Group 1 Metabotropic Glutamate Receptor’s Influence on T Cells During Chronic Toxoplasma Infection

项目总结/摘要 弓形虫（Toxoplasma gondii，T.弓形虫）是世界上最有效的传染性病原体之一，感染 大约二十亿人。寄生虫在大脑神经元中的包囊导致终身慢性 感染在大脑内，促炎反应对于防止寄生虫重新激活至关重要。感染 免疫功能低下者导致致命的弓形虫脑炎，而免疫功能正常者则 持续的低度炎症，缺乏临床症状。这表明，有一个严格的监管， 对T.大脑中的弓形虫T细胞是主要的免疫细胞， 复发和寄生虫复制通过分泌效应分子如穿孔素和IFN-γ。 然而，人们对这些细胞在该组织中如何调节知之甚少。在慢性感染期间， 细胞外（EC）谷氨酸盐增加。高EC谷氨酸不是T.弓形虫感染，可发生 在多种病理过程中，但可能是组织特异性免疫细胞的重要环境信号。我们 假设这种富含谷氨酸的环境在T细胞功能和调节中起作用。 实验数据表明，来自T.弓形虫感染的大脑表达G蛋白偶联 代谢型谷氨酸受体（mGluR），mGluR 1和mGluR 5。这种表达在T细胞中富集 与次级淋巴衍生细胞相比，本项目旨在：1）定义第1组 在感染过程中，大脑中表达mGluR的T细胞，并确定是否存在功能差异 与外围相比。这将通过表征典型T细胞亚群的表面蛋白来完成， 测试效应分子的分泌，确定它们是否定位于大脑的不同区域， 在单细胞水平上表征转录谱; 2）确定1组mGluR如何调节T 细胞对感染的反应。这将通过追踪过继转移的mGluR缺陷T细胞来完成。 感染的野生型受体，并通过离体激活或抑制这些受体，然后测量 生存力、增殖、细胞因子产生和典型Gq分子的变化; 3）确定是否降低细胞因子的表达， 受感染大脑中的谷氨酸浓度将改变T细胞向中枢神经系统的募集情况。 系统（CNS）。这将通过表征mGluR表达性T细胞在免疫后募集到大脑来完成。 头孢曲松治疗，一种抗生素，以前在我们的实验室使用，以降低外源性谷氨酸在大脑中， 增加谷氨酸转运蛋白-1的表达。总的来说，这项提议将帮助我们了解组织是如何- 导出信号影响保护抗扰度。此外，我们从拟议的研究中了解到， 扩大到其他领域，如神经退行性疾病的研究，因为这些神经疾病中的一些不仅 具有谷氨酸改变的共性，但也具有向CNS募集T细胞的共性。

PROJECT SUMMARY/ABSTRACT Toxoplasma gondii (T. gondii) is one of the most effective transmissible pathogens in the world, infecting approximately two billion people. Encystment of the parasite in neurons in the brain results in a lifelong chronic infection. Within the brain, a pro-inflammatory response is essential to prevent parasite reactivation. Infection in the immunocompromised leads to lethal toxoplasmic encephalitis while in the immunocompetent, there is persistent low-grade inflammation which lacks clinical symptoms. This suggests that there is a tightly regulated inflammatory response to T. gondii in the brain. T cells are the dominant immune cell that control recrudescence and parasite replication through secretion of effector molecules such as perforins and IFN-γ. However, little is known on how these cells are regulated in this tissue. During chronic infection there is an increase in extracellular (EC) glutamate. High EC glutamate is not specific to T. gondii infection and can occur during multiple pathologies but may be an important environmental signal to tissue specific immune cells. We hypothesize that this glutamate-rich environment plays a role in T cell function and regulation. Preliminarily data demonstrate that T cells from the T. gondii -infected brain express the G-protein coupled metabotropic glutamate receptors (mGluR’s), mGluR1 and mGluR5. This expression is enriched in T cells recruited to the brain compared to secondary lymphoid derived cells. This project aims to: 1) define group 1 mGluR expressing T cells in the brain during infection, and determine if there is a functional difference compared to the periphery. This will be done by characterizing surface proteins for canonical T cell subsets, testing the secretion of effector molecules, defining if they localize to distinct regions of the brain, and characterizing the transcriptional profile at a single cell level; 2) determine how group 1 mGluR’s regulate T cells in response to infection. This will be done by tracking adoptively transferred mGluR-deficient T cells in an infected wild type recipient, and by activating or inhibiting these receptors ex vivo, followed by measuring changes in viability, proliferation, cytokine production, and canonical Gq molecules; 3) determine if lowering the glutamate concentrations in the infected brain will alter the T cell recruitment profile to the central nervous system (CNS). This will be done by characterizing mGluR expressing T cells recruited to the brain after ceftriaxone treatment, an antibiotic previously used in our lab to lower exogenous glutamate in the brain by increasing glutamate transporter-1 expression. Overall, this proposal will help us understand how tissue- derived signals influence protective immunity. Furthermore, what we learn from our proposed studies could be broaden to other fields such as neurodegenerative research, as some of these neurological maladies not only have a commonality of glutamate alteration, but also a recruitment of T cells to the CNS.