Complement in Paclitaxel-induced peripheral neuropathy

项目摘要 接受紫杉醇治疗的患者中高达80%会发生紫杉醇诱导的周围神经病变(PIPN)。PIPN 以四肢远端神经性疼痛和表皮内神经纤维(IENF)丢失为特征。目前有 对于这种衰弱的神经病理性疼痛综合征没有有效的治疗方法。我们最近发现补体，一种 PIPN是先天免疫的重要组成部分，在PIPN的发展过程中扮演着一个未知但关键的角色。 补体激活导致1)过敏性毒素C3a和C5a的释放，通过它们的 受体C3aR和C5aR；2)形成膜攻击复合体(MAC)，介导细胞损伤。 由于大鼠在包括疼痛测量在内的许多行为测试中都优于小鼠，我们创造了第一个- 补体基因敲除(KO)大鼠缺乏补体C3，补体活化级联反应的中心成分。 我们的初步研究表明，紫杉醇在体外和体内都能引起补体激活。紫杉醇- 诱发的机械性痛觉异常(PIMA，疼痛的读数)，IENF的丢失，MAC的沉积，以及 背根神经节中的瞬时受体电位香草素4(TRPV4，一种关键的痛觉机械感受器) C3KO大鼠背根神经节(DRG)较WT对照组明显减少。另有报道称，巨噬细胞通过 CCL2/CCR2趋化信号进入DRG和DRG神经元细胞内钙内流起重要作用 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CCL2，随后将巨噬细胞招募到DRG；(Ii)上调TRPV4 通过激活C3aR/C5aR表达和刺激背根神经节钙离子内流；和/或(Iii)直接 通过MAC形成损伤DRG神经元。因此，抑制补体可以预防/治疗PIPN。 我们将首先确定补体在紫杉醇介导的CCL2/CCR2活化中的作用，巨噬细胞 以及C3aR/C5aR拮抗剂对PIPN中PIMA的治疗作用(目标1)。我们 然后将研究补体在紫杉醇介导的TRPV4上调，细胞内钙内流， 和背根节神经元的MAC形成(目标2)。最后，我们将把补体激活和IENF丢失联系起来。 1例发生PIPN(AIM 3)。这个项目将第一次阐明 补充性有助于PIPN的发展。我们的工作也可能为 补体靶向治疗PIPN的未来发展还没有有效的治疗方法。 因为其他周围神经疾病(例如，由于饮酒、艾滋病毒感染或糖尿病) 这项研究的结果也以远端神经病理性疼痛和IENF的丧失为特征，具有广泛的临床意义 在管理这些难以治疗的疼痛综合征方面的影响。

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.