Epigenetic clocks indicate that kidney transplantation and not dialysis mitigate the effects of renal ageing.

Background: Chronic kidney disease (CKD) is an age-related disease that displays multiple features of accelerated ageing. It is currently unclear whether the two treatment options for end-stage kidney disease (dialysis and kidney transplantation [KT]) ameliorate the accelerated uremic ageing process.

Methods: Data on clinical variables and blood DNA methylation (DNAm) from CKD stage G3-G5 patients were used to estimate biological age based on blood biomarkers (phenotypic age [PA], n = 333), skin autofluorescence (SAF age, n = 199) and DNAm (Horvath, Hannum and PhenoAge clocks, n = 47).

Longitudinal genome-wide DNA methylation changes in response to kidney failure replacement therapy.

Chronic kidney disease (CKD) is an emerging public health priority associated with high mortality rates and demanding treatment regimens, including life-style changes, medications or even dialysis or renal transplantation. Unavoidably, the uremic milieu disturbs homeostatic processes such as DNA methylation and other vital gene regulatory mechanisms. Here, we aimed to investigate how dialysis or kidney transplantation modifies the epigenome-wide methylation signature over 12 months of treatment.

Current epigenetic aspects the clinical kidney researcher should embrace.

Chronic kidney disease (CKD), affecting 10-12% of the world's adult population, is associated with a considerably elevated risk of serious comorbidities, in particular, premature vascular disease and death. Although a wide spectrum of causative factors has been identified and/or suggested, there is still a large gap of knowledge regarding the underlying mechanisms and the complexity of the CKD phenotype. Epigenetic factors, which calibrate the genetic code, are emerging as important players in the CKD-associated pathophysiology.

expression is associated with vascular progeria in chronic kidney disease.

Patients with chronic kidney disease (CKD) display a progeric vascular phenotype linked to apoptosis, cellular senescence and osteogenic transformation. This has proven intractable to modelling appropriately in model organisms. We have therefore investigated this directly in man, using for the first time validated cellular biomarkers of ageing ( SA-β-Gal) in arterial biopsies from 61 CKD patients undergoing living donor renal transplantation.

Increased Telomere Attrition After Renal Transplantation-Impact of Antimetabolite Therapy.

Background: The uremic milieu exposes chronic kidney disease (CKD) patients to premature ageing processes. The impact of renal replacement therapy (dialysis and renal transplantation [RTx]) or immunosuppressive treatment regimens on ageing biomarkers has scarcely been studied.

Methods: In this study telomere length in whole blood cells was measured in 49 dialysis patients and 47 RTx patients close to therapy initiation and again after 12 months.

Genotypic and phenotypic predictors of inflammation in patients with chronic kidney disease.

Background: In complex diseases such as chronic kidney disease (CKD), the risk of clinical complications is determined by interactions between phenotypic and genotypic factors. However, clinical epidemiological studies rarely attempt to analyse the combined effect of large numbers of phenotype and genotype features. We have recently shown that the relaxed linear separability (RLS) model of feature selection can address such complex issues.

Telomere Attrition and Elongation after Chronic Dialysis Initiation in Patients with End-Stage Renal Disease.

Aims: To analyze changes in telomere length (TL) after dialysis initiation.

Methods: In 59 Japanese incident dialysis patients, associations between TL in peripheral blood leukocytes, inflammatory biomarkers and nutritional status at baseline and changes in TL during 1 year of dialysis, were investigated.

Results: Whereas relative TL decreased by 8.

Increased circulating sclerostin levels in end-stage renal disease predict biopsy-verified vascular medial calcification and coronary artery calcification.

Sclerostin, an osteocyte-derived inhibitor of bone formation, is linked to mineral bone disorder. In order to validate its potential as a predictor of vascular calcification, we explored associations of circulating sclerostin with measures of calcification in 89 epigastric artery biopsies from patients with end-stage renal disease. Significantly higher sclerostin levels were found in the serum of patients with epigastric and coronary artery calcification (calcification score 100 or more).

How can genetics and epigenetics help the nephrologist improve the diagnosis and treatment of chronic kidney disease patients?

Discovery of novel improved tools for diagnosis, prevention and therapy of chronic kidney disease (CKD) is an important task for the nephrology community and it is likely that scientific breakthroughs, to a large extent, will be based on genomics. The rapid growth of the number of genome-wide association studies, major advances in DNA sequencing and omics profiling, and accelerating biomedical research efforts in this area have greatly expanded the knowledge base needed for applied genomics. However, translating and implementing genotype-phenotype data into gene-based medicine in CKD populations is still in an early phase and will require continuous research efforts with integrated approaches and intensified investigations that focus on the biological pathways, which causatively link a genetic variant with the disease phenotype.

Selection of genetic and phenotypic features associated with inflammatory status of patients on dialysis using relaxed linear separability method.

Identification of risk factors in patients with a particular disease can be analyzed in clinical data sets by using feature selection procedures of pattern recognition and data mining methods. The applicability of the relaxed linear separability (RLS) method of feature subset selection was checked for high-dimensional and mixed type (genetic and phenotypic) clinical data of patients with end-stage renal disease. The RLS method allowed for substantial reduction of the dimensionality through omitting redundant features while maintaining the linear separability of data sets of patients with high and low levels of an inflammatory biomarker.

Novel insights from genetic and epigenetic studies in understanding the complex uraemic phenotype.

Like in many other common complex disorders, studies of chronic kidney disease (CKD) can now make use of the increasing knowledge of the human genome, its variations and impact on disease susceptibility, initiation, progression and complications. Such studies are facilitated by novel readily available high through-put genotyping methods and sophisticated analytical approaches to scan the genome for DNA variations and epigenetic modifications. Here, we review some of the recent discoveries that have emerged from these studies and expanded our knowledge of genetic risk loci and epigenetic markers in CKD pathophysiology.

Global DNA hypermethylation is associated with high serum levels of persistent organic pollutants in an elderly population.

Dioxin exposure has experimentally been associated with changes in DNA methylation, an epigenetic change that is associated with disease. The present study aims to investigate if serum levels of dioxin and other persistent environmental pollutants are related to global DNA methylation in a human sample. In the population-based Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) study (all aged 70), global DNA methylation was measured by the Luminometric Methylation Assay in 524 subjects.

Elevated circulating levels and tissue expression of pentraxin 3 in uremia: a reflection of endothelial dysfunction.

Elevated systemic pentraxin 3 (PTX3) levels appear to be a powerful marker of inflammatory status and a superior outcome predictor in patients with chronic kidney disease (CKD). As previous data imply that PTX3 is involved in vascular pathology and that adipose tissue mass may influence circulating PTX3 levels, we aimed to study the importance of adipose tissue expression of PTX3 in the uremic milieu and its relation to endothelial dysfunction parameters. Plasma PTX3 and abdominal subcutaneous adipose tissue (SAT) PTX3 mRNA levels were quantified in 56 stage 5 CKD patients (median age 57 [range 25-75] years, 30 males) and 40 age and gender matched controls (median age 58 [range 20-79] years, 27 males).

Genetic studies in chronic kidney disease: interpretation and clinical applicability.

The tools of modern molecular biology are evolving rapidly, resulting in vastly more efficient approaches to illuminating human genetic variations and their effects on common multifactorial disorders such as chronic kidney disease (CKD). Indeed, candidate gene association studies and genome-wide association studies (GWASs) have generated novel genetic variants in previously unrecognized biological pathways, highlighting disease mechanisms with a potential role in CKD etiology, morbidity and mortality. Nephrologists now need to find ways to make use of these advancements and meet the increasingly stringent requirements for valid study design, data handling and interpretation of genetic studies.

Genetic studies in chronic kidney disease: basic concepts.

In spite of extensive research resulting in major advances in renal care including technological improvements of dialysis, the poor outcome of chronic kidney disease patients has only marginally been improved since the 1980s. It has thus become clear that new strategies are needed to move forward. There are now great expectations that increased knowledge about genetic characteristics combined with other biological markers will identify pathophysiological pathways involved in the initiation and progression of renal damage and that this in turn will help define tools for early disease intervention and personalized treatment strategies.

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.

Is fetuin-A a mortality risk factor in dialysis patients or a mere risk marker? A Mendelian randomization approach.

Background: Low levels of circulating fetuin-A are associated with increased mortality in dialysis patients. This study aimed to examine a potential causative role for fetuin-A on mortality by investigating whether a functional polymorphism in the alpha2-Heremans-Schmid glycoprotein (AHSG) gene associates with mortality, and by estimating the causative effect of fetuin-A levels on mortality using a Mendelian randomization design.

Methods: One thousand and forty-three incident dialysis patients were genotyped for the Thr256Ser polymorphism (rs4918) and followed up for 5 years; in 549 patients, serum fetuin-A levels were measured.

Expression of inflammatory and insulin signaling genes in adipose tissue in response to elective surgery.

Context: The mechanisms behind postoperative insulin resistance and impaired glucose utilization are not fully understood.

Objective: In this study, we aimed to specifically evaluate the transcription profile of genes in the insulin and adipokine signaling pathways in sc and omental adipose tissue after surgical injury.

Design: Relative expression of 21 target genes was analyzed in both sc and omental adipose tissue sampled at the beginning and at the end of operation.

Genetic loci influencing kidney function and chronic kidney disease.

Using genome-wide association, we identify common variants at 2p12-p13, 6q26, 17q23 and 19q13 associated with serum creatinine, a marker of kidney function (P = 10(-10) to 10(-15)). Of these, rs10206899 (near NAT8, 2p12-p13) and rs4805834 (near SLC7A9, 19q13) were also associated with chronic kidney disease (P = 5.0 x 10(-5) and P = 3.

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.

Influence of the CYP2D6 polymorphism and hemodialysis on codeine disposition in patients with end-stage renal disease.

Objective: We studied the influence of three factors on drug disposition: genetic polymorphism, impaired renal excretion of drug metabolites, and the possible elimination by hemodialysis (HD), using codeine as a model drug.

Methods: Based on the genotyping of three CYP2D6 polymorphisms in 228 HD patients, nine extensive metabolizers (EMs) and two poor metabolizers (PMs) were given a single oral dose of 50 mg codeine phosphate. Plasma concentrations of its metabolites codeine-6-glucuronide (C6G), morphine-3-glucuronide (M3G), and morphine-6-glucuronide (M6G) were determined after 2, 4, 6, 8 and 24 h (beginning of the HD session) and again after 4 h of HD (28 h).

Genetics/Genomics in chronic kidney disease--towards personalized medicine?

The progression rate of chronic kidney disease (CKD) to its terminal stage, end-stage renal disease (ESRD), and the development and severity of various complications, are at least indirectly influenced by genetic--and epigenetic--factors. For years, scientists have held out hope that the rapidly evolving field of genetics could transform medical diagnosis and treatment, moving beyond a trial-and-error approach towards "personalized medicine." Indeed, there are now signs that the role of genetics and the pursuit of "personalized medicine" in medical care will be a priority for governments during years to come.

CCR5 deletion protects against inflammation-associated mortality in dialysis patients.

The CC-chemokine receptor 5 (CCR5) is a receptor for various proinflammatory chemokines, and a deletion variant of the CCR5 gene (CCR5 Delta 32) leads to deficiency of the receptor. We hypothesized that CCR5 Delta 32 modulates inflammation-driven mortality in patients with ESRD. We studied the interaction between CCR5 genotype and levels of high-sensitivity C-reactive protein (hsCRP) in 603 incident dialysis patients from the multicenter, prospective NEtherlands COoperative Study on the Adequacy of Dialysis (NECOSAD) cohort.

Increased expression of inflammatory pathway genes in skeletal muscle during surgery.

Background & Aims: Postoperative insulin resistance, resulting in hyperglycemia, is strongly associated to morbidity and mortality in surgical patients but the underlying mechanisms are unclear. As increasing data suggests a link between inflammation and insulin resistance, we aimed to evaluate if the expression of inflammatory and insulin signaling genes is regulated in skeletal muscle during surgery.

Methods: Eight patients (4 females, 63 [46-69] years, body mass index 25.