Expression of CD55 on Red Blood Cells of β-Thalassemia Patients

Identification of coagulation diagnostic biomarkers related to the severity of spinal cord injury

BACKGROUND

Blood always shows coagulation changes after spinal cord injury (SCI), and identifying these blood changes may be helpful for diagnosis and treatment of SCI. Nevertheless, studies to date on blood coagulation changes after SCI in humans are not comprehensive. Therefore, this study aims to identify blood coagulation diagnostic biomarkers and immune changes related to SCI and its severity levels.

METHODS

Human blood sequencing datasets were obtained from public databases. Differentially expressed coagulation-related genes were analyzed (DECRGs). Enrichment analysis and assessment of immune changes were conducted. Weighted gene co-expression network analysis, least absolute shrinkage and selection operator logistic regression were used to identify biomarkers. Validation for these biomarkers was performed. The correlation between biomarkers and immune cells was evaluated. Transcription factors, miRNA, lncRNA, and drugs that can regulate biomarkers were analyzed.

RESULTS

DECRGs associated with SCI and its different grades were identified, showing enrichment in altered coagulation and immune-related signaling pathways. ADAM9, CD55, and STAT4 were identified as coagulation diagnostic biomarkers for SCI. IRF4 and PABPC4 were identified as coagulation diagnostic biomarkers for American Spinal Injury Association Impairment Scale (AIS) A grade of SCI. GP9 was designated as a diagnostic biomarker for AIS D grade of SCI. Immune changes in blood of SCI and its different grades were observed. Correlation between diagnostic biomarkers and immune cells were identified. Transcription factors, miRNA, lncRNA, and drugs that can regulate diagnostic biomarker expression were discovered.

CONCLUSION

Therefore, detecting the expression of these putative diagnostic biomarkers and related immune changes may be helpful for predicting the severity of SCI. Uncovering potential regulatory mechanisms for biomarkers may be beneficial for further research.

What is the role of complement in bystander hemolysis? Old concept, new insights

INTRODUCTION

Bystander hemolysis occurs when antigen-negative red blood cells (RBCs) are lysed by the complement system. Many clinical entities including passenger lymphocyte syndrome, hyperhemolysis following blood transfusion, and paroxysmal nocturnal hemoglobinuria are complicated by bystander hemolysis.

AREAS COVERED

The review provides data about the role of the complement system in the pathogenesis of bystander hemolysis. Moreover, future perspectives on the understanding and management of this syndrome are described.

EXPERT OPINION

Complement system can be activated via classical, alternative, and lectin pathways. Classical pathway activation is mediated by antigen-antibody (autoantibodies and alloantibodies against autologous RBCs, infectious agents) complexes. Alternative pathway initiation is triggered by heme, RBC microvesicles, and endothelial injury that is a result of intravascular hemolysis. Thus, C5b is formed, binds with C6-C9 compomers, and MAC (C5b-9) is formulated in bystander RBCs membranes, leading to cell lysis. Intravascular hemolysis, results in activation of the alternative pathway, establishing a vicious cycle between complement activation and bystander hemolysis. C5 inhibitors have been used effectively in patients with hyperhemolysis syndrome and other entities characterized by bystander hemolysis.

Fluorinated Silane-Modified Filtroporation Devices Enable Gene Knockout in Human Hematopoietic Stem and Progenitor Cells

Intracellular delivery technologies that are cost-effective, non-cytotoxic, efficient, and cargo-agnostic are needed to enable the manufacturing of cell-based therapies as well as gene manipulation for research applications. Current technologies capable of delivering large cargoes, such as plasmids and CRISPR-Cas9 ribonucleoproteins (RNPs), are plagued with high costs and/or cytotoxicity and often require substantial specialized equipment and reagents, which may not be available in resource-limited settings. Here, we report an intracellular delivery technology that can be assembled from materials available in most research laboratories, thus democratizing access to intracellular delivery for researchers and clinicians in low-resource areas of the world. These filtroporation devices permeabilize cells by pulling them through the pores of a cell culture insert by the application of vacuum available in biosafety cabinets. In a format that costs less than $10 in materials per experiment, we demonstrate the delivery of fluorescently labeled dextran, expression plasmids, and RNPs for gene knockout to Jurkat cells and human CD34+ hematopoietic stem and progenitor cell populations with delivery efficiencies of up to 40% for RNP knockout and viabilities of >80%. We show that functionalizing the surfaces of the filters with fluorinated silane moieties further enhances the delivery efficiency. These devices are capable of processing 500,000 to 4 million cells per experiment, and when combined with a 3D-printed vacuum application chamber, this throughput can be straightforwardly increased 6-12-fold in parallel experiments.

Thrombotic risk in paroxysmal nocturnal hemoglobinuria-like (PNH-like) phenotype

The complement system is an essential component of the innate immune defence that, if overly activated, may damage organs and tissues. For this reason, there is a fine complement regulatory system. The complement modulation system includes two proteins with important regulatory activity, CD55 or decay accelerating factor (DAF) and CD59 or membrane inhibitor of reactive lysis (MIRL).The paroxysmal nocturnal hemoglobinuria (PNH) is a clonal and non-neoplastic disease characterized by intravascular haemolysis, occurrence of thrombosis and bone marrow failure.In clinical practice, in opposition to PNH, a variety of pathological conditions have been observed with an acquired and non-genetic deficiency of the regulatory proteins CD55 and CD59. This abnormal, non-clonal, reduced expression of complement regulatory proteins configures what we may define as PNH-like phenotype.Similarly to PNH, even in the PNH-like phenotype diseases there has been a greater exposure to the mediated complement cellular lysis and, a likely increased risk of thromboembolic events.Therefore, the knowledge of the potential roles of the complement system becomes necessary for a deeper understanding of several pathological conditions and for an improved clinical management of the patients.

Selected CD molecules and the phagocytosis of microvesicles released from erythrocytes ex vivo

BACKGROUND AND OBJECTIVES

The accumulation of microvesicles in erythrocyte concentrates during storage or irradiation may be responsible for clinical symptoms such as inflammation, coagulation and immunization. Our aim was to determine whether any of the cluster of differentiation (CD) molecules responsible for important functions are present on microvesicles, and if their expression level is dependent on the storage period of erythrocyte concentrates.

MATERIAL AND METHODS

Erythrocyte microvesicles were isolated from 'fresh' (2^nd day) and 'old' (42^nd day) stored erythrocyte concentrates. Qualitative cytometric analysis of 0·5 µm, erythrocyte-derived, PS-exposing vesicles was performed using the annexin V-FITC, anti-CD235a-PE antibody and calibrated beads. The microvesicles were also visualized under a confocal microscope. The expression of the molecules CD235a, CD44, CD47, CD55, CD59 and of phosphatidylserine (PS) was compared using flow cytometry. Measurements of microvesicle phagocytosis by human monocytes were carried out using a flow cytometer and a confocal microscope.

RESULTS

The analysis of the microvesicles with calibration beads allowed us to identify these structures with a diameter of about 0·5 µm in the 'fresh' and 'old' samples. At day 2, the microvesicles had elevated expression levels of CD47, reduced expression levels of PS, CD55 and CD59. The phagocytosis index was higher for the microvesicles isolated from the 42-day-old erythrocyte concentrates.

CONCLUSION

This research may bring us closer to understanding the factors responsible for erythrocyte ageing and to evaluate the quality of stored red blood concentrates intended for transfusion.

The effect of splenectomy on complement regulatory proteins in erythrocytes in β-thalassemia major

INTRODUCTION

Hemolysis due to ineffective erythropoiesis is a serious problem β-thalassemia major (β-TM) patients. The role of complement system in the etiopathogenesis of hemolysis observed in β-TM were released. Hemolysis induced by activation of complement system is prevented by complement regulatory proteins. Decay accelerating factor (CD55), membrane inhibitor of reactive lysis (CD59), and complement reception 1 (CR1, CD35) are among these proteins. The absence of these proteins thus accounts for the increased susceptibility of erythrocytes to complement lysis. Splenomegaly and hypersplenism are common complications among thalassemia major patients necessitating splenectomy.

MATERIAL AND METHODS

In this study we investigated how splenectomy effects complement regulatory system in erythrocytes. We analysed CD35, CD55, and CD59 levels on erythrocytes in β-TM by flow cytometry.

RESULTS

The overall mean percentage of CD55 and CD35 positive RBCs of group 1 (22 β-TM with splenectomy) was significantly lower than group 2 (23 β-TM without splenectomy) and group 3 (healthy controls) (p < 0.05). The overall mean percentage CD59 positive RBCs of patients was no significantly different in all groups. The levels of CD35 and CD55 expression on the erythrocytes of splenectomized patients was significantly lower than non-splenectomized patients (p < 0.05).

CONCLUSIONS

Increased erythrocyte destruction and iron deposition in organs due to deficiency of these regulatory proteins may be the underlying mechanism of organ damage developing in β-TM patients.

Consequences of dysregulated complement regulators on red blood cells

The complement system represents the first line of defense that is involved in the clearance of pathogens, dying cells and immune complexes via opsonization, induction of an inflammatory response and the formation of a lytic pore. Red blood cells (RBCs) are very important for the delivery of oxygen to tissues and are continuously in contact with complement proteins in the blood plasma. To prevent complement activation on RBCs, various complement regulatory proteins can be found in plasma and on the cell membrane. RBCs are special cells without a nucleus and having a slightly different make-up of complement regulators than nucleated cells, as membrane cofactor protein (MCP) is not expressed and complement receptor 1 (CR1) is highly expressed. Decreased expression and/or function of complement regulatory proteins may result in unwanted complement activation and accelerated removal of RBCs. This review describes complement regulation on RBCs and the consequences when this regulation is out of balance.

Diminished presentation of complement regulatory protein CD55 on red blood cells from patients with hereditary haemolytic anaemias

INTRODUCTION

Hereditary haemolytic anaemias (HHA) encompass a heterogeneous group of anaemias characterized by decreased red blood cell survival. The aim of this study was to evaluate the status of red blood cell (RBC) surface molecules known or previously proposed to participate in preventing premature RBC clearance, analysing erythrocytes from patients with two types of HHA: hereditary spherocytosis (HS) and microcytosis.

MATERIAL/METHODS

Relative binding of five monoclonal antibodies (mAbs), anti-CD55, anti-CD59, anti-CD44, anti-CD47 and anti-CD58, was evaluated in erythrocytes of patients with HS and hereditary microcytosis, using flow cytometry. The amount of CD55 protein was assessed by semi-quantitative Western blots densitometry analysis.

RESULTS

The majority of both HS and microcytic patients demonstrated significant reduction of anti-CD55 binding by erythrocytes (average 23% and 19%, respectively, P < .001), with no concomitant anti-CD59-binding deficiency. Anti-CD44, anti-CD47 and anti-CD58 binding was within the healthy control range or was slightly decreased.

CONCLUSIONS

This study provides evidence supporting the presence of erythrocytes deficient in CD55 presentation in HS and hereditary microcytosis. Moreover, deficiency of CD55 antigen presentation on RBC does not correlate with the amount of CD55 in RBC membrane. Further studies using molecular techniques will clarify the exact participation of CD55 deficiency in premature RBC clearance in HHA.

Expression of CD55, CD59, and CD35 on red blood cells of β-thalassaemia patients

AIM OF THE STUDY

β-thalassaemia (β-Thal) is considered a severe, progressive haemolytic anaemia, which needs regular blood transfusions for life expectancy. Complement-mediated erythrocyte destruction can cause both intravascular and extravascular haemolysis. Complement regulatory proteins protect cells from such effects of the complement system. We aimed to perform quantitative analysis of membrane-bound complement regulators, CD55 (decay accelerating factor - DAF), CD35 (complement receptor type 1 - CR1), and CD59 (membrane attack complex inhibitory factor - MACIF) on peripheral red blood cells by flow cytometry.

MATERIAL AND METHODS

The present study was carried out on 47 β-thalassemia major (β-TM) patients, 20 β-thalassaemia intermedia (β-TI) patients, and 17 healthy volunteers as control subjects.

RESULTS

CD55 levels of β-TM patients (58.64 ±17.06%) were significantly decreased compared to β-TI patients (83.34 ±13.82%) and healthy controls (88.57 ±11.69%) (p < 0.01). CD59 levels of β-TM patients were not significantly different than β-TI patients and controls, but CD35 levels were significantly lower in the β-TM patients (3.56 ±4.87%) and β-TI patients (12.48 ±9.19%) than in the control group (39.98 ±15.01%) (p < 0.01).

CONCLUSIONS

Low levels of CD55 and CD35 in thalassaemia major patients indicates a role for them in the aetiopathogenesis of haemolysis in this disease, and also this defect in a complement system may be responsible for the chronic complications seen in these patients.

The role of complement activation in thrombosis and hemolytic anemias

OBJECTIVE

The objective of this study was to describe complement activation in hemostatic and pathologic states of coagulation and in the acquired and congenital hemolytic anemias.

METHODS AND RESULTS

We review published and emerging data on the involvement of the classic, alternative and lectin-based complement pathways in coagulation and the hemolytic anemias. The alternative pathway in particular is always "on," at low levels, and is particularly sensitive to hyper-activation in a variety of physiologic and pathologic states including infection, autoimmune disorders, thrombosis and pregnancy, requiring tight control predicated on a variety of soluble and membrane bound regulatory proteins. In acquired hemolytic anemias such as paroxysmal nocturnal hemoglobinuria (PNH) and cold agglutinin disease (CAD), the complement system directly induces red blood cell injury, resulting in intravascular and extravascular hemolysis. In congenital hemolytic anemias such as sickle cell disease and β-thalassemia, the complement system may also contribute to thrombosis and vascular disease. Complement activation may also lead to a storage lesion in red blood cells prior to transfusion.

CONCLUSION

Complement pathways are activated in hemolytic anemias and are closely linked with thrombosis. In acquired disorders such as PNH and possibly CAD, inhibition of the alternative complement pathway improves clinical outcomes and reduces thrombosis risk. Whether complement inhibition has a similar role in congenital hemolytic anemias apart from the atypical hemolytic-uremic (aHUS)-type thrombotic microangiopathies remains to be determined.