Protein oxidation in chronic kidney disease.

An imbalance between oxidative processes and antioxidant systems has been widely demonstrated in chronic kidney diseases (CKD). In this study we enrolled 26 healthy subjects, 27 patients with CKD on conservative treatment (CT-CKD) with various degrees of renal failure, and 31 CKD subjects in haemodialysis treatment (HD-CKD), evaluated before and after a standard haemodialysis session. In each group we measured protein carbonyl groups (PC) as an index of protein oxidation, lipid peroxidation (TBARS) and two plasma markers of leukocyte activation, elastase and myeloperoxidase (MPO). In CT-CKD subjects the PC level was significantly higher than in normal controls, and it was negatively correlated with creatinine clearance. In HD-CKD patients the PC concentration was significantly increased also in comparison with CT-CKD. An increase in TBARS was present both in CT-CKD and in HD-CKD patients, but in HD-CKD patients TBARS were lower than in CT-CKD. Elastase was increased in both CKD groups, while MPO was not different among control and patient groups. In HD-CKD patients the HD session was followed by a further increase in PC, as well as by an increase in elastase and MPO, whereas TBARS did not change. Protein oxidation accelerates the glycation processes and seems to be connected with the chronic inflammatory state detectable in renal failure, although we did not observe any significant correlation between PC level and leukocyte activation markers.