Targeting the BBB to treat CNS inflammation

项目2将确定如何靶向分子，调节渗透性和极性， 中枢神经系统（CNS）内皮屏障影响神经炎症，通过 多发性硬化症（MS）小鼠模型的新型神经成像模式。我们已经表明 MS病变中的内皮细胞表现出极性改变，显示出近腔趋化因子 CXCL 12沿管腔表面异常沿着。腔外CXCL 12通常用于限制 白细胞进入，而CXCL 12的腔表达与增加的活化相关 其信号受体CXCR 4在浸润性白细胞上的表达。我们发现， CXCL 12受体，CXCR 7（也由CNS内皮表达），是一种重要的调节因子， 白细胞通过CXCL 12从近腔表面内化进入。在初步研究中， 我们还发现，通过S1 P2的1-磷酸鞘氨醇（S1 P）信号传导干扰了近腔神经元的活动， CXCL 12的表达，然后破坏免疫豁免。因此，具有靶向缺失的小鼠 或给予特异性拮抗剂JTE-013，显示白细胞迁移减少 进入中枢神经系统实质我们假设，细胞膜极性的改变， CNS内皮屏障处的CXCL 12促进白细胞捕获和迁移到CNS中， 有助于建立复发缓解型CNS疾病周期 自身免疫我们已经确定了几种调节这一过程的分子， 逆转定位信号CXCL 12的顶基表达。在本提案中，我们将 检查CXCR 7和S1 P2在CNS中淋巴细胞运输和炎症中的作用 使用包括双光子活体内的新型成像方式的自身免疫性疾病 显微镜和纵向使用扩散基光谱成像（DBSI）， 区分和定量活小鼠中的细胞结构和水肿（见项目1）， 尸检的人MS患者和对照CNS组织的检查。 我们预计DBSI比Gd增强对炎症更敏感，包括在 设置不太深刻的血脑屏障改变。来确定 内皮细胞和免疫细胞（Th 1对Th 17）的相互作用和BBB完整性的丧失，我们将 直接比较使用活体成像与DBSI和Gd增强的结果， 动物为了阐明内皮细胞极性和定位信号的机制， 通过与炎症细胞的相互作用诱导，我们将利用体外和原位方法， 人体组织因此，目标1将确定CXCR 7介导的CXCL 12的内化是否 在EAE期间需要Th 1相对于Th 17细胞的浸润。目标2将确定S1 P2- 介导的内皮细胞极性逆转导致T细胞捕获和进入增加， EAE和Aim 3将检测CXCR 7和S1 PR 2活化与T细胞增殖的关系。 在MS的BBB迁移。项目2的实验设计将定义DBSI如何 确定的细胞结构和水肿变化响应于不同程度的BBB异常 和细胞浸润。

Project 2 will determine how targeting molecules that regulate permeability and polarity at central nervous system (CNS) endothelial barriers impacts neuroinflammation, as assessed via novel neuroimaging modalities with murine models of multiple sclerosis (MS). We have shown that endothelium in MS lesions exhibits altered polarity, displaying the abluminal chemokine CXCL12 aberrantly along luminal surfaces. Abluminal CXCL12 normally serves to limit leukocyte entry whereas luminal expression of CXCL12 is associated with increased activation of its signaling receptor CXCR4 on infiltrating leukocytes. We showed that the scavenging CXCL12 receptor, CXCR7 (also expressed by CNS endothelium), is a critical regulator of leukocyte entry via internalization of CXCL12 from abluminal surfaces. In preliminary studies, we have also found that sphingosine 1-phosphate (S1P) signaling via S1P2 disturbs abluminal expression of CXCL12, which then disrupts immune privilege. Thus, mice with targeted deletion of S1P2 or administered a specific antagonist, JTE-013, show reduced migration of leukocytes into the CNS parenchyma during EAE. We hypothesize that alterations in membrane polarity of CXCL12 at CNS endothelial barriers promote leukocyte capture and migration into the CNS, contributing to the establishment of disease cycles in relapsing-remitting forms of CNS autoimmunity. We have identified several molecules that regulate this process, leading to reversal of apicobasal expression of the localizing cue, CXCL12. In this proposal, we will examine the roles of CXCR7 and S1P2 in lymphocyte trafficking and inflammation in CNS autoimmune disease using novel imaging modalities including two-photon intravital microscopy and longitudinally using Diffusion Basis Spectrum Imaging (DBSI), which distinguishes and quantitates cellularity and edema in live mice (see Project 1) and examination of autopsied human MS patient and control CNS tissues. We expect DBSI to be more sensitive than Gd enhancement to inflammation, including in the setting of less profound blood-brain barrier alterations. To determine the relationships between endothelial and immune cell (Th1 versus Th17) interactions and loss of BBB integrity, we will directly compare results utilizing intravital imaging to DBSI and Gd enhancement in the same animals. To address mechanisms by which endothelial cell polarity and localizing cues are induced by interactions with inflammatory cells, we will utilize in vitro and in situ approaches with human tissues. Thus, Aim 1 will determine whether CXCR7-mediated internalization of CXCL12 requires infiltration with Th1 versus Th17 cells during EAE. Aim 2 will determine whether S1P2- mediated reversal of endothelial cell polarity leads to increased T cell capture and entry during EAE, and Aim 3 will examine the relationship between CXCR7 and S1PR2 activation and T cell migration at the BBB in MS. The experimental design of Project 2 will define how DBSI determined cellularity and edema changes responding to various degrees of BBB abnormality and cell infiltration in EAE mice.