Leukocyte Activation and Migration in Autoimmune Encephalomyelitis

 描述（由申请人提供）：我们研究项目的总体目标是了解自身免疫性疾病（如多发性硬化症（MS））期间白细胞活化和迁移的分子机制。大量的膜受体可以启动白细胞活化和/或迁移，其包括抗原受体、趋化因子受体和整联蛋白。虽然这些受体与多种细胞外配体（第一信使）结合，但它们产生的常见细胞内第二信使是PIP 3（磷脂酰肌醇3，4，5-三磷酸）; PIP 3反过来通过与数十种调节基因表达和/或细胞骨架重塑的效应蛋白（如蛋白激酶AKT，BTK和PDK 1）结合来指导白细胞活化和迁移。本申请的灵感来自于我们最近的发现，即共同脂质第二信使PIP 3的发生和功能由其TNFAIP 8（肿瘤坏死因子-α-诱导蛋白8）家族的“专业”转移蛋白控制。TNFAIP 8家族具有特异性疏水腔，其被磷酸肌醇如PIP 3的酰基链组成性占据，并且它是PIP 3的唯一已知的转移蛋白家族。我们首先从实验性自身免疫性脑脊髓炎（EAE）小鼠脊髓中克隆了TIPE 2（TNFAIP 8-like 2）基因，发现它优先由白细胞表达。然后，我们产生了TIPE 2缺陷小鼠，发现它们对EAE有显著的抵抗力。出乎意料的是，TIPE 2缺陷的髓鞘特异性TH 1和TH 17细胞对髓鞘抗原高度敏感，但在向CNS的迁移中具有内在缺陷。因此，我们假设TNFAIP 8家族通过控制介导活化和迁移的常见脂质第二信使的发生和功能来赋予髓鞘特异性T细胞的致脑炎性。在其不存在的情况下，脂质第二信使的活化诱导的激增破坏了引导细胞迁移的内部PIP 3“罗盘”，导致产生不能定向迁移的过度活跃的非致脑炎性TH 1和TH 17细胞。将使用遗传学、免疫学和生物化学方法在鼠和人系统（包括MS）中测试该理论。具体而言，我们将确定（I）TIPE 2和TNFAIP 8调节髓鞘特异性T细胞活化的机制，以及（II）TIPE 2和TNFAIP 8调节自身免疫性脑脊髓炎期间白细胞迁移的机制。

 DESCRIPTION (provided by applicant): The overall objective of our research program is to understand the molecular mechanisms of leukocyte activation and migration during autoimmune diseases such as multiple sclerosis (MS). A large number of membrane receptors can initiate leukocyte activation and/or migration, which include antigen receptors, chemokine receptors, and integrins. While these receptors bind to a diverse array of extracellular ligands (first messengers), a common intracellular second messenger generated by them is PIP3 (phosphatidylinositol 3,4,5-trisphosphate); PIP3 in turn directs leukocyte activation and migration by binding to dozens of effector proteins (such as protein kinases AKT, BTK, and PDK1) that regulate gene expression and/or cytoskeleton remodeling. This application is inspired by our recent discovery that the genesis and function of the common lipid second messenger PIP3 are controlled by its "professional" transfer proteins of the TNFAIP8 (tumor necrosis factor-α-induced protein 8) family. The TNFAIP8 family possesses a specific hydrophobic cavity that is constitutively occupied by the acyl chains of phosphoinositides such as PIP3, and it is the only known transfer protein family of PIP3. We initially cloned the TIPE2 (TNFAIP8-like 2) gene from spinal cord of mice with experimental autoimmune encephalomyelitis (EAE) and found that it was preferentially expressed by leukocytes. We then generated TIPE2-deficient mice and found that they were significantly resistant to EAE. Unexpectedly, TIPE2-deficient myelin-specific TH1 and TH17 cells were hyper-sensitive to myelin antigens but had an intrinsic defect in migration into CNS. We therefore hypothesize that TNFAIP8 family confers the encephalitogenicity of myelin-specific T cells by controlling the genesis and function of common lipid second messengers that mediate both activation and migration. In its absence, the activation-induced surge of lipid second messengers destroys the internal PIP3 "compass" that guides cell migration, leading to the generation of hyper-active non-encephalitogenic TH1 and TH17 cells not capable of directional migration. This theory will be tested in both murine and human systems (including MS) using genetic, immunological, and biochemical approaches. Specifically, we will determine (I) the mechanism through which TIPE2 and TNFAIP8 regulate myelin-specific T cell activation, and (II) the mechanism through which TIPE2 and TNFAIP8 regulate leukocyte migration during autoimmune encephalomyelitis.