Mechanistic Role of Monomeric GTPases in Experimental Autoimmune Neuritis

描述(由申请人提供)：炎症性周围神经病在美国和世界范围内代表着相当大的社会和经济负担。炎症性神经病包括已知的感染性或可能的感染性病因，是神经系统疾病中规模最大、最不为人所知的疾病之一。这些疾病包括急性炎症性脱髓鞘多神经根病(AIDP)，这是一种高度致残性的周围神经系统炎症性自身免疫性疾病，其特征是对称性瘫痪，反射障碍进展为神经肌肉瘫痪。尽管炎症性周围神经病的发病率和社会经济影响是压倒性的，但包括AIDP在内的炎症性周围神经病的治疗仍然是姑息性的，在很大程度上依赖于非特异性免疫调节疗法的使用。肿瘤坏死因子-β介导的自身反应性白细胞的募集和运输穿过血神经屏障(BNB)进入周围神经是包括AIDP在内的炎症性周围神经病的一个公认的早期病理特征。趋化因子MCP-1已被确定为这一炎性级联反应的关键启动者，在受影响患者的血浆和腓肠神经中检测到MCP-1水平升高。我们实验室最近的机制研究表明，BNB的周围神经微血管内皮细胞(PNMECs)释放MCP-1需要活性单体GTP酶的存在，特别是CDC42。假设：香叶基香叶素转移酶抑制剂-I的治疗应用将通过抑制肿瘤坏死因子-β介导的CDC42依赖的外周神经微血管内皮细胞释放MCP-1来延缓实验性自身免疫性神经炎的发生和进展。这一假说将在体内利用实验性自身免疫性神经炎(EAN)进行验证，EAN是一种已建立的AIDP临床可翻译大鼠模型，并在体外使用初级 和转化的PNMEC的培养。在具体目标1中，我们将通过评估(A)EAN的临床严重程度和病程，(B)EAN引起的周围神经功能的变化，以及(C)免疫浸润物(巨噬细胞和白细胞)和单核细胞趋化蛋白-1(MCP-1)在EAN大鼠坐骨神经中的含量和分布，与赋形剂治疗的EAN对照组大鼠进行比较，以确定前烯基转移酶抑制剂对BNB激活的治疗潜力。在特定的目标2中，我们将通过靶向敲除单个GTP酶的靶向siRNA，在体外鉴定与(A)细胞内分布和(B)从肿瘤坏死因子处理的PNMECs释放MCP-1有关的特异性单体GTP酶。这项为期两年的探索性计划的目标是确定戊烯基转移酶抑制剂作为AIDP患者新的治疗选择的治疗潜力，同时继续阐明单体GTP酶促进肿瘤坏死因子-β介导的血-神经屏障炎症激活的机制。

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.