Effects of ultrapure and non-sterile dialysate on the inflammatory response during in vitro hemodialysis

Hemodialysis-Associated Infections

Hemodialysis patients are at increased risk of infections, which are common adverse events among this patient population. We review factors contributing to infections among hemodialysis patients and epidemiology of common infections and outbreaks, including bloodstream infections, vascular access infections, and infections caused by bloodborne pathogens. Recommendations for prevention are discussed with emphasis on essential infection control practices for hemodialysis settings.

NT-proBNP: is it a more significant risk factor for mortality than troponin T in incident hemodialysis patients?

Numerous studies have demonstrated that cardiac biomarkers are significant predictors of cardiovascular (CV) and all-cause mortality in ESRD patients, but most of the studies were retrospective or included small numbers of patients, only prevalent dialysis patients, or measured 1 or 2 biomarkers. This study was to analyze the association between 3 cardiac biomarkers and mortality in incident HD patients. A prospective cohort of 864 incident HD patients was followed for 30 months. Based on the median values of baseline NT-proBNP, cTnT, and hsCRP, the patients were divided into "high" and "low" groups, and CV and all-cause mortality were compared between each group. Additionally, time-dependent ROC curves were constructed, and the NRI and IDI of the models with various biomarkers were calculated. The CV survival rates were significantly lower in the "high" NT-proBNP and cTnT groups compared to the corresponding "low" groups, while there was no significant difference in CV survival rate between the 2 hsCRP groups. However, all-cause mortality rates were significantly higher in all 3 "high" groups compared to each lower group. In multivariate analyses, only Ln NT-proBNP was found to be an independent predictor of mortality. Moreover, NT-proBNP was a more prognostic marker for mortality compared to cTnT. In conclusion, NT-proBNP is the biomarker that results in the most added prognostic value on top of traditional risk factors for CV and all-cause mortality in incident HD patients.

Cardiorenal syndrome type 4: a review

There is a bidirectional and complex relationship between the heart and kidneys. This interaction is physical, chemical as well as biological and is also reflected in a strong connection between renal and cardiovascular diseases. Cardiorenal syndrome type 4 (CRS type 4) is characterized by primary chronic kidney disease (CKD) leading to an impairment of cardiac function, with ventricular hypertrophy, diastolic dysfunction, and/or increased risk of adverse cardiovascular events. The incidence of CKD is increasing, and CRS type 4 is becoming a major public health problem associated with a high morbidity and mortality. In this study, we briefly review the epidemiology and pathophysiology of CRS type 4, the role of biomarkers in its early identification, and its management.

The relationship between neutrophil-to-lymphocyte ratio and vascular calcification in end-stage renal disease patients

Chronic inflammation was found to be correlated with coronary (CAC) and thoracic peri-aortic calcification (TAC) in end-stage renal disease (ESRD) patients. Neutrophil-to-lymphocyte ratio (NLR) was introduced as a potential marker to determine inflammation in cardiac and noncardiac disorders. Data regarding NLR and its association with TAC and CAC are lacking. We aimed to determine the relationship between NLR and vascular calcification in ESRD patients. This was a cross-sectional study involving 56 ESRD patients (22 females, 34 males; mean age, 49.9 ± 14.2 years) receiving peritoneal dialysis or hemodialysis for ≥6 months in the Dialysis Unit of Necmettin Erbakan University. TAC and CAC scores were measured by using an electrocardiogram-gated 64-multidetector computed tomography. NLR was calculated as the ratio of the neutrophils and lymphocytes. There was a statistically significant correlation between NLR, TACS and CACS in ESRD patients (r = 0.43, P = 0.001 and r = 0.30, P = 0.02, respectively). The stepwise linear regression analysis revealed that age, as well as NLR were independent predictors of TACS. However, increased age was the only independent predictor of CACS according to linear regression analysis. Simple calculation of NLR can predict vascular calcification in ESRD patients.

Hemodialysis and water quality

Over 383,900 individuals in the U.S. undergo maintenance hemodialysis that exposes them to water, primarily in the form of dialysate. The quality of water and associated dialysis solutions have been implicated in adverse patient outcomes and is therefore critical. The Association for the Advancement of Medical Instrumentation has published both standards and recommended practices that address both water and the dialyzing solutions. Some of these recommendations have been adopted into Federal Regulations by the Centers for Medicare and Medicaid Services as part of the Conditions for Coverage, which includes limits on specific contaminants within water used for dialysis, dialysate, and substitution fluids. Chemical, bacterial, and endotoxin contaminants are health threats to dialysis patients, as shown by the continued episodic nature of outbreaks since the 1960s causing at least 592 cases and 16 deaths in the U.S. The importance of the dialysis water distribution system, current standards and recommendations, acceptable monitoring methods, a review of chemical, bacterial, and endotoxin outbreaks, and infection control programs are discussed.

Device for continuous extracorporeal blood purification using target-specific metal nanomagnets

BACKGROUND

The present work illustrates how magnetic separation-based blood purification using ultra-strong iron nanomagnets can be implemented into an extracorporeal blood purification circuit. By this promising technique, today's blood purification may be extended to specifically filter high-molecular compounds without being limited by filter cut-offs or column surface saturation.

METHODS

Blood spiked with digoxin (small molecule drug) and interleukin-1β (inflammatory protein) was circulated ex vivo through a device composed of approved blood transfusion lines. Target-specific nanomagnets were continuously injected and subsequently recovered with the aid of a magnetic separator before recirculating the blood.

RESULTS

Magnetic blood purification was successfully carried out under flow conditions: already in single-pass experiments, removal efficiencies reached values of 75 and 40% for digoxin and interleukin-1β, respectively. Circulating 0.5 L of digoxin-intoxicated blood in a closed loop, digoxin concentration was decreased from initially toxic to therapeutic concentrations within 30 min and purification extents of 90% were achieved after 1.5 h.

CONCLUSIONS

Magnetic separation can be successfully implemented into an extracorporeal blood purification device. Simultaneous and specific filtering of high-molecular compounds may offer promising new therapeutic tools for the future treatment of complex diseases, such as sepsis and autoimmune disorders.

Review Article: is it time to embrace haemodiafiltration for centre-based haemodialysis?

Improvements in survival in dialysis patients over the past few decades have been disappointing. Recent prospective trials such the haemodialysis study have not shown conclusive improvements. Two recent observational studies have found a striking survival advantage for haemodiafiltration (HDF). This review covers the differences between HDF and conventional haemodialysis (HD) and the history of the technological advances in the HDF technique. In addition, it explores the putative benefits of HDF over HD. While the observational studies provide a basis for optimism that HDF will provide benefit to dialysis patients, definitive conclusions cannot be drawn until the results of randomized controlled trials are available. While the evidence in favour of HDF at this stage is observational only, there are no studies suggesting that the treatment is detrimental. The use of HDF should probably be increased, particularly in centres where an increase in the frequency and duration of dialysis cannot be readily achieved.

Nutritional and anti-inflammatory interventions in chronic heart failure

Currently, there are 5 million individuals with chronic heart failure (CHF) in the United States who have poor clinical outcomes, including high death rates. Observational studies have indicated a reverse epidemiology of traditional cardiovascular risk factors in CHF; in contrast to trends seen in the general population, obesity and hypercholesterolemia are associated with improved survival. The temporal discordance between the overnutrition (long-term killer) and undernutrition (short-term killer) not only can explain some of the observed paradoxes but also may indicate that malnutrition, inflammation, and oxidative stress may play a role that results in protein-energy wasting contributing to poor survival in CHF. Diminished appetite or anorexia and nutritional deficiencies may be both a cause and a consequence of this so-called malnutrition-inflammation-cachexia (MIC) or wasting syndrome in CHF. Neurohumoral activation, insulin resistance, cytokine activation, and survival selection-resultant genetic polymorphisms also may contribute to the prominent inflammatory and oxidative characteristics of this population. In patients with CHF and wasting, nutritional strategies including amino acid supplementation may represent a promising therapeutic approach, especially if the provision of additional amino acids, protein, and energy includes nutrients with anti-inflammatory and antioxidant properties. Regardless of the etiology of anorexia, appetite-stimulating agents, especially those with anti-inflammatory properties such as megesterol acetate or pentoxyphylline, may be appropriate adjuncts to dietary supplementation. Understanding the factors that modulate MIC and body wasting and their associations with clinical outcomes in CHF may lead to the development of nutritional strategies that alter the pathophysiology of CHF and improve outcomes.

The malnutrition and inflammation axis in pediatric patients with chronic kidney disease

Malnutrition and inflammation are closely linked in adult chronic kidney disease (CKD) patients and are both related to poor outcome, but data on pediatric patients are lacking. To describe the prevalence of inflammation, evaluate nutritional status, their correlation to each other, and their possible determinants in pediatric patients with CKD in predialysis, on hemodialysis (HD), and peritoneal dialysis (PD) who were submitted to demographic, nutritional, and inflammatory evaluations. Patients' nutritional status was evaluated according to anthropometric parameters and body composition assessed by measurements of skinfold thickness and bioelectrical impedance. Inflammation was assessed by measurement of highly sensitive C-reactive protein (CRP), ferritin, and albumin. Patients with CRP > 1 mg/l were considered inflamed. Sixty-four pediatric patients (mean age 9 +/- 4 years-, 40% on HD, 22% on PD, and 38% predialysis) were studied. Mean CRP concentration was 3.4 +/- 6.5 mg/l (median 0.78 mg/l, range 0.78-33.4 mg/l), and 41% presented CRP levels above 1 mg/l. Mean ferritin was 148 +/- 197 mg/dl and was above the normal reference values in 28% of patients. On the other hand, mean albumin was 3.9 +/- 0.5 mg/dl, below reference value in only 13% of patients. A larger proportion of HD patients (52%) were inflamed compared with those on PD (31%; p < 0.05). Malnutrition prevalence varied from 5% to 65% according to the method used. While inflamed patients presented lower serum bicarbonate and were on HD for a longer time, there were no consistent associations between malnutrition and inflammation. Inflammation is highly prevalent in the pediatric CKD population and was not consistently related to malnutrition. Other risk factors linked to high mortality and morbidity (acidosis and longer time on dialysis) were associated with inflammation. Prospective studies will need to analyze the predictive value of inflammation and malnutrition markers in the pediatric CKD population.

Hepcidin in Anemia and Inflammation in Chronic Kidney Disease

Maintaining the correct iron balance is crucial for health. Our understanding of the molecular control of iron metabolism has increased dramatically over the past 5 years due to the discovery of hepcidin. This is a circulating antimicrobial peptide mainly synthesized in the liver, which has been recently proposed as a factor regulating the uptake of dietary iron and its mobilization from macrophages and hepatic stores. Inflammation causes an increase of production of hepcidin, which is a potent mediator of anemia of chronic diseases. Anemia in chronic kidney disease is mainly due to erythropoietin deficiency but these patients often have a chronic inflammatory state. The aim of this review is to summarize the current knowledge dealing with a possible role of hepcidin in iron metabolism and its regulation, particularly in kidney disease. In addition, current methods of determination of hepcidin are reviewed.

The kidney disease wasting: Inflammation, oxidative stress, and diet-gene interaction

The 350,000 maintenance hemodialysis (MHD) patients in the United States have an unacceptably high mortality rate of >20%/year. Almost half of all deaths are assumed to be cardiovascular. Markers of kidney disease wasting (KDW) such as hypoalbuminemia, anorexia, body weight and fat loss, rather than traditional cardiovascular risk factors, appear to be the strongest predictors of early death in these patients. The KDW is closely related to oxidative stress (SOX). Such SOX markers as serum myeloperoxidase are associated with pro-inflammatory cytokines and poor survival in MHD patients. Identifying the conditions that modulate the KDW/SOX-axis may be the key to improving outcomes in MHD patients. Dysfunctional lipoproteins such as a higher ratio of the high-density lipoprotein inflammatory index (HII) may engender or aggravate the KDW, whereas functionally intact or larger lipoprotein pools, as in hypercholesterolemia and obesity, may mitigate the KDW in MHD patients. Hence, a reverse epidemiology or "bad-gone-good" phenomenon may be observed. Diet and gene and their complex interaction may lead to higher proportions of pro-inflammatory or oxidative lipoproteins such as HII, resulting in the aggravation of the SOX and inflammatory processes, endothelial dysfunction, and subsequent atherosclerotic cardiovascular disease and death in MHD patients. Understanding the factors that modulate the KDW/SOX complex and their associations with genetic polymorphism, nutrition, and outcomes in MHD patients may lead to developing more effective strategies to improve outcomes in this and the 20 to 30 million Americans with chronic disease states such as individuals with chronic heart failure, advanced age, malignancies, AIDS, or cachexia.

UNRESOLVED ISSUES IN DIALYSIS: Ultrapure Dialysate: Facts and Myths

During hemodialysis, blood comes in contact with a large volume of dialysate. Since the purity of dialysate has been linked to acute and long-term complications in hemodialysis patients, the limit of bacterial and endotoxin contamination has been reduced in recent years. Questions have been raised as to whether ultrapure dialysate is required to prevent such complications; in particular, the chronic inflammatory status frequently found in chronically hemodialyzed patients. In vivo and in vitro data suggest that cytokine stimulation in the blood depends on the concentration of bacteria or endotoxin in the dialysate and on the endotoxin permeability of the dialysis membrane. It is not proven whether ultrapure dialysate reduces significantly proinflammatory cytokine generation compared with standard dialysate within the limits of recent recommendations, if rather impermeable dialysis membranes are used. Cuprophane membranes are more permeable to cytokine-inducing substances compared with synthetic membranes such as polysulfone and polyamide. Clinical reports have also attempted to link several acute and chronic complications of hemodialysis to dialysate purity. To date, however, there is no large randomized clinical trial demonstrating that ultrapure dialysate significantly reduces biomarkers of inflammation and other consequential putative complications, including dialysis-related amyloidosis, erythropoietin requirement, and cardiovascular morbidity and mortality. In conclusion, based on the existing clinical data, ultrapure dialysate is recommended in the setting of suboptimal bacteriologic quality of standard dialysate and the use of permeable dialysis membranes.

The Importance of Water Quality and Haemodialysis Fluid Composition

Treatment of renal failure by haemodialysis uses dialysis fluid to facilitate the normalization of electrolyte and acid base abnormalities and the removal of low molecular weight uraemic compounds present in the plasma such as urea. The dialysis fluid is a continuously produced blend of treated tap water and a concentrated solution containing electrolytes, buffer, and glucose. The water used originates as drinking water but undergoes additional treatment. Recent surveys have indicated that the chemical and microbiological content of such water frequently fails to meet the requirements of established standards, and its bacterial content arising from the presence of a biofilm in the water distribution network or the hydraulic circuit of the dialysis machine is a contributory factor to the chronic inflammatory state in patients undergoing regular dialysis. The composition of the dialysis fluid plays an important role in the modulation of complications associated with end-stage renal disease, as well as those associated with the treatment itself. The avoidance of complications arising from water contaminants requires a constant and vigorous attention to water quality, whilst with the composition of electrolytes and buffer there is a trend towards greater individualization to provide a high degree of treatment tolerance.

Serum C-reactive Protein Level Is Associated with Renal Function and It Affects Echocardiographic Cardiovascular Disease in Pre-Dialysis Patients

BACKGROUND

Relevance of serum CRP for morbidity and mortality in pre-dialysis patients has not been assessed extensively. The aim of this study was to determine the incidence of elevated serum CRP in pre-dialysis patients and to identify the factors that associate with serum CRP. We were also evaluated the effects of serum CRP on cardiovascular disease, anemia, and nutritional markers.

METHODS

One hundred and eight pre-dialysis patients with a mean creatinine clearance (CrCl) of 30.1 ml/min were included in the study. Data collected from each patient included demographics, co-morbidity, medications, blood pressures, blood biochemistry including serum CRP, renal function, and echocardiography.

RESULTS

Serum CRP was elevated (>5 mg/l) in 43 patients (39.8%). There was a negative correlation between serum CRP and CrCl (r = -0.370, p < 0.001). CrCl was the unique independent factor affecting serum CRP. Serum CRP was an independent factor affecting left ventricular mass index, fractional shortening, serum albumin and hematocrit in multivariate analyses.

CONCLUSIONS

Prevalence of elevated serum CRP in pre-dialysis patients is high. Reduced renal clearance of CRP and/or cytokines may contribute to the inflammatory status. Elevated serum CRP is an important cause of morbidity in pre-dialysis patients.

Chronic kidney disease and inflammation in pediatric patients: from bench to playground

Signs of an activated immune system can be observed already in the early stages of chronic kidney disease (CKD). Markers of a chronically activated immune system are closely linked to several complications of CKD, such as accelerated atherosclerosis, vascular calcification, insulin resistance, increased muscle catabolism, loss of appetite, bone remodeling, and increased peritoneal permeability. Interestingly, all the aforementioned pathological states resemble a state of accelerated ageing and are strongly associated with increased morbidity and mortality in CKD patients. In recent studies, signs of inflammation have been shown as predictors for mortality in dialysis patients, and the role of inflammation as a risk factor for complications of CKD in children has emerged. Although preliminary findings suggest that inflammation is highly prevalent in the pediatric population with CKD, information related pathogenic links and to clinical outcomes is lacking. For the future, it is crucial for investigations to address the mechanisms and complications of inflammation that are manifested in pediatric patients with CKD in all stages. Since early identification and intervention may generate the most efficient strategies for prevention and treatment of cardiovascular disease in CKD patients, the pediatric population deserves special attention in future studies. In this review, we discuss the mechanisms involved in the inflammatory activation and the main causes and consequences of the inflammatory state observed in the CKD patient, with special emphasis on the pediatric population.

Inflammation: cause of vascular disease and malnutrition in dialysis patients

Inflammation occurs in response to tissue injury or the presence of foreign antigens and is important in the mobilization of specific immunologic and nonimmunologic defenses against injury. The vascular endothelium is altered to allow immune competent cells to access the interstitial space. Muscle and visceral proteins are catabolized and the amino acids are used either to supply energy or as substrates for the production of acute-phase proteins that play a role in defense. Restoration of muscle mass is impaired while inflammation is on going. Lipids are mobilized. Although serving a vital role in allowing host survival from acute injury or infection, if unimpeded, or if triggered inappropriately, the acute-phase response may instead lead to increased vascular injury and progressive loss of muscle and visceral protein pools causing malnutrition. Markers of inflammation (C reactive protein [CRP] or interleukin-6 [IL-6] levels) are associated with cardiovascular risk in the general population and in dialysis patients. Hypoalbuminemia also is associated with cardiovascular risk in dialysis patients. Although albumin is considered a marker of nutrition, changes in albumin levels are associated with increased levels of acute-phase proteins. Persistent changes in albumin levels are caused by reduced albumin synthesis associated with inflammation and not decreased normalized protein catabolic rate. The cause(s) of inflammation must be identified and treated to resolve malnutrition and reduce cardiovascular risk.

Biomaterial-associated thrombosis: roles of coagulation factors, complement, platelets and leukocytes

Our failure to produce truly non-thrombogenic materials may reflect a failure to fully understand the mechanisms of biomaterial-associated thrombosis. The community has focused on minimizing coagulation or minimizing platelet adhesion and activation. We have infrequently considered the interactions between the two although we are generally familiar with these interactions. However, we have rarely considered in the context of biomaterial-associated thrombosis the other major players in blood: complement and leukocytes. Biomaterials are known agonists of complement and leukocyte activation, but this is frequently studied only in the context of inflammation. For us, thrombosis is a special case of inflammation. Here we summarize current perspectives on all four of these components in thrombosis and with biomaterials and cardiovascular devices. We also briefly highlight a few features of biomaterial-associated thrombosis that are not often considered in the biomaterials literature: The importance of tissue factor and the extrinsic coagulation system. Complement activation as a prelude to platelet activation and its role in thrombosis. The role of leukocytes in thrombin formation. The differing time scales of these contributions.

Renal Amyloidosis Is Associated with Increased Mortality in Hemodialysis Patients

AIM

The aim of the study was to investigate the risk factors for mortality of hemodialysis (HD) patients at Baskent University Hospital, HD Center in Ankara, Turkey.

METHODS

We prospectively followed 203 stable HD patients for 42 months. Population characteristics (age, gender, duration of HD, causes of end stage renal disease [ESRD]) and biochemical variables were included in the study. Mortality was prospectively monitored.

RESULTS

Sixty-one patients died over 42 months. Cardiovascular events and infections/septicemia were the most common causes of death. The nonsurvivors had significantly lower hemoglobin (Hb), parathyroid hormone (PTH), creatinine, albumin, and prealbumin levels and higher age and higher C-reactive protein (CRP) levels. Survival curves as obtained by the Kaplan-Meier method in the groups of causes of ESRD (renal amyloidosis [RA], diabetes mellitus [DM], hypertension [HT] + atherosclerotic kidney disease [AKD], and others) showed that patients with DM and RA had the worst prognosis during the follow-up period. In the multivariate Cox proportional hazards model, RA and DM were found to be independent risk factors for death in HD patients together with high CRP and low albumin and prealbumin levels. Infection/septicemia is the leading cause of mortality in patients with DM and RA.

CONCLUSION

The results of this study indicate that the presence of RA and DM as underlying renal diseases are independent predictors of mortality in our HD patients along with poor nutritional status and activated inflammatory response.

Inflammation and nutrition in renal insufficiency

Protein-energy malnutrition (PEM) and inflammation are common in patients with chronic kidney disease (CKD) and worsen as the CKD progresses toward the end-stage renal disease (ESRD). These conditions are major predictors of poor clinical outcome in kidney failure, as reflected by a strong association between hypoalbuminemia and cardiovascular disease (CVD). It has been suggested that inflammation is the cause of both PEM and CVD and, hence, the main link among these conditions, but these hypotheses are not well established. Increased release or activation of inflammatory cytokines, such as interleukin-6 or tumor necrosis factor alpha, may suppress appetite, cause muscle proteolysis and hypoalbuminemia, and may be involved in atherogenesis. Increasing serum levels of proinflammatory cytokines caused by reduced renal function, volume overload, oxidative or carbonyl stress, decreased levels of antioxidants, increased susceptibility to infection in uremia, and the presence of comorbid conditions may lead to inflammation in CKD patients. In hemodialysis patients, the exposure to dialysis tubing and dialysis membranes, poor quality of dialysis water, back-filtration or back-diffusion of contaminants, and foreign bodies in dialysis access maybe additional causes of inflammation. Similarly, episodes of overt or latent peritonitis, peritoneal dialysis (PD) catheter and its related infections, and constant exposure to PD solution may contribute to inflammation in these patients. The degree to which PEM in dialysis patients is caused by inflammation is not clear. Because both PEM and inflammation are strongly associated with each other and can change many nutritional measures and outcome concurrently in the same direction, the terms malnutrition-inflammation complex syndrome (MICS) and/or malnutrition-inflammation-atherosclerosis (MIA) have been suggested to denote the important contribution of both of these conditions to poor clinical outcome. Maintenance dialysis patients who are underweight or who have low serum levels of cholesterol, creatinine, or homocysteine may be suffering from the MICS/MIA and its subsequent poor outcome. Consequently, obesity and hypercholesterolemia may appear protective, which is known as reverse epidemiology. Although MICS/MIA may have a significant contribution in reversing the traditional CVD risk factors in dialysis patients, it is not clear whether PEM or inflammation and their complications can be effectively managed in CKD and ESRD or whether their management improves clinical outcome.

Pyrogen transfer across high- and low-flux hemodialysis membranes

The extent to which bacterial products from contaminated dialysate enter a patient's blood depends upon the type and permeability of the hemodialysis membrane in use. This study was performed to assess the transfer of pyrogenic substances across both high- and low-flux membranes (DIAPES, Fresenius Polysulfone, Helixone, Polyamide S). All experiments were carried out in the saline-saline model. The dialysate pool was contaminated either with purified lipopolysaccharide (LPS) (250 and 500 EU/mL) or with sterile bacterial culture filtrates (20 EU/mL), and in vitro dialysis was performed under diffusive and convective conditions. A significant transfer of endotoxin was observed for both low- and high-flux DIAPES challenged with either LPS or with bacterial culture filtrates. Under identical conditions, no transfer of endotoxins was detectable across Fresenius Polysulfone and Helixone upon challenge with purified LPS. With bacterial culture filtrates, endotoxin concentrations for Polyamide S and Fresenius Polysulfone were about 10% and 1%, respectively, of those measured for DIAPES, whereas no transfer of endotoxin was detectable for Helixone. Using an alternative assay (induction of interleukin-1 receptor antagonist, IL-1Ra, in whole blood), only the DIAPES membrane showed the passage of cytokine-inducing substances. Thus, when saline is present in both the blood and dialysate compartments (i.e., the situation during predialysis priming procedures), dialysis membranes differ profoundly with respect to their permeability to endotoxins.

Characteristics and effects of inflammation in end-stage renal disease

Malnutrition and cardiovascular disease are associated with end-stage renal disease (ESRD) and both are closely associated with one another, both in cross-sectional analysis and when the courses of individual patients are followed over time. Inflammation, by suppressing synthesis of albumin, transferrin, and other negative acute-phase proteins and increasing their catabolic rates, either combines with modest malnutrition or mimics malnutrition, resulting in decreased levels of these proteins in dialysis patients. Inflammation also leads to reduced muscle mass by increasing muscle protein catabolism and blocking synthesis of muscle protein. More importantly, inflammation alters plasma protein composition and endothelial structure and function so as to promote vascular disease. Markers of inflammation, C-reactive protein (CRP), and interleukin (IL)-6 powerfully predict death from all causes and from cardiovascular disease in dialysis patients as well as progression of vascular injury. The causes of inflammation are likely multifactorial, including oxidative modification of plasma proteins, interaction of blood with nonbiocompatible membranes and lipopolysaccharides in dialysate, subclinical infection of vascular access materials, oxidative catabolism of endothelium-derived nitric oxide, and other infectious processes. Treatment should be focused on identifying potential causes of inflammation, if obvious, and reduction of other risk factor for cardiovascular disease.

The influence of patient- and facility-specific factors on nutritional status and survival in hemodialysis

BACKGROUND

Parameters of nutritional status, including serum albumin, serum creatinine, and body mass index (BMI), are powerful predictors of mortality and hospitalization in patients with end stage renal disease (ESRD). Patient-specific characteristics and facility-related practice patterns modify certain parameters of nutritional status. We aimed to determine whether patient and facility characteristics modify the risk profiles associated with malnutrition in hemodialysis patients.

METHODS

We analyzed data on 5,234 prevalent hemodialysis patients from the Dialysis Morbidity and Mortality Study (DMMS) Wave 1 for whom information on demographic, clinical, nutritional, and facility-related characteristics were available. We evaluated the associations among facility characteristics and serum albumin, serum creatinine, and BMI, adjusting for the effects of age, sex, race/ethnicity, diabetes, and dialysis vintage. We determined correlates of mortality and hospitalization, focusing on nutritional parameters, facility effects, and the interactions among patient-specific and facility-specific characteristics, albumin, creatinine, and BMI.

RESULTS

Serum albumin was lower with older age, diabetes, nonblack race, and hemodialysis using a catheter. Serum albumin was higher with annual vascular access surveillance, higher BMI among women, higher urea reduction ratio, among patients in whom dialyzers were reprocessed (particularly with bleach), among dialysis units in which water purification was used, and when vascular access blood flow rates were > or =350 mL/min. Overall survival was decreased with lower albumin, creatinine, and BMI. There were interactions among albumin, age, and vintage. Whereas lower serum albumin concentrations consistently were associated with an increased risk of death, the differences were attenuated among older patients and accentuated among patients of longer vintage.

CONCLUSION

Some facility-specific factors are associated with nutritional parameters including serum albumin, serum creatinine, and BMI. The associations of nutritional parameters with mortality and hospitalization vary by age, sex, and vintage but not by facility-specific factors, including those associated with the nutritional parameters themselves.

Inflammation in end-stage renal disease: sources, consequences, and therapy

Cardiovascular disease (CVD) remains the main cause of morbidity and mortality in patients with end-stage renal disease (ESRD). Although traditional risk factors are common in ESRD patients, they alone may not be sufficient to account for the high prevalence of CVD in this condition. Recent evidence demonstrates that chronic inflammation, a nontraditional risk factor which is commonly observed in ESRD patients, may cause malnutrition and progressive atherosclerotic CVD by several pathogenetic mechanisms. The causes of inflammation in ESRD are multifactorial and, while it may reflect underlying CVD, an acute-phase reaction may also be a direct cause of vascular injury by several pathogenetic mechanisms. Available data suggest that proinflammatory cytokines play a central role in the genesis of both malnutrition and CVD in ESRD. Thus it could be speculated that suppression of the vicious cycle of malnutrition, inflammation, and atherosclerosis (MIA syndrome) would improve survival in dialysis patients. Recent evidence has demonstrated strong associations between inflammation and both increased oxidative stress and endothelial dysfunction in ESRD patients. As there is not yet any recognized, or even proposed, treatment for ESRD patients with chronic inflammation, it would be of obvious interest to study the long-term effect of various anti-inflammatory treatment strategies on the nutritional and cardiovascular status as well as outcome in these patients.

Lipopolysaccharide concentrations during superflux dialysis using unfiltered bicarbonate dialysate

In the present report, the design of a new dialysate delivery system to produce low to moderately contaminated dialysate is described. In addition, the first data on bacterial counts and lipopolysaccharide (LPS) concentrations in both the dialysate and the blood during hemodialysis (HD) with superflux dialyzers are presented. In this prospective study, 37 patients were randomized into two consecutive periods of 12 weeks to HD with a high flux polysulfon (PS), a superflux PS, a superflux cellulosic tri-acetate (CTA) or a superflux CTA dialyzer with filtered dialysate (CTAf), resulting in 74 periods in which measurements were obtained. Filtered dialysate showed significantly lower bacterial counts, if compared with nonfiltered dialysate (p < 0.001). As for LPS, marked differences were not observed between filtered and nonfiltered dialysate, whereas mean plasma LPS concentrations were below the value of the dialysate at all time points (p < 0.001). Plasma LPS concentrations decreased significantly during HD with all four modalities (F 60: t0 0.032+/-0.005, t180 0.026+/-0.009 endotoxin units (EU)/ml, p = 0.001; F 500S, t0 0.031+/-0.004, t180 0.027+/-0.005 EU/ml, p = 0.001; Tricea 150G: t0 0.032+/-0.004, t180 0.025+/-0.005 EU/ml, p < 0.001; and Tricea 150Gf: t0 0.034+/-0.007, t180 0.025+/-0.006 EU/ml, p < 0.001). During HD with highly permeable dialyzers and moderately contaminated dialysate, plasma LPS concentrations decreased significantly, irrespective of the material used (PS or CTA), the flux characteristics of the devices (high flux or superflux), or the presence of a bacterial filter.

Nutritional status in dialysis patients: a European consensus

BACKGROUND

Malnutrition is common in dialysis patients and closely related to morbidity and mortality. Therefore, assessment of nutritional status and nutritional management of dialysis patients play a central role in everyday nephrological practice.

METHODS

Achieving a consensus on key points relating to pathogenesis, clinical assessment, and nutritional management of dialysis patients.

RESULTS

The assessment of nutritional status should be based on clinical assessment and biochemical parameters, including history of weight loss, per cent standard weight, body mass index, muscle mass, subcutaneous fat mass, and plasma albumin, creatinine, bicarbonate and cholesterol. Co-morbid conditions should be assessed and C-reactive protein (CRP) measured--as a marker of inflammation--as there is a close relation between malnutrition, on one side, and co-morbid conditions and inflammation on the other. For a more detailed assessment, subjective global assessment of nutritional status is a well-validated tool, and dual-energy X-ray absorptiometry (DEXA) is a useful method for routine assessment of lean body mass. Anthropometric methods are also useful. They are cheap and easy to apply, although less precise than DEXA. The recommended daily protein intake is at least 1.2 g/kg standard body weight and the energy intake 35 kcal/kg standard body weight (BW), in patients <60 years, and 30 kcal/kg standard BW in patients >60 years. The standard bicarbonate level should be at least 22 mmol/l. If CRP is >10 mg/l, it is important to seek and treat the underlying cause. Adequate dialysis (for haemodialysis: Kt/V >1.2) should be ensured and, although no definite evidence of the importance of dialysis water quality is available, the opinion of the authors is that the water quality should be high. The role of the biocompatibility of the dialysis membrane is still not clear. The dietitian plays a pivotal role in the nutritional care of dialysis patients, and patients should be provided with dietary counselling from the start of substitutive treatment in order to meet the recommended nutritional intakes. Dietary counselling can also play an important role in an integrated treatment of hyperphosphataemia, although most patients will also need phosphate binders if they have an adequate protein intake.

CONCLUSION

Malnutrition assessment and treatment is a great challenge for nephrological care. Achieving evidence-based consensus can help in implementing the progress of knowledge in clinical practice.

NUTRITIONALMANAGEMENT OFMAINTENANCEDIALYSISPATIENTS: Why Aren't We Doing Better?

About 40% of patients undergoing maintenance dialysis suffer from varying degrees of protein-energy malnutrition. This is a problem of substantial importance because many measures of nutritional status correlate with the risk of morbidity and mortality. There are many causes of protein-energy malnutrition in maintenance dialysis patients. Evidence indicates that nutritional decline begins even when the reduction in glomerular filtration rate is modest, and it is likely that the observed decrease in dietary protein and energy intake plays an important role. The nutrient intake of patients receiving maintenance dialysis also is often inadequate, and several lines of evidence suggest that toxins that accumulate with renal failure suppress appetite and contribute to nutritional decline once patients are on maintenance dialysis. Recent epidemiologic studies have suggested that both increased serum levels of leptin and inflammation may reduce nutrient intake and contribute to the development of protein-energy malnutrition. It is likely that associated illnesses, which are highly prevalent, contribute to malnutrition in maintenance dialysis patients. Recent data from the United States Renal Data System registry suggest that in the United States, the mortality rate of dialysis patients is improving. However, it remains high. We offer suggestions for predialysis and dialysis care of these patients that can result in improvement in their nutritional status. Whether this improvement will result in a decrease in patient morbidity and mortality is unknown.

The microinflammatory state in uremia: causes and potential consequences

Mortality is markedly elevated in patients with end-stage renal disease. The leading cause of death is cardiovascular disease. Lipoprotein levels are only slightly elevated in dialysis patients, and cardiovascular risk is inversely correlated with serum cholesterol, suggesting that a process other than hyperlipidemia plays a role in the incidence of cardiovascular disease. Hypoalbuminemia, ascribed to malnutrition, has been one of the most powerful risk factors that predict all-cause and cardiovascular mortality in dialysis patients. The presence of inflammation, as evidenced by increased levels of specific cytokines (interleukin-6 and tumor necrosis factor alpha) or acute-phase proteins (C-reactive protein and serum amyloid A), however, has been found to be associated with vascular disease in the general population as well as in dialysis patients. The process of inflammation, also called the acute-phase response, additionally causes loss of muscle mass and changes in plasma composition-decreases in serum albumin, prealbumin, and transferrin levels, also associated with malnutrition. Inflammation alters lipoprotein structure and function as well as endothelial structure and function to favor atherogenesis and increases the concentration of atherogenic proteins in serum, such as fibrinogen and lipoprotein (a). Inflammation in dialysis patients is episodic. The causes are likely to be multifactorial and include vascular access infection, less-than-sterile dialysate, dialysate back leak, and nonbiocompatible membranes in addition to clinically apparent infection. In addition, proinflammatory compounds, such as advanced glycation end products, accumulate in renal failure, and defense mechanisms against oxidative injury are reduced, contributing to inflammation and to its effect on the vascular endothelium.

Ultrapure dialysate: a desirable and achievable goal for routine hemodialysis

United States standards for the microbiologic quality of dialysate are not very stringent and have remained unchanged for more than 20 years, despite significant changes in the patient population and in the technology of hemodialysis. Numerous studies have demonstrated that bacterial products can cross dialysis membranes and stimulate an inflammatory response in the patient. Inflammation has been implicated in several complications associated with long-term hemodialysis therapy, and the use of ultrapure dialysate has been shown to reduce the incidence of one of these complications, beta2-microglobulin amyloidosis. Since technological innovations in water treatment and improvements in dialysis machine design allow the routine production of ultrapure dialysate, its use should now become standard.

Impaired monocyte CD11b expression in interstitial inflammation in hemodialysis patients

BACKGROUND

It is not known to what extent intravascular phenotypic alterations in adhesion molecule expression induced by hemodialysis influence the recruitment of monocytes and their ability to up-regulate CD11b at the local site of inflammation in the interstitium. Using a skin suction chamber technique, we addressed these issues in eight hemodialysis patients and in eight healthy subjects.

METHODS

Two skin blisters were raised on the forearm of each individual and blister exudate collected. The blisters were then stimulated with autologous serum (active blister, intense inflammation) or buffer (control blister, intermediate inflammation), respectively. Thereafter the patients were treated with Cuprophan hemodialysis for four hours. After 10 hours, the exudate was aspirated from each chamber in all subjects. Monocyte count and expression of CD11b were analyzed in serum and blister fluid by flow cytometry. Then, monocytes from healthy blood donors were incubated in blister fluid from patients and healthy subjects in order to determine the local chemotactic activity in terms of CD11b up-regulation. Monocyte chemotactic protein-1 (MCP-1), a marker of systemic monocyte chemotactic activity, was also analyzed in serum at 0 and 10 hours in all individuals.

RESULTS

The number of monocytes at the site of inflammation in the interstitium in hemodialysis patients correlated with the expression of CD11b on transmigrated cells (r = 0.78, P < 0.001). Monocytes collected in the active blister fluid of dialysis patients expressed equal levels of CD11b as cells collected from healthy subjects. By contrast, monocytes collected from the control blisters of patients expressed lower levels of CD11b than cells from healthy subjects (P < 0.01), despite equal interstitial biological activity of CD11b-mobilizing factors in blister fluid from patients and healthy subjects and the fact that patients had higher systemic chemotactic activity in terms of MCP-1 concentration in serum (P < 0.001).

CONCLUSION

Monocytes from hemodialysis patients have the capacity to mobilize CD11b to the same extent as cells from healthy individuals at the inflammatory spot, but more intense stimuli are required for such actions, probably because of a transient refractoriness.

Relationship between IL-1beta and TNFalpha production by PBMC and clinical features of hemodialysis patients

The relationship between production of IL-1beta and TNFalpha by peripheral blood mononuclear cells (PBMC) of hemodialysis (HD) patients and clinical disorders characteristic for HD patients was examined. The study included 28 HD patients divided in the 4 groups: group 1--6 patients with malnutrition; group 2--6 patients with secondary hyperparathyroidism; group 3--6 patients with eosinophilia; group 4--10 stable HD patients without clinical complication. The control group consisted of 9 healthy volunteers. All patients were dialyzed with cuprophane membrane more than one years. Blood samples were taken immediately before the beginning of hemodialysis and PBMC were isolated by centrifugation on the density gradient. Concentrations of IL-1beta and TNFalpha were measured in the supernatants of the cultures by ELISA tests. The results showed marked individual differences in cytokine production both in healthy controls and in HD patients. Spontaneous and LPS stimulated production of IL-1beta by PBMC of HD patients was significantly higher compared to PBMC of healthy controls. There were no significant differences between group of patients with different clinical complications in cytokine production. However, a positive correlation was found between IL-1beta concentration and body mass index for patients with malnutrition and between concentration of IL-1alpha and parathyroid hormone (PTH) for patients with secondary hyperparathyroidism. The results suggest that PBMC of HD patients are chronically stimulated to produce IL-1beta, which may contribute to the development of particular chronic complications.

Effects of dialyser and dialysate on the acute phase reaction in clinical bicarbonate dialysis

BACKGROUND

In chronic haemodialysis (HD), morbidity may result from repetitive induction of the acute phase response, caused by a bioincompatible dialysis membrane and/or contaminated dialysate. In the present study, cytokine release (interleukin-6, IL-6) and subsequent production of acute phase proteins (C-reactive protein, CRP and secretory phospholipase A(2), sPLA(2)) were assessed to investigate whether the HD-induced acute phase reaction depends mainly on the type of membrane or on the sterility of the dialysate.

METHODS

In 11 patients, IL-6, CRP and sPLA(2) levels were assessed in blood samples drawn before (t(0)), at the end (t(180)) and 24 h after the start of HD (t(1440)). All patients were dialysed on Cuprammonium (CU) and Polysulphon (PS) dialysers and seven patients underwent an additional HD session on CU plus a dialysate filter (CUf).

RESULTS

IL-6 levels were increased significantly at t(180) compared with t(0) (P<0.02) with both CU and CUf. At t(1440), IL-6 levels had returned to baseline. In contrast, marked fluctuations did not occur during HD with PS. At t(180), IL-6 was significantly greater with CU and CUf devices, than with PS (P<0.02). Following HD with CU and CUf, a significant increase in CRP was observed at t(1440), compared with postdialysis values (P</=0.05). In addition, sPLA(2) values were markedly increased at t(1440), compared with t(180), but only significant in the case of CU (P=0.01). IL-6 levels at t(180) were significantly correlated with CRP (r=0.50, P<0.01) and sPLA(2) (r=0.47, P=0.01) values at t(1440). During HD with PS membranes, neither CRP nor sPLA(2) values were markedly changed.

CONCLUSIONS

In contrast to PS, both CU and CUf resulted in elevated IL-6 plasma levels at the end of HD, compared with t(0), which correlated with increased CRP and sPLA(2) values 24 h later. Therefore, the type of membrane, rather than the bacterial quality of the dialysate, seems to be responsible for the induction of the acute phase response during clinical bicarbonate HD.

Whole blood production of monocytic cytokines (IL-1beta, IL-6, TNF-alpha, sIL-6R, IL-1Ra) in haemodialysed patients

BACKGROUND

The production of monocytic cytokines by isolated mononuclear cells after stimulation by phytohaemagglutinin (PHA) and lipopolysaccharide (LPS) is generally increased in haemodialysed (HD) patients. We performed whole blood (WB) cultures to evaluate cytokine production by blood cells inside their complex cellular and humoral network.

METHODS

Diluted whole blood from HD patients (collected before dialysis) and controls was cultured alone with PHA (2.5 microg/ml) or LPS (1 and 3 microg/ml). Supernatants were collected after 24 and 48 h of culture, and concentrations of IL-1 beta, IL-6, TNF-alpha, sIL-6R and IL-1Ra were determined by ELISA.

RESULTS

The low spontaneous production of IL-1beta, IL-6 and TNF-alpha in both patients and controls was not significantly modified by PHA. The lower dose of LPS (1 microg/ml) induced a significant but lower increase in production of IL-1beta, IL-6 and TNF-alpha in patients than in controls. In contrast, while it did not further increase their production in controls, the higher concentration of LPS (3 microg/ml) still increased their production in patients to the same level than in controls. The plasma concentrations of sIL-6R were higher in patients than in controls. In both groups, the sIL-6R concentration did not vary during the culture period whether the cells were stimulated or not with LPS or PHA. This suggests that the increased plasma levels of sIL-6R were not produced by blood cells. Despite a similar significant LPS and PHA induced production of IL-1Ra, the IL-1Ra/IL-1beta ratio was always higher in patients than in controls.

CONCLUSION

Monocytes from HD patients in WB cultures are hyporesponsive to PHA and LPS for their IL-1beta, TNFalpha and IL-6 production in contrast to isolated monocytes that demonstrate signs of activation. If it reflects the in vivo situation it could partly explain the immune defect in uraemic and haemodialysed patients. Higher sIL-6R/IL-6 and IL-1Ra/IL-1beta ratios could also participate to the complex immune disturbances of HD patients by reducing the biological activity of two cytokines playing a major role in the immune and inflammatory network.