Anemia and the Heart in Chronic Kidney Disease

Integrated metabolomics and proteomics reveal biomarkers associated with hemodialysis in end-stage kidney disease

Background: We hypothesize that the poor survival outcomes of end-stage kidney disease (ESKD) patients undergoing hemodialysis are associated with a low filtering efficiency and selectivity. The current gold standard criteria using single or several markers show an inability to predict or disclose the treatment effect and disease progression accurately. Methods: We performed an integrated mass spectrometry-based metabolomic and proteomic workflow capable of detecting and quantifying circulating small molecules and proteins in the serum of ESKD patients. Markers linked to cardiovascular disease (CVD) were validated on human induced pluripotent stem cell (iPSC)-derived cardiomyocytes. Results: We identified dozens of elevated molecules in the serum of patients compared with healthy controls. Surprisingly, many metabolites, including lipids, remained at an elevated blood concentration despite dialysis. These molecules and their associated physical interaction networks are correlated with clinical complications in chronic kidney disease. This study confirmed two uremic toxins associated with CVD, a major risk for patients with ESKD. Conclusion: The retained molecules and metabolite-protein interaction network address a knowledge gap of candidate uremic toxins associated with clinical complications in patients undergoing dialysis, providing mechanistic insights and potential drug discovery strategies for ESKD.

Effect of Chronic Kidney Disease or Anemia or Both on Cardiovascular Mortality in a 25-Year Follow-Up Study of Japanese General Population (From NIPPON DATA90)

The relation between chronic kidney disease (CKD) and cardiovascular disease (CVD) in the general population is well elucidated. In patients with CKD, anemia is associated with adverse outcomes. However, the effects of CKD and anemia on CVD in the general population remains poorly explored, especially in Asian populations. This study aimed to investigate the effect of CKD and/or anemia on CVD mortality in a long-term cohort study involving Japanese community dwellers. We assessed 7,339 participants (aged ≥30 years) with no CVD history. These participants were divided into 4 categories according to their CKD (estimated glomerular filtration rate <60 or urine protein >1+ by dipstick qualitative test) and/or anemia (hemoglobin: <13 g/100 ml [men], <12 g/100 ml [women]) statuses. For each category, we calculated the hazard ratios (HRs) of CVD mortality by using the Cox proportional hazards model after adjusting for age, body mass index, hypertension, diabetes, dyslipidemia, smoking, and alcohol drinking. Within 25 years of follow-up, 637 participants died because of CVD. The HRs of CVD in patients with CKD only, anemia only, and both were 1.27, 1.59, and 2.60 (95% confidence intervals [CI] 1.06 to 1.53, 1.34 to 1.90, and 1.80 to 3.76) in men and 1.42, 1.08, and 2.00 (95% CI 1.19 to 1.69, 0.99 to 1.18, and 1.54 to 2.60) in women, respectively. In conclusion, CKD with anemia is associated with an increased risk for CVD mortality in a general population in Japan.

Effect of diabetes mellitus on markers of left ventricular dysfunction in chronic kidney disease

OBJECTIVES

To identify markers of left ventricular dysfunction in chronic kidney disease (CKD) and the effects of diabetes mellitus on them.

METHODS

This was a cross sectional study of 200 consecutive chronic kidney disease patients (stage III-V). Echocardiographic assessment of left ventricular function including left ventricular ejection fraction (LVEF), left ventricular mass index (LVMI), left atrial volume, grade of diastolic dysfunction, E/E', left and right ventricular myocardial performance indices (LVMPI, RVMPI) were compared between diabetic and non-diabetic CKD.

RESULTS

LVMI significantly increased with increasing stage of CKD (p < 0.001) in both diabetics (158.82 ± 48.76 gm/m2 in stage III to 201.06 ± 63.62 gm/m2 in stage V) and non-diabetics (133.14 ± 43.06 gm/m2 stage III to 196.24 ± 58.75 gm/m2 in stage V). This was significantly higher among diabetics of similar CKD stage compared to non-diabetics (p = 0.001). The LVEF worsened with increasing stage of CKD (p = 0.002) and was significantly reduced in diabetic patients (LVEF 61.96 ± 8.48 % in stage III CKD to 51.62 ± 13.45 % in stage V CKD) (p < 0.001). Diastolic dysfunction (Grades ≥2) and LA volume increased significantly with stage of CKD (p < 0.001) and was higher among diabetics (p = 0.048). Pulmonary artery systolic pressure (PASP) increased with increasing stage of CKD (p < 0.001), and was higher among diabetics (p = 0.035). E/E' worsened significantly with increasing stage of CKD and was also significantly higher in diabetics (p < 0.001). LVMPI (p < 0.001) and RVMPI (p < 0.001) were significantly reduced with worsening stage of CKD and in diabetics.

CONCLUSION

Advancing CKD stage was linearly associated with progressive left ventricular dysfunction which was significantly greater in diabetics.

Cardiovascular risk using WHO-ISH chart among Diabetes and Hypertensive patients in a remote rural area of South India

INTRODUCTION

Cardiovascular diseases (CVDs) are major problems in India and many other developing and developed countries. As India is committed to provide universal health care for the population, there is a need to find out the prevalence and determinants of CVD risk among high-risk individuals (Diabetes and Hypertensive patients) in the remote rural area of India to deliver appropriate services, as they are considered as neglected population.

METHODS

We screened high-risk individuals (Hypertension and Diabetes patients) for CVD risk using WHO/ISH chart, in a remote rural area of south India, covering ten villages surrounding the Rural Health Training Centre (RHTC), in August-September 2017. After line-listing the participants from the electronic database of RHTC, screening with questionnaire and biochemical tests was done at village level as the first step. Thereafter, the participants were invited to the hospital on a particular day where electrocardiography (ECG) and echocardiography (ECHO) were done with special consultation.

RESULTS

Among the total of 303 individuals screened at the village level, 64 [21%(CI 17-25)] had a higher risk for CVD. 235 people attended the special consultation; among them, 212 underwent ECG and 88 underwent ECHO. Among those screened with ECHO, 18 had some cardiac pathologies. The relationship between CVD risk and other factors is shown in. After final adjustment, illiteracy [adjusted prevalence ratio (aPR) 1.8 (0.1-3.1)], anemia [aPR 1.8 (1-3.6)], and chronic renal diseases [aPR 1.8 (1.0-3.4)] were found to be associated with high risk for CVD among hypertension and diabetes groups.

CONCLUSION

Cardiovascular disease risk assessment using WHO/ISH chart showed an association with poor education, anemia, and chronic kidney disease.

Patient-Centred Outcomes in Anaemia and Renal Disease: A Systematic Review

Background

Anaemia is a nearly universal complication of chronic kidney disease (CKD). Erythropoiesis-stimulating agents (ESAs) have been demonstrated to improve clinical outcomes and quality of life (QOL) in renal patients with anaemia. Patient-reported outcome measures (PROMs) are increasingly being used to evaluate the patient-centred impact of medical therapy. Here, we describe a systematic review of studies that evaluated patient-centred outcomes (PCOs) in renal patients undergoing anaemia treatment.

Methods

We conducted a search of Medline (Ovid), EMBASE (Ovid), PsychINFO, and CINAHL databases for studies published until March 2018 that investigated an intervention to treat anaemia in renal patients and used at least one PROM. We also performed a quality assessment for all included studies. Statistical analyses characterized each study, PROMs used, the quality of PCO reporting, and the association between haematological outcomes and PCOs.

Results

Of the 3,533 studies identified in the database search, 21 met all eligibility criteria. Fourteen (67%) of the studies were randomized-controlled trials. Most studies (81%) investigated CKD patients, 14% investigated post-renal transplant patients and 5% assessed patients with heart disease on haemodialysis. The most common anaemia intervention, used in 95% of studies, was ESAs. Forty-three percent of studies utilized one PROM, most commonly the SF-36, a measure of QOL not specifically created for use in nephrology patients. About a third of studies selectively reported PROM subscales, rather than reporting all subscales. Notable biases among included studies included lack of blinding, selective outcome reporting, and lack of power estimates for PCOs. We did not find a statistically significant association between improvements in haemoglobin and QOL.

Conclusions

Future studies employing anaemia and nephrology-specific PROMs and conducted with greater rigour, standardization in the research methods, and reporting of PCOs in renal populations will improve understanding of PCOs in this patient group and hopefully improve patient outcomes and experiences.

Whole-body iron transport and metabolism: Mechanistic, multi-scale model to improve treatment of anemia in chronic kidney disease

Iron plays vital roles in the human body including enzymatic processes, oxygen-transport via hemoglobin and immune response. Iron metabolism is characterized by ~95% recycling and minor replenishment through diet. Anemia of chronic kidney disease (CKD) is characterized by a lack of synthesis of erythropoietin leading to reduced red blood cell (RBC) formation and aberrant iron recycling. Treatment of CKD anemia aims to normalize RBC count and serum hemoglobin. Clinically, the various fluxes of iron transport and accumulation are not measured so that changes during disease (e.g., CKD) and treatment are unknown. Unwanted iron accumulation in patients is known to lead to adverse effects. Current whole-body models lack the mechanistic details of iron transport related to RBC maturation, transferrin (Tf and TfR) dynamics and assume passive iron efflux from macrophages. Hence, they are not predictive of whole-body iron dynamics and cannot be used to design individualized patient treatment. For prediction, we developed a mechanistic, multi-scale computational model of whole-body iron metabolism incorporating four compartments containing major pools of iron and RBC generation process. The model accounts for multiple forms of iron in vivo, mechanisms involved in iron uptake and release and their regulation. Furthermore, the model is interfaced with drug pharmacokinetics to allow simulation of treatment dynamics. We calibrated our model with experimental and clinical data from peer-reviewed literature to reliably simulate CKD anemia and the effects of current treatment involving combination of epoietin-alpha and iron dextran. This in silico whole-body model of iron metabolism predicts that a year of treatment can potentially lead to 90% downregulation of ferroportin (FPN) levels, 15-fold increase in iron stores with only a 20% increase in iron flux from the reticulo-endothelial system (RES). Model simulations quantified unmeasured iron fluxes, previously unknown effects of treatment on FPN-level and iron stores in the RES. This mechanistic whole-body model can be the basis for future studies that incorporate iron metabolism together with related clinical experiments. Such an approach could pave the way for development of effective personalized treatment of CKD anemia.

Post-renal transplantation anemia at 12 months: prevalence, risk factors, and impact on clinical outcomes

PURPOSE

To investigate any association between post-transplantation anemia (PTA) and clinical outcomes following living donor kidney transplantation.

METHODS

We retrospectively evaluated 887 patients who received living donor kidney transplantations at our medical center between January 2006 and December 2012 to evaluate whether PTA, defined as serum hemoglobin (Hb) levels of <130 g/l in men and <120 g/l in women, at 12 months is associated with post-transplant outcomes, including graft function, death-censored graft survival, or patient survival.

RESULTS

The prevalence of PTA at 1, 3, 6, and 12 months was 84.3, 39.5, 26.2, and 21.6 %, respectively. Donor age [hazard ratio (HR), 1.03; 95 % confidence interval (CI) 1.01-1.05] and acute rejection (HR 2.13; 95 % CI 1.28-3.54) were found to be independent risk factors for PTA at 12 months. Recipient age (HR 0.98; 95 % CI 0.95-1.00), pre-transplantation Hb levels (HR 0.99; 95 % CI 0.98-1.00), and estimated glomerular filtration rates (eGFRs) at 12 months (HR 0.96; 95 % CI 0.94-0.97) were found to confer slight protection against PTA at 12 months. PTA at 12 months was associated with increased graft loss (HR 1.046; 95 % CI 1.045-1.046). For each increase in anemia degree, there was a 2.77-fold greater risk of graft loss (HR 2.77; 95 % CI 1.50-5.13). When stratified according to eGFR, PTA was found to be a predictor of graft loss in patients with an eGFR of <60 ml/min/1.73 m(2) (HR 4.57; 95 % CI 1.98-10.56) but not in patients with an eGFR of >60 ml/min/1.73 m(2) (HR 1.89; 95 % CI 0.13-27.78). PTA was not found to be a predictor of patient survival.

CONCLUSIONS

Anemia is common after kidney transplantation, and its prevalence declines with time after transplantation. Presence of anemia at 12 months post-transplant was an independent predictor of graft loss, with higher risk of graft loss in patients with anemia and poorer kidney functions.

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

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

Pathophysiology of anemia and erythrocytosis

An increasing understanding of the process of erythropoiesis raises some interesting questions about the pathophysiology, diagnosis and treatment of anemia and erythrocytosis. The mechanisms underlying the development of many of the erythrocytoses, previously characterised as idiopathic, have been elucidated leading to an increased understanding of oxygen homeostasis. Characterisation of anemia and erythrocytosis in relation to serum erythropoietin levels can be a useful addition to clinical diagnostic criteria and provide a rationale for treatment with erythropoiesis stimulating agents (ESAs). Recombinant human erythropoietin as well as other ESAs are now widely used to treat anemias associated with a range of conditions, including chronic kidney disease, chronic inflammatory disorders and cancer. There is also heightened awareness of the potential abuse of ESAs to boost athletic performance in competitive sport. The discovery of erythropoietin receptors outside of the erythropoietic compartment may herald future applications for ESAs in the management of neurological and cardiac diseases. The current controversy concerning optimal hemoglobin levels in chronic kidney disease patients treated with ESAs and the potential negative clinical outcomes of ESA treatment in cancer reinforces the need for cautious evaluation of the pleiotropic effects of ESAs in non-erythroid tissues.