A basis of the acanthocytosis in inherited and acquired disorders

Alteration in the number, morphology, function, and metabolism of erythrocytes in high-altitude polycythemia

Introduction: High-altitude polycythemia (HAPC) is a common chronic high-altitude disease characterized by significantly increased erythrocyte, hemoglobin (Hb), and hematocrit values and decreased arterial oxygen saturation. The mechanisms underlying HAPC development are unclear; we aimed to investigate this in an HAPC rat model. Methods: Twelve Sprague-Dawley rats were divided into control and HAPC groups. The HAPC group was exposed to hypobaric hypoxia. This HAPC model was assessed using routine blood tests and blood gas analyses. Bone marrow, peripheral blood reticulocytes (RETs), and peripheral blood erythrocyte apoptosis were measured using flow cytometry. Erythrocyte osmotic fragility (EOF) tests were conducted. Abnormal erythrocytes were counted using electron microscopy. Plasma-free hemoglobin, 5'-nucleotidase (CD73), adenosine, erythrocyte cytosolic adenosine, sphingosine-1-phosphate (S1P), and 2,3-bisphosphoglycerate (BPG) levels were measured using enzyme-linked immunosorbent assays. Erythrocyte metabolic pathway-related protein [adenosine A2B receptor (ADORA2B), erythrocyte equilibrative nucleoside transporter 1 (eENT1), sphingosine kinase 1 (SPHK1), phospho-SPHK1, bisphosphoglycerate mutase (BPGM), and glyceraldehyde 3-phosphate dehydrogenase (GAPDH)] levels were assessed by Western blotting. Results: The HAPC rat model was successfully established (Hb > 210 g/L). Indices of bone marrow and peripheral blood RET proportions were significantly higher in the HAPC than the control group (p = 0.04 and p < 0.001, respectively). The proportion of peripheral blood erythrocytes in early apoptosis was significantly lower in the HAPC than the control group (p < 0.001). Vesicular erythrocyte and acanthocyte proportions were significantly higher in the HAPC than the control group (p < 0.001 and p = 0.019, respectively). The EOF tests revealed that 50% erythrocyte hemolysis occurred at 4.0-4.5 and 4.5-5.0 g/L NaCl in the control and HAPC groups, respectively. Plasma-free hemoglobin, CD73, adenosine, erythrocyte cytosolic adenosine, S1P, and 2,3-BPG levels and ADORA2B, eENT1, phospho-SPHK1, S1P, BPGM, and GAPDH erythrocyte expression levels (all p ≤ 0.02) were significantly higher in the HAPC than the control group. Conclusion: In model rats, an HAPC-related erythrocyte increase was associated with enhanced bone marrow hematopoietic function and reduced erythrocyte apoptosis, whereas numerous abnormal erythrocytes, increased EOF, and reduced hemolysis resistance were associated with erythrocyte metabolism. CD73/adenosine/S1P/2,3-BPG and eENT1/adenosine/BPGM/2,3-BPG metabolic pathways in erythrocytes were activated in HAPC rats, facilitating oxygen release. These findings further reveal the intrinsic HAPC mechanism and forms a basis for future development of preventive and therapeutic strategies for HAPC.

Lauric Acid, a Dietary Saturated Medium-Chain Fatty Acid, Elicits Calcium-Dependent Eryptosis

Cardiovascular diseases (CVD) are a leading cause of mortality worldwide, and dietary habits represent a major risk factor for dyslipidemia; a hallmark of CVD. Saturated fatty acids contribute to CVD by aggravating dyslipidemia, and, in particular, lauric acid (LA) raises circulating cholesterol levels. The role of red blood cells (RBCs) in CVD is increasingly being appreciated, and eryptosis has recently been identified as a novel mechanism in CVD. However, the effect of LA on RBC physiology has not been thoroughly investigated. RBCs were isolated from heparin-anticoagulated whole blood (WB) and exposed to 50-250 μM of LA for 24 h at 37 °C. Hemoglobin was photometrically examined as an indicator of hemolysis, whereas eryptosis was assessed by Annexin V-FITC for phosphatidylserine (PS) exposure, Fluo4/AM for Ca²⁺, light scatter for cellular morphology, H₂DCFDA for oxidative stress, and BODIPY 581/591 C11 for lipid peroxidation. WB was also examined for RBC, leukocyte, and platelet viability and indices. LA caused dose-responsive hemolysis, and Ca²⁺-dependent PS exposure, elevated erythrocyte sedimentation rate (ESR), cytosolic Ca²⁺ overload, cell shrinkage and granularity, oxidative stress, accumulation of lipid peroxides, and stimulation of casein kinase 1α (CK1α). In WB, LA disrupted leukocyte distribution with elevated neutrophil-lymphocyte ratio (NLR) due to selective toxicity to lymphocytes. In conclusion, this report provides the first evidence of the pro-eryptotic potential of LA and associated mechanisms, which informs dietary interventions aimed at CVD prevention and management.

Bioymifi, a novel mimetic of TNF-related apoptosis-induced ligand (TRAIL), stimulates eryptosis

Tumor necrosis factor-related apoptosis-induced ligand (TRAIL) is a cytokine that initiates apoptosis upon binding to death receptor 5 (DR5) on cancer cells. Small molecule TRAIL mimetics have therefore been investigated as promising chemotherapeutic agents. Since anemia of chemotherapy is common, our goal is to investigate the hemolytic and eryptotic properties of novel DR5 agonist bioymifi (BMF) and identify the underlying molecular mechanisms. Whole blood (WB) was stimulated with 100 μM of BMF, whereas red blood cells (RBCs) were treated with 10-100 μM of BMF for 24 h at 37 °C. WB was analyzed for RBC, leukocyte, and platelet indices, while RBCs were examined for hemolysis by light absorbance of free hemoglobin, membrane scrambling by Annexin V-FITC, calcium by Fluo4/AM, cellular morphology by light scatter, and oxidative stress by 2',7'-dichlorodihydrofluorescein diacetate (H₂DCFDA) using flow cytometry. Caspase inhibitor Z-VAD-FMK, p38 inhibitor SB203580, casein kinase 1α inhibitor D4476, receptor-interacting protein 1 inhibitor necrostatin-2, reduced glutathione, or cyclooxygenase (COX) inhibitor aspirin were added accordingly. BMF exerted dose-responsive, calcium-independent hemolysis, reduced RBC hemoglobin, significantly increased Annexin V-, Fluo4-, and DCF-positive cells, along with a dual effect on forward and side light scatter. Notably, the cytotoxic potential of BMF was significantly mitigated upon pharmacological inhibition of p38. Furthermore, BMF exhibited selective toxicity to eosinophils and significantly diminished reticulocyte hemoglobin content. Altogether, these novel findings highlight the adverse outcomes of BMF exposure on RBC physiology and provide the first toxicological assessment of BMF as an antitumor agent.

Impaired Cytoskeletal and Membrane Biophysical Properties of Acanthocytes in Hypobetalipoproteinemia - A Case Study

Familial hypobetalipoproteinemia is a metabolic disorder mainly caused by mutations in the apolipoprotein B gene. In its homozygous form it can lead without treatment to severe ophthalmological and neurological manifestations. In contrast, the heterozygous form is generally asymptomatic but associated with a low risk of cardiovascular disease. Acanthocytes or thorny red blood cells (RBCs) are described for both forms of the disease. However, those morphological changes are poorly characterized and their potential consequences for RBC functionality are not understood. Thus, in the present study, we asked whether, to what extent and how acanthocytes from a patient with heterozygous familial hypobetalipoproteinemia could exhibit altered RBC functionality. Acanthocytes represented 50% of the total RBC population and contained mitoTracker-positive surface patches, indicating the presence of mitochondrial fragments. While RBC osmotic fragility, calcium content and ATP homeostasis were preserved, a slight decrease of RBC deformability combined with an increase of intracellular free reactive oxygen species were observed. The spectrin cytoskeleton was altered, showing a lower density and an enrichment in patches. At the membrane level, no obvious modification of the RBC membrane fatty acids nor of the cholesterol content were detected but the ceramide species were all increased. Membrane stiffness and curvature were also increased whereas transversal asymmetry was preserved. In contrast, lateral asymmetry was highly impaired showing: (i) increased abundance and decreased functionality of sphingomyelin-enriched domains; (ii) cholesterol enrichment in spicules; and (iii) ceramide enrichment in patches. We propose that oxidative stress induces cytoskeletal alterations, leading to increased membrane stiffness and curvature and impaired lipid lateral distribution in domains and spicules. In addition, ceramide- and spectrin-enriched patches could result from a RBC maturation defect. Altogether, the data indicate that acanthocytes are associated with cytoskeletal and membrane lipid lateral asymmetry alterations, while deformability is only mildly impaired. In addition, familial hypobetalipoproteinemia might also affect RBC precursors leading to disturbed RBC maturation. This study paves the way for the potential use of membrane biophysics and lipid vital imaging as new methods for diagnosis of RBC disorders.

A multi-centre case series of alectinib-related erythrocyte membrane changes and associated haemolysis

Alectinib is an orally bioavailable anaplastic lymphoma kinase (ALK) inhibitor indicated for ALK mutated non-small cell lung cancer (NSCLC). This case series documents the development of significant erythrocyte membrane changes associated with alectinib use in six patients. Morphological findings found on blood film examination include moderate-marked acanthocytes, spheroacanthocytes, and one case demonstrated moderate schistocytes. Two patients in this multi-centre case series developed grade 1 anaemia, and four patients developed grade 2 anaemia. Two patients suffered significant non-immune-related haemolysis. One patient had a co-existing β thalassaemia trait and required treatment cessation due to severe haemolysis. Low-grade anaemia was seen in 22% of patients using alectinib in the ALEX trial and 5% developed ≥ grade 3 anaemia. Alterations in erythrocyte morphology and membrane structure have not been reported in the safety data and clinical trials to date. Drug-induced acanthocytosis is a rare phenomenon and has previously been reported with high-dose prostaglandin administration only. This case series highlights this important laboratory finding with alectinib use and associated clinical sequelae. Alectinib-associated acanthocytosis is likely to be more prevalent than previously recognised. We also highlight the need for vigilance in haematopathology departments for unexpected laboratory findings associated with novel therapies. These findings can be detected in the post-marketing surveillance phase and may have serious clinical implications for patients.

Chronic Granulomatous Disease with the McLeod Phenotype: a French National Retrospective Case Series

BACKGROUND

X-linked chronic granulomatous disease (CGD) is a primary immunodeficiency caused by mutations in the CYBB gene (located on Xp21.1). Patients with large deletions on chromosome Xp21.1 can present with the McLeod phenotype and also Duchenne muscular dystrophy or retinitis pigmentosa. The objective of the present study was to describe a series of French patients with CGD and the McLeod phenotype.

METHODS

We retrospectively collected data from the medical records of 8 patients with CGD and the McLeod phenotype registered at the French National Reference Center for blood types.

RESULTS

The median age at diagnosis of CGD was 1.2 years, the median age at diagnosis of the McLeod phenotype was 4.5 years, and the median length of follow-up was 15.2 years. Four patients displayed allo-immunization, with anti-KEL20 and anti-XK1 (formerly known as anti-KL) antibodies. Five of the 6 patients with available blood smears had acanthocytosis. Neuropsychiatric, muscle-related, and ocular manifestations were present in 4, 2, and 1 of the patients, respectively. Three of the 4 patients having undergone allogeneic hematopoietic stem cell transplantation (HSCT) are alive. Overall, 5 patients are alive, and 3 are alive and well.

CONCLUSION

This is the largest yet descriptive study of a series of patients with X-linked CGD and the McLeod phenotype. Although this disease combination is rare, the timely, accurate diagnosis of the McLeod phenotype is critical because of the serious post-transfusion complications. However, HSCT can be considered in these patients.

A hypothesis of target cell formation in sickle cell disease

A fraction of erythrocytes appear as target cells in stained blood smears in sickle cell disease, due to a inheritance of the hemoglobin variant Hb S, polymerizing upon deoxygenation. These cells appear in a three dimension as thin cups. A process of their formation in this disease is proposed based on a band 3-based mechanism of the erythrocyte shape control, able to explain the erythrocyte echinocytosis by glucose depletion. It indicates that their formation is due to a stomatocytogenic slow outward transport of the dibasic form of endogenous Pi with an H(+) by band 3, promoted by the decrease of the Donnan ratio, which decreases cell pH and volume, attributed by a decrease of cell KCl concentration by the higher efflux of K(+)Cl(-) cotransport and Ca(2+) activation of the Gardos channel. Its implications are briefly discussed with respect to target cells per se, target cell formation in other hemoglobinopathies, acquired and inherited disorders of the lipid metabolism and dehydrated hereditary stomatocytosis as well as a stomatocyte presence in a double heterozygote of Hb S and Hb C and of an involvement of the process of target cell formation in acanthocytosis in acquired and inherited disorders.

Serum metabolomic profiling in acute alcoholic hepatitis identifies multiple dysregulated pathways

BACKGROUND AND OBJECTIVES

While animal studies have implicated derangements of global energy homeostasis in the pathogenesis of acute alcoholic hepatitis (AAH), the relevance of these findings to the development of human AAH remains unclear. Using global, unbiased serum metabolomics analysis, we sought to characterize alterations in metabolic pathways associated with severe AAH and identify potential biomarkers for disease prognosis.

METHODS

This prospective, case-control study design included 25 patients with severe AAH and 25 ambulatory patients with alcoholic cirrhosis. Serum samples were collected within 24 hours of the index clinical encounter. Global, unbiased metabolomics profiling was performed. Patients were followed for 180 days after enrollment to determine survival.

RESULTS

Levels of 234 biochemicals were altered in subjects with severe AAH. Random-forest analysis, principal component analysis, and integrated hierarchical clustering methods demonstrated that metabolomics profiles separated the two cohorts with 100% accuracy. Severe AAH was associated with enhanced triglyceride lipolysis, impaired mitochondrial fatty acid beta oxidation, and upregulated omega oxidation. Low levels of multiple lysolipids and related metabolites suggested decreased plasma membrane remodeling in severe AAH. While most measured bile acids were increased in severe AAH, low deoxycholate and glycodeoxycholate levels indicated intestinal dysbiosis. Several changes in substrate utilization for energy homeostasis were identified in severe AAH, including increased glucose consumption by the pentose phosphate pathway, altered tricarboxylic acid (TCA) cycle activity, and enhanced peptide catabolism. Finally, altered levels of small molecules related to glutathione metabolism and antioxidant vitamin depletion were observed in patients with severe AAH. Univariable logistic regression revealed 15 metabolites associated with 180-day survival in severe AAH.

CONCLUSION

Severe AAH is characterized by a distinct metabolic phenotype spanning multiple pathways. Metabolomics profiling revealed a panel of biomarkers for disease prognosis, and future studies are planned to validate these findings in larger cohorts of patients with severe AAH.

Klippel-Trenaunay syndrome presenting with acanthocytosis and splenic and retroperitoneal lymphangioma: a case report

Introduction

Klippel-Trenaunay syndrome is a rare congenital mesodermal abnormality characterized by bone and soft tissue hypertrophy, extensive hemangioma and venous abnormalities. We report the case of a patient with two additional rare clinical manifestations in the background of Klippel-Trenaunay syndrome, namely, acanthocytosis and splenic and retroperitoneal lymphangioma.

Case presentation

A 24-year-old Sri Lankan man from North Central Province in Sri Lanka presented to our general medical unit with symptomatic anaemia. He had been diagnosed with Klippel-Trenaunay syndrome at the age of six years, with hemihypertrophy of his right lower limb and strawberry naevi over both lower limbs. His blood film results were positive for acanthocytes, which accounted for more than 20% of the red blood cell population. He was also found to have extensive splenic lymphangiomas and a large retroperitoneal lymphangioma encasing the mesentric vessels in the right para-aortic region. An extensive battery of tests to identify a secondary cause for the acanthocytosis failed to show any positive results.

Conclusions

Retroperitoneal lymphangioma has been reported in association with Klippel-Trenaunay syndrome once before, but an association with acanthocytosis has never been reported. Given the rarity of all three conditions this is not surprising. The cause of acanthocytosis in this setting is currently unresolved. It is plausible that this may be a primary association with Klippel-Trenaunay syndrome, as an alternative aetiology was not found.

Imaging flow cytometry for automated detection of hypoxia-induced erythrocyte shape change in sickle cell disease

In preclinical and early phase pharmacologic trials in sickle cell disease, the percentage of sickled erythrocytes after deoxygenation, an ex vivo functional sickling assay, has been used as a measure of a patient's disease outcome. We developed a new sickle imaging flow cytometry assay (SIFCA) and investigated its application. To perform the SIFCA, peripheral blood was diluted, deoxygenated (2% oxygen) for 2 hr, fixed, and analyzed using imaging flow cytometry. We developed a software algorithm that correctly classified investigator tagged "sickled" and "normal" erythrocyte morphology with a sensitivity of 100% and a specificity of 99.1%. The percentage of sickled cells as measured by SIFCA correlated strongly with the percentage of sickle cell anemia blood in experimentally admixed samples (R = 0.98, P ≤ 0.001), negatively with fetal hemoglobin (HbF) levels (R = -0.558, P = 0.027), negatively with pH (R = -0.688, P = 0.026), negatively with pretreatment with the antisickling agent, Aes-103 (5-hydroxymethyl-2-furfural) (R = -0.766, P = 0.002), and positively with the presence of long intracellular fibers as visualized by transmission electron microscopy (R = 0.799, P = 0.002). This study shows proof of principle that the automated, operator-independent SIFCA is associated with predictable physiologic and clinical parameters and is altered by the putative antisickling agent, Aes-103. SIFCA is a new method that may be useful in sickle cell drug development.

The hematology of anorexia nervosa

OBJECTIVE

Changes of the peripheral blood cell count in patients with anorexia nervosa (AN) are frequent. Anemia and leukopenia are observed in one-third of these patients. Examination of the bone marrow reveals in almost 50% of the patients with AN signs of bone marrow atrophy and can additionally suffer from a gelatinous bone marrow transformation.

METHOD

Published studies and investigations concerning hematological changes in patients with AN were reviewed.

RESULTS

Anemia and mild neutropenia are detectable in almost one-third of these patients, whereas thrombocytopenia is rather uncommon. The exact mechanism for these findings is still unclear, but 50% of AN-patients with hematological changes display morphological signs of partial bone marrow atrophy.

DISCUSSION

Changes of the peripheral blood cell count in patients with AN is a frequent observation but the peripheral blood cell count cannot predict the severity of bone marrow atrophy. All hematological and morphological alterations disappear completely and rapidly after sufficient refeeding.

Chorea-acanthocytosis: A Mimicker of Huntington Disease Case Report and Review of the Literature

BACKGROUND

Neuroacanthocytosis consists of a group of rare heterogeneous neurodegenerative disorders associated with acanthocytosis. Chorea-acanthocytosis, a variety of neuroacanthocytosis, is an autosomal recessive condition with clinical and radiologic features similar to Huntington disease. Although difficult, distinguishing between these entities is crucial as the implications for genetic counseling are significant.

REVIEW SUMMARY

We report the case of a 33-year-old female who presented to our institution with a 3-year history of chorea. The patient's prominent orofacial symptoms and the presence of acanthocytes on peripheral blood smear led to the correct diagnosis of chorea-acanthocytosis.

CONCLUSIONS

The significant similarities between chorea-acanthocytosis and Huntington disease at the clinical and radiologic levels can lead to an initial misdiagnosis. Clinical clues suggestive of chorea-acanthocytosis include prominent orofacial dyskinesias, often causing dysarthria and dysphagia. Acanthocytosis, when present on peripheral blood smear, can confirm the diagnosis.

The behavior of the human erythrocyte as an imperfect osmometer: A hypothesis

The human erythrocyte does not behave as a perfect osmometer that is its volume does not change as predicted with the change of the tonicity of the medium, as if there was a fraction of the cell water not participating in the osmotic exchange. A mechanism of control of the erythrocyte shape has been previously proposed in which Band 3 (AE1), the protein anion exchanger of Cl(-) and HCO(3)(-), plays a central role. Specifically, decrease and increase of the ratio of its outward-facing conformation and inward-facing conformation (Band 3(o)/Band 3(i)) contract and relax the membrane skeleton, thus favoring echinocytosis and stomatocytosis, respectively. The equilibrium Band 3(o)/Band 3(i) ratio is determined by the Donnan equilibrium ratio of anions and protons, increasing with it (r=Cl(i)(-)/Cl(o)(-)=HCO 3(i)(-)/HCO 3(o)(-)=H(o)(+)/H(i)(+)). The Donnan ratio is influenced by the erythrocyte transport and metabolic activities. The volume change of the human erythrocyte alters the skeleton conformation as it is accompanied by a change of the membrane curvature. Thus, the mechanism could be a hypothesis for explaining the behavior of the human erythrocyte as an imperfect osmometer since the Donnan ratio controls the Band 3(o)/Band 3(i) ratio which controls the volume by a control of the degree of contraction or relaxation of the skeleton. Predictions made by the hypothesis on the Ponder's coefficient R' values in the presence of sucrose or Band 3 substrates slowly transported as well as on the participation of Band 3 in the osmotic hemolysis appear to be corroborated by previous observations. If the hypothesis was valid, it would follow that there is a pressure gradient across the erythrocyte membrane. The equilibrium volume is antagonistically determined by the Donnan ratio per se and Band 3. Band 3, rather than the ratio of surface-to-volume, primarily controls the osmotic hemolysis.

Neuroacanthocytosis

PURPOSE OF REVIEW

The term neuroacanthocytosis describes a group of phenotypically and genetically heterogeneous disorders, and thus has long been a source of confusion and diagnostic imprecision. It is vital to distinguish between the lipoprotein deficiency disorders which affect gait, but do not cause movement disorders or neuropsychiatric problems, and the diseases described here, of which these are characteristic features. This review summarizes the current state of knowledge regarding this group of diseases in order to facilitate clinical recognition, accurate diagnosis and appropriate management.

RECENT FINDINGS

Advances in molecular medicine have enabled us to distinguish precisely among the disorders described under the label of neuroacanthocytosis, most notably between autosomal recessive chorea-acanthocytosis and the X-linked McLeod syndrome. This has facilitated appreciation of the range of phenotypes in each of the various conditions. Acanthocytosis is also found in a smaller percentage of cases with pantothenate kinase-associated neurodegeneration (PKAN) and Huntington's disease-like 2 (HDL2). An improved method of determination of acanthocytosis has been described, which if adopted as standard practice may facilitate detection of these conditions.

SUMMARY

Genetic testing has led to increased diagnostic accuracy of the neuroacanthocytosis syndromes, which is essential to extend recognition of these disorders, as well as to improve understanding of the disease process. Most importantly, given the absence of a cure, it is vital for appropriate genetic counselling. Treatments, as in other neurodegenerative conditions, are at present limited to symptomatic therapies.

A hypothesis of the disc-sphere transformation of the erythrocytes between glass surfaces and of related observations

Erythrocytes suspended at a low hematocrit in a non-buffered isotonic saline change from biconcave discs to spheres between glass surfaces of a slide and of a coverslip with the echinocyte as an intermediate. A pH increase is a major factor responsible for this disc-sphere transformation or glass effect. It is also observed between surfaces made of various polymers and of mica provided that the distance between them is controlled (0.1 mm). The glass effect is antagonized by serum, plasma, serum albumin, ammonium salts and CO2. It is not observed above a 1-2% hematocrit, but is enhanced by gamma-globulins. The sites of reappearance of the spicules are the same and the order of their disappearance is the inverse of the order of their reappearance during the repetitive cycle of the disc-sphere transformation and reversal when a small glass rod is alternatively approached near a site on the erythrocyte surface and withdrawn. A mechanism of erythrocyte shape control has been previously hypothesized in which Band 3 (AE1), the anion exchange protein, plays a central role. Specifically, decrease and increase of the ratio of its outward-facing conformation (Band 3o) and inward-facing conformation (Band 3i) contract and relax the membrane skeleton, promoting the echinocytosis and stomatocytosis, respectively. The Band 3o/Band 3i equilibrium ratio is determined by the Donnan equilibrium ratio of Cl-, HCO3- and H+ (r=Cl(i)-/Cl(o)-=HCO3i-/HCO3o-=Ho+/Hi+), increasing with it. The mechanism could explain by a change of the Donnan ratio the above observations with the assumptions that polymers are permeable to CO2 and that an unstirred layer slows the propagation of the change occurring at the site of approach of the glass rod to peripheral sites. The presence of HCO3- in serum or plasma may be the basis for the absence of the glass effect in these fluids.