TNFGAMMA EFFECTS ON BLOOD BRAIN BARRIER PERMEABILITY

描述：(改编自申请者摘要)：肿瘤坏死 肿瘤坏死因子-α是炎症反应时释放的一种细胞因子。 身体中的事件。中枢神经系统肿瘤坏死因子-α水平的升高 在多发性硬化症、细菌性疾病等情况下观察的系统 脑膜炎、病毒感染和脑缺血表明细胞因子 可能参与了这些疾病的发病机制。一个主要的细胞 肿瘤坏死因子-a的靶点是内皮细胞，在那里凝血活性增加， 观察细胞黏附性和血管通透性。的确，外生性 注射肿瘤坏死因子-a会显著增加血脑中的含量 屏障(BBB)渗透性。因此，通过以下途径了解这些机制 哪种肿瘤坏死因子-α可引起脑微血管通透性改变 形成血脑屏障的内皮细胞，可能提供对原因的洞察和 中枢神经炎性事件的有效治疗 系统。拟议的研究将检验肿瘤坏死因子-a对血脑屏障的影响。 两个不同级别的渗透性。第一，原代培养的牛脑 微血管内皮细胞(BBMEC)将作为一种体外模型 血脑屏障检查与通透性影响有关的细胞因素 肿瘤坏死因子-α的表达。需要检验的假设是，肌动蛋白应激的抑制 细胞内细丝的形成将阻止BBMEC单层的增加 用肿瘤坏死因子-α观察通透性。体外培养的具体目标 研究将评估1)Rho介导的抑制作用 GTP结合蛋白，2)环核苷酸信号的改变 途径，以及3)花生四烯酸代谢的抑制 肿瘤坏死因子-α诱导的肌动蛋白细丝形成和BBMEC单层改变 渗透性。其次，将评估肿瘤坏死因子-a对血脑屏障的影响。 活着。活体研究的假设是血脑屏障的变化 在脑部炎症条件下观察到的通透性是 与释放的肿瘤坏死因子-a的量直接相关。在这些研究中， 微透析探针将被植入大鼠的大脑皮层。这个 该提案体内部分的具体目标是：1)确定 皮质给药后肿瘤坏死因子-α和肿瘤坏死因子的量效关系 血脑屏障通透性增加，以及2)内源性释放 脑组织注射细菌毒素或脑血流后产生的肿瘤坏死因子-a 闭塞伴血脑屏障通透性改变。微透析探头将被 用于将外源性肿瘤坏死因子-a输送到皮质中的特定部位以及 采样内源性释放的肿瘤坏死因子-α。总而言之，拟议的研究将 更好地了解肿瘤坏死因子-a的作用机制 对血脑屏障渗透性的影响。

DESCRIPTION: (Adapted from Applicant's Abstract): Tumor necrosis factor-alpha (TNF-a) is a cytokine released in response to inflammatory events in the body. The increased levels of TNF-a in the central nervous system observed in conditions such as multiple sclerosis, bacterial meningitis, viral infections and brain ischemia suggest that the cytokine may be involved in the pathogenesis of these diseases. A major cellular target for TNF-a is the endothelium, where increases in coagulant activity, cell adhesiveness and vascular permeability are observed. Indeed, exogenous administration of TNF-a produces significant increases in blood-brain barrier (BBB) permeability. Therefore, understanding the mechanisms through which TNF-a produces changes in the permeability of brain microvessel endothelial cells that form the BBB, may provide insight into the cause and effective treatment of inflammatory events within the central nervous system. The proposed studies will examine the effects of TNF-a on BBB permeability on two distinct levels. First, primary cultured bovine brain microvessel endothelial cells (BBMEC) will be used as an in vitro model of the BBB to examine the cellular factors involved in the permeability effects of TNF-a. The hypothesis to be examined is that inhibition of actin stress filament formation in the cells will prevent increases in BBMEC monolayer permeability observed with TNF-a. The specific aims for the in vitro studies will be to evaluate the effects that 1) inhibition of Rho-mediated GTP binding proteins, 2) alterations in cyclic nucleotide signaling pathways, and 3) inhibition of arachidonic acid metabolism has on TNF-alpha-induced changes in actin filament formation and BBMEC monolayer permeability. Secondly, the effects of TNF-a on BBB will be evaluated in vivo. The hypothesis for the in vivo studies is that changes in BBB permeability observed under inflammatory conditions in the brain are directly correlated to the amount of TNF-a released. For these studies, microdialysis probes will be implanted into the cortex of rats. The specific aims for the in vivo portion of the proposal are to 1) determine the dose-response relationship between cortically administered TNF-a and increases in BBB permeability, and 2) correlate the endogenous release of TNF-a following cortical injection of bacterial toxin or cerebral blood flow occlusion with changes in BBB permeability. Microdialysis probes will be used to deliver exogenous TNF-a to specific sites in the cortex as well as sampling endogenously released TNF-a. Together, the proposed studies will provide a better understanding of the mechanisms involved in TNF-a effects on BBB permeability.