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 hemodialysis (HD) patients. In this study, we focused on the determinants of the 8-OHdG level in leukocyte DNA of HD patients. We further investigated the influence of vitamin E-modified, regenerated cellulose (CL-E) membrane on the oxidative DNA damage, intracellular reactive oxygen species (ROS) production of granulocytes, and plasma alpha-tocopherol concentration.


METHODS
8-OHdG content in cellular DNA of leukocytes was measured by a high-performance liquid chromatography-electrochemical detection (HPLC-ECD) method. Intracellular production of ROS, H2O2 and O2-. were analyzed by flow cytometry in leukocytes with and without phorbol-12-myristate-13-acetate (PMA) stimulation before dialysis, as well as at 15 and 30 minutes of dialysis. Plasma alpha-tocopherol concentration was measured by a HPLC method, and the value of alpha-tocopherol was corrected by total blood lipid concentration.


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, polymethylmethacrylate (PMMA), and 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-tocopherol, but correlated positively with serum iron and percentage of transferrin saturation. Forward stepwise multiple regression showed that dialysis membrane type, serum iron, and blood lipid-adjusted plasma alpha-tocopherol were the independent determinants of the leukocyte 8-OHdG level in HD patients. Like synthetic membranes, granulocyte ROS production was less augmented during dialysis with the CL-E membrane as compared with the cellulose membrane. Exposure to cellulose membrane impaired intracellular ROS production of granulocytes in response to PMA challenge, whereas the CL-E and synthetic membranes improved the granulocyte responsiveness to PMA. In the longitudinal cross-over study, the 8-OHdG level significantly decreased, and blood lipid-adjusted plasma alpha-tocopherol increased after switching the cellulose membrane to CL-E or synthetic membrane for eight weeks. In contrast, the 8-OHdG level dramatically rose, and blood lipid-adjusted plasma alpha-tocopherol declined after shift of CL-E or synthetic membrane to the cellulose membrane.


CONCLUSIONS
CL-E membrane exhibited biocompatible and bioactive characteristics. 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. Reduced DNA damage and improved immune function of leukocytes may reduce the cancer and infection risks in chronic HD patients.
Tarng
D C
DC
Institute of Clinical Medicine, Department of Biochemistry and Center for Cellular and Molecular Biology, National Yang-Ming University, Taipei, Taiwan.
Huang
T P
TP
Liu
T Y
TY
Chen
H W
HW
Sung
Y J
YJ
Wei
Y H
YH
D000080242:8-Hydroxy-2'-Deoxyguanosine; D000328:Adult; D000368:Aged; D001205:Ascorbic Acid / Q000097:blood; D001672:Biocompatible Materials / Q000627:therapeutic use; D001843:Bone Cements / Q000627:therapeutic use; D002482:Cellulose / Q000627:therapeutic use; D002851:Chromatography, High Pressure Liquid; D018592:Cross-Over Studies; D004247:DNA / Q000032:analysis; D003849:Deoxyguanosine / Q000031:analogs & derivatives* / Q000032:analysis; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D007676:Kidney Failure, Chronic / Q000628:therapy*; D007962:Leukocytes / Q000737:chemistry* / Q000378:metabolism; D008297:Male; D008567:Membranes, Artificial; D008875:Middle Aged; D018384:Oxidative Stress / Q000187:drug effects; D011108:Polymers / Q000627:therapeutic use; D019904:Polymethyl Methacrylate / Q000627:therapeutic use; D011446:Prospective Studies; D006435:Renal Dialysis / Q000295:instrumentation*; D013450:Sulfones / Q000627:therapeutic use; D014810:Vitamin E / Q000097:blood / Q000627:therapeutic use*
D001672:Biocompatible Materials; D001843:Bone Cements; D008567:Membranes, Artificial; D011108:Polymers; D013450:Sulfones; D014810:Vitamin E; C017662:polysulfone P 1700; D000080242:8-Hydroxy-2'-Deoxyguanosine; D002482:Cellulose; D004247:DNA; D019904:Polymethyl Methacrylate; D006861:Hydrogen Peroxide; D003849:Deoxyguanosine; D001205:Ascorbic Acid