Calcineurin and inflammatory signaling processes in aging and Alzheimer's Disease

摘要(摘自原拨款建议书) 越来越多的证据表明，并存的血管对认知障碍和 痴呆症(VCID)可能会使阿尔茨海默病(AD)相关痴呆的治疗复杂化。我们的 最重要的假设是AD和VCID的病理后遗症在激活的水平上汇聚 星形胶质细胞，为广泛的痴呆症(即单独的AD，单独的VCID， 和混合性痴呆)。这一假说的核心是钙依赖的磷酸酶，钙调神经磷酸酶(CN)，它 在激活的星形胶质细胞中高水平出现，并正向调节 通过与NFAT转录因子直接相互作用激活星形胶质细胞表型。我们和其他人 研究表明，在认知衰退的早期阶段，星形胶质细胞中存在CN/NFAT的过度激活 在患有AD样病理的人类和小鼠中，并与谷氨酸依赖的过度兴奋性有关。 然而，在VCID中对星形细胞CN/NFAT知之甚少，在我们的 对混合性痴呆的认识。 从人类脑血管病理病例和已建立的 基于饮食的VCID小鼠模型，提示过度活跃的CN/NFAT信号也与脑血管有关 病理学。基于这些观察，我们预测AD和VCID联合病理将 加剧CN/NFAT信号异常导致神经毒性星形胶质细胞表型，其特征是 EAAT2/GLT-1谷氨酸转运体缺失和谷氨酸摄取受损。我们进一步预测， 使用细胞型特异性AAV载体和新的药理作用使CN/NFAT/GLT-1轴正常化 药物将减轻AD、VCID和混合性AD/VCID的神经元和脑血管异常 模特们。我们的主要假设和推论预测将用人类生物样本进行检验。 以及相关的小鼠模型，包括VCID的高同型半胱氨酸血症(HHcy)模型和5xFAD 病理模型。Aim 1将检验这一假设，即在两个人类中混合了AD和VCID的病理 而小鼠聚集在一起加剧星形胶质细胞中CN/NFAT的过度活动，导致神经毒性星形胶质细胞 分子表型。目标2将验证星形细胞CN/NFAT/GLT-1轴驱动的假设 AD、VCID和混合VCID/AD模型中的脑血管功能障碍。而《目标3》将测试 假设星形胶质细胞CN/NFAT/GLT-1轴驱动过度兴奋、突触功能障碍和 AD、VCID和混合VCID/AD模型中的认知损失。这些目标将通过小说来实现 试剂和前沿的多学科方法。这项工作对于评估 星形细胞CN/NFATs在VCID和混合病理中的作用，并可能有助于刺激星形胶质细胞的发育- 有针对性地治疗范围广泛的痴呆症病例。

Abstract (FROM ORIGINAL FUNDED PROPOSAL) Mounting evidence suggests that comorbid vascular contributions to cognitive impairment and dementia (VCID) may complicate the treatment of Alzheimer’s disease (AD)-related dementia. Our overarching hypothesis is that AD and VCID pathological sequelae converge at the level of activated astrocytes, providing a common druggable target for a wide range of dementias (i.e. AD alone, VCID alone, and mixed dementia). Central to this hypothesis is the Ca2+ -dependent phosphatase, calcineurin (CN), which appears at high levels in activated astrocytes and positively regulates multiple components of the activated astrocyte phenotype through direct interactions with NFAT transcription factors. We, and others have shown that hyperactivation of CN/NFAT occurs in astrocytes during early stages of cognitive decline in humans and mice with AD-like pathology and is linked to glutamate-dependent hyperexcitability. However, little is known about astrocytic CN/NFAT in VCID, presenting a critical knowledge gap in our understanding of mixed dementia. New preliminary data obtained from human cerebrovascular pathology cases and from an established diet-based VCID mouse model, suggest that hyperactive CN/NFAT signaling also arises with cerebrovascular pathology. Based on these observations, we predict that combined AD and VCID pathology will exacerbate aberrant CN/NFAT signaling leading to a “neurotoxic” astrocyte phenotype, characterized by the loss of EAAT2/Glt-1 glutamate transporters and impaired glutamate uptake. We further predict that normalization of the CN/NFAT/Glt-1 axis, using cell-type specific AAV vectors and novel pharmacologic agents, will alleviate neuronal and cerebrovascular abnormalities in AD, VCID, and mixed AD/VCID models. Our overarching hypothesis and corollary predictions will be tested using human biospecimens and relevant mouse models including the hyperhomocysteinemia (HHcy) model of VCID and the 5xFAD model of A pathology. Aim 1 will test the hypothesis that mixed AD and VCID pathologies in both humans and mice converge to exacerbate CN/NFAT hyperactivity in astrocytes, leading to a neurotoxic astrocyte molecular phenotype. Aim 2 will test the hypothesis that the astrocytic CN/NFAT/Glt-1 axis drives cerebrovascular dysfunction in AD, VCID, and mixed VCID/AD models. And Aim 3 will test the hypothesis that the astrocytic CN/NFAT/Glt-1 axis drives hyperexcitability, synapse dysfunction, and cognitive loss in AD, VCID, and mixed VCID/AD models. These aims will be pursued using novel reagents, and cutting-edge multidisciplinary approaches. This work is essential for assessing the role of astrocytic CN/NFATs in VCID and mixed pathology and may help stimulate the development of astrocyte- targeted approaches for treating a broad range of dementia cases.