Peter Stenvinkel

Impact of inflammation on epigenetic DNA methylation - : a novel risk factor for cardiovascular disease?

Objective.  The lifespan of dialysis patients is as short as in patients with metastatic cancer disease, mainly due to cardiovascular disease (CVD). DNA methylation is an important cellular mechanism modulating gene expression associated with ageing, inflammation and atherosclerotic processes.

Comparative Associations of Muscle Mass and Muscle Strength with Mortality in Dialysis Patients

BACKGROUND AND OBJECTIVES Reduced muscle mass and strength are prevalent conditions in dialysis patients. However, muscle strength and muscle mass are not congruent; muscle strength can diminish even though muscle mass is maintained or increased. This study addresses phenotype and mortality associations of these muscle dysfunction entities alone or in combination (i.e., concurrent loss of muscle mass and strength/mobility, here defined as sarcopenia). DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS This study included 330 incident dialysis patients (203 men, mean age 53±13 years, and mean GFR 7±2 ml/min per 1.73 m(2)) recruited between 1994 and 2010 and followed prospectively for up to 5 years. Low muscle mass (by dual-energy x-ray absorptiometry appendicular mass index) and low muscle strength (by handgrip) were defined against young reference populations according to the European Working Group on Sarcopenia in Older People. RESULTS Whereas 20% of patients had sarcopenia, low muscle mass and low muscle strength alone were observed in a further 24% and 15% of patients, respectively. Old age, comorbidities, protein-energy wasting, physical inactivity, low albumin, and inflammation associated with low muscle strength, but not with low muscle mass (multivariate ANOVA interactions). During follow-up, 95 patients (29%) died and both conditions associated with mortality as separate entities. When combined, individuals with low muscle mass alone were not at increased risk of mortality (adjusted hazard ratio [HR], 1.23; 95% confidence interval [95% CI], 0.56 to 2.67). Individuals with low muscle strength were at increased risk, irrespective of their muscle stores being appropriate (HR, 1.98; 95% CI, 1.01 to 3.87) or low (HR, 1.93; 95% CI, 1.01 to 3.71). CONCLUSIONS Low muscle strength was more strongly associated with aging, protein-energy wasting, physical inactivity, inflammation, and mortality than low muscle mass. Assessment of muscle functionality may provide additional diagnostic and prognostic information to muscle-mass evaluation.

Prevalence and clinical implications of testosterone deficiency in men with end-stage renal disease

BACKGROUND Abnormally low serum testosterone levels were recently associated with an increased mortality risk in male dialysis patients. However, the prevalence of testosterone deficiency in end-stage renal disease (ESRD) is not well defined. We hereby explore the prevalence and correlates of clinical testosterone deficiency in a large cohort of ESRD male patients. METHODS Two hundred and sixty ESRD men [median age 59 (25th-75th percentile 48-67)  years] were included. Testosterone concentration and testosterone deficiency (<10 nmol/L) were studied in relation to clinically evident cardiovascular disease and markers of inflammation at baseline as well as deaths registered during the following 36 months. RESULTS Testosterone deficiency was present in 44% of the patients, while 33% showed testosterone insufficiency (10-14 nmol/L), and only 23% had normal testosterone values (>14 nmol/L). Testosterone was strongly and inversely correlated to inflammatory markers (CRP, IL-6 and fibrinogen), even after correction for age and sex hormone-binding globulin. In a crude spline curve, low testosterone concentrations were associated with worse outcome. A clinical condition of testosterone deficiency was independently associated with cardiovascular co-morbidity [odds ratio (OR) 2.51; 95% confidence interval (CI) 1.32-4.76] and death (OR 2.00; 95% CI 1.01-3.97) in logistic regression analyses. CONCLUSIONS Testosterone deficiency is a common finding among male ESRD patients, and it is independently associated with inflammation, cardiovascular co-morbidity and outcome. Future studies are needed to determine the potential adverse effects of male hypogonadism in ESRD and the possibility of improving risk profile, quality of life, and ultimately outcome with testosterone supplementation in these patients.

Prolactin Levels, Endothelial Dysfunction, and the Risk of Cardiovascular Events and Mortality in Patients with CKD

BACKGROUND AND OBJECTIVES Both prolactin clearance and production are altered in CKD. In nonrenal populations, emerging evidence suggests that prolactin participates in the atherosclerotic process. Given the elevated cardiovascular risk of CKD, this study examined links between prolactinemia, vascular derangements, and outcomes. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS This observational study was conducted in two cohorts: one with 457 nondialyzed CKD patients (mean age 52±12 years; 229 men) with measurements of flow-mediated dilation (FMD) and carotid intima-media thickness and one with 173 hemodialysis patients (65±12 years; 111 men) with measurements of pulse wave velocity (PWV). Patients were followed for cardiovascular events (n=146, nondialyzed cohort) or death (n=79, hemodialysis cohort). RESULTS Prolactin levels increased along with reduced kidney function. Prolactin significantly and independently contributed to explain the variance of both FMD (in nondialyzed patients) and PWV (in hemodialysis patients), but not intima-media thickness. In Cox analyses, the risk of cardiovascular events in nondialyzed patients increased by 27% (hazard ratio [HR], 1.27; 95% confidence interval [95% CI], 1.17-1.38) for each 10 ng/ml increment of prolactin. Similarly, the risk for all-cause and cardiovascular mortality in hemodialysis patients increased by 12% (HR, 1.12; 95% CI, 1.06-1.17) and 15% (HR, 1.15; 95% CI, 1.08-1.21), respectively. This was true after multivariate adjustment for confounders and after adjustment within the purported causal pathway (FMD or PWV). CONCLUSIONS Prolactin levels directly associated with endothelial dysfunction/stiffness and with increased risk of cardiovascular events and mortality in two independent cohorts of CKD patients.

Visfatin is increased in chronic kidney disease patients with poor appetite and correlates negatively with fasting serum amino acids and triglyceride levels

OBJECTIVE Anorexia is a common complication of chronic kidney disease (CKD), while novel animal and human data suggest a role for visfatin in regulating feeding behavior. We hypothesized that increased visfatin levels in CKD patients may be involved in the regulation of appetite and nutrient homeostasis. METHODS This is a cross-sectional study where circulating visfatin levels were analysed in 246 incident CKD stage 5 patients starting dialysis therapy. The associations between visfatin (enzyme-linked immunosorbent assay, ELISA) and anthropometric and biochemical nutritional status, self-reported appetite, fasting serum amino acids (high-performance liquid chromatography) and circulating cytokine levels (ELISAs) were assessed. We also performed genotyping (Pyrosequencing(R)) of two polymorphisms (rs1319501 and rs9770242) in the visfatin gene. RESULTS Serum visfatin concentrations were not associated with either body mass index or serum leptin. Across groups with worsening appetite, median visfatin levels were incrementally higher (P < 0.05). With increasing visfatin tertiles, patients proved to be more often anorectic (P < 0.05) and to have incrementally lower serum albumin, cholesterol and triglycerides as well as lower essential and non-essential serum amino acids (P < 0.05 for all). A polymorphism in the visfatin gene was associated with increased circulating visfatin levels and, at the same time, a higher prevalence of poor appetite (P < 0.05 for both). CONCLUSION Our study suggests novel links between visfatin and anorexia in CKD patients. Based on recent studies, we speculate that high visfatin in CKD patients may constitute a counter-regulatory response to central visfatin resistance in uremia. Future studies should examine a putative role of visfatin as a regulator of nutrient homeostasis in uremia.

Biomarkers of Cardiovascular Disease and Mortality Risk in Patients with Advanced CKD

BACKGROUND AND OBJECTIVES The high risk of cardiovascular disease (CVD) and premature death in patients with CKD associates with a plethora of elevated circulating biomarkers that may reflect distinct signaling pathways or simply, are epiphenomena of CKD. We compared the predictive strength of 12 biomarkers analyzed concomitantly in patients with stage 5 CKD. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS From 1994 to 2014, 543 patients with stage 5 CKD (median age =56 years old; 63% men; 199 patients had CVD) took part in our study on malnutrition, inflammation, and CVD in incident dialysis patients. Circulating levels of albumin, ferritin, high-sensitivity C-reactive protein (hsCRP), IGF-1, IL-6, orosomucoid, troponin T (TnT), TNF, soluble intracellular adhesion molecule, soluble vascular cellular adhesion molecule 1 (sVCAM-1), and platelet and white blood cell (WBC) counts were analyzed as predictors of the presence of clinically overt CVD at baseline, protein-energy wasting (PEW), and subsequent all-cause mortality. During follow-up for a median of 28 months, there were 149 deaths, 81 of which were caused by CVD. RESULTS Most biomarkers were elevated compared with reference values and--except for albumin, ferritin, and IGF-1-higher in patients with CVD. In receiver operating characteristic analysis, age, IL-6, TnT, hsCRP, and IGF-1 were classifiers of baseline CVD and predictors of all-cause mortality. In addition to age, diabetes mellitus, smoking (for CVD), and PEW, only IL-6, relative risk (RR) 1.10 and 95% confidence interval ([95% CI], 1.02 to 1.19), sVCAM-1 RR 1.09 (95% CI, 1.01 to 1.17), and serum albumin RR 0.89 (95% CI, 0.83 to 0.95) associated with baseline CVD, and only WBC, hazard ratio (HR) 1.94 (95% CI, 1.34 to 2.82), IL-6 HR 1.79 (95% CI, 1.20 to 2.67), and TNF HR 0.65 (95% CI, 0.44 to 0.97) predicted all-cause mortality. CONCLUSIONS In addition to age and comorbidities, only IL-6, sVCAM-1, and albumin could-independently of other biomarkers-classify clinical CVD, and only IL-6, WBC, and TNF could-independently of other biomarkers-predict all-cause mortality risk. These data underscore the robustness of IL-6 as a classifier of clinically overt CVD and predictor of all-cause mortality in patients with stage 5 CKD.

POOR NUTRITIONAL STATUS AND INFLAMMATION: Novel Approaches in an Integrated Therapy of Inflammatory-Associated Wasting in End-Stage Renal Disease

It is increasingly apparent that end‐stage renal disease (ESRD) patients carry an inflammatory burden, which may play a pivotal role in the evolution of not only wasting, but also the massive increase in the relative risk of cardiovascular disease (CVD). Thus wasting is strongly associated with a persistent systemic inflammatory response, CVD, and impaired patient survival in end‐stage renal disease (ESRD), as well as in other chronic diseases. Evidence suggests that a facilitative interaction between inflammatory cytokines and other factors such as poor appetite, comorbidity, acidosis, anemia, and hormonal derangements may cause wasting in this patient group. Clearly, isolated interventions in the form of nutritional energy and protein supplementation have seldom proven to be very effective in improving nutritional status and outcome in ESRD patients, presumably because of the need to attack other causative factors. Therefore, new treatment strategies must be evaluated. Strategies such as multiple appetite stimulants, various “anti‐inflammatory diets,” and new potentially useful anti‐inflammatory pharmacologic agents may be tested alone, or in combination, to evaluate if these new therapeutic modalities can improve the outcome of ESRD patients. As the etiology of wasting in ESRD is multifactorial, we propose that its treatment must include not one, but a number of concomitant measures to provide an integrated therapy against this devastating complication.

Is Fetuin-A/α2-Heremans-Schmid Glycoprotein Associated with the Metabolic Syndrome in Patients with Chronic Kidney Disease?

Introduction: Components of the metabolic syndrome are highly prevalent in chronic kidney disease (CKD) patients – some of which paradoxically appear to predict an improved outcome in this population. We hypothesized that the circulating calcification inhibitor fetuin-A/AHSG, which is also a natural inhibitor of the tyrosine kinase insulin receptor, could be one factor explaining the association between increased fat mass and a survival advantage in CKD and thus conducted an explorational study to provide preliminary data to support further research into this hypothesis. Patients and Methods: In a cross-sectional study, we evaluated 198 CKD stage 5 patients (GFR 6.8 ± 0.2 ml/min; 62% males, mean age 52 ± 1 years) close to the start of renal replacement therapy. We studied circulating AHSG (ELISA) and two common functional AHSG gene polymorphisms (at amino acids Thr248Met (C-T) and Thr256Ser (C-G) using Pyrosequencing®) and related these to multiple components of the metabolic syndrome. Results: Median circulating AHSG was lower (p < 0.01) in type-2 (0.22 g/l) and type-1 (0.16 g/l) diabetics as compared to non-diabetic CKD-5 patients (0.24 g/l). AHSG correlated with both total and truncal fat mass in type-2 diabetics (rho 0.37 and 0.39; p < 0.001, respectively), but not in type-1 diabetics or non-diabetics. Both SNPs significantly influenced circulating levels of AHSG, and were also associated with significant differences in serum triglycerides and HDL cholesterol. Furthermore, there were significant differences in the prevalence of metabolic syndrome criteria between the AHSG Thr256Ser (C-G) genotype groups, with a more atherogenic lipid profile in AHSG high producers (Thr/Thr homozygotes). In multivariate analysis, the association between circulating AHSG and fat mass remained significant also after adjustment for age, gender, inflammation (CRP >10 mg/l), and AHSG genotype. Conclusions: The present, explorational, study supports further, mechanistic, studies into a physiological link between AHSG and body fat mass in patients with CKD. As we observed an association between higher fat mass and elevated AHSG levels, these preliminary results may form the basis of further study to establish if the observed associations may be one reason why obesity has been reported to constitute a survival advantage in CKD.

Interleukin-1 gene cluster polymorphisms are associated with nutritional status and inflammation in patients with end-stage renal disease.

Background: Wasting and inflammation are two common risk factors for death in patients with end-stage renal disease (ESRD). Interleukin-1β (IL-1β) and its receptor antagonist (IL-1Ra) may play a pivotal role in the pathogenesis of wasting and inflammation. Methods: To investigate effects of the IL-1 gene cluster polymorphisms on wasting and inflammation, we studied 189 ESRD patients (52 ± 12 years, 62% males) close to the start of renal replacement therapy. 205 healthy volunteers served as controls. We analyzed the IL-1B –511C/T, –31C/T, and +3954C/T polymorphisms as well as a variable number of a tandem repeat (VNTR) in IL-1RN. Nutritional parameters included serum albumin level, subjective global nutritional assessment (SGA), and body composition evaluated by dual-energy X-ray absorptiometry (DXA). We used serum high-sensitivity C-reactive protein (hsCRP) as a marker of inflammation. Results: Wasting (SGA >1) was present in 31%, whereas inflammation (CRP ≧10 mg/l) was present in 36% of the patients. The male carriers of the –511T/T and –31C/C genotypes had a lower prevalence of wasting (p < 0.05), higher body mass index (BMI) (p < 0.05), and higher lean body mass (LBM) (p < 0.01). In a stepwise multiple regression model, age (p < 0.05), BMI (p < 0.01) and the IL-1B –511 genotype (p < 0.01) were independently associated with LBM. The carriers of the +3954T allele had a lower prevalence of inflammation (p < 0.05) and lower serum hsCRP (p < 0.05). The VNTR in IL-1RN was not associated with any markers. Conclusion: The investigated IL-1 gene cluster polymorphisms were associated with nutritional status and inflammation in ESRD patients, but marked differences were found between the genders. These polymorphisms could have prognostic utility for predicting wasting and inflammation in ESRD patients.

Lipoprotein Lipase 1595 C/G and Hepatic Lipase –480 C/T Polymorphisms – Impact on Lipid Profile in Incident Dialysis Patients

Background: Dyslipidemia is a common complication of chronic kidney disease. Lipoprotein lipase (LPL) 1595 C/G and hepatic lipase (HL) –480 C/T single nucleotide polymorphisms (SNPs) influence lipid profile and predisposition for cardiovascular disease in the general population. The present study was undertaken to clarify the impact of the two polymorphisms on lipid parameters and cardiovascular risk in incident dialysis patients. Methods: LPL 1595 C/G and HL –480 C/T SNPs were evaluated in 293 chronic kidney disease patients close to dialysis initiation. Associations with lipid parameters, presence of cardiovascular disease, and survival were assessed. Results: LPL 1595 C/G SNP was associated with significantly lower triglyceride levels [1.55 (1.00–2.20) vs. 1.90 (1.40–2.48) mM; p < 0.01], while HL –480 C/T polymorphism was associated with increased high density lipoprotein cholesterol concentration [1.30 (1.00–1.60) vs. 1.10 (0.90–1.40) mM; p < 0.05]. Neither of the polymorphisms showed any relationship with patient survival. Conclusions: LPL 1595 C/G and HL –480 C/T polymorphisms affect lipid profile in incident dialysis patients.