Endothelial Cell Hypoxia Tolerance: Role of Plasmalogens

描述(申请人提供)：我们已经证明，内皮细胞(EC)对急性和慢性缺氧的损害具有高度的抵抗力，并从理论上推测，在EC中，就像在其他耐缺氧的生物或组织中一样，多种因素导致了它们显著的耐缺氧能力。这些潜在的因素包括血浆原，一种存在于细胞膜中的“乙烯基醚”磷脂的子集，占人类总磷脂质量的0.18%，已被确认为有效的内源性抗氧化剂。我们已经发现大量证据表明，人和牛肺动脉内皮细胞(HPAEC和BPAEC)以及人脑微血管内皮细胞中存在血浆原，并且血浆原水平的升高与人内皮细胞对缺氧和活性氧(ROS)损伤的抵抗力有关。纤溶酶原保护似乎是应激特有的，因为具有更高水平的纤溶酶原的HPAEC不能抵抗其他常见的细胞应激，如热休克或葡萄糖缺乏。为了进一步研究这一假说，我们将：1)确定血浆原水平在缺氧期间内皮细胞存活中的作用：通过调节血浆胆碱含量，建立血浆原水平和缺氧期间细胞损伤之间的关系；通过确定常氧和缺氧期间的血浆原损失；通过确定常氧和缺氧期间血浆原的代谢产物和/或血浆原依赖的二十烷类产物的化学分解，以确定血浆原是作为ROS的清除剂还是作为第二信使的前体。2)通过比较缺氧和其他细胞应激(ROS暴露、氧化还原电位变化、温度升高、葡萄糖耗竭等)对细胞的损伤：确定血浆原与细胞氧化剂、细胞氧化酶和抗氧化剂之间的联系，确定对增加的人EC纤溶酶原含量的应激特异性保护。一旦弄清了EC中血浆原的生物化学，就可以进行确定其生物学重要性的研究。

DESCRIPTION (provided by applicant): We have demonstrated that endothelial cells (EC) are highly resistant to the injurious effects of acute and chronic hypoxia and have theorized that in EC, as in other hypoxia tolerant organisms or tissues, multiple factors contribute to their remarkable hypoxia tolerance. Among these potential factors are plasmalogens, a subset of "vinyl ether" phospholipids that are found within cellular membranes, constitute .18% of the total phospholipid mass in humans and have been identified as potent endogenous antioxidants. We have developed substantial evidence that plasmalogens exist in human and bovine pulmonary artery EC (HPAEC and BPAEC) and human brain microvascular EC and that increased plasmalogen levels correlate with resistance of human EC to the injurious effects of hypoxia and reactive oxygen species (ROS). Plasmalogen protection appears stress specific in that HPAEC with increased levels of plasmalogen are not protected against other common cellular stresses, such as heat shock or glucose deprivation. These findings suggest that plasmalogens can contribute to the protection of EC against specific cellular stresses; to investigate this hypothesis further, we will: 1) Define the role of plasmalogens in human EC survival during hypoxia: by establishing a relationship between plasmalogen levels and cell damage during exposure to hypoxia through modulation of plasmenylcholine content; by determining plasmalogen loss in normoxia and during exposure to hypoxia; by determining chemical breakdown, metabolic products of plasmalogens and/or plasmalogen-dependent eicosanoid products in normoxia and during hypoxia to determine if plasmalogens act as scavengers of ROS or as precursors for second messengers. 2) Define the stress-specific protection of increased human EC plasmalogen content: by comparing cell damage during exposure to hypoxia and other cellular stresses (exposure to ROS, change in redox potential, increased temperature, glucose depletion, etc): by determining the association between plasmalogens and cellular oxidants, cellular oxidases and antioxidants. Once the biochemistry of plasmalogens in EC has been clarified, studies to determine their biological importance can be undertaken.