Tarng D C, Huang T P, Wei Y H, Liu T Y, Chen H W, Wen Chen T, Yang W C
Institute of Clinical Medicine and the Department of Biochemistry and Center for Cellular and Molecular Biology, National Yang-Ming University, Taipei, Taiwan.
Am J Kidney Dis. 2000 Nov;36(5):934-44. doi: 10.1053/ajkd.2000.19086.
In contrast to proteins and lipids, oxidative damage to DNA has not been well studied in patients undergoing hemodialysis (HD). We hypothesized that phagocytes are activated after blood-membrane contact during HD, and oxidants from metabolic activation can damage leukocyte DNA. To test this hypothesis, the 8-hydroxy-2'-deoxyguanosine (8-OHdG) content of leukocyte DNA was measured by high-performance liquid chromatography electrochemical detection method in 35 age- and sex-matched healthy subjects, 22 undialyzed patients with advanced renal failure, and 109 HD patients to assess the relation between oxidative DNA damage and complement-activating membranes, blood antioxidants, and iron status. Dialysis membranes were classified into complement-activating (cellulose; n = 55) and non-complement-activating (polymethylmethacrylate [PMMA]; n = 35; polysulfone [PS]; n = 19) membranes. We found increased oxidative stress in undialyzed and HD patients based on a decrease in plasma levels of ascorbate and alpha-tocopherol adjusted for blood lipid (alpha-tocopherol/lipid), serum albumin, and reduced glutathione levels in whole blood and an increase in oxidized glutathione levels in whole blood compared with controls (P < 0.001). The greatest 8-OHdG level in leukocyte DNA was in HD patients, followed by undialyzed patients and healthy controls (P < 0.001), and was significantly greater in HD patients using cellulose membranes than those using PMMA or PS membranes (P < 0.001). 8-OHdG levels correlated with plasma alpha-tocopherol/lipid (r = -0.314; P < 0.005), serum iron (r = 0. 446; P < 0.001), and transferrin saturation values (r = 0.202; P < 0.05) in the analysis of all HD patients. In a 6-week crossover study, 8-OHdG levels significantly decreased after the switch from cellulose to synthetic membranes for 2 weeks and increased after the shift from synthetic to cellulose membranes (P < 0.05). Iron metabolism indices and plasma alpha-tocopherol/lipid values did not change significantly in the study period. We conclude that 8-OHdG content in leukocyte DNA is a biomarker of oxidant-induced DNA damage in HD patients. Oxidative DNA damage is a consequence of uremia, further augmented by complement-activating membranes.
与蛋白质和脂质不同，血液透析（HD）患者的DNA氧化损伤尚未得到充分研究。我们推测，HD过程中血液与透析膜接触后吞噬细胞被激活，代谢活化产生的氧化剂会损伤白细胞DNA。为验证这一假设，采用高效液相色谱电化学检测法测定了35名年龄和性别匹配的健康受试者、22名未透析的晚期肾衰竭患者以及109名HD患者白细胞DNA中的8-羟基-2'-脱氧鸟苷（8-OHdG）含量，以评估DNA氧化损伤与补体激活膜、血液抗氧化剂及铁状态之间的关系。透析膜分为补体激活膜（纤维素膜；n = 55）和非补体激活膜（聚甲基丙烯酸甲酯[PMMA]膜；n = 35；聚砜[PS]膜；n = 19）。我们发现，与对照组相比，未透析患者和HD患者的氧化应激增加，表现为调整血脂后的血浆抗坏血酸和α-生育酚（α-生育酚/脂质）水平降低、血清白蛋白降低、全血还原型谷胱甘肽水平降低以及全血氧化型谷胱甘肽水平升高（P < 0.001）。白细胞DNA中8-OHdG水平最高的是HD患者，其次是未透析患者和健康对照（P < 0.001），且使用纤维素膜的HD患者的8-OHdG水平显著高于使用PMMA或PS膜的患者（P < 0.001）。在所有HD患者的分析中，8-OHdG水平与血浆α-生育酚/脂质（r = -0.314；P < 0.005）、血清铁（r = 0.446；P < 0.001）及转铁蛋白饱和度值（r = 0.202；P < 0.05）相关。在一项为期6周的交叉研究中，从纤维素膜转换为合成膜2周后，8-OHdG水平显著降低，从合成膜转换为纤维素膜后则升高（P < 0.05）。在研究期间，铁代谢指标和血浆α-生育酚/脂质值无显著变化。我们得出结论，白细胞DNA中的8-OHdG含量是HD患者氧化应激诱导DNA损伤的生物标志物。DNA氧化损伤是尿毒症的结果，补体激活膜会进一步加剧这种损伤。
