Validation of Spinal Neurotensin Receptor 2 as an Analgesic Target

项目总结： 硬膜外/脊柱给药，如阿片类药物、齐康肽和局部麻醉药，在某些情况下有很好的疗效。 最难治的疼痛情况，如背部手术失败后的严重神经病理性疼痛、癌症疼痛和手术后 腹部/胸部大手术后的疼痛。尽管它们有很强的疗效，但它们的使用受到限制，主要是因为副作用 耐受性、肉芽肿、精神病和运动障碍等影响。新的脊髓止痛靶点的发现和验证 迫切需要发展治疗学。 在这里，我们建议在我们的机制研究的基础上，验证一个新的脊髓止痛靶点，神经降压素受体2(NTSR2) Contulakin-G(CGX)，已显示出对患有最难治疗的神经性疾病之一的人类的初步疗效 疼痛状况-脊髓损伤与疼痛相关。 CGX是一种蜗牛毒源多肽，与哺乳动物神经降压素具有同源性，已被证明对人类是安全的。一个 小规模的先导性1a期研究显示，在一些脊髓损伤相关疼痛的患者中有止痛效果。虽然， CGX没有良好的药代动力学特性，这些研究表明有可能成为一种新型的非阿片类止痛药 一种活跃在人类体内的机制。我们的初步研究表明CGX的镇痛作用是通过激活脊髓来实现的 神经降压素受体2(NTSR2)和随后电压门控性钙通道的抑制。NTSR2高表达于 啮齿动物中小型感觉神经元与电压门控性钙通道共表达。转录学 证实NTSR2在人背根神经节感觉神经元中有表达。重要的是，我们的初步研究表明，NTSR2 CGX的激活可产生深刻的止痛作用，且与快速耐受或 汽车封锁线。因此，初步数据支持脊髓NTSR2在痛觉调制中的作用，但该受体作为一种 止痛靶点尚未完成。 在这个项目中，我们建议对脊髓NTSR2作为止痛靶点进行强有力的验证，利用这两种药物中的三种 性别(大鼠、小鼠和人类)、两种模型(神经性疼痛和手术后疼痛)、药理学(SA1)和最新技术 基因工具，如CRISPR-CAS9编辑(SA2)和对疼痛的感觉和情感测量的评估。此外，我们 建议在多点临床试验后设计一项严格的两点平行确认研究(SA3)，以进一步验证脊柱 NTSR2作为止痛靶点。 如果成功，拟议中的研究可能导致具有高翻译潜力的非阿片类脊髓止痛药的开发。

Project Summary: Epidural/spinal administration of analgesics such as opioids, ziconotide and local anesthetics have profound efficacy in some of the most intractable pain conditions such as severe neuropathic pain after failed back surgery, cancer pain and post-operative pain after major abdominal/thoracic surgeries. Despite their profound efficacy, their use is limited primarily because of the side effects such as tolerance, granuloma, psychosis and motor block. Discovery and validation of new spinal analgesic targets for development of therapeutics is urgently needed. Here we propose to validate a novel spinal analgesic target, neurotensin receptor 2 (NTSR2), based upon our mechanistic studies of Contulakin-G (CGX), that has shown preliminary efficacy in humans suffering from one of the hardest to treat neuropathic pain condition-spinal cord injury associated pain. CGX is a snail venom derived peptide that has homology with mammalian neurotensin and was shown to be safe in humans. A small, pilot Phase1A study demonstrated analgesic effect in some patients with spinal cord injury-associated pain. Although, CGX does not have favorable pharmacokinetic properties, these studies suggested a possibility of a novel, non-opioid, analgesic mechanism that is active in humans. Our preliminary studies suggest CGX produces its analgesic actions via activation of spinal neurotensin receptor 2 (NTSR2) and subsequent inhibition of voltage-gated calcium channels. NTSR2 is highly expressed in small/medium size sensory neurons in rodents and co-expressed with voltage gated calcium channels. Transcriptomics confirmed NTSR2 expression in human dorsal root ganglia sensory neurons. Importantly, our pilot studies show that NTSR2 activation by CGX produces profound analgesia and is not associated with unwarranted side effects such as rapid tolerance or motor blockade. Preliminary data thus support a role of spinal NTSR2 in pain modulation, but validation of this receptor as an analgesic target has not been done. In this project, we propose to perform a robust validation of spinal NTSR2 as an analgesic target utilizing three species of both sexes (rat, mice and human), two models (neuropathic pain and post-surgical pain), pharmacological (SA1) and state of the art genetic tools such as CRISPR-Cas9 editing (SA2) and assessment of both sensory and affective measures of pain. Moreover, we propose a rigorous, two-site parallel confirmation study (SA3) designed after multisite clinical trials to further authenticate spinal NTSR2 as an analgesic target. If successful, proposed studies could lead to a development of non-opioid spinal analgesic that has high translational potential.