Coagulation activation is associated with nicotinamide adenine dinucleotide phosphate oxidase-dependent reactive oxygen species generation in hemodialysis patients.

AIMS: This study investigated on (i) the role of gp91(phox)/NOX2 in reactive oxygen species (ROS) generation in hemodialysis (HD) patients, and (ii) the link between clotting activation and ROS production in this setting. RESULTS: The study was performed on peripheral blood mononuclear cells (PBMCs) isolated from HD patients randomized to polysulphon/polyamide (S-group, n=30) or ethylene-vinyl-alcohol (EVAL) membrane (E-group, n=30) treatment and from healthy subjects (control group, n=15). ROS generation was increased in PBMCs of HD patients compared with healthy subjects. S-group showed higher levels of intracellular ROS generation than control, whereas E-group did not. In addition, S-group displayed an increase in nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity compared with E-group and healthy subjects. A further increase in NADPH activity shortly after HD treatment was observed only in S-group. The plasma levels of the prothrombin fragment F1+2, a marker of in vivo clotting activation, were significantly higher in S-group than in E-group. Moreover, a heightened thrombin generation was recorded in the plasma of S-group. Intracellular ROS production correlated with NADPH oxidase activity and coagulation priming in HD patients. The in vitro validation study demonstrated that incubation of PBMCs with activated FX induced a significant increase in intracellular ROS production, superoxide generation, and gp91(phox)/NOX2 expression. INNOVATION: The pivotal role of NADPH oxidase in the upregulation of ROS in HD patients makes this enzyme a potential target for therapeutic intervention in the treatment of HD-related oxidative stress. CONCLUSION: The EVAL membrane, by reducing clotting activation, inhibits gp91(phox)/NOX2-related ROS production in HD patients.

Early markers of tubular dysfunction in antiretroviral-experienced HIV-infected patients treated with tenofovir versus abacavir.

Tenofovir disoproxil fumerate (TDF) is an effective nucleoside reverse transcriptase inhibitor for HIV infection but it is potentially nephrotoxic. A selective mithochondrial toxicity has been hypothesized. To assess early markers of renal toxicity, we evaluated a cohort of antiretroviral (ARV)-experienced HIV patients who had been switched from a thymidinic backbone to either a TDF/emtricitabine regimen (TDF; 73 patients) or an abacavir/lamivudine (ABV) regimen (28 patients). Markers of mitochondrial toxicity (cytochrome c, Cyc) or cytosolic (α-glutathione S transferase, α-GST) together with common indicators of renal damage were assessed at baseline (T0) and after 1 (T1), 3 (T2), 6 (T3), and 12 (T4) months of patient exposure to therapy. Clinical features of both groups were comparable at T0. There was no significant variation in estimated glomerular filtration rate (eGRF), median urine protein excretion, or microalbuminuria and serum phosphate levels in both groups during the study period. There was a significant increase in urinary excretion of phosphate in patients on TDF compared to those on ABV at T3 and T4. Fractional excretion of uric acid was also altered in the two treatment groups; there was no change in the ABV (constantly less than 0.10), but a progressive increase in TDF patients. Serum potassium levels were significantly lower in ABV than in TDF treated patients. Urine concentrations of α-GST showed a nonsignificant variation in both groups, while Cyc excretion was significantly higher at T1 and T3 in TDF-treated compared to ABV-treated patients. In conclusion, TDF may be associated with subclinical mitochondrial damage, inducing at a later stage increased urinary excretion of phosphate and uric acid, as markers of incipient tubular injury.