Endothelial Cell Hypoxia Tolerance: Role of Plasmalogens

描述（由申请人提供）：我们已经证明内皮细胞（EC）对急性和慢性缺氧的有害作用具有高度的抵抗力，并且已经从理论上证明，在EC中，与其他耐缺氧生物体或组织一样，多种因素促成了它们卓越的耐缺氧性。在这些潜在的因素中，磷脂原是细胞膜内发现的“乙烯醚”磷脂的一个子集。占人体总磷脂质量的18%已被确定为有效的内源性抗氧化剂。我们已经获得了大量证据表明，在人类和牛的肺动脉EC （HPAEC和BPAEC）以及人脑微血管EC中存在等离子体原，并且等离子体原水平的增加与人类EC对缺氧和活性氧（ROS）的损伤效应的抵抗有关。浆磷脂原保护似乎是应激特异性的，因为浆磷脂原水平升高的HPAEC不能抵御其他常见的细胞应激，如热休克或葡萄糖剥夺。这些发现表明，缩醛磷脂可以帮助EC抵抗特定的细胞应激；为了进一步研究这一假设，我们将：1)通过调节plasmenylcholine含量，建立plasmalogen水平与缺氧暴露时细胞损伤之间的关系，确定plasmalogen在缺氧条件下人类EC存活中的作用；通过测定正常氧合和低氧暴露时的浆醛原损失；通过测定在常氧和低氧条件下的化学分解、浆磷脂原代谢产物和/或浆磷脂原依赖的类二十烷酸产物，来确定浆磷脂原是ROS的清除剂还是第二信使的前体。2)通过比较暴露于缺氧和其他细胞应激（暴露于ROS、氧化还原电位的变化、温度升高、葡萄糖消耗等）时的细胞损伤，确定plasmalogen与细胞氧化剂、细胞氧化酶和抗氧化剂之间的关系，确定人EC plasmalogen含量增加的应激特异性保护作用。一旦弄清了EC中缩醛原的生物化学性质，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.