Cryohemolysis, erythrocyte osmotic fragility, and supplementary hematimetric indices in the diagnosis of hereditary spherocytosis

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.

Utility of Cryohemolysis Test in the Diagnosis of Hereditary Spherocytosis

Diagnosis of Hereditary spherocytosis (HS) often requires time-consuming and/or expensive tests. Cryohemolysis test (CHT) is a simple and easy to perform test with high predictive value for HS diagnosis. In this prospective study, we evaluated the diagnostic utility of CHT for the diagnosis of HS. We included 60 suspected HS patients, 18 patients with Autoimmune hemolytic anemia (AIHA) and 120 healthy controls. Among the 60 suspected cases, there were 36 HS cases and 24 with other hemolytic anemias. The mean CHT (%) ± SD for controls, AIHA, other hemolytic anemias, and HS was 6.63 ± 2.79, 6.79 ± 4.36, 6.61 ± 2.76 and 26.7 ± 8.9, respectively. The CHT % was significantly higher in HS group when compared to controls (p =  < 0.0001), AIHA (p =  < 0.0001) and other hemolytic anemia groups (p =  < 0.0001). At a CHT cut off of > 18.3%, the sensitivity, specificity, positive predictive value and negative predictive value for diagnosis of HS in our study were 97.1%, 94.4%, 97.2% and 90.3%, respectively. CHT is a simple and sensitive test for the diagnosis of HS but remains underutilized. The addition of CHT in the diagnostic workup of HS will be very useful, especially in a resource limited setting.

Signaling Pathway in the Osmotic Resistance Induced by Angiotensin II AT2 Receptor Activation in Human Erythrocytes

Background

Angiotensin II regulates blood volume via AT1 (AT1R) and AT2 (AT2R) receptors. As cell integrity is an important feature of mature erythrocyte, we sought to evaluate, in vitro, whether angiotensin II modulates resistance to hemolysis and the signaling pathway involved.

Methods

Human blood samples were collected and hemolysis assay and angiotensin II signaling pathway profiling in erythrocytes were done.

Results

Hemolysis assay created a hemolysis curve in presence of Ang II in several concentrations (10^-6 M, 10^-8 M, 10^-10 M, 10^-12 M). Angiotensin II demonstrated protective effect, both in osmotic stressed and physiological situations, by reducing hemolysis in NaCl 0.4% and 0.9%. By adding receptors antagonists (losartan, AT1R antagonist and PD 123319, AT2R antagonist) and/or signaling modulators for AMPK, Akt/PI3K, p38 and PKC we showed the protective effect was enhanced with losartan and abolished with PD 123319. Also, we showed activation of p38 as well as PI3K/Akt pathways in this system.

Conclusion

Ang II protects human erythrocytes from hypo-osmotic conditions-induced hemolysis by activating AT2 receptors and triggering intracellular pathways.

Phytocomponents from Anacardium occidentale, Psidium guajava, and Terminalia catappa altered membrane osmotic stability of sickle erythrocytes

Background

The present study identified, quantified, and characterized the combinations of phytocomponents from fractionated leaf extracts of Anacardium occidentale, Psidium guajava, and Terminalia catappa that stabilized sickle erythrocyte membrane against osmotic stress, or otherwise, using standard chromatographic-spectrophotometric techniques, namely GC-MS, FT-IR, and UV-visible systems.

Results

The percentage hemolysis of the control sample, in 0.9 g/100 mL NaCl, was 35.08 ± 11.64%, whereas those of the samples containing 40 mg/100 mL, 60 mg/100 mL, and 80 mg/100 mL of ethylacetate extracts of T. catappa ranged between 31.82 ± 8.32 and 39.18 ± 6.94%. Ethylacetate extract of T. catappa contained comparative high quantities of hexadecanoic acid methyl ester, 9,11-octadecadienoic acid, methyl ester, (E, E)-, trans-13-octadecenoic acid methyl ester, and methyl stearate. FT-IR and UV-visible spectra showed that ethylacetate extract of T. catappa contained aromatic compounds as well as nitro-compounds, phenolics, and esters.

Conclusion

To mention but a few, the combinations of major phytocomponents that stabilized sickle erythrocyte membrane against osmotic stress were hexadecanoic acid, methyl ester, 11-octadecenoic acid, methyl ester, dibutyl phthalate, pentacosane, trans-13-octadecenoic acid, methyl ester, whereas the minor phytocomponents include methyl tetradecanoate, methoxyacetic acid, 3-pentadecyl ester, methyl stearate, hexadecanoic acid, isoxazole, 4,5-dimethyl-.

Old and new insights into the diagnosis of hereditary spherocytosis

Hereditary spherocytosis (HS) belongs to the group of congenital hemolytic anemias resulting from plasma membrane protein deficiency. When diagnosed too late, HS bares the risk of long-term complications including gall stones and severe anemia. Here, there are discussed advances in HS screening and diagnostics, with a particular focus on methodologies, most of which are available in clinical laboratories worldwide.