CaMKII as a Mechanism & Intervention Target for Sickle Cell Pain

描述(由申请人提供)： 我们的长期目标是促进对镰状细胞病(SCD)疼痛的神经机制的了解，并开发有效的药物治疗方法。SCD中疼痛的神经生物学还知之甚少。目前已成功建立了多种转基因/基因敲除小鼠模型，并将其应用于SCD的研究。然而，最近才发表的疼痛发现表明，使用辐射热甩尾试验的NY1DD小鼠的疼痛敏感度增加。令人惊讶的是，这些小鼠的疼痛与年龄有关，发作时间约为6周。不幸的是，研究人员没有报告其他疼痛测量结果，也没有定义伯克利镰刀转基因小鼠的疼痛表型，这是一种更严重的SCD模型。在我们自己的初步研究中，我们在一系列用于研究动物其他疼痛类型的疼痛测试中检查了伯克利镰刀鼠和产仔的非镰刀鼠对照组。在这些初步研究中，我们发现存在触觉过敏和热痛觉过敏，脊髓CaMKII的表达和活性上调，与我们在其他炎症性和神经病理性疼痛模型中观察到的相似。在后一种模型中，我们已经确定 CaMKIIa是导致持续性疼痛的关键成分。我们观察到，脊神经结扎诱导的疼痛行为在CaMKIIa突变小鼠中没有出现。基于这些令人鼓舞的数据，我们建议通过使用标准的疼痛测试来广泛地表征Berkeley小鼠的疼痛行为，包括从出生后不久到成年或当反应平缓时，对自发疼痛行为和由热或机械刺激(冯·弗雷、Hargreaves、热板、甩尾、冷过敏)和炎症刺激(福尔马林、完全弗氏佐剂)诱发的疼痛行为进行的标准疼痛测试。其中一些疼痛测试用于我们正在进行的使用定量感觉测试(QST)对SC疼痛进行的人体研究。有意地，这些相似性将使我们能够解释SCD转基因小鼠模型的发现，同时考虑到其他疼痛小鼠模型和人类SCD疼痛模型的发现。我们将使用实时定量聚合酶链式反应、免疫印迹、免疫组织化学和酶动力学方法系统地检测CaMKIIa和总CaMKII在镰刀鼠和对照鼠中的表达和活性，并将这一潜在生物标志物的变化与疼痛的发生联系起来。为了直接验证脊髓CaMKIIa是促进和维持SCD慢性疼痛表现的分子机制这一假设，我们将使用化学、小干扰RNA(SiRNA)和基因敲除方法进行抑制CaMKIIa的药理学研究。我们建议在这些药理学研究中测试一种临床上使用的口服药物，我们已经发现该药物是CaMKII抑制剂，并在炎症性和神经病理性疼痛模型中减少疼痛行为。我们的次要策略是进行一项试验性翻译研究，通过定量感觉测试和计算机化的自我报告工具来表征人类的感觉性疼痛，以确定这种CaMKII抑制剂的安全性问题和临床潜力。这项建议的意义在于，它可能最终导致针对CaMKII途径的药物干预。(摘要结束)

DESCRIPTION (provided by applicant): Our long-term goal is to advance knowledge of the neural mechanisms of pain in sickle cell disease (SCD) and develop an effective pharmacologic treatment. The neurobiology of pain in SCD is poorly understood. Several transgenic/knock-out mouse models have been successfully produced and applied to study SCD. However, pain findings were only recently published that indicated increased pain sensitivity in NY1DD mice using a radiant heat tail-flick test. Strikingly, pain in these mice was age-dependent with an onset time around 6 weeks. Unfortunately, the investigators did not report other pain measurement findings or define a pain phenotype in Berkeley sickle transgenic mice, a model of a more severe form of SCD. In our own preliminary studies, we examined Berkeley sickle mice and littermate non-sickle controls in an array of pain tests that are used to study other pain types in animals. In these preliminary studies, we found the presence of tactile allodynia and thermal hyperalgesia and that spinal CaMKII expression and activity were upregulated, similar to what we observed in other mouse models of inflammatory and neuropathic pain. In the latter models, we have identified CaMKIIa to be a critical component leading to persistent pain. We observed that spinal nerve ligation-induced pain behaviors did not develop in CaMKIIa mutant mice. Based on these encouraging data, we propose to extensively characterize pain behaviors in Berkeley mice by employing standard pain tests for spontaneous pain behaviors and those evoked by thermal or mechanical stimuli (von Frey, Hargreaves, hot-plate, tail-flick, cold allodynia) and inflammatory stimuli (formalin, complete Freund's adjuvant) from shortly after birth through adulthood or when responses plateau. Some of these pain tests are used in our ongoing human studies of SC pain using quantitative sensory testing (QST). Intentionally, these similarities will allow us to interpret findings from the SCD transgenic mouse model with consideration of findings from other mouse models of pain and human SCD pain. We will use real time PCR, immunoblotting, immunohisto-chemistry, and enzymatic kinetics methods to systematically examine the expression and activity of CaMKIIa and total CaMKII in sickle and control mice and correlate the changes in this potential biomarker with the onset of pain. To directly test the hypothesis that spinal CaMKIIa is a molecular mechanism that promotes and maintains the manifestation of chronic pain in SCD, we will conduct pharmacological studies to inhibit CaMKIIa using chemical, small interfering RNA (siRNA), and gene knockout methods. We propose to test in these pharmacological studies a clinically used orally available drug that we have found to be a CaMKII inhibitor and to reduce pain behaviors in inflammatory and neuropathic pain models. Our secondary strategy is to conduct a pilot translational study to identify safety issues and clinical potential of this CaMKII inhibitor by characterizing sensory pain in humans with quantitative sensory testing and a computerized self-report tool. The significance of this proposal is that it may ultimately lead to pharmacological interventions that target the CaMKII-pathway. (End of Abstract)