From therapeutic mechanisms to unraveling the pathophysiology of MS

多发性硬化（MS）是中枢神经系统（CNS）的炎性脱髓鞘疾病。MS的病因尚不清楚，但该疾病在暴露于环境触发因素的遗传易感个体中发展。在MS中长期支持的假设涉及在进入CNS的外周中产生的自身反应性T和B细胞，在那里它们诱导先前正常的神经组织的损伤。然而，与动物模型实验性自身免疫性脑脊髓炎（EAE）相反，在MS中既没有明确定义免疫应答的靶标也没有明确定义负责CNS损伤的细胞。此外，靶向EAE中CNS组织破坏发展的潜在过程的一些MS疾病修饰治疗（DMT）的失败（例如IFN-g、TNF-a抑制剂）表明不同的机制可能导致MS与EAE中残疾的发展。因此，有必要确定特定于MS的病理生理机制，但可能无法从EAE模型预测。 治疗试验代表了一个机会，以调查如何特定的扰动的生物系统影响MS疾病的过程。该项目的目标是仔细研究MS I/II期临床试验中应用新型治疗药物引起的生物学扰动，以确定CNS组织损伤的机制，以及那些有益的免疫调节和免疫介导的神经保护的基础。通过将生物系统中测量的变化与CNS破坏的结构变化（通过神经成像测量）以及新的、更敏感的临床和功能结果相关联，我们可以了解哪些生物过程在MS发病机制中是有益的，哪些是有害的。此外，了解所应用的疗法的哪些效应是其治疗益处的基础将使我们能够定义指示性的生物标志物，并且理想地还预测完全治疗反应。最后，我们还认为，类似于心血管、感染性疾病或肿瘤学，完全演变的CNS疾病的成功治疗将需要合理的、患者特异性的联合治疗，这些治疗针对负责他/她的疾病表达的所有致病机制。 该项目是对神经免疫疾病患者的综合多模式分析项目的延伸，因为它在干预性的、由免疫系统启动的临床试验中测试了来自该项目的假设。 2017年，我们启动了适应性平台II期临床试验，称为TRAP-MS：通过精确靶向残留活性，生物标志物指导的多发性硬化症联合治疗（方案17-N-0083; clinicaltrials.gov标识符NCT 03109288）。TRAP-MS试验测试了我们在过去6年中根据项目获得的知识得出的假设：对神经免疫性疾病患者进行综合多模式分析，分析患者接受当前FDA批准的DMT治疗时的残留MS活性，以及与MS疾病进展和疾病严重程度相关的致病过程。 1. 大部分接受FDA批准的DMT治疗的MS患者保留了可测量的炎症，这些炎症被划分为CNS组织，由终末分化（因此主要是非增殖）的免疫细胞组成。这种炎症导致CNS组织破坏，并可能受到羟氯喹的限制，羟氯喹限制了抗原加工/呈递和穿孔素/颗粒酶介导的细胞毒性。 2. 慢性鞘内炎症导致先天免疫细胞的激活和重编程，特别是髓系细胞，这有助于CNS组织破坏和残疾的积累。这种髓系（小胶质细胞、巨噬细胞和髓系树突状细胞）的不适当激活可被吡格列酮抑制。我们已经在体外证明，吡格列酮还可以纠正单核细胞/巨噬细胞吞噬髓鞘的功能缺陷，这可能会抑制天然髓鞘再生。最后，通过诱导新线粒体的形成和增加CNS细胞中的线粒体体积，也可能具有神经保护作用，特别是对具有高能量需求的脱髓鞘轴突。 3. 另一个与MS严重性相关的过程（即，神经功能障碍的累积速度）是毒性星形胶质细胞增生。我们对小分子进行了高通量筛选（大多数FDA批准用于各种适应症），以鉴定炎症诱导的星形胶质细胞从正常转化为神经毒性表型的抑制剂。该筛选将丹曲林（和其他与内质网应激相关的药物）鉴定为毒性星形胶质细胞标记的抑制剂。因此，TRAP-MS方案检验了丹曲林将抑制与毒性星形胶质细胞相关的CSF生物标志物并且这将导致残疾累积减缓的假设。 4. 上述过程在个体患者中差异表达，并且可以通过脑脊液（CSF）生物标志物来测量。因此，CSF生物标志物可指导最佳治疗的选择，并反映其对残留MS活性的疗效。 5. 为了达到高水平的疗效（理想情况下完全抑制MS进展），患者将需要靶向患者CNS中活跃的所有致病机制的联合治疗。 我们期望伴随TRAP-MS试验的生物标志物和机制研究将提供在广泛的MS实践中应用精确神经学所需的缺失知识。我们预计，并非所有选择用于TRAP-MS试验初始测试的药物都将证明其在鞘内隔室中的预期疗效，该方案包括个别药物的停药标准及其未来与其他候选药物的补充。

Multiple Sclerosis (MS) is an inflammatory, demyelinating disorder of the central nervous system (CNS). The etiology of MS remains unclear, but the disease develops in genetically susceptible individuals exposed to environmental triggers. The long-favored hypothesis in MS implicates autoreactive T and B cells generated in the periphery that access the CNS, where they induce injury of previously normal neural tissues. However, in contrast to the animal model experimental autoimmune encephalomyelitis (EAE), neither the target(s) of the immune response nor the cells responsible for CNS damage have been unequivocally defined in MS. Furthermore, the failure of some MS disease modifying treatments (DMTs) that target processes underlying the development of CNS tissue destruction in EAE (e.g. IFN-g, TNF-a inhibitors) indicates that different mechanisms may cause the development of disability in MS versus EAE. Therefore, there is a need to identify pathophysiological mechanisms that are specific for MS, but may not be predicted from EAE models. Therapeutic trials represent an opportunity to investigate how specific perturbations of the biological system affect MS disease process. The goal of this project is to carefully study the biological perturbations induced by the application of novel therapeutic agents in Phase I/II clinical trials in MS, to define mechanisms of CNS tissue injury, but also those that underlie beneficial immunoregulation and immune-mediated neuroprotection. By correlating changes measured in the biological system with structural changes of CNS destruction (measured by neuroimaging), and with novel, more sensitive clinical and functional outcomes, we can understand which biological processes are beneficial and which are harmful in the MS pathogenesis. Additionally, understanding which effects of applied therapies underlie their therapeutic benefit will allow us to define biomarkers that are indicative, and ideally also predictive of the full therapeutic response. Finally, we also believe that analogously to cardiovascular, infectious diseases or oncology, successful treatment of fully evolved CNS disorder will require rational, patient-specific combination treatments that target all pathogenic mechanism responsible for his/her disease expression. This project is an extension of the: Comprehensive multimodal analysis of patients with neuroimmunological diseases project, in that it tests hypotheses derived from this project in interventional, investigator-initiated clinical trials. In 2017 we opened adaptive, platform Phase II clinical trial called TRAP-MS: Targeting Residual Activity by Precision, biomarker-guided combination therapies of Multiple Sclerosis (protocol 17-N-0083; clinicaltrials.gov identifier NCT03109288). TRAP-MS trial tests hypotheses derived from the knowledge we acquired in the past 6 years under project: Comprehensive multimodal analysis of patients with neuroimmunological diseases about residual MS activity when patients are treated with current FDA-approved DMTs and about pathogenic processes associated with disease progression and disease severity in MS. Specifically TRAP-MS trial tests following hypotheses: 1. Large proportion of MS patients treated with FDA-approved DMTs retain measurable inflammation that is compartmentalized to the CNS tissue and consists of terminally-differentiated (and therefore largely non-proliferating) immune cells. This inflammation contributes to CNS tissue destruction and may be limited by hydroxychloroquine, which limits antigen-processing/presentation and perforin/granzymes-mediated cytotoxicity. 2. Chronic intrathecal inflammation leads to activation and reprogramming of innate immunity cells, especially myeloid lineage, which contributes to CNS tissue destruction and accumulation of disability. This inappropriate activation of myeloid lineage (microglia, macrophages and myeloid dendritic cells) may be inhibited by pioglitazone. We have shown in-vitro that pioglitazone also corrects functional defect in myelin phagocytosis by monocytes/macrophages, which may inhibit natural remyelination. Finally, through inducing formation of new mitochondria and increasing mitochondrial bulk in CNS cells may also have neuro-protective effects, especially on demyelinated axons, which have high energy demands. 3. Another process that correlates with MS severity (i.e., the speed of accumulation of neurological disability) is toxic astrogliosis. We performed high throughput screen of small molecules (most FDA-approved for varied indications) to identify inhibitors of the inflammation-induced transformation of astrocytes from normal, to neurotoxic phenotype. This screen identified dantrolene (and other drugs related to endoplasmic reticulum stress) as inhibitors of toxic astrocyte signature. Thus, TRAP-MS protocol tests the hypothesis that dantrolene will inhibit CSF biomarkers associated with toxic astrocytes and that this will lead to slowing of the disability accumulation. 4. Afore-mentioned processes are differentially expressed in individual patients and can be measured by cerebrospinal fluid (CSF) biomarkers. Therefore, CSF biomarkers may guide selection of optimal therapy and reflect its efficacy on residual MS activity. 5. To achieve high level of efficacy (ideally complete inhibition of MS progression) patients will need combination treatments that target all pathogenic mechanisms that are active in patients CNS. We expect that biomarker and mechanistic studies that accompany TRAP-MS trial will provide missing knowledge necessary for application of precision neurology in broad MS practice. We expect that not all drugs selected for initial testing in TRAP-MS trial will prove their desired efficacy in the intrathecal compartment and this protocol includes stopping criteria for individual drugs and their future replenishment with other candidate agents.