The emerging pleiotrophic role of adipokines in the uremic phenotype:

Serum vaspin levels and carotid intima-media thickness in predialysis patients

BACKGROUND AND OBJECTIVE

Visceral adipose tissue-derived serine proteinase inhibitor (vaspin) is an adipokine that correlates with insulin resistance and obesity in human beings. Previous studies have evaluated the serum vaspin levels in several diseases such as chronic haemodialysis patients and coronary artery disease. To our knowledge, serum vaspin levels have not yet been reported in predialysis patients. Carotid intima-media thickness (CIMT) is a noninvasive procedure to detect early atherosclerotic changes. The aim of this study was to evaluate serum vaspin levels in predialysis patients and their relationships with glomerular filtration rate and CIMT levels.

METHODS

A total of twenty-five predialysis patients (14 females and 11 males) and 22 healthy subjects (8 females and 14 males) were enrolled in the study. Serum samples were subjected to the human vaspin RIA system. CIMT was measured by B-mode ultrasonography.

RESULTS

Serum vaspin levels were significantly lower in predialysis patients than control subjects (P < .05), while CIMT levels were significantly higher (P < .001). Serum vaspin levels were found to be significantly correlated with glomerular filtration rate (r = 0.42, P < .001) and CIMT (r = -0.47, P < .05) in predialysis patients.

CONCLUSIONS

This is the first report to describe the association between serum vaspin levels and CIMT in predialysis patients. We concluded that serum vaspin levels were decreased in predialysis patients than control subjects. In addition, serum vaspin levels were found to be significantly correlated with glomerular filtration rate and CIMT.

Sex and gender differences in chronic kidney disease: progression to end-stage renal disease and haemodialysis

Sex and gender differences are of fundamental importance in most diseases, including chronic kidney disease (CKD). Men and women with CKD differ with regard to the underlying pathophysiology of the disease and its complications, present different symptoms and signs, respond differently to therapy and tolerate/cope with the disease differently. Yet an approach using gender in the prevention and treatment of CKD, implementation of clinical practice guidelines and in research has been largely neglected. The present review highlights some sex- and gender-specific evidence in the field of CKD, starting with a critical appraisal of the lack of inclusion of women in randomized clinical trials in nephrology, and thereafter revisits sex/gender differences in kidney pathophysiology, kidney disease progression, outcomes and management of haemodialysis care. In each case we critically consider whether apparent discrepancies are likely to be explained by biological or psycho-socioeconomic factors. In some cases (a few), these findings have resulted in the discovery of disease pathways and/or therapeutic opportunities for improvement. In most cases, they have been reported as merely anecdotal findings. The aim of the present review is to expose some of the stimulating hypotheses arising from these observations as a preamble for stricter approaches using gender for the prevention and treatment of CKD and its complications.

Visceral Adipose Tissue and Leptin Hyperproduction Are Associated With Hypogonadism in Men With Chronic Kidney Disease

OBJECTIVE

Hypogonadism is a common endocrine disorder in men with chronic kidney disease (CKD), but its pathophysiology is poorly understood. We here explore the plausible contribution of abdominal adiposity and leptin hyperproduction to testosterone deficiency in this patient population.

DESIGN

Cross-sectional analysis with all men included the Malnutrition, Inflammation and Vascular Calcification cohort, which enrolled consecutive nondialyzed patients with CKD stages 3-5.

SUBJECTS

A total of 172 men with CKD stages 3-5 nondialysis (median age 61 [45-75] years, median glomerular filtration rate 24 [9-45] mL/min/1.73 m²). In them, serum levels of total testosterone, estrogen, sex hormone binding globulin, and leptin were quantified, together with visceral adipose tissue (VAT) by thoracic and abdominal CT scan.

INTERVENTION

None, observational study.

MAIN OUTCOME MEASURE

Total testosterone, hypogonadism.

RESULTS

The median level of total testosterone was 11.7 (7.3-18.4) nmol/L, with hypogonadism (<10 nmol/L) present in 52 (30%) patients. Testosterone-deficient patients presented with significantly higher body mass index, waist circumference, and VAT. An inverse correlation between testosterone and VAT (rho = -0.25, P = .001) or waist circumference (rho = -0.20, P = .008) was found, also after multivariate adjustment including sex hormone binding globulin and estrogen. Total testosterone was inversely correlated with serum leptin (rho = -0.22, P = .003), and the ratio of leptin/VAT, an index of leptin hyperproduction, was strongly and independently associated with the prevalence of hypogonadism in multivariable regression analyses.

CONCLUSION

Visceral adiposity independently associated with lower testosterone levels among men with CKD stage 3-5 nondialysis. The observed link between hyperleptinemia and hypogonadism is in line with previous evidence on direct effects of leptin on testosterone production.

The correlation of inflammatory markers and plasma vaspin levels in patients with diabetic nephropathy

Vaspin, a recently identified adipokine, is a visceral adipose tissue-derived serine protease inhibitor that may have insulin sensitizing effect on adipose tissue. Herein, we measured vaspin level in patients with different stages of diabetic nephropathy (DNP), and investigated the correlation of the vaspin level with other inflammatory parameters. 106 adult type 2 diabetic patients with no known chronic inflammatory disease were included and grouped according to the stage of DNP: Albuminuria <30 mg/day and estimated glomerular filtration rate (eGFR) > 60 mL/min/1.73m(2) (Group-1); albuminuria 30-300 mg/day and eGFR >60 mL/min/1.73m(2) (Group-2); albuminuria >300 mL/min and eGFR <60 mL/min/1.73m(2) (Group-3). Demographic, clinical and laboratory data were recorded as well as vaspin, high sensitivity C-reactive protein (hsCRP), interleukin (IL)-1 and tumor necrosis factor (TNF)-α levels. There were 38, 35 and 33 patients in Group 1, 2 and 3, respectively. Groups were similar regarding age and gender. Vaspin level did not differ between groups. When all the groups were considered, vaspin was positively correlated with IL-6 level (r = 0.215, p = 0.041). No correlation of vaspin was found with IL-1, TNF-α and hsCRP levels (p = 0.580, r = 0.054; p = 0.463, r = 0.072; p = 0.812, r = 0.025, respectively). Vaspin levels of the patients with GFR ≥60 mL/min/1.73m(2) was less than that of patients with GFR <60 mL/min/1.73m(2) (p = 0.03). Age and IL-6 were found to be the major determinants of vaspin level with linear regression analysis. In patients with DNP, vaspin level does not change within the early stages of DNP; while it is higher in patients with decreased GFR, which may be related with increasing inflammation regardless of the stage of the kidney disease.

Validating Appetite Assessment Tools Among Patients Receiving Hemodialysis

OBJECTIVE

To test the performance of appetite assessment tools among patients receiving hemodialysis (HD).

DESIGN

Cross-sectional.

SUBJECTS

Two hundred twenty-one patients receiving HD enrolled in seven dialysis facilities in Northern California.

INTERVENTION

We assessed 5 appetite assessment tools (self-assessment of appetite, subjective assessment of appetite, visual analog scale [VAS], Functional Assessment of Anorexia/Cachexia Therapy [FAACT] score, and the Anorexia Questionnaire [AQ]).

MAIN OUTCOME MEASURES

Reported food intake, normalized protein catabolic rate, and change in body weight were used as criterion measures, and we assessed associations among the appetite tools and biomarkers associated with nutrition and inflammation. Patients were asked to report their appetite and the percentage of food eaten (from 0% to 100%) during the last meal compared to usual intake.

RESULTS

Fifty-eight (26%) patients reported food intake ≤ 50% (defined as poor appetite). The prevalence of anorexia was 12% by self-assessment of appetite, 6% by subjective assessment of appetite, 24% by VAS, 17% by FAACT score, and 12% by AQ. All the tools were significantly associated with food intake ≤ 50% (P < .001), except self-assessment of appetite. The FAACT score and the VAS had the strongest association with food intake ≤ 50% (C-statistic 0.80 and 0.76). Patients with food intake ≤ 50% reported weight loss more frequently than patients without low intake (36% vs 22%) and weight gain less frequently (19% vs 35%; P = .03). Normalized protein catabolic rate was lower among anorexic patients based on the VAS (1.1 ± 0.3 vs 1.2 ± 0.3, P = .03). Ln interleukin-6 correlated inversely with food intake (P = .03), but neither interleukin-6 nor C-reactive protein correlated with any of the appetite tools. Furthermore, only the self-assessment of appetite was significantly associated with serum albumin (P = .02), prealbumin (P = .02) and adiponectin concentrations (P = .03).

CONCLUSIONS

Alternative appetite assessment tools yielded widely different estimates of the prevalence of anorexia in HD. When considering self-reported food intake as the criterion standard for anorexia, the FAACT score and VAS discriminated patients reasonably well.

Epicardial fat accumulation, cardiometabolic profile and cardiovascular events in patients with stages 3-5 chronic kidney disease

BACKGROUND

It has been hypothesized that epicardial adipose tissue (EAT) exerts pathogenic effects on cardiac structures. We analysed the associations between EAT and both cardiovascular (CV) disease risk factors and CV events in patients with chronic kidney disease (CKD).

PATIENTS AND METHODS

We included 277 nondialysed patients [median age 61, interquartile range (IQR) 53-68 years; 63% men] with stages 3-5 CKD in this cross-sectional evaluation. EAT and abdominal visceral adipose tissue (VAT) were assessed by computed tomography. Patients were followed for median 32 (IQR 20-39) months, and the composite of fatal and nonfatal CV events was recorded.

RESULTS

With increasing EAT quartiles, patients were older, had higher glomerular filtration rate, body mass index, waist, VAT and coronary calcification, higher levels of haemoglobin, triglycerides, albumin, C-reactive protein and leptin and higher prevalence of left ventricular hypertrophy and myocardial ischaemia; total and high-density lipoprotein cholesterol, 25-hydroxy-vitamin D and 1, 25-dihydroxy-vitamin D progressively decreased. Associations between EAT and cardiac alterations were not independent of VAT. During follow-up, 58 CV events occurred. A 1-SD higher EAT volume was associated with an increased risk of CV events in crude [hazard ratio (HR) 1.41, 95% confidence interval (CI) (1.12-1.78) and adjusted (HR 1.55, 95% CI 1.21-1.99) Cox models. However, adding EAT to a standard CV disease risk prediction model did not result in a clinically relevant improvement in prediction.

CONCLUSION

Epicardial adipose tissue accumulation in patients with CKD increases the risk of CV events independent of general adiposity. This is consistent with the notion of a local pathogenic effect of EAT on the heart or heart vessels, or both. However, EAT adds negligible explanatory power to standard CV disease risk factors.

Visceral adipose tissue is associated with insulin resistance in hemodialyzed patients

BACKGROUND

It has not been definitively established which factors affect insulin resistance (IR) and whether dialysis decreases IR. The aim of this study was to investigate factors that may have an influence on homeostasis model assessment (HOMA-IR) in hemodialyzed patients (HDpts) and to compare IR between HDpts and healthy subjects.

MATERIAL AND METHODS

We examined 33 HDpts and paired 33 subjects of the control group, matched for sex, age, and BMI. We analyzed concentrations of insulin, glucose, leptin, resistin, and total and high-molecular-weight adiponectin (HMWad) in serum. Using computed tomography in HDpts, we evaluated visceral adipose tissue (VAT), concentrations of visfatin, CRP, and IL-6.

RESULTS

HOMA-IR (median, 1.3 vs. 1.4, P=0.19), insulin (median 6.8 vs. 6.0 µIU/mL, P=0.7), glucose (79 mg/dL vs. 93 mg/dL, P=0.001). IR in HDpts is dependent on VAT (r=0.36, P=0.04) and this relationship is stronger than the relationship of BMI and IR (r=0.3, P=0.1). In HDpts we found higher concentrations of leptin (P=0.001) and resistin (P<0.001), with no relation to IR. HMWad and its percentage in relation to total adiponectin are higher in HDpts (P=0.03 and P<0.001, respectively).

CONCLUSIONS

HOMA-IR in HDpts does not differ from the control group. In HDpts it depends on the quantity of VAT and this relationship is stronger than with BMI. In HDpts leptin and resistin do not influence IR. HMWad and its percentage in total adiponectin are significantly higher in HDpts.

Leptin as an uremic toxin: Deleterious role of leptin in chronic kidney disease

White adipose tissue secretes a large variety of compounds named adipokines amongst which, leptin exhibits pleiotropic metabolic actions. Leptin is an anorexigenic hormone, secreted in proportion of fat mass, with additional effects on the regulation of inflammation, cardiovascular system, immunity, hematopoiesis and bone metabolism. Chronic kidney disease (CKD) is characterized by an increase of plasma leptin concentration that may be explained by a lack of renal clearance. Hyperleptinemia plays a key role in the pathogenesis of complications associated with CKD such as cachexia, protein energy wasting, chronic inflammation, insulin resistance, cardiovascular damages and bone complications. Leptin is also involved in the progression of renal disease through its pro-fibrotic and pro-hypertensive actions. Most of the adverse effects of leptin have been documented both experimentally and clinically. Leptin may therefore be considered as an uremic toxin in CKD. The aim of this review is to summarize the pathophysiological and clinical role of leptin in in vitro studies, experimental models, as well as in patients suffering from CKD.

The peptidic middle molecules: is molecular weight doing the trick?

Chronic kidney disease (CKD) is characterized by a gradual endogenous intoxication caused by the progressive accumulation of bioactive compounds that in normal conditions would be excreted and/or metabolized by the kidney. Uremic toxicity now is understood as one of the potential causes for the excess of cardiovascular disease and mortality observed in CKD. An important family of uremic toxins is that of the peptidic middle molecules, with a molecular weight ranging between 500 and 60,000 Da, which makes them, as a consequence, difficult to remove in the process of dialysis unless the dialyzer pore size is large enough. This review provides an overview of the main and best-characterized peptidic middle molecules and their role as potential culprits of the cardiometabolic complications inherent to CKD patients.

Association of serum vaspin and adiponectin levels with renal function in patients with or without type 2 diabetes mellitus

Vaspin and adiponectin are two adipocytokines with antidiabetic effects. Some studies reported that levels of adiponectin and vaspin were correlated with decreased glomerular filtration rate (FGR) and increased albuminuria. We therefore evaluated the vaspin and adiponectin levels in renal insufficiency (RI) patients with or without T2DM. Serum vaspin, adiponectin levels were measured in 416 subjects with or without T2DM. Analysis was made between groups divided by these subjects presence or absence of RI. We found that serum adiponectin level was significantly higher in nondiabetic patients with RI than in nondiabetic subjects without RI; however, there were no statistical differences between the diabetic patients with RI and without RI. In all the subjects, the serum adiponectin level was also higher in 50 individuals with RI than that in 366 subjects without RI. The serum vaspin levels showed no significant differences between the diabetic patients or nondiabetics subjects with RI and without RI. Contrary to adiponectin, the serum vaspin level was lower in 169 patients with T2DM than in 247 individuals without T2DM. Our data suggested that both of T2DM and renal insufficiency were correlated with the serum level of adiponectin. However, the serum vaspin levels showed no significant difference between the individuals with renal insufficiency and without renal insufficiency.

Influence of body mass index on the association of weight changes with mortality in hemodialysis patients

BACKGROUND AND OBJECTIVES

A high body mass index (BMI) is associated with lower mortality in patients undergoing hemodialysis. Short-term weight gains and losses are also related to lower and higher mortality risk, respectively. The implications of weight gain or loss may, however, differ between obese individuals and their nonobese counterparts.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

The Current Management of Secondary Hyperparathyroidism: A Multicenter Observational Study (COSMOS) is an observational study including 6797 European hemodialysis patients recruited between February 2005 and July 2007, with prospective data collection every 6 months for 3 years. Time-dependent Cox proportional hazard regressions assessed the effect of BMI and weight changes on mortality. Analyses were performed after patient stratification according to their starting BMI.

RESULTS

Among 6296 patients with complete data, 1643 died. At study entry, 42% of patients had a normal weight (BMI, 20-25 kg/m(2)), 11% were underweight, 31% were overweight, and 16% were obese (BMI ≥ 30 kg/m(2)). Weight loss or gain (<1% or >1% of body weight) was strongly associated with higher rates of mortality or survival, respectively. After stratification by BMI categories, this was true in nonobese categories and especially in underweight patients. In obese patients, however, the association between weight loss and mortality was attenuated (hazard ratio, 1.28 [95% confidence interval (CI), 0.74 to 2.14]), and no survival benefit of gaining weight was seen (hazard ratio, 0.98 [95% CI, 0.59 to 1.62]).

CONCLUSIONS

Assuming that these weight changes were unintentional, our study brings attention to rapid weight variations as a clinical sign of health monitoring in hemodialysis patients. In addition, a patient's BMI modifies the strength of the association between weight changes with mortality.

Visceral obesity assessed by computed tomography predicts cardiovascular events in chronic kidney disease patients

BACKGROUND AND AIM

Cardiovascular disease is the leading cause of death among patients with chronic kidney disease (CKD). Although there is emerging evidence that excess visceral fat is associated with a cluster of cardiometabolic abnormalities in these patients, the impact of visceral obesity evaluated by a gold-standard method on future outcomes has not been studied. We aimed to investigate whether visceral obesity assessed by computed tomography was able to predict cardiovascular events in CKD patients.

METHODS AND RESULTS

We studied 113 nondialyzed CKD patients [60% men; 31% diabetics; age 55.3 ± 11.3 years; body mass index (BMI) 27.2 ± 5.3 kg/m(2); estimated glomerular filtration rate (GFR) 33.7 ± 13.6 ml/min/1.73 m(2)]. Visceral and subcutaneous abdominal fat were assessed by computed tomography at L4-L5. Visceral to subcutaneous fat ratio >0.55 (highest tertile cut-off) was defined as visceral obesity. Cardiovascular events including acute myocardial infarction, angina, arrhythmia, uncontrolled blood pressure, stroke and cardiac failure were recorded during 24 months. Cardiovascular events were 3-fold higher in patients with visceral obesity than in those without visceral obesity. The Kaplan-Meier analysis indicated that patients with visceral obesity had shorter cardiovascular event-free time than those without visceral obesity (P = 0.021). In the univariate Cox analysis, visceral obesity was associated with higher risk of cardiovascular events (hazard ratio = 3.4; 95% confidence interval = 1.1-10.5; P = 0.03). The prognostic power of visceral obesity for cardiovascular events remained significant after adjustments for sex, age, diabetes, previous cardiovascular disease, smoking, sedentary lifestyle, BMI, GFR, hypertension, dyslipidemia and inflammation.

CONCLUSION

Visceral obesity assessed by computed tomography was a predictor of cardiovascular events in CKD patients.

The adipose tissue as an endocrine organ

During the past 2 decades, results of both basic science and clinical studies have changed the physicians' views about adipocyte pathophysiology. Since leptin was discovered in 1994, white adipose tissue was recognized as an endocrine organ and an important source of biologically active substances with local and/or systemic action called adipokines. Inappropriate secretion of several adipokines by the excessive amount of white adipose tissue seems to participate in the pathogenesis of obesity-related pathologic processes including endothelial dysfunction, inflammation, atherosclerosis, diabetes mellitus, and chronic kidney disease. In this review endocrine action of selected adipokines (mainly leptin and adiponectin) in the context of kidney diseases is discussed. Specifically, the role of these adipokines in malnutrition, chronic kidney disease progression, and pathogenesis of cardiovascular complications is presented.

Visceral fat and coronary artery calcification in patients with chronic kidney disease

BACKGROUND

Abdominal fat is a metabolically active tissue which has been associated with cardiovascular events and death in chronic kidney disease (CKD) patients. We explore here the association between surrogates of abdominal fat and coronary artery calcium score (CACs).

METHODS

Cross-sectional analysis of 232 non-dialysis-dependent CKD patients Stages 3-5 (median age 60 [25th-75th percentile 52-67] years; 60% men). Visceral adipose tissue (VAT) and CACs were assessed by computed tomography. Surrogates of abdominal fat included VAT and waist circumference (WC).

RESULTS

VAT was positively associated with CACs in univariate analysis (ρ = 0.23). Across increasing VAT quartiles, patients were older, more often men and smokers. Although increasing VAT quartiles associated with higher glomerular filtration rate and leptin, better nutritional status (subjective global assessment) as well as larger muscle stores and strength, they were also more insulin resistant (HOMA-IR), dyslipidemic and inflamed (C-reactive protein and white blood cells). In addition, CACs were incrementally higher. Clinically evident coronary artery calcification (CACs ≥ 10 Agatston) was present in 63% of the patients. Both increased visceral fat (odd ratio 1.60 [95% CI 1.23-2.09] per standard deviation increase) and increased WC (1.05 [1.01-1.12] per cm increase), augmented the odds to present calcification. Such associations remained statistically significant after extensive multivariate adjustment for confounders.

CONCLUSIONS

Abdominal fat is associated with coronary artery calcification in non-dialysis dependent CKD patients, supporting its potential role as a cardiovascular risk factor in uremia.

Prevention and treatment of protein energy wasting in chronic kidney disease patients: a consensus statement by the International Society of Renal Nutrition and Metabolism

Protein energy wasting (PEW) is common in patients with chronic kidney disease (CKD) and is associated with adverse clinical outcomes, especially in individuals receiving maintenance dialysis therapy. A multitude of factors can affect the nutritional and metabolic status of CKD patients requiring a combination of therapeutic maneuvers to prevent or reverse protein and energy depletion. These include optimizing dietary nutrient intake, appropriate treatment of metabolic disturbances such as metabolic acidosis, systemic inflammation, and hormonal deficiencies, and prescribing optimized dialytic regimens. In patients where oral dietary intake from regular meals cannot maintain adequate nutritional status, nutritional supplementation, administered orally, enterally, or parenterally, is shown to be effective in replenishing protein and energy stores. In clinical practice, the advantages of oral nutritional supplements include proven efficacy, safety, and compliance. Anabolic strategies such as anabolic steroids, growth hormone, and exercise, in combination with nutritional supplementation or alone, have been shown to improve protein stores and represent potential additional approaches for the treatment of PEW. Appetite stimulants, anti-inflammatory interventions, and newer anabolic agents are emerging as novel therapies. While numerous epidemiological data suggest that an improvement in biomarkers of nutritional status is associated with improved survival, there are no large randomized clinical trials that have tested the effectiveness of nutritional interventions on mortality and morbidity.

The serum vaspin levels are reduced in Japanese chronic hemodialysis patients

Background

Visceral adipose tissue-derived serine proteinase inhibitor (vaspin) is an adipokine identified in genetically obese rats that correlates with insulin resistance and obesity in humans. Recently, we found that 7% of the Japanese population with the minor allele sequence (A) of rs77060950 exhibit higher levels of serum vaspin. We therefore evaluated the serum vaspin levels in Japanese chronic hemodialysis patients.

Methods

Healthy Japanese control volunteers (control; n = 95, 49.9±6.91 years) and Japanese patients undergoing hemodialysis therapy (HD; n = 138, 51.4±10.5 years) were enrolled in this study, and serum samples were subjected to the human vaspin RIA system.

Results

The measurement of the serum vaspin levels demonstrated that a fraction of control subjects (n = 5) and HD patients (n = 11) exhibited much higher levels (> 10 ng/ml; Vaspin_High group), while the rest of the population exhibited lower levels (< 3 ng/ml; Vaspin_Low group). By comparing the patients in the Vaspin_Low group, the serum vaspin levels were found to be significantly higher in the control subjects (0.87±0.24 ng/ml) than in the HD patients (0.32±0.15 ng/ml) (p < 0.0001). In the stepwise regression analyses, the serum creatinine and triglyceride levels were found to be independently and significantly associated with the vaspin concentrations in all subjects.

Conclusions

The creatinine levels are negatively correlated with the serum vaspin levels and were significantly reduced in the Japanese HD patients in the Vaspin_Low group.

The impact of calcineurin inhibitors on insulin sensitivity and insulin secretion: a randomized crossover trial in uraemic patients

AIMS

The calcineurin inhibitors cyclosporine and tacrolimus are implicated in post-transplant complications such as new-onset diabetes after transplantation. The relative contribution of each calcineurin inhibitor to new-onset diabetes after transplantation remains unclear. We sought to compare the impact of cyclosporine and tacrolimus on glucose metabolism in humans.

METHODS

Eight haemodialysis patients received 8-10 days of oral treatment followed by 5-h infusions with cyclosporine, tacrolimus and saline in a randomized, investigator-blind, crossover study. Glucose metabolism and β-cell function was investigated through: a hyperinsulinaemic-euglycaemic clamp, an intravenous glucose tolerance test and insulin concentration time series.

RESULTS

Cyclosporine and tacrolimus decreased insulin sensitivity by 22% (P = 0.02) and 13% (P = 0.048), respectively. The acute insulin response and pulsatile insulin secretion were not significantly affected by the drugs.

CONCLUSION

In conclusion, 8-10 days of treatment with cyclosporine and tacrolimus impairs insulin sensitivity to a similar degree in haemodialysis patients, while acute insulin responses and pulsatile insulin secretion remain unaffected.

A combination of biocompatible peritoneal dialysis solutions and residual renal function, peritoneal transport, and inflammation markers: a randomized clinical trial

BACKGROUND

The benefits of biocompatible peritoneal dialysis (PD) fluids, particularly for residual renal function (RRF), are controversial. Moreover, the clinical effects of a PD regimen consisting of different biocompatible PD fluids have not been fully established.

STUDY DESIGN

Prospective, randomized, controlled, open-label study.

SETTING & PARTICIPANTS

Patients with end-stage kidney disease newly started on continuous ambulatory PD therapy (N = 150).

INTERVENTION

A 12-month intervention with 3 biocompatible PD fluids (a neutral-pH, low glucose degradation product, 1.5% glucose solution; a solution with 1.1% amino acid; and a fluid with 7.5% icodextrin) or conventional PD fluid.

OUTCOMES

The primary outcome was change in RRF and daily urine volume. Secondary outcomes were peritoneal transport and inflammation markers.

MEASUREMENTS

RRF, daily urine volume, serum and dialysate cytokine levels.

RESULTS

RRF(3.24 ± 1.98 vs 2.88 ± 2.43 mL/min/1.73 m(2); P = 0.9) and rate of decline in RRF (-0.76 ± 1.77 vs -0.91 ± 1.92 mL/min/1.73 m(2) per year; P = 0.6) did not differ between the biocompatible- and conventional-PD-fluid groups. However, patients using the biocompatible PD fluids had better preservation of daily urine volume (959 ± 515 vs 798 ± 615 mL/d in the conventional group, P = 0.02 by comparison of difference in overall change by repeated-measures analysis of variance). Their dialysate-plasma creatinine ratio at 4 hours was higher at 12 months (0.78 ± 0.13 vs 0.68 ± 0.12; P = 0.01 for comparison of the difference in overall change by repeated-measures analysis of variance). They also had significantly higher serum levels of adiponectin and overnight spent dialysate levels of cancer antigen 125, adiponectin, and interleukin 6 (IL-6). No differences between the 2 groups were observed for serum C-reactive protein and IL-6 levels.

LIMITATIONS

Unblinded, relatively short follow-up; no formal sample-size calculations.

CONCLUSIONS

Use of a combination of 3 biocompatible PD fluids for 12 months compared with conventional PD fluid did not affect RRF, but was associated with better preservation of daily urine volume. The biocompatible PD fluids also lead to changes in small-solute transport and an increase in dialysate cancer antigen 125, IL-6, adiponectin, and systemic adiponectin levels, but have no effect on systemic inflammatory response. The clinical significance of these changes, while of great interest, remains to be determined by further studies.

Inverse relationship between the inflammatory marker pentraxin-3, fat body mass, and abdominal obesity in end-stage renal disease

BACKGROUND AND OBJECTIVES

Pentraxin-3 (PTX3) belongs to the same pentraxin superfamily of acute-phase reactants as C-reactive protein (CRP). Abdominal fat accumulation in ESRD is considered a chronic inflammatory state, but the relationship of PTX3 to this phenomenon is unknown. This study assesses plausible associations between PTX3 and surrogates of fat mass deposits in dialysis patients.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Circulating levels of PTX3, CRP, and IL-6 were cross-sectionally analyzed in relation to anthropometric and nutritional surrogate markers of fat tissue in two cohorts comprising 156 prevalent hemodialysis (HD) and 216 incident dialysis patients.

RESULTS

In both cohorts, PTX3 was negatively associated with body mass index (BMI) and fat body mass index (FBMI) derived from anthropometrics and leptin, whereas there was a positive association with adiponectin. In prevalent HD patients, those with larger waist circumference (above gender-specific median values) had lower PTX3, higher CRP, and higher IL-6 levels. This was also true in multivariate analyses. In both cohorts, multivariate regression analyses showed that PTX3 was negatively and CRP (or IL-6) was positively associated with FBMI.

CONCLUSIONS

Although CRP and IL-6 were directly associated with body fat, PTX3 levels showed negative correlations with surrogates of adipose tissue in two independent cohorts of ESRD patients. Understanding the underlying reasons behind these opposite associations may have clinical relevance given the survival advantage described for obese patients on dialysis.

Differential effect of baseline adiponectin on all-cause mortality in hemodialysis patients depending on initial body mass index. Long-term follow-up data of 4.5 years

OBJECTIVES

We sought to investigate the interaction of adiponectin levels and body mass index (BMI) for predicting all-cause mortality in a cohort of hemodialysis (HD) patients.

DESIGN

Longitudinal, observational cohort study.

SETTING

HD unit.

SUBJECTS

Sixty patients (mean age: 64 ± 13 years, 39 men) with end-stage renal disease on maintenance HD followed up for 4.5 years represented the prospective study cohort.

INTERVENTION

Associations between baseline plasma adiponectin levels and initial BMI with all-cause mortality were assessed taking into account the assumption of nonlinear correlations. The association between adiponectin, BMI, and serum levels of interleukin-10 (IL-10) and interleukin-6 (IL-6) with survival was determined cross-sectionally.

MAIN OUTCOME MEASURE

All-cause mortality.

RESULTS

Nonlinear survival modeling showed that there was a U-shaped association of BMI with all-cause mortality, whereas there was an inverse U-shaped association for plasma adiponectin levels. Using a BMI of 24 kg/m(2) as a cutoff, an interaction effect of BMI on the association between adiponectin and mortality was observed (P = .045). In participants with BMI ≥ 24 kg/m(2), each 15 μg/mL increase in plasma adiponectin levels was associated with a decreased hazard of death (hazard ratio: 0.57, 95% CI: 0.32 to 0.99) in unadjusted analysis. In HD patients with BMI < 24 kg/m(2), no significant association was observed between adiponectin and mortality (P = .989). Cross-sectional analysis showed that in the subgroup of patients in whom the protective effect of adiponectin was observed (BMI ≥ 24 kg/m(2)), a positive linear association existed between adiponectin and IL-10 levels (r = 0.345, P = .027) as well as a negative association with IL-6 levels (r = -0.322, P = .040). No association was observed in patients with BMI < 24 kg/m(2), neither with IL-10 nor with IL-6.

CONCLUSIONS

Obesity possibly modifies the effect of adiponectin on all-cause mortality in HD patients, thus explaining the published conflicting results in recent literature regarding the association of plasma adiponectin levels and mortality in chronic kidney disease patients.

Annual variation in body fat is associated with systemic inflammation in chronic kidney disease patients Stages 3 and 4: a longitudinal study

BACKGROUND

In dialysis patients, cross-sectional studies show that total and abdominal body fat associate with inflammatory markers. Whether this is true in earlier disease stages is unknown. We evaluated the cross-sectional and longitudinal (12-month interval) association between body fat markers and C-reactive protein (CRP) in pre-dialysis chronic kidney disease (CKD) patients.

METHODS

We studied, over a period of 1 year, clinically stable CKD patients at Stages 3-4 who were under treatment in a single outpatient clinic. Fifty-seven patients were included and 44 concluded the observational period [males: 66%; age: 62.9±13.9 years; body mass index (BMI): 25.5±5.1 kg/m2; estimated glomerular filtration rate (eGFR): 34±12.3 mL/min/1.73 m2]. Total body fat (skinfold thicknesses), waist circumference (WC), laboratory measurements (serum creatinine, total cholesterol, albumin, high-sensitivity CRP and leptin) and food intake (24-h food recall) were assessed at baseline and after 12±2 months.

RESULTS

Most patients had anthropometric parameters in the range of overweight/obesity and none had signs of protein-energy wasting. In univariate analysis, changes (delta: end-baseline) in CRP were associated (P<0.05) with changes in BMI (r=0.39) and WC (r=0.33). In multiple regression analysis, these associations remained significant (P<0.05) even after adjusted by potential confounders (sex, diabetes, baseline age and eGFR).

CONCLUSIONS

During a follow-up of 12 months, changes in BMI and WC were directly associated with changes in CRP. Our results support the concept that interventions aimed at reducing weight and/or abdominal adiposity in pre-dialysis CKD patients may also translate into reduced systemic inflammation.

Wasting and sudden cardiac death in hemodialysis patients: a post hoc analysis of 4D (Die Deutsche Diabetes Dialyse Studie)

BACKGROUND

Wasting is common in hemodialysis patients and often is accompanied by cardiovascular disease and inflammation. The cardiovascular risk profile meaningfully changes with the progression of kidney disease, and little is known about the impact of wasting on specific clinical outcomes. This study examined the effects of wasting on the various components of cardiovascular outcome and deaths caused by infection in hemodialysis patients.

STUDY DESIGN

Prospective cohort study.

SETTING & PARTICIPANTS

1,255 hemodialysis patients from 178 centers participating in Die Deutsche Diabetes Dialyse Studie (4D) in 1998-2004.

PREDICTOR

Moderate wasting was defined as body mass index, albumin, and creatinine values less than the median (26.7 kg/m(2), 3.8 g/dL, and 6.8 mg/dL, respectively) and C-reactive protein level less than the median (5 mg/L) at baseline. Severe wasting was defined as body mass index, albumin, and creatinine levels less than the median and C-reactive protein level greater than the median at baseline.

OUTCOMES & MEASUREMENTS

Risks of sudden cardiac death (SCD), myocardial infarction (MI), stroke, combined cardiovascular events, deaths due to infection, and all-cause mortality were determined using Cox regression analyses during a median of 4 years of follow-up.

RESULTS

196 patients had wasting (severe, n = 109; and moderate, n = 87). Overall, 617 patients died (160 of SCD and 128 of infectious deaths). Furthermore, 469 patients experienced a cardiovascular event, with MI and stroke occurring in 200 and 103 patients, respectively. Compared with patients without wasting (n = 1,059), patients with severe wasting had significantly increased risks of SCD (adjusted HR, 1.8; 95% CI, 1.1-3.1), all-cause mortality (adjusted HR, 1.8; 95% CI, 1.4-2.4), and deaths due to infection (adjusted HR, 2.3; 95% CI, 1.2-4.3). In contrast, MI was not affected. The increased risk of cardiovascular events (adjusted HR, 1.5; 95% CI, 1.0-2.1) was explained mainly by the effect of wasting on SCD.

LIMITATIONS

Selective patient cohort.

CONCLUSIONS

Wasting was associated strongly with SCD, but not MI, in diabetic hemodialysis patients. Nonatherosclerotic cardiac disease potentially has a major role to account for the increased cardiovascular events in patients with wasting, suggesting the need for novel treatment strategies.

Protein-energy wasting and mortality in chronic kidney disease

Protein-energy wasting (PEW) is common in patients with chronic kidney disease (CKD) and is associated with an increased death risk from cardiovascular diseases. However, while even minor renal dysfunction is an independent predictor of adverse cardiovascular prognosis, PEW becomes clinically manifest at an advanced stage, early before or during the dialytic stage. Mechanisms causing loss of muscle protein and fat are complex and not always associated with anorexia, but are linked to several abnormalities that stimulate protein degradation and/or decrease protein synthesis. In addition, data from experimental CKD indicate that uremia specifically blunts the regenerative potential in skeletal muscle, by acting on muscle stem cells. In this discussion recent findings regarding the mechanisms responsible for malnutrition and the increase in cardiovascular risk in CKD patients are discussed. During the course of CKD, the loss of kidney excretory and metabolic functions proceed together with the activation of pathways of endothelial damage, inflammation, acidosis, alterations in insulin signaling and anorexia which are likely to orchestrate net protein catabolism and the PEW syndrome.

Expression of osteoprotegerin in human fat tissue; implications for chronic kidney disease

BACKGROUND

Premature vascular calcification (or rather ossification) significantly contributes to morbidity and mortality in patients with chronic kidney disease stage 5 (CKD-5) and is linked to dysregulation of bone remodelling proteins. Recent evidence of a cross-talk between bone and fat tissue urged us to investigate whether the calcification/ossification-associated factors osteoprotegerin (OPG) and alpha-2-HS-glycoprotein (AHSG) are expressed in human uremic subcutaneous adipose tissue (SAT) and if the expression differs from nonuremic SAT.

MATERIALS AND METHODS

Abdominal SAT biopsies were obtained from 38 patients with CKD-5 [16 women, 58 (22-73) years old] during the surgical insertion of a peritoneal dialysis catheter and 20 controls [11 females, 56 (40-77) years old] undergoing elective hernia repair or laparoscopic cholecystectomy. Real-time polymerase chain reaction (PCR) quantifications were performed followed by immunohistochemical staining and serum protein concentration measurements. Relative mRNA expression and protein concentrations were evaluated together with clinical parameters. An additional 59 patients with CKD-5 were included for replication of statistical analyses.

RESULTS

OPG but not AHSG mRNAs were detected in SAT, which were also positively immunolabelled for OPG. OPG mRNA levels were reduced (P = ·0001) and serum OPG concentrations were elevated (P < 0·0001), both about twofold, in patients compared to controls. Circulating OPG increased in proportion to BMI.

CONCLUSIONS

Human SAT expresses OPG but not AHSG, and OPG expression is reduced in patients with CKD-5 when compared to controls, despite increased circulating protein levels.

Increased expression of pro-inflammatory genes in abdominal subcutaneous fat in advanced chronic kidney disease patients

OBJECTIVES

Low-grade systemic inflammation, oxidative stress and peripheral insulin resistance are intimately associated and contribute to the increased risk of cardiovascular complications in advanced chronic kidney disease (CKD). Because altered adipose tissue activities have previously been linked to pathophysiological processes in various inflammatory and metabolic diseases we hypothesized that the uraemic milieu in patients with CKD may interact with the adipose tissue, provoking an unfavourable shift in its transcriptional output.

DESIGN

Twenty-one adipokine mRNAs were quantified in abdominal subcutaneous adipose tissue (SAT) biopsies and serum/plasma concentrations of inflammatory markers and related protein products were measured.

SETTING

The study was conducted at the Karolinska University Hospital, Huddinge, and Karolinska Institutet, Stockholm, Sweden.

SUBJECTS

Thirty-seven patients with CKD [15 women, median 58 (interquartile range 49-65) years] and nine nonuraemic individuals [four women, age 62 (45-64) years] were recruited prior to initiation of peritoneal dialysis catheter insertion or elective hernia repair/laparoscopic cholecystectomy, respectively.

RESULTS

Even after correction for body mass index, SAT from patients showed a significant upregulation of inflammatory pathway genes interleukin 6 (3.0-fold, P=0.0002) and suppressor of cytokine signalling 3 (2.5-fold, P=0.01), as well as downregulation of leptin (2.0-fold, P=0.03) and the oxidative stress genes uncoupling protein 2 (1.5-fold, P=0.03) and cytochrome b-245, alpha polypeptide (1.5-fold, P=0.005), in relation to controls.

CONCLUSIONS

These gene expression differences suggest that inflammatory and oxidative stress activities may be important features of the intrinsic properties of uraemic adipose tissue, which may have significant effects on the uraemic phenotype.

Rosiglitazone does not improve vascular function in subjects with chronic kidney disease

BACKGROUND

Thiazolidinediones such as rosiglitazone (RSG) are insulin-sensitizing agents, which may improve inflammation and vascular function, and thus potentially lower cardiovascular risk in patients with chronic kidney disease (CKD). However, there is growing concern about the adverse cardiovascular effects of RSG in diabetic patients without CKD, and the data in patients with CKD remain conflicting. This study examines the effect of RSG on vascular function in patients with CKD.

METHODS

A randomized, double-blind placebo-controlled study comparing RSG 4 mg daily (n = 35) with placebo (n = 35) for 8 weeks was performed in CKD subjects. Primary outcome measures were flow-mediated dilatation (FMD), systemic arterial compliance (SAC) and augmentation index (AIx). Secondary outcomes included glyceryl trinitrate-mediated dilatation (GTN-MD), pulse-wave velocity (PWV), lipids, blood pressure, homoeostasis model assessment (HOMA), adiponectin, high-sensitivity C-reactive protein (hs-CRP) and high-sensitivity interleukin 6 (hs-IL-6) and in vivo marker of endothelial function [von Willebrand Factor (vWF)].

RESULTS

RSG lowered HOMA score [RSG geometric mean 1.7 (95% confidence interval 1.3-2.3); placebo 1.9 (1.4-2.5), P = 0.04], hs-CRP [RSG 1.2 (0.9-1.7) mg/L; placebo 1.6 (1.2-2.3), P = 0.04] and vWF [RSG mean 126.1 ± SD 45.7%; placebo 132.7 ± 41.7, P = 0.01] but not hs-IL-6. RSG did not significantly change arterial function (FMD, GTN-MD, SAC), arterial stiffness (AIx, PWV) or blood pressure. RSG increased triglyceride concentration [RSG 1.8 (1.3-1.9) mmol/L; placebo 1.5 (1.3-1.9), P = 0.01] without affecting other lipid and lipoprotein concentrations.

CONCLUSION

Short-term RSG therapy reduced insulin resistance, in vivo markers of inflammation and abnormal endothelial function but had no effect on arterial function and stiffness in patients with CKD.

Waist circumference modifies the relationship between the adipose tissue cytokines leptin and adiponectin and all-cause and cardiovascular mortality in haemodialysis patients

BACKGROUND

the relationships between the adipose tissue cytokines leptin and adiponectin (ADPN) and clinical outcomes have not been well studied in haemodialysis (HD) patients and remain highly controversial. As central obesity is an important modifier of the effect of various risk factors for clinical outcomes, we tested the hypothesis that waist circumference (WC) modifies the link between these cytokines and both overall and cardiovascular death in HD patients.

METHODS

a total of 537 HD patients participated in a prospective cohort study.

RESULTS

leptin and ADPN were inversely related to each other and robustly associated with WC (P < 0.001). During follow-up (average 29 months, range 1-47 months) 182 patients died, including 115 from cardiovascular causes. In analyses adjusting for potential confounders, there were strong interactions between leptin and WC in relationship to both all-cause (P < 0.001) and cardiovascular death (P = 0.002). Accordingly, a fixed excess of leptin signalled a gradually increasing risk for all-cause and cardiovascular mortality in patients with a large WC but an opposite effect in those with a relatively small WC. An interaction between ADPN and WC for all-cause (P = 0.01) and cardiovascular mortality (P = 0.01) emerged only in models excluding the leptin-WC interaction, suggesting that these adipokines share a common pathway leading to adverse clinical events in HD patients.

CONCLUSIONS

the predictive value of leptin and ADPN for all-cause and cardiovascular death in HD patients appears to be critically dependent on WC. These findings support the hypothesis that disturbances in adipokine levels are involved in adverse clinical outcomes in HD patients with abdominal obesity.

Endogenous testosterone and mortality in male hemodialysis patients: is it the result of aging?

BACKGROUND AND OBJECTIVES

Low serum testosterone levels in hemodialysis (HD) patients have recently been associated with cardiovascular risk factors and increased mortality. To confirm this observation, we investigated the predictive role of serum total testosterone levels on mortality in a large group of male HD patients from Turkey.

DESIGN, SETTINGS, PARTICIPANTS, & MEASUREMENTS

A total of 420 prevalent male HD patients were sampled in March 2005 and followed up for all-cause mortality. Serum total testosterone levels were measured by ELISA at baseline and studied in relation to mortality and cardiovascular risk profile.

RESULTS

Mean testosterone level was 8.69 ± 4.10 (0.17 to 27.40) nmol/L. A large proportion of patients (66%) had testosterone deficiency (<10 nmol/L). In univariate analysis, serum testosterone levels were positively correlated with creatinine and inversely correlated with age, body mass index, and lipid parameters. During an average follow-up of 32 months, 104 (24.8%) patients died. The overall survival rate was significantly lower in patients within the low testosterone tertile (<6.8 nmol/L) compared with those within the high tertile (>10.1 nmol/L; 64 versus 81%; P = 0.004). A 1-nmol/L increase in serum testosterone level was associated with a 7% decrease in overall mortality (hazard ratio 0.93; 95% confidence interval 0.89 to 0.98; P = 0.01); however, this association was dependent on age and other risk factors in adjusted Cox regression analyses.

CONCLUSIONS

Testosterone deficiency is common in male HD patients. Although testosterone levels, per se, predicted mortality in this population, this association was largely dependent on age.