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损伤作用具有高度抵抗力，并从理论上证明，在EC中，与其他耐缺氧生物体或组织一样，多种因素有助于其显著的耐缺氧性。在这些潜在因素中，有缩醛磷脂，一种在细胞膜内发现的“乙烯基醚”磷脂的子集，占人体总磷脂质量的0.18%，已被鉴定为有效的内源性抗氧化剂。我们已经开发了大量的证据表明，缩醛磷脂存在于人类和牛肺动脉EC（HPAEC和BPAEC）和人脑微血管EC和增加的缩醛磷脂水平与人类EC的耐缺氧和活性氧（ROS）的有害影响。缩醛磷脂保护似乎是应激特异性的，因为具有增加的缩醛磷脂水平的HPAEC不受其他常见细胞应激（如热休克或葡萄糖剥夺）的保护。这些发现表明，缩醛磷脂可有助于保护EC免受特定的细胞应激;为了进一步研究这一假设，我们将：1）确定缩醛磷脂在缺氧期间人EC存活中的作用：通过调节血浆胆碱含量建立缩醛磷脂水平与缺氧暴露期间细胞损伤之间的关系;通过测定常氧和缺氧暴露期间缩醛磷脂的损失;通过测定在常氧和低氧期间的缩醛磷脂的化学分解、代谢产物和/或缩醛磷脂依赖性类花生酸产物，以确定缩醛磷脂是否充当ROS的清除剂或第二信使的前体。2)通过比较暴露于缺氧和其他细胞应激（暴露于ROS、氧化还原电位变化、温度升高、葡萄糖消耗等）期间的细胞损伤：通过确定缩醛磷脂与细胞氧化剂、细胞氧化酶和抗氧化剂之间的关联，定义增加的人EC缩醛磷脂含量的应激特异性保护。一旦EC中缩醛磷脂的生物化学被阐明，就可以进行研究以确定其生物学重要性。

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.