Therapeutic benefit of targeting neuroinflammation in spinal cord injury with a novel small molecule inhibitor of the RNA regulator HuR

脊髓损伤(SCI)是毁灭性的，最常影响年轻的退伍军人。有重要的长期意义 发病率高，寿命短，经济负担重。因为它的再生能力很差 对于脊髓，制定早期干预措施，将继发性组织损伤降至最低是当务之急。一位少校 炎症级联反应是继发性组织损伤和神经病理性疼痛的始动因素 由激活的胶质细胞(小胶质细胞和星形胶质细胞)触发。这一级联反应在脊髓损伤后立即开始。 释放细胞因子、活性物质和血管活性物质。这种分泌物对人体造成损害 神经元、少突胶质细胞和其他处于或超过损伤水平的细胞通过直接细胞毒作用 机制或间接通过促进细胞毒性和血管源性水肿、血管妥协和 组织缺血。这些炎症介质也会触发导致慢性疼痛的通路。这个 炎症级联因神经胶质细胞产生的趋化因子而进一步加速，这些趋化因子可招募外周免疫 细胞，包括中性粒细胞和单核细胞，在损伤的急性期。最初的神经胶质的主要驱动力 Hur是一种RNA调节因子，通过以下途径促进关键炎症介质的表达 转录后机制。炎性介质如IL-1β、IL-6、肿瘤坏死因子-α和诱导型一氧化氮合酶 HUR结合的3‘非翻译区(ARE)富含腺嘌呤和尿苷的元件 调节它们的表达。我们先前在脊髓损伤中的工作表明，HUR在SCI急性期被激活，并且 当在胶质细胞中过度表达时，会加重损伤。我们的团队已经开发出一种新型的小分子Hur 阻断神经胶质细胞中炎性介质诱导的抑制剂。在一项关于SCI的试点研究中，使用了MID- 胸部挫伤模型，我们观察了临床缺陷和神经元丢失的减轻 缓蚀剂，SRI-42127。我们还发现，在周围神经损伤模型中，SRI-42127可以减少痛觉过敏性疼痛。 在这项提议中，我们假设HUR驱动促炎和毒性分泌体的表达 通过在脊髓损伤早期触发的驻留神经胶质细胞，抑制HUR将减少 继发性组织损伤，改善运动结果，减少神经病理性疼痛。我们提出3个具体的建议 目的：(1)进一步表征SRI-42127抑制HUR对脊髓损伤恢复的有利作用；(2)评估 抑制HUR促进脊髓损伤后恢复的机制；(3)评估神经胶质HUR的作用 脊髓损伤后的炎症反应和组织损伤。这项建议的长期目标是推进 我们的小分子HUR抑制剂作为急性脊髓损伤的治疗药物，并从机制上了解 ARE介导的转录后调控影响SCI(继发性组织损伤、运动恢复和 神经病理性疼痛)。这一方案的创新之处在于研究了一类新型的HUR抑制剂 脊髓损伤后急性炎症反应的靶向治疗及其机制研究 脊髓损伤中的转录途径(到目前为止基本上还未被探索)。这个应用程序的意义在于它 关注一种最终可能在战场上使用的治疗方法，因为我们的 临床前研究表明，SRI-42127出色且快速地渗透到中枢神经系统 外周给药，以及减轻神经元丢失和神经病理性疼痛的效果。《象征》 扩展到脊髓损伤以外，因为相同的HUR调节通路在其他急性中枢神经系统中驱动神经炎症 损伤(如创伤性脑损伤或中风)和慢性神经疾病(如肌萎缩侧索硬化症和阿尔茨海默病)。

Spinal cord injury (SCI) is devastating and most often affects younger Veterans. There is significant long-term morbidity, a shortened life span, and a high financial burden. Because of the poor regenerative capacity of the spinal cord, development of early interventions that minimize secondary tissue injury is a priority. A major contribution to secondary tissue damage and the initiation of neuropathic pain is the inflammatory cascade triggered by activated glial cells (microglia and astroglia). This cascade begins immediately after SCI with glial release of cytokines, reactive species, and vasoactive substances. This secretome produces damage to neurons, oligodendrocytes and other cells at and beyond the level of injury through direct cytotoxic mechanisms or indirectly through the promotion of cytotoxic and vasogenic edema, vascular compromise, and tissue ischemia. These inflammatory mediators also trigger pathways that lead to chronic pain. The inflammatory cascade is further accelerated by glial production of chemokines which recruit peripheral immune cells, including neutrophils and monocytes, within the acute phase of injury. A major driver of the initial glial response is HuR, an RNA regulator that promotes expression of key inflammatory mediators through posttranscriptional mechanisms. Inflammatory mediators such as IL-1β, IL-6, TNF-α and iNOS contain adenine- and uridine-rich elements in the 3’ untranslated region (ARE) to which HuR binds and positively regulates their expression. Our prior work in SCI shows that HuR is activated in the acute phase of SCI and exacerbates injury when overexpressed in glia. Our team has developed a novel class of small molecule HuR inhibitors that blocks induction of inflammatory mediators in glial cells. In a pilot study of SCI using a mid- thoracic contusion model, we observed attenuation of clinical deficits and neuronal loss with the prototype HuR inhibitor, SRI-42127. We also found that SRI-42127 reduced allodynic pain in a peripheral nerve injury model. In this proposal we hypothesize that HuR drives expression of a pro-inflammatory and toxic secretome by resident glia that is triggered in the early stages of SCI, and that inhibiting HuR will reduce secondary tissue injury, improve motor outcome and reduce neuropathic pain. We propose 3 specific aims: (1) Further characterize the beneficial effect of HuR inhibition by SRI-42127on SCI recovery, (2) Assess mechanisms by which HuR inhibition improves recovery after SCI, and (3) Assess the contribution of glial HuR to inflammatory responses and tissue injury in SCI. The long term objectives of this proposal are to advance our small molecule HuR inhibitors as a therapy in acute SCI and to gain a mechanistic understanding of how ARE-mediated post-transcriptional regulation impacts SCI (secondary tissue injury, motor recovery and neuropathic pain). The innovation of this proposal is the investigation of a novel class of HuR inhibitors for therapeutically targeting the acute inflammatory response in SCI and the mechanistic investigation of post- transcriptional pathways (to date essentially unexplored) in SCI. The significance of this application is its focus on a treatment approach that might eventually be used in the battlefield at the time of acute injury as our preclinical studies indicate excellent and fast penetration of SRI-42127 into the central nervous system with peripheral administration, and a mitigating effect on neuronal loss and neuropathic pain. The signfiicance extends beyond SCI as the same HuR-regulated pathways drive neuroinflammation in other acute CNS injuries (e.g. traumatic brain injury or stroke) and chronic neurological diseases (e.g. ALS and Alzheimers).