Mechanistic Role of Monomeric GTPases in Experimental Autoimmune Neuritis

描述（由申请人提供）：炎症性周围神经病变在美国和世界范围内是一个相当大的社会和经济负担。炎症性神经病变包括已知的感染性或可能的感染性病因，是神经系统疾病中最大但最不为人所知的一类。这些疾病包括急性炎症性脱髓鞘性多神经根病（AIDP），这是一种高度致残的周围神经系统炎症性自身免疫性疾病，其特征是对称性轻瘫伴反射性松弛进展为神经肌肉麻痹。尽管具有压倒性的患病率和社会经济影响，但炎性周围神经病变（包括AIDP）患者的治疗仍然是姑息性的，并且在很大程度上依赖于使用非特异性免疫调节疗法。TNF-介导的自身反应性白细胞通过血神经屏障（BNB）进入周围神经的募集和运输是炎性周围神经病变（包括AIDP）的一个公认的早期病理标志。趋化因子MCP-1已被确定为这种炎症级联的关键启动因子，并且在受影响患者的血浆和腓肠神经中检测到MCP-1水平升高。我们实验室的机制研究最近表明，从BNB的周围神经微血管内皮细胞（pnmec）释放MCP-1需要活性单体gtp酶的存在，特别是Cdc42。假设：治疗性给药香叶基转移酶抑制剂- i将通过抑制TNF-介导的cdc42依赖性MCP-1从周围神经微血管内皮细胞释放来减轻实验性自身免疫性神经炎的发生和进展。这一假设将在体内使用实验性自身免疫性神经炎（EAN）进行验证，这是一种已建立的可临床翻译的AIDP大鼠模型，并在体外使用primary

DESCRIPTION (provided by applicant): Inflammatory peripheral neuropathies represent a considerable social and economic burden in the US and worldwide. Encompassing both known infectious or possibly infectious etiologies, inflammatory neuropathies constitute one of the largest and least understood spectrums of neurologic disorders. Inclusive among these disorders is acute inflammatory demyelinating polyradiculopathy (AIDP), a highly disabling inflammatory autoimmune disease of the peripheral nervous system that is characterized by symmetrical paresis with areflexia progressing to neuromuscular paralysis. Despite its overwhelming prevalence and socioeconomic impact, the treatment of patients with inflammatory peripheral neuropathies, including AIDP, remains palliative and largely relies on the use of non-specific immune-modulating therapies. TNF-¿ mediated recruitment and trafficking of autoreactive leukocytes across the blood-nerve barrier (BNB) and into peripheral nerves is a well-established early pathological hallmark of inflammatory peripheral neuropathies, including AIDP. The chemokine MCP-1 has been identified as a key initiator of this inflammatory cascade and elevated levels of MCP-1 have been detected in plasma and sural nerve of affected patients. Mechanistic studies from our lab have recently demonstrated that release of MCP-1 from peripheral nerve microvascular endoneurial endothelial cells (PNMECs) of the BNB requires the presence of active monomeric GTPases, in particular Cdc42. Hypothesis: Therapeutic administration of geranylgeranyltransferase inhibitor-I will attenuate the development and progression of experimental autoimmune neuritis by inhibiting TNF-¿ mediated Cdc42-dependent release of MCP-1 from peripheral nerve microvascular endoneurial endothelial cells. This hypothesis will be tested in vivo utilizing experimental autoimmune neuritis (EAN), an established clinically-translatable rat model of AIDP and in vitro using primary and transformed cultures of PNMECs. In Specific Aim 1, we will determine the therapeutic potential of prenyltransferase inhibitors on activation of the BNB by assessing (a) the clinical severity and course of EAN (b) EAN-induced changes in peripheral nerve function and (c) the content and distribution of immune infiltrates (macrophages and leukocytes) and MCP-1 in sciatic nerves of EAN rats, compared with vehicle-treated EAN control rats. In Specific Aim 2, we will identify, in vitro, the specific monomeric GTPases involved in the (a) intracellular distribution and (b) release of MCP-1 from TNF-¿ treated PNMECs using targeted siRNA knockdown of individual GTPases. The goal of this two-year exploratory proposal is to determine the therapeutic potential of prenyltransferase inhibitors as novel treatment options for patients with AIDP while continuing to elucidate the mechanisms by which monomeric GTPases promote TNF-¿ mediated inflammatory activation of the blood-nerve barrier.