Changes of serum albumin and C-reactive protein are related to changes of interleukin-6 release by peripheral blood mononuclear cells in hemodialysis patients treated with different membranes

A Systematic Review on Hearing and Balance in Patients with Chronic Kidney Disease with and Without Hemodialysis

Objective

Exploring the auditory and vestibular manifestations associated with chronic kidney disease (CKD) has been growing in recent years. Understanding these complaints in CKD patients is crucial for comprehensive patient care. This review aimed to investigate the audiological findings and profiles across various stages of CKD and guide for informed decision-making in their management.

Methods

Relevant articles from PubMed, ScienceDirect, EBSCO Medline, SCOPUS, Google Scholar, and Clinical Key were identified for review. The selected articles were published from 2008 to 2023 and written in English language. A total of 41 articles on auditory and vestibular assessments in CKD were eligible for review.

Results

Pure tone audiometry (PTA), immittance audiometry (IA) and otoacoustic emissions (OAEs) were the most commonly employed hearing tests respectively, with a higher frequency of utilization in hemodialysis cases compared to non-hemodialysis ones. Also, vestibular evoked myogenic potentials (VEMPs) emerged as the most popular vestibular test among hemodialysis patients while questionnaires were frequently employed in CKD patients. Moreover, our analysis suggests a potential association between the duration of hemodialysis and the development of tinnitus and vertigo. Abnormalities were also observed in auditory brainstem response (ABR), speech audiometry, central auditory processing tests and videonystagmography (VNG) assessment in hemodialysis and non-hemodialysis patients.

Conclusion

CKD patients, particularly those undergoing hemodialysis, face a higher risk of hearing loss, tinnitus, and vestibular complaints. Performing otoacoustic emissions and vestibular-evoked myogenic potentials along with PTA on CKD patients, regardless of the disease stage is recommended to more effective management of audiovestibular complaints in these population.

Relationship between Compound α-Ketoacid and Microinflammation in Patients with Chronic Kidney Disease

Chronic kidney disease (CKD) refers to the presence of structural or functional abnormalities in the kidneys that affect health, lasting for more than 3 months. CKD is not only the direct cause of global incidence rate and mortality, but also an important risk factor for cardiovascular disease. Persistent microinflammatory state has been recognized as an important component of CKD, which can lead to renal fibrosis and loss of renal function, and plays a crucial role in the pathophysiology and progression of the disease. Simultaneously, compound α-Ketoacid can bind nitrogen-containing metabolites in the blood and accelerate their excretion from the body, thereby reducing the level of metabolic waste, alleviating gastrointestinal reactions in patients, and reducing the inflammatory response and oxidative stress state of the body. Compound α-Ketoacid contains amino acids required by CKD patients. In this review, we explore the relationship between compound α-Ketoacid and microinflammation in patients with CKD. The review indicated that compound α-Ketoacid can improve the microinflammatory state in CKD patients by improving the nutritional status of CKD patients, improving patient's acid-base balance disorder, regulating oxidative stress, improving gut microbiota, and regulating abnormal lipid metabolism.

Plasma glycocalyx pattern: a mirror of endothelial damage in chronic kidney disease

Background

Endothelial damage and cardiovascular disease complicate chronic kidney disease (CKD). The increased atherogenicity observed in patients with CKD can be linked to microinflammation and endothelial damage. Circulating endothelial glycocalyx degradation products, such as perlecan and decorin, tend to be elevated in CKD. We aimed to explore the association between the plasma perlecan and decorin levels and this pro-inflammatory and atherogenic state by studying monocyte subpopulations and intracellular adhesion molecule (ICAM)-1 expression in patients with CKD.

Methods

We studied 17 healthy controls, 23 patients with advanced CKD, 25 patients on haemodialysis, 23 patients on peritoneal dialysis and 20 patients who underwent kidney transplantation. Perlecan and decorin levels were evaluated using enzyme-linked immunosorbent assays, and the monocyte phenotype was analysed using direct immunofluorescence and flow cytometry.

Results

The plasma perlecan levels were higher in patients with CKD than in the healthy controls. These levels were associated with a higher prevalence of ICAM-1+ monocytes. Conversely, patients with advanced CKD (pre-dialysis) had higher plasma decorin levels, which were associated with a reduced ICAM-1 expression per monocyte.

Conclusions

Elevated perlecan levels in CKD may be associated with a higher prevalence of ICAM-1+ monocytes and a pro-inflammatory phenotype. Elevated decorin levels may act as a negative regulator of ICAM-1 expression in monocytes. Therefore, perlecan and decorin may be related to inflammation and monocyte activation in CKD and may act as potential markers of endothelial damage.

New mechanisms involved in the development of cardiovascular disease in chronic kidney disease

Chronic kidney disease (CKD) is a pathology with a high worldwide incidence and an upward trend affecting the elderly. When CKD is very advanced, the use of renal replacement therapies is required to prolong its life (dialysis or kidney transplantation). Although dialysis improves many complications of CKD, the disease does not reverse completely. These patients present an increase in oxidative stress, chronic inflammation and the release of extracellular vesicles (EVs), which cause endothelial damage and the development of different cardiovascular diseases (CVD). CKD patients develop premature diseases associated with advanced age, such as CVD. EVs play an essential role in developing CVD in patients with CKD since their number increases in plasma and their content is modified. The EVs of patients with CKD cause endothelial dysfunction, senescence and vascular calcification. In addition, miRNAs free or transported in EVs together with other components carried in these EVs promote endothelial dysfunction, thrombotic and vascular calcification in CKD, among other effects. This review describes the classic factors and focuses on the role of new mechanisms involved in the development of CVD associated with CKD, emphasizing the role of EVs in the development of cardiovascular pathologies in the context of CKD. Moreover, the review summarized the EVs' role as diagnostic and therapeutic tools, acting on EV release or content to avoid the development of CVD in CKD patients.

Low serum albumin levels and in-hospital outcomes in patients with ST segment elevation myocardial infarction

BACKGROUND AND AIMS

Low serum albumin (SA) is associated with an increased risk of long-term adverse events (AEs) among patients with chronic coronary syndromes. Its prognostic role in patients with ST-elevation myocardial infarction (STEMI) is less clear. To investigate the association between low SA and in-hospital AEs in STEMI patients.

METHODS AND RESULTS

Multicenter retrospective cohort study of 220 STEMI patients undergoing primary percutaneous coronary intervention within 12 h from the onset of symptoms. Hypoalbuminemia was defined by serum SA <35 g/L. SA. In-hospital AEs were defined as cardiogenic shock, resuscitated cardiac arrest and death. Median SA was 38 (IQR 35.4-41.0) g/L and 37 (16.8%) patients showed hypoalbuminemia (<35 g/L) on admission. Patients with hypoalbuminemia were older, more frequently women and diabetics, prior CAD and HF. Furthermore, they showed lower hemoglobin levels and impaired renal function. At multivariable logistic regression analysis, diabetes (odds ratio [OR]:4.59, 95% confidence interval [CI] 1.71-12.28, p = 0.002) and haemoglobin (OR:0.52, 95%CI 0.37-0.72, p < 0.001) were associated with low SA. In a subgroup of 132 patients, SA inversely correlated with D-Dimer (rS -0.308, p < 0.001). Globally, twenty-eight (14.6%) AEs were recorded. Hypoalbuminemia (OR:3.43, 95%CI 1.30-9.07, p = 0.013), high-sensitive (HS)-Troponin peak above median (OR:5.41, 95%CI 1.99-14.7, p = 0.001), C-reactive protein (CRP) peak above median (OR:6.03, 95%CI 2.02-18.00, p = 0.001), and in-hospital infection (OR:3.61, 95%CI 1.21-10.80, p = 0.022) were associated with AEs.

CONCLUSION

Low SA levels are associated with worse in-hospital AEs in STEMI patients, irrespective of HS-troponin and CRP plasma levels. Our findings suggest that low SA may contribute to the pro-thrombotic phenotype of these patients.

Premature Aging in Chronic Kidney Disease: The Outcome of Persistent Inflammation beyond the Bounds

Over the last hundred years, life expectancy in developed countries has increased because of healthier living habits and the treatment of chronic pathologies causing premature aging. Aging is an inexorable, time-dependent, multifactorial process characterized by a series of progressive and irreversible physiological changes associated with loss of functional, psychological, and social capabilities. Numerous factors, such as oxidative stress, inflammation, and cellular senescence, and an irreversible geriatric syndrome known as frailty, contribute to human body deterioration in aging. The speed of aging may differ between individuals depending on the presence or absence of multiple factors (genetic and/or environment) and the subsequent misbalance of homeostasis, together with the increase of frailty, which also plays a key role in developing chronic diseases. In addition, pathological circumstances have been reported to precipitate or accelerate the aging process. This review investigated the mechanisms involved in the developing pathologies, particularly chronic kidney disease, associated with aging.

Immune Dysfunction in Dialysis Patients—Prevention and Treatment Strategies

Immune dysfunction, resulting in infection or inflammation, or both, is closely associated with poor clinical outcome in end-stage renal disease patients. So far, no single measure can effectively address this condition, because many factors, such as uremia per se and dialysis treatment are involved in the pathogenesis. Our review focuses on currently available treatments and prevention options, and identifies future research needs.

Nephrotoxic effects caused by co-exposure to noise and toluene in New Zealand white rabbits: A biochemical and histopathological study

The biological and renal effects made by simultaneous and non-simultaneous exposure to toluene and noise were investigated. Twenty-four New Zealand white rabbits were exposed to 100 dB of white noise and 1000 ppm of toluene vapor for two weeks. The examined biochemical factors were urea, uric acid, creatinine, glucose, triglyceride, cholesterol, and albumin serum levels, measured on different days after the end of the exposure. Moreover, glutathione peroxidase activity (GPX), malondialdehyde dismutase activity (MDA), and superoxide dismutase (SOD) parameters were measured in the kidney tissue. The hematoxylin and eosin staining method was used for histopathological experiments. Overall, the noise increased albumin, uric acid, creatinine, and glucose levels, but it decreased urea, cholesterol, and triglyceride levels. Toluene decreased albumin, uric acid, and urea levels, while it increased creatinine, triglyceride, cholesterol, and glucose levels. Simultaneous exposure to noise and toluene decreased albumin, uric acid, cholesterol, and urea levels, whereas it increased creatinine, glucose, and triglyceride levels. GPX, MDA, and SOD levels increased by simultaneous and non-simultaneous exposure to noise and toluene. Furthermore, massive tubular degeneration, tubular cell vacuolization, glomerular disorganization, congestion, glomerular cell shrinkage, and unclear brush border were detected in the kidney tissue.

Oral supplementation with omega-3 fatty acids and inflammation markers in patients with chronic kidney disease in hemodialysis

Chronic kidney disease (CKD) is an increasingly common public health problem that increases the risk of death because of cardiovascular complications by 2-3 times compared with the general population. This research concerns a prospective, randomized, double-blind study in patients with CKD undergoing hemodialysis. The participants were assigned to 1 of 2 groups: the study group (group A; 46 patients) received 4 capsules (2.4 g) of omega-3 fatty acids daily during the 12-week intervention, while patients in the control group (group B; 47 patients) received 4 capsules of paraffin oil. The patients' general characteristics, nutritional indicators, renal disease markers and inflammatory markers (C-reactive protein, interleukin (IL)-6, IL-10, and tumour necrosis factor alpha (TNF-α)) were evaluated. No differences were found between the general characteristics of the patients (P < 0.05), and no differences were shown in the nutritional indicators and markers of kidney disease (P < 0.05). Patients in group A showed significant decreases in levels of C-reactive protein, IL-6, TNF-α, and the IL-10/IL-6 ratio after 12 weeks of supplementation (P < 0.05). Patients in group B did not show any significant changes in concentrations of inflammatory markers during the intervention (P < 0.05). In conclusion, oral supplementation with omega-3 fatty acids produces a significant decrease in the concentrations of inflammation markers in patients with chronic kidney disease on hemodialysis. Novelty Oral supplementation with omega-3 fatty acids produced significant decreases in the concentrations of inflammation markers. This supplementation could be given to patients with uremic syndrome and coronary heart disease to reduce cardiovascular risk.

Seroprevalence of a "new" bacterium, Simkania negevensis, in renal transplant recipients and in hemodialysis patients

Background

Simkania negevensis is an obligate intracellular bacterium belonging to the family Simkaniaceae in the Chlamydiales order. It is considered an ubiquitous microorganism and aquatic environments may be involved as a source of infection for humans. It was just isolated in samples from domestic water supplies and from mains water supplies, like spa water or swimming pool water, confirming its ability to resist to the common chlorination treatments. Evidence indicates a possible role of the microorganism in respiratory tract infections, in gastroenteric disorders and in the pathogenesis of cardiovascular disease, furthermore it has hypothesized that it could play a role in lung transplant rejection. Prevalence and possible effects in nephrology are unknown.

Methods

We examined the occurrence of Simkania negevensis in two differents populations, both characterized by a high susceptibility to infectious complications: 105 hemodialysis patients, 105 renal transplant recipients and 105 healthy subjects through the IgG and IgA response to Simkania negevensis in their sera. Serum antibodies to Simkania negevensis were detected by a homemade ELISA performed according to the Kahane’s protocol. Furthermore water samples from hemodialytic circuit were collected, to evaluate Simkania negevensis resistance to usual treatment of disinfection.

Results

Our results were unexpected, showing a higher seroprevalence of antibodies against Simkania negevensis in the hemodialysis patients, compared to renal transplant patients (IgG 22% vs 9% - IgA 9% vs 3%). S. negevensis was isolated in all water samples analyzed.

Conclusions

Our study detected for the first time the occurrence of S. negevensis in hemodialysis and in renal transplant patients. Our findings suggest that water used in hemodialysis could be one of the possible sources of S. negevensis infection, without clinical involvement risk for patients.

Impact of arteriovenous fistula blood flow on serum il-6, cardiovascular events and death: An ambispective cohort analysis of 64 Chinese hemodialysis patients

Flows (Qa) of arteriovenous fistula (AVF) impact the dialysis adequacy in hemodialysis (HD) patients. However, data for different access flow levels on outcomes related to long-term dialysis patients, especially in Chinese patients, are limited. Herein, we performed an ambispective, mono-centric cohort study investigating the association between the AVF flows and inflammation, cardiovascular events and deaths in Chinese hemodialysis patients bearing a radio-cephalic fistula (AVF) from 2009 to 2015. Twenty-three patients (35.9%) developed at least one episode of cardiovascular disease (CVD) in two years after AVF creation. AVF Qa, IL-6 and hsCRP were significantly higher in patients with CVD than in patients without CVD. Multi-factorial binary logistic regression analysis found that the independent and strongest risk factor for CVD in HD patients was serum IL-6, which showed a positive association with AVF Qa levels in patients. Therefore, the linkage between AVF Qa tertiles and adverse clinical outcomes (cardiovascular events and mortality) was examined over a median follow-up of five years. IL-6 was significantly increased in the high AVF Qa (>1027.13 ml/min) group. Patients with median AVF Qa showed the lowest morbidity and mortality of CVD according to the AVF Qa tertiles, whereas higher Qa was associated with a higher risk of CVD, and lower AVF Qa (600 ml/min ≤AVF Qa <821.12 ml/min) had a higher risk of non-CVD death. Therefore, keeping the AVF Qa at an optimal level (821.12 to 1027.13 ml/min) would benefit HD patients, improve long-term clinical outcomes and lower AVF-induced inflammation.

The prevalence of renal impairment in individuals seeking HIV testing in Urban Malawi

BACKGROUND

Chronic kidney disease (CKD) poses a major health threat to people living in low- and middle-income countries, especially when it is combined with HIV, antiretroviral treatment (ART) or communicable and non-communicable diseases. Data about the prevalence of CKD and its association with other diseases is scarce, particularly in HIV-negative individuals. This study estimated the prevalence of CKD in individuals who were either HIV-positive (and ART-naïve) or HIV-negative in an urban Malawian population.

METHODS

This cross-sectional study was conducted at a HIV Testing and Counselling Centre in Lilongwe, Malawi. Consecutive clients who were ≥18 years and consented to participate were enrolled over a 3-month period. Clients were screened for potential renal disease and other conditions. Their blood pressure was measured, urine examined via dipstick and albumin/creatinine ratio and blood drawn for creatinine, cystatin C and sero-markers for schistosomiasis. Estimated glomerular filtration (eGFR) rate was calculated using a cystatin C-based formula and classified according to the matching CKD stages by K/DOQI (The National Kidney Foundation Kidney Disease Outcome Quality Initiative). We performed a descriptive analysis and compared differences between HIV-positive (and ART naïve) and -negative participants.

RESULTS

Out of 381 consecutive clients who were approached between January and March 2012, 366 consented and 363 (48% female; 32% HIV-positive) were included in the analysis. Reasons for exclusion were missing samples or previous use of ART. HIV-positive and negative clients did not differ significantly with regard to age, sex or medical history, but they did differ for BMI-21.3 (±3.4) vs. 24 (±5.1), respectively (p < 0.001). Participants also differed with regard to serum cystatin C levels, but not creatinine. Reduced kidney function (according to CKD stages 2-5) was significantly more frequent 15.5 vs. 3.6%, respectively (p < 0.001) among HIV-positive clients compared to the HIV-negative group. Differences in renal function were most pronounced in the eGFR range 60-89 ml/min/1.73 m2 accompanied by proteinuria with results as 11.2% vs. 1.2%, respectively for clients who were HIV-positive vs. HIV-negative (p = 0.001).

CONCLUSIONS

Reduced glomerular filtration and/or proteinuria occurred in 15.5% of HIV-positive, and 3.6% of HIV-negative patients in this urban Malawian cohort. Since generalized renal monitoring is not feasible in Malawi or other resource-limited countries, strategies to identify patients at risk for higher stages of CKD and appropriate preventive measures are needed for both HIV-positive and HIV-negative patients.

sTREM-1 in patients with chronic kidney disease on hemodialysis

The triggering receptor expressed on myeloid cells-1 (TREM-1) is a member of the immunoglobulin superfamily. TREM-1 has been implicated as an amplifier of inflammation. Soluble TREM-1 (sTREM-1) was investigated in different clinical conditions, but not in hemodialysis (HD) patients. We aimed to investigate sTREM-1 as a marker of inflammation in HD patients. We investigated 40 CKD patients undergoing chronic HD treatment and 15 controls. Routine laboratory investigations in addition to CRP measured by immunoturbidimetry, TNF- α, and sTREM-1 measured by ELISA were assayed in post-hemodialysis patients' blood samples and in controls' blood samples. CRP, TNF-α, and sTREM-1 levels were significantly higher in HD patients than in controls (p < 0.001 for all). sTREM-1 was positively correlated with CRP and TNF-α (r = +0.50, p < 0.001 and r = +0.53, p < 0.001 respectively). It was negatively correlated with hemoglobin concentration (r = -0.69, p < 0.001). Hemoglobin concentration was the significant predictor of sTREM-1 level (p < 0.001). In conclusion, sTREM-1 level is significantly increased in HD patients as are other pro-inflammatory markers.

Hemodialysis Is Associated With Increased Peripheral Artery Occlusive Disease Risk Among Patients With End-Stage Renal Disease: A Nationwide Population-Based Cohort Study

To investigate the effect of different dialysis modalities on the incidence of peripheral artery occlusive disease (PAOD) among patients with end-stage renal disease (ESRD) in a large population-based cohort study. The cohort study included 26,927 ESRD patients who underwent hemodialysis (17,737 patients, hemodialysis [HD] cohort) or peritoneal dialysis (PD, 9190 patients, PD cohort), and 107,588 matched controls between 2000 and 2010. A Cox proportional hazards model was to evaluate the risk of PAOD in the ESRD underwent HD or PD. Based on a mean follow-up period of 2.92, 3.64, and 4.91 years in the PD, HD, and control cohorts, respectively, the incidences of PAOD were 18.1% and 8.10% higher in the HD and PD cohorts, respectively, compared with the control cohort (log-rank test P < 0.001). The patients who underwent HD or PD exhibited a higher risk of PAOD compared with the control cohort regardless of age, sex, and presence or absence of comorbidities. In addition, the incidence of PAOD in the PD cohort and the propensity score-matched HD cohort were 12.4 and 20.7 per 1000 person-years, respectively, with a hazard ratio of 1.92 (95% confidence interval = 1.62-2.28) in HD patients, compared with the PD cohort. This nationwide population-based cohort study suggested a significantly increased risk of PAOD among ESRD patients. Moreover, the PD patients have a lower risk of developing PAOD compared with the HD cohort, indicating the beneficial roles of PD in reducing PAOD risk in ESRD patients.

Variability in estimated glomerular filtration rate by area under the curve predicts renal outcomes in chronic kidney disease

Greater variability in renal function is associated with mortality in patients with chronic kidney disease (CKD). However, few studies have demonstrated the predictive value of renal function variability in relation to renal outcomes. This study investigates the predictive ability of different methods of determining estimated glomerular filtration rate (eGFR) variability for progression to renal replacement therapy (RRT) in CKD patients. This was a prospective observational study, which enrolled 1,862 CKD patients. The renal end point was defined as commencement of RRT. The variability in eGFR was measured by the area under the eGFR curve (AUC)%. A significant improvement in model prediction was based on the -2 log likelihood ratio statistic. During a median 28.7-month follow-up, there were 564 (30.3%) patients receiving RRT. In an adjusted Cox model, a smaller initial eGFR AUC%_12M (P < 0.001), a smaller peak eGFR AUC%_12M (P < 0.001), and a larger negative eGFR slope_12M (P < 0.001) were associated with a higher risk of renal end point. Two calculated formulas: initial eGFR AUC%_12M and eGFR slope_12M were the best predictors. Our results demonstrate that the greater eGFR variability by AUC% is associated with the higher risk of progression to RRT.

Correlation between the microinflammatory state and left ventricular structural and functional changes in maintenance haemodialysis patients

The aim of this study was to examine the correlation between the microinflammatory state and structural and functional changes of the left ventricle in maintenance haemodialysis patients (MHD). In total, 48 MHD patients and 30 healthy volunteers participated in this study. The microinflammatory state was detected from high-sensitivity C-reactive protein (hs-CRP), interleukin-6 (IL-6) and tumour necrosis factor-α (TNF-α) levels determined by ELISA. The structure and function of the left ventricle was measured according to ultrasound cardiogram examination. The serum levels of hs-CRP, IL-6 and TNF-α in the MHD patients were higher compared with those in the controls (P<0.05). Furthermore, the measurements of the left atrial diameter (LAD), left venticular diameter (LVD), interventricular septal thickness (IVST), left ventricular posterior wall thickness (LVPWT) and the left ventricular mass index (LVMI) increased significantly and the left ventricular function (LVEF) was reduced. Correlation analysis demonstrated that the concentrations of hs-CRP, TNF-α and IL-6 correlated with the LVMI (P<0.05), but only hs-CRP correlated with the loss of function of the heart in the haemodialysis patients (P<0.05). The microinflammatory state may be closely associated with the structural and functional impairment of the heart in MHD patients.

Inflammatory status in chronic renal failure: The role of homocysteinemia and pro-inflammatory cytokines

AIM: To evaluate determinants of inflammatory markers in chronic renal failure patients according to the level of glomerular filtration rate.

METHODS: One hundred fifty four patients (Age: 44 ± 06 years; male/female: 66/88) with chronic renal failure (CRF) were divided into 6 groups according to the National Kidney Foundation (NKF) classification. They included 28 primary stage renal failure patients (CRF 1), 28 moderate stage renal failure patients (CRF 2), 28 severe stage renal failure patients (CRF 3), 18 end-stage renal failure patients (CRF 4), 40 hemodialysis (HD) patients, and 12 peritoneal dialysis (PD) patients. Tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6) and C-reactive protein (CRP) were analyzed by immunosorbent assay kit (ELISA) (Cayman Chemical’s ACETM EIA kit). Immunoassay methods were used for total homocysteine (tHcy) (fluorescence polarization immunoanalysis HPLC, PerkinEmer 200 series), transferrin (MININEPHTM human transferin kit: ZK070.R), ferritin (ADVIA Centaur) and fibrinogen analysis (ACL 200). Differences between groups were performed using SPSS 20.0 and data are expressed as the mean ± SD.

RESULTS: Results showed that in comparison with CRF 1 group and other groups, TNF-α and IL-6 levels were respectively more elevated in HD (16.38 ± 5.52 pg/mL vs 0.39 ± 0.03 pg/mL, 11.05 ± 3.59 pg/mL vs 8.20 ± 0.22 pg/mL, P < 0.001) and PD (14.04 ± 3.40 pg/mL vs 0.39 ± 0.03 pg/mL, 10.15 ± 1.66 pg/mL vs 8.20 ± 0.22 pg/mL, P < 0.001). IL-1β levels were increased in HD (9.63 ± 3.50 pg/mL vs 3.24 ± 0.10 pg/mL, P < 0.001) and CRF 4 (7.76 ± 0.66 pg/mL vs 3.24 ± 0.10 pg/mL, P < 0.001) patients than in CRF 1 and in the other groups. Plasma tHcy levels were higher in HD (32.27 ± 12.08 μmol/L) and PD (28.37 ± 4.98 μmol/L) patients compared to the other groups of CRF (P < 0.001). The serum CRP level was significantly increased in HD (18.17 ± 6.38 mg/L) and PD (17.97 ± 4.85 mg/L) patients compared to the other groups of CRF patients (P < 0.001). The plasma fibrinogen level was more elevated in HD (6.86 ± 1.06 g/L) and CRF 4 (6.05 ± 0.57 g/L) than in the other groups (P < 0.001). Furthermore; the ferritin level was higher in HD (169.90 ± 62.16 ng/mL) and PD (90.08 ± 22.09 ng/mL) patients compared to the other groups of CRF (P < 0.001). The serum transferrin value was significantly decreased especially in PD (1.78 ± 0.21 g/L) compared to the other groups (P < 0.001). We found a negative correlation between glomerular filtration rate (GFR), TNF-α levels (r = -0.75, P < 0.001), and tHcy levels (r = -0.68, P < 0.001). We observed a positive correlation between GFR and transferrin levels (r = 0.60, P < 0.001).

CONCLUSION: CRF was associated with elevated inflammatory markers. The inflammation was observed at the severe stage of CRF and increases with progression of renal failure.

Psychosocial factors in adults with chronic kidney disease: characteristics of pilot participants in the Tasmanian Chronic Kidney Disease study

BACKGROUND

Psychosocial factors including depression, anxiety and lower social support are common in patients with chronic kidney disease (CKD). However the influence of these potentially modifiable risk factors on morbidity and mortality in this renal population is unknown. The Tasmanian Chronic Kidney Disease study is a prospective cohort study which aims to examine the influence of both biomedical and psychosocial factors on disease progression, decision making and length and quality of life in adults with severe CKD, prior to kidney replacement therapy (KRT). This paper describes the recruitment, baseline characteristics and initial follow-up of pilot participants.

METHODS

Adults aged > 18 years with stage 4 CKD (eGFR 15-29 mls/min/1.73 m2) and not receiving dialysis were recruited via treating physicians. Measures included depression (9-item Patient Health Questionnaire), anxiety (Beck Anxiety Inventory) and social support (Multidimensional Scale of Perceived Social Support). Primary outcomes were kidney disease progression, use of KRT and health-related quality of life (Kidney Disease and Quality of Life Short Form and the EQ-5D).

RESULTS

Of those invited (n = 105), 49 provided consent and completed baseline assessment. There were no significant differences between responders and non-responders in age, gender and socio-economic status (all p > 0.05). Participants were predominantly male (63.3%) with a mean age of 72.6 ± 10.2 years. Mean serum creatinine was 241 ± 62 μmol/L with mean eGFR 22 ± 5 mls/min/1.73 m2. Prevalence of major depression and moderate to severe anxiety was 10% and 9% respectively. Less severe depression and fewer anxiety symptoms were associated with higher health-related quality of life. Follow-up at 10-months showed CKD progression in 34% of participants (use of KRT in 16%, stage 5 CKD without KRT in 18%), one death, with the remainder stable at CKD stage 3 or 4.

CONCLUSIONS

Results indicate that a larger prospective study is feasible and has the capacity to examine the influence of biomedical and psychosocial factors on kidney disease progression, use of dialysis and transplantation, and salient personal and economic outcomes. Findings have the potential to provide an evidence base for revising healthcare provision in order to optimize the care of patients with CKD.

Cytokines: monitors of disease severity for the clinic

BACKGROUND

Cytokines communicate between the cells of the immune system and its targets to maintain homeostasis after injury or pathogenic events. They are involved in almost any pathological situation imaginable.

OBJECTIVE

To verify the importance of cytokines as biomarkers in current preclinical (aetiopathogenic, development of new therapies) and clinical studies (diagnosis, disease severity, prognosis and response to therapy).

METHOD/RESULTS

A Medline search with the query 'cytokine' AND 'biomarker' AND a variable for a variety of biomedical fields, followed by deeper-level searches, demonstrated the immense popularity of cytokines as biomarkers in almost any biomedical field.

CONCLUSION

As cytokines are not disease-specific they do not serve as single diagnostic biomarkers. The strength of the cytokines resides in monitoring disease severity, prognosis and response to treatment.

The relationship between psychological factors, inflammation, and nutrition in patients with chronic renal failure undergoing hemodialysis

OBJECTIVE

Hemodialysis has an adverse impact on the immunological, nutritional, and emotional status of patients. The biochemical markers of inflammation and nutrition were studied as well as the relationship of these factors to emotional symptoms.

METHOD

One hundred and ninety-five patients undergoing hemodialysis were enrolled. The mean age was 58.5 years. Emotional symptoms were assessed using the Mini International Neuropsychiatric Interview, Hospital Anxiety and Depression Scale, Chalder Fatigue Scale, and Short-form Health-related Quality of Life. Venus blood was collected for laboratory assessment of serum hemoglobin, albumin, ferritin, C-reactive protein, interleukin (IL) 1beta), IL-6, and tumor necrosis factor alpha.

RESULTS

Among the 195 subjects (92 men and 103 women), 47 (24.1%) fulfilled the criteria for a major depressive disorder (MDD). The IL-6 level in patients with a MDD was significantly higher than in the patients without a MDD. Significant correlation was observed among the following factors: IL-6, fatigue, and quality of life for both physical and mental components. The albumin levels showed a significant correlation with the IL-6 and depression scores.

CONCLUSIONS

These results show that the serum levels of albumin and IL-6 might be laboratory markers associated with the expression of emotional symptoms in patients undergoing hemodialysis. Prospective studies are needed to determine the causal relationships among these variables.

High-flux versus low-flux membranes for end-stage kidney disease

BACKGROUND

Clinical practice guidelines regarding the use of high-flux haemodialysis membranes vary widely.

OBJECTIVES

We aimed to analyse the current evidence reported for the benefits and harms of high-flux and low-flux haemodialysis.

SEARCH METHODS

We searched Cochrane Renal Group's specialised register (July 2012), the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (1948 to March 2011), and EMBASE (1947 to March 2011) without language restriction.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that compared high-flux haemodialysis with low-flux haemodialysis in people with end-stage kidney disease (ESKD) who required long-term haemodialysis.

DATA COLLECTION AND ANALYSIS

Data were extracted independently by two authors for study characteristics (participants and interventions), risks of bias, and outcomes (all-cause mortality and cause-specific mortality, hospitalisation, health-related quality of life, carpal tunnel syndrome, dialysis-related arthropathy, kidney function, and symptoms) among people on haemodialysis. Treatment effects were expressed as a risk ratio (RR) or mean difference (MD), with 95% confidence intervals (CI) using the random-effects model.

MAIN RESULTS

We included 33 studies that involved 3820 participants with ESKD. High-flux membranes reduced cardiovascular mortality (5 studies, 2612 participants: RR 0.83, 95% CI 0.70 to 0.99) but not all-cause mortality (10 studies, 2915 participants: RR 0.95, 95% CI 0.87 to 1.04) or infection-related mortality (3 studies, 2547 participants: RR 0.91, 95% CI 0.71 to 1.14). In absolute terms, high-flux membranes may prevent three cardiovascular deaths in 100 people treated with haemodialysis for two years. While high-flux membranes reduced predialysis beta-2 microglobulin levels (MD -12.17 mg/L, 95% CI -15.83 to -8.51 mg/L), insufficient data were available to reliably estimate the effects of membrane flux on hospitalisation, carpal tunnel syndrome, or amyloid-related arthropathy. Evidence for effects of high-flux membranes was limited by selective reporting in a few studies. Insufficient numbers of studies limited our ability to conduct subgroup analyses for membrane type, biocompatibility, or reuse. In general, the risk of bias was either high or unclear in the majority of studies.

AUTHORS' CONCLUSIONS

High-flux haemodialysis may reduce cardiovascular mortality in people requiring haemodialysis by about 15%. A large well-designed RCT is now required to confirm this finding.

Vitamin D and racial disparity in albuminuria: NHANES 2001-2006

Background

National data show unexplained racial disparity in albuminuria. We assessed whether low serum vitamin D status contributes to racial disparity in albuminuria.

Methods

We examined the association between race and albuminuria (spot urinary albumin/creatinine ratio (ACR) ≥30) among non-Hispanic black and white nonpregnant adults who were free of renal impairment in the National Health and Nutrition Examination Survey (NHANES) from 2001–2006. We conducted analyses without and with serum 25(OH)D. We adjusted for age, sex, education level, smoking, body mass index (BMI), diabetes, diagnosis of hypertension, and use of antihypertensive medication.

Results

Albuminuria was present in 10.0% of non-Hispanic blacks and 6.6% in non-Hispanic whites. Being black (odds ratio (OR) 1.46; 95% confidence interval (CI) 1.23–1.73) was independently associated with albuminuria. There was a graded, inverse association between 25(OH)D level and albuminuria. Notably, the association between race and albuminuria was no longer significant (OR 1.19; 95% CI 0.97–1.47) after accounting for participants' serum 25(OH)D. Similar results were observed when participants with macroalbuminuria (ACR ≥300 mg/g) or elevated parathyroid hormone (>74 pg/ml) were excluded or when a continuous measure of 25(OH)D was substituted for the categorical measure. There were no interactions between race and vitamin D status though racial disparity in albuminuria was observed among participants with the highest 25(OH)D levels.

Conclusion

Suboptimal vitamin D status may contribute to racial disparity in albuminuria. Randomized controlled trials are needed to determine whether supplementation with vitamin analogues reduces risk for albuminuria or reduce racial disparity in this outcome.

Impact of the duration of posttransplant renal replacement therapy on bacterial infections in liver transplant recipients

Whether the duration of renal replacement therapy (RRT) after liver transplantation influences the rate and types of bacterial infections is not known. In this study, 47 of 299 consecutive liver transplant recipients (16%) required posttransplant RRT. The incidence of bacterial infections was higher in the RRT group versus the non-RRT group (8.84 versus 1.38 per 1000 patient days, P < 0.001). In the RRT group, 49% of the patients (23/47) required long-term RRT (≥30 days), and 51% (24/47) required short-term RRT (<30 days). Long-term RRT (hazard ratio = 2.27, 95% confidence interval = 1.16-4.47, P = 0.017) was a significant predictor of infections. Bacteremia and intra-abdominal infections were the most common sources of infections, and Enterobacteriaceae and enterococci were the predominant pathogens in both groups. The mortality rate for patients requiring RRT was higher than the rate for patients not requiring RRT (P < 0.001), but the mortality rates of the short-term RRT group and the long-term RRT group did not significantly differ (P = 0.654). In conclusion, although both short-term RRT and long-term RRT confer a higher risk of bacterial infections, only long-term RRT is a statistically significant predictor of these infections.

The Interrelationships among albumin, nutrient intake, and inflammation in elderly recuperative care patients

OBJECTIVES

To examine the interrelationships among low serum albumin, nutritional depletion, and ongoing inflammation in older patients recovering from illness.

DESIGN

A prospective cohort study.

SETTING

A transitional care unit (TCU) within a Department of Veterans Affairs hospital nursing home care unit.

PARTICIPANTS

275 older veterans (mean age=78.9 ± 7.5y, 99% male) admitted for recuperative care and rehabilitation.

MEASUREMENTS

At admission and discharge (median LOS 24d, IQR 16 to 44d), each subject completed a comprehensive standardized evaluation including a nutritional assessment and measurement of serum albumin, C-reactive protein (CRP), interleukin-6 (IL-6) and its soluble receptor, and tumor necrosis factor-alpha (TNF-α) and its soluble receptors (sTNF-RI and II). Complete nutrient intake assessments (calorie counts) were performed daily.

RESULTS

Both the discharge albumin and the change in albumin (discharge minus admission) were strongly and inversely correlated with various indicators of inflammation, particularly CRP and IL-6. Change in CRP was the strongest correlate of change in albumin (R2 = 0.21, P<.001) and discharge IL-6 the strongest correlate of discharge albumin (R2 = 0.21, P<.001). Nutrient intake also correlated with albumin and its change, but entered the multivariable models after inflammatory indicators and explained a smaller portion of the variance. Although there were significant interactions between time and both nutrient intake and inflammation, the relative importance of inflammation as a potential determinant of the serum albumin concentration appeared to remain unchanged with longer periods of observation.

CONCLUSIONS

Among elderly patients admitted to a TCU, inflammation appears to be a more powerful determinant of albumin and its change during the hospitalization than is nutrient intake. Further study is needed to prove causality and to determine whether the relative importance of inflammation on the albumin concentration diminishes with more prolonged periods of observation.

Interleukin-6 and silent cerebral infarction in hemodialysis patients: a cross-sectional study

BACKGROUND

In patients with chronic renal failure undergoing hemodialysis (HD), silent cerebral infarctions (SCI) are associated with high mortality. Levels of interleukin-6 (IL-6) increase with renal dysfunction and may be a novel predictor for cerebrovascular events. We tested the hypothesis that increased IL-6 levels correlate with the occurrence of SCI in HD patients.

METHODS

Using cranial magnetic resonance imaging findings, we divided 50 Japanese patients undergoing HD into two groups: with SCI (60 ± 7 years, mean ± SD, n = 27) and without SCI (60 ± 6 years, n = 23). We compared the gender, body mass index, metabolic profiles, IL-6 levels, and smoking habits between the two groups.

RESULTS

We made the following observations: (i) The prevalence of diabetes or hypertension did not differ between the two groups, (ii) the level of IL-6 was higher in the with-SCI group than in the without-SCI group (P < 0.0001), (iii) the proportion of smokers was higher in the with-SCI group (P < 0.05), (iv) plasma level of high-density lipoprotein cholesterol was lower, whilst uric acid level was higher, in the with-SCI group (P < 0.05 and P < 0.05, respectively), and (v) multiple logistic regression analysis identified IL-6 levels as being significantly associated with the presence of SCI (odds ratio 3.13, 95% CI = 1.42-7.89, P < 0.0001).

CONCLUSIONS

This study indicates that patients with chronic renal failure who are maintained on HD exhibit an increased prevalence of SCI and that IL-6 is significantly associated with the presence of SCI in HD patients.

A translational approach to micro-inflammation in end-stage renal disease: molecular effects of low levels of interleukin-6

Inflammation plays a key role in the progression of cardiovascular disease, the leading cause of mortality in ESRD (end-stage renal disease). Over recent years, inflammation has been greatly reduced with treatment, but mortality remains high. The aim of the present study was to assess whether low (<2 pg/ml) circulating levels of IL-6 (interleukin-6) are necessary and sufficient to activate the transcription factor STAT3 (signal transducer and activator of transcription 3) in human hepatocytes, and if this micro-inflammatory state was associated with changes in gene expression of some acute-phase proteins involved in cardiovascular mortality in ESRD. Human hepatocytes were treated for 24 h in the presence and absence of serum fractions from ESRD patients and healthy subjects with different concentrations of IL-6. The specific role of the cytokine was also evaluated by cell experiments with serum containing blocked IL-6. Furthermore, a comparison of the effects of IL-6 from patient serum and rIL-6 (recombinant IL-6) at increasing concentrations was performed. Confocal microscopy and Western blotting demonstrated that STAT3 activation was associated with IL-6 cell-membrane-bound receptor overexpression only in hepatocytes cultured with 1.8 pg/ml serum IL-6. A linear activation of STAT3 and IL-6 receptor expression was also observed after incubation with rIL-6. Treatment of hepatocytes with 1.8 pg/ml serum IL-6 was also associated with a 31.6-fold up-regulation of hepcidin gene expression and a 8.9-fold down-regulation of fetuin-A gene expression. In conclusion, these results demonstrated that low (<2 pg/ml) circulating levels of IL-6, as present in non-inflamed ESRD patients, are sufficient to activate some inflammatory pathways and can differentially regulate hepcidin and fetuin-A gene expression.

Fatigue in patients receiving maintenance dialysis: a review of definitions, measures, and contributing factors

Fatigue is a debilitating symptom or side effect experienced by many patients on long-term dialysis therapy. Fatigue has a considerable effect on patient health-related quality of life and is viewed as being more important than survival by some patients. Renal providers face many challenges when attempting to reduce fatigue in dialysis patients. The lack of a reliable, valid, and sensitive fatigue scale complicates the accurate identification of this symptom. Symptoms of daytime sleepiness and depression overlap with fatigue, making it difficult to target specific therapies. Moreover, many chronic health conditions common in the long-term dialysis population may lead to the development of fatigue and contribute to the day-to-day and diurnal variation in fatigue in patients. Key to improving the assessment and treatment of fatigue is improving our understanding of potential mediators, as well as potential therapies. Cytokines have emerged as an important mediator of fatigue and have been studied extensively in patients with cancer-related fatigue. In addition, although erythropoietin-stimulating agents have been shown to mitigate fatigue, the recent controversy regarding erythropoietin-stimulating agent dosing in patients with chronic kidney disease suggests that erythropoietin-stimulating agent therapy may not serve as the sole therapy to improve fatigue in this population. In conclusion, fatigue is an important and often underrecognized symptom in the dialysis population. Possible interventions for minimizing fatigue in patients on long-term dialysis therapy should aim at improving health care provider awareness, developing improved methods of measurement, understanding the pathogenesis better, and managing known contributing factors.

Novel targets and new potential: developments in the treatment of inflammation in chronic kidney disease

BACKGROUND

Patients with chronic kidney disease (CKD) of all stages experience extremely high mortality, with cardiovascular causes accounting for about half of all their deaths. Traditional risk factors such as hypertension, hypercholesterolemia and diabetes mellitus cannot explain the excessively high cardiovascular mortality in CKD. Chronic inflammation is one of the novel risk factors that appear to contribute to the increased mortality seen in patients with CKD. Therapeutic interventions targeting chronic inflammation in CKD may lead to improved outcomes.

OBJECTIVES

To describe the role of inflammation in CKD and to review anti-inflammatory pharmacologic therapies that could have a role in its therapy.

METHODS

A review of the literature was carried out and expert opinion expressed.

RESULTS/CONCLUSION

Inflammation is a common and significant problem in CKD. There are currently no approved pharmacologic anti-inflammatory therapies in CKD but several agents are being studied in early clinical trials, while others could become viable alternatives in the future.

Uremic pruritus, cytokines, and polymethylmethacrylate artificial kidney

Uremic pruritus is one of the common complications in long-term dialysis patients. Recently, researchers reported that immunohypothesis with high serum level of cytokines could be the cause of uremic pruritus. Polymethylmethacrylate (PMMA) artificial kidney (AK) has been reported to adsorb more serum cytokines than other high-flux AKs. In July 2006, 30 patients with severe uremic pruritus from 300 chronic hemodialysis (HD) patients in a single center entered this prospective study. Their dialyzers were changed to PMMA AK for 4 weeks. The severity of pruritus was evaluated every week using the results of a questionnaire (pruritus score). Laboratory assays including predialysis serum blood urea nitrogen (BUN), creatinine, beta2-microglobulin (beta2M), calcium, phosphate, intact parathyroid hormone (iPTH), total CO(2), ferritin, hematocrit, high-sensitivity C-reactive protein (hsCRP), IL-1beta, IL-2, IL-6, IL-18, tumor necrosis factor-alpha (TNF-alpha), Kt/V, and beta2M clearance were measured before and at the end of 4 weeks of PMMA AK use. PMMA AK was effective in reducing the pruritus score from 23.46 +/- 11.94 to 7.38 +/- 6.42 (P < 0.001). The effect of uremic pruritus relief appeared after 1 week of PMMA AK use. There were no significant differences in the laboratory assay results including predialysis serum BUN, Cr, beta2M, calcium, phosphate, calcium-phosphate product, iPTH, total CO(2), ferritin, hematocrit, hsCRP, IL-1beta, IL-2, IL-6, IL-18, TNF-alpha, Kt/V, and beta2M clearance. The mechanism for the beneficial effect of PMMA AK on uremic pruritus remains to be determined. PMMA AK may be a useful adjuvant therapy in chronic HD patients with severe uremic pruritus.

Evaluation of Tubulointerstitial Lesions' Severity in Patients with Glomerulonephritides: An NMR-Based Metabonomic Study

An 1H NMR-based metabonomic approach was used to investigate the correlation of histopathologically assessed tubulointerstitial lesions with the urinary metabolite profile in 77 patients with glomerulonephritides submitted to renal biopsy. The presence of renal damage was predicted with a sensitivity of 96% and a specificity of 99%. Patients with mild, moderate, and severe tubulointerstitial lesions were progressively differentiated from the healthy individuals in the Orthogonal Signal Correction Partial Least-Squares-Discriminant Analysis (OSC/PLS-DA) models with a statistically significant separation between those with mild and with severe lesions. The onset of the tubulointerstitial lesions is characterized by decreased excretion of citrate, hippurate, glycine, and creatinine, whereas further deterioration is followed by glycosuria, selective aminoaciduria, total depletion of citrate and hippurate, and gradual increase in the excretion of lactate, acetate, and trimethylamine-N-oxide. NMR-based metabonomic urinalysis could contribute to the early evaluation of the severity of the renal damage and possibly to the monitoring of kidney function.

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.

Extracorporeal strategies for the removal of middle molecules

Uremic toxins with a molecular weight of less than 500 Da are classified as small nitrogenous waste products. They are highly water soluble, relatively homogeneous, and have no protein binding. Other uremic retention toxins differ significantly from the small nitrogenous metabolite class in molecular weight, heterogeneity, protein binding, and hydrophobicity. The European Uremic Toxin Work Group subdivided molecules into two categories: protein-bound solutes and middle molecules. Middle molecules were defined as toxins in the molecular weight range of 500-60,000 Da, which exceeds the molecular weight of 2000 Da defined in the original middle molecule hypothesis. Under this new proposed definition, most of these middle molecules are low molecular weight peptides and proteins (LMWPs). This concise review focuses on LMWPs. The metabolism of LMWPs is described, including molecular weight, physical conformation, and charge. Factors influencing dialytic removal of LMWPs such as membrane characteristics, protein-membrane interactions, and solute removal mechanisms, as well as strategies to enhance clearance of these compounds are discussed.

Risk factors for de novo acute cardiac events in patients initiating hemodialysis with no previous cardiac symptom

An initial major adverse cardiac event (MACE) is an important predictor of future cardiovascular events in patients with chronic kidney disease (CKD). We sought to identify factors influencing occurrence of initial MACE in new maintenance hemodialysis patients without previous cardiac symptoms during the predialysis phase of CKD. Among 112 participating patients with no predialysis cardiac history, 57 underwent coronary angiography, whereas the other 55 underwent stress thallium-201 single-photon emission computed tomography within 1 month of beginning hemodialysis to detect asymptomatic coronary artery disease (CAD). In subsequent follow-up for a median of 24 months, subjects experiencing an initial MACE were compared with those who did not have such an event based on several clinical parameters at the end of predialysis phase. Asymptomatic CAD was present in 47 patients (42%), who had a higher cumulative MACE rate, than subjects without CAD (49 vs 3%, P<0.001). Multivariate Cox's regression analysis showed that three variables independently predicted initial MACE: asymptomatic CAD (hazard ratio or HR, 611.31; 95% confidence interval or CI, 14.07-26549.23; P<0.001), diabetes (HR, 20.41; 95% CI, 2.07-200.00; P=0.010), and each 1 mg/l increment in C-reactive protein (CRP) (HR, 1.94; 95% CI, 1.27-2.94; P=0.002). In conclusion, detection of asymptomatic CAD, presence of diabetes, or elevated CRP at the end of the predialysis phase were significantly associated with occurrence of an initial MACE in CKD patients starting hemodialysis who had no CAD symptoms.

Inflammation in end-stage renal disease: the hidden enemy

Cardiovascular disease (CVD) remains the major cause of morbidity and mortality in end-stage renal disease (ESRD) patients. As traditional risk factors cannot alone explain the unacceptable high prevalence and incidence of CVD in this high-risk population, inflammation (interrelated to insulin resistance, oxidative stress, wasting and endothelial dysfunction) has been suggested to be a significant contributor. Indeed, several different inflammatory biomarkers, such as high sensitivity C-reactive protein (hs-CRP), have been shown to independently predict mortality in ESRD patients. As CRP is so strongly associated with vascular disease it has been suggested that this hepatic-derived protein is not only a marker, but also a mediator, of vascular disease. Although in vitro data from studies on endothelial cells, monocytes-macrophages and smooth muscle cells support a direct role for CRP in atherogenesis, data from studies performed in vivo have been controversial. The causes of the highly prevalent state of inflammation in ESRD are multiple, including inflammatory signals associated with the dialysis procedure, decreased renal function, volume overload, comorbidity and intercurrent clinical events. As the prevalence of inflammation varies considerably between continents and races, dietary and/or genetic factors may have an impact on inflammation in ESRD. Elevated CRP in dialysis patients could be evaluated at three different levels: (i) national/regional level; (ii) dialysis unit level; and (iii) individual patient level.

Inflammation, cardiovascular disease and nocturnal hemodialysis

PURPOSE OF REVIEW

There is a growing recognition that uremia is a proinflammatory condition. Chronic uremia-associated inflammation contributes to the pathogenesis of atherosclerosis, anemia and cardiovascular calcification in patients with end-stage renal disease (ESRD). Daily nocturnal hemodialysis (DNHD) is a form of frequent intensive renal replacement therapy that has multiple cardiovascular benefits. Here we will review the emerging data of DNHD on inflammation, coronary calcification and anemia management.

RECENT FINDINGS

Increasing the dose and frequency of dialysis by DNHD has been demonstrated, in both short and long-term studies, to reverse several important risk factors for adverse cardiovascular events in ESRD patients. In addition, there are preliminary data indicating the positive effects of DNHD on inflammatory cytokine profile, rate of coronary calcification progression and enhanced erythropoietin responsiveness.

SUMMARY

Augmentation of dialysis dose by DNHD may positively influence uremia-related inflammation. The role of intensive dialysis as a treatment for chronic inflammation requires further research.

Uremic toxins: a new focus on an old subject

The uremic syndrome is characterized by an accumulation of uremic toxins due to inadequate kidney function. The European Uremic Toxin (EUTox) Work Group has listed 90 compounds considered to be uremic toxins. Sixty-eight have a molecular weight less than 500 Da, 12 exceed 12,000 Da, and 10 have a molecular weight between 500 and 12,000 Da. Twenty-five solutes (28%) are protein bound. The kinetics of urea removal is not representative of other molecules such as protein-bound solutes or the middle molecules, making Kt/V misleading. Clearances of urea, even in well-dialyzed patients, amount to only one-sixth of physiological clearance. In contrast to native kidney function, the removal of uremic toxins in dialysis is achieved by a one-step membrane-based process and is intermittent. The resulting sawtooth plasma concentrations of uremic toxins contrast with the continuous function of native kidneys, which provides constant solute clearances and mass removal rates. Our increasing knowledge of uremic toxins will help guide future treatment strategies to remove them.

Cellulose, modified cellulose and synthetic membranes in the haemodialysis of patients with end-stage renal disease

BACKGROUND

When the kidney fails the blood-borne metabolites of protein breakdown and water cannot be excreted. The principle of haemodialysis is that such substances can be removed when blood is passed over a semipermeable membrane. Natural membrane materials include cellulose or modified cellulose, more recently various synthetic membranes have been developed. Synthetic membranes are regarded as being more "biocompatible" in that they incite less of an immune response than cellulose-based membranes.

OBJECTIVES

To assess the effects of different haemodialysis membrane material in patients with end-stage renal disease (ESRD).

SEARCH STRATEGY

We searched MEDLINE, EMBASE, PreMEDLINE, HealthStar CINAHL, the Cochrane Central Register of Controlled Trials (CENTRAL), Biosis, SIGLE, CRIB, UK National Research Register and reference lists of relevant articles. We contacted biomedical companies, known investigators and handsearched selected journals and conference proceedings. Date of most recent search: June 2004.

SELECTION CRITERIA

All randomised controlled trials (RCTs) or quasi-RCTs comparing different haemodialysis membrane material in patients with ESRD.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed the methodological quality of studies. Data was abstracted onto a standard form by one reviewer and checked by another. Relative Risk (RR) and weighted mean difference (WMD) with 95% confidence intervals (CI)) MAIN RESULTS: Thirty two studies were identified. Pre-dialysis ss(2) microglobulin concentrations were not significantly lower in patients treated with synthetic membranes (WMD -14.67, 95% CI -33.10 to 4.05). When analysed for change in ss(2) microglobulin, a fall was only noted with high-flux membranes. The incidence of amyloid was less in patients who were dialysed for six years with high-flux synthetic membranes (one study, RR 0.03, 95% CI 0.00 to 0.54). There was a significant difference in favour of the synthetic (high-flux) membrane in comparison to cellulose membranes for triglycerides (WMD -0.66; 95% CI -1.18 to -0.14) but not for modified cellulose membranes. Dialysis adequacy measured by Kt/V was marginally higher when cellulose membranes were used (WMD -0.10; 95% CI -0.16 to 0.04), whereas synthetic membranes achieved significantly higher Kt/V values when compared with modified cellulose membranes (WMD 0.20, 95% 0.11 to 0.29) . There were no data on quality of life measures.

AUTHORS' CONCLUSIONS

We found no evidence of benefit when synthetic membranes were compared with cellulose/modified cellulose membranes in terms of reduced mortality no reduction in dialysis-related adverse symptoms. Despite the relatively large number of RCTs undertaken in this area none of the included studies reported any measures of quality of life.

Effects of Short DailyversusConventional Hemodialysis on Left Ventricular Hypertrophy and Inflammatory Markers: A Prospective, Controlled Study

Left ventricular hypertrophy (LVH) and inflammation independently increase risk for death in people who receive hemodialysis. A nonrandomized, controlled trial was conducted of the effect of short daily (6 sessions/wk of 3 h each) or conventional (three sessions/wk of 4 h each) hemodialysis on LVH and inflammatory factors. A total of 26 short daily hemodialysis and 51 matched conventional hemodialysis patients were enrolled, and baseline and 12-mo measures of echocardiographic left ventricular mass index (LVMI), serum C-reactive protein (CRP), serum calcium and phosphorus, and erythropoietin resistance index were collected. Baseline characteristics were similar between groups except that hemoglobin and serum calcium were lower and serum phosphorus was higher in the short daily hemodialysis group. At 12-mo follow-up, short daily hemodialysis patients experienced a 30% decrease in LVMI (154 +/- 33 to 108 +/- 25; P < 0.0001). After adjustment for potential confounders, short daily hemodialysis (beta = -41.63, P = 0.03) and percentage decrease in serum phosphorus (beta = -0.12, P = 0.04) predicted a 12-mo decrease in LVMI. Among short daily hemodialysis patients, there were significant reductions in median CRP levels [1.22 interquartile range (IQR) (0.37 to 3.70) to 0.05 IQR (0.05 to 1.17); P < 0.01] and erythropoietin resistance index [19.5 IQR (8.6 to 37.6) to 10.5 IQR (5.5 to 14.6); P < 0.001]. There were no significant changes in LVMI, CRP, or erythropoietin resistance index in the conventional hemodialysis group. Short daily hemodialysis is associated with improved fluid and phosphorus management and a reduction in LVH and inflammatory factors compared with conventional hemodialysis. Future trials are needed to determine whether short daily hemodialysis can reduce morbidity and mortality in this high-risk population.

Acute and chronic influence of hemodialysis according to the membrane used on phagocytic function of neutrophils and monocytes and pro-inflammatory cytokines production in chronic renal failure patients

This work evaluated the phagocytic capacity of monocytes and neutrophils, and tumor necrosis factor-alpha, interleukin 6, 1 and 8 serum levels in chronic renal failure patients under peritoneal dialysis and hemodialysis treatment, compared with chronic renal failure patients without dialysis treatment and healthy individuals, in order to contribute to a better understanding of the action of these therapies on the evolution of chronic renal failure patients. All patients with chronic renal failure (under dialysis or not) showed decreased phagocytic capacity of neutrophils and monocytes. All those in hemodialysis (cellulose acetate or polysulfone membranes) showed a decreased phagocytic capacity. The phagocytic index for neutrophil was 13 times lower than that of the control group for both membranes, whereas for monocytes, only those using polysulfone membrane showed a significant decrease of 4.9 times in phagocytic capacity. There was an acute stimulation of the phagocytosis by neutrophils after a single session of dialysis with both types of membrane, while only cellulose acetate membrane decreased the phagocytic index of monocytes after the hemodialysis session. Patients using cellulose acetate showed a chronic increase in tumor necrosis factor-alpha serum levels, while those using polysulfone showed a chronic increase in interleukin 6. After a single hemodialysis procedure, no acute effect of the treatment on tumor necrosis factor-alpha and interleukin 6 levels was identified. The decreased phagocytic function of neutrophils and monocytes may account for the high levels of susceptibility of chronic renal failure patients to infections with pyogenic bacteria and tuberculosis. Furthermore, inflammatory activity may occur with both types of membrane studied, suggesting that it will be useful for these patients to evaluate some anti-inflammatory or anti-cytokine therapies against tumor necrosis factor-alpha and interleukin 6, in order to avoid cardiovascular complication.

Kidney insufficiency and nutrient-based modulation of inflammation

PURPOSE OF REVIEW

Patients with chronic kidney disease have a high cardiovascular mortality rate. Despite recent advances in dialysis techniques, over 20% of US dialysis patients die every year. Protein-energy malnutrition and inflammation are common and usually concurrent in chronic kidney disease patients, and have been implicated as the main cause of high mortality. We reviewed the pathophysiology of the malnutrition-inflammation complex syndrome and its potential modulation by dietary and other nutritional interventions in chronic kidney disease patients.

RECENT FINDINGS

The malnutrition-inflammation complex syndrome is a main cause of the atherosclerotic cardiovascular disease epidemic in chronic kidney disease. This may be by virtue of the syndrome's inflammatory components. Malnutrition and inflammation lead to weight loss over time, i.e. cachexia in slow motion, and result in decreased serum cholesterol and homocysteine levels. A 'reverse epidemiology' of cardiovascular risk factors is observed in chronic kidney disease, in that obesity, hypercholesterolemia and hyperhomocysteinemia are paradoxically associated with better survival. Among the possible etiologies of the malnutrition-inflammation complex syndrome, anorexia, low nutrient intake and oxidative stress are theoretically amenable to dietary modulation; however, the bulk of findings are epidemiological.

SUMMARY

There is no consensus as to how to correct the malnutrition-inflammation complex syndrome in chronic kidney disease patients. Because the malnutrition-inflammation complex syndrome is multifactorial, its correction probably requires a battery of simultaneous interventions, rather than one single modality. Clinical trials focusing on the syndrome are currently non-existent and are therefore urgently required to improve poor clinical outcome in chronic kidney disease patients.

Membrane Biocompatibility Does Not Affect Whole Body Protein Metabolism during Dialysis

BACKGROUND

Protein-calorie malnutrition is present in 30-50% of dialysis patients. The lack of biocompatibility of the dialysis membrane, which results in low-grade inflammation, could be responsible for this malnutrition. We investigated whether protein-energy malnutrition could be partly due to incompatibility of the dialyzer during the dialysis session.

METHODS

Five patients were dialyzed during 2 periods of 3 weeks (cross-over) with either a single-use low-flux polysulfone or cellulose triacetate (biocompatible) or a single-use cuprophan (bio-incompatible) membrane. As a measure of whole body protein metabolism, a primed constant infusion of L-[1-(13)C]-valine was used during a 4-hour dialysis session.

RESULTS

Cuprophan was a more powerful activator of the complement system than other membranes. Protein metabolism parameters during both study protocols were not different and resulted in the same protein balance during polysulfone/cellulose triacetate (-15 +/- 3) and cuprophan (-13 +/- 2 micromol/kg/h) dialysis.

CONCLUSION

In stable hemodialysis patients with no apparent complications, protein metabolism during dialysis is not affected by the compatibility of the dialysis membrane.

C-reactive protein and end-stage renal disease

The significance of CRP and inflammation has increased over time, especially in the end-stage renal disease (ESRD) population. From a simple marker it now appears that CRP is an active participant in pro-atherosclerotic phenomenon including local pro-inflammatory and thrombotic events. Studies in the general population indicate the usefulness of CRP in prognostication and in monitoring response to therapy. The clinical usefulness of CRP monitoring in chronic kidney disease (CKD) and especially in ESRD deserves closer study. In the meantime, the utility of CRP measurements for monitoring and treatment is on a case-by-case basis. Management of traditional cardiovascular risk factors should be considered. In the interest of optimizing therapy it is prudent to use biocompatible membranes and ultrapure water. A careful search for infectious processes in dialysis patients is recommended, with special attention to vascular access sites, periodontitis, gastritis, and other potentially chronic or covert infections. ACE-inhibitor use should be maximized in all eligible CKD patients. The data on the use of statins in ESRD have been generally positive but await further validation. Individualized use for selected patients is probably beneficial.

In vivo modulation of soluble "antagonistic" IL-6 receptor synthesis and release in ESRD

Soluble gp130 (sgp130) is a soluble circulating receptor of IL-6 with "antagonistic" biologic activity. It is generated independently by either shedding of the extracellular domain of membrane gp130 or alternative mRNA splicing. This study was addressed to clarify the mechanisms underlying sgp130 synthesis and release in patients who undergo regular dialysis treatment (RDT) using dialytic membranes with different biocompatibility. Two groups of RDT patients were enrolled: 11 patients who were treated with cellulosic membranes (C) and 10 patients who were treated with synthetic membranes (S). Ten healthy subjects constituted the control group. Serum samples and peripheral blood mononuclear cells (PBMC) were harvested in all groups (before dialysis in RDT patients). PBMC were cultured for 24 h in the absence or presence of LPS. The serum levels of sgp130 were significantly higher in C group than in control and S patients (C, 603.1 +/- 89.9; control, 396 +/- 49.5; S, 423.4 +/- 27.7 ng/ml; P < 0.01). PBMC from C patients, in the absence of any mitogenic stimulation, released a significantly greater amount of sgp130 as compared with S and control groups (C, 532.6 +/- 161.2; S, 332.4 +/- 148.6; control, 341.4 +/- 125.4 pg/ml; P < 0.01). The sgp130 release was positively correlated with the release of both IL-6 (r = 0.336, P < 0.05) and sIL-6R receptor (r = 0.324, P < 0.05). A significantly higher gp130 gene expression was also observed in unstimulated PBMC from C patients when compared with control and S groups. It is interesting that the expression of the 85-bp exon characteristic of the alternative splicing mRNA for sgp130 was low in all groups. Finally, confocal microscopy analysis showed an increased expression of gp130 on cell surface in unstimulated PBMC from C patients as compared with control and S groups. Our results demonstrate that in patients on RDT with C membranes, the synthesis and release of sgp130 "antagonistic" receptor is significantly increased. This release is seemingly due to a shedding of membrane-bound gp130 receptor. The increased sgp130 release may partially counteract the inflammatory effects caused by IL-6.