Epoetin beta pegol for treatment of anemia ameliorates deterioration of erythrocyte quality associated with chronic kidney disease

Background

Epoetin beta pegol (continuous erythropoietin receptor activator; C.E.R.A.) is currently widely used for the treatment of anemia associated with chronic kidney disease (CKD). Therapeutic control of anemia is assessed by monitoring haemoglobin (Hb) levels. However, certain qualitative aspects of erythrocytes are also impaired in CKD, including loss of deformability and shortened life-span. Therefore, monitoring Hb alone could potentially fail to reveal pathological changes in erythrocytes. Focusing on erythrocyte quality in CKD may lead to more effective anemia therapy with C.E.R.A.

Methods

A CKD rat model was induced by uninephrectomy followed by anti-Thy1.1 antibody injection. From 5 weeks after the operation, C.E.R.A. (0.6 μg/kg) or vehicle was administered every 2 weeks. Erythrocyte deformability was quantified with ektacytometry and erythrocyte turnover was estimated by biotin labeling. Intracellular calcium level was assessed by Fluo-3/AM.

Results

Erythrocyte deformability progressively declined in CKD rats. Furthermore, erythrocyte turnover in the circulation drastically accelerated in CKD rats. With administration of C.E.R.A. at a dose sufficient to adequately control Hb, deterioration of erythrocyte deformability and turnover in CKD rats were significantly improved. Intracellular calcium, which plays a pivotal role in the mediation of erythrocyte quality, was significantly increased in CKD and was normalized by C.E.R.A. treatment.

Conclusion

C.E.R.A. treatment exerted a favorable effect not only on anemia but also on the improvement of erythrocyte quality. C.E.R.A. administered for the treatment of CKD-associated anemia may confer therapeutic benefits on erythrocytes.

Hypervolemia, hypoalbuminemia and mitral calcification as markers of cardiovascular risk in peritoneal dialysis patients

INTRODUCTION

Mortality in patients with end-stage renal disease is higher than in the general population. This is linked to traditional and non-traditional cardiovascular (CV) risk factors, as well as with risk factors associated with end-stage renal disease itself. The aim of this study is to identify CV risk markers in patients beginning peritoneal dialysis (PD) and their association with CV events and CV mortality.

METHODS

This was a retrospective cohort study of 112 incident PD patients, in which demographic, clinical and laboratory parameters, valvular calcifications, types of PD solutions, hospitalizations, CV events and death were analyzed. Occurrence of CV events or death due to a CV event after PD initiation was defined as the primary endpoint. The use of icodextrin solution was taken as a marker of hypervolemia.

RESULTS

Mean age was 53.7±16.1 years. Patients were treated with PD for 29.3±17.4 months. Eighteen patients (16.1%) had valvular calcifications at baseline, 15 patients (13.4%) had major CV events and 11 patients (9.8%) died from CV-related causes. Cox proportional hazards analysis of CV events or CV-related mortality revealed that mitral calcification, use of icodextrin solution and low albumin were independent predictors of CV events or mortality.

CONCLUSIONS

Traditional CV risk factors appear to have little impact on CV complications in PD patients. Nevertheless, hypervolemia, hypoalbuminemia and mitral calcifications were independent predictors of CV events or mortality in this group of patients.

Erythropoietin activates nitric oxide synthase in murine erythrocytes

Erythropoietin (Epo) is the main regulator of erythrocyte production and a potent cytoprotective factor. It was suggested that some of Epo cytoprotective properties are due to its regulation of nitric oxide (NO) production. Recently, functionally active endothelial type NO synthase (eNOS) was discovered in mature murine and human red blood cells (RBC-eNOS). The goal of the present study was to characterize the effect of physiological and therapeutic doses of Epo on RBC-eNOS function. We found that recombinant human Epo (rHuEpo) binds specifically to mouse erythrocytes. Epo binding sites are not equally distributed through the RBC population but prevail in reticulocytes and young erythrocytes with about 105 receptors/cell, compared with adult and old erythrocytes containing 1-4 receptors/cell. The treatment of mouse erythrocytes with rHuEpo resulted in a time- and dose-dependent upregulation of NO production mediated via activation of the phosphatidylinositol-3-kinase /Akt pathway and RBC-eNOS phosphorylation at Ser-1177. Finally, when erythrocytes were incubated in L-arginine-free medium, rHuEpo treatment resulted in upregulation of superoxide radical production with concomitant shifting of the cellular redox state toward more oxidized state. Epo-induced changes in erythrocyte redox potential were absent in erythrocytes from eNOS-deficient mice.