Apolipoprotein J/Clusterin in Human Erythrocytes Is Involved in the Molecular Process of Defected Material Disposal during Vesiculation

BACKGROUND: We have showed that secretory Apolipoprotein J/Clusterin (sCLU) is down-regulated in senescent, stressed or diseased red blood cells (RBCs). It was hypothesized that sCLU loss relates to RBCs vesiculation, a mechanism that removes erythrocyte membrane patches containing defective or potentially harmful components. METHODOLOGY/PRINCIPAL FINDINGS: To investigate this issue we employed a combination of biochemical and microscopical approaches in freshly prepared RBCs or RBCs stored under standard blood bank conditions, an in vitro model system of cellular aging. We found that sCLU is effectively exocytosed in vivo during membrane vesiculation of freshly prepared RBCs. In support, the RBCs' sCLU content was progressively reduced during RBCs ex vivo maturation and senescence under cold storage due to its selective exocytosis in membrane vesicles. A range of typical vesicular components, also involved in RBCs senescence, like Band 3, CD59, hemoglobin and carbonylated membrane proteins were found to physically interact with sCLU. CONCLUSIONS/SIGNIFICANCE: The maturation of RBCs is associated with a progressive loss of sCLU. We propose that sCLU is functionally involved in the disposal of oxidized/defected material through RBCs vesiculation. This process most probably takes place through sCLU interaction with RBCs membrane proteins that are implicit vesicular components. Therefore, sCLU represents a pro-survival factor acting for the postponement of the untimely clearance of RBCs

In Sickness and in Health: Erythrocyte Responses to Stress and Aging

Mature red blood cells (RBC) are the most abundant host cell in our body [...

Blood Cell-Derived Microvesicles in Hematological Diseases and beyond

Microvesicles or ectosomes represent a major type of extracellular vesicles that are formed by outward budding of the plasma membrane. Typically, they are bigger than exosomes but smaller than apoptotic vesicles, although they may overlap with both in size and content. Their release by cells is a means to dispose redundant, damaged, or dangerous material; to repair membrane lesions; and, primarily, to mediate intercellular communication. By participating in these vital activities, microvesicles may impact a wide array of cell processes and, consequently, changes in their concentration or components have been associated with several pathologies. Of note, microvesicles released by leukocytes, red blood cells, and platelets, which constitute the vast majority of plasma microvesicles, change under a plethora of diseases affecting not only the hematological, but also the nervous, cardiovascular, and urinary systems, among others. In fact, there is evidence that microvesicles released by blood cells are significant contributors towards pathophysiological states, having inflammatory and/or coagulation and/or immunomodulatory arms, by either promoting or inhibiting the relative disease phenotypes. Consequently, even though microvesicles are typically considered to have adverse links with disease prognosis, progression, or outcomes, not infrequently, they exert protective roles in the affected cells. Based on these functional relations, microvesicles might represent promising disease biomarkers with diagnostic, monitoring, and therapeutic applications, equally to the more thoroughly studied exosomes. In the current review, we provide a summary of the features of microvesicles released by blood cells and their potential implication in hematological and non-hematological diseases

Redox Status, Procoagulant Activity, and Metabolome of Fresh Frozen Plasma in Glucose 6-Phosphate Dehydrogenase Deficiency

ObjectiveTransfusion of fresh frozen plasma (FFP) helps in maintaining the coagulation parameters in patients with acquired multiple coagulation factor deficiencies and severe bleeding. However, along with coagulation factors and procoagulant extracellular vesicles (EVs), numerous bioactive and probably donor-related factors (metabolites, oxidized components, etc.) are also carried to the recipient. The X-linked glucose 6-phosphate dehydrogenase deficiency (G6PD−), the most common human enzyme genetic defect, mainly affects males. By undermining the redox metabolism, the G6PD− cells are susceptible to the deleterious effects of oxidants. Considering the preferential transfusion of FFP from male donors, this study aimed at the assessment of FFP units derived from G6PD− males compared with control, to show whether they are comparable at physiological, metabolic and redox homeostasis levels.MethodsThe quality of n = 12 G6PD− and control FFP units was tested after 12 months of storage, by using hemolysis, redox, and procoagulant activity-targeted biochemical assays, flow cytometry for EV enumeration and phenotyping, untargeted metabolomics, in addition to statistical and bioinformatics tools.ResultsHigher procoagulant activity, phosphatidylserine positive EVs, RBC-vesiculation, and antioxidant capacity but lower oxidative modifications in lipids and proteins were detected in G6PD− FFP compared with controls. The FFP EVs varied in number, cell origin, and lipid/protein composition. Pathway analysis highlighted the riboflavin, purine, and glycerolipid/glycerophospholipid metabolisms as the most altered pathways with high impact in G6PD−. Multivariate and univariate analysis of FFP metabolomes showed excess of diacylglycerols, glycerophosphoinositol, aconitate, and ornithine but a deficiency in riboflavin, flavin mononucleotide, adenine, and arginine, among others, levels in G6PD− FFPs compared with control.ConclusionOur results point toward a different redox, lipid metabolism, and EV profile in the G6PD− FFP units. Certain FFP-needed patients may be at greatest benefit of receiving FFP intrinsically endowed by both procoagulant and antioxidant activities. However, the clinical outcome of G6PD− FFP transfusion would likely be affected by various other factors, including the signaling potential of the differentially expressed metabolites and EVs, the degree of G6PD−, the redox status in the recipient, the amount of FFP units transfused, and probably, the storage interval of the FFP, which deserve further investigation by future studies

Short-term effects of hemodiafiltration versus conventional hemodialysis on erythrocyte performance

Hemodiafiltration (HDF) is a renal replacement therapy which is based on the principles of diffusion and convection for the elimination of uremic toxins. A significant and increasing number of end stage renal disease (ESRD) patients are treated with HDF, even in the absence of definite and conclusive survival and anemia treatment data. However, its effects on red blood cell (RBC) physiological features have not been examined in depth. In this study, ESRD patients under regular HDF or conventional hemodialysis (cHD) treatment were examined for RBC-related parameters, including anemia, hemolysis, cell shape, redox status, removal signaling, membrane protein composition and microvesiculation, in repeated paired measurements accomplished before and right after each dialysis session. HDF-group was characterized by better redox potential and suppressed exovesiculation of blood cells compared to the cHD-group pre-dialysis. However, HDF was associated with a temporary but acute, oxidative stress-driven increase in hemolysis, RBC removal signaling and stomatocytosis, probably associated with the effective clearance of dialyzable natural antioxidant components, including uric acid, from the uremic plasma. The nature of these adverse short-term effects of HDF on post-dialysis plasma and RBCs strongly suggests the use of a parallel antioxidant therapy during the HDF session.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Progressive decrease in the erythrocytes sCLU levels during <i>ex vivo</i> cellular senescence.

<p>Representative sCLU immunoblot (A₁) and densitometric analysis (A₂) of membrane (A₁, upper panels) and cytosol (A₁, lower panels) preparations derived from leukoreduced RBCs units (N = 4) stored for the indicated duration in SAGM solution. (B) Comparative densitometric analysis of immunoblots (not shown) of sCLU relative membrane levels in RBCs stored either in SAGM (N = 4; max 42 days of storage) or autologous plasma (Au-Pl) (N = 3; max 35 days of storage). Probing with anti-4.1R and anti-peroxiredoxin-2 (Prx2) was used as a protein loading reference. Shown densitometric data (mean values of at least two independent experiments) indicate relative proportion against a loading reference followed by normalization against the samples stored for a short period (e.g. 4 days); error bars indicate ± standard deviation. Asterisks and dots indicate difference of each day of storage vs. day 4 and SAGM vs. Au-Pl respectively, at significance level of p<0.05.</p