Altered erythrocyte membrane characteristics during anemia in childhood acute lymphoblastic leukemia

Low vitamin B12 level in relation to trace element, total sialic acid and antioxidant enzymes in children with vitamin B12 deficiency anemia

In this study, children with vitamin B₁₂ deficiency anemia (V-B₁₂DA) and control subjects were evaluated for erythrocyte glutathione peroxidase, catalase and superoxide dismutase enzyme activities, glutathione, malondialdehyde, serum total sialic acid, total antioxidant status, cobalt, chromium, copper, selenium, vanadium, zinc, iron, lead, magnesium, calcium, sodium, potassium, chloride, phosphorus levels, and the associations of these variables were assessed. The study included 50 children with V-B₁₂DA and 50 control subjects. It was found that the V-B₁₂DA group was significantly lower than the control group, with regard to the mean±the standard error of the mean levels of cobalt (0.089±0.009; 0.058±0.0063 μmol/L, p<0.01), selenium (2.19±0.087; 1.88±0.057 μmol/L, p<0.01), vanadium (1.31±0.053; 1.18±0.035 μmol/L, p<0.05), magnesium (3.02±0.15; 2.73±0.068 μmol/L, p<0.05), zinc (50.76±1.96; 42.23± 1.53 μmol/L, p<0.001), and vitamin B₁₂ (427.20±21.45; 157.08±3.96 pg/mL, p<0.001). Moreover, a significant elevation in total sialic acid (1.44±0.050; 1.61±0.043 mmol/L, p<0.01), and mean corpuscular volume (MCV) (75.37±0.95; 79.91±1.14 fL, p<0.01). It was observed that in the V-B₁₂DA, significantly linear correlations were observed between cobalt - vitamin B₁₂ (r=0.334; p=0.025), vanadium - MCV (r=0.315; p=0.017), vitamin B₁₂ - MCV (r=-0.297; p=0.026). The findings of the study indicated that the levels of cobalt, vanadium significantly associated with traditional vitamin B_12-deficiency parameters. Vitamin B₁₂ and MCV should be measured together with cobalt, vanadium for monitoring the vitamin B₁₂ deficiency anemia.

When Glycosylation Meets Blood Cells: A Glance of the Aberrant Glycosylation in Hematological Malignancies

Among neoplasia-associated epigenetic alterations, changes in cellular glycosylation have recently received attention as a key component of hematological malignancy progression. Alterations in glycosylation appear to not only directly impact cell growth and survival, but also alter the adhesion of tumor cells and their interactions with the microenvironment, facilitating cancer-induced immunomodulation and eventual metastasis. Changes in glycosylation arise from altered expression of glycosyltransferases, enzymes that catalyze the transfer of saccharide moieties to a wide range of acceptor substrates, such as proteins, lipids, and other saccharides in the endoplasmic reticulum (ER) and Golgi apparatus. Novel glycan structures in hematological malignancies represent new targets for the diagnosis and treatment of blood diseases. This review summarizes studies of the aberrant expression of glycans commonly found in hematological malignancies and their potential mechanisms and defines the specific roles of glycans as drivers or passengers in the development of hematological malignancies.

Sialic acid and biology of life: An introduction

Sialic acids are important molecule with high structural diversity. They are known to occur in higher animals such as Echinoderms, Hemichordata, Cephalochorda, and Vertebrata and also in other animals such as Platyhelminthes, Cephalopoda, and Crustaceae. Plants are known to lack sialic acid. But they are reported to occur in viruses, bacteria, protozoa, and fungi. Deaminated neuraminic acid although occurs in vertebrates and bacteria, is reported to occur in abundance in the lower vertebrates. Sialic acids are mostly located in terminal ends of glycoproteins and glycolipids, capsular and tissue polysialic acids, bacterial lipooligosaccharides/polysaccharides, and in different forms that dictate their role in biology. Sialic acid play important roles in human physiology of cell-cell interaction, communication, cell-cell signaling, carbohydrate-protein interactions, cellular aggregation, development processes, immune reactions, reproduction, and in neurobiology and human diseases in enabling the infection process by bacteria and virus, tumor growth and metastasis, microbiome biology, and pathology. It enables molecular mimicry in pathogens that allows them to escape host immune responses. Recently sialic acid has found role in therapeutics. In this chapter we have highlighted the (i) diversity of sialic acid, (ii) their occurrence in the diverse life forms, (iii) sialylation and disease, and (iv) sialic acid and therapeutics.

Oxidative Stress and Cardiovascular Complications in Chronic Kidney Disease, the Impact of Anaemia

Patients with chronic kidney disease (CKD) have significant cardiovascular morbidity and mortality as a result of risk factors such as left ventricular hypertrophy (LVH), oxidative stress, and inflammation. The presence of anaemia in CKD further increases the risk of LVH and oxidative stress, thereby magnifying the deleterious consequence in uraemic cardiomyopathy (UCM), and aggravating progression to failure and increasing the risk of sudden cardiac death. This short review highlights the specific cardio-renal oxidative stress in CKD and provides an understanding of the pathophysiology and impact of uraemic toxins, inflammation, and anaemia on oxidative stress.

Sialylation and sialyltransferase in insects

Sialic acids are negatively charged nine carbon monosaccharides located terminally on glycoproteins and glycolipids that control cellular physiological processes. Sialylation is a post translational modification (ptm) regulated by enzymes and has been studied in prokaryotes including bacteria, dueterostomes including vertebrates, Cephalochordates, Ascidians, Echinoderms and protostomes including Molluscs and Arthropods and Plant. Although diverse structures of sialylated molecules have been reported in different organisms, unravelling sialylation in insect biology is a completely new domain. Within protostomes, the study of sialylation in members of Phylum Arthropoda and Class Insecta finds importance. Reports on sialylation in some insects exist. Genetically engineered components of sialylation pathway in Spodoptera frugiperda (Sf9) cell lines have enabled our understanding of sialylation and expression of mammalian proteins in insects. In this study we have summarised the finding on (i) sialylated molecules (ii) processes and enzymes involved (iii) function of sialylation (iv) genetic engineering approaches and generation of mammalian protein expression systems (v) a comparison of sialylation machinery in insects with that of mammals (vi) genes and transcriptional regulation in insects. At present no information on structural studies of insect sialyltransferase (STs) exist. We report minor differences in ST structure in insects on complete protein sequences recorded in Genbank through in silico approaches. An indepth study of all the components of the sialylation pathway in different insect species across different families and their evolutionary significance finds importance as the future scope of this review.

Oleuropein Ameliorates Cisplatin-induced Hematological Damages Via Restraining Oxidative Stress and DNA Injury

The prevalence of cancer, in the world is increasing steadily. Despite intense research efforts, no approved therapy is yet available. Cisplatin is a chemotherapeutic drug but induces acute tissue injury. Oleuropein (OLE) is a major phenolic compound and used as a possible natural antioxidant, antimicrobial, and anticancer agent. We hypothesized that antioxidant activity of OLE may decrease cisplatin-induced oxidative stress and prevent to the development of chemotherapeutic complications including abnormality in hematological condition. Male Sprague Dawley rats were used in the experiments. Rats were randomly assigned to one of eight groups: control group; group treated with i.p. injection in a single dose of 7 mg/kg/day cisplatin; groups treated with 50, 100 and 200 mg/kg/day OLE (i.p.); and groups treated with OLE for 3 days starting at 24 h following cisplatin injection. First, hematological assessment was appreciated between control and experimental groups. Second, total oxidative stress (TOS) and total antioxidant capacity (TAC) levels of blood were measured by biochemical studies. In addition to this, oxidative DNA damage was determined by measuring as increases in 8-hydroxy-deoxyguanosine (8-OH-dG) adducts. The treatment with cisplatin elevated the TOS and 8-OH-dG levels that were then reversed by OLE. Reductions in antioxidant capacity with respect to corresponding controls were also restored by OLE treatment. These findings suggest that the OLE treatment against cisplatin-induced toxicity improves the function of blood cells and helps them to survive in the belligerent environment created by free radicals.

Sialic acids: biomarkers in endocrinal cancers

Sialylations are post translational modification of proteins and lipids that play important role in recognition, signaling, immunological response and cell-cell interaction. Improper sialylations due to altered sialyl transferases, sialidases, gene structure and expression, sialic acid metabolism however lead to diseases and thus sialic acids form an important biomarker in disease. In the endocrinal biology such improper sialylations including altered expression of sialylated moieties have been shown to be associated with disorders. Cancer still remains to be the major cause of global death and the cancer of the endocrine organs suffer from the dearth of appropriate markers for disease prediction at the early stage and monitoring. This review is aimed at evaluating the role of sialic acids as markers in endocrinal disorders with special reference to cancer of the endocrine organs. The current study is summarized under the following headings of altered sialylations in endocrinal cancer of the (i) ovary (ii) pancreas (iii) thyroid (iv) adrenal and (v) pituitary gland. Studies in expression of sialic acid in testis cancer are limited. The future scope of this review remains in the targeting of endocrinal cancer by targeting altered sialylation which is a common expression associated with endocrinal cancer.

Sialoglycosylation of RBC in visceral leishmaniasis leads to enhanced oxidative stress, calpain-induced fragmentation of spectrin and hemolysis

Visceral leishmaniasis (VL) caused by the intracellular parasite Leishmania donovani accounts for an estimated 12 million cases of human infection. It is almost always associated with anemia, which severely complicates the disease course. However, the pathological processes leading to anemia in VL have thus far not been adequately characterized to date. In studying the glycosylation patterns of peripheral blood cells we found that the red blood cells (RBC) of VL patients (RBC(VL)) express eight 9-O-acetylated sialoglycoproteins (9-O-AcSGPs) that are not detected in the RBC of healthy individuals (RBC(N)). At the same time, the patients had high titers of anti-9-O-AcSGP IgG antibodies in their sera. These two conditions appear to be linked and related to the anemic state of the patients, as exposure of RBC(VL) but not RBC(N) to anti-9-O-AcSGPs antibodies purified from patient sera triggered a series of responses. These included calcium influx via the P/Q-type but not L-type channels, activation of calpain I, proteolysis of spectrin, enhanced oxidative stress, lipid peroxidation, externalization of phosphatidyl serine with enhanced erythrophagocytosis, enhanced membrane fragility and, finally, hemolysis. Taken together, this study suggests that the enhanced hemolysis is linked to an impairment of membrane integrity in RBC(VL) which is mediated by ligand-specific interaction of surface 9-O-AcSGPs. This affords a potential explanation for the structural and functional features of RBC(VL) which are involved in the hemolysis related to the anemia which develops in VL patients.

Functions and Biosynthesis of O-Acetylated Sialic Acids

Sialic acids have a pivotal functional impact in many biological interactions such as virus attachment, cellular adhesion, regulation of proliferation, and apoptosis. A common modification of sialic acids is O-acetylation. O-Acetylated sialic acids occur in bacteria and parasites and are also receptor determinants for a number of viruses. Moreover, they have important functions in embryogenesis, development, and immunological processes. O-Acetylated sialic acids represent cancer markers, as shown for acute lymphoblastic leukemia, and they are known to play significant roles in the regulation of ganglioside-mediated apoptosis. Expression of O-acetylated sialoglycans is regulated by sialic acid-specific O-acetyltransferases and O-acetylesterases. Recent developments in the identification of the enigmatic sialic acid-specific O-acetyltransferase are discussed.

Diagnostic and Therapeutic Significance of the Oxidative Stress Parameters in Children

Pharmacotherapy of pediatric diseases represents a major challenge considering that the majority of medicines in everyday practice have not been pediatrically evaluated. The efficacy of therapy depends to a large extent on the knowledge of pathophysiological processes in the children organism at different ages. Therefore, research in that direction is of the utmost importance. An imbalance in the production of free oxygen/nitrogen species and parameters of antioxidative protection is a significant factor in many diseases (e.g. heart failure, pulmonary hypertension, asthma, neonatal sepsis, cancer etc.) in children of different age groups. Reactive oxygen/nitrogen species serve as cell signaling molecules for normal biologic processes. An increase in their generation can cause damages which can disrupt normal physiological cellular processes and eventually cause cell death. This review outlines the previous assessments of oxidative stress parameters in children of different ages for some diseases. Also, the potential diagnostic and therapeutic possibilities for the oxydative stress parameters in children have been considered.

Disease-associated glycosylated molecular variants of human C-reactive protein activate complement-mediated hemolysis of erythrocytes in tuberculosis and Indian visceral leishmaniasis

Human C-reactive protein (CRP), as a mediator of innate immunity, removed damaged cells by activating the classical complement pathway. Previous studies have successfully demonstrated that CRPs are differentially induced as glycosylated molecular variants in certain pathological conditions. Affinity-purified CRPs from two most prevalent diseases in India viz. tuberculosis (TB) and visceral leishmaniasis (VL) have differential glycosylation in their sugar composition and linkages. As anemia is a common manifestation in TB and VL, we assessed the contributory role of glycosylated CRPs to influence hemolysis via CRP-complement-pathway as compared to healthy control subjects. Accordingly, the specific binding of glycosylated CRPs with erythrocytes was established by flow-cytometry and ELISA. Significantly, deglycosylated CRPs showed a 7-8-fold reduced binding with erythrocytes confirming the role of glycosylated moieties. Scatchard analysis revealed striking differences in the apparent binding constants (10(4)-10(5) M(-1)) and number of binding sites (10(6)-10(7)sites/erythrocyte) for CRP on patients' erythrocytes as compared to normal. Western blotting along with immunoprecipitation analysis revealed the presence of distinct molecular determinants on TB and VL erythrocytes specific to disease-associated CRP. Increased fragility, hydrophobicity and decreased rigidity of diseased-erythrocytes upon binding with glycosylated CRP suggested membrane damage. Finally, the erythrocyte-CRP binding was shown to activate the CRP-complement-cascade causing hemolysis, even at physiological concentration of CRP (10 microg/ml). Thus, it may be postulated that CRP have a protective role towards the clearance of damaged-erythrocytes in these two diseases.

Genome-wide association study of childhood acute lymphoblastic leukemia in Korea

We conducted a genome-wide association study of childhood acute lymphoblastic leukemia (ALL) in a case-control study conducted in Korea. Incident childhood ALL cases (n=50) and non-cancer controls (n=50) frequency-matched to cases by age and sex, recruited from three teaching hospitals in Seoul between 2003 and 2008, were genotyped using Affymetrix SNP Array 6.0 platform. ALL risks were estimated as odds ratios (ORs) and 95% confidence intervals (CIs) adjusted for age and birth weight. The false discovery rate (FDR) was used for adjusting multiple tests. Of these 1 million SNPs, six SNPs in 4 genes (HAO1 rs6140264, EPB41L2 rs9388856, rs9388857, rs1360756, C2orf3 12105972, MAN2A1 rs3776932) were strongly associated with childhood ALL risk (P(dominant)<or=0.0001 and P(trend)<0.006). These SNPs remained significant after FDR adjustment (FDR value <0.2). Our genome-wide association study in Korea children identified a few genetic variations as potential susceptibility markers for ALL, warranting further replication studies among various ethnic groups.

Measurements of oxidative stress status and antioxidant activity in chronic leukaemia patients

There is an interactive relationship between leukaemia and oxidative stress. Leukaemic cells produce larger amounts of reactive oxygen species (ROS) than non-leukaemic cells as they are under a continual state of oxidative siege. So, this study was performed on 20 patients with chronic leukaemia from the Oncology Centre, Mansoura University. We measured leucocytic H2O2 concentrations and lipid peroxidation as serum malondialdehyde (MDA) concentration, serum total antioxidant activity, plasma ascorbic acid and dehydroascorbic acid concentrations, blood reduced glutathione concentration, haemolysate G6PD activity, blood catalase activity, serum superoxide dismutase (SOD) activity and serum anti-dsDNA concentration. We found that chronic leukaemia patients showed a significant increase (P &lt; 0.05) in leucocytic H2O2, serum MDA concentration and total anti-oxidant activity either before or after treatment as compared with control group. Also, there was a significant increase in the other parameters (glutathione, catalase and SOD) either before or after treatment, but we found a significant decrease in ascorbic acid concentration and G6PD activity. There was a significant increase in anti-dsDNA concentration either before or after treatment. It can be concluded that leukaemic patients produce larger amounts of ROS than non-leukaemic patients. Also, the increase in antioxidant activity in leukaemic patients is not high enough to counteract the harmful effects of free radicals. This scenario becomes worse after administration of chemotherapy.

Down regulation of membrane-bound Neu3 constitutes a new potential marker for childhood acute lymphoblastic leukemia and induces apoptosis suppression of neoplastic cells

Membrane-linked sialidase Neu3 is a key enzyme for the extralysosomal catabolism of gangliosides. In this respect, it regulates pivotal cell surface events, including trans-membrane signaling, and plays an essential role in carcinogenesis. In this report, we demonstrated that acute lymphoblastic leukemia (ALL), lymphoblasts (primary cells from patients and cell lines) are characterized by a marked down-regulation of Neu3 in terms of both gene expression (-30 to 40%) and enzymatic activity toward ganglioside GD1a (-25.6 to 30.6%), when compared with cells from healthy controls. Induced overexpression of Neu3 in the ALL-cell line, MOLT-4, led to a significant increase of ceramide (+66%) and to a parallel decrease of lactosylceramide (-55%). These events strongly guided lymphoblasts to apoptosis, as we assessed by the decrease in Bcl2/Bax ratio, the accumulation of Neu3 transfected cells in the sub G0-G1 phase of the cell cycle, the enhanced annexin-V positivity, the higher cleavage of procaspase-3. Therefore, the reduced expression of Neu3 in ALL could help lymphoblasts to survive, maintaining the cellular content of ceramide below a critical level. Interestingly, we found that Neu3 activity varied in relation to disease progression, increasing in clinical remission after chemotherapy, and decreasing again in patients that relapsed. In addition, a negative correlation was observed between Neu3 expression and the percentage of the ALL marker 9-OAcGD3 positive cells. Consequently, Neu3 could represent a new potent biomarker in childhood ALL, to assess the efficacy of therapeutic protocols and to rapidly identify an eventual relapse.

O-acetylated sialic acids: multifaceted role in childhood acute lymphoblastic leukaemia

Childhood acute lymphoblastic leukaemia (ALL), a malignant transformation of the lymphoblasts, is highly responsive to chemotherapy. However, due to certain inadequacy in detection of minimal residual disease (MRD), relapse is a common phenomenon. To address this question, the present review deals with the induction of an unique O-acetyl derivative of sialic acid on a few disease-associated glycoproteins and glycolipids at the onset of childhood ALL, a finding of our group in the last decade. This information has been successfully utilized for diagnosis and prognosis of the disease. Existing literature is included for comparison. Additionally, cell surface overexpression of 9-O-acetylated sialoglycoproteins and antibodies against them present in patients' sera aid the survival of the malignant lymphoblasts and suggest a multifaceted role played by these molecules. Taken together, monitoring these molecules helps not only in unravelling the biology of this paediatric malignancy but also in personalizing the treatment strategies for the betterment of the patient population.

O-acetylation of sialic acids is required for the survival of lymphoblasts in childhood acute lymphoblastic leukemia (ALL)

Exploiting the selective affinity of Achatinin-H towards 9-O-acetylneuraminic acid(alpha2-6)GalNAc, we have demonstrated the presence of 9-O-acetylated sialoglycoproteins (Neu5,9Ac(2)-GPs) on hematopoietic cells of children suffering from acute lymphoblastic leukemia (ALL), indicative of defective sialylation associated with this disease. The carbohydrate epitope of Neu5,9Ac(2)-GPs(ALL) was confirmed by using several synthetic sialic acid analogues. They are functionally active signaling molecules as demonstrated by their role in mediating lymphoproliferative responses and consequential increased production of IFN-gamma due to specific stimulation of Neu5,9Ac(2)-GPs on PBMC(ALL) with Achatinin-H. Cells devoid of 9-O-acetylations (9-O-AcSA(-)) revealed decreased nitric oxide production as compared to 9-O-AcSA(+) cells on exposure to IFN-gamma. Under this condition, a decrease in viability of 9-O-AcSA(-) cells as compared to 9-O-AcSA(+) cells was also observed which was reflected from increased caspase 3 activity and apoptosis suggesting the protective role of this glycotope. These Neu5,9Ac(2)-GPs are also capable of inducing disease-specific anti-Neu5,9Ac(2)-GPs antibodies in ALL children. Additionally, we have observed that disease-specific anti-Neu5,9Ac(2)-GPs have altered glycosylation profile, and they are incapable of exerting a few Fc-glycosylation-sensitive effector functions. These observations hint toward a disbalanced homeostasis, thereby enabling the cancer cells to escape host defense. Taken together, it may be hypothesized that Neu5,9Ac(2)-GPs and their antibodies play a prominent role in promoting the survival of lymphoblasts in ALL.

Role of C-reactive protein in complement-mediated hemolysis in Malaria

Human C-reactive protein (CRP) is a clinically important classical acute phase protein. Although CRP has been reported to bind with many nucleated cells, the direct binding of CRP to erythrocytes in diseases remains largely unexplored. The main focus of the present study was to investigate the binding of disease-specific CRP to erythrocytes of same patients. Distinct molecular variant of disease-specific CRP was affinity purified from sera of malaria patients (CRP(Mal)). This CRP showed strong binding with malaria erythrocytes (RBC(Mal)) as confirmed by flow cytometric analysis (FACS), enzyme-linked immunosorbent assays (ELISA), and radio binding assays. Calcium and phosphoryl choline (PC) were found to be essential for this interaction. A 2.3-fold increased binding of induced CRP to RBC(Mal) as compared to normal erythrocytes (RBC(N)) confirmed disease-specificity. Preincubation of RBC(Mal) with unconjugated CRP showed 3-5 fold inhibition. The association constant of CRP and RBC(Mal) was 4.7 x 10(6) cpm/microg with the corresponding number of receptors/cell being 4.3 x 10(5). The effector function of CRP(Mal) has been demonstrated by its potency to activate the complement pathway. An optimal dose of 10 microg/ml of CRP induced three-fold higher hemolysis of patient erythrocytes as compared to RBC(N). These studies provide direct evidence for an important phagocytic functional interaction of this acute-phase protein by triggering the CRP-complement pathway after the binding of CRP(Mal) with RBC(Mal). Hemolysis as triggered by this pathway may be one of the causative factors of anemia, a common clinical manifestation of this disease.

Red cell morphology in leukemia, hypoplastic anemia and myelodysplastic syndrome

Leukemic patients of different classifications are associated with anemia. Such clinical conditions are often referred to as refractory anemia, paraoxymal nocturnal hemoglobinuria, hemolytic uremia and autoimmune hemolytic anemia, all of which could be categorized as the cancer cachexia. In the present work, we have studied the overall morphology of intact red cells in different leukemic patients along with patients of hypoplastic anemia (HPA) by scanning electron microscopy. We have also studied the ultrastructure of the red cell surface membranes by transmission electron microscopy. For all experiments, erythrocytes from normal individuals served as controls. We have shown direct evidence of the altered red cell (RBC) membrane morphology irrespective of the hemoglobin status of the patients which includes (1) presence of large central holes in RBCs of acute myeloid leukemia (AML), (2) presence of thorn- and horn-like structure in RBCs of acute lymphoblastic leukemia (ALL) and chronic myeloid leukemia (CML) and (3) flaccid appearance of RBCs in chronic lymphocytic leukemia (CLL) patients. A mixture of the above mentioned structures were found in the red cells of patients suffering from myelodysplastic syndrome (MDS) and in case of patients of HPA the RBCs lost the normal biconcave structures. TEM studies revealed presence of pores with diameters ranging from 100 to 200nm on the RBC membrane surface of myeloid leukemia with AML being the most prominent among others. Such pathophysiological alterations of the RBC morphology in leukemic patients could be identified as characteristic signature of the onset of anemia associated with the disease.