From therapeutic mechanisms to unraveling the pathophysiology of MS

从治疗机制到揭示多发性硬化症的病理生理学

• 批准号: 8557073
• 负责人: Bibiana Bielekova
• 金额: $ 136.29万
• 依托单位: NATIONAL INSTITUTE OF NEUROLOGICAL DISORDERS AND STROKE
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/8557073
• 关键词: Adverse effects; Affect; Affinity; Animal Model; Antigen Presentation; Antigens; Autoimmunity; Autologous; B-Lymphocytes; Biological; Biological Markers; Biological Process; Biology; Blood - brain barrier anatomy; Brain; Cell physiology; Cells; Clinical; Clinical Trials; Complex; Coupled; Daclizumab; Data; Dendritic Cells; Development; Disease; Double-Blind Method; Enrollment; Enzymes; Etiology; Experimental Autoimmune Encephalomyelitis; Failure; Functional disorder; Generations; Goals; Helper-Inducer T-Lymphocyte; Human; IL2RA gene; IL2RB gene; Immune; Immune response; Immune system; Individual; Inflammatory; Injury; Interferon Type II; Interleukin-2; Investigational New Drug Application; Lymphoid Cell; Lymphoid Follicle; Lymphoid Tissue; Measures; Mediating; Metabolism; Mitochondria; Modality; Multiple Sclerosis; Myelogenous; NQO1 gene; Natural Killer Cells; Nervous System Trauma; Neuraxis; Neurologic; Outcome; Oxidative Stress; Pathogenesis; Patients; Peripheral Blood Mononuclear Cell; Phase; Phase II Clinical Trials; Placebo Control; Population; Primary Progressive Multiple Sclerosis; Process; Property; Protocols documentation; Regulation; Research Personnel; Secondary Progressive Multiple Sclerosis; Signal Transduction; Stimulus; Synapses; T-Cell Activation; T-Cell Receptor; T-Lymphocyte; TNF gene; Testing; Therapeutic; Therapeutic Agents; Therapeutic Effect; Therapy Clinical Trials; Time; Tissues; Translating; Treatment outcome; Ubiquinone; Work; analog; autoreactive T cell; biological systems; central nervous system demyelinating disorder; disability; granzyme K; idebenone; immunoregulation; improved; inhibitor/antagonist; killings; lipophilicity; mitochondrial dysfunction; neuroimaging; neuroprotection; novel; novel therapeutics; receptor; relating to nervous system; repaired; response; rituximab; therapeutic target; therapy resistant

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 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 identified in MS. Furthermore, the failure of some MS treatments targeting processes that underlie 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. Therapeutic trials, especially those that investigate novel therapeutic agents, represent a unique 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 in order 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 (e.g. different functions of the T cells or other immune cell subsets) with structural changes of CNS destruction or repair (measured by neuroimaging modalities), and with clinical 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. We are currently studying immunomodulatory properties of three therapeutic agents: daclizumab, idebenone and rituximab in 3 investigator-initiated Phase I/II clinical trials performed under Investigational New Drug (IND) application (PI, Bibiana Bielekova). Our results are briefly summarized below: Daclizumab is a humanized monoclonal Ab against CD25, which is the alpha chain of the IL-2 receptor (IL-2R). CD25 is highly upregulated on activated T cells and contribution of CD25 to high-affinity IL-2 signaling was believed to be paramount for expansion of effector T cells. Thus, it was expected that daclizumab therapy will result in inhibition of T cell functions. While we have demonstrated that daclizumab is highly effective in suppressing MS-related inflammatory activity, this effect was not paralleled by inhibition of T cells. Instead, daclizumab selectively expands CD56bright natural killer (NK) cells and that this human-specific NK cell population has immunoregulatory function through its ability to kill activated autologous T cells. CD56bright NK cells utilize new mechanism (Granzyme-K; GzK) for killing T cells and GzK expression is selectively upregulated by daclizumab treatment. The expansion of CD56bright NK cells correlated with treatment outcome, suggestive that it can be utilized as biomarker of therapeutic response. This observation has now been fully reproduced in two double-blind, placebo-controlled multicenter Phase II/IIb trials of daclizumab in MS. We continue to study the mechanism of action (MOA) of daclizumab in MS in therapeutic trial of DAC-HYP (second generation of daclizumab) in patients with MS (protocol 10-N-0125), with the goal to determine all effects of daclizumab on human immune system. Through this work we described two novel MOA, which also revealed novel aspects of IL-2 biology: 1. daclizumab blocks activation of T cells by inhibiting CD25 expression on activated (i.e. mature) myeloid dendritic cells (mDCs). mDCs express CD25 and can produce IL-2, but cannot consume it because they lack another important singling chain, CD122. Instead, mDCs use their CD25 to transpresent IL-2, which they secrete into immune synapse, to a T cell that is being activated in antigen-specific manner. This IL-2 signal, given in conjunction with T cell receptor and costimulatory stimuli then allows T cell to enter proliferation cycle and clonally expand. 2. Finally, we recently described that daclizumab therapy also alters development of innate lymphoid cells (ILCs), by skewing differentiation of their common precursor away from pro-inflammatory lymphoid tissue inducer (LTi) cells and toward immunoregulatory CD56bright NK cells. This effect is paradoxical, by promoting IL-2 signaling via intermediate affinity IL-2R. Furthermore, we demonstrated that this effect of daclizumab normalizes enhanced levels of circulating LTi cells in MS patients to levels comparable to those observed in healthy subjects. Thus our data for the first time implicate LTi cells in human autoimmunity and suggest that their regulation may represent valid therapeutic target. In addition of mechanistic studies of daclizumab, in other two clinical trials we are trying to understand which mechanisms drive progression of disability and CNS tissue destruction in progressive MS. Primary-progressive MS (PP-MS) is resistant to therapy by immunomodulatory agents. Mitochondrial dysfunction coupled with oxidative stress has been proposed as one of the top alternative hypotheses underlying pathophysiology of PP-MS. Idebenone is a synthetic analogue of coenzyme-Q with lower lipophilicity, which allows its reduction by cytosolic enzymes that are upregulated under oxidative stress, such as NQO1. As such, it can improve mitochondrial metabolism under conditions with dysfunctional ETC complex I. Therefore, in protocol 09-N-0197, we test the hypothesis whether mitochondrial dysfunction and oxidative stress contribute to development of neurological disability in PP-MS. Efficacy of idebenone in suppressing oxidative stress intrathecally and its unexplored immunomodulatory effects are being measured by ex-vivo analysis of PBMC functions and CSF biomarkers in enrolled patients. Rituximab is a B cell depleting chimeric monoclonal Ab and has inhibitory effect on MS disease activity in patients with evidence of blood-brain barrier (BBB) breakdown. The current leading hypothesis is that B cells collaborate with antigen-specific T cells and support T cell activation through antigen-presentation functions and mutual co-stimulation. Furthermore, there is evidence that in secondary-progressive MS (SP-MS) patients B cells and T cells form tertiary lymphoid follicles deep within the brain sulci. These ectopic lymphoid follicles recapitulate activation of antigen-specific T and B cells within the intrathecal compartment. Unfortunately, because majority of progressive MS patients do not have overt BBB disruption, only about 0.1% of systemically administered rituximab gains access to CNS compartment, which is not sufficient to deplete CNS B cells. Therefore, we are testing the hypothesis that intrathecal administration of rituximab in patients with SP-MS will effectively deplete B cells in the CNS compartment and this will translate into therapeutic effect of rituximab on biomarkers of CNS tissue injury in the placebo-controlled, Phase II trial of rituximab in low-inflammatory SP-MS (protocol 10-N-0212).

多发性硬化症（MS）是中枢神经系统（CNS）的炎症性脱髓鞘疾病。 MS的病因尚不清楚，但该疾病在受环境触发因素的遗传易感人群中发展。 长期以来，MS中长期以来的假设暗示了进入中枢神经系统的外围产生的自动反应性T细胞，它们会诱导先前正常神经组织的损伤。 然而，与动物模型实验性自身免疫性脑脊髓炎（EAE）相反，在MS中均未确定免疫反应的靶标或负责CNS损伤的细胞的靶标。此外，某些MS处理的失败针对EAE中CNS组织破坏发展的基础的失败（例如IFN-G，TNF-A抑制剂）表明，不同的机制可能导致MS与EAE的残疾发展。因此，有必要确定针对MS的病理生理机制，但可能无法通过EAE预测。治疗试验，尤其是那些研究新型治疗剂的试验，是研究生物系统特定扰动如何影响MS疾病过程的独特机会。该项目的目的是仔细研究通过在MS中使用新型治疗剂在I/II期临床试验中应用的生物学扰动，以定义中枢神经系统组织损伤的机制，但同样是基于有益的免疫调节和免疫介导的神经保护的机制。通过将生物系统中测得的变化（例如，T细胞或其他免疫细胞亚集的不同功能）与中枢神经系统破坏或修复的结构变化（通过神经影像学模态衡量），并且通过临床结果，我们可以了解哪些生物学过程是有益的，并且在MS的病原体中是有害的。另外，了解其治疗益处是应用疗法的哪些影响将使我们能够定义指示性的生物标志物，理想情况下也可以预测全部治疗反应。我们目前正在研究三种治疗剂的免疫调节特性：Daclizumab，iDebenone和Rituximab在3个研究者引发的I/II期临床试验中，该试验是根据研究新药（IND）应用（PI，Bibiana Bielekova）进行的。我们的结果简要概述以下： Daclizumab是针对CD25的人性化单克隆AB，这是IL-2受体（IL-2R）的α链。 CD25在活化的T细胞上高度上调，并且CD25对高亲和力IL-2信号的贡献对于效应T细胞的扩展至关重要。因此，预计达克珠单抗治疗将导致T细胞功能抑制。虽然我们已经证明达克珠单抗在抑制与MS相关的炎症活性方面非常有效，但这种效果与T细胞的抑制不会平行。取而代之的是，达克珠单抗有选择地扩展了CD56Bright天然杀伤（NK）细胞，并且该人类特异性的NK细胞群具有杀死活化自体T细胞的能力，具有免疫调节功能。 CD56Bright NK细胞利用新机制（Granzyme-K; GZK）杀死T细胞，而GZK表达则通过Daclizumab治疗选择性上调。 CD56Bright NK细胞的扩展与治疗结果相关，暗示它可以用作治疗反应的生物标志物。现在，该观察结果已在MS中的Daclizumab的两个双盲多中心II/IIB试验中完全复制。我们继续研究在MS的DAC-HYP（第二代DACLIZUMAB）在MS的治疗试验中，Daclizumab的作用机理（MOA）（方案10-N-0125），目的是确定达克珠单抗对人免疫系统的所有影响。通过这项工作，我们描述了两个新的MOA，它们还揭示了IL-2生物学的新方面：1。daclizumab通过抑制激活（即成熟的）髓样树突状细胞（MDC）的CD25表达来阻断T细胞的激活。 MDC表达CD25并可以产生IL-2，但由于缺乏另一个重要的单链链CD122而无法消耗它。取而代之的是，MDC使用其CD25将其分泌为免疫突触的超显音IL-2，以以抗原特异性方式激活的T细胞。此IL-2信号与T细胞受体和共刺激刺激结合给出，然后T细胞进入增殖周期并在克隆上扩展。 2。最后，我们最近描述了Daclizumab治疗还通过偏分化其共同前体的分化与促炎性淋巴组织诱导剂（LTI）诱导剂（LTI）细胞以及免疫测试的CD56Bright NK细胞来改变先天淋巴样细胞（ILC）的发展。通过中间亲和力IL-2R促进IL-2信号传导，这种效应是自相矛盾的。此外，我们证明，达氏珠单抗的这种作用使MS患者中循环LTI细胞的水平提高到与健康受试者中观察到的水平相当的水平。因此，我们的数据首次暗示LTI细胞在人体自身免疫性中，并表明其调节可能代表有效的治疗靶标。 除了对达克珠单抗的机理研究，在其他两项临床试验中，我们试图了解哪种机制驱动了渐进式MS中残疾和中枢神经系统组织破坏的进展。原发性MS（PP-MS）对免疫调节剂的治疗有抵抗力。线粒体功能障碍与氧化应激相结合是PP-MS病理生理学基础的最高替代假设之一。 iDebenone是辅酶-Q的合成类似物，具有较低的亲脂性，它允许在氧化应激（例如NQO1）上上调的胞质酶减少其减少。因此，它可以在功能障碍等复合物的条件下改善线粒体代谢。因此，在方案09-N-0197中，我们检验了假设线粒体功能障碍和氧化应激是否有助于PP-MS中神经残疾的发展。伊斯替酮在固定固定及其未开发的免疫调节作用抑制氧化应激方面的功效正在通过对参与患者的PBMC功能和CSF生物标志物进行外部分析来衡量。 利妥昔单抗是一种B细胞耗尽的嵌合单克隆AB，对具有血脑屏障（BBB）细分证据的患者的MS疾病活性具有抑制作用。当前的主要假设是B细胞与抗原特异性T细胞合作，并通过抗原呈递功能和相互共刺激来支持T细胞激活。此外，有证据表明，在次生产生的MS（SP-MS）患者中，B细胞和T细胞形成大脑硫内深处的三级淋巴卵泡。这些异位淋巴卵泡概括了鞘内室内抗原特异性T和B细胞的激活。不幸的是，由于大多数进行性MS患者没有明显的BBB破坏，因此只有大约0.1％的系统施用的利妥昔单抗可以进入CNS室，这不足以消耗CNS B细胞。因此，我们正在测试以下假设：鞘内服用SP-MS患者的利妥昔单抗将有效地耗尽CNS室中的B细胞，这将转化为利妥昔单抗对位于安慰剂控制的SP-SP-SP-SP-MS-0-0-0-0-0-0-0-0-0的治疗作用对CNS组织损伤生物标志物对CNS组织损伤的生物标志物的治疗作用。