Tissue-advanced glycation end product concentration in dialysis patients

Status and trends in epidemiologic characteristics of diabetic end-stage renal disease: an analysis of the 2021 Korean Renal Data System

Korean Renal Data System (KORDS) is a nationwide end-stage renal disease (ESRD) registry database operated by the Korean Society of Nephrology (KSN). Diabetes mellitus is currently the leading cause of ESRD in Korea; this article provides an update on the trends and characteristics of diabetic ESRD patients. The KORDS Committee of KSN collects data on dialysis centers and patients through an online registry program. Here, we analyzed the status and trends in characteristics of diabetic chronic kidney disease stage 5D (CKD 5D) patients using data from 2001 to 2021. In 2021, the dialysis adequacy of hemodialysis (HD) was lower in diabetic CKD 5D patients than in nondiabetic CKD 5D patients, while that of peritoneal dialysis (PD) was similar. Diabetic CKD 5D patients had a higher proportion of cardiac and vascular diseases and were more frequently admitted to hospitals than nondiabetic CKD 5D patients, and the leading cause of death was cardiac disease. From 2001 to 2020, diabetic CKD 5D patients had a higher mortality rate than nondiabetic CKD 5D patients, but in 2021 this trend was reversed. Diabetic PD patients had the highest mortality rate over 20 years. The mortality rate of diabetic HD patients was higher than that of nondiabetic HD patients until 2019 but became lower starting in 2020. There was a decreasing trend in mortality rate in diabetic CKD 5D patients, but cardiac and vascular diseases were still prevalent in diabetic CKD 5D patients with frequent admissions to hospitals. More specialized care is needed to improve the clinical outcomes of diabetic CKD 5D patients.

Associations of Glucometabolic Indices with Aortic Stiffness in Patients Undergoing Peritoneal Dialysis with and without Diabetes Mellitus

Disruptions in glucose metabolism are frequently observed among patients undergoing peritoneal dialysis (PD) who utilize glucose-containing dialysis solutions. We aimed to investigate the relationship between glucometabolic indices, including fasting glucose, insulin resistance, advanced glycation end products (AGEs), PD-related glucose load, and icodextrin usage, and aortic stiffness in PD patients with and without diabetic mellitus (DM). This study involved 172 PD patients (mean age 58.3 ± 13.5 years), consisting of 110 patients without DM and 62 patients with DM. Aortic stiffness was assessed using the carotid-femoral pulse wave velocity (cfPWV). Impaired fasting glucose was defined as a fasting glucose level ≥ 100 mg/dL. Homeostatic model assessment for insulin resistance (HOMA-IR) scores, serum AGEs, dialysate glucose load, and icodextrin usage were assessed. Patients with DM exhibited the highest cfPWV (9.9 ± 1.9 m/s), followed by those with impaired fasting glucose (9.1 ± 1.4 m/s), whereas patients with normal fasting glucose had the lowest cfPWV (8.3 ± 1.3 m/s), which demonstrated a significant trend. In non-DM patients, impaired fasting glucose (β = 0.52, 95% confidence interval [CI] = 0.01-1.03, p = 0.046), high HOMA-IR (β = 0.60, 95% CI = 0.12-1.08, p = 0.015), and a high PD glucose load (β = 0.58, 95% CI = 0.08-1.08, p = 0.023) were independently associated with increased cfPWV. In contrast, none of the glucometabolic factors contributed to differences in cfPWV in DM patients. In conclusion, among PD patients without DM, impaired fasting glucose, insulin resistance, and PD glucose load were closely associated with aortic stiffness.

Accelerated AGEing: The Impact of Advanced Glycation End Products on the Prognosis of Chronic Kidney Disease

Advanced glycation end products (AGEs) are aging products. In chronic kidney disease (CKD), AGEs accumulate due to the increased production, reduced excretion, and the imbalance between oxidant/antioxidant capacities. CKD is therefore a model of aging. The aim of this review is to summarize the present knowledge of AGEs in CKD onset and progression, also focusing on CKD-related disorders (cardiovascular diseases, sarcopenia, and nutritional imbalance) and CKD mortality. The role of AGEs as etiopathogenetic molecules, as well as potential markers of disease progression and/or therapeutic targets, will be discussed.

Fragmented QRS complex on a 12-lead electrocardiogram predicts cardiovascular and all-cause mortality in dialysis patients

BACKGROUND

Cardiovascular disease (CVD) is the most common cause of mortality in end-stage renal disease (ESRD) patients. Fragmented QRS complex (fQRS) has been reported as a helpful marker in evaluating various cardiovascular pathologies. We aimed to investigate the value of the fQRS complex clinical decision of ESRD patients receiving dialysis.

METHODS

This prospective observational study included 411 patients receiving hemodialysis (HD) or continuous ambulatory peritoneal dialysis (CAPD) between 2016-01-01 and 2020-12-31. The primary outcomes were all-cause and cardiovascular (CV) mortality.

RESULTS

HD patients have elevated values of fQRS complex compared to CAPD patients (39.1% vs. 28.2%, P = 0.027). Significantly, fQRS complex in the anterior/lateral leads is associated with all-cause and CV mortality stronger than fQRS in the inferior leads (P = 0.008). In a multivariate Cox regression analysis, HD patients with fQRS complex had a higher incidence of all-cause mortality (hazard ratio [HR] = 1.860; 95% confidence interval [CI]: [1.032, 3.349]; p = 0.041) and CV mortality (HR = 2.989; 95% CI [1.357, 6.584]; p = 0.007). For CAPD patients, fQRS complex was also associated with increased risk of all-cause mortality (HR = 1.593; 95% CI [1.023, 2.580]; p = 0.049) and increased risk of CV mortality (HR = 2.392; 95% CI [1.348, 4.173]; p = 0.013).

CONCLUSIONS

The presence of the fQRS complex was an independent predictor of all-cause and CV mortality in HD and CAPD patients. We suggested a potential role of the fQRS complex in CV risk strata for dialysis patients and the choice of dialysis modality.

Role of skin autofluorescence in managing renal and cardiac diseases in outpatient dermatology

INTRODUCTION

The accumulation of tissue-advanced glycation end products in skin results from complex and consecutive reactions and can be measured by skin autofluorescence (SAF) reader devices. This overview discusses studies evaluating the utilization of SAF in screening renal and cardiac disease.

MATERIALS AND METHODS

Literature search was performed using Google Scholar, PubMed, Springer, Ovid, and ScienceDirect.

RESULTS

SAF was an independent predictor of progression of chronic kidney disease (CKD) and was elevated in subjects on hemodialysis and peritoneal dialysis. Furthermore, SAF was significantly associated with cardiovascular events, cardiovascular mortality, and all-cause mortality in CKD patients. Other studies revealed a correlation between SAF and arterial stiffness, vascular damage, and subclinical atherosclerosis. A vegetarian diet was associated with lower SAF levels, whereas malnutrition was correlated with higher levels and increased mortality.

CONCLUSIONS

SAF measurement may be useful in managing renal and cardiac disease. Future studies are needed to clarify the specific role of SAF in the management of CKD and its noninvasive office utilization to identify comorbidities in inflammatory diseases, such as psoriasis.

Plasma Catestatin Levels and Advanced Glycation End Products in Patients on Hemodialysis

Catestatin (CST) is a pleiotropic peptide involved in cardiovascular protection with its antihypertensive and angiogenic effects. Considering that patients with end-stage renal disease (ESRD) who are undergoing hemodialysis (HD) are associated with higher cardiovascular risk, the aim of this study was to investigate plasma CST levels in HD patients, compare them to healthy controls and evaluate possible CST associations with advanced glycation end products (AGEs) and laboratory, anthropometric and clinical parameters. The study included 91 patients on HD and 70 healthy controls. Plasma CST levels were determined by an enzyme-linked immunosorbent assay in a commercially available diagnostic kit, while AGEs were determined using skin autofluorescence. Plasma CST levels were significantly higher in the HD group compared to the controls (32.85 ± 20.18 vs. 5.39 ± 1.24 ng/mL, p < 0.001) and there was a significant positive correlation between CST and AGEs (r = 0.492, p < 0.001). Furthermore, there was a significant positive correlation between plasma CST levels with both the Dialysis Malnutrition Score (r = 0.295, p = 0.004) and Malnutrition-Inflammation Score (r = 0.290, p = 0.005). These results suggest that CST could be playing a role in the complex pathophysiology of ESRD/HD and that it could affect the higher cardiovascular risk of patients on HD.

The AGE Reader: A non-invasive method to assess long-term tissue damage

AIMS

Advanced glycation endproducts (AGEs) are sugar-modified adducts which arise during non-enzymatic glycoxidative stress. These compounds may become systemically elevated in disease states, and accumulate in tissue, especially on long-lived proteins. AGEs have been implicated in various acute, and chronic diseases, stressing the need for reliable and comprehensive measuring techniques. Measurement of AGEs in tissue such as skin requires invasive skin biopsies. The AGE Reader has been developed to assess skin autofluorescence (SAF) non-invasively using the fluorescent properties of several AGEs.

RESULTS/CONCLUSION

Various studies have shown that SAF is a useful marker of disease processes associated with oxidative stress. It is prospectively associated with the development of cardiovascular events in patients with diabetes, renal or cardiovascular disease, and it predicts diabetes, cardiovascular disease, and mortality in the general population. However, when measuring SAF in individual subjects, several factors may limit the reliability of the measurement. These include endogenous factors present in the skin that absorb emission light such as melanin in dark-skinned subjects, but also factors that lead to temporal changes in SAF such as acute diseases and strenuous physical exercise associated with glycoxidative stress. Also, exogenous factors could potentially influence SAF levels inadvertently such as nutrition, and for example the application of skin care products. This review will address the AGE Reader functionality and the endogenous, and exogenous factors which potentially influence the SAF assessment in individual subjects.

Determinants of change in arterial stiffness over 5 years in early chronic kidney disease

BACKGROUND

Arterial stiffness (AS) is an established and potentially modifiable risk factor for cardiovascular disease associated with chronic kidney disease (CKD). There have been few studies to evaluate the progression of AS over time or factors that contribute to this, particularly in early CKD. We therefore investigated AS over 5 years in an elderly population with CKD Stage 3 cared for in primary care.

METHODS

A total of 1741 persons with an estimated glomerular filtration rate of 30-59 mL/min/1.73 m2 underwent detailed clinical and biochemical assessment at baseline and Years 1 and 5. Carotid to femoral pulse wave velocity (PWV) was measured to assess AS using a Vicorder device.

RESULTS

970 participants had PWV assessments at baseline and 5 years. PWV increased significantly by a mean of 1.1 m/s (from 9.7 ± 1.9 to 10.8 ± 2.1 m/s). Multivariable linear regression analysis identified the following independent determinants of ΔPWV at Year 5: baseline age, diabetes status, baseline systolic blood pressure (SBP) and diastolic blood pressure, baseline PWV, ΔPWV at 1 year, ΔSBP over 5 years and Δserum bicarbonate over 5 years (R2 = 0.38 for the equation).

CONCLUSIONS

We observed a clinically significant increase in PWV over 5 years in a cohort with early CKD despite reasonably well-controlled hypertension. Measures of BP were identified as the most important modifiable determinant of ΔPWV, suggesting that interventions to prevent arterial disease should focus on improved control of BP, particularly in those who evidence an early increase in PWV. These hypotheses should now be tested in prospective trials.

Higher skin autofluorescence detection using AGE-Reader™ technology as a measure of increased tissue accumulation of advanced glycation end products in dialysis patients with diabetes: a meta-analysis

This meta-analysis was conducted to compare skin autofluorescence (SAF) levels as a measure of advanced glycation end products (AGEs) accumulation between diabetic and non-diabetic dialysis patients. Relevant studies were identified primarily by searching PubMed/MEDLINE and other online databases and manual searching of cross-references. Random-effects model was used to obtain standardized mean differences (SMD) as a summary statistic. Heterogeneity was tested with meta-regression and sub-group analyses. Publication bias and robustness of this meta-analysis were tested using funnel plot and sensitivity analyses. A total of 11 reports comparing SAF between diabetic and non-diabetic dialysis patients were finally included in this meta-analysis. Dialysis patients with diabetes showed significantly higher circulatory SAF levels than their non-diabetic counterparts (SMD = 0.39; P < 0.0001). The difference was more evident in hemodialysis modality (SMD = 0.40; P < 0.0001). A one-study leave-out sensitivity analysis validated the robustness of this meta-analysis. The presence of diabetes in dialysis patients is associated with increased AGEs accumulation reflected through SAF measurements using a novel and non-invasive AGE-Reader™ technology. Our findings are in support of considering anti-AGE therapeutic strategies in addition to standard glycemic management in dialysis patients with diabetes.

Factors Associated With Change in Skin Autofluorescence, a Measure of Advanced Glycation End Products, in Persons Receiving Dialysis

Introduction

An increase over time in skin autofluorescence (SAF), a measure of accumulation of advanced glycation end products (AGE), predicts higher mortality on hemodialysis (HD). However, evidence is lacking regarding factors that contribute to changes in SAF over time in populations on dialysis. We investigated the rate of change in SAF over 1 year and the factors associated with these changes.

Methods

We enrolled 109 patients on HD and 28 on peritoneal dialysis in a prospective study. SAF was measured at baseline, 3, 6, 9, and 12 months. Rate of change in SAF was calculated using the SLOPE function in Microsoft Excel (Microsoft, Redmond, WA). Participants were then grouped into those with stable SAF or increasing SAF. Dietary AGE intake and nutritional assessments were performed at baseline, 6, and 12 months.

Results

The mean SAF trend observed was an increase of 0.30 ± 0.63 arbitrary units (AU) per year, but this varied from a decrease of 0.15 ± 0.44 to an increase of 0.76 ± 0.42 AU per year in stable and increasing SAF groups, respectively. Increasing SAF was more common in participants who developed malnutrition during the observation period, whereas those who became well-nourished were more likely to have stable SAF (8 [80%] vs. 14 [42%]; P = 0.02). Development/prevalence of malnutrition over 1 year, HD as first dialysis modality, and current smoking were independent predictors of increasing SAF.

Conclusion

SAF increases over time in most persons on dialysis. Independent determinants of increasing SAF were development/prevalence of malnutrition, HD as first dialysis modality, and current smoking. Strategies to reduce/prevent the rise in SAF, including prevention/correction of malnutrition, should be investigated in prospective studies.

The Potential Cardiovascular Benefits of Low-Glucose Degradation Product, Biocompatible Peritoneal Dialysis Fluids: A Review of the Literature

Cardiovascular mortality in the end-stage renal disease (ESRD) population remains the leading cause of death. Targeting traditional cardiovascular risk factors has proven unsuccessful in this patient population, and therefore attention has turned to risk factors related to chronic kidney disease (CKD). The toxicity of high-glucose peritoneal dialysis (PD) solutions has been well documented. The breakdown of glucose into glucose degradation products (GDP) and advanced glycation end-products (AGE) has the ability to alter cell viability and cause premature apoptosis and is strongly correlated with interstitial fibrosis and microvascular sclerosis. Biocompatible solutions have been introduced to combat the hostile milieu to which PD patients are exposed.

Given the considerable cardiovascular burden for PD patients, little is known about the cardiovascular impact the new biocompatible solutions may have. This review analyzes the existing literature regarding the mechanisms through which low-GDP solutions may modulate cardiovascular risk. Interventions using low-GDP solutions have provided encouraging changes in structural cardiovascular measures such as left ventricular mass (LVM), although metabolic changes from reduced GDP and AGE exposure yield inconclusive results on vascular remodelling. It is thought that the local effects of reduced glucose exposure may improve membrane integrity and therefore fluid status. Further research in the form of a robust randomized controlled trial should be carried out to assess the true extent of the cardiovascular benefits these biocompatible solutions may hold.

Sudden Death in End Stage Renal Disease: Comparing Hemodialysis versus Peritoneal Dialysis

BACKGROUND/AIMS

This study aimed to evaluate total and sudden death (SD) in a cohort of dialysis patients, comparing hemodialysis (HD) vs. peritoneal dialysis (PD).

METHODS

This is a multicenter retrospective cohort study.

RESULTS

Deaths were 626 out of 1,823 in HD and 62 of 249 in PD patients. HD patients had a greater number of comorbidities (p < 0.05). PD patients had a lower risk of death than HD patients (p < 0.001); however, the advantage decreased with time (p < 0.001). Mortality predictors were left ventricular ejection fraction (LVEF) ≤35%, older age, ischemic heart disease, diabetes mellitus, previous stroke, and atrial fibrillation (p < 0.03). SDs were 84:71 in HD and 13 in PD population (12.1 and 22.8% of all causes of death, respectively). A non-significant risk of SD among PD compared to HD patients was detected. SD predictors were older age, ischemic heart disease, and LVEF ≤35% (p < 0.05).

CONCLUSIONS

HD patients showed a greater presence of comorbidities and reduced survival compared to PD patients; however, the incidence of SD does not differ in the 2 populations. Video Journal Club "Cappuccino with Claudio Ronco" at http://www.karger.com/?doi=464347.

Skin advanced glycation end-products evaluation in infants according to the type of feeding and mother's smoking habits

OBJECTIVES

This study was conducted to assess whether formula-fed infants had increased skin advanced glycation end-products compared with breastfed ones. We also evaluated the effect of maternal smoke during pregnancy and lactation on infant skin advanced glycation end-products accumulation.

METHODS

Advanced glycation end-product-linked skin autofluorescence was measured in 101 infants.

RESULTS

In infants born from non-smoking mothers, advanced glycation end-products were higher in formula-fed subjects than in breastfed subjects (0.80 (0.65-0.90) vs 1.00 (0.85-1.05), p < 0.001). Advanced glycation end-products in breastfed infants from smoking mothers were higher than in those from non-smoking mothers (0.80 (0.65-0.90) vs 1.00 (0.90-1.17), p = 0.009).

CONCLUSION

Formula-fed infants had increased amounts of advanced glycation end-products compared with the breastfed ones, confirming that breast milk represents the best food for infants. Breastfed infants from mothers smoking during pregnancy and lactation had increased skin advanced glycation end-products, suggesting that smoke-related advanced glycation end-products transfer throughout breast milk. Moreover, advanced glycation end-products may already increase during gestation, possibly affecting fetal development. Thus, we reinforced that smoking must be stopped during pregnancy and lactation.

Skin Autofluorescence and Mortality in Patients on Peritoneal Dialysis

Skin autofluorescence (SAF) is a proven prognostic factor of mortality in hemodialysis patients. Traditional and nontraditional risk factors are almost equivalent in peritoneal dialysis (PD), and cardiovascular disease (CVD) is the leading cause of death. Moreover, peritoneal glucose absorption accelerates the degenerative processes of connective tissues as in diabetes. In our study, we examined the predictive value of SAF for total mortality in the PD population. Data were collected from 198 prevalently adult Caucasian PD patients. One hundred twenty-six patients (mean age 66.2 y, men [n = 73], diabetes ratio 75/126) had anamnestic CVD (coronary heart disease, cerebrovascular disease, peripheral arterial disease). Initially, we evaluated factors affecting SAF and CVD by multivariate linear regression. Survival rates were estimated by recording clinical and demographic data associated with mortality during a 36-month follow-up using the Kaplan-Meier method. Analyses were further stratified based on the presence or absence of CVD and SAF levels above or below the upper tercile 3.61 arbitrary units.Skin autofluorescence was influenced by CVD (P < 0.01, 95% confidence interval [CI] 0.1-0.5) and white blood cell counts (P < 0.001, 95% CI 0.031-0.117). According to the Spearman correlation, SAF correlated with peritoneal cumulative glucose exposure (P = 0.02) and elapsed time in PD (P = 0.008). CVD correlated with age (P < 0.001, 95% CI 1.24-1.65) and diabetes (P < 0.001, 95% CI 2.58-10.66). More deaths were observed in the high SAF group than in the low SAF group (34/68 vs 44/130; P = 0.04). Comparing the CVD(-) low SAF group survival (mean 33.9 mos, standard error [SE] 1.39) to CVD(+) low SAF (mean 30.5 mos, SE 1.37, P = 0.03) and to CVD(+) high SAF group (mean 27.1 mos, SE 1.83, P = 0.001), the difference was significant.In conclusion, among PD patients, SAF values over 3.61 arbitrary units seem to be a predictor of mortality. The relationship among peritoneal glucose exposure, CVD, and diabetes suggests its suitability to characterize systemic cumulative glucose load in this patient population.

Comparison of risk factors for cardiovascular disease in hemodialysis and peritoneal dialysis patients

OBJECTIVE

In this study, we aimed to compare the cardiovascular risk factors that might be associated with inflammation, atherosclerosis and metabolic syndrome between hemodialysis and peritoneal dialysis patients.

METHODS

Fifty hemodialysis and 50 peritoneal dialysis patients who had been receiving dialysis therapy for at least one year were included in the study. Venous blood samples were taken after 12 hours of fasting, and serum glucose, triglyceride, low-density lipoprotein (LDL)-cholesterol, high-density lipoprotein (HDL)-cholesterol, C-reactive protein, fibrinogen and homocysteine levels were measured. The presence of atherosclerotic plaques in the carotid artery was evaluated by carotid Doppler ultrasound. These data were analyzed by Student's t test, the chi-square test and the Mann-Whitney U test, as appropriate.

RESULTS

No difference was found between the hemodialysis (n=50) and peritoneal dialysis (n=50) patient groups regarding mean age, gender distribution, body mass index or dialysis duration (p=0.269, 0.683, 0.426, and 0.052, respectively). LDL-cholesterol, fibrinogen and homocysteine levels were significantly higher in peritoneal dialysis patients (p=0.006, 0.001, and 0.002, respectively). In patients with diabetes mellitus (n=17) who were undergoing renal replacement therapy, LDL-cholesterol and fibrinogen levels were significantly higher than in patients without diabetes mellitus who were undergoing renal replacement therapy (p=0.001 and 0.004, respectively).

CONCLUSION

In our study, cardiovascular risk factors (especially LDL-cholesterol) were more frequent in peritoneal dialysis patients than in hemodialysis patients.

Uremic Toxicity of Advanced Glycation End Products in CKD

Advanced glycation end products (AGEs), a heterogeneous group of compounds formed by nonenzymatic glycation reactions between reducing sugars and amino acids, lipids, or DNA, are formed not only in the presence of hyperglycemia, but also in diseases associated with high levels of oxidative stress, such as CKD. In chronic renal failure, higher circulating AGE levels result from increased formation and decreased renal clearance. Interactions between AGEs and their receptors, including advanced glycation end product-specific receptor (RAGE), trigger various intracellular events, such as oxidative stress and inflammation, leading to cardiovascular complications. Although patients with CKD have a higher burden of cardiovascular disease, the relationship between AGEs and cardiovascular disease in patients with CKD is not fully characterized. In this paper, we review the various deleterious effects of AGEs in CKD that lead to cardiovascular complications and the role of these AGEs in diabetic nephropathy. We also discuss potential pharmacologic approaches to circumvent these deleterious effects by reducing exogenous and endogenous sources of AGEs, increasing the breakdown of existing AGEs, or inhibiting AGE-induced inflammation. Finally, we speculate on preventive and therapeutic strategies that focus on the AGE-RAGE axis to prevent vascular complications in patients with CKD.

The Association between Polyclonal Combined Serum Free Light Chain Concentration and Mortality in Individuals with Early Chronic Kidney Disease

A major component of increased mortality risk in people with chronic kidney disease (CKD) is associated with non-traditional cardiovascular risk factors including markers of inflammation. We studied whether a novel marker of systemic inflammation, elevated serum combined polyclonal immunoglobulin free light chains (cFLC), was an independent risk factor for increased all-cause mortality in people with CKD stage 3. In a prospective community based cohort study, 1695 participants with stage 3 CKD and no cases of monoclonal gammopathy had cFLC concentrations measured. cFLC levels were determined using the summation of Freelite kappa and lambda assays. All other bioclinical variables were collected at the time of sample collection. Kaplan-Meier plots and Cox proportional hazards analysis was used to assess the relationship between high cFLC levels (>43.3 mg/L) and mortality. There were 167 deaths (10%) after a median of 1375 days. cFLC levels at recruitment were higher in participants who died compared with those who were alive at the end of the study; median: 46.5 mg/L (IQR: 36.1-65.4 mg/L) and 35.4 mg/L (28.1-46.6 mg/L) respectively, P <0.001. Kaplan-Meier survival analysis demonstrated participants with cFLC >43.3 mg/L levels had an increased risk of mortality compared to people with normal cFLC levels (P <0.001). Elevated cFLC levels were independently associated with worse survival (Hazard ratio: 1.50; 95% confidence interval: 1.04-2.16; P=0.03). Other independent risk factors for worse survival were: older age, male gender, previous cardiovascular event, lower eGFR and higher high sensitivity C-reactive protein (hsCRP). To conclude, high cFLC levels predict increased mortality in people with stage 3 CKD, independent of established risk factors and other markers of inflammation.

Skin autofluorescence as a novel marker of vascular damage in children and adolescents with chronic kidney disease

BACKGROUND

Skin autofluorescence (sAF) was examined as a marker of the accumulation of advanced glycation end products (AGEs) in tissues of children with chronic kidney disease (CKD) in relation to renal function, dialysis modality and markers of endothelial inflammation and dysfunction.

METHODS

A total of 76 children with CKD were enrolled in the study, of whom 20 children were on hemodialysis (HD), 20 were on peritoneal dialysis (PD) and 36 were treated conservatively. A control group of 26 healthy subjects was also included in the study. In all children, sAF intensity, carotid intima-media (cIMT) thickness and plasma concentrations of sE-selectin, matrix metalloproteinase 9 (MMP-9), tissue inhibitor of metalloproteinase 1 (TIMP-1), asymmetric dimethylarginine (ADMA), symmetric dimethylarginine (SDMA) and plasminogen activator inhibitor type 1 (PAI-1) were measured.

RESULTS

Compared to the controls, children with CKD had significantly elevated sAF levels. sAF in the children with CKD was positively correlated with sE-selectin, MMP-9, TIMP-1, ADMA, SDMA and PAI-1 levels. In the predialysis group (conservative treatment) sAF levels were positively correlated with sE-selectin and ADMA levels and negatively correlated with glomerular filtration rate. Multiple regression analysis showed a significant association of sAF with sE-selectin and MMP-9 in CKD children.

CONCLUSIONS

The results reveal that AGEs were accumulated in the children with CKD. This accumulation was related to early vascular changes and a number of biochemical vascular risk markers. sAF measurement, as a noninvasive method, may be useful for identification of clinical risk factors of vascular disease in CKD children.

Hemodialysis-associated cardiomyopathy: a newly defined disease entity

Cardiovascular disease is the most common cause of the greatly elevated rates of mortality characteristic of patients undergoing maintenance hemodialysis. This article is an attempt to describe the complex and evolving features of cardiac disease routinely encountered in HD patients. Furthermore, by trying to appreciate the pathophysiological drivers, and the crucial interaction with the HD treatment itself, this article seeks to define cardiac disease in this setting (HD-associated cardiomyopathy) as a unique and complex entity. By understanding the phenotype and basis of HD-associated cardiomyopathy, we can develop an evolved understanding of the dominant processes involved in its development and offer up dialysis-based interventions specifically designed to mitigate the cumulative ischemic insults consequent to conventional HD treatment. This article explores the justification of this approach and recent evidence of its efficacy.

Skin Autofluorescence - A Non-invasive Measurement for Assessing Cardiovascular Risk and Risk of Diabetes

The results of the Diabetes Control and Complications Trial-Epidemiology of Diabetes Interventions and Complications (DCCT-EDIC) study have strengthened the 'glycaemic memory' concept, postulating that the quality of metabolic control over several years predicts the development of diabetic complications. To mirror long-term metabolic control, the degree of glycated haemoglobin (HbA_1c) might not represent the optimal biomarker. Other substances with a longer persistence, like the so-called advanced glycation end-products (AGEs), which probably form the substrate of the glycaemic memory, might perform better. Newly developed methods such as the assessment of skin autofluorescence (SAF), enable fast, uncomplicated and non-invasive AGEs assessment. SAF was validated for diabetes screening and shows a good predictive value for the development of diabetic and cardiovascular complications. This article deals with the theoretical background and with available clinical data on this new variable.

Vascular effects of advanced glycation endproducts: Clinical effects and molecular mechanisms

The enhanced generation and accumulation of advanced glycation endproducts (AGEs) have been linked to increased risk for macrovascular and microvascular complications associated with diabetes mellitus. AGEs result from the nonenzymatic reaction of reducing sugars with proteins, lipids, and nucleic acids, potentially altering their function by disrupting molecular conformation, promoting cross-linking, altering enzyme activity, reducing their clearance, and impairing receptor recognition. AGEs may also activate specific receptors, like the receptor for AGEs (RAGE), which is present on the surface of all cells relevant to atherosclerotic processes, triggering oxidative stress, inflammation and apoptosis. Understanding the pathogenic mechanisms of AGEs is paramount to develop strategies against diabetic and cardiovascular complications.

Tissue advanced glycation end product deposition after kidney transplantation

BACKGROUND

Tissue advanced glycation end products (AGEs) accumulate in chronic kidney disease (CKD) and are a measure of cumulative metabolic stress. Measurement of tissue AGEs by skin autofluorescence (SAF) correlates well with cardiovascular outcomes in dialysis patients. SAF levels in transplant recipients relative to CKD and dialysis patients have not been previously studied, and the impact of transplantation on SAF levels in dialysis patients is unknown.

METHODS

SAF was measured using an AGE reader in 66 patients who had received a kidney transplant. Values were compared to those obtained in 1,707 patients with CKD stage 3 and in 115 patients on dialysis.

RESULTS

Mean SAF in transplant recipients [2.81 ± 0.64 arbitrary units (AU)] was significantly lower than in patients on haemodialysis (3.73 ± 0.88 AU) and peritoneal dialysis (3.57 ± 0.75 AU; p < 0.001), but was no different from CKD stage 3 (2.79 ± 0.66 AU; p = 0.42). In the transplant group, SAF correlated most strongly with age (r = 0.316). There was no correlation between SAF and estimated glomerular filtration rate or renal replacement therapy vintage. A small cohort of patients with SAF recorded on dialysis and following transplantation showed a drop in SAF over a mean time of 16 months after transplantation.

DISCUSSION

Tissue AGE values in kidney transplant recipients are significantly lower than in patients receiving dialysis and similar to those in patients with CKD stage 3. Our data suggest that transplantation may be associated with a reduction in tissue AGEs, and this might be an important component of the observed reduction in cardiovascular risk in transplant recipients compared to patients on dialysis.

Variability of skin autofluorescence measurement over 6 and 12 weeks and the influence of benfotiamine treatment

BACKGROUND

Measurements of skin autofluorescence (SAF) allow for a simple and noninvasive quantification of tissue advanced glycation end-products (AGEs), a marker linked to the risk of diabetes complications. The aim of this study was to test the repeatability of SAF over 6 and 12 weeks and to test whether benfotiamine, a thiamine prodrug suggested to reduce AGEs formation under hyperglycemic conditions, is able to attenuate SAF when administered over 6 weeks.

PATIENTS AND METHODS

In a double-blind, placebo-controlled, randomized, crossover study, 22 patients with type 2 diabetes mellitus (T2DM) received 900 mg/day benfotiamine or placebo for 6 weeks (washout period of 6 weeks between). At the beginning and at the end of each treatment period, SAF was assessed in the fasting state, as well as 2, 4, and 6 h following a mixed test meal.

RESULTS

The respective intra-individual and inter-individual variability of fasting SAF was 6.9% and 24.5% within 6 weeks and 10.9% and 23.1% within 12 weeks. The respective variability calculated for triplicate comparisons was 9.9% and 27.7%. A short-term therapy with benfotiamine did not influence SAF significantly, nor did we find a significant postprandial SAF increase.

CONCLUSIONS

In patients with T2DM, repeated, timely spaced SAF measurements have an intra-subject variability of below 11%. Using these data, sample sizes were calculated for interventional studies aiming at reducing SAF. Benfotiamine treatment for 6 weeks did not significantly influence SAF; for this, a longer-term therapy is probably needed.

Elevated levels of procoagulant plasma microvesicles in dialysis patients

Cardiovascular (CV) death remains the largest cause of mortality in dialysis patients, unexplained by traditional risk factors. Endothelial microvesicles (EMVs) are elevated in patients with traditional CV risk factors and acute coronary syndromes while platelet MVs (PMVs) are associated with atherosclerotic disease states. This study compared relative concentrations of circulating MVs from endothelial cells and platelets in two groups of dialysis patients and matched controls and investigated their relative thromboembolic risk. MVs were isolated from the blood of 20 haemodialysis (HD), 17 peritoneal dialysis (PD) patients and 20 matched controls. Relative concentrations of EMVs (CD144(+ ve)) and PMVs (CD42b(+ ve)) were measured by Western blotting and total MV concentrations were measured using nanoparticle-tracking analysis. The ability to support thrombin generation was measured by reconstituting the MVs in normal plasma, using the Continuous Automated Thrombogram assay triggered with 1µM tissue factor. The total concentration of MVs as well as the measured sub-types was higher in both patient groups compared to controls (p<0.05). MVs from HD and PD patients were able to generate more thrombin than the controls, with higher peak thrombin, and endogenous thrombin potential levels (p<0.02). However there were no differences in either the relative quantity or activity of MVs between the two patient groups (p>0.3). Dialysis patients have higher levels of circulating procoagulant MVs than healthy controls. This may represent a novel and potentially modifiable mediator or predictor of occlusive cardiovascular events in these patients.

Peritoneal changes in patients on long-term peritoneal dialysis

Long-term peritoneal dialysis can lead to morphological and functional changes in the peritoneum. Although the range of morphological alterations is known for the peritoneal dialysis population as a whole, these changes will not occur in every patient in the same sequence and to the same extent. Longitudinal studies are therefore required to help identify which patients might develop the changes. Although longitudinal studies using peritoneal biopsies are not possible, analyses of peritoneal effluent biomarkers that represent morphological alterations could provide insight. Longitudinal studies on peritoneal transport have been performed, but follow-up has often been too short and an insufficient number of parameters have been investigated. This Review will firstly describe peritoneal morphology and structure and will then focus on peritoneal effluent biomarkers and their changes over time. Net ultrafiltration will also be discussed together with the transport of small solutes. Data on the peritoneal transport of serum proteins show that serum protein levels do not increase to the same extent as levels of small solutes with long-term peritoneal dialysis. Early alterations in peritoneal transport must be distinguished from alterations that only develop with long-term peritoneal dialysis. Early alterations are related to vasoactive mediators, whereas later alterations are related to neoangiogenesis and fibrosis. Modern peritoneal dialysis should focus on the early detection of long-term membrane alterations by biomarkers--such as cancer antigen 125, interleukin-6 and plasminogen activator inhibitor 1--and the improved assessment of peritoneal transport.

Diabetic muscle infarction: a rare cause of acute limb pain in dialysis patients

Diabetic muscle infarction is a rare microangiopathic complication occurring in patients with advanced diabetes mellitus. Diabetic patients with chronic kidney disease stage Vd are prone to develop this complication. The presenting symptom is a localized painful swelling of the affected limb. Symptoms usually resolve spontaneously during the following weeks, but frequent relapse can occur and in some cases swelling may lead to compartment syndrome. Biochemical blood analyses show an elevated C-reactive protein, but creatine kinase is often normal. Diagnosis can be made on clinical presentation and imaging, with magnetic resonance imaging as the gold standard. Histology is often not contributive. Treatment consists of rest, analgesics, rigorous glycemic control and low-dose aspirin. Severe cases of compartment syndrome require fasciotomy. In the current paper, we present two diabetic patients with cystic fibrosis, who are treated with automated peritoneal dialysis and suffered from episodic lower limb infarction. We subsequently review 48 episodes of diabetic muscle infarction previously reported in the literature in patients with end-stage renal disease.

Skin autofluorescence as a marker of cardiovascular risk in children with chronic kidney disease

BACKGROUND

We examined skin autofluorescence (sAF) in chronic kidney disease children (CKD) in relation to renal function and dialysis modality.

METHODS

Twenty children on hemodialysis (HD), 20 on peritoneal dialysis (PD), 36 treated conservatively, and 26 healthy subjects were enrolled into the study. In all children sAF, pulse-wave velocity indexed to height (PWV/ht), left ventricular mass index (LVMI), blood pressure (BP), serum lipid profile, phosphate (P), calcium (Ca), and homocysteine were measured.

RESULTS

sAF was significantly elevated in CKD groups vs. controls and was significantly associated with PWV/ht, LVMI, BP, P, Ca × P product and homocysteine. sAF in HD and PD groups was positively correlated with dialysis vintage, and in the predialysis group negatively correlated with glomerular filtration rate (eGFR). Multiple regression analysis showed significant association of sAF with LVMI and P in the CKD patient group, and with dialysis treatment duration and BP in dialyzed children.

CONCLUSIONS

In CKD children, tissue accumulation of advanced glycation end-products (AGEs) was observed. This was aggravated as eGFR declined and was related to early cardiovascular changes and some biochemical cardiovascular disease (CVD) risk markers. sAF as a non-invasive method may be a useful tool for identification of a clinical risk factors of cardiovascular disease in CKD children.

Skin autofluorescence measurement in diabetological and nephrological clinical practice

Formation of advanced glycation end-products plays role in the pathogenesis of diabetic complications and related ongoing connective tissue degeneration as part of atherosclerosis and chronic kidney disease. The cumulative metabolic burden of patients can be measured in few minutes using a recently developed non-invasive mobile device, which has been developed for the evaluation of fluorescent advanced glycation end-product molecules in skin. The variation of skin autofluorescence measurement is about 10%, and its predictive value in cardiovascular events overcomes conventional glycemic markers even in chronic kidney disease population. In the early stages of diabetes it seems to be an effective screening tool, and in overt diabetes signifies micro- and macrovascular complications. This method is unadaptable in systemic autoimmune diseases, generalised dermatological illnesses and hepatobiliary pathological conditions leading to icterus. Significant correlation has been found between skin autofluorescence and pulse wave velocity due to glycation of vascular wall structure proteins and consequent arterial matrix rigidity. Orv. Hetil., 2012, 153, 1651–1657.

Accumulation of tissue advanced glycation end products correlated with glucose exposure dose and associated with cardiovascular morbidity in patients on peritoneal dialysis

OBJECTIVES

Accumulation of tissue advanced glycation end products (AGEs) is a marker of cumulative glycemic and/or oxidative stress. Cutaneous AGEs levels measured by skin autofluorescence correlate well with cardiovascular outcomes in diabetes and hemodialysis (HD) patients. The present study aimed to compare tissue AGEs levels with peritoneal dialysis (PD) and HD patients and to evaluate the relationship between skin autofluorescence and cardiovascular morbidity in patients on PD.

METHODS

A total of 2388 maintenance dialysis patients (613 PD and 1775 HD) were enrolled in this cross-sectional study. Skin autofluorescence was measured non-invasively with an autofluorescence reader. Cardiovascular morbidity was defined as clinically diagnosed ischemic heart disease, heart failure, stroke or peripheral vascular disease from initiation of dialysis.

RESULTS

More than 90% of patients on both PD and HD had met current dialysis adequacy targets. Compared to HD group, PD patients receiving conventional glucose-containing dialyzate had significantly higher skin autofluorescence values in each category of age and dialysis duration, irrespective of the presence or absence of diabetes. In PD patients, skin autofluorescence values were strongly correlated with the duration of PD and glucose exposure dose and independently associated with cardiovascular morbidity. Multivariate analysis revealed that glucose exposure dose and skin autofluorescence were the strongest risk factors for cardiovascular morbidity in PD patients after adjustment by age, gender, and other classic- or uremic-related risk factors.

CONCLUSIONS

Accumulation of tissue AGEs provides a potential link between PD exposure of metabolic stress and progression of cardiovascular disease in patients on PD.

Skin autofluorescence and the association with renal and cardiovascular risk factors in chronic kidney disease stage 3

BACKGROUND AND OBJECTIVES

Tissue advanced glycation end products (AGE) accumulation is a measure of cumulative metabolic stress. Assessment of tissue AGE by skin autofluorescence (SAF) correlates well with cardiovascular (CV) outcomes in diabetic, transplant, and dialysis patients, and may be a useful marker of CV risk in earlier stages of chronic kidney disease (CKD).

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

1707 patients with estimated GFR 59 to 30 ml/min per 1.73 m(2) were recruited from primary care practices for the Renal Risk In Derby (RRID) study. Detailed medical history was obtained, and each participant underwent clinical assessment as well as urine and serum biochemistry tests. SAF was assessed (mean of three readings) as a measure of skin AGE deposition using a cutaneous AF device (AGE Reader™, DiagnOptics, Groningen, The Netherlands).

RESULTS

Univariate analysis revealed significant correlations between AF readings and several potential risk factors for cardiovascular disease (CVD) and progression of CKD. SAF readings (arbitrary units) were also significantly higher among males (2.8 ± 0.7 versus 2.7 ± 0.6), diabetics (3.0 ± 0.7 versus 2.7 ± 0.6), patients with evidence of self-reported CVD (2.9 ± 0.7 versus 2.7 ± 0.6), and those with no formal educational qualifications (2.8 ± 0.6 versus 2.6 ± 0.6; P < 0.01 for all). Multivariable linear regression analysis identified hemoglobin, diabetes, age, and eGFR as the most significant independent determinants of higher SAF (standardized coefficients -0.16, 0.13, 0.12, and -0.10, respectively; R(2) = 0.17 for equation).

CONCLUSION

Increased SAF is independently associated with multiple CV and renal risk factors in CKD 3. Long-term follow-up will assess the value of SAF as a predictor of CV and renal risk in this population.

"NEPP" peritoneal dialysis regimen has beneficial effects on plasma CEL and 3-DG, but not pentosidine, CML, and MGO

BACKGROUND

Standard peritoneal dialysis (PD) solutions contain high levels of glucose and glucose degradation products (GDPs), both contributing to the formation of advanced glycation end products (AGEs). We studied the contribution to plasma GDP and AGE levels of 2 PD regimens that differ in glucose and GDP loads: high load [standard PD (sPD) using 4 glucose-lactate exchanges] and low load [1 amino acid exchange, 1 icodextrin exchange, and 2 glucose-bicarbonate/lactate exchanges ("NEPP")].

METHODS

In a prospective crossover study (2 periods of 24 weeks), new continuous ambulatory PD patients were randomized to NEPP-sPD (n = 23) or to sPD-NEPP (n = 27).

RESULTS

After the start of PD, absolute increases were observed in plasma levels of 3-deoxyglucosone (3-DG, 220.4 nmol/L, p < 0.0001) and in N(ε)-(carboxymethyl) lysine (CML) in plasma proteins (0.02 μmol/L CML per 1 mol/L lysine, p < 0.0001). During the first 6 weeks, 3-DG tended to increase more with sPD treatment (p = 0.08), and CML, with NEPP treatment (p = 0.002). In both groups, N(ε)-(carboxyethyl)lysine (CEL) in plasma proteins declined significantly with the start of PD. Treatment with NEPP resulted in higher levels of methylglyoxal (MGO) and lower levels of 3-DG and CEL. Pentosidine in the albumin fraction tended to increase less during NEPP treatment.

CONCLUSIONS

A low glucose and GDP PD regimen (NEPP) resulted in plasma levels of 3-DG and CEL that were lower than those with a glucose-based sPD regimen. Starting PD with NEPP was associated with a steeper increase in CML, and continuing treatment with NEPP resulted in higher MGO levels.

Skin autofluorescence as a measure of advanced glycation endproduct deposition: a novel risk marker in chronic kidney disease

PURPOSE OF REVIEW

Skin autofluorescence (SAF) is a new method to noninvasively assess accumulation of advanced glycation endproducts (AGEs) in a tissue with low turnover. Recent progress in the clinical application of SAF as a risk marker for diabetic nephropathy as well as cardiovascular disease in nondiabetic end-stage kidney disease, less advanced chronic kidney disease, and renal transplant recipients is reviewed.

RECENT FINDINGS

Experimental studies highlight the fundamental role of the interaction of AGEs with the receptor for AGEs (RAGEs), also called the AGE-RAGE axis, in the pathogenesis of vascular and chronic kidney disease. SAF predicts (cardiovascular) mortality in renal failure and also chronic renal transplant dysfunction. Long-term follow-up results from the Diabetes Control and Complications Trial and UK Prospective Diabetes Study suggest that AGE accumulation is a key carrier of metabolic memory and oxidative stress. Short-term intervention studies in diabetic nephropathy with thiamine, benfotiamine and angiotensin-receptor blockers aimed at reducing AGE formation have reported mixed results.

SUMMARY

SAF is a noninvasive marker of AGE accumulation in a tissue with low turnover, and thereby of metabolic memory and oxidative stress. SAF independently predicts cardiovascular and renal risk in diabetes, as well as in chronic kidney disease. Further long-term studies are required to assess the potential benefits of interventions to reduce AGE accumulation.

Peritoneal dialysis is not associated with myocardial stunning

BACKGROUND

Hemodynamic changes during hemodialysis can precipitate subclinical myocardial ischemia, which over time contributes to the development of cardiac failure and is associated with a poor prognosis. Peritoneal dialysis (PD) is also associated with acute changes in systemic hemodynamics and a similarly high incidence of cardiovascular disease; we therefore sought to examine whether the hemodynamic effects of a PD exchange would be sufficient to induce subclinical myocardial ischemia.

METHODS

10 patients on PD entered a prospective observational study to determine whether left ventricular (LV) regional wall motion abnormalities (RWMAs) developed following a dialysate exchange. Serial echocardiography with quantitative analysis was used to assess ejection fraction and regional systolic LV function (shortening fraction). Blood pressure (BP) and hemodynamic variables were measured using continuous pulse wave analysis.

RESULTS

We observed a very low frequency of RWMA development (5/100 regions). Only 1 patient had more than 1 RWMA and 6 patients were entirely unaffected. Overall mean shortening fraction increased when comparing pre and post values for both 2-chamber (from 3.06% ± 1.5% to 4.26% ± 1.3%, p = 0.001) and 4-chamber (from 3.00% ± 0.7% to 3.67% ± 0.9%, p = 0.021) analyses. Mean arterial pressure fell by a small degree during drainage of dialysate, with a larger rise in BP observed during instillation. These changes were driven by changes in peripheral resistance that fell during drainage and rose during instillation.

CONCLUSIONS

In contrast to hemodialysis, the acute effects of PD do not result in subclinical myocardial ischemia.

Reducing cardiometabolic risk in peritoneal dialysis patients: role of the dialysis solution

Peritoneal dialysis (PD) is a well-established form of therapy for stage 5 chronic kidney disease requiring renal replacement therapy. D-Glucose has been used successfully for several decades as the osmotic agent employed in dialysis solutions to achieve adequate fluid removal. The absorption of 100-200 grams of glucose per day has been suggested as potentially increasing cardiometabolic risk, particularly in patients with diabetes. Supporting and undermining evidence for this hypothesis is reviewed, with a focus on the role of glucose absorption in changes in body composition, dyslipidemia, and glycemic control in diabetic PD patients. Clinical strategies to optimize fluid removal while minimizing the metabolic impact of glucose absorption are also discussed.