The removal of serum hepcidin by different dialysis membranes

The Characteristics of Dialysis Membranes: Benefits of the AN69 Membrane in Hemodialysis Patients

Patients undergoing hemodialysis (HD) experience serious cardiovascular complications, through malnutrition, inflammation, and atherosclerosis. Amputation for peripheral arterial disease (PAD) is more prevalent in patients undergoing HD than in the general population. In addition, revascularization procedures in dialysis patients are often associated with subsequent amputation and high mortality rates. To improve the prognosis of dialysis patients, malnutrition and inflammation must be properly treated, which necessitates a better understanding of the characteristics of dialysis membranes. Herein, the characteristics of several dialysis membranes were studied, with a special reference to the AN69 membrane, noting several similarities to low-density lipoprotein (LDL)-apheresis, which is also applicable for the treatment of PAD. Both systems (LDL-apheresis and AN69) have anti-inflammatory and anti-thrombogenic effects because they use a negatively charged surface for extracorporeal adsorptive filtration from the blood/plasma, and contact phase activation. The concomitant use of both these therapeutic systems may have additive therapeutic benefits in HD patients. Here, we reviewed the characteristics of dialysis membranes and benefits of the AN69 membrane in dialysis patients.

Comparison of the removal of uraemic toxins with medium cut-off and high-flux dialysers: a randomized clinical trial

BACKGROUND

Accumulation of middle-weight uraemic toxins in haemodialysis (HD) patients results in increased morbidity and mortality. Whether medium cut-off HD (MCO-HD) improves removal of middle-weight uraemic toxins remains to be demonstrated.

METHODS

This cross-over prospective study included 40 patients randomly assigned to receive either 3 months of MCO-HD followed by 3 months of high-flux HD (HF-HD), or vice versa. The primary endpoint was myoglobin reduction ratio (RR) after 3 months of MCO-HD. Secondary endpoints were the effect of MCO-HD on other middle-weight toxins and protein-bound toxins, and on parameters of nutrition, inflammation, anaemia and oxidative stress.

RESULTS

Compared with HF-HD, MCO-HD provided higher mean RR of myoglobin (36 ± 8 versus 57 ± 13%, P < 0.0001), beta2-microglobulin (68 ± 6 versus 73 ± 15%, P = 0.04), prolactin (32 ± 13 versus 59 ± 11%, P < 0.0001), fibroblast growth factor 23 (20 ± 21 versus 41 ± 22%, P = 0.0002), homocysteine (43 ± 7 versus 46 ± 9%, P = 0.03) and higher median RR of kappa [54 (48-58) versus 70 (63-74)%, P < 0.0001] and lambda free light chain (FLC) [15 (9-22) versus 44 (38-49)%, P < 0.0001]. Mean ± SD pre-dialysis levels of beta2-microglobulin (28.4 ± 5.6 versus 26.9 ± 5.1 mg/L, P = 0.01) and oxidized low-density lipoprote (6.9 ± 4.4 versus 5.5 ± 2.5 pg/mL, P = 0.04), and median (interquartile range) kappa FLC [145 (104-203) versus 129 (109-190) mg/L, P < 0.03] and lambda FLC [106 (77-132) versus 89 (62-125) mg/L, P = 0.002] were significantly lower. Mean albumin levels decreased significantly (38.2 ± 4.1 versus 36.9 ± 4.3 g/L, P = 0.004), without an effect on nutritional status as suggested by unchanged normalized protein catabolic rate and transthyretin level.

CONCLUSIONS

Compared with HF-HD, MCO-HD provides higher myoglobin and other middle molecules RR and is associated with moderate hypoalbuminemia. The potential benefits of this strategy on long-term clinical outcomes deserve further evaluation.

A hepcidin-based approach for iron therapy in hemodialysis patients: A pilot study

INTRODUCTION

Hepcidin is a key factor that regulates iron homeostasis. In hemodialysis patients (HD), a high hepcidin level may decrease intestinal iron absorption and reduce the efficacy of Oral iron vs Intravenous iron therapy. Whether the hepcidin level in HD could guide oral iron therapy is unclear.

METHODS

We report a monocentric study on nine "erythropoietin (EPO)-free" patients (without recombinant human EPO [rHU-EPO] for at least 6 months) and normal hepcidin level (<20 ng mL) during the study. After 15 days of washout, oral iron (ferrous sulfate 80 mg/day) was introduced. The primary end point was the hemoglobin response and iron store at 3 months.

FINDINGS

Nine patients (8 men, 1 woman) with a median age of 62 years (range 42-79) were included. After 1 week of treatment, the median transferrin saturation index increased from 15% (range 6-61) to 34% (range 13-42), P = 0.62, reflecting intestinal absorption. The median ferritin level remained stable 80 μg/L (35-293) vs 82 μg/L (range 37-496) between M0 and M3, P = 0.43. During the 3-month study, median hemoglobin level increased from 11.5 d/dL (range10.4-13.7) to 12.8 g/dL (range 11.1-15.2), P = 0.01. No major side effects were observed. Quality of life assessed by the SF-36 criteria was similar during the 3-month study.

DISCUSSION

Oral iron therapy is effective and safe in EPO-free patients with normal hepcidin levels. These findings suggest that serum hepcidin may be a marker for defining iron therapy strategies in HD patients. HD patients treated with rHU-EPO and with normal hepcidin levels could benefit from oral iron treatment.

A single dialysis session of hemodiafiltration with sorbent-regenerated endogenous ultrafiltrate reinfusion (HFR) removes hepcidin more efficiently than bicarbonate hemodialysis: a new approach to containing hepcidin burden in dialysis patients?

BACKGROUND

Most hemodialysis patients have high Hepcidin-25 levels, which may be involved in the pathogenesis of several uremic complications related to an altered iron biology. The hemodialysis procedure itself can influence Hepcidin-25 levels by removing Hepcidin-25 and maybe stimulating its production due to a pro-inflammatory effect.

METHODS

To assess the relationship between dialysis-related inflammation and intradialysis changes in Hepcidin-25, we performed a crossover trial in 28 hemodialysis patients to compare the effects on serum levels of Hepcidin-25 and inflammatory markers activated during dialysis [Tumor Necrosis Factor-α (TNF-α), Interleukin-6, C-reactive protein (CRP), Pentraxin-3] of a single dialysis session using a technique capable of reducing inflammation, HFR (Hemo Filtrate Reinfusion: a hemodiafiltration system combining convection, diffusion and adsorption) or bicarbonate-dialysis using either the same low-flux membrane as in the diffusion stage of HFR (LFBD) or a high-flux membrane (HFBD).

RESULTS

HFR achieved a greater reduction in Hepcidin-25 levels than both LFBD [-72% (95% CI: -11 to -133), p = 0.022] and HFBD [-137% (95% CI: -2 to -272), p = 0.047], conceivably due to both a greater removal (because of its convective/adsorptive component) and a lower inflammation-related Hepcidin-25 production. HFR also led to a greater decrease in TNF-α than LFBD [-277% (95% CI: -59 to -494), p = 0.014], while the two methods induced similar changes in Interleukin-6, CRP and Pentraxin-3 levels.

CONCLUSIONS

Our findings suggest that a single bicarbonate-dialysis session can upregulate Hepcidin-25 synthesis and that HFR can fully overcome this effect, enabling a greater Hepcidin-25 removal during dialysis. Adequately-designed studies are needed, however, to establish whether the beneficial effect of HFR emerging from our study could reduce Hepcidin-25 (and TNF-α) burden and improve clinically-relevant outcomes.

TRIAL REGISTRATION

ISRCTN15957905.

Dynamics of the erythropoiesis stimulating agent resistance index in incident hemodiafiltration and high-flux hemodialysis patients

Hyporesponsiveness to erythropoiesis-stimulating agent therapy in dialysis patients is poorly understood. Some studies report an improvement in the erythropoiesis-stimulating agent resistance index (ERI) with hemodiafiltration (HDF) versus high-flux hemodialysis (HD). We explored ERI dynamics in 38,340 incident HDF and HD patients treated in 22 countries over a 7-year period. Groups were matched by propensity score at baseline (6 months after dialysis initiation). The follow-up period (mean of 1.31 years) was stratified into 1 month intervals with delta analyses performed for key ERI-related parameters. Dialysis modality, time interval, and polycystic kidney disease were included in a linear mixed model with the outcome ERI. Baseline ERI was nonsignificantly higher in HDF versus HD treatment. ERI decreased significantly faster in HDF-treated patients than in HD-treated patients, was decreased in both HD and HDF when patients were treated with intravenous darbepoetin alfa, but only in HDF when treated with intravenous recombinant human erythropoietin (rHuEPO). A clear difference between HD- and HDF-treated patients could only be found for patients with high baseline ERI and assigned to intravenous rHuEPO treatment. A significant advantage in terms of lower ERI for patients treated by HDF was found. Sensitivity analysis limited this advantage for HDF to those patients treated with intravenous rHuEPO (not darbepoetin alfa or subcutaneous rHuEPO) and to patients with a high baseline ERI. Thus, our results allow more accurate planning for future clinical trials addressing anemia management in dialysis patients.

Hepcidin and its potential clinical utility

A number of pathophysiological conditions are related to iron metabolism disturbances. Some of them are well known, others are newly discovered or special. Hepcidin is a newly identified iron metabolism regulating hormone, which could be a promising biomarker for many disorders. In this review, we provide background information about mammalian iron metabolism, cellular iron trafficking, and the regulation of expression of hepcidin. Beside these molecular biological processes, we summarize the methods that have been used to determine blood and urine hepcidin levels and present those pathological conditions (cancer, inflammation, neurological disorders) when hepcidin measurement may have clinical relevance.