A role for the membrane proteome in human chronic kidney disease erythrocytes.
ABSTRACT The molecular basis of the reduced half-life of chronic kidney disease (CKD) erythrocytes is unclear. The erythrocyte membrane plays a key role in the erythrocyte mechanical properties and survival. The aim of the present work is to uncover erythrocyte membrane proteins whose expression could be altered in CKD. The erythrocyte membrane subproteome was analyzed by a non-biased approach where the whole set of proteins was simultaneously investigated by 2D fluorescence difference gel electrophoresis without preselection of potential targets. Proteins significantly altered in CKD were identified by mass spectrometry (MS) and results validation was performed by Western blot and confocal microscopy. Nine differentially expressed spots among healthy individuals, non-dialyzed CKD and erythropoietin/dialysis-treated CKD patients were identified by MS/MS corresponding to 5 proteins (beta-adducin, HSP71/72, tropomodulin-1, ezrin, and radixin). Ezrin and radixin were higher in dialyzed CKD patients than in the other 2 groups. Beta-adducin was increased in CKD patients (dialyzed or not). Three spots were normalized in patients on the dialysis/erythropoietin combination compared with non-dialyzed CKD. Among these, a spot corresponding to tropomodulin 1, was found to be of higher abundance in non-dialyzed CKD patients compared with controls or dialyzed CKD. In conclusion, this study identifies changes in erythrocyte membrane proteins in CKD, which may be relevant for the pathogenesis of red cell abnormalities in uremia.
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ABSTRACT: Gliding of red blood cells (RBC) through blood vessels is mediated by the negatively charged glycocalyx located on the surfaces of both RBC and endothelial cells (EC). In various vasculopathies, EC gradually lose this protective surface layer. As a consequence, RBC come into close physical contact with the vascular endothelium. It is hypothesized that the RBC glycocalyx could be adversely affected by a poor EC glycocalyx. This hypothesis was tested by evaluating the RBC and EC surface layers with atomic force microscopy techniques. In the first series of experiments, EC monolayers grown in culture were exposed to rhythmic drag forces exerted from a blood overlay (drag force treatment), and thereafter, the EC surface was investigated in terms of thickness and adhesiveness. In the second series, the glycocalyx of the EC monolayers was disturbed by enzymatic cleavage of negatively charged heparan sulfates before drag force treatment, and thereafter, the RBC surface was evaluated. In the third series, the RBC glycocalyx of the blood overlay was enzymatically disturbed before drag force treatment, and thereafter, the EC surface was evaluated. A strong positive correlation between the RBC and EC surface properties was found (r (2) = 0.95). An enzymatically affected EC glycocalyx lead to the shedding of the RBC glycocalyx and vice versa. It is concluded that there is physical interaction between the blood and endothelium. Apparently, the RBC glycocalyx reflects properties of the EC glycocalyx. This observation could have a significant impact on diagnosis and treatment of cardiovascular diseases.Pflügers Archiv - European Journal of Physiology 05/2013; · 4.87 Impact Factor
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ABSTRACT: In humans, when plasma sodium concentration rises slightly beyond 140 mM, vascular endothelium sharply stiffens and nitric oxide release declines. In search of a vascular sodium sensor, the endothelial glycocalyx was identified as being a negatively charged biopolymer capable of selectively buffering sodium ions. Sodium excess damages the glycocalyx and renders vascular endothelium increasingly permeable for sodium. In the long term, sodium accumulates in the interstitium and gradually damages the organism. It was discovered that circulating red blood cells (RBC) 'report' surface properties of the vascular endothelium. To some extent, the RBC glycocalyx mirrors the endothelial glycocalyx. A poor (charge-deprived) endothelial glycocalyx causes a poor RBC glycocalyx and vice versa. This observation led to the assumption that the current state of an individual's vascular endothelium in terms of electrical surface charges and sodium-buffering capabilities could be read simply from a blood sample. Recently, a so-called salt blood test was introduced that quantifies the RBC sodium buffer capacity and thus characterizes the endothelial function. The arguments are outlined in this article spanning a bridge from cellular nano-mechanics to clinical application.Nephrology Dialysis Transplantation 12/2013; · 3.37 Impact Factor
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ABSTRACT: Chronic kidney disease is a risk factor for cardiovascular mortality. This study uncovers pieces of hematological and erythrocyte protein variability observed in end stage renal disease (ESRD) in relation to disease progression/duration and mortality. Using a variety of experimental approaches, erythropoietin/dialysis-treated patients were compared to healthy individuals and had been followed for 36months. During that period, half of the patients died from cardiovascular diseases. The high levels of uremic toxins in those patients were associated with damaged erythrocytes, bad tolerance and poor response to hemodialysis therapy. The postmortem study revealed significant variation in alkaline phosphatase, duration of dialysis, erythrocyte transformation and intracellular hemoglobin concentration compared to the survived patients. The erythrocyte proteins showed substantial remodeling characteristic of pathologic regulation of cell hydration and susceptibility to the dialysis-induced oxidation defects. According to the following-up study, duration of hemodialysis was associated with a trend towards increased intracellular hemoglobin concentration, membrane expression of glucose transporter-1 and stomatin as well as lower levels of circulating stomatocytes. The uremic indexes variation in long survived patients is accurately reflected in plasma and erythrocyte oxidative stress modifications. The ESRD patients exhibit impressive compensatory responses to the chronic challenges of the uremic milieu. This study demonstrates novel blood modifications probably associated with the duration of erythropoietin/hemodialysis treatment, disease progression and cardiovascular mortality in end stage renal disease. The observed variability adds new pieces to the erythrocytes pathophysiology puzzle in end stage renal disease and suggests novel hematologic and proteomic factors for consideration in future large scale studies on cardiovascular morbidity and mortality candidate biomarkers in uremic patients.Journal of proteomics 02/2014; · 5.07 Impact Factor