Heterochronic Blood Exchange Inhibits α?Synucleinopathy through Modulating Plasma Protein's Mediation on Pathological α?Synuclein Spreading

项目总结 衰老是导致α-SYN的最大危险因素，它是一组神经退行性疾病，具有严重的认知功能障碍和进行性运动功能障碍和痴呆，如帕金森氏病、路易体痴呆、帕金森氏病伴痴呆和一半的阿尔茨海默病患者。痴呆是α-突触核病的常见症状：痴呆是仅次于阿尔茨海默病(AD)的第二大常见痴呆，占痴呆病例的30%；约30%的AD患者还患有α-突触核病，导致的认知功能下降比单独使用AD更快、更严重。帕金森病是第二大常见的神经退行性疾病，超过50%的帕金森病患者发展为PDD。除了认知和记忆功能障碍外，痴呆症患者还会出现焦虑、抑郁和情绪波动。虽然α-SYN病理与痴呆高度相关，但推动其发病并促进其进展的潜在衰老相关机制尚不清楚，目前还没有可用的疾病调整治疗方法。基于大量的尸检分析，Braak等人。证明了α-SYN病理以一种刻板印象的方式从迷走神经扩散到大脑，可能始于胃肠道。尤其是，几乎所有的十二指肠系膜瘤和十二指肠系膜病都表现为肠道α-SYN病理。临床和实验观察都支持致病的α-SYN传播是驱动α-SYN病的主要触发因素。在我们建立的肠脑α-突触核蛋白病小鼠模型中，肠道注射致病α-突触核蛋白(α-SYN)可以概括α-SYN病理肠脑扩散和认知功能障碍。在我们的初步研究中，来自年轻小鼠的异慢性血液交换抑制了老年小鼠致病性α-SYN的传播和神经炎症，表明HBE转移的表型可能有效地抑制α-突触核病症。我们鉴定了淋巴细胞激活基因3(LAG3)1，它是病理性α-SYN传播的主要受体。为了确定返老还童和加速衰老事件的机制，我们进一步鉴定了两个新的与LAG3相关的调节衰老的蛋白，它们可以介导致病性α-SYN的传播。我们的研究支持通过HBE方法调节老年小鼠血浆FGL1和sLAG3水平的可行性。为了确定血浆中FGL1和sLAG3是否是HBE抑制α-突触核病和相关认知障碍所必需的分子介质的潜在机制，我们建立了一套严格而稳健的实验系统，结合HBE方法、GBAS模型、不含这些因素的基因工程小鼠以及重组FGL1和sLAG3蛋白，用于全面的得失功能分析。我们的中心假设是确定HBE通过FGL1和SLAG3抑制α-突触核病症和相关认知障碍的潜在机制。FGL1作为一种再生因子，抑制病理性α-SYN在肠道-脑轴的扩散，减轻随之而来的神经变性、神经炎症和认知障碍。SLAG3是参与FGL1发病的年龄加速因子，对FGL1具有拮抗作用。引人注目的是，人类尸检证据表明，α-SYN病理首先在胃肠道系统观察到，然后以一种刻板印象的方式传播到大脑。最近，我们的合作者Dawson博士开发了一种新的肠脑α-突触核病模型，这是一种散发性α-突触核病模型，它概括了患者多个器官和大脑区域之间的病理性α-SYN扩散。然而，与衰老相关的血液成分如何调节α-突触核病症在很大程度上仍不清楚。作为本项目的基础，我们鉴定了α-SYN病理性传播的主要受体-淋巴细胞激活基因3(LAG3)。我们的初步结果表明，幼年小鼠的异慢性血液交换可以抑制病理性α-SYN向细胞的传播和老年小鼠的炎症。我们进一步确定了两种调节LAG3介导的病理性α-SYN传播的血液衰老调节蛋白。血浆第一蛋白纤维蛋白原样蛋白(FGL1)作为LAG3的主要抑制配体，随着年龄的增长而减少，并抑制α-SYN的传递。第二种血浆蛋白sLAG3是LAG3蛋白的可溶性形式，随着年龄的增长而增加，并促进α-SYN的传递。我们的研究还支持使用HBE方法通过年轻小鼠的血液调节老年小鼠血浆FGL1和sLAG3水平的可行性。 我们的中心假设是，年轻血液的HBE通过两种与衰老相关的循环蛋白(FGL1和SLAG3)抑制α-突触核病，FGL1和SLAG3对于LAG3介导的病理性α-SYN传递至关重要。FGL1作为一种恢复因子，抑制病理性α-SYN在肠道-脑轴的扩散，以及由此引起的与α-突触核病相关的神经变性、神经炎症和行为缺陷。SLAG3是一种年龄加速因子，对FGL1具有拮抗作用。在具体目标1中，我们建议确定HBE是否通过增加衰老减少的FGL1来抑制病理性α-SYN的扩散来改善α-SYN病和相关的认知障碍。在具体目标2中，我们建议确定HBE是否通过减少衰老诱导的SLAG3来抑制病理性α-SYN的传播来改善α-SYN病和相关的认知障碍。调节血浆因子是抑制病理性α-SYN传播、治疗α-突触核病和痴呆的一种新策略。这项研究的积极结果将证明基于血浆因子调节的新型α-突触核病治疗方法的开发是合理的。来自该项目的新的分子洞察力将为基于FGL1和sLAG3调制的α-突触核病治疗的优化和临床翻译奠定坚实的基础。

PROJECT SUMMARY Aging is the greatest risk factor to α-synucleinopathy, a group of neurodegenerative diseases with severe cognitive impairmentand progressive motor dysfunction and dementia, such as Parkinson's disease (PD), dementia with Lewy bodies (DLB) and Parkinson's disease with dementia (PDD) and half of Alzheimer's disease patients (AD). Dementia is a common symptom in α-synucleinopathies: DLB is the 2nd most common dementia after Alzheimer's disease (AD) accounting for 30% of dementia cases; Around 30% of AD cases also suffer from α-synucleinopathy resulting in a more rapid and severe cognition decline than AD alone. PD is the 2nd most common neurodegenerative disease, and greater than 50% of PD cases develop PDD. In addition to cognitive and memory dysfunctions, patients with dementia also suffer from anxiety, depression and mood swings. Although α-syn pathology is highly associated with dementia, the underlying aging-related mechanism driving the pathogenesis and contributing to their progression is not known and there is no available disease modifying therapy yet. Based on substantial postmortem analysis, Braak et al. demonstrated that α-syn pathology spreads in a stereotyped fashion from the vagus to the brain, which may initiate in the gastrointestinal tract. Particularly, nearly all the DLB and PDD cases present with α-syn pathology in the gut. Both clinical and experimental observations support that pathogenic α-syn spreading is a master trigger that drives α-synucleinopathy. In our gut-brain α-synucleinopathy (GBAS) mouse model, gut-injection of pathogenic α-synuclein (α-syn) can recapitulate α-syn pathology gut-brain spreading and cognitive impairment. In our preliminary studies, heterochronic blood exchange (HBE) from young mice inhibited pathogenic α-syn transmission and neuroinflammation in aged mice, suggesting an HBE-transferred phenotype that may effectively inhibit α-synucleinopathy. We identified lymphocyte-activation gene 3 (LAG3)1, a major receptor of pathologic α-syn transmission. To identify the mechanism underlying rejuvenation and accelerated aging event, we further identified two novel LAG3-related and aging-regulating proteins that can mediate pathogenic α-syn transmission. Our studies support the feasibility to modulate plasma levels of FGL1 and sLAG3 in aged mice by the HBE approach. To determine the underlying mechanism if FGL1 and sLAG3 in the plasma are molecular mediators essential for the inhibitory effects of HBE on α-synucleinopathy an d related cognitive impairment, we have established a rigorous and robust experimental system combining the HBE approach, the GBAS model, genetically engineered mice without these factors, and recombinant FGL1 and sLAG3 proteins, for comprehensive gain- and loss-of-function analysis. Our Central Hypothesis is to identify the underlying mechanism that HBE inhibits α-synucleinopathy and related cognitive impairment through FGL1 and sLAG3. FGL1 functions as a rejuvenation factor to inhibit pathologic α-syn spreading in the gut-brain axis and alleviate consequent neurodegeneration, neuroinflammation, and cognitive impairment. sLAG3 acts as an age-acceleration factor contributing to the pathogenesis and with antagonistic function to FGL1. Strikingly, human postmortem evidence shows that α-syn pathology is observed first in the gastrointestinal system and then spreads to the brain in a stereotyped fashion. Recently, our collaborator Dr. Dawson developed a novel Gut-Brain α-synucleinopathy (GBAS) model, a sporadic α-synucleinopathy model recapitulating pathologic α-syn spreading among multiple organs and brain regions in patients. However, it remains largely unknown how aging-associated blood-borne components modulate α-synucleinopathy. As the foundation of this project, we identified lymphocyte-activation gene 3 (LAG3), a major receptor of pathologic α-syn transmission. Our preliminary results showed that heterochronic blood exchange (HBE) from young mice can inhibit pathologic α-syn transmission to cells and inflammation in aged mice. We further identified two blood-borne aging-modulated proteins that regulate LAG3-mediated pathologic α-syn transmission. The first plasma protein fibrinogen-like protein (FGL1) as the major inhibitory ligand of LAG3, is decreased by aging and inhibits α-syn transmission. The second plasma protein sLAG3 is the soluble form of LAG3 protein, and it is increased by aging and promotes α-syn transmission. Our studies also support the feasibility to use HBE approach to modulate plasma levels of FGL1 and sLAG3 in aged mice by young blood. Our Central Hypothesis is that HBE with young blood inhibits α-synucleinopathy through two aging-associated circulatory proteins (FGL1 and sLAG3) essential for LAG3-mediated pathologic α-syn transmission. FGL1 functions as a rejuvenation factor to inhibit pathologic α-syn spreading in the gut-brain axis and consequent neurodegeneration, neuroinflammation, and behavioral deficits associated α-synucleinopathy. sLAG3 acts as an age-acceleration factor with antagonistic functions to FGL1. In specific aim 1, we propose to determine if HBE ameliorates α-synucleinopathy and related cognitive impairment by increasing aging-reduced FGL1 to inhibit pathological α-syn spreading. In specific aim 2, we propose to determine if HBE ameliorates α-synucleinopathy and related cognitive impairment by decreasing aging-induced sLAG3 to inhibit pathological α-syn spreading. Modulating plasma factors is a novel strategy to inhibit pathologic α-syn spreading and treating α-synucleinopathy and dementia. Positive results from this study will justify the development of novel α-synucleinopathy therapies based on plasma factor modulation. Novel molecular insights from this project will lay a solid foundation for the optimization and clinical translation of α-synucleinopathy therapies based on FGL1 and sLAG3 modulation.