Effect of vitamin E-bonded membrane on the 8-hydroxy 2 '-deoxyguanosine level in leukocyte DNA of hemodialysis patients

Background. 8-Hydroxy 2'-deoxyguanosine (8-OHdG) of leukocyte DNA has been identified as a surrogate marker of oxidative stress in chronic hemodialysi s (HD) patients. In this study, we focused on the determinants of the 8-OHd G level in leukocyte DNA of HD patients. We further investigated the influe nce of vitamin E-modified, regenerated cellulose (CL-E) membrane on the oxi dative DNA damage, intracellular reactive oxygen species (ROS) production o f granulocytes, and plasma alpha-tocopherol concentration. Methods. 8-OHdG content in cellular DNA of leukocytes was measured by a hig h-performance Liquid chromatography-electrochemical detection (HPLC-ECD) me thod. Intracellular production of ROS, H2O2 and O-2(-.) were analyzed by Ro w cytometry in leukocytes with and without phorbol 12-myristate-13-acetate (PMA) stimulation before dialysis, as well as at 15 and 30 minutes of dialy sis. Plasma alpha-tocopherol concentration was measured by a HPLC method, a nd the value of alpha-tocopherol was corrected by total blood lipid concent ration. Results. In the prospective cross sectional study, the mean 8-OHdG level in leukocyte DNA was equally lower in the patients of the CL-E, polymethylmet hacrylate (PMMA),nd polysulfone (PS) groups as compared with the cellulosic group (ANOVA, P < 0.001). The leukocyte 8-OHdG level correlated negatively with plasma alpha-tocopherol and blood lipid-adjusted plasma alpha-tocophe rol, but correlated positively with serum iron and percentage of transferri n saturation. Forward stepwise multiple regression showed that dialysis mem brane type, serum iron, and blood lipid-adjusted plasma alpha-tocopherol we re the independent determinants of the leukocyte 8-OHdG level in HD patient s. Like synthetic membranes, granulocyte ROS production was less augmented during dialysis with the CL-E membrane as compared with the cellulose membr ane. Exposure to cellulose membrane impaired intracellular ROS production o f granulocytes in response to PMA challenge, whereas the CL-E and synthetic membranes improved the granulocyte responsiveness to PMA. In the longitudi nal cross-over study, the 8-OHdG level significantly decreased, and blood l ipid-adjusted plasma alpha-tocopherol increased after switching the cellulo se membrane to CL-E or synthetic membrane for eight weeks. In contrast, the 8-OHdG level dramatically rose, and blood lipid-adjusted plasma alpha-toco pherol declined after shift of CL-E or synthetic membrane to the cellulose membrane, Conclusions. CL-E membrane exhibited biocompatible and bioactive characteri stics. Like synthetic membranes, treatment with a CL-E dialyzer effectively reduced the 8-OHdG content in leukocyte DNA. suppressed intracellular ROS production of granulocytes, and preserved the plasma level of vitamin E. It could further improve granulocyte responsiveness to a PMA challenge. Reduc ed DNA damage and improved immune function of leukocytes may reduce the can cer and infection risks in chronic I-ID patients.