STAT3 activation in astrocytes as a driver of neurovascular dysfunction in Alzheimer's disease and related dementias

项目摘要 阿尔茨海默病（AD）和相关痴呆（ADRD）因神经血管功能障碍而恶化。 星形胶质细胞是神经血管健康和血脑屏障（BBB）功能的关键贡献者。响应于 在病原性刺激下，星形胶质细胞采用通常以形态学变化为特征的“反应性”表型。 最近的研究表明，反应性星形胶质细胞可以采用不同的分子特性谱，但 这些不同亚型的反应性星形胶质细胞和脑血管系统之间的相互作用仍不清楚。 事实上，一些研究表明，反应性星形胶质细胞对BBB功能有负面影响，而另一些研究则表明， 表明反应性星形胶质细胞对损伤后的神经血管修复至关重要。大多数研究都是 在中风或身体创伤的背景下进行，虽然有一些新兴的研究在单细胞 关于ADRD中反应性星形胶质细胞状态的分辨率，很少或没有关于这些不同状态如何 可能直接导致神经血管功能障碍。在此，我们建议研究STAT 3激活如何 导致ADRD中的神经血管功能障碍。在初步工作中，使用来自 通过尸检人脑组织，我们发现AD患者的脑组织中 STAT 3激活的星形胶质细胞和发炎的血管。在星形胶质细胞的人体外模型中， 脑内皮细胞，我们已经表明，炎症刺激激活STAT 3信号在星形胶质细胞， 导致BBB破坏，而抑制星形胶质细胞中的STAT 3活化可减轻这些结果。此外，本发明还 使用人体外模型、离体小鼠皮质切片培养物和体内操作的组合， 我们已经证明，α 1-抗糜蛋白酶（ACT）--一种由STAT 3调节的丝氨酸蛋白酶--有助于 直接导致神经血管功能障碍展望未来，我们将在这些有希望的成果的基础上， 方式在目标1中，我们将把我们的人体组织研究扩展到更大的ADRD队列，并采用先进的 成像技术来量化STAT 3激活的星形胶质细胞和 血管损伤部位。在目标2中，我们将在转基因小鼠模型中抑制星形胶质细胞中的STAT 3信号传导。 并评价神经血管功能障碍的纵向变化;这些评估将包括 单细胞RNA测序以表征沿整个血管树沿着内皮细胞的分子变化。 在目标3中，我们将在转基因小鼠模型中将星形胶质细胞源性ACT与神经血管功能障碍联系起来 ADRD，以及表征ACT和APOE之间的前瞻性协同作用， AD和痴呆风险之间的联系。总的来说，这项工作的成果将确定以下机制的作用： STAT 3激活的星形胶质细胞在与ADRD相关的神经血管功能障碍中的作用，并确定潜在的途径 用于靶向星形胶质细胞作为ADRD治疗策略。

Project summary Alzheimer’s disease (AD) and related dementias (ADRD) are exacerbated by neurovascular dysfunction. Astrocytes are key contributors to neurovascular health and blood-brain barrier (BBB) function. In response to pathogenic stimuli, astrocytes adopt a “reactive” phenotype generally characterized by morphological changes. Recent research has shown that reactive astrocytes can adopt a diverse spectrum of molecular identities, but the interplay between these different subtypes of reactive astrocytes and the brain vasculature remains unclear. Indeed, some studies have shown that reactive astrocytes negatively influence BBB function, while others have shown that reactive astrocytes are vital to neurovascular repair after injury. Most of these studies have been performed in the context of stroke or physical trauma, and while there are some emerging studies at single-cell resolution on reactive astrocyte states in ADRDs, there is little to no information on how these different states may directly contribute to neurovascular dysfunction. Herein, we propose to investigate how STAT3 activation in astrocytes drives neurovascular dysfunction in ADRDs. In preliminary work, using thin sections from postmortem human brain tissue, we have shown that AD patients have significantly increased numbers of STAT3-activated astrocytes and inflamed blood vessels. In a human in vitro model of astrocytes cocultured with brain endothelial cells, we have shown that inflammatory stimuli activate STAT3 signaling in astrocytes, which leads to BBB disruption, and inhibition of STAT3 activation in astrocytes mitigates these outcomes. Further, using combinations of the human in vitro model, ex vivo mouse cortical slice cultures, and in vivo manipulations, we have shown that alpha 1-antichymotrypsin (ACT)—a STAT3-regulated serine protease inhibitor—contributes directly to neurovascular dysfunction. Moving forward, we will build on these promising results in the following manner. In Aim 1, we will expand our human tissue studies into larger ADRD cohorts and employ advanced imaging techniques to quantify three-dimensional spatial relationships between STAT3-activated astrocytes and sites of vascular damage. In Aim 2, we will inhibit STAT3 signaling in astrocytes within transgenic mouse models of ADRD and evaluate longitudinal alterations to neurovascular dysfunction; these assessments will include single-cell RNA sequencing to characterize molecular changes to endothelial cells along the entire vascular tree. In Aim 3, we will causally link astrocyte-derived ACT to neurovascular dysfunction in transgenic mouse models of ADRD, as well as characterize prospectively synergy between ACT and APOE, which have known connections in AD and dementia risk. Collectively, outcomes from this work will define the mechanistic roles of STAT3-activated astrocytes in neurovascular dysfunction associated with ADRD and identify potential avenues for targeting astrocytes as an ADRD treatment strategy.