Oxidative stress effects fibrinolytic system in dialysis uraemic patients

Enhanced oxidative stress (SOX) and changes in the fibrinolytic system are common in end-stage renal failure patients undergoing maintenance dialysis. This study attempted to verify the existence of a relationship between SOX documented by Cu/Zn superoxide dismutase (Cu/Zn SOD) and fibrinolysis analyzed by tissue-type plasminogen activator (tPA), urokinase-type plasminogen activator (uPA), plasminogen activator inhibitor 1 (PAI-1) and plasmin/antiplasmin (PAP) complexes in dialysis patients.

Twenty-seven patients on maintenance haemodialysis (HD) and 16 on maintenance peritoneal dialysis (CAPD) were examined together with 18 healthy controls. Pre-dialysis blood levels of all the parameters were determined using commercially ELISA kits.

Cu/Zn SOD, uPA and PAP levels were increased in both groups of dialyzed patients compared to the controls. PAI-1 was significantly lower in CAPD subjects compared to HD subjects and control group. PAI-1/uPA ratio and PAI-1/tPA ratio were significantly decreased in CAPD and HD compared to controls, being significantly lower in CAPD patients relative to HD patients. In the patients, increased Cu/Zn SOD levels directly correlated with those of uPA (r=0.565, p<0.0001) and PAP (r=0.335, p<0.05); the fibrinolytic markers were also positively associated with each other (r=0.377, p<0.05).

The positive association between Cu/Zn SOD and both uPA as well as PAP levels suggests a link between SOX and the fibrinolytic activity in dialysis patients. We hypothesize that increased SOX-mediated fibrinolytic activity may be a part of the counter-system against activation of blood coagulation in these patients.