Red Blood Cell Metabolism In Vivo and In Vitro

Red blood cells (RBC) are the most abundant cell in the human body, with a central role in oxygen transport and its delivery to tissues. However, omics technologies recently revealed the unanticipated complexity of the RBC proteome and metabolome, paving the way for a reinterpretation of the mechanisms by which RBC metabolism regulates systems biology beyond oxygen transport. The new data and analytical tools also informed the dissection of the changes that RBCs undergo during refrigerated storage under blood bank conditions, a logistic necessity that makes >100 million units available for life-saving transfusions every year worldwide. In this narrative review, we summarize the last decade of advances in the field of RBC metabolism in vivo and in the blood bank in vitro, a narrative largely influenced by the authors' own journeys in this field. We hope that this review will stimulate further research in this interesting and medically important area or, at least, serve as a testament to our fascination with this simple, yet complex, cell.

Tubulin-mediated anatomical and functional changes caused by Ca2+ in human erythrocytes

In previous research, we observed that tubulin can be found in three fractions within erythrocytes, i.e., attached to the membrane, as a soluble fraction, or as part of a structure that can be sedimented by centrifugation. Given that its differential distribution within these fractions may alter several hemorheological properties, such as erythrocyte deformability, the present work studied how this distribution is in turn affected by Ca²⁺, another key player in the regulation of erythrocyte cytoskeleton stability. The effect of Ca²⁺ on some hemorheological parameters was also assessed. The results showed that when Ca²⁺ concentrations increased in the cell, whether by the addition of ionophore A23187, by specific plasma membrane Ca^2 + _ATPase (PMCA) inhibition, or due to arterial hypertension, tubulin translocate to the membrane, erythrocyte deformability decreased, and phosphatidylserine exposure increased. Moreover, increased Ca²⁺ was associated with an inverse correlation in the distribution of tubulin and spectrin, another important cytoskeleton protein. Based on these findings, we propose the existence of a mechanism of action through which higher Ca²⁺ concentrations in erythrocytes trigger the migration of tubulin to the membrane, a phenomenon that results in alterations of rheological and molecular aspects of the membrane itself, as well as of the integrity of the cytoskeleton.

Anticancer Drugs Paclitaxel, Carboplatin, Doxorubicin, and Cyclophosphamide Alter the Biophysical Characteristics of Red Blood Cells, In Vitro

Red blood cells (RBCs) are the most numerous cells in the body and perform gas exchange between all tissues. During the infusion of cancer chemotherapeutic (CT) agents, blood cells are the first ones to encounter aggressive cytostatics. Erythrocyte dysfunction caused by direct cytotoxic damage might be a part of the problem of chemotherapy-induced anemia-one of the most frequent side effects. The aim of the current study is to evaluate the functional status of RBCs exposed to mono and combinations of widely used commercial pharmaceutical CT drugs with different action mechanisms: paclitaxel, carboplatin, cyclophosphamide, and doxorubicin, in vitro. Using laser diffraction, flow cytometry, and confocal microscopy, we show that paclitaxel, having a directed effect on cytoskeleton proteins, by itself and in combination with carboplatin, caused the most marked abnormalities-loss of control of volume regulation, resistance to osmotic load, and stomatocytosis. Direct simulations of RBCs' microcirculation in microfluidic channels showed both the appearance of a subpopulation of cells with impaired velocity (slow damaged cells) and an increased number of cases of occlusions. In contrast to paclitaxel, such drugs as carboplatin, cyclophosphamide, and doxorubicin, whose main target in cancer cells is DNA, showed significantly less cytotoxicity to erythrocytes in short-term exposure. However, the combination of drugs had an additive effect. While the obtained results should be confirmed in in vivo models, one can envisioned that such data could be used for minimizing anemia side effects during cancer chemotherapy.

Identification of radiation responsive RBC membrane associated proteins (RMAPs) in whole-body γ-irradiated New Zealand white rabbits

This study is aimed to identify radiation-responsive RBC Membrane Associated Proteins (RMAPs) in Rabbits in vivo. Male New Zealand White rabbits were exposed to a single acute total body γ-radiation dose of 2 Gy at a dose rate of 0.746 Gy/min. Following this, at early time points of 6 h till the 7 d, RMAPs were collected and analyzed by MALDI-TOF-MS. Bioinformatics analysis was conducted to explore the biological functions of these proteins. Based on fold change, radiation responsiveness, GO, pathway enrichment, and hub position in the PPI network, we identified seven RMAPs as potential biomarker candidates viz., PVALB, PRKCB, GPD1, CP2G1, CSNK2B, ATP1B1, TPI1. As per KEGG enrichment, most of the proteins were implicated in cellular radiation response, oxidative damage, DNA repair, apoptosis, immune response, and cell signaling. This study forms the foundation for RMAPs-based Proteomic strategies for high throughput radiation bio-dosimetry for triage in the case of a radiological/nuclear incident.

p97 dysfunction underlies a loss of quality control of damaged membrane proteins and promotes oxidative stress and sickling in sickle cell disease

Sickling is the central pathogenic process of sickle cell disease (SCD), one of the most prevalent inherited hemolytic disorders. Having no easy access to antioxidants in the cytosol, elevated levels of reactive oxygen species (ROS) residing at the plasma membrane in sickle red blood cells (sRBCs) easily oxidize membrane proteins and thus contribute to sickling. Although the ubiquitin-proteasome system (UPS) is essential to rapidly clear ROS-damaged membrane proteins and maintain cellular homeostasis, the function and regulatory mechanism of the UPS for their clearance in sRBCs remains unidentified. Elevated levels of polyubiquitinated membrane-associated proteins in human sRBCs are reported here. High throughput and untargeted proteomic analyses of membrane proteins immunoprecipitated by ubiquitin antibodies detected elevated levels of ubiquitination of a series of proteins including cytoskeletal proteins, transporters, ROS-related proteins, and UPS machinery components in sRBCs. Polyubiquitination of membrane-associated catalase was increased in sRBCs, associated with decreased catalase activity and elevated ROS. Surprisingly, shuttling of p97 (ATP-dependent valosin-containing chaperone protein), a key component of the UPS to shuttle polyubiquitinated proteins from the membrane to cytosol for proteasomal degradation, was significantly impaired, resulting in significant accumulation of p97 along with polyubiquitinated proteins in the membrane of human sRBCs. Functionally, inhibition of p97 directly promoted accumulation of polyubiquitinated membrane-associated proteins, excessive ROS levels, and sickling in response to hypoxia. Overall, we revealed that p97 dysfunction underlies impaired UPS and contributes to oxidative stress in sRBCs.

Revisiting the question of nucleated versus enucleated erythrocytes in birds and mammals

Erythrocyte enucleation is thought to have evolved in mammals to support their energetic cost of high metabolic activities. However, birds face similar selection pressure yet possess nucleated erythrocytes. Current hypotheses on the mammalian erythrocyte enucleation claim that the absence of cell organelles allows erythrocytes to 1) pack more hemoglobin into the cells to increase oxygen carrying capacity and 2) decrease erythrocyte size for increased surface area-to-volume ratio, and improved ability to traverse small capillaries. In this article, we first empirically tested current hypotheses using both conventional and phylogenetically informed analysis comparing literature values of mean cell hemoglobin concentration (MCHC) and mean cell volume (MCV) between 181 avian and 194 mammalian species. We found no difference in MCHC levels between birds and mammals using both conventional and phylogenetically corrected analysis. MCV was higher in birds than mammals according to conventional analysis, but the difference was lost when we controlled for phylogeny. These results suggested that avian and mammalian erythrocytes may employ different strategies to solve a common problem. To further investigate existing hypotheses or develop new hypothesis, we need to understand the functions of various organelles in avian erythrocytes. Consequently, we covered potential physiological functions of various cell organelles in avian erythrocytes based on current knowledge, while making explicit comparisons to their mammalian counterparts. Finally, we proposed by taking an integrative and comparative approach, using tools from molecular biology to evolutionary biology, would allow us to better understand the fundamental physiological functions of various components of avian and mammalian erythrocytes.

Targeting spectrin redox switches to regulate the mechanoproperties of red blood cells

The mechanical properties of red blood cells (RBCs) are fundamental for their physiological role as gas transporters. RBC flexibility and elasticity allow them to survive the hemodynamic changes in the different regions of the vascular tree, to dynamically contribute to the flow thereby decreasing vascular resistance, and to deform during the passage through narrower vessels. RBC mechanoproperties are conferred mainly by the structural characteristics of their cytoskeleton, which consists predominantly of a spectrin scaffold connected to the membrane via nodes of actin, ankyrin and adducin. Changes in redox state and treatment with thiol-targeting molecules decrease the deformability of RBCs and affect the structure and stability of the spectrin cytoskeleton, indicating that the spectrin cytoskeleton may contain redox switches. In this perspective review, we revise current knowledge about the structural and functional characterization of spectrin cysteine redox switches and discuss the current lines of research aiming to understand the role of redox regulation on RBC mechanical properties. These studies may provide novel functional targets to modulate RBC function, blood viscosity and flow, and tissue perfusion in disease conditions.

Interventions for treating intrahepatic cholestasis in people with sickle cell disease

BACKGROUND

Sickle cell disease is the most common hemoglobinopathy occurring worldwide and sickle cell intrahepatic cholestasis is a complication long recognized in this population. Cholestatic liver diseases are characterized by impaired formation or excretion (or both) of bile from the liver. There is a need to assess the clinical benefits and harms of the interventions used to treat intrahepatic cholestasis in people with sickle cell disease. This is an update of a previously published Cochrane Review.

OBJECTIVES

To assess the benefits and harms of the interventions for treating intrahepatic cholestasis in people with sickle cell disease.

SEARCH METHODS

We searched the Cystic Fibrosis and Genetic Disorders Group's Haemoglobinopathies Trials Register, which comprises references identified from comprehensive electronic database searches and handsearching of relevant journals and abstract books of conference proceedings. We also searched the LILACS database (1982 to 21 January 2020), the WHO International Clinical Trials Registry Platform Search Portal and ClinicalTrials.gov (21 January 2020). Date of last search of the Cochrane Cystic Fibrosis and Genetic Disorders Group's Haemoglobinopathies Trials Register: 25 November 2019.

SELECTION CRITERIA

We searched for published or unpublished randomised controlled trials.

DATA COLLECTION AND ANALYSIS

Each author intended to independently extract data, assess the risk of bias of the trials by standard Cochrane methodologies and assess the quality of the evidence using the GRADE criteria; however, no trials were included in the review.

MAIN RESULTS

We did not identify any randomised controlled trials.

AUTHORS' CONCLUSIONS

This updated Cochrane Review did not identify any randomised controlled trials assessing interventions for treating intrahepatic cholestasis in people with sickle cell disease. Randomised controlled trials are needed to establish the optimum treatment for this condition.

Human erythrocytes: cytoskeleton and its origin

In the last few years, erythrocytes have emerged as the main determinant of blood rheology. In mammals, these cells are devoid of nuclei and are, therefore, unable to divide. Consequently, all circulating erythrocytes come from erythropoiesis, a process in the bone marrow in which several modifications are induced in the expression of membrane and cytoskeletal proteins, and different vertical and horizontal interactions are established between them. Cytoskeleton components play an important role in this process, which explains why they and the interaction between them have been the focus of much recent research. Moreover, in mature erythrocytes, the cytoskeleton integrity is also essential, because the cytoskeleton confers remarkable deformability and stability on the erythrocytes, thus enabling them to undergo deformation in microcirculation. Defects in the cytoskeleton produce changes in erythrocyte deformability and stability, affecting cell viability and rheological properties. Such abnormalities are seen in different pathologies of special interest, such as different types of anemia, hypertension, and diabetes, among others. This review highlights the main findings in mammalian erythrocytes and their progenitors regarding the presence, conformation and function of the three main components of the cytoskeleton: actin, intermediate filaments, and tubulin.

A Novel Method to Identify Autoantibodies against Putative Target Proteins in Serum from beta-Thalassemia Major: A Pilot Study

Abnormal immune reactivity in patients with beta-thalassemia (beta-thal) major can be associated with poor prognosis. Immunome protein-array analysis represents a powerful approach to identify novel biomarkers. The Sengenics Immunome Protein Array platform was used for high-throughput quantification of autoantibodies in 12 serum samples collected from nine beta-thal major patients and three non-thalassemia controls, which were run together with two pooled normal sera (Sengenics Internal QC samples). To obtain more accurate and reliable results, the evaluation of the biological relevance of the shortlisted biomarkers was analyzed using an Open Target Platform online database. Elevated autoantibodies directed against 23 autoantigens on the immunome array were identified and analyzed using a penetrance fold change-based bioinformatics method. Understanding the autoantibody profile of beta-thal major patients would help to further understand the pathogenesis of the disease. The identified autoantigens may serve as potential biomarkers for the prognosis of beta-thal major.

Optimizing red blood cell protein extraction for biomarker quantitation with mass spectrometry

Red blood cells (RBC) are the most common cell type found in blood. They might serve as reservoir for biomarker research as they are anuclear and lack the ability to synthesize proteins. Not many biomarker assays, however, have been conducted on RBC because of their large dynamic range of proteins, high abundance of lipids, and hemoglobin interferences. Here, we developed a semiquantitative mass spectrometry-based assay that targeted 144 proteins and compared the efficiency of urea, sodium deoxycholate, acetonitrile, and HemoVoid™ in their extraction of the RBC proteome. Our results indicate that protein extraction with HemoVoid™ led to hemoglobin reduction and increased detection of low abundance proteins. Although hemoglobin interference after deoxycholate and urea extraction was high, there were adequate amounts of low abundance proteins for quantitation. Extraction with acetonitrile led to an overall decrease in protein abundances probably as a result of precipitation. Overall, the best compromise in sensitivity and sample processing time was achieved with the urea-trypsin digestion protocol. This provided the basis for large-scale evaluations of protein targets as potential blood-based biomarkers. As a proof of concept, we applied this assay to determine that alpha-synuclein, a prominent marker in Parkinson's disease, has an average concentration of approximately 40 μg mL^-1 in RBC. This is important to know as the concentration of alpha-synuclein in plasma, typically in the picogram per milliliter range, might be partially derived from lysed RBC. Utilization of this assay will prove useful for future biomarker studies and provide a more complete analytical toolbox for the measurement of blood-derived proteins. Graphical abstract.

The Spectrinome: The Interactome of a Scaffold Protein Creating Nuclear and Cytoplasmic Connectivity and Function

We provide a review of Spectrin isoform function in the cytoplasm, the nucleus, the cell surface, and in intracellular signaling. We then discuss the importance of Spectrin’s E2/E3 chimeric ubiquitin conjugating and ligating activity in maintaining cellular homeostasis. Finally we present spectrin isoform subunit specific human diseases. We have created the Spectrinome, from the Human Proteome, Human Reactome and Human Atlas data and demonstrated how it can be a useful tool in visualizing and understanding spectrins myriad of cellular functions.

Impact statement

Spectrin was for the first 12 years after its discovery thought to be found only in erythrocytes. In 1981, Goodman and colleagues1found that spectrin-like molecules were ubiquitously found in non-erythroid cells leading to a great multitude of publications over the next thirty eight years. The discovery of multiple spectrin isoforms found associated with every cellular compartment, and representing 2-3% of cellular protein, has brought us to today’s understanding that spectrin is a scaffolding protein, with its own E2/E3 chimeric ubiquitin conjugating ligating activity that is involved in virtually every cellular function. We cover the history, localized functions of spectrin isoforms, human diseases caused by mutations, and provide the spectrinome: a useful tool for understanding the myriad of functions for one of the most important proteins in all eukaryotic cells.

Absolute proteome quantification of highly purified populations of circulating reticulocytes and mature erythrocytes

Reticulocytes produced in the bone marrow undergo maturation in the bloodstream to give rise to erythrocytes. Although the proteome of circulating red cells has been the subject of several reports, the cellular populations used for these studies were never completely devoid of reticulocytes. In our current study, we used highly purified erythrocyte and reticulocyte populations to quantify the absolute expression levels of the proteins in each cell population. Erythrocytes and reticulocytes were purified in a multistep process involving cellulose chromatography, Percoll gradient centrifugation, and fluorescence cell sorting after thiazole orange labeling. Proteins were analyzed by mass spectrometry from whole cells and erythrocyte plasma membrane (ghosts), leading to the identification and quantification of 2077 proteins, including 654 that were reticulocyte-specific. Absolute quantifications of these proteins were made using the mean corpuscular hemoglobin content of the cells as a standard. For each protein, we calculated the percentage loss during the terminal stages of reticulocyte maturation and the percentage of association with the plasma membrane. In addition, we used modified adenosine triphosphate and adenosine diphosphate molecules that enable the transfer of a biotin molecule to the catalytic sites of kinases to isolate active kinases in the erythrocytes and determined the absolute expression of 75 protein kinases and the modification of their expression during reticulocyte maturation. Our findings represent the first absolute quantification of proteins that are specifically expressed in normal erythrocytes with no detectable contamination by reticulocytes. Our findings thus represent a reference database for the future proteomic analysis of pathological erythrocytes.

Repository of Enriched Structures of Proteins Involved in the Red Blood Cell Environment (RESPIRE)

The Red Blood Cell (RBC) is a metabolically-driven cell vital for processes such a gas transport and homeostasis. RBC possesses at its surface exposing antigens proteins that are critical in blood transfusion. Due to their importance, numerous studies address the cell function as a whole but more and more details of RBC structure and protein content are now studied using massive state-of-the art characterisation techniques. Yet, the resulting information is frequently scattered in many scientific articles, in many databases and specialized web servers. To provide a more compendious view of erythrocytes and of their protein content, we developed a dedicated database called RESPIRE that aims at gathering a comprehensive and coherent ensemble of information and data about proteins in RBC. This cell-driven database lists proteins found in erythrocytes. For a given protein entry, initial data are processed from external portals and enriched by using state-of-the-art bioinformatics methods. As structural information is extremely useful to understand protein function and predict the impact of mutations, a strong effort has been put on the prediction of protein structures with a special treatment for membrane proteins. Browsing the database is available through text search for reference gene names or protein identifiers, through pre-defined queries or via hyperlinks. The RESPIRE database provides valuable information and unique annotations that should be useful to a wide audience of biologists, clinicians and structural biologists.

Database URL:http://www.dsimb.inserm.fr/respire

Red blood cells: The primary reservoir of macrophage migration inhibitory factor in whole blood

Red blood cells are widely accepted to be inert carriers of oxygen and haemoglobin, but there is growing evidence that they play a much more critical role in immune function. Macrophage migration inhibitory factor (MIF) is a key cytokine in disease with additional oxido-reductase activity, which aids in managing oxidative stress. Although two studies have reported the presence of MIF in red blood cells, no study has quantified the levels of this protein. In this study, freshly isolated plasma, platelets, leukocytes, and red blood cells from healthy individuals were collected and the concentration of MIF was determined using an enzyme linked immunosorbent assay. This analysis demonstrated that MIF in red blood cells was present at 25 µg per millilitre of whole blood, which is greater than99% of the total MIF and 1000-fold higher concentration than plasma. This result was supported by electrophoresis and Western blot analysis, which identified MIF in its monomer structural form following sample processing. Furthermore, by assessing the level of tautomerase activity in red blood cell fractions in the presence of a MIF inhibitor, it was determined that the red blood cell-derived MIF was also functionally active. Together, these findings have implications on the effect of haemolysis during sample preparation and provide some clue into the inflammatory processes that occur following haemolysis in vivo. These results support the hypothesis that red blood cells are a major reservoir of this inflammatory protein and may play a role in inflammation.

Tubulin is retained throughout the human hematopoietic/erythroid cell differentiation process and plays a structural role in sedimentable fraction of mature erythrocytes

We investigated the properties of tubulin present in the sedimentable fraction ("Sed-tub") of human erythrocytes, and tracked the location and organization of tubulin in various types of cells during the process of hematopoietic/erythroid differentiation. Sed-tub was sensitive to taxol/nocodazole (drugs that modify microtubule assembly/disassembly), but was organized as part of a protein network rather than in typical microtubule form. This network had a non-uniform "connected-ring" structure, with tubulin localized in the connection areas and associated with other proteins. When tubulin was eliminated from Sed-tub fraction, this connected-ring structure disappeared. Spectrin, a major protein component in Sed-tub fraction, formed a complex with tubulin. During hematopoietic differentiation, tubulin shifts from typical microtubule structure (in pro-erythroblasts) to a disorganized structure (in later stages), and is retained in reticulocytes following enucleation. Thus, tubulin is not completely lost when erythrocytes mature; it continues to play a structural role in the Sed-tub fraction.

Protein-Protein Interaction Probed by Label-free Second Harmonic Light Scattering: Hemoglobin Adsorption on Spectrin Surface as a Case Study

In this article, we have studied the binding of different naturally occurring hemoglobin (Hb) variants on erythrocyte skeletal protein, spectrin surface using the label free nondestructive second harmonic light scattering (SHLS) technique in aqueous buffer. Hemoglobin variants like sickle hemoglobin (HbS) and hemoglobin E (HbE) were chosen as they associate with sickle cell disease and HbEβ-thalassemia, respectively, and their interaction with spectrin is compared with normal adult hemoglobin (HbA). The concentration dependent change in the second harmonic light intensity from nanomolar spectrin solution has been measured after addition of small aliquots of hemoglobins. From the second harmonic titration data, the binding constant is calculated using a modified Langmuir adsorption model of hemoglobin binding to the spectrin surface. Interestingly, it is found that the binding constant for HbE (13.8 × 10⁸ M^-1) is 1 order of magnitude higher than that of HbS (1.6 × 10⁸ M^-1) or HbA (2.1 × 10⁸ M^-1) which indicates higher affinity of HbE for spectrin compared to HbA and HbS. The number of the Hb molecules bound to the spectrin surface was estimated to be of the order of hundred's which is determined for the first time.

Interventions for treating intrahepatic cholestasis in people with sickle cell disease

BACKGROUND

Sickle cell disease is the most common hemoglobinopathy occurring worldwide and sickle cell intrahepatic cholestasis is a complication long recognized in this population. Cholestatic liver diseases are characterized by impaired formation or excretion (or both) of bile from the liver. There is a need to assess the clinical benefits and harms of the interventions used to treat intrahepatic cholestasis in people with sickle cell disease. This is an update of a previously published Cochrane Review.

OBJECTIVES

To assess the benefits and harms of the interventions for treating intrahepatic cholestasis in people with sickle cell disease.

SEARCH METHODS

We searched the Cystic Fibrosis and Genetic Disorders Group's Haemoglobinopathies Trials Register, which comprises references identified from comprehensive electronic database searches and handsearching of relevant journals and abstract books of conference proceedings. We also searched the LILACS database (1982 to 23 May 2017), the WHO International Clinical Trials Registry Platform Search Portal (23 May 2017) and ClinicalTrials.gov.Date of last search of the Cochrane Cystic Fibrosis and Genetic Disorders Group's Haemoglobinopathies Trials Register: 12 April 2017.

SELECTION CRITERIA

We searched for published or unpublished randomised controlled trials.

DATA COLLECTION AND ANALYSIS

Each author intended to independently extract data and assess the risk of bias of the trials by standard Cochrane methodologies; however, no trials were included in the review.

MAIN RESULTS

There were no randomised controlled trials identified.

AUTHORS' CONCLUSIONS

This updated Cochrane Review did not identify any randomised controlled trials assessing interventions for treating intrahepatic cholestasis in people with sickle cell disease. Randomised controlled trials are needed to establish the optimum treatment for this condition.

Proteomic analysis of red blood cells from donors exhibiting high hemolysis demonstrates a reduction in membrane-associated proteins involved in the oxidative response

BACKGROUND

The development of hemolysis during ex vivo hypothermic storage is multifaceted. Standardization of collection and production processes is used to minimize variability in biologics manufacturing and to maximize product quality. However, the influence of various donor characteristics on product quality is often difficult to evaluate and to control. Using a proteomic approach, we aimed to decipher relevant donor characteristics that may predict red blood cell (RBC) quality during storage.

STUDY DESIGN AND METHODS

Ten healthy volunteer donors exhibiting repeated high hemolysis at outdate (>0.8%; RBC^HH ) and 10 age- and sex-matched control donors (RBC^Ctrl ) were studied. Common quality variables were measured on Days 5, 14, 21, 28, and 42 of storage. Protein profiles of hemoglobin-depleted membrane fractions from RBC^HH and RBC^Ctrl donors were analyzed using a quantitative proteomics approach based on iTRAQ (isobaric tags for relative and absolute quantitation).

RESULTS

Time-dependent lesion development was apparent in both donor populations. RBC^HH exhibited reduced 2,3-bisphosphoglycerate levels (p < 0.001) and morphologic score (p < 0.001), but displayed elevated hemolysis level (p < 0.001), RBC-derived microvesicle formation (p < 0.001), and mean corpuscular fragility (p < 0.001) compared to RBC^Ctrl , indicating notable differences at the membrane between the two donor populations. Proteomic findings revealed a significant reduction in the level of proteins involved in oxidative response pathways at early time points in RBC^HH compared to that of RBC^Ctrl .

CONCLUSION

The recruitment of these candidate proteins might be part of a response mechanism altered in RBC^HH donors and therefore may be useful as a donor screening tool.

Cdk6 contributes to cytoskeletal stability in erythroid cells

Mice lacking Cdk6 kinase activity suffer from mild anemia accompanied by elevated numbers of Ter119⁺ cells in the bone marrow. The animals show hardly any alterations in erythroid development, indicating that Cdk6 is not required for proliferation and maturation of erythroid cells. There is also no difference in stress erythropoiesis following hemolysis in vivo. However, Cdk6^−/− erythrocytes have a shortened lifespan and are more sensitive to mechanical stress in vitro, suggesting differences in cytoskeletal architecture. Erythroblasts contain both Cdk4 and Cdk6, while mature erythrocytes apparently lack Cdk4 and their Cdk6 is partly associated with the cytoskeleton. We used mass spectrometry to show that Cdk6 interacts with a number of proteins involved in cytoskeleton organization. Cdk6^−/− erythroblasts show impaired F-actin formation and lower levels of gelsolin, which interacts with Cdk6. We also found that Cdk6 regulates the transcription of a panel of genes involved in actin (de-)polymerization. Cdk6-deficient cells are sensitive to drugs that interfere with the cytoskeleton, suggesting that our findings are relevant to the treatment of patients with anemia – and may be relevant to cancer patients treated with the new generation of CDK6 inhibitors.

Proteomic analysis of red blood cells and the potential for the clinic: what have we learned so far?

INTRODUCTION

Red blood cells (RBC) are the most abundant host cells in the human body. Mature erythrocytes are devoid of nuclei and organelles and have always been regarded as circulating 'bags of hemoglobin'. The advent of proteomics has challenged this assumption, revealing unanticipated complexity and novel roles for RBCs not just in gas transport, but also in systemic metabolic homeostasis in health and disease. Areas covered: In this review we will summarize the main advancements in the field of discovery mode and redox/quantitative proteomics with respect to RBC biology. We thus focus on translational/clinical applications, such as transfusion medicine, hematology (e.g. hemoglobinopathies) and personalized medicine. Synergy of omics technologies - especially proteomics and metabolomics - are highlighted as a hallmark of clinical metabolomics applications for the foreseeable future. Expert commentary: The introduction of advanced proteomics technologies, especially quantitative and redox proteomics, and the integration of proteomics data with omics information gathered through orthogonal technologies (especially metabolomics) promise to revolutionize many biomedical areas, from hematology and transfusion medicine to personalized medicine and clinical biochemistry.

The Proteome of the Red Blood Cell: An Auspicious Source of New Insights into Membrane-Centered Regulation of Homeostasis

During the past decade, the hand-in-hand development of biotechnology and bioinformatics has enabled a view of the function of the red blood cell that surpasses the supply of oxygen and removal of carbon dioxide. Comparative proteomic inventories have yielded new clues to the processes that regulate membrane-cytoskeleton interactions in health and disease, and to the ways by which red blood cells communicate with their environment. In addition, proteomic data have revealed the possibility that many, hitherto unsuspected, metabolic processes are active in the red blood cell cytoplasm. Recent metabolomic studies have confirmed and expanded this notion. Taken together, the presently available data point towards the red blood cell membrane as the hub at which all regulatory processes come together. Thus, alterations in the association of regulatory proteins with the cell membrane may be a sine qua non for the functional relevance of any postulated molecular mechanism. From this perspective, comparative proteomics centered on the red blood cell membrane constitute a powerful tool for the identification and elucidation of the physiologically and pathologically relevant pathways that regulate red blood cell homeostasis. Additionally, this perspective provides a focus for the interpretation of metabolomic studies, especially in the development of biomarkers in the blood.

Multi-omics Evidence for Inheritance of Energy Pathways in Red Blood Cells

Each year over 90 million units of blood are transfused worldwide. Our dependence on this blood supply mandates optimized blood management and storage. During storage, red blood cells undergo degenerative processes resulting in altered metabolic characteristics which may make blood less viable for transfusion. However, not all stored blood spoils at the same rate, a difference that has been attributed to variable rates of energy usage and metabolism in red blood cells. Specific metabolite abundances are heritable traits; however, the link between heritability of energy metabolism and red blood cell storage profiles is unclear. Herein we performed a comprehensive metabolomics and proteomics study of red blood cells from 18 mono- and di-zygotic twin pairs to measure heritability and identify correlations with ATP and other molecular indices of energy metabolism. Without using affinity-based hemoglobin depletion, our work afforded the deepest multi-omic characterization of red blood cell membranes to date (1280 membrane proteins and 330 metabolites), with 119 membrane protein and 148 metabolite concentrations found to be over 30% heritable. We demonstrate a high degree of heritability in the concentration of energy metabolism metabolites, especially glycolytic metabolites. In addition to being heritable, proteins and metabolites involved in glycolysis and redox metabolism are highly correlated, suggesting that crucial energy metabolism pathways are inherited en bloc at distinct levels. We conclude that individuals can inherit a phenotype composed of higher or lower concentrations of these proteins together. This can result in vastly different red blood cells storage profiles which may need to be considered to develop precise and individualized storage options. Beyond guiding proper blood storage, this intimate link in heritability between energy and redox metabolism pathways may someday prove useful in determining the predisposition of an individual toward metabolic diseases.

Donor-variation effect on red blood cell storage lesion: A close relationship emerges

Although the molecular pathways leading to the progressive deterioration of stored red blood cells (RBC storage lesion) and the clinical relevance of storage-induced changes remain uncertain, substantial donor-specific variability in RBC performance during storage, and posttransfusion has been established ("donor-variation effect"). In-bag hemolysis and numerous properties of the RBC units that may affect transfusion efficacy have proved to be strongly donor-specific. Donor-variation effect may lead to the production of highly unequal blood labile products even when similar storage strategy and duration are applied. Genetic, undiagnosed/subclinical medical conditions and lifestyle factors that affect RBC characteristics at baseline, including RBC lifespan, energy metabolism, and sensitivity to oxidative stress, are all likely to influence the storage capacity of individual donors' cells, although not evident by the donor's health or hematological status at blood donation. Consequently, baseline characteristics of the donors, such as membrane peroxiredoxin-2 and serum uric acid concentration, have been proposed as candidate biomarkers of storage quality. This review article focuses on specific factors that might contribute to the donor-variation effect and emphasizes the emerging need for using omics-based technologies in association with in vitro and in vivo transfusion models and clinical trials to discover biomarkers of storage quality and posttransfusion recovery in donor blood.

Minireview: Multiomic candidate biomarkers for clinical manifestations of sickle cell severity: Early steps to precision medicine

In this review, we provide a description of those candidate biomarkers which have been demonstrated by multiple-omics approaches to vary in correlation with specific clinical manifestations of sickle cell severity. We believe that future clinical analyses of severity phenotype will require a multiomic analysis, or an omics stack approach, which includes integrated interactomics. It will also require the analysis of big data sets. These candidate biomarkers, whether they are individual or panels of functionally linked markers, will require future validation in large prospective and retrospective clinical studies. Once validated, the hope is that informative biomarkers will be used for the identification of individuals most likely to experience severe complications, and thereby be applied for the design of patient-specific therapeutic approaches and response to treatment. This would be the beginning of precision medicine for sickle cell disease.

Plasmodiumfalciparum infection induces dynamic changes in the erythrocyte phospho-proteome

The phosphorylation status of red blood cell proteins is strongly altered during the infection by the malaria parasite Plasmodium falciparum. We identify the key phosphorylation events that occur in the erythrocyte membrane and cytoskeleton during infection, by a comparative analysis of global phospho-proteome screens between infected (obtained at schizont stage) and uninfected RBCs. The meta-analysis of reported mass spectrometry studies revealed a novel compendium of 495 phosphorylation sites in 182 human proteins with regulatory roles in red cell morphology and stability, with about 25% of these sites specific to infected cells. A phosphorylation motif analysis detected 7 unique motifs that were largely mapped to kinase consensus sequences of casein kinase II and of protein kinase A/protein kinase C. This analysis highlighted prominent roles for PKA/PKC involving 78 phosphorylation sites. We then compared the phosphorylation status of PKA (PKC) specific sites in adducin, dematin, Band 3 and GLUT-1 in uninfected RBC stimulated or not by cAMP to their phosphorylation status in iRBC. We showed cAMP-induced phosphorylation of adducin S59 by immunoblotting and we were able to demonstrate parasite-induced phosphorylation for adducin S726, Band 3 and GLUT-1, corroborating the protein phosphorylation status in our erythrocyte phosphorylation site compendium.

Erythrocyte and platelet proteomics in hematological disorders

Erythrocytes undergo ineffective erythropoesis, hemolysis, and premature eryptosis in sickle cell disease and thalassemia. Abnormal hemoglobin variants associated with hemoglobinopathy lead to vesiculation, membrane instability, and loss of membrane asymmetry with exposal of phosphatidylserine. This potentiates thrombin generation resulting in activation of the coagulation cascade responsible for subclinical phenotypes. Platelet activation also results in the release of microparticles, which express and transfer functional receptors from platelet membrane, playing key roles in vascular reactivity and activation of intracellular signaling pathways. Over the last decade, proteomics had proven to be an important field of research in studies of blood and blood diseases. Blood cells and its fluidic components have been proven to be easy systems for studying differential expressions of proteins in hematological diseases encompassing hemoglobinopathies, different types of anemias, myeloproliferative disorders, and coagulopathies. Proteomic studies of erythrocytes and platelets reported from several groups have highlighted various factors that intersect the signaling networks in these anucleate systems. In this review, we have elaborated on the current scenario of anucleate blood cell proteomes in normal and diseased individuals and the cross-talk between the two major constituent cell types of circulating blood.

Recent progress on lipid lateral heterogeneity in plasma membranes: From rafts to submicrometric domains

The concept of transient nanometric domains known as lipid rafts has brought interest to reassess the validity of the Singer-Nicolson model of a fluid bilayer for cell membranes. However, this new view is still insufficient to explain the cellular control of surface lipid diversity or membrane deformability. During the past decades, the hypothesis that some lipids form large (submicrometric/mesoscale vs nanometric rafts) and stable (>min vs s) membrane domains has emerged, largely based on indirect methods. Morphological evidence for stable submicrometric lipid domains, well-accepted for artificial and highly specialized biological membranes, was further reported for a variety of living cells from prokaryot es to yeast and mammalian cells. However, results remained questioned based on limitations of available fluorescent tools, use of poor lipid fixatives, and imaging artifacts due to non-resolved membrane projections. In this review, we will discuss recent evidence generated using powerful and innovative approaches such as lipid-specific toxin fragments that support the existence of submicrometric domains. We will integrate documented mechanisms involved in the formation and maintenance of these domains, and provide a perspective on their relevance on membrane deformability and regulation of membrane protein distribution.

Metabolomics in transfusion medicine

Biochemical investigations on the regulatory mechanisms of red blood cell (RBC) and platelet (PLT) metabolism have fostered a century of advances in the field of transfusion medicine. Owing to these advances, storage of RBCs and PLT concentrates has become a lifesaving practice in clinical and military settings. There, however, remains room for improvement, especially with regard to the introduction of novel storage and/or rejuvenation solutions, alternative cell processing strategies (e.g., pathogen inactivation technologies), and quality testing (e.g., evaluation of novel containers with alternative plasticizers). Recent advancements in mass spectrometry-based metabolomics and systems biology, the bioinformatics integration of omics data, promise to speed up the design and testing of innovative storage strategies developed to improve the quality, safety, and effectiveness of blood products. Here we review the currently available metabolomics technologies and briefly describe the routine workflow for transfusion medicine-relevant studies. The goal is to provide transfusion medicine experts with adequate tools to navigate through the otherwise overwhelming amount of metabolomics data burgeoning in the field during the past few years. Descriptive metabolomics data have represented the first step omics researchers have taken into the field of transfusion medicine. However, to up the ante, clinical and omics experts will need to merge their expertise to investigate correlative and mechanistic relationships among metabolic variables and transfusion-relevant variables, such as 24-hour in vivo recovery for transfused RBCs. Integration with systems biology models will potentially allow for in silico prediction of metabolic phenotypes, thus streamlining the design and testing of alternative storage strategies and/or solutions.

Red blood cell storage in additive solution-7 preserves energy and redox metabolism: a metabolomics approach

BACKGROUND

Storage and transfusion of red blood cells (RBCs) has a huge medical and economic impact. Routine storage practices can be ameliorated through the implementation of novel additive solutions (ASs) that tackle the accumulation of biochemical and morphologic lesion during routine cold liquid storage in the blood bank, such as the recently introduced alkaline solution AS-7. Here we hypothesize that AS-7 might exert its beneficial effects through metabolic modulation during routine storage.

STUDY DESIGN AND METHODS

Apheresis RBCs were resuspended either in control AS-3 or experimental AS-7, before ultrahigh-performance liquid chromatography-mass spectrometry metabolomics analysis.

RESULTS

Unambiguous assignment and relative quantitation was achieved for 229 metabolites. AS-3 and AS-7 results in many similar metabolic trends over storage, with AS-7 RBCs being more metabolically active in the first storage week. AS-7 units had faster fueling of the pentose phosphate pathway, higher total glutathione pools, and increased flux through glycolysis as indicated by higher levels of pathway intermediates. Metabolite differences are especially observed at 7 days of storage, but were still maintained throughout 42 days.

CONCLUSION

AS-7 formulation (chloride free and bicarbonate loading) appears to improve energy and redox metabolism in stored RBCs in the early storage period, and the differences, though diminished, are still appreciable by Day 42. Energy metabolism and free fatty acids should be investigated as potentially important determinants for preservation of RBC structure and function. Future studies will be aimed at identifying metabolites that correlate with in vitro and in vivo circulation times.

Proteome analysis of the triton-insoluble erythrocyte membrane skeleton

Erythrocyte shape and membrane integrity is imparted by the membrane skeleton, which can be isolated as a Triton X-100 insoluble structure that retains the biconcave shape of intact erythrocytes, indicating isolation of essentially intact membrane skeletons. These erythrocyte "Triton Skeletons" have been studied morphologically and biochemically, but unbiased proteome analysis of this substructure of the membrane has not been reported. In this study, different extraction buffers and in-depth proteome analyses were used to more fully define the protein composition of this functionally critical macromolecular complex. As expected, the major, well-characterized membrane skeleton proteins and their associated membrane anchors were recovered in good yield. But surprisingly, a substantial number of additional proteins that are not considered in erythrocyte membrane skeleton models were recovered in high yields, including myosin-9, lipid raft proteins (stomatin, flotillin1 and 2), multiple chaperone proteins (HSPs, protein disulfide isomerase and calnexin), and several other proteins. These results show that the membrane skeleton is substantially more complex than previous biochemical studies indicated, and it apparently has localized regions with unique protein compositions and functions. This comprehensive catalog of the membrane skeleton should lead to new insights into erythrocyte membrane biology and pathogenic mutations that perturb membrane stability. Biological significance Current models of erythrocyte membranes describe fairly simple homogenous structures that are incomplete. Proteome analysis of the erythrocyte membrane skeleton shows that it is quite complex and includes a substantial number of proteins whose roles and locations in the membrane are not well defined. Further elucidation of interactions involving these proteins and definition of microdomains in the membrane that contain these proteins should yield novel insights into how the membrane skeleton produces the normal biconcave erythrocyte shape and how it is perturbed in pathological conditions that destabilize the membrane.

Spectrin's chimeric E2/E3 enzymatic activity

In this minireview, we cover the discovery of the human erythrocyte α spectrin E2/E3 ubiquitin conjugating/ligating enzymatic activity and the specific cysteines involved. We then discuss the consequences when this activity is partially inhibited in sickle cell disease and the possibility that the same attenuation is occurring in multiple organ dysfunction syndrome. We finish by discussing the reasons for believing that nonerythroid α spectrin isoforms (I and II) also have this activity and the importance of testing this hypothesis. If correct, this would suggest that the nonerythroid spectrin isoforms play a major role in protein ubiquitination in all cell types. This would open new fields in experimental biology focused on uncovering the impact that this enzymatic activity has upon protein-protein interactions, protein turnover, cellular signaling, and many other functions impacted by spectrin, including DNA repair.

Inconsistencies in the red blood cell membrane proteome analysis: generation of a database for research and diagnostic applications

Based on recent results, the determination of the easily accessible red blood cell (RBC) membrane proteins may provide new diagnostic possibilities for assessing mutations, polymorphisms or regulatory alterations in diseases. However, the analysis of the current mass spectrometry-based proteomics datasets and other major databases indicates inconsistencies-the results show large scattering and only a limited overlap for the identified RBC membrane proteins. Here, we applied membrane-specific proteomics studies in human RBC, compared these results with the data in the literature, and generated a comprehensive and expandable database using all available data sources. The integrated web database now refers to proteomic, genetic and medical databases as well, and contains an unexpected large number of validated membrane proteins previously thought to be specific for other tissues and/or related to major human diseases. Since the determination of protein expression in RBC provides a method to indicate pathological alterations, our database should facilitate the development of RBC membrane biomarker platforms and provide a unique resource to aid related further research and diagnostics.

Platelet and red blood cell interactions and their role in rheumatoid arthritis

Cytokines, lymphocytes, platelets and several biomolecules have long been implicated in the pathology of rheumatoid arthritis (RA), and the influences of antibody production and tagging, and cytokine, chemokine and enzyme production at specific rheumatoid joints were thought to be exclusive to the advancement of disease parameters. Another role player in RA is red blood cells (RBCs) which, of late, have been found to be involved in RA pathobiology, as there is a positive correlation between RBC counts and joint pathology, as well as with inflammatory biomarkers in the disease. There is also an association between RBC distribution width and the incidence of myocardial infarction amongst RA patients, and there is a change in the lipid distribution within RBC membranes. Of late, certain RBC-associated factors with previously obscure roles and cell-derived particles thought to be inconsequential to the other constituents of plasma were found to be active biomolecular players. Several of these have been discovered to be present in or originating from RBCs. Their influences have been shown to involve in membrane dynamics that cause structural and functional changes in both platelets and RBCs. RBC-derived microparticles are emerging entities found to play direct roles in immunomodulation via interactions with other plasma cells. These correlations highlight the direct influences of RBCs on exacerbating RA pathology. This review will attempt to shed more light on how RBCs, in the true inflammatory milieu of RA, are playing an even greater role than previously assumed.

Malaria parasites produce volatile mosquito attractants

The malaria parasite Plasmodium falciparum contains a nonphotosynthetic plastid organelle that possesses plant-like metabolic pathways. Plants use the plastidial isoprenoid biosynthesis pathway to produce volatile odorants, known as terpenes. In this work, we describe the volatile chemical profile of cultured malaria parasites. Among the identified compounds are several plant-like terpenes and terpene derivatives, including known mosquito attractants. We establish the molecular identity of the odorant receptors of the malaria mosquito vector Anopheles gambiae, which responds to these compounds. The malaria parasite produces volatile signals that are recognized by mosquitoes and may thereby mediate host attraction and facilitate transmission.

IMPORTANCE

Malaria is a key global health concern. Mosquitoes that transmit malaria are more attracted to malaria parasite-infected mammalian hosts. These studies aimed to understand the chemical signals produced by malaria parasites; such an understanding may lead to new transmission-blocking strategies or noninvasive malaria diagnostics.

Interventions for treating intrahepatic cholestasis in people with sickle cell disease

BACKGROUND

Sickle cell disease is the most common hemoglobinopathy occurring worldwide and sickle cell intrahepatic cholestasis is a complication long recognized in this population. Cholestatic liver diseases are characterized by impaired formation or excretion (or both) of bile from the liver. There is a need to assess the clinical benefits and harms of the interventions used to treat intrahepatic cholestasis in people with sickle cell disease.

OBJECTIVES

To assess the benefits and harms of the interventions for treating intrahepatic cholestasis in people with sickle cell disease.

SEARCH METHODS

We searched the Cystic Fibrosis and Genetic Disorders Group's Haemoglobinopathies Trials Register, which comprises references identified from comprehensive electronic database searches and handsearching of relevant journals and abstract books of conference proceedings. We also searched the LILACS database (1982 to 7 July 2014) and the WHO International Clinical Trials Registry Platform Search Portal (7 July 2014).Date of last search of the Cochrane Cystic Fibrosis and Genetic Disorders Group's Haemoglobinopathies Trials Register: 10 October 2014.

SELECTION CRITERIA

We searched for published or unpublished randomised controlled trials.

DATA COLLECTION AND ANALYSIS

Each author intended to independently extract data and assess the risk of bias of the trials by standard Cochrane Collaboration methodologies; however, no trials were included in the review.

MAIN RESULTS

There were no randomised controlled trials identified.

AUTHORS' CONCLUSIONS

This Cochrane Review did not identify any randomised controlled trials assessing interventions for treating intrahepatic cholestasis in people with sickle cell disease. Randomised controlled trials are needed to establish the optimum treatment for this condition.

More than hemoglobin - the unexpected diversity of globins in vertebrate red blood cells

In many multicellular organisms, oxygen is transported by respiratory proteins, which are globins in vertebrates, between respiratory organs and tissues. In jawed vertebrates, eight globins are known which are expressed in a highly tissue-specific manner. Until now, hemoglobin (Hb) had been agreed to be the only globin expressed in vertebrate erythrocytes. Here, we investigate for the first time the mRNA expression of globin genes in nucleated and anucleated erythrocytes of model vertebrate species by quantitative real-time reverse transcription PCR (qRT-PCR). Surprisingly, we found transcripts of the whole gnathostome globin superfamily in RBCs. The mRNA expression levels varied among species, with Hb being by far the dominant globin. Only in stickleback, a globin previously thought to be neuron-specific, neuroglobin, had higher mRNA expression. We furthermore show that in birds transcripts of globin E, which was earlier reported to be transcribed only in the eye, are also present in RBCs. Even in anucleated RBCs of mammals, we found transcripts of myoglobin, neuroglobin, and cytoglobin. Our findings add new aspects to the current knowledge on the expression of globins in vertebrate tissues. However, whether or not the mRNA expression of these globin genes has any functional significance in RBCs has to be investigated in future studies.

Routine storage of red blood cell (RBC) units in additive solution-3: a comprehensive investigation of the RBC metabolome

BACKGROUND

In most countries, red blood cells (RBCs) can be stored up to 42 days before transfusion. However, observational studies have suggested that storage duration might be associated with increased morbidity and mortality. While clinical trials are under way, impaired metabolism has been documented in RBCs stored in several additive solutions (ASs). Here we hypothesize that, despite reported beneficial effects, storage in AS-3 results in metabolic impairment weeks before the end of the unit shelf life.

STUDY DESIGN AND METHODS

Five leukofiltered AS-3 RBC units were sampled before, during, and after leukoreduction Day 0 and then assayed on a weekly basis from storage Day 1 through Day 42. RBC extracts and supernatants were assayed using a ultra-high-performance liquid chromatography separations coupled online with mass spectrometry detection metabolomics workflow.

RESULTS

Blood bank storage significantly affects metabolic profiles of RBC extracts and supernatants by Day 14. In addition to energy and redox metabolism impairment, intra- and extracellular accumulation of amino acids was observed proportionally to storage duration, suggesting a role for glutamine and serine metabolism in aging RBCs.

CONCLUSION

Metabolomics of stored RBCs could drive the introduction of alternative ASs to address some of the storage-dependent metabolic lesions herein reported, thereby increasing the quality of transfused RBCs and minimizing potential links to patient morbidity.

Plasmodium vivax trophozoite-stage proteomes

Plasmodium vivax is the causative infectious agent of 80-300 million annual cases of malaria. Many aspects of this parasite's biology remain unknown. To further elucidate the interaction of P. vivax with its Saimiri boliviensis host, we obtained detailed proteomes of infected red blood cells, representing the trophozoite-enriched stage of development. Data from two of three biological replicate proteomes, emphasized here, were analyzed using five search engines, which enhanced identifications and resulted in the most comprehensive P. vivax proteomes to date, with 1375 P. vivax and 3209 S. boliviensis identified proteins. Ribosome subunit proteins were noted for both P. vivax and S. boliviensis, consistent with P. vivax's known reticulocyte host-cell specificity. A majority of the host and pathogen proteins identified belong to specific functional categories, and several parasite gene families, while 33% of the P. vivax proteins have no reported function. Hemoglobin was significantly oxidized in both proteomes, and additional protein oxidation and nitration was detected in one of the two proteomes. Detailed analyses of these post-translational modifications are presented. The proteins identified here significantly expand the known P. vivax proteome and complexity of available host protein functionality underlying the host-parasite interactive biology, and reveal unsuspected oxidative modifications that may impact protein function.

BIOLOGICAL SIGNIFICANCE

Plasmodium vivax malaria is a serious neglected disease, causing an estimated 80 to 300 million cases annually in 95 countries. Infection can result in significant morbidity and possible death. P. vivax, unlike the much better-studied Plasmodium falciparum species, cannot be grown in long-term culture, has a dormant form in the liver called the hypnozoite stage, has a reticulocyte host-cell preference in the blood, and creates caveolae vesicle complexes at the surface of the infected reticulocyte membranes. Studies of stage-specific P. vivax expressed proteomes have been limited in scope and focused mainly on pathogen proteins, thus limiting understanding of the biology of this pathogen and its host interactions. Here three P. vivax proteomes are reported from biological replicates based on purified trophozoite-infected reticulocytes from different Saimiri boliviensis infections (the main non-human primate experimental model for P. vivax biology and pathogenesis). An in-depth analysis of two of the proteomes using 2D LC/MS/MS and multiple search engines identified 1375 pathogen proteins and 3209 host proteins. Numerous functional categories of both host and pathogen proteins were identified, including several known P. vivax protein family members (e.g., PHIST, eTRAMP and VIR), and 33% of protein identifications were classified as hypothetical. Ribosome subunit proteins were noted for both P. vivax and S. boliviensis, consistent with this parasite species' known reticulocyte host-cell specificity. In two biological replicates analyzed for post-translational modifications, hemoglobin was extensively oxidized, and various other proteins were also oxidized or nitrated in one of the two replicates. The cause of such protein modification remains to be determined but could include oxidized heme and oxygen radicals released from the infected red blood cell's parasite-induced acidic digestive vacuoles. In any case, the data suggests the presence of distinct infection-specific conditions whereby both the pathogen and host infected red blood cell proteins may be subject to significant oxidative stress.

Proteomic and biomarker studies and neurological complications of pediatric sickle cell disease

Biomarker analysis and proteomic discovery in pediatric sickle cell disease has the potential to lead to important discoveries and improve care. The aim of this review article is to describe proteomic and biomarker articles involving neurological and developmental complications in this population. A systematic review was conducted to identify relevant research publications. Articles were selected for children under the age of 21 years with the most common subtypes of sickle cell disease. Included articles focused on growth factors (platelet-derived growth factor), intra and extracellular brain proteins (glial fibrillary acidic protein, brain-derived neurotrophic factor), and inflammatory and coagulation markers (interleukin-1β, l-selectin, thrombospondin-1, erythrocyte, and platelet-derived microparticles). Positive findings include increases in plasma brain-derived neurotrophic factor and platelet-derived growth factor with elevated transcranial Dopplers velocities, increases in platelet-derived growth factor isoform AA with overt stroke, and increases in glial fibrillary acidic protein with acute brain injury. These promising potential neuro-biomarkers provide insight into pathophysiologic processes and clinical events, but their clinical utility is yet to be established. Additional proteomics research is needed, including broad-based proteomic discovery of plasma constituents and blood cell proteins, as well as urine and cerebrospinal fluid components, before, during and after neurological and developmental complications.

Metabolomics of AS-5 RBC supernatants following routine storage

BACKGROUND AND OBJECTIVES

The safety and efficacy of stored red blood cells (RBCs) transfusion has been long debated due to retrospective clinical evidence and laboratory results, indicating a potential correlation between increased morbidity and mortality following transfusion of RBC units stored longer than 14 days. We hypothesize that storage in Optisol additive solution-5 leads to a unique metabolomics profile in the supernatant of stored RBCs.

MATERIALS AND METHODS

Whole blood was drawn from five healthy donors, RBC units were manufactured, and prestorage leucoreduced by filtration. Samples were taken on days 1 and 42, the cells removed, and mass spectrometry-based metabolomics was performed.

RESULTS

The results confirmed the progressive impairment of RBC energy metabolism by day 42 with indirect markers of a parallel alteration of glutathione and NADPH homeostasis. Moreover, oxidized pro-inflammatory lipids accumulated by the end of storage.

CONCLUSION

The supernatants from stored RBCs may represent a burden to the transfused recipients from a metabolomics standpoint.