Hemodiafiltration with online regeneration of ultrafiltrate: effect on heme-oxygenase-1 and inducible subunit of nitric oxide synthase and implication for oxidative stress and inflammation.

Hemodiafiltration with regeneration of ultrafiltrate (HFR) has a positive impact on inflammation and oxidative stress (OxSt), risk factors for cardiovascular disease (CVD), the most common cause of excess morbidity and mortality for end-stage renal disease (ESRD) patients. However, studies have been of limited duration. This study extends our previous study of HFR effects by evaluating the effect on mononuclear cell protein expression of heme-oxygenase-1 (HO-1), induced by OxSt, and inducible subunit of nitric oxide synthase (iNOS), and plasma level of interleukin-1β (Il-1β) and oxidized low-density lipoproteins (OxLDL), marker of OxSt, for a 12-month period. Fourteen ESRD patients stable on hemodialysis over a period of at least 2 years and on conventional bicarbonate dialysis were switched to be treated with HFR. Blood samples were collected at baseline, after 3, 6, 9 and 12 months. HO-1 and iNOS protein expression were evaluated by Western blot, OxLDL by enzyme-linked immunosorbent assay (ELISA), and Il-1β by enzyme amplified sensitivity immumoassay assay. HFR significantly increased HO-1 at the 9 and 12 months (ANOVA = P < 0.00001): 0.17 ± 0.11 (baseline) versus 0.48 ± 0.20, P < 0.043 and 0.59 ± 0.32, P < 0.004, respectively. Il-1β declined (ANOVA = P < 0.0001) since the 3 months from 169.92 ± 92.39 pg/mL (baseline) to 39.03 ± 10.01 (12 months), P < 0.0001. HFR also reduced plasma OxLDL: 475.4 ± 110.8 ng/mL (baseline) versus 393.1 ± 101.9 ng/mL (12 months), P < 0.04. iNOS showed no changes upon HFR treatment. These results together with our previous results indicate that HFR improves OxSt and inflammation. Given the strong relationships between OxSt and inflammation with CVD, their reduction might provide a beneficial impact by reducing the risk of atherosclerotic CVD in dialysis patients.