Pathophysiology of a Genetic Vascular Disease

 描述(由申请人提供)： 在美国，中风是第四大致死原因，也是致病的主要原因。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，脑海绵状畸形(CCM)来研究出血性中风和脑血管疾病的发病机制。CCM的特点是慢性血管渗漏导致炎症和随后的急性出血导致出血性中风。这项研究将直接和立即应用于估计患有CCM的10万多名退伍军人，并具有巨大的潜力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病例中的一个重要亚组是家族性的，代表了出血性中风的遗传原因。在这些与CCM相关的家族中，已发现三个独立的基因(KRIT1、OSM和PDCD10)。这些广泛表达的基因在内皮细胞中是正常血管发育、内皮细胞骨架结构和内皮屏障功能所必需的。特别是，KRIT1和OSM的缺失导致胚胎、成年小鼠和内皮细胞培养中的表型非常相似。KRIT1和OSM都被发现作为细胞质蛋白复合体的一部分相互结合，该复合体参与支撑参与细胞对应激反应的小GTP酶，并控制细胞细胞骨架和屏障功能。一个主要的内皮信号级联反应涉及由内皮型一氧化氮合酶(ENOS)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，并抑制白细胞黏附。成纤维细胞中KRIT1的缺失导致活性氧(ROS)的增加。然而，由于KRIT1、OSM或PDCD10的突变，ROS增加是否在CCM的发病机制中起作用还没有确定。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CCM蛋白丢失导致的ROS增加是CCM血管病理的关键因素，清除过量的超氧化物可以挽救CCM的血管病理，并可能是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说，并阐明出血性中风综合征的一个有前景的潜在治疗靶点，并有可能在不久的将来为从工作台到床边的转换到人类临床试验提供路线图。此外，这项工作可作为未来超氧化物清除剂在治疗和预防其他脑血管疾病中使用的检查的基础。这项提案对估计患有CCM病的10万多名退伍军人具有直接的翻译潜力，并将为更广泛地影响退伍军人人口的疾病取得更多进展奠定基础。

 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.