Biocompatibility of heparin-grafted hemodialysis membranes: Impact on monocyte chemoattractant protein-1 circulating level and oxidative status

What is the role of the neutrophil extracellular traps in the cardiovascular disease burden associated with hemodialysis bioincompatibility?

Despite significant progress in dialysis modalities, intermittent renal replacement therapy remains an "unphysiological" treatment that imperfectly corrects uremic disorders and may lead to low-grade chronic inflammation, neutrophil activation, and oxidative stress due to repetitive blood/membrane interactions contributing to the "remaining uremic syndrome" and cardiovascular disease burden of hemodialysis patients. Understanding dialysis bioincompatibility pathways still remains a clinical and biochemical challenge. Indeed, surrogate biomarkers of inflammation including C-reactive protein could not discriminate between all components involved in these complex pathways. A few examples may serve to illustrate the case. Cytokine release during dialysis sessions may be underestimated due to their removal using high-flux dialysis or hemodiafiltration modalities. Complement activation is recognized as a key event of bioincompatibility. However, it appears as an early and transient event with anaphylatoxin level normalization at the end of the dialysis session. Complement activation is generally assumed to trigger leukocyte stimulation leading to proinflammatory mediators' secretion and oxidative burst. In addition to being part of the innate immune response involved in eliminating physically and enzymatically microbes, the formation of Neutrophil Extracellular Traps (NETs), known as NETosis, has been recently identified as a major harmful component in a wide range of pathologies associated with inflammatory processes. NETs result from the neutrophil degranulation induced by reactive oxygen species overproduction via NADPH oxidase and consist of modified chromatin decorated with serine proteases, elastase, bactericidal proteins, and myeloperoxidase (MPO) that produces hypochlorite anion. Currently, NETosis remains poorly investigated as a sensitive and integrated marker of bioincompatibility in dialysis. Only scarce data could be found in the literature. Oxidative burst and NADPH oxidase activation are well-known events in the bioincompatibility phenomenon. NET byproducts such as elastase, MPO, and circulating DNA have been reported to be increased in dialysis patients more specifically during dialysis sessions, and were identified as predictors of poor outcomes. As NETs and MPO could be taken up by endothelium, NETs could be considered as a vascular memory of intermittent bioincompatibility phenomenon. In this working hypothesis article, we summarized the puzzle pieces showing the involvement of NET formation during hemodialysis and postulated that NETosis may act as a disease modifier and may contribute to the comorbid burden associated with dialysis bioincompatibility.

A multicenter study of the clinical, laboratory characteristics, and potential prognostic factors in patients with amyloid A amyloidosis on hemodialysis

INTRODUCTION

While light chain (AL) amyloidosis is more common in western countries, the most common type of amyloidosis is amyloid A (AA) amyloidosis in Eastern Mediterranean Region, including Turkey. Although worse prognosis has been attributed to the AL amyloidosis, AA amyloidosis can be related to higher mortality under renal replacement therapies. However, there are no sufficient data regarding etiology, clinical presentation, and prognostic factors of AA amyloidosis. The objective of our study is to evaluate the clinical, laboratory characteristics, and possible predictive factors related to mortality in patients with AA amyloidosis undergoing hemodialysis (HD).

METHODS

This multicenter, cross-sectional study was a retrospective analysis of 2100 patients on HD. It was carried out in 14 selected HD centers throughout Turkey. Thirty-two patients with biopsy-proven AA amyloidosis and thirty-two control patients without AA amyloidosis undergoing HD were included between October 2018 and October 2019. There was no significant difference between the groups in terms of age and dialysis vintage. Causes of AA amyloidosis, treatment (colchicine and/or anti-interleukin 1 [IL] treatment), and the number of familial Mediterranean fever (FMF) attacks in the last year in case of FMF, systolic and diastolic blood pressures, biochemical values such as mean CRP, hemoglobin, serum albumin, phosphorus, calcium, PTH, ferritin, transferrin saturation, total cholesterol levels, EPO dose, erythropoietin-stimulating agents resistance index, interdialytic fluid intake, body mass indexes, heparin dosage, UF volume, and Kt/V data in the last year were collected by retrospective review of medical records.

FINDINGS

Prevalence of AA amyloidosis was found to be 1.87% in HD centers. In amyloidosis and control groups, 56% and 53% were male, mean age was 54 ± 11 and 53 ± 11 years, and mean dialysis vintage was 104 ± 94 and 107 ± 95 months, respectively. FMF was the most common cause of AA amyloidosis (59.5%). All FMF patients received colchicine and the mean colchicine dose was 0.70 ± 0.30 mg/day. 26.3% of FMF patients were unresponsive to colchicine and anti-IL-1 treatment was used in these patients. In AA amyloid and control groups, erythropoietin-stimulating agents resistance index were 7.88 ± 3.78 and 5.41 ± 3.06 IU/kg/week/g/dl, respectively (p = 0.008). Additionally, higher CRP values (18.78 ± 18.74 and 10.61 ± 10.47 mg/L, p = 0.037), lower phosphorus (4.68 ± 0.73 vs. 5.25 ± 1.04 mg/dl, p = 0.014), total cholesterol (135 ± 42 vs. 174 ± 39 mg/dl, p < 0.01), and serum albumin (3.67 ± 0.49 mg/dl, 4.03 ± 0.22, p < 0.01) were observed in patients with AA amyloidosis compared to the control group.

DISCUSSION

In this study, we found that long-term prognostic factors including higher inflammation, malnutritional parameters, and higher erythropoietin-stimulating agents resistance index were more frequent in AA amyloidosis patients under HD treatment.

Hemodiálisis extendida frente a convencional o hemodiafiltración en línea. Estudio comparativo de necesidad de heparina y coagulación del sistema

Introducción: La reciente aparición de membranas de corte medio ofrece una alternativa para la eliminación de moléculas medianas y nueva terapia dialítica, la hemodiálisis expandida. Estas membranas se caracterizan por un mayor tamaño de poro que podría afectar a la eliminación de la heparina utilizada durante las sesiones de hemodiálisis. Objetivo: Determinar si existen diferencias en la necesidad de heparina y el estado de coagulación del sistema y dializador según técnica dialítica empleada. Material y Método: Estudio cuasiexperimental en pacientes en hemodiálisis con dos periodos de estudio, en el primero, el paciente realizó hemodiálisis convencional o hemodiafiltración y en el segundo, hemodiálisis expandida con membranas de corte medio. Resultados: El dializador quedó parcialmente coagulado en el 10,3% de las sesiones de hemodiálisis expandida frente al 19,1% de las sesiones de hemodiálisis y el 11,4% de hemodiafiltración (p=0,011). Conclusiones: La hemodiálisis expandida ofrece mejor estado de coagulación final del sistema y dializador que otras membranas.

Dialyzer Performance During Hemodialysis Without Systemic Anticoagulation Using a Heparin-Grafted Dialyzer Combined With a Citrate-Enriched Dialysate: Results of the Randomized Crossover Noninferiority EvoCit Study

RATIONALE & OBJECTIVE

The EvoCit study was designed to evaluate performance of a heparin-grafted dialyzer during hemodialysis with and without systemic anticoagulation.

STUDY DESIGN

Randomized, crossover, noninferiority trial. Noninferiority was defined as a difference of≤10% for the primary outcome.

SETTING & PARTICIPANTS

Single hemodialysis center; 26 prevalent patients treated with 617 hemodialysis sessions.

INTERVENTIONS

Hemodialysis using a heparin-grafted dialyzer combined with a 1.0mmol/L citrate-enriched dialysate ("EvoCit") without systemic anticoagulation compared with hemodialysis performed with a heparin-grafted dialyzer with systemic heparin ("EvoHep"). Patients were randomly allocated to a first period of 4 weeks and crossed over to the alternative strategy for a second period of 4 weeks.

OUTCOMES

The primary end point was the difference in Kt/V_urea between EvoCit and EvoHep. Secondary end points were urea reduction ratio, middle molecule removal, treatment time, thrombin generation, and reduction in dialyzer blood compartment volume.

RESULTS

The estimated difference in Kt/V_urea between EvoCit and EvoHep was-0.03 (95% CI, -0.06 to-0.007), establishing noninferiority with mean Kt/V_urea of 1.47±0.05 (SE) for EvoCit and 1.50±0.05 for EvoHep. Noninferiority was also established for reduction ratios of urea and β₂-microglobulin. Premature discontinuation of dialysis was required for 4.2% of sessions among 6 patients during EvoCit and no sessions during EvoHep. Effective treatment time was 236±5 minutes for EvoCit and 238±1 minutes for EvoHep. Thrombin generation was increased and there was greater reduction in dialyzer blood compartment volume after treatments with EvoCit compared with EvoHep.

LIMITATIONS

The effects of avoiding systemic anticoagulation on clinical outcomes were not evaluated.

CONCLUSIONS

EvoCit is noninferior to EvoHep with respect to solute clearance but results in a greater number of shortened treatments, more membrane clotting, and greater thrombin generation TRIAL REGISTRATION: Registered at ClinicalTrials.gov with study number NCT03887468.

Reconsidering adsorption in hemodialysis: is it just an epiphenomenon? A narrative review

Since the first attempt at extracorporeal renal replacement therapy, renal replacement therapy has been constantly improved. In the field of hemodialysis, substantial efforts have been made to improve toxin removal and biocompatibility. The advent of hemodiafiltration (HDF) and, more recently, of mid cut-off membranes have contributed to management of patients with end-stage renal disease (ESRD). Although several uremic toxins have been discovered, we know little about the clinical impact of their clearance in hemodialysis patients. In addition, a great deal of progress has been made in the areas of filtration and diffusion, but the adsorptive properties of hemodialysis membranes remain under-studied. The mechanism of action of adsorption is based on the attraction between the polymer of the dialysis membrane and the solutes, through hydrophobic interactions, ionic or electrostatic forces, hydrogen bonds or van der Waals forces. Adsorption on the dialysis membrane depends on the membrane surface, pore size, structure and electric load. Its involvement in toxin removal and biocompatibility is significant, and is not just an epiphenomenon. Diffusive and convective properties cannot be improved indefinitely and high permeability membranes, despite their high performance in the clearance of many toxins, have several limitations for long-term use in hemodialysis. This review will discuss why adsorption should be reconsidered and better characterized to improve efficiency and adequacy of dialysis.

Anticoagulation in hemodialysis: A narrative review

Systemic anticoagulation in maintenance hemodialysis (HD) has historically been considered necessary to maintain the extracorporeal circuit (ECC) and preserve dialysis efficiency. Unfractionated heparin (UFH) is the most commonly used anticoagulant due to low cost and staff familiarity. Despite widespread use, there is little standardization of heparin dosing protocols in the United States. Although the complication rates with UFH are low for the general population, certain contraindications have led to exploration in alternative anticoagulants in patients with end-stage kidney disease (ESKD). Here we review the current evidence regarding heparin dosing protocols, complications associated with heparin use, and discuss alternatives to UFH including anticoagulant-free routine HD.

Arteriovenous access in hemodialysis: A multidisciplinary perspective for future solutions

In hemodialysis, vascular access is a key issue. The preferred access is an arteriovenous fistula on the non-dominant lower arm. If the natural vessels are insufficient for such access, the insertion of a synthetic vascular graft between artery and vein is an option to construct an arteriovenous shunt for punctures. In emergency situations and especially in elderly with narrow and atherosclerotic vessels, a cuffed double-lumen catheter is placed in a larger vein for chronic use. The latter option constitutes a greater risk for infections while arteriovenous fistula and arteriovenous shunt can fail due to stenosis, thrombosis, or infections. This review will recapitulate the vast and interdisciplinary scenario that characterizes hemodialysis vascular access creation and function, since adequate access management must be based on knowledge of the state of the art and on future perspectives. We also discuss recent developments to improve arteriovenous fistula creation and patency, the blood compatibility of arteriovenous shunt, needs to avoid infections, and potential development of tissue engineering applications in hemodialysis vascular access. The ultimate goal is to spread more knowledge in a critical area of medicine that is importantly affecting medical costs of renal replacement therapies and patients’ quality of life.

Randomised trial on clinical performances and biocompatibility of four high-flux hemodialyzers in two mode treatments: hemodialysis vs post dilution hemodiafiltration

This prospective multicenter randomized comparative cross-over trial aimed at evaluating the influence of hemodialysis vs post-dilution hemodiafiltration with high-flux dialyzers in solute clearance and biocompatibility profile. 32 patients were sequentially dialyzed with Leoceed-21HX, Polypure-22S+, Rexsys-27H and VIE-21A. Primary outcome was β2-microglobulin removal. Secondary outcomes were (i) extraction of other uremic solutes (ii) parameters of inflammation and nutrition and (iii) comparative quantification of perdialytic albumin losses (using total ‘TDC’ vs partial ‘PDC’ collection of dialysate). Significant increases in removal rates of β2-microglobulin (84.7 ± 0.8 vs 71.6 ± 0.8 mg/L), myoglobin (65.9 ± 1.3 vs 38.6 ± 1.3 µg/L), free immunoglobulin light chains Kappa (74.9 ± 0.8 vs 55.6 ± 0.8 mg/L), β-trace protein (54.8 ± 1.3 vs 26.8 ± 1.4 mg/L) and orosomucoid (11.0 ± 1.1 vs 6.0 ± 1.1 g/L) but not myostatin (14.8 ± 1.5 vs 13.0 ± 1.5 ng/mL) were observed in HDF compared to HD when pooling all dialyzers. Rexsys and VIE-A use in both HD and HDF subgroups was associated to a better removal of middle/large-size molecules compared to Leoceed and Polypure, except β2-microglobulin for Rexsys. Inflammatory parameters were unchanged between dialyzers without any interaction with dialysis modality. Mean dialysate albumin loss was comparable between TDC and PDC (1.855 vs 1.826 g/session for TDC and PDC respectively). In addition, a significant difference in albumin loss was observed between dialyzers with the highest value (4.5 g/session) observed using Rexsys. Use of all dialyzers was associated with good removals of the large spectrum of uremic toxins tested and good biocompatibility profiles, with an additional gain in removal performances with HDF. Larger surface area, thinner wall and resultant very high ultrafiltration coefficient of Rexsys should be taken into account in its clear performance advantages.

Unexpected and striking effect of heparin-free dialysis on cytokine release

Heparin (both unfractionated and low molecular weight) is not only a potent anticoagulant but also has many pleiotropic effects, some of which are mediated by cytokine release. We compared the effect of hemodialysis (HD) with enoxaparin as an anticoagulant and without systemic anticoagulation (heparin-grafted membrane—Evodial) on the release of monocyte chemoattractant protein 1 (MCP-1), endostatin (ES) and activin A (Act-A). Nineteen stable HD patients were dialyzed with or without heparin, and plasma levels of MCP-1, ES and Act-A were measured after such a dialysis. During HD with Evodial, the intradialytic levels of all three cytokines were 2–3 folds lower. The between-anticoagulant differences were significant over time for all three cytokines: MCP-1 (P < 0.001), ES (P < 0.001) and Act-A (P < 0.001). This striking effect of heparin-free dialysis with Evodial membrane may be beneficial not only because it reduces the possibility of bleeding complications but also because it might reduce proinflammatory cytokine concentration and therefore contribute to the improvement in endothelial function. Further studies are needed to determine whether it has a positive effect on morbidity and mortality of maintenance HD patients.

Modified Lipids and Lipoproteins in Chronic Kidney Disease: A New Class of Uremic Toxins

Chronic kidney disease (CKD) is associated with an enhanced oxidative stress and deep modifications in lipid and lipoprotein metabolism. First, many oxidized lipids accumulate in CKD and were shown to exert toxic effects on cells and tissues. These lipids are known to interfere with many cell functions and to be pro-apoptotic and pro-inflammatory, especially in the cardiovascular system. Some, like F2-isoprostanes, are directly correlated with CKD progression. Their accumulation, added to their noxious effects, rendered their nomination as uremic toxins credible. Similarly, lipoproteins are deeply altered by CKD modifications, either in their metabolism or composition. These impairments lead to impaired effects of HDL on their normal effectors and may strongly participate in accelerated atherosclerosis and failure of statins in end-stage renal disease patients. This review describes the impact of oxidized lipids and other modifications in the natural history of CKD and its complications. Moreover, this review focuses on the modifications of lipoproteins and their impact on the emergence of cardiovascular diseases in CKD as well as the appropriateness of considering them as actual mediators of uremic toxicity.

Vitamin E-Coated and Heparin-Coated Dialyzer Membranes for Heparin-Free Hemodialysis: A Multicenter, Randomized, Crossover Trial

BACKGROUND

Hemodialysis requires effective anticoagulation to avoid blood circuit clotting. In patients at high risk for bleeding, several alternative methods have been developed.

STUDY DESIGN

Multicenter, prospective, randomized, crossover study evaluating the noninferiority of vitamin E-coated compared with heparin-coated dialyzers in a 4-hour heparin-free hemodialysis strategy.

SETTINGS & PARTICIPANTS

32 adult long-term hemodialysis patients from 2 French hemodialysis units with well-functioning fistulas or double-lumen catheters.

INTERVENTION

Patients were randomly allocated to a first period using either vitamin E- or heparin-coated dialyzers. After a washout period of 2 hemodialysis sessions, each patient was switched to the alternative dialyzer for a second period. Each study period started with 2 hemodialysis sessions with reduced heparin dose (50% and 25% of usual heparin dose, respectively, for sessions 1 and 2) followed by 2 heparin-free sessions.

OUTCOMES

The primary end point was the percentage of successful study periods, defined as no circuit-clotting event leading to premature interruption of any of the 4 dialysis sessions. Secondary end points included total number and cumulative duration of hemodialysis sessions without clotting, number of saline solution flushes, dialysis circuit bubble trap status and dialyzer membrane status by visual inspection, and dialysis adequacy.

RESULTS

The percentage of success with vitamin E-coated dialyzers (25/32 study periods [78%]) was not inferior to that with heparin-coated dialyzers (26/32 study periods [81%]). Visual inspection showed equal numbers of clean dialysis circuit bubble traps (vitamin E-coated, 34/121; heparin-coated, 32/120), whereas clean fiber bundles were more frequently noted with the vitamin E-coated compared with heparin-coated dialyzers (25/121 vs 2/120; P=0.002).

LIMITATIONS

Results may not extrapolate to critically ill patients. Differences in dialyzer transparency may account for visual inspection scores.

CONCLUSIONS

The success rate of 4-hour heparin-free hemodialysis sessions is lower than that previously claimed in uncontrolled studies. Vitamin E-coated and heparin-coated dialyzers exposed patients to similar and unacceptable high failure rates. Further studies are required to improve heparin-free hemodialysis.

Preparation and characterization of a thrombin inhibitor grafted polyethersulfone blending membrane with improved antithrombotic property

A thrombin inhibitor grafted polyethersulfone membrane with improved antithrombotic property.

Monocyte chemoattractant protein-1 gene (MCP-1-2518 A/G) polymorphism and serological markers of hepatitis B virus infection in hemodialysis patients

Background

The role of MCP1-2518 A/G in hepatitis B virus (HBV) infection is controversial. Our aim was to evaluate the frequency distribution of MCP1-2518 A/G (rs1024611) polymorphic variants in hemodialysis (HD) patients without or with type 2 diabetes in relation to serological markers of HBV infection.

Material/Methods

HD patients (n=170, 48 with diagnosis of type 2 diabetes), who tested positive for total antibodies to HBV core antigen (anti-HBc), underwent MCP1 genotyping using polymerase chain reaction-restriction fragment length polymorphism assay. Anti-HBc was accompanied by antibodies to HBV surface antigen (anti-HBs) in 127 individuals. In anti-HBc-positive/anti-HBs-negative patients, HBV surface antigen (HBsAg) was shown in 15 patients and isolated anti-HBc were present in 28 patients. The distribution of MCP1 genotypes in anti-HBc-positive patients was compared to that in healthy subjects (n=437) and anti-HBc-negative HD patients (n=754).

Results

There were no significant differences (P_trend >0.05) in distribution of MCP1 genotypes between anti-HBc-positive patients, anti-HBc-negative subjects, and controls, regardless of anti-HBs or diabetic status. The MCP1-2518G allele prevalence was higher in HBsAg-positive/anti-HBs-negative patients defined as HBV carriers compared to MCP1-2518G allele frequency shown in groups composed of HBsAg-negative HD individuals and controls (50% vs. 28%, P_trend 0.022).

Conclusions

A frequency distribution of MCP1 polymorphic variants is not associated with anti-HBs development in response to HBV infection in HD patients, independent of diabetic status, but the MCP1-2518G allele may predispose to HBsAg persistence (HBV carrier status).

Rationale and design of the HepZero study: a prospective, multicenter, international, open, randomized, controlled clinical study with parallel groups comparing heparin-free dialysis with heparin-coated dialysis membrane (Evodial) versus standard care: study protocol for a randomized controlled trial

Background

Anticoagulation for chronic dialysis patients with contraindications to heparin administration is challenging. Current guidelines state that in patients with increased bleeding risks, strategies that can induce systemic anticoagulation should be avoided. Heparin-free dialysis using intermittent saline flushes is widely adopted as the method of choice for patients at risk of bleeding, although on-line blood predilution may also be used. A new dialyzer, Evodial (Gambro, Lund, Sweden), is grafted with unfractionated heparin during the manufacturing process and may allow safe and efficient heparin-free hemodialysis sessions. In the present trial, Evodial was compared to standard care with either saline flushes or blood predilution.

Methods

The HepZero study is the first international (seven countries), multicenter (10 centers), randomized, controlled, open-label, non-inferiority (and if applicable subsequently, superiority) trial with two parallel groups, comprising 252 end-stage renal disease patients treated by maintenance hemodialysis for at least 3 months and requiring heparin-free dialysis treatments. Patients will be treated during a maximum of three heparin-free dialysis treatments with either saline flushes or blood predilution (control group), or Evodial. The first heparin-free dialysis treatment will be considered successful when there is: no complete occlusion of air traps or dialyzer rendering dialysis impossible; no additional saline flushes to prevent clotting; no change of dialyzer or blood lines because of clotting; and no premature termination (early rinse-back) because of clotting.

The primary objectives of the study are to determine the effectiveness of the Evodial dialyzer, compared with standard care in terms of successful treatments during the first heparin-free dialysis. If the non-inferiority of Evodial is demonstrated then the superiority of Evodial over standard care will be tested. The HepZero study results may have major clinical implications for patient care.

Trial registration

ClinicalTrials.gov NCT01318486

Surface modification of polysulfone based hemodialysis membranes with layer by layer self assembly of polyethyleneimine/alginate-heparin: a simple polyelectrolyte blend approach for heparin immobilization

This study intends to improve blood compatibility of polysulfone (PSF) membranes by generating a nonthrombogenic surface through heparin immobilization. To achieve this task, the support membrane prepared from a blend of PSF and sulfonated polysulfone (SPSF) was modified with layer by layer (LBL) deposition of polyethyleneimine (PEI) and alginate (ALG) and heparin blended with ALG was immobilized only on the outermost surface of the LBL assembly. The results have shown that the adsorption of human plasma proteins and platelet activation on the LBL modified membranes decreased significantly compared with the unmodified PSF and PSF-SPSF blend membranes. Furthermore, blending ALG with a small amount of heparin remarkably prolonged the APTT values of heparin free PEI/ALG coated membranes. It is envisaged that the use of a blend of HEP and ALG only in the terminating layer of the LBL assembly can be an economical and alternative modification technique to create nonthrombogenic surfaces.

Clinical and research markers of oxidative stress in chronic kidney disease

CONTEXT

Kidney-related pathologies have increasing prevalence rates, produce a considerable financial burden, and are characterized by elevated levels of oxidative stress (OS).

OBJECTIVE

This review examines relationships between chronic kidney disease (CKD) and markers of OS and antioxidant status (AS).

METHODS

A systematic review of MEDLINE-indexed clinical trials, randomized controlled trials and comparative studies that examined OS and AS was performed.

RESULTS AND CONCLUSION

Several markers emerged as well-suited indicators of OS and AS in CKD: malondialdehyde, F2-isoprostanes, lipid hydroperoxides, asymmetric dimethylarginine, 8-oxo-7,8-dihydro-2'-deoxyguanosine, protein carbonyls, advanced oxidation protein products and glutathione-related activity.

Heparin-grafted dialysis membrane allows minimal systemic anticoagulation in regular hemodialysis patients: a prospective proof-of-concept study

This prospective, multicenter, proof-of-concept study aimed to evaluate the possibility to reduce the ordinary heparin dose and the systemic anti-Xa activity during hemodialysis (HD) sessions using a new heparin-grafted HD membrane. In 45 stable HD patients, the use of a heparin-grafted membrane with the ordinary heparin dose was followed by a stepwise weekly reduction of dose. Reduction was stopped when early signs of clotting (venous pressure, quality of rinse-back) occurred during two out of three weekly HD sessions. Heparin dose was decreased for 67% of patients resulting in the lowering of these patients' anti-Xa activity by 50%. Dose reductions were achieved with both types of heparin (low-molecular-weight heparin: 64 ± 14 to 35 ± 12 IU/kg, P < 0.0001; unfractionated heparin: 82 ± 18 to 46 ± 13 IU/kg, P < 0.0001) resulting in a decrease of anti-Xa activity at dialysis session end (low-molecular-weight heparin: 0.51 ± 0.25 to 0.25 ± 0.11 IU/mL, P < 0.0001; unfractionated heparin: 0.28 ± 0.23 to 0.13 ± 0.07 IU/mL, P < 0.0001). Failure to further decrease heparin dose was related to signs of clotting in blood lines (57% of sessions), in dialyzer (9%), or both (34%). Significant reduction of heparin dose and anti-Xa activity at the end of HD sessions was possible in stable HD patients using heparin-grafted membrane. HD patients who require low anti-Xa activity at the end of HD sessions might benefit from a heparin-grafted membrane to reduce bleeding risk and other heparin adverse events.

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.