV-stimulated CD4 T cells confirmed the induction of the Tim-1 signaling pathway. Furthermore, comparative analysis of transcriptome data and cytokine/chemokine analysis of supernatants highlight the similarities associated with EBOV-stimulated T cells and the onset of a cytokine storm. Flow cytometry revealed virtually exclusive binding and activation of central memory CD4 T cells. These findings provide evidence for the role of Tim-1 in the induction of a cytokine storm phenomenon and the pathogenesis of EVD. Ebola virus infection is characterized by a massive release of inflammatory mediators, which has come to be known as a cytokine storm. The severity of the cytokine storm is consistently linked with fatal disease outcome. Previous findings have demonstrated that specific T-cell subsets are key contributors to the onset of a cytokine storm. In this study, we investigated the role of Tim-1, a T-cell-receptor-independent trigger of T-cell activation. We first demonstrated that Tim-1-knockout (KO) mice survive lethal Ebola virus challenge. We then used a series of assays to demonstrate that Ebola virus directly binds primary T cells in a Tim-1-phosphatidylserine-dependent manner. We noted that binding induces a cytokine storm-like phenomenon and that blocking Tim-1-phosphatidylserine interactions reduces viral binding, T-cell activation, and cytokine production. These findings highlight a previously unknown role of Tim-1 in the development of a cytokine storm and "immune paralysis."
埃博拉病毒（EBOV）病（EVD）是由炎症介质的爆发引起的免疫反应加剧所致，这些介质被称为“细胞因子风暴”。先前的报告表明，非特异性激活 T 淋巴细胞可能在这种现象中起核心作用。T 细胞免疫球蛋白和粘蛋白结构域包含蛋白 1（Tim-1）最近已被证明与病毒相关的磷脂酰丝氨酸相互作用以促进感染。在这里，我们证明了 Tim-1 在 EBOV 发病机制中的核心作用，因为 Tim-1 小鼠表现出存活率增加和疾病严重程度降低；令人惊讶的是，仅检测到病毒血症的有限下降。Tim-1 小鼠表现出炎症反应的改变，表现为血清细胞因子的变化和 T 辅助亚群的激活。一系列基于 T 细胞上的 Tim-1 表达谱的测定表明，尽管在 T 淋巴细胞中明显没有检测到可检测的病毒复制，但 EBOV 以磷脂酰丝氨酸-Tim-1 依赖性方式直接结合分离的 T 淋巴细胞。暴露于 EBOV 导致 CD4 CD3 群体的快速发展，非抗原特异性激活和细胞因子产生。EBOV 刺激的 CD4 T 细胞的转录组和 Western blot 分析证实了 Tim-1 信号通路的诱导。此外，对 EBOV 刺激的 T 细胞的转录组数据和上清液中细胞因子/趋化因子分析的比较分析突出了与 EBOV 刺激的 T 细胞和细胞因子风暴发作相关的相似性。流式细胞术揭示了中央记忆 CD4 T 细胞的几乎排他性结合和激活。这些发现为 Tim-1 在诱导细胞因子风暴现象和 EVD 发病机制中的作用提供了证据。埃博拉病毒感染的特征是炎症介质的大量释放，这已被称为细胞因子风暴。细胞因子风暴的严重程度与致命疾病结局一致相关。先前的研究表明，特定的 T 细胞亚群是细胞因子风暴发作的关键贡献者。在这项研究中，我们研究了 Tim-1 的作用，Tim-1 是 T 细胞激活的独立于 T 细胞受体的触发因素。我们首先证明了 Tim-1 敲除（KO）小鼠在致命的埃博拉病毒攻击下存活。然后，我们使用一系列测定来证明埃博拉病毒以 Tim-1-磷脂酰丝氨酸依赖性方式直接结合原代 T 细胞。我们注意到，结合诱导细胞因子风暴样现象，并且阻断 Tim-1-磷脂酰丝氨酸相互作用可降低病毒结合，T 细胞激活和细胞因子产生。这些发现突出了 Tim-1 在细胞因子风暴和“免疫麻痹”发展中的先前未知作用。
