Progressive Post Stroke Cognitive Impairment:Mechanisms & Intervention

摘要：血管性认知障碍/痴呆(VCID)是卒中最严重的致残性后果之一，发病率为12%-48%。在卒中死亡率下降的同时，卒中后VCID的比率在1990至2000年间几乎翻了一番，增加了这一领域治疗开发的紧迫性。在开发新的治疗策略方面取得进展的一个关键障碍是缺乏对中风后VCID如何发展的了解。在实验性中风研究中几乎完全使用雄性和健康的动物，扩大了这一知识差距。我们令人兴奋的初步数据显示，实验性中风后认知功能逐渐恶化，高血压和糖尿病等并存疾病的存在加剧了这种损害。我们还显示存在延长的治疗窗口来预防VCID。来自RECES研究的最新数据显示，中风患者在单一病变中风后也经历了进行性认知能力下降，这促使我们重新思考如何治疗VCID。因此，这项提议的目标是定义导致中风后认知障碍慢性积累的细胞机制。基于我们发表的和试点数据的强有力的科学前提，我们的中心假设是，当中风叠加共病时，进行性认知能力下降是严重的，涉及小胶质细胞激活，导致成熟脑源性神经营养因子(MBDNF)信号减少和神经血管单位的重塑。我们进一步假设，血管紧张素II受体(AT2)的刺激破坏了这种永久的炎症循环，并阻止了进行性的VCID。3个综合的翻译和机械目标将检验这些假说；目标1：卒中后的进行性认知障碍，在共病条件下得到增强，可以作为治疗的靶点。目的2：卒中后的小胶质细胞在疾病状态下被激活为类M1表型，放大BDNF信号的失调，导致NVU重塑，最终导致进展性VCID。目的：AT2刺激通过促进NVU细胞M2样小胶质细胞的激活和BDNF信号的恢复来预防进展性VCID。在超过5年的10项研究中，我们将利用对老年、高血压和糖尿病动物的严格行为评估、药物和遗传操作、新的获得和丧失功能的方法以及体外评估，促进我们对VCID的治疗的理解，VCID是一种未被充分研究但具有破坏性的缺血性中风后果。

ABSTRACT: Vascular cognitive impairment /dementia (VCID) is one of the most disabling consequences of stroke, occurring in 12%-48% of patients. At a time when stroke mortality is decreasing, the rate of VCID after stroke almost doubled between 1990 and 2000, increasing the urgency for treatment development in this area. A critical barrier to progress in the development of new therapeutic strategies is the lack of understanding of how VCID develops after stroke. The use of almost exclusively male and healthy animals in experimental stroke research has widened this gap in knowledge. Our exciting preliminary data demonstrated a progressive deterioration of cognitive function after experimental stroke, an impairment accentuated by the presence of comorbid diseases such as hypertension and diabetes. We also show the presence of an extended therapeutic window to prevent VCID. Recent data from the REGARDS study showed that stroke patients also experience a progressive cognitive decline after a single lesion stroke, causing us to rethink how we approach VCID therapeutically. Accordingly, the goal of this proposal is to define the cellular mechanisms contributing to the chronic build-up of cognitive deficits after stroke. Based on the strong scientific premise of our published and pilot data, our central hypothesis is that progressive cognitive decline is profound when stroke is superimposed on comorbid diseases and involves microglial activation leading to decreased mature brain derived neurotrophic factor (mBDNF) signaling and remodeling in the neurovascular unit. We further hypothesize that Angiotensin type II receptor (AT2) stimulation disrupts this perpetual inflammatory loop and prevents progressive VCID. 3 integrated translational and mechanistic aims will test these hypotheses; Aim 1: progressive cognitive deficits after stroke, augmented in comorbid conditions, CAN be therapeutically targeted. Aim 2: microglia that are activated to M1-like phenotype after stroke in comorbid disease states, amplify dysregulation of BDNF signaling leading to NVU remodeling and ultimately, progressive VCID. Aim 3: AT2 stimulation prevents progressive VCID by promoting M2-like microglial activation and restoration of BDNF signaling in NVU cells. In 10 studies over 5 years, and utilizing rigorous behavioral assessment of aged, hypertensive, and diabetic animals, pharmacologic and genetic manipulation, novel gain and loss-of-function approaches, as well as in vitro assessment, we will advance our understanding of the treatment of VCID, an understudied yet devastating consequence of ischemic stroke.