Pathophysiology of a Genetic Vascular Disease

 描述（由申请人提供）： 在美国，中风是第四大死亡原因，也是发病的主要原因。尽管在缺血性卒中的预防和治疗方面取得了重大进展，但对出血性卒中的机制和预防知之甚少。我们将使用一种遗传性中风综合征，脑海绵状血管畸形（CCM），研究出血性中风和脑血管疾病的潜在机制。CCM的特征是慢性血管渗漏导致炎症，随后急性出血导致出血性卒中。这项研究将直接和立即应用于超过100，000名估计患有CCM的退伍军人，并有可能影响数百万退伍军人，因为我们的结论更广泛地应用于脑血管疾病。CCM病例的一个重要子集是家族性的，代表了出血性卒中的遗传原因。在这些家族中已经鉴定出三个独立的基因（KRIT 1、OSM和PDCD 10）与CCM相关。这些广泛表达的基因在内皮中是正常血管发育、内皮细胞细胞骨架结构和内皮屏障功能所必需的。特别是，KRIT 1和OSM的缺失导致胚胎、成年小鼠和内皮细胞培养物中非常相似的表型。已经发现KRIT 1和OSM两者作为细胞质蛋白复合物的一部分相互结合，所述细胞质蛋白复合物参与支架小GTP酶，所述小GTP酶参与细胞对应激的反应并控制细胞骨架和屏障功能。主要的内皮信号级联涉及由一氧化氮合酶（eNOS）的内皮同种型产生的一氧化氮（NO），以诱导平滑肌松弛、防止血小板聚集、限制平滑肌增殖和抑制白细胞粘附。成纤维细胞中KRIT 1的缺失导致活性氧（ROS）增加。然而，由于KRIT 1、OSM或PDCD 10的突变，ROS增加是否在CCM的发病机制中起作用尚未确定。重要的是，一些证据表明，与每个CCM基因功能丧失相关的失调信号通路可能是不同的。因此，我们推测，由于CCM蛋白的损失而增加的ROS是CCM中血管病理学的关键贡献者，其可以通过清除过量的超氧化物来拯救，并且作为CCM疾病的下游常见致病机制。这项工作将测试一个重要的功能假设，并澄清一个有前途的潜在治疗目标，在出血性中风综合征，并有可能提供一个路线图，为工作台到床边翻译为人类临床试验在不久的将来。此外，这项工作可以作为未来检查超氧化物清除剂在治疗和预防其他脑血管疾病的基础。该提案对估计患有CCM疾病的10万多名退伍军人具有立即转化的潜力，并将为更广泛影响退伍军人人口的疾病带来更多进展。

 DESCRIPTION (provided by applicant): Stroke is the fourth leading cause of mortality and a major cause of morbidity in the United States. Despite significant progress in the prevention and treatment of ischemic stroke, less is known about mechanisms and prevention of hemorrhagic stroke. We will use a hereditary stroke syndrome, Cerebral Cavernous Malformation (CCM), to study mechanisms underlying hemorrhagic stroke and cerebrovascular disease. CCM is characterized by chronic vascular leak leading to inflammation and by subsequent acute bleeding resulting in hemorrhagic stroke. This study will have direct and immediate application to the more than 100,000 veterans estimated to have CCM, and has significant potential to affect millions of veteran as our conclusions are applied more broadly to cerebrovascular disease. A significant subset of CCM cases is familial and represents a genetic cause for hemorrhagic stroke. Three separate genes have been identified in these families associated with CCM (KRIT1, OSM and PDCD10). These widely expressed genes are required in the endothelium for normal vascular development, endothelial cell cytoskeletal structure, and endothelial barrier function. In particular, the loss f KRIT1 and OSM results in very similar phenotypes in embryos, adult mice, and endothelial cell culture. Both KRIT1 and OSM have been found to bind each other as part of a complex of cytoplasmic proteins involved in scaffolding small GTPases involved in the cellular response to stress and controlling the cellular cytoskeleton and barrier function. A major endothelial signaling cascade involves nitric oxide (NO) produced by an endothelial isoform of nitric oxide synthase (eNOS) to induce smooth muscle relaxation, prevent platelet aggregation, limit smooth muscle proliferation, and inhibit leucocyte adhesion. The loss of KRIT1 in fibroblasts results in increased reactive oxygen species (ROS). However, whether increased ROS plays a role in the pathogenesis of CCM due to mutations in KRIT1, OSM, or PDCD10 has not been established. Importantly, some evidence suggests that the dysregulated signaling pathways associated with loss of function of each CCM gene may be different. Therefore, we hypothesize that increased ROS as a result of the loss of CCM proteins is a key contributor to vascular pathology in CCM, which can be rescued by scavenging excess superoxide, and serves as the downstream common pathogenic mechanism of CCM disease. This work will test an important functional hypothesis and clarify a promising potential therapeutic target in a hemorrhagic stroke syndrome and has the potential to provide a roadmap for bench-to-bedside translation to human clinical trials in the near future. Further, this work may serve as the foundation for future examinations of the use of superoxide scavengers in the treatment and prevention of other cerebrovascular disease. This proposal has both immediate translational potential for more than 100,000 veterans estimated to have CCM disease, and will underlie additional progress for diseases more broadly affecting the Veterans population.