NK cells in CNS inflammation and autoimmunity

项目概述：自然杀伤细胞（NK）是一种大的颗粒状淋巴细胞，通过细胞溶解活性和细胞因子分泌发挥作用，是先天免疫系统的重要组成部分。本课课组长期以来一直对NK细胞在自身免疫性疾病中的生物学功能感兴趣，特别是它们在中枢神经系统（CNS）炎症和自身免疫中的作用，如多发性硬化症（MS）及其动物模型实验性自身免疫性脑脊髓炎（EAE）。初步数据和相关文献提示，MS/EAE的起始可能源于先天免疫系统和适应性免疫系统细胞（包括NK细胞）之间的相互作用。为了测试这种可能性，我们开发了几种细胞和遗传方法来系统地和在中枢神经系统中操纵NK细胞，并研究了这些细胞影响中枢神经系统炎症程度和对髓鞘抗原自身免疫的能力。我们证明了使用抗nk1.1 mAb在所有器官系统中NK细胞的系统性耗损，或通过趋化因子受体CX3CR1的种系缺失选择性地减少NK细胞向中枢神经系统的归巢，导致单核淋巴细胞浸润到中枢神经系统，脱髓鞘，以及中枢神经系统髓磷脂反应性Th17的优先扩张。相反，通过NK细胞上IL-2受体的参与，NK细胞的扩增显著减弱了CNS，但没有减弱外周Th17细胞的反应。进一步的研究表明，NK细胞位于中枢神经系统的小胶质细胞附近，可以杀死小胶质细胞。当NK细胞被耗尽或不能回到中枢神经系统时，小胶质细胞扩大并产生大量的Th17极化细胞因子。此外，NK细胞的缺失促进了Th17谱系特异性转录因子Rorc和STAT3的激活，这种激活依赖于小胶质细胞。基于这些初步研究，我们建议剖析NK细胞介导的EAE保护的细胞机制。我们的中心假设是NK细胞控制炎症中枢神经系统中的小胶质细胞，并且NK细胞/小胶质细胞相互作用可以抑制髓磷脂反应性Th-17细胞并保护中枢神经系统免受自身免疫。为了验证这一假设，我们将：1)剖析中枢神经系统中NK细胞与小胶质细胞之间的相互作用，并确定NK细胞对小胶质细胞的细胞溶解活性的机制；2)确定NK细胞/小胶质细胞相互作用对中枢神经系统髓磷脂反应性CD4+ Th17细胞的产生、维持和功能的影响；3)测试基于nk的治疗方法对中枢神经系统炎症和自身免疫的保护作用。

DESCRIPTION (provided by applicant): NK cells in CNS inflammation and autoimmunity Project Summary: Natural killer (NK) cells are large, granular lymphocytes that operate through cytolytic activity and cytokine secretion, and represent an important component of the innate immune system. Our group has long been interested in understanding the biological functions of NK cells in autoimmune diseases, particularly their role in inflammation and autoimmunity in the central nervous system (CNS) such as multiple sclerosis (MS) and its animal model experimental autoimmune encephalomyelitis (EAE). Preliminary data and relevant literature suggest that the initiation of MS/EAE may stem from the interplay between cells of the innate and adaptive immune systems, including NK cells. To test this possibility, we developed several cellular and genetic approaches to manipulate NK cells systemically and in the CNS, and investigated the capacity of these cells to impact the magnitude of CNS inflammation and autoimmunity to myelin antigens. We demonstrated that the systemic depletion of NK cells in all organ system using an anti-NK1.1 mAb, or selectively reduced the homing of NK cells to the CNS through a germ-line deletion of the chemokine receptor CX3CR1, leads to pronounced mononuclear lymphocyitic infiltration into the CNS, demyelination, and preferential expansion of CNS myelin- reactive Th17. Conversely, the expansion of NK cells via the engagement of the IL-2 receptor on NK cells significantly attenuated the CNS, but not peripheral Th17 cell responses. Further investigations revealed that NK cells reside in proximity to microglia in the CNS, and that can kill microglia. When NK cells were depleted or were unable to home to the CNS, microglia expanded and produced large amounts of Th17 polarizing cytokines. Also, the absence of NK cells promoted the activation of the Th17 lineage-specific transcription factors Rorc and STAT3 in a manner that was dependent on microglia. Based on these preliminary studies, we propose to dissect the cellular mechanism governing NK cell-mediated protection from EAE. Our central hypothesis is that NK cells control microglia in the inflamed CNS, and that NK cell/microglia interactions can inhibit myelin-reactive Th-17 cells and protect against CNS autoimmunity. To test this hypothesis, we will: 1) Dissect the interactions between NK cells and microglia in the CNS and identify the mechanism responsible for the cytolytic activity of NK cells against microglia; 2) Define the impact of NK cell/microglia interactions on the generation, maintenance and function of myelin-reactive CD4+ Th17 cells in the CNS; 3) Test NK-based therapeutic approaches for the protection from CNS inflammation and autoimmunity.