Role of Tau Conformations in Vascular Contribution to Cognitive Impairment and Dementia

科学证据继续支持血管对认知障碍和痴呆(VCID)的贡献 例如阿尔茨海默病(AD)。事实上，大约50%的痴呆症患者有混合的血管和AD病理 在他们的大脑里。在许多潜在的临床触发因素中，多发栓塞性脑梗塞和脑低灌注， 特别是在存在衰老和高血压的情况下，是VCID的主要血管因素，称为血管 痴呆症(VAD)，但潜在的机制仍然难以捉摸。值得注意的是，神经原纤维缠结由 过度磷酸化tau是阿尔茨海默病的一个神经病理特征，但单纯的vad人类大脑没有。 明显的tau病理纠缠在一起，因此人们对tau病理在VaD发生发展中的作用知之甚少。 最近，我们发现了一种独特的Prolyl异构酶Pin1，它可以防止 致病顺式构象中tau(P-tau)中的磷酸化Thr231-Pro基序，但在AD中被 老化、氧化等。顺式P-tau是一种以前不为人知的tau病理先兆，它煽动和 传播与AD和创伤性脑损伤(TBI)相关的神经退行性变和痴呆，但可以 被顺式单抗阻断。在我们的初步研究中，我们在神经血管单位细胞中发现了强大的顺式P-tau，而不存在tau缠结。 纯vad人脑和小鼠模型多发栓塞性脑梗塞或脑低灌流后的病理学。 此外，纯化的顺式P-tau对神经元和脑微血管内皮细胞都有毒性，而且 引起小鼠脑功能障碍，两者均可被顺式单抗有效阻断。此外，顺式单抗 阻断缺氧或血清耗竭诱导血管内皮细胞顺式P-tau和细胞死亡 神经元在体外和修复白质和灰质损伤以及重复性脑损伤后小鼠的神经功能缺陷。 在这项提议中，我们组建了一个拥有所有必要专业知识的团队来测试我们的新假设 在衰老过程中，血管损伤会导致氧化应激使Pin1失活，从而导致顺式作用的积累。 P-tau破坏神经血管单位，从而成为VaD的早期和可用药的驱动因素。我们会 首次评估Pin1抑制和顺式P-tau在不同神经血管单位细胞中的诱导及其相互关系 脑血管病变和脑白质病变，以及在多发栓塞性脑梗塞或 有或没有高血压或Pin1基因敲除的年轻和老年小鼠的脑低灌流。到时候我们会的 VaD人脑和小鼠脑组织中顺式P-tau蛋白的纯化及其生化性质 在体外和体内损伤神经血管单位细胞以诱导白质损伤的性质和能力 与vaD相关的神经缺陷。最后，我们将评估顺式单抗对神经血管的抑制作用。 体外单位损伤和修复白质损伤、延迟性神经变性和神经功能缺失 在老年高血压或Pin1基因敲除小鼠的多栓子梗塞或脑低灌流后。这些 研究应该有助于我们确定顺式P-tau是VCID的早期疾病驱动因素，揭示一个共同的分子 血管和AD病理的潜在机制，并寻求针对这些重大疾病的靶向治疗。

Scientific evidence continues to support vascular contributions to cognitive impairment and dementia (VCID) such as Alzheimer's disease (AD). In fact, ~50% of dementia patients have mixed vascular and AD pathologies in their brains. Among many potential clinical triggers, multi-embolic infarcts and cerebral hypoperfusion, especially in the presence of aging and hypertension, are major vascular factors in VCID, referred as vascular dementia (VaD), but underlying mechanisms remain elusive. Notably, neurofibrillary tangles composed of hyperphosphorylated tau are a neuropathological hallmark of AD, but pure VaD human brains do not have obvious tau tangle pathology so that little is known about the role of tau pathology in the development of VaD. Recently, we have identified a unique prolyl isomerase, Pin1 that prevents accumulation of the phosphorylated Thr231-Pro motif in tau (P-tau) in the pathogenic cis conformation, but is inactivated in AD by aging, oxidation and others. Cis P-tau is a previously unknown precursor of tau pathology that instigates and propagates neurodegeneration and dementia associated with AD and traumatic brain injury (TBI), but can be blocked by cis mAb. In our pilot studies, we found robust cis P-tau in neurovascular unit cells without tau tangle pathology in pure VaD human brains and mouse models after multi-embolic infarcts or cerebral hypoperfusion. Furthermore, purified cis P-tau was toxic both to neurons and brain microvascular endothelial cells and also caused brain dysfunction in mice, both of which were effectively blocked by cis mAb. Moreover, cis mAb blocked hypoxia or serum depletion from inducing cis P-tau and cell death in vascular endothelial cells and neurons in vitro and restored white and gray matter lesions and neurologic deficits after repetitive TBI in mice. In this proposal, we have assembled a team with all the requisite expertise to test our novel hypothesis that during aging, vascular insults lead to oxidative stress that inactivates Pin1, resulting in accumulation of cis P-tau that damages the neurovascular unit, thereby serving as an early and druggable driver of VaD. We will first assess Pin1 inhibition and cis P-tau induction in different neurovascular unit cells, and their relationships with vascular pathology and white matter lesions in VaD human brains and after multi-embolic infarcts or cerebral hypoperfusion in young and old mice with or without hypertension or Pin1 knockout. We will then purify cis P-tau proteins from VaD human brains and VaD mouse brains to characterize their biochemical property and ability to damage neurovascular unit cells in vitro and in vivo to induce white matter lesions and neurologic deficits relevant to VaD. Finally, we will evaluate the efficacy of cis mAb in inhibiting neurovascular unit damage in vitro and restoring white matter lesions, delayed neurodegeneration and neurologic deficits after multi-embolic infarcts or cerebral hypoperfusion in aged hypertensive or Pin1 knockout mice. These studies should help us identify cis P-tau as an early disease driver of VCID, uncover a common molecular mechanism underlying vascular and AD pathologies, and pursue targeted therapy for these major diseases.