The Effect of a Nerve Growth Factor Mimetic in Demyelination and Remyelination

描述(申请人提供)：多发性硬化症(MS)是一种慢性、不可预测的中枢神经系统(CNS)疾病，可能由多种因素引起，如遗传易感性、性别、环境因素和接触看似无害的病毒。针对中枢神经系统脱髓鞘疾病(如MS)的药物治疗一直很少，主要是通过广谱免疫抑制发挥作用，其作用机制尚不完全清楚。最近的研究使模拟功能性蛋白质配体-受体相互作用的小分子模拟(SMM)在潜在的治疗开发中脱颖而出。我们实验室将使用神经生长因子(NGF)的SMM，即C31或LM11A-31，作为改变中枢神经系统脱髓鞘和/或重新髓鞘形成的治疗剂。众所周知，NGF通过酪氨酸受体激酶A(TrkA)在中枢神经系统中对神经元和神经胶质细胞的存活和分化起营养作用。然而，与其他神经营养因子不同的是，NGF还具有通过p75神经营养因子受体(P75NTR)诱导其前体形式proNGF凋亡的能力。C31由NGF的2-环1结构域残基组成，与p75NTR相互作用。先前的研究表明，NGF Loop 1模拟物通过p75NTR依赖的信号通路在体外提供了对神经细胞死亡的保护，并在proNGF存在的情况下保护成熟的少突胶质细胞(OL)免受细胞死亡的影响，这可能是通过启动促生存信号来实现的。为了进一步研究C31在体内的作用，我们实验室将使用铜比林中毒模型，在该模型中，细胞数量和髓鞘形成的变化在C57BL/6小鼠的胼胝体中是可重现和可预测的。虽然p75NTR主要在神经元发育的早期表达，但我们有初步的数据表明，p75NTR在脱髓鞘的胼胝体中可以检测到重新表达。使用我们的脱髓鞘和再髓鞘铜中毒模型，我们假设C31在体内保护OL。我们预测，这可能会阻止或延迟脱髓鞘，或增加再髓鞘形成的速度。这项建议的具体目的是为了证明C31在脱髓鞘/再髓鞘形成过程中对细胞、分子和形态的影响，并最终将p75NTR的表达与C31的作用机制联系起来。如果C31的应用阻碍了疾病的进展，那么这可能为SMM的可行性和机制提供洞察力，具有潜在的脱髓鞘疾病的治疗分支。这项建议探索了一种潜在的新型治疗化合物C31的可行性，该化合物模仿神经生长因子的一段，以改善中枢神经系统脱髓鞘。C31已被证明在体外对少突胶质细胞具有保护作用，因此有必要在体内检测其功能。如果这项建议提供了C31改善中枢神经系统病理的证据，那么C31就有可能转向临床考虑，最终应用于人类疾病，如多发性硬化症。

DESCRIPTION (provided by applicant): Multiple sclerosis (MS) is a chronic, unpredictable neurological disease of the central nervous system (CNS) and may be caused by more than one factor, such as genetic predisposition, gender, environmental factors, and exposure to seemingly innocuous viruses. Pharmacologic therapies targeting CNS demyelinating diseases such as MS have been sparse and mostly act by broad-spectrum immune suppression of which the mechanisms of actions are not completely understood. Recent studies have brought small molecule mimetics (SMMs) that emulate functional protein ligand-receptor interactions to the fore in potential therapeutic development. Our laboratory will use an SMM of nerve growth factor (NGF), namely C31 or LM11A-31, as a therapeutic agent to alter CNS demyelination and/or remyelination. NGF is well known for its trophic role in neuronal and glial cell survival and differentiation in the CNS via tyrosine receptor kinase A (TrkA). However, NGF, unlike other neurotrophins, also has the ability to induce apoptosis in its precursor form, proNGF, through the p75 neurotrophin receptor (p75NTR). C31, which is comprised of residues of the 2-loop 1 domain of NGF, interacts with p75NTR. Previous studies show NGF Loop 1 mimetics provide in vitro protection against neuronal cell death via p75NTR-dependent signaling and also afforded protection of mature oligodendrocytes (OLs) from cell death in the presence of proNGF, presumably by initiating pro-survival signaling. To further study the effect of C31 in vivo, our laboratory will use the cuprizone intoxication model in which changes in cellular populations and myelination are both reproducible and predictable in the corpus callosum of a C57BL/6 mouse. Although p75NTR is mainly expressed during early neuronal development, we have preliminary data that re-expression of p75NTR can be detected by immunohistochemistry in the demyelinating corpus callosum. Using our cuprizone intoxication model of demyelination and remyelination, we hypothesize that C31 protects OLs in vivo. We predict this may prevent or delay demyelination or increase the rate of remyelination. The specific aims of this proposal are designed to demonstrate the effects of C31 on the cellular, molecular, and morphologic profiles during demyelination/remyelination, and to eventually link the expression profile of p75NTR to the mechanism of C31 action. If administration of C31 hinders disease progression, then this may provide insights to feasibility and mechanism of SMM with potential therapeutic ramifications for demyelinating diseases. This proposal explores the feasibility of a potential novel therapeutic compound, C31 that mimics a fragment of nerve growth factor, to ameliorate central nervous system demyelination. C31 has been shown to protect oligodendrocytes in vitro and examination of its function in vivo is warranted. If this proposal provides evidence that C31 ameliorates CNS pathology, then there is a potential to move C31 towards clinical considerations for the eventual application to human diseases such as multiple sclerosis.