The Erythrocyte Sedimentation Rate and Its Relation to Cell Shape and Rigidity of Red Blood Cells from Chorea-Acanthocytosis Patients in an Off-Label Treatment with Dasatinib.

BACKGROUND: Chorea-acanthocytosis (ChAc) is a rare hereditary neurodegenerative disease with deformed red blood cells (RBCs), so-called acanthocytes, as a typical marker of the disease. Erythrocyte sedimentation rate (ESR) was recently proposed as a diagnostic biomarker. To date, there is no treatment option for affected patients, but promising therapy candidates, such as dasatinib, a Lyn-kinase inhibitor, have been identified. METHODS: RBCs of two ChAc patients during and after dasatinib treatment were characterized by the ESR, clinical hematology parameters and the 3D shape classification in stasis based on an artificial neural network. Furthermore, mathematical modeling was performed to understand the contribution of cell morphology and cell rigidity to the ESR. Microfluidic measurements were used to compare the RBC rigidity between ChAc patients and healthy controls. RESULTS: The mechano-morphological characterization of RBCs from two ChAc patients in an off-label treatment with dasatinib revealed differences in the ESR and the acanthocyte count during and after the treatment period, which could not directly be related to each other. Clinical hematology parameters were in the normal range. Mathematical modeling indicated that RBC rigidity is more important for delayed ESR than cell shape. Microfluidic experiments confirmed a higher rigidity in the normocytes of ChAc patients compared to healthy controls. CONCLUSIONS: The results increase our understanding of the role of acanthocytes and their associated properties in the ESR, but the data are too sparse to answer the question of whether the ESR is a suitable biomarker for treatment success, whereas a correlation between hematological and neuronal phenotype is still subject to verification.

Alterations of red cell membrane properties in neuroacanthocytosis.

Neuroacanthocytosis (NA) refers to a group of heterogenous, rare genetic disorders, namely chorea acanthocytosis (ChAc), McLeod syndrome (MLS), Huntington's disease-like 2 (HDL2) and pantothenate kinase associated neurodegeneration (PKAN), that mainly affect the basal ganglia and are associated with similar neurological symptoms. PKAN is also assigned to a group of rare neurodegenerative diseases, known as NBIA (neurodegeneration with brain iron accumulation), associated with iron accumulation in the basal ganglia and progressive movement disorder. Acanthocytosis, the occurrence of misshaped erythrocytes with thorny protrusions, is frequently observed in ChAc and MLS patients but less prevalent in PKAN (about 10%) and HDL2 patients. The pathological factors that lead to the formation of the acanthocytic red blood cell shape are currently unknown. The aim of this study was to determine whether NA/NBIA acanthocytes differ in their functionality from normal erythrocytes. Several flow-cytometry-based assays were applied to test the physiological responses of the plasma membrane, namely drug-induced endocytosis, phosphatidylserine exposure and calcium uptake upon treatment with lysophosphatidic acid. ChAc red cell samples clearly showed a reduced response in drug-induced endovesiculation, lysophosphatidic acid-induced phosphatidylserine exposure, and calcium uptake. Impaired responses were also observed in acanthocyte-positive NBIA (PKAN) red cells but not in patient cells without shape abnormalities. These data suggest an "acanthocytic state" of the red cell where alterations in functional and interdependent membrane properties arise together with an acanthocytic cell shape. Further elucidation of the aberrant molecular mechanisms that cause this acanthocytic state may possibly help to evaluate the pathological pathways leading to neurodegeneration.

Familial hypobetalipoproteinemia: early neurological, hematological, and ocular manifestations in two affected twins responding to vitamin supplementation.

Familial hypobetalipoproteinemia is a disorder of lipid metabolism characterized by extremely low plasma levels of apolipoprotein B as well as low levels of total and low-density lipoprotein cholesterol. We report the case of impairment of retinal function and diffuse pain in both legs often related to physical activity, as well as the presence of acanthocytosis on peripheral blood smear. Neurophysiological studies suggested dysfunction of the thin myelinated (A) and unmyelinated (C) fibers, in spite of preserved A fiber function, which has not been previously described in this condition. All clinical symptoms and the neurophysiological abnormalities improved after high-dose vitamin E and A supplementation. These findings suggest that this syndrome may have a wide spectrum of manifestations and an early appearance of symptoms in the pediatric age group.

Structural changes of the erythrocyte as a marker of non-insulin-dependent diabetes: protective effects of N-acetylcysteine.

Prooxidant-antioxidant imbalance was considered as a hallmark of age-associated, non-insulin-dependent diabetes (NIDD). The aim of this ex vivo study was to investigate possible implications of oxidative stress in the integrity and function of red blood cells (RBCs) from NIDD patients. Morphometric and analytical cytology studies were conducted. The results showed: (i) significant alterations of RBC ultrastructure; (ii) relevant changes of spectrin cytoskeleton; (iii) altered insulin receptor distribution; and (iv) that treatment with the antioxidizing drug N-acetylcysteine was capable of significantly counteracting these changes. These results suggest a reconsideration of RBC integrity as a possible progression marker in NIDD.

Effect of phosphatidylserine on the shape of McLeod red cell acanthocytes.

The rare McLeod blood group phenotype is characterized by weak Kell antigens, lack of the common Kx antigen, and acanthocytic morphology. Previous studies that did not detect membrane or cytoskeletal protein abnormalities suggested a lipid disturbance. In normal red cells, dimyristoyl phosphatidylserine (DMPS) is transported across the membrane by an enzymatic process and accumulates in the inner leaflet of the membrane bilayer causing discocyte to stomatocyte shape changes. Scanning electron microscopy of McLeod red cells shows a mixture comprised of 15% discocytes, 51% with irregular surfaces, and 34% acanthocytes. On incubation with various concentrations of DMPS at 37 degrees C for periods up to two hours, McLeod red cells transported DMPS across the membrane and caused irregularly shaped and acanthocytic McLeod red cells to attain normal discocyte shape and later to become stomatocytes. Chlorpromazine, which at 0 degrees C preferentially partitions into the inner monolayer of the membrane, had a similar effect on the shape of McLeod red cells. This suggests that in McLeod cells acanthocytosis is due to a lack of lipid in the inner leaflet of the membrane bilayer but that the imbalance is not caused by defective transport of phosphatidylserine across the membrane.

Effect of Allium ascalonicum on erythrocyte shape in induced hypercholesterolemia rabbits.

The effect of shallot extract on blood lipid levels and erythrocyte shape has been studied in rabbits. Hypercholesterolemia was induced by feeding egg yolk 12.5 g per day for 4 weeks. These rabbits were then divided into 3 groups and were fed with egg yolk alone as control group, egg yolk plus clofibrate 75 mg per day and egg yolk plus 50 g of fresh shallot extract per day respectively. Blood samples were collected from the ear artery every two weeks for evaluating lipid levels and studying morphology of erythrocytes. The abnormal erythrocyte shape (crenation) was strikingly observed in all groups after four weeks of egg yolk feeding with good correlation to lipid levels (r = 0.9, p less than 0.001). The number of crenated erythrocytes decreased continuously by shallot extract from the second week until the eighth week of treatment. This restoring effect could not be seen in the control and clofibrate groups. Lipids levels in all 3 groups did not decrease significantly. This leads to the assumption that there might be some factors other than the lipid-lowering-effect in shallot extract that protect the erythrocyte membrane from deterioration due to high plasma lipid levels.

Shape determinants of McLeod acanthocytes.

We have sought to elucidate the spiculated shape of McLeod erythrocytes. Red cells from a normal donor and from a McLeod patient were incubated in phosphate-buffered saline containing 0, 0.05, or 0.1 mM chlorpromazine at 0 degrees C for 5 min, then glutaraldehyde-fixed, and examined by scanning electron microscopy. The normal red cells were biconcave disks in which chlorpromazine induced inward (negative) curvature: deep cupping (stomatocytosis) and multiple invaginations. The McLeod cells were mostly spiculated. Chlorpromazine at lower concentration converted them into biconcave disks and, at higher concentration, into stomatocytes. These results support the hypothesis that the spiculation of McLeod cells is the result of an imbalance of surface area between the two lipid leaflets of the membrane; that is, a bilayer couple effect. We determined the numerical density of intramembrane particles (IMP) in replicas of both fracture faces of red cells subjected to freeze fracture and rotary shadowing. These values were as follows (expressed per microns 2 of membrane +/- SD): the normal protoplasmic fracture face had 2200 +/- 306 and the McLeod had 2300 +/- 250. The normal exoplasmic fracture face had 388 +/- 75 and the McLeod had 330 +/- 59. We conclude that there is no evidence for derangement of band 3, the principal protein in the IMP, in McLeod erythrocytes.

Tris acetylacetonate aluminium(III) induces osmotic fragility and acanthocyte formation in suspended erythrocytes.

Tris acetylacetonate aluminium(III) (Al(acac)3), dissolved in water, is effective in producing osmotic fragility in suspended erythrocytes in the concentration range of 0.034-0.34 mmol/l. Water solutions of Tris maltolate aluminium(III) (Al(malt)3) and aluminium lactate (Al(lac)3) are also effective but the dose-response behavior is less pronounced. Moreover, only Al(acac)3 induces a prominent generation of acanthocytes. The stronger effects of Al(acac)3 on membrane stability are attributed to the greater solubility of this complex in the cell membrane.

Mechanism of red blood cell acanthocytosis and echinocytosis in vivo.

Patients with abetalipoproteinemia have an inborn absence of the major apoprotein of low density plasma lipoproteins, an abnormal serum and red cell lipid profile, and spiny erythrocytes, called acanthocytes. We now show that these deformed cells are reversibly converted to a normal shape, that of a biconcave disk, by incubation with 3 to 10 X 10(-5) M chlorpromazine. We suppose that chlorpromazine acts by expanding the cytoplasmic leaflet of the bilayer, thus promoting inward curvature. Ghosts isolated from the acanthocytes are themselves spiny but are also converted to normal, concave disks by chlorpromazine or merely by a brief incubation at 37 degrees C in low ionic strength buffer. We attribute the latter to a redistribution of lipids between the two leaflets of the membrane bilayer. Similar observations were made with red cells and ghosts from a patient with benign echinocytosis. These observations suggest that the morphological abnormality in acanthocytes and echinocytes can be ascribed to the same mechanism as crenation in vitro; that is, a bilayer couple effect in which an excess of surface area in the outer leaflet over the inner leaflet of the membrane bilayer drives outward curvature. It is striking that cells which were chronically abnormal in shape in vivo contain the information to become biconcave disks immediately upon simple chemical treatment in vitro.

Acanthocytosis and cholesterol enrichment decrease lipid fluidity of only the outer human erythrocyte membrane leaflet.

The structure and functions of the human erythrocyte are influenced by the composition and organization of the membrane lipids. The outer (exofacial) and inner (endofacial) leaflets of the erythrocyte membrane differ in lipid composition, and recent studies using a group of membrane-impermeant pyrene fluorophores have demonstrated that the lipid fluidity of the outer leaflet exceeds that of the inner. Using one of these probes, pyrene butyryl hydrazide linked to the tetrasaccharide stachyose (SPBH), we have compared the lipid fluidity of the outer and inner leaflets in normal human erythrocytes treated experimentally to alter membrane cholesterol content and in acanthocytes, erythrocytes of altered morphology found in individuals with the genetic disorder abetalipoproteinaemia. The results, reported here, demonstrate that hemileaflet fluidity can be altered selectively: acanthocytosis and experimental cholesterol enrichment decrease the lipid fluidity of the outer but not the inner hemileaflet.