Complement in Paclitaxel-induced peripheral neuropathy

项目摘要 紫杉醇诱导的周围神经病变（PIPN）发生在接受这种治疗的患者中高达80%。PIPN 其特征在于远端肢体神经性疼痛和表皮内神经纤维（IENF）的损失。目前还 没有有效的治疗方法来治疗这种使人衰弱的神经性疼痛综合征。我们最近发现， 先天免疫的关键成分，在PIPN的发展中起着以前未知但关键的作用。 补体激活导致1）过敏毒素C3 a和C5 a的释放，以通过它们的释放介导炎症。 受体C3 aR和C5 aR，和2）形成膜攻击复合物（MAC）以介导细胞损伤。 因为大鼠在许多行为测试中上级小鼠，包括疼痛测量，我们创造了第一个- 缺乏补体激活级联反应的中心成分C3的任何补体敲除（KO）大鼠。 我们的初步研究表明，紫杉醇在体外和体内引起补体激活。太平洋- 诱导的机械性异常性疼痛（PIMA，疼痛的读出），IENF的丧失，MAC的沉积和 背根神经节的瞬时受体电位香草酸4（TRPV 4） (DRG)在C3 KO大鼠中比在WT对照中少得多。其他人报道，巨噬细胞浸润， CCL 2/CCR 2化学引诱物信号进入DRG和DRG神经元内的细胞内钙内流起重要作用 在PIPN中的角色基于这些发现，我们假设补体激活（i）刺激DRG 神经元产生CCL 2，随后将巨噬细胞募集到DRG中;（ii）上调TRPV 4 表达并通过C3 aR/C5 aR活化刺激DRG中的Ca 2+内流;和/或（iii）直接 通过MAC形成损害DRG神经元。因此，抑制补体应该预防/治疗PIPN。 我们将首先确定补体在紫杉醇介导的CCL 2/CCR 2活化中的作用，巨噬细胞 PIPN中C3 aR/C5 aR拮抗剂对PIMA的治疗作用（目的1）。我们 然后将研究补体在紫杉醇介导的TRPV 4上调，细胞内Ca 2+内流， 和背根节神经元中MAC的形成（目的2）。最后，我们将把补体激活和IENF丢失联系起来， PIPN患者（目标3）。该项目将首次阐明 补充有助于PIPN的发展。我们的工作也可能为 未来开发补体靶向疗法来管理尚未有效治疗的PIPN。 因为其他周围神经病变（例如，由于饮酒、艾滋病毒感染或糖尿病）， 也以远端神经性疼痛和IENF丧失为特征，本研究的结果将具有广泛的临床意义。 在管理这些难以治疗的疼痛综合征的影响。

Project Summary Paclitaxel-induced peripheral neuropathy (PIPN) occurs in up to 80% of patients received this therapy. PIPN is characterized by distal limb neuropathic pain and loss of intraepidermal nerve fibers (IENF). Currently there is no effective treatment for this debilitating neuropathic pain syndrome. We recently found that complement, a key component of innate immunity, plays a previously unknown yet pivotal role in the development of PIPN. Complement activation leads to 1) release of anaphylatoxins C3a and C5a to mediate inflammation through their receptors C3aR and C5aR, and 2) formation of membrane attack complex (MAC) to mediate cell damage. Because rats are superior to mice for many behavioral tests, including pain measurement, we created the first- ever complement knockout (KO) rats lacking C3, the central component of the complement activation cascade. Our preliminary studies showed that Paclitaxel causes complement activation in vitro and in vivo. Paclitaxel- induced mechanical allodynia (PIMA, a readout of pain), loss of IENF, deposition of MAC, and expression of transient receptor potential vanilloid 4 (TRPV4, a key mechanosensory receptor for pain) in dorsal root ganglion (DRG) are much less in C3 KO rats than in WT controls. Others have reported that macrophage infiltration by CCL2/CCR2 chemoattractant signals into DRG and intracellular calcium influx in DRG neurons play essential roles in PIPN. Based on these findings, we hypothesize that complement activation (i) stimulates DRG neurons to produce CCL2 to subsequently recruit macrophages into DRG; (ii) upregulates TRPV4 expression and stimulates Ca2+ influx in DRG through C3aR/C5aR activation; and/or (iii) directly damages DRG neurons through MAC formation. Thus, inhibiting complement should prevent/treat PIPN. We will first determine the role of complement in paclitaxel-mediated CCL2/CCR2 activation, macrophage infiltration into DRG, as well as the therapeutic effect of C3aR/C5aR antagonists on PIMA in PIPN (Aim 1). We will then examine the role of complement in paclitaxel-mediated TRPV4 upregulation, intracellular Ca2+ influx, and MAC formation in DRG neurons (Aim 2). Finally, we will correlate complement activation and loss of IENF in patients developed PIPN (Aim 3). This project will, for the first time, elucidate the mechanisms by which complement contributes to the development of PIPN. Our work might also provide a solid foundation for the future development of complement-targeted therapeutics to manage PIPN that has no effective treatment yet. Because other peripheral neuropathies (e.g., due to alcohol consumption, HIV infection or Diabetes Mellitus) are also characterized by distal neuropathic pain and loss of IENF, findings of this study would have broad clinical impact in managing these hard-to-treat pain syndromes.