Littérature scientifique sur le sujet « Stomatocytosi »

Abstract Introduction Stomatocytes in peripheral blood are pathognomonic findings in multiple conditions along with hemolysis and reticulocytosis, often suggestive of erythrocyte membrane transport defects. These uncommon disorders are usually difficult to diagnose due to a wide range of overlapping phenotypes and a perception of stomatocytes being artefacts. Genes involved in these disorders are multiple (RHAG,SLC4A1, ABCG5, ABCG8, PIEZO1,KCNN4, ABCB6, SLC2A1 etc) rendering Sanger sequencing costly and labor intensive. Phenotypes vary from transfusion-dependent anemia to compensated hemolysis. Methods Seventeen patients were encountered in 12 families and enrolled in this study. Majority of the cases showed the presence of significant numbers of red blood cells showing stomatocytes with or without thrombocytopenia. Various hematological, biochemical and molecular tests were used to exclude thalassemia syndromes and hemoglobinopathies, glucose-6-phosphate dehydrogenase (G6PD) deficiency, autoimmune hemolytic anemia, hereditary spherocytosis (HS) and pyruvate kinase deficiency. Genomic DNA was extracted by the QIAamp DNA Blood Midi Kit and quantified on NanoDrop 2000 spectrophotometer and QubitFluorometer. DNA libraries were prepared using Illumina's custom panels (TruSight One Sequencing Panel and TruSeq Custom Amplicon v1.5) and sequenced on a MiSeq Sequencing System. MiSeq Reporter and VariantStudio were used for analysis, classification, and reporting of variants. Variants which were predicted pathogenic by in silico analysis using PolyPhen-2, SIFT, PROVEAN (http://provean.jcvi.org/), Mutpred (http://mutpred.mutdb.org/) and Human Splicing Finder as indicated, were subjected to Sanger sequencing in the patient and family members (where available). Results Of these 17 patients, 10 patients in 6 families were diagnosed to have Mediterranean stomatocytosis/ macrothrombocytopenia. All had the presence of stomatocytes along with macrothrombocytopenia, short stature, continuous abdominal discomfort and marked pleiotropic effects in different cases. This is a syndromic form of stomatocytosis and defects in ABCG5/ABCG8 genes were found and showed an autosomal recessive inheritance pattern. One case did not show any mutation. This number of cases suggests that this disorder is not rare in India and is probably underdiagnosed as patients have mild or moderate anemia and are often misdiagnosed as cases with HS. One of the patients also had coinheritance of G6PD deficiency (G6PD Kerela Kalyan). Patients with Mediterranean stomatocytosis/macrothrombocytopenia are advised to take sterol-absorption inhibitor 'ezetimibe' to reduce sterol accumulation. We also found 2 unrelated patients with stomatocytosis, reticulocytosis and splenomegaly with overhydrated hereditary stomatocytosis (OHSt) and pathogenic mutation in RHAG gene was found in both of them. The pattern of inheritance is sporadic or autosomal dominant. Splenectomy was deferred in a patient with OHSt as postsplenectomy thrombotic complications are known to occur and is contraindicated. Four patients in 3 families were found to have mutations in PIEZO1 gene which translates to red cell membrane mechanosensitive cation channel protein, causing xerocytosis/dehydrated hereditary stomatocytosis and 3 patients had severe anemia and were transfusion dependent. One patient showed the presence of stomatocytes and macrothrombocytopenia was found to have probably disease causing variant in SLC2A1 gene. She was incidentally undergoing treatment for infertility when the stomatocytosis was noted. Conclusions Stomatocytic disorders appear to be underdiagnosed in India which is compounded by the protean clinical manifestations, milder phenotypes, low index of suspicion and non-availability of molecular confirmation. Astute phenotype characterization is critical as it will help in establishing the causality of the variants identified and appropriate genetic counseling. Recently NGS for hemolytic anemias has led to rapid molecular characterization and accurate phenotypic correlation. Disclosures No relevant conflicts of interest to declare.

Abstract Metabolic crenation of red cells is reversible; on addition of nutrients, echinocytes recover the normal discoid shape. When the shape recovery takes place in the presence of reducing agents such as dithiothreitol (DTT), morphological change continues until the cells are stomatocytic. The degree of stomatocytosis varies, depending on the cell morphology when the nutrients and reducing agent are added. DTT has minimal effect on the shape of normal discocytes, but in its presence, mildly echinocytic cells become slightly cupped and advanced- stage echinocytes become severely stomatocytic. DTT must be present continuously for development and retention of stomatocytosis; echinocytes preincubated with or metabolically depleted in DTT do not become stomatocytic when supplemented in the absence of DTT, and DTT- induced stomatocytes revert to discocytes when the reducing agent is removed. DTT has no effect on adenosine triphosphate synthesis or equilibrium cell glutathione levels, and the induced stomatocytosis is not inhibited by excluding oxygen from cells during depletion. Spectrin phosphorylation and phosphate turnover are not affected by DTT. The echinocyte-to-discocyte transformation coincides with phosphorylation of membrane inner monolayer lipids (diacylglycerol to phosphatidic acid and phosphatidylinositol to phosphatidylinositol-4,5-bisphosphate). Overphosphorylation of these phospholipids is not responsible for the exaggerated shape recovery seen with reducing agents; phosphorylation of inner monolayer lipids proceeds identically in the presence and absence of DTT.

Metabolic crenation of red cells is reversible; on addition of nutrients, echinocytes recover the normal discoid shape. When the shape recovery takes place in the presence of reducing agents such as dithiothreitol (DTT), morphological change continues until the cells are stomatocytic. The degree of stomatocytosis varies, depending on the cell morphology when the nutrients and reducing agent are added. DTT has minimal effect on the shape of normal discocytes, but in its presence, mildly echinocytic cells become slightly cupped and advanced- stage echinocytes become severely stomatocytic. DTT must be present continuously for development and retention of stomatocytosis; echinocytes preincubated with or metabolically depleted in DTT do not become stomatocytic when supplemented in the absence of DTT, and DTT- induced stomatocytes revert to discocytes when the reducing agent is removed. DTT has no effect on adenosine triphosphate synthesis or equilibrium cell glutathione levels, and the induced stomatocytosis is not inhibited by excluding oxygen from cells during depletion. Spectrin phosphorylation and phosphate turnover are not affected by DTT. The echinocyte-to-discocyte transformation coincides with phosphorylation of membrane inner monolayer lipids (diacylglycerol to phosphatidic acid and phosphatidylinositol to phosphatidylinositol-4,5-bisphosphate). Overphosphorylation of these phospholipids is not responsible for the exaggerated shape recovery seen with reducing agents; phosphorylation of inner monolayer lipids proceeds identically in the presence and absence of DTT.

Abstract The hereditary stomatocytoses are a series of dominantly inherited hemolytic anemias in which the permeability of the erythrocyte membrane to monovalent cations is pathologically increased. The causative mutations for some forms of hereditary stomatocytosis have been found in the transporter protein genes, RHAG and SLC4A1. Glucose transporter 1 (glut1) deficiency syndromes (glut1DSs) result from mutations in SLC2A1, encoding glut1. Glut1 is the main glucose transporter in the mammalian blood-brain barrier, and glut1DSs are manifested by an array of neurologic symptoms. We have previously reported 2 cases of stomatin-deficient cryohydrocytosis (sdCHC), a rare form of stomatocytosis associated with a cold-induced cation leak, hemolytic anemia, and hepatosplenomegaly but also with cataracts, seizures, mental retardation, and movement disorder. We now show that sdCHC is associated with mutations in SLC2A1 that cause both loss of glucose transport and a cation leak, as shown by expression studies in Xenopus oocytes. On the basis of a 3-dimensional model of glut1, we propose potential mechanisms underlying the phenotypes of the 2 mutations found. We investigated the loss of stomatin during erythropoiesis and find this occurs during reticulocyte maturation and involves endocytosis. The molecular basis of the glut1DS, paroxysmal exercise-induced dyskinesia, and sdCHC phenotypes are compared and discussed.

Abstract Stomatocytosis is an inherited autosomal dominant hemolytic anemia and includes overhydrated hereditary stomatocytosis (OHS), dehydrated hereditary stomatocytosis (DHS), hereditary cryohydrocytosis (CHC) and familial pseudohyperkalemia (FP). Here, we report a novel variant of hereditary stomatocytosis due to a de-novo band 3 mutation due to G>A transition at nucleotide 2500 in exon 17 (p. G796R, band3CEINGE) associated with dyserythropoietic phenotype. This 43-years-old Caucasian female (II-2) with unrelated parents was admitted to our hospital for mild anemia evaluation. The patient was in good health until 7 years when she frequently experienced asthenia. Anemia was first recognized at the age of eighth years with presence of jaundice and hyperchromic urine, but she had never received blood transfusions. We observed a mild hypochromic macrocytic anemia with a hemoglobin level of 11.5 g/dL, a mean cell volume (MCV) of 110 fL, and a mean hemoglobin concentration (MCH) of 36.1 pg, the reticulocyte count was 64 × 103/μL. There was a typical hemolytic features: high levels of indirect bilirubin (3.48 mg/dL) and lactate dehydrogenase ( 567 U/l, v.n. 240– 480 U/l ) with negativity at direct and indirect Coomb’s test. Spleen was enlarged and ultrasonography detected 15 cm of longitudinal size. She was cholecystectomized at the age of 14 years because of numerous symptomatic small stones. Serum iron, soluble transferrin receptor, serum ferritin and transferrin saturation levels were all increased, while the transferrin was in the normal range.Other blood tests including osmotic fragility with incubated and fresh erythrocytes, serum electrolytes, B12 and folate levels, erythrocyte enzyme levels, EMA test and Pink test were normal. Peripheral blood smear showed anisopoikilocytosis with rare stomatocytes and no spherocytes. Bone marrow aspirate showed remarkable dyserythropoiesis with increased number of erythroblasts and binucleate erythroblasts, basophilic erythroblasts with alterations, irregular nuclei maturation, intererythroblastic bridges and erythroblasts with basophilic stippling. She received since the age of 14 yrs a diagnosis for congenital dyserythropoietic anemia type I. Patients red cells showed increase Na+ content and decrease K+ content; reduced Na-K pump activity and increased Na-H exchange, NKCC cotransport and KCC cotransport activities. We then functionally characterized band 3 CEINGE in Xenopus oocytes, showing that the mutated band 3 is converted from anion exchanger (Cl−, HCO3 −) function to unregulated cation pathway for Na+ and K+. The mutated band 3 was also associated with increased tyrosine phosphorylation pattern of some red cell membrane proteins. During erythropoiesis band 3 protein is the last cytoskeletal protein to appear, thus the dyserythropoietic phenotype may be related to a possible role of the mutated band 3 in perturbation of cytoskeleton assembly in the late stage of erythropoiesis, allowing us to conclude for a new variant of stomatocytosis with dyserythropoietic phenotype.

Abstract We describe a case of chronic hemolytic anemia due to the co-presence of pyruvate kinase (PK) deficiency and Hereditary Stomatocytosis (HSto). The propositus was a 30 years old adopted male with no known family history; he had severe neonatal jaundice requiring exchange transfusion, followed by a life-long history of moderate to severe chronic hemolytic anemia (Hb 7–10 g/dL), with jaundice and splenomegaly. At the age of 6 months hemoglobin screening was made and a beta trait was found. At the age of 20 splenectomy and cholecystectomy were performed. Surgery resulted in an increase of 1.5 g/dL in haemoglobin, and in a conspicuous rise of reticulocytes (from 125×109/L to 562×109/L). Two thrombotic events occurred thereafter, the former 6 days after surgery, and the latter two years later, during a toxoplasmosis infection. At the time of the study Hb was 10.8 g/dL, MCV 82.2 fL, reticulocytes 562×109/L, unconjugated bilirubin 2.19 mg/dL, LDH 335 U/L, haptoglobin <20 mg/dL, serum ferritin 342 ng/mL and transferrin saturation 71%. The peripheral blood smear examination showed the presence of echinocytes (13%), stomatocytes (11%), acantocytes (10%), schistocytes (7%), elliptocytes (6%), spherocytes (4%), target cells (4%) and a few erythroblasts. Erythrocyte osmotic fragility was decreased; screening test for unstable hemoglobins and sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) of red cell membrane gave normal results. The study of the most important red cell enzymes revealed reduced PK activity (6.0 UI/gHb, normal range 11.1–15.59 UI/gHb) and thermal stability (43%, normal range 57–100%). Direct sequencing of PK-LR gene showed a compound heterozygosity for mutation 1456T (Arg486Trp) and the new variant −73g>c. Mutation −73g>c occurs in the most proximal of the four GATA motifs in the R-type promoter region and possibly result in a decrease of mRNA synthesis, as already reported for the variant −72a>g (Manco et al, 2000). Molecular analysis of HFE gene showed heterozygosity for H63D mutation. The history of post splenectomy thrombosis and the presence of stomatocytes in peripheral blood smear prompted us to investigate for the coexistence of hereditary stomatocytosis. The determination of plasma potassium and sodium concentration revealed an increase in intracellular sodium (16.3 mmol/LRBC, reference range 5.0–12.0) and a decrease in intracellular potassium (74.73 mmol/LRBC, reference range 90–103), suggestive for a diagnosis of dehydrated HSto, or hereditary xerocytosis. This defect likely accounts for the thrombophilic state in this case, since HSto is known to be associated with hypercoagulability, particulary after splenectomy.

Abstract Erythrocytes must have the capacity to undergo marked membrane deformation and shape changes in order to circulate through capillaries and respond to a range of shear stresses. To study the interrelationships between membrane deformability and the capacity for shape transformation, we created rigid membranes using several agents and then examined the ability of these erythrocytes with rigid membranes to undergo amphipath-induced shape change. We have previously shown that wheat germ agglutinin (WGA) and a monoclonal antibody to glycophorin A (R-10) cause membrane rigidity as measured by ektacytometry. Experiments were therefore designed to produced comparably rigid membranes using WGA, R-10, and diamide, and then to test the ability of lysophosphatidylcholine to produce echinocytes, and primaquine to produce stomatocytes. We found that diamide treatment substantially blocked both types of shape change. In contrast, R-10 binding did not impair either primaquine- or lysophosphatidylcholine- induce shape change. Further, WGA blocked echinocyte transformation, as previously reported, but not stomatocytosis. Using reduced and unreduced gel electrophoresis and Triton extraction, we compared the biochemical changes associated with WGA-, diamide-, and R-10-induced rigidity, and found them to be different. We conclude that not all rigid cells are incapable of shape change, and therefore that decreased membrane deformability is not predictive of impaired capacity for shape change.

Erythrocytes must have the capacity to undergo marked membrane deformation and shape changes in order to circulate through capillaries and respond to a range of shear stresses. To study the interrelationships between membrane deformability and the capacity for shape transformation, we created rigid membranes using several agents and then examined the ability of these erythrocytes with rigid membranes to undergo amphipath-induced shape change. We have previously shown that wheat germ agglutinin (WGA) and a monoclonal antibody to glycophorin A (R-10) cause membrane rigidity as measured by ektacytometry. Experiments were therefore designed to produced comparably rigid membranes using WGA, R-10, and diamide, and then to test the ability of lysophosphatidylcholine to produce echinocytes, and primaquine to produce stomatocytes. We found that diamide treatment substantially blocked both types of shape change. In contrast, R-10 binding did not impair either primaquine- or lysophosphatidylcholine- induce shape change. Further, WGA blocked echinocyte transformation, as previously reported, but not stomatocytosis. Using reduced and unreduced gel electrophoresis and Triton extraction, we compared the biochemical changes associated with WGA-, diamide-, and R-10-induced rigidity, and found them to be different. We conclude that not all rigid cells are incapable of shape change, and therefore that decreased membrane deformability is not predictive of impaired capacity for shape change.

Abstract Abstract 3170 BACKGROUND: The hereditary stomatocytoses are a rare, diverse group of clinical conditions associated with chronic red blood cell hemolysis and increased erythrocyte membrane permeability to monovalent cations. The most common form of hereditary stomatocytosis is dehydrated stomatocytosis (DHSt, also called hereditary xerocytosis) first reported by Miller et al. (Blood 38:184, 1971). We studied two genetically unrelated kindreds with DHSt, one from Western Canada and the other, the original DHSt kindred reported by Miller et al., from upstate New York. Although the DHSt causative gene is unknown, previous studies have mapped the DHSt locus to 16q23 – 16qter. OBJECTIVES: To define the chromosomal region carrying the disease locus in these two families using DNA linkage analysis. METHODS: PCR-based genotyping was performed on genomic DNA according to standard methods. Fine mapping was performed using markers on the telomeric end of chromosome 16. Linkage data was generated from both paternal and maternal meioses. LOD scores (logarithm (base 10) of odds) were determined at assumed recombination fractions (theta) 0.00, 0.05, 0.10, 0.20, 0.30 and 0.40. Continuous allelic alignments were manually generated. RESULTS: Based on reticulocyte count, MCHC, and osmotic fragility, disease phenotypes were identified in 29 individuals of the Canadian kindred, and 27 individuals of the New York kindred. Linkage data from both families confirmed that the disease-causing locus mapped to chromosome 16. In the Canadian kindred, significant LOD scores (> +3.00) were established between the disease-causing locus (DHSt) and D16S3074, D16S2621 and D16S3026. Three recombinants were observed between DHSt:D16S3074, two between DHSt:D16S2621 and none between DHSt:D16S3026. Significant LOD scores were also established between DHSt and D16S3074, D16S476, and D16S413 in the New York kindred, and recombination between DHSt:D16S3074 was also observed. Definition of critical recombination events allowed us to define the centromeric boundary of the region containing the disease-causing locus as D16S2621, a 2.4 cM region containing 51 known or predicted genes. CONCLUSIONS: Genetic linkage analysis has confirmed DHSt linkage to chromosome 16 in two unrelated kindreds and has refined the assignment of DHSt to chromosome 16q24.2 – 16qter. Disclosures: No relevant conflicts of interest to declare.

L’identification des gènes de maladies Mendeliennes été rendue possible dans les années 1980. Le séquençage du génome humain dans les années 2000, et l’arrivée du séquençage haut débit dans les années 2010 ont permis une progression phénoménale du rythme de ces découvertes génétiques. Cependant, ces techniques ont permis d’élucider les maladies les plus accessibles, de par leur homogénéité génétique, leur forte pénétrance pour les maladies dominantes, et leur prévalence élevée. Aujourd’hui, la communauté génétique se heurte à des difficultés de plus en plus nombreuses pour identifier les maladies non monogéniques, hétérogènes, ou très rares : recruter des familles porteuses d’une maladie très rare et cliniquement bien caractérisée, ou de grandes cohortes de patients atteints de maladies communes à composante génétique, nécessite un effort clinique, logistique et financier important. De plus, le séquençage d’exome pris isolément ne permet généralement pas l’élucidation de ces pathologies. Cet outil bien que puissant trouve ses limites dans les modèles génétiques sus-cités. La réussite des approches récentes vient de son utilisation en association avec d’autres techniques, adaptées aux caractéristiques des maladies comme la rareté, la dimension polygénique, ou l’hétérogénéité génétique. J’ai utilisé le séquençage d’exome dans l’identification de gènes de maladies cardiovasculaires rares, par trois stratégies combinées différentes. La première pathologie appelée stomatocytose héréditaire, est rare, relativement homogène mais présente des difficultés de phénotypage. Elle a été caractérisée par séquençage d’exome en association avec une analyse de liaison traditionnelle et l’identification d’une endophénotype fiable. Cette approche a été appliquée avec succès dans ce modèle relativement peu complexe de maladie. La seconde pathologie étudiée, l’anévrysme de l’aorte abdominale (AAA), est une maladie commune à forte composante héréditaire, avec de rares formes dominantes à pénétrance élevée. J’ai associé séquençage d’exome en modèle dominant et recherche de variants rares dans une cohorte de cas sporadiques afin d’identifier un gène de susceptibilité à la pathologie. Cette approche s’est révélée plus complexe à mettre en place, et son efficacité peut être discutée dans le cas d'une étude d'association centrée sur un gène candidat. Enfin, la troisième partie de ce travail est consacrée à la dysplasie fibromusculaire (DFM), maladie très hétérogène sur le plan génétique, peu pénétrante, et d’endophénotype peu accessible. J’ai appliqué dans cette troisième étape le séquençage d’exome à plus grande échelle (30 individus), en association à des stratégies de filtres sophistiqués exploitant tous les types de transmission Mendélienne. J'y ai aussi associé l'utilisation des outils bioinformatiques et bases de données biologiques accessibles à la communauté scientifique. Les résultats obtenus par cette dernière approche sont prometteurs, probablement du fait des caractéristiques inhérentes de cette pathologie. L’utilisation de ces trois stratégies très différentes, adaptées aux contraintes de chaque pathologie, permet d’évaluer la puissance et l’efficacité des approches combinées utilisant le séquençage d’exome. Leurs difficultés inhérentes, leur inadaptation à certaines situations génétiques, ainsi que les pistes d’amélioration nécessaires pour l’élucidation des maladies génétiques de cause inconnue sont aussi abordés
Identifying genes of Mendelian disorders has started within the eighties. The pace of new genes discovery has been dramatically accelerated by the availability of the human genome sequence in the 2000s, and the next-generation sequencing technologies in the 2010s. However, a majority of the elucidated conditions so far correspond to relatively simplified situations, where the prevalence and the penetrance of the condition are high and the genetic heterogeneity is low. Nowadays, geneticists meet more and more situations where gene identification in unknown disorders can be tricky. Heritable conditions that are very rare, heterogenous or with imperfect Mendelian transmission can only be elucidated using large cohorts of patients, with a very well-characterized phenotype. This requires clinical, financial and logistical efforts to be made by the research teams. Generally, using exome sequencing alone is not efficient enough to elucidate these types of conditions. The power of recently developed strategies comes from its association with other genetic analysis tools, that have been specifically developed in the context of rare, heterogenous, or polygenic disorders. I employed exome sequencing in the identification of cardiovascular genetic conditions, using three different strategies. In the first condition, called hereditary xerocytosis, using linkage analysis together with exome sequencing of distant relatives was successful in identifying the causative gene. This was made possible by the identification of a reliable endophenotype, and the relative genetic homogeneity of the disorder. The second condition I studied is the abdominal aortic aneurysm (AAA), a common disorder with a strong hereditary component and rare situations of fully penetrant, dominant inheritance. I combined exome sequencing in a family with dominant inheritance with rare variants analysis of the candidate gene in a large cohort of sporadic AAA. This analysis is more complex and can be hazardous in the context of a candidate gene approach. The third strategy was developed for the study of fibromuscular dysplasia (FMD) which is a very heterogenous condition with low penetrance and no specific endophenotype. I combined exome sequencing in a group of 30 cases and relatives with filtering strategies for any type of Mendelian inheritance. I also used available bioinformatics tools and databases for refining the candidate genes filtering. This strategy provided promising results, probably due to the genetic characteristics of this condition. In each of these examples, I adapted the analysis strategy to the peculiarities of the disorder. The results presented here enable to evaluate the efficiency of combined approaches using exome sequencing. Their specificities, limits, and the optimization that need to be done to elucidate the remaining unsolved genetic conditions are discussed

La stomatocitosi ereditaria (HSt) rappresenta un gruppo di anemie emolitiche molto rare con ereditarietà per lo più dominante, dovuta a perdita di ioni monovalenti (Na+ e K+) attraverso la membrana. Questa forma di anemia emolitica è clinicamente eterogenea e comprende la stomatocitosi ereditaria con emazie iperidratate (Overhydratated Hereditary Stomatocytosis), la stomatocitosi ereditaria con emazie disidratare (Dehydrated Hereditary Stomatocytosis), la pseudoipercaliemia familiare (Familial Pseudohyperkalaemia FP) e la crioidrocitosi ereditaria (Hereditary Cryohydrocytosis CHC). Lo scopo del nostro progetto è quello di valutare differenze nell’espressione delle proteine di membrana eritrocitaria di 5 pazienti affetti da DHSt (appartenenti a 2 famiglie diverse) provenienti dal sud Italia quando confrontati con 10 soggetti sani tramite 2D-DIGE. Attraverso questo approccio abbiamo ottenuto 1000 spots ed in seguito ad un’accurata analisi statistica nella quale abbiamo isolato tutti gli spots con un p-value inferiore a 0.075 (Student’s paired t test) e un AV.RATIO compreso tra +1,35 e -1.35, abbiamo focalizzato la nostra attenzione su 65 spots ritenuti significativi (36 risultano maggiormente espressi nei pazienti mentre 29 risultano meno espressi). Di questi spots è stato possibile isolare su gel bidimensionale solo 51 spots dei quali 33 risultano maggiormente espressi nei pazienti e 18 meno espressi. L'analisi dei peptidi estratti da ciascuno spot è stata effettuata mediante analisi LC/MS/MS che è riuscita ad identificare 24 proteine differenzialmente espresse ma solo le seguenti proteine sono risultati interessanti ai fini del nostro studio: Peptide C-Band3, Flotillina 1 and 2, Stomatina, perossiredoxina 1 e 2, Catalase, Annexina A1, Citovillina 2, RAP2B e RAP1A che risultano più espresse nei pazienti; Gliceraldeide-3-fosfatodeidroganasi, Aldolase A, proteina G subunità beta che risultano meno espresse. Questi risultati, ed in particolare l’aumento delle perossiredoxine e della catalase A1 suggeriscono che nei pazienti affetti da DHSt vi è un maggiore stress ossidativo, incentivato anche dalla diminuzione di alcuni enzimi della glicolisi importanti per la produzione di NADH e quindi di potenziali riducenti. Un altro dato importante è l’aumento della proteolisi della porzione N-terminale della Banda3 e l’aumento di proteine coinvolte nella formazione di zattere lipidiche (Flotillina 1 and 2, Stomatina e Citovillina 2), nell’adesione cellulare (Annexina A1) e nella vescicolazione (RAP1A e RAP2B). Attualmente sono in corso studi per valutare se vi è un incremento della fosforilazione della banda 3 e un aumento della vescicolazione.
Hereditary stomatocytosis (HSt) describes a wide spectrum of autosomal dominantly inherited disorders in which the basal red cell membrane cation permeability is increased. The cation leak results in the regulations of cellular volume, which can lead to morphological abnormality. Clinically HSt is very heterogeneous and we can identify four principal form: Overhydrated Hereditary Stomatocytosis (OHSt), Dehydrated Hereditary Stomatocytosis (DHSt), Familial Pseudohyperkalemia (FP) and Hereditary Cryohydrocytosis (CHC). Since, the DHSt pathogenesis is linked to a defect or a decreased in a membrane protein, we studied the red blood cells membrane proteome by 2D-DIGE. In fact we selected 2 DHSt family, for a total of 5 patients to isolate the membrane proteins and compare they with membrane proteins of 10 healthy controls. Approximately, 1000 protein spots were detected, the protein spots were then filtered for the statistically relevant trend of regulation: p-value 0.075 (Student’s paired t test) and +1,35≥AV.RATIO ≤ -1.35. We compared all the spots derived from healthy controls versus all the spots derived from patients and found 65 spots of interest, of these 36 spots were upregulated in the DHSt patients and 29 downregulated. To identify the differentially expressed proteins we performed two preparative gel, but unfortunately the reproducibility of this gel was not 100% and of 65 spots of interest we identified and excised only 51 spots (33 upregulated in the DHSt patients and 18 downregulated). The analysis of peptides extracted from each spot was performed by analysis LC/MS/MS. Mass spectrometric analysis identified 24 proteins. We select 14 protein that could be involved in DHSt, and grouped them on based of their expression: Peptide C-Band3, Flotillin 1 and 2, Stomatin, Peroxiredoxin 1 and 2, Catalase, Annexin A1, Cytovillin 2, RAP2B e RAP1A that resulted up-regulated and G3PD, Aldo A, G protein beta subunit that resulted down-regulated. These data, in particular the discovery of high levels of Peroxiredoxin 1 and 2 and Catalase A1, suggest an increased oxidative stress in patients whit DHSt, also promoted by the decrease of some enzymes of glycolysis are important for the production of NADH and thus reducing potential. Another important data is the increase of Peptice c-Band3 and some proteins involved in the formation of lipid raft (Flotillin 1 and 2, Stomatin and Cytovillin 2) and in the vesciculation (RAP1A and RAP2B). Studies are currently underway to assess phosphorylation of band 3 in DHST patients and red blood cell vesciculation.

The integrity of the red cell membrane depends on molecular interactions between proteins and the phospholipid membrane: vertical interactions stabilize the membrane lipid bilayer; horizontal interactions provide resistance against shear stress. Hereditary spherocytosis—affects 1 in 25 000 individuals of northern European descent. There is typically a dominant family history, but the condition is genetically heterogeneous: combined spectrin and ankyrin deficiency is the most common defect observed, followed by band 3 deficiency, isolated spectrin deficiency, and protein 4.2 deficiency. These affect vertical membrane interactions with loss of surface area relative to red cell volume. Clinical features—the key clinical manifestations are anaemia and signs of persistent haemolysis, with jaundice and a marked propensity to gallstones. Complications and treatment—parvovirus B19 infection of erythropoietic precursors may cause acute aplastic crises. Megaloblastic anaemia due to folate deficiency occurs in response to increased requirements during growth and pregnancy, but is preventable with supplementation. Splenectomy can alleviate the anaemia in many patients and reduces the risk of gallstones. Hereditary elliptocytosis—occurs with a frequency of 1 in 2000 to 1 in 4000 worldwide, and is more frequent in parts of Africa. The inheritance is usually dominant, with defects in red cell proteins such as α‎- and β‎-spectrin causing disturbances in horizontal interactions in the erythrocyte membrane. Clinical features, diagnosis, and treatment—most patients are asymptomatic and are typically diagnosed incidentally during testing for unrelated conditions, but about 10% experience haemolysis, anaemia, splenomegaly, and intermittent jaundice. Diagnosis is based on the presence of elliptocytes on a peripheral blood smear. Treatment is rarely required. Other conditions include hereditary pyropoikilocytosis, South-East Asian (or Melanesian) ovalocytosis, stomatocytosis, and acanthocytosis.

In the past, red cell resting shape could only be assessed by subjective scaling, red cell deformability by a variety of rheological tests that are extremelydifficult to standardize and which all subject the RBC to high deforming forces. None of the latter have been accepted as reference in haematology, haemorheologyor pharmacology. A recent development from our group now allows objective, numerical analysis of red cell membrane curvature (i.e. the echinocytic or stomatocytic deviation from the discocytic resting shape) by a tangent count procedure in optical sections through freely suspended, randomly oriented RBC: (Grebe et al. Biorheology 22(6), 1985). Also, the deformation of point attached erythrocytes under the influence of extremely low shear stresses (0.05 Pa to 0.5 Pa, ARTOANN:Clin. Hemorheology 6, 1986), which are at least two orders of magnitude lower thanthat in any routinely available filtration method allows for the first time to model in vitro the extreme low flow states that occur in severe forms of haemodynamic insufficiency. These two methods in combination are ideally suited for routine tests of drug effects on normal human RBC: the drug action on RS can be monitored continuously during the action of drugs in the suspending medium; likewise, RISA can be recorded automatically on one population of adherent RBC while altering the composition and the drug concentration in the superfusate. The two methods were applied in combination to test rheological and membranological effects of two distinctly different compounds, namely Bencyclan (Bencylan-Hydrogen-Fumarate) and Vinpocitin (Aethyl vincamin) in normal cells and in cells after exposure to "stress conditions", i.e. hyperosmolarity and lactacidosis. Both olrugs given to n o r m a 1 RBC produce stomatocytosis in a done dependent fashion (1-100 uMolar). At shear stresses above o.6 Pa, the RISA is identical to controls, but is oxmsiderably less pronounced at lower shear stresses (T < 0.2 Pa). Thus, drugs of completely olifferent pharmacological action produce clear cut rheological effects on RBC in the micrcmolar concentration range; the combination of methods employed opens new possibilities for the systematic development of haemorheologically active drugs.Supported by DFG:Grant Gr 902/1-1