Mechanisms of hypoxia induced exacerbation of cerebral cavernous malformations

脑海绵状血管畸形(CCM)是常见的由内皮丛形成的神经血管病变 充满了血液，周围是胶质细胞增多症。CCMS影响约1/200儿童和成人，导致终生风险 出血性中风和神经功能障碍，目前尚无有效的药物治疗方法。损失 三个CCM基因的功能突变会推动脑血管的变化。然而，CCM的倾向 病变形成于中枢神经系统(CNS)实质，相对于其他组织尚未完全形成 疾病严重程度的异质性表明环境或生物因素(如其他 基因、神经细胞)起疾病修饰物的作用。我们和其他人已经证明，血管增加 血管内皮生长因子(VEGF)信号转导和相关血管渗漏是CCM的重要因素 疾病。我们的初步数据显示，低氧条件有助于侵袭性发作和进展。 CCM病。我们观察到，缺氧是CCM疾病的促进剂，因为它加剧了 以及CCM动物模型中脑血管病变的大小。我们还观察到小鼠和人CCM组织 结果低氧诱导因子1α(HIF-1a)活性增加，增殖的星形胶质细胞影响 CCM的发病机制。拟议中的研究将检验低氧通过以下途径加重慢性心力衰竭的假设 星形胶质细胞和内皮细胞的低氧程序，导致血管发育异常和中风 到颅内出血。此外，我们假设间歇性低氧(发生在患有 阻塞性睡眠呼吸暂停)会进一步加重慢性阻塞性肺疾病。特定目标1将检验低氧的假设 通过上调小鼠CCM中星形胶质细胞中低氧驱动的基因来加剧CCM的形成。我们会 低氧对星形胶质细胞基因表达(如缺氧程序、血管内皮生长因子)的影响 在星形胶质细胞中纯化EGFP标记的核糖体所获得的翻译的mRNAs 无CCM病变。体外共培养模型将被用来定义CCM之间的相互作用 促进血管功能障碍的内皮细胞和星形胶质细胞。《特定目标2》将检验这一假设 缺氧通过稳定小鼠脑内皮细胞HIF-1a蛋白促进CCM形成 CCM。我们将研究内皮HIF-1a在内皮屏障功能基因变化中的作用 表达、血管内皮生长因子信号转导采用CCM小鼠模型。具体目标3将检验这一假设 间歇性低氧加重小鼠CCM。我们将研究间歇性低氧驱动的CCM的作用 在间歇性低氧下部分恢复夜间活动的CCM小鼠模型的损伤负荷 阻塞性睡眠呼吸暂停(OSA)患者的氧谱。这项拟议的研究可能会导致一种新的 治疗方法(例如，激活的星形胶质细胞和CCM内皮的联合治疗)和 通过定义环境因素(如高海拔)或病理因素(如OSA、 改变氧气水平的慢性肺病)可能是受慢性肺病影响的患者的危险因素。

Cerebral Cavernous Malformations (CCMs) are common neurovascular lesions made of endothelium clusters filled with blood surrounded by gliosis. CCMs affect ~1/200 children and adults, causing a lifetime risk of hemorrhagic strokes and neurologic deficits for which there is no current effective pharmacologic therapy. Loss of function mutations in three CCM genes propels brain vascular changes. However, the propensity of CCM lesions to form in the central nervous system (CNS) parenchyma relative to other tissues has not been fully explained, and the heterogeneity in disease severity suggests that environmental or biological factors (e.g. other genes, neural cells) act as disease modifiers. We and others have demonstrated that increased vascular endothelial growth factor (VEGF) signaling and associated vascular leakage are significant contributors to CCM disease. Our preliminary data show that hypoxic conditions contribute to an aggressive onset and progression of CCM disease. We observed that hypoxia acts as an accelerant of CCM disease by exacerbating the number and size of brain vascular lesions in CCM animal models. We also observed that mouse and human CCM tissue results in increased hypoxia-inducible factor 1 alpha (HIF-1a) activity, and that proliferative astrocytes influence CCM pathogenesis. The proposed study will test the hypothesis that hypoxia exacerbates CCMs through hypoxic programs from astrocytes and endothelium, leading to abnormal vascular development and stroke due to intracranial hemorrhage. Moreover, we hypothesize that intermittent hypoxia (that occurs with patients with obstructive sleep apnea) will further exacerbate CCMs. Specific Aim 1 will test the hypothesis that hypoxia exacerbates CCM formation by elevating hypoxia-driven genes in astrocytes in murine CCM. We will investigate the effect of hypoxia on astrocyte gene expression (e.g., hypoxic program, VEGF) by profiling translated mRNAs obtained from the purification of the EGFP-tagged ribosome in astrocytes in the presence or absence of CCM lesions. Co-culture in vitro models will be used to define the interaction between CCM endothelium and astrocytes that propels vascular dysfunction. Specific Aim 2 will test the hypothesis that hypoxia exacerbates CCM formation by HIF-1a protein stabilization in the brain endothelium in murine CCM. We will investigate the role of endothelial HIF-1a on changes in the endothelial barrier function, gene expression, VEGF signaling using CCM mouse models. Specific Aim 3 will test the hypothesis that intermittent hypoxia exacerbates murine CCM. We will investigate the role of intermittent hypoxia-driven CCM lesion burden, using mouse models of CCM under intermittent hypoxia that partially recapitulates nocturnal oxygen profile in patients with obstructive sleep apnea (OSA). The proposed research may lead to a new therapeutic approach (e.g., combination therapies for activated astrocytes and CCM endothelium) and preventive measures by defining how environmental (e.g., high altitude) or pathological factors (e.g., OSA, chronic lung disease) that alter oxygen levels may act as risk factors for patients affected with CCMs.