Alterations in Vascular Endothelial Cell-related Plasma Proteins In Thalassaemic Patients and their Correlation with Clinical Symptoms

An increased level of plasma thrombomodulin (TM) in α- and β- thalassaemia was demonstrated using an enzyme-linked immunosorbent assay (ELISA). Nonsplenectomized patients with β-thalassaemia/ haemoglobin E (BE) had higher levels of TM than splenectomized cases (BE-S). Patients with leg ulcers (BE-LU) were found to have the highest increase in TM level. Appearance of larger platelets in all types of thalassaemic blood was observed indicating an increase in the number of younger platelets. These data indicate that injury of vascular endothelial cells is present in thalassaemic patients.

Cytoadherence between endothelial cells and P. falciparum infected and noninfected normal and thalassemic red blood cells

BACKGROUND

Cytoadhesion of P. falciparum infected red blood cells (RBCs) to endothelial cells (ECs) is an important phenomenon that causes cerebral malaria in man. Reduced adhesion especially in thalassemia and hemoglobinopathies may be related to a protective mechanism against malaria in such people.

METHODS

The cytoadherence assay was performed using both conventional and floating conditions between ECs (ECV 304) and P. falciparum infected and noninfected RBCs from both normal and thalassemia subjects. In floating condition, RBC was fluorescently labeled with anti-glycophorin A antibody, whereas EC was identified by surface expression of PECAM-1, CD-36, ICAM-1, and E-selectin. The condition of floating EC was similar to the condition for subcultivation as they can adhere or bind to any surface. The phosphatidylserine (PS) exposure was also determined by using flow cytometer.

RESULTS

The adhesion of noninfected heterozygous thalassemic RBCs (all genotypes) to ECs was significantly increased as compared with normal RBCs (P < 0.02). Interestingly, after P. falciparum infection, the number of normal RBCs bound to ECs was significantly increased as compared with noninfected RBCs (P < 0.01), whereas heterozygous thalassemic RBCs infected by P. falciparum showed no significant difference compared with noninfected RBCs. In addition, we found a similar level of PS exposure in normal and thalassemic infected RBCs, which was related to the cytoadherence phenomenon.

CONCLUSION

The reduced adhesion between heterozygous thalassemic RBCs infected by P. falciparum to ECs provides an explanation for their protective mechanism against malaria, as increased adhesion is a high risk for cerebral malaria and nonbinding infected RBCs can be removed by the reticuloendothelial system and other mechanism(s) in vivo.

Reticulocyte analysis in iron deficiency anemia and hemolytic anemia

Reticulocyte analysis was studied in 28 anemic patients, 15 with iron deficiency anemia (IDA), and 13 with hemolytic anemia including 9 glucose 6 phosphate dehydrogenase deficiency (G6PD def.), and 4 with G6PD def. combined with HbE trait or alpha thalassemia trait (alpha thal trait). The reticulocyte analysis among these patients showed the increased number of reticulocyte percentage with low degree of maturation in both IDA and G6PD def. patients. The significantly decreased reticulocyte hemoglobin content (CHr) was found in IDA (CHr = 21.74 +/- 4.61 pg in IDA vs 28.41 +/- 1.34 pg in normal; p-value = < 0.0001), whereas, increased CHr was found in G6PD def. patients. In addition, the G6PD def. patients also showed a significant increase in mean corpuscular reticulocyte volume (MCVr) when compared to normal (MCVr = 132.0 +/- 8.39 fl. in G6PD def. vs 110.39 +/- 5.09 in normal; p-value = < 0.0001). However, a significant decrease in MCVr was found in IDA patients (MCVr = 95.89 +/- 8.57 fl.; p-value = < 0.0001 vs normal). From this study, we can suggest that the reticulocyte hemoglobin content (CHr) and mean corpuscular reticulocyte volume (MCVr) are the important defects in patients with iron deficiency anemia.

Enhanced tumor necrosis factor in the serum and renal hypoperfusion in nephrosis associated with focal segmental glomerulosclerosis

Enhanced tumor necrosis factor alpha associated with immunocirculatory imbalance expressed as increased ratio between proinflammatory (TNFalpha) and antiinflammatory (IL-10) cytokines was observed in the serum of nephrosis associated with focal segmental glomerulosclerosis. Such altered immunocirculatory balance correlated with the reduction in renal plasma flow determined by the intrarenal hemodynamic study by which it implies that a glomerular endothelial cell injury associated with impaired renal perfusion is likely to be spontaneously induced by enhanced tumor necrosis factor in the presence of inadequate release of antiinflammatory cytokine (IL-10).

Reticulocyte analysis in systemic lupus erythematosus and chronic renal failure using flow cytometry

The number and maturation of circulating reticulocytes were measured in patients with systemic lupus erythematosus (SLE) and chronic renal failure (CRF) using an automated hematological analyzer (Technicon H*3 RTX) for their erythropoietic activities. Both SLE and CRF patients had increased reticulocyte numbers with a low degree of maturation. The SLE patients had no changes in mean reticulocyte corpuscular volume (MCVr) as compared to normal subjects (110.20 +/- 15.43 fl. in SLE and 110.39 +/- 5.09 fl. in normal), whereas CRF patients had significantly increased mean corpuscular reticulocyte volume (MCVr = 120.99 +/- 8.09 fl., p-value = 0.0019 as compared with normal). Three cases of SLE with nephrotic syndrome (NS) had high degree of MCVr (113.4, 125.0 and 133.1 fl., respectively). The renal involvement in SLE patients and CRF patients may associate with increased reticulocyte corpuscular volume.

Dengue viruses induce cell proliferation and morphological changes of endothelial cells

Replication of dengue viruses (type 1, 2, 3 and 4) in vitro in endothelial cells from human umbilical cord vein was demonstrated by virus titers and immunofluorescent antibody studies. Both showed highest peak at Day 6 after inoculation and declined to origin at Day 14. Some of the cultured endothelial cells detached from the culture well. Most of these floating cells were rarely viable as shown by failure in trypan blue exclusion whereas the adhering cells are mostly viable. More frequent and higher intensity of immunofluorescent positive cells were found in the detached cells as compared to adhering cells. The virus titers in the supernatant and in the adhering cell population were comparable, although floating cells were maximally 26.2% of the total cultured endothelial cells. Many floating cells and occasional adhering cells had numerous blebs on their surface. Endothelial cell proliferation was markedly increased after virus inoculation as compared with the control. Increased number of mitotic cells was also observed in the dengue virus-endothelial cell culture. Comparing among the four types, dengue type 4 induced highest peaks of cell proliferation and cell mitosis at Day 10 after inoculation. Dengue type 2 had the highest virus titers both in adhering cells and in supernatant at Day 6 as compared with other types.

Malaria protection in hereditary ovalocytosis: relation to red cell deformability, red cell parameters and degree of ovalocytosis

In the culture of red cells with Plasmodium falciparum, erythrocytes from both Thai patients and subjects (patient's parents) with hereditary ovalocytosis have a protective effect against malarial infection. High percentage of ovalocyte (75-100%) was found in patients whereas their parents had lower percentage (25-50%). Invasion index (II) and multiplication ratio (MR) of P. falciparum in these abnormal red cells from the patients were significantly decreased as compared to those in normal red cells (patients: II = 1.52 +/- 0.91, MR = 8.83 +/- 6.73; normal subjects: II = 4.45 +/- 1.51, MR = 25.23 +/- 6.25). This suggests that the red cells from these patients had significant degree of malaria protection. The significant protection was also shown in red cells from the parent group (II = 1.86 +/- 0.81, MR = 15.69 +/- 3.50). Although the parents had lower ovalocyte percentage, degree of protection against malaria parasite was as effective as those found in patients with high ovalocytic red cells. This has been confirmed by statistical analysis showing nonsignificant difference in II value between the two groups. In contrast, red cells of both groups had poor deformability (deformability index, DI) as compared to the normal group. No statistically different DI values were demonstrated between the two. This indicates that poorly deformable red cells, not their ovalocytic shape, make a significant contribution to limitation of malaria parasite invasion. The MR values in patients were less than those found in the parent group but statistical analysis showed no significant difference. Reduced MR values were found with increased numbers of microcytic, hyperchromic and hypochromic red cells in patients.

Thalassemic serum inhibits endothelial cell mitosis in vitro

Human umbilical vein endothelial cells were cultured in vitro using Iscove's Modified Dulbecco's Medium (IMDM) supplemented with either pooled normal human serum, or pooled thalassemic serum, or autologous umbilical cord serum, or fetal bovine serum. The mitotic activity was determined under the inverted phase contrast microscope and the number of mitotic cells was counted. Our results showed that the mitotic cells decreased in endothelial cell culture with thalassemic serum as compared with normal human serum, autologous umbilical cord serum or fetal bovine serum. The percentage of mitotic cells decreased on day 3 in the presence of beta-thalassemia/HbE serum from both splenectomized and non-splenectomized patients as compared with normal or autologous umbilical cord serum. In the presence of alpha-thalassemic serum, a similar outcome was also observed. From this study we can conclude that the thalassemic sera might contain factors which affect the endothelial cell growth and proliferation by inhibiting mitosis in vitro.

Surface and total tissue factor activity of endothelial cells

With a technic that was developed by us, we found that normal human umbilical vein endothelial cells (HUVEC) in culture characteristically had very little tissue factor (TF) activity either on the surface or in the cells which had been disrupted. In the presence of endotoxin (E. coli O26:B6), a trigger for thrombosis in septicemic patients, we could not detect an increased TF activity of HUVEC on its surface. However, an increase in TF (total TF) was detected after disruption of the cells. The increase in total TF was dose-dependent. Endotoxin at the concentration of 10 micrograms/ml caused around 5 fold increase in total TF activity compared to that of HUVEC in the absence of endotoxin.

Possible evidence of endothelial cell activation and disturbance in thalassemia: an in vitro study

Activation of vascular endothelium is considered as an important facet of inflammation, thrombosis, and vasculitis. Activated endothelial cells express a number of immunologically relevant surface markers which are not detected in dormant condition. These surface markers on endothelial cell may involve in adhesion reaction and migration of blood cell components. We demonstrated increased level of the soluble adhesion molecules in circulating blood of both alpha- and beta-thalassemic patients. These adhesion molecules are theoretically known to be released from endothelial cells. The adhesion molecules included soluble Intercellular Adhesion Molecule-1 (sICAM-1), soluble E-Selectin (ELAM-1), soluble Vascular Cell Adhesion Molecule-1 (sVCAM-1), and von Willebrand Factor (vWF). The levels of these adhesion molecules were measured in serum from 32 thalassemic patients and 10 control healthy subjects. As compared to normal, increased sICAM-1 was found in beta-thal/HbE patients with non-splenectomy; BE-NS (p = 0.002), increased ELAM-1 in beta-thal/HbE patients with splenectomy; BE-S (p = 0.01) and HbH with Hb Constant Spring; HbH/CS (p = 0.001), and increased sVCAM-1 in BE-NS; (p = < 0.0001) and BE-S (p = 0.002). Significant increase in von Willebrand Factor (vWF), a marker for endothelial cell, was shown in BE-S (p = 0.04) as compared to normal. Adhesion molecules were also markedly demonstrated in the supernatant of in vitro culture of human vascular endothelial cell in the presence of 30% thalassemic serum, and these adhesion molecules were also detected on the surface of the cells by using the technic of laser scanning confocal microscope and direct immunofluorescence.

Alterations in vascular endothelial cell-related plasma proteins in thalassaemic patients and their correlation with clinical symptoms

An increased level of plasma thrombomodulin (TM) in alpha- and beta-thalassaemia was demonstrated using an enzyme-linked immunosorbent assay (ELISA). Nonsplenectomized patients with beta-thalassaemia/haemoglobin E (BE) had higher levels of TM than splenectomized cases (BE-S). Patients with leg ulcers (BE-LU) were found to have the highest increase in TM level. Appearance of larger platelets in all types of thalassaemic blood was observed indicating an increase in the number of younger platelets. These data indicate that injury of vascular endothelial cells is present in thalassaemic patients.

Cytometric analysis of blood cells from malaria-infected patients and in vitro infected blood

Blood samples from malaria-infected patients and from in vitro culture were analyzed using the H*1 hematology analyzer. An attempt to find a hematologic parameter for detecting the malaria infection and to characterize the pathophysiological changes of red cells was made. The study included 18 malaria-infected patients (10 with Plasmodium falciparum and 8 with Plasmodium vivax) and 52 normal, healthy volunteers. Increased young large lymphocyte or large unstained cell count (LUC over 3%) in the peripheral blood of malaria-infected patients was evidence for malaria infection. Increased population dispersions of red cell volume (red cell distribution width: RDW) and intraerythrocytic hemoglobin concentration (hemoglobin distribution width: HDW) were demonstrated both in clinical samples and cultured blood. The increased RDW correlated with an increased percentage of macrocytes (r = 0.64, P = 0.004). Comparison of HDW and percentage of hypochromic red cells between the clinical specimen and the cultured blood supports the finding that changes in red cell hemoglobin concentration were mainly due to the response of the patient to malaria infection and partly due to the effect of malaria parasites on the red cells.

Reduced deformability of thalassemic erythrocytes and erythrocytes with abnormal hemoglobins and relation with susceptibility to Plasmodium falciparum invasion

A number of genetically variant erythrocytes showed decreased deformability of both intact cells and membranes prepared therefrom as measured by laser diffractometry. Erythrocytes associated with minor or no clinical symptoms (eg, alpha-thalassemia traits, hemoglobin [Hb] E trait, Hb Constant Spring trait), which showed only a minimal decrease in deformability, were, in general, invaded efficiently by the malarial parasite Plasmodium falciparum. Other variant erythrocytes (beta-thalassemia/Hb E, homozygous Hb E, homozygous Hb Constant Spring, Hb H, Hb H/Hb Constant Spring) with low deformability showed different degrees of reduction in invasion susceptibility, most of which were less than proportional with deformability decrease. It is concluded that parasite invasion is only weakly related to gross cell deformability, which in turn depends on various factors other than membrane deformability.

Cytometric analysis of paroxysmal nocturnal hemoglobinuria erythrocytes

Erythrocytes from six cases of paroxysmal nocturnal hemoglobinuria (PNH) were analysed by the H*1 hematology analyser using laser inspection for each individual red cell. The computer program categorized the red cells into 9 groups based on the data of red cell volume and intracellular hemoglobin concentration. The only 46.3 +/- 10.9 per cent (Mean +/- SD) of PNH red cells were normochromic normocytic. Hypochromia (hemoglobin concentration less than 28 g/dL) with normal red cell volume (between 60 to 120 fL) were found in 22.8 +/- 19.7 per cent and with large cell volume (greater than 120 fL) = 14.9 +/- 4.5 per cent of total red cells. Large cells with normal hemoglobin concentration were found in 12.9 +/- 13.2 per cent. The red cells had increased heterogeneity in red cell volume measured as red cell distribution width (RDW), Mean +/- SD = 23.6 +/- 2.3 per cent and increased heterogeneity in their hemoglobin concentration distribution with (HDW) (3.4 +/- 0.5 g/dL). The high RDW was resulted from increased number of varying size of macrocytes and the high HDW was caused by the increased number of hypochromic red cells. Heterogeneity in PNH red cell population described in this study has been postulated to relate with the clonal abnormality of the PNH red cells.

An unusual adhesion between red-cells and platelets in falciparum malaria

A Thai female patient infected with P. falciparum had 80 per cent P. falciparum infected red cells at ring stage in the peripheral blood smear. The complications included anemia, thrombocytopenia, acute renal failure and pulmonary edema. A marked decrease in platelets number, low hemoglobin, low hematocrit and decreased red blood cell count were detected. More than 70 per cent of total platelets detected in the blood smear were binding to parasitized red blood cells. The number of binding platelets declined with decreasing per cent parasitized red cells. It was also noted that some platelets (10-20%) adhered to nonparasitized red cells. An increased number of large lymphocytes was shown by increased numbers of large unstained cells (LUC) by H* 1 automated analyzer. The peripheral blood smear showed abnormal binding of platelets to the infected red cells more frequently than to non infected red cells and free platelets on the day of high parasitemia. This abnormal phenomena was related to the number of platelets in the circulation. When the parasitized red cells were not detected in the blood smear, the number of platelets in the circulation had returned to normal.

Erythrocyte volume and haemoglobin concentration in haemoglobin H disease: discrimination between the two genotypes

Erythrocyte volume and haemoglobin concentration in individual red cells from 62 patients with Hb H disease: 37 with H genotype (alpha-thalassaemia 1/alpha-thalassaemia 2) and 25 H/CS genotype (alpha-thalassaemia 1/Hb Constant Spring) were measured using the H*1 haematology analyser. All 25 cases with H/CS genotype, the more severe genotype, had microcytes (red cells with a volume smaller than 60 fl) less than 35% and hypochromic red cells (red cells with haemoglobin concentration less than 28 g/dl) more than 35%. A discriminant function, the ratio between the percentage of hypochromic red cells and the percentage of microcytes (Hypo/Micro), was proposed. Most of the H/CS patients (76%) had Hypo/Micro greater than 2.5 whereas those of H patients (82%) were below 2.5. Red cell volume histograms were also characteristically different between the two genotypes: the H/CS had a peak between 60 and 90 fl while the H genotype showed a peak at or very close to 60 fl, indicating a greater degree of microcytosis. Increased hypochromia with a slight decrease in cell size of H/CS red cells suggests that the poor degree of haemoglobinization has no linkage or very little role in disturbing the synthesis of membrane proteins and their assembly to the plasma membrane.

Decreased sensitivity of artesunate and chloroquine of Plasmodium falciparum infecting hemoglobin H and/or hemoglobin constant spring erythrocytes

Plasmodium falciparum infecting hemoglobin (Hb) H and/or Hb Constant Spring erythrocytes in vitro was relatively more resistant than that infecting normal erythrocytes to artesunate and chloroquine, while the sensitivity to pyrimethamine was unchanged. The 50% inhibitory concentrations (IC50) for artesunate in HbH (alpha-thal 1/alpha-thal 2), HbH (alpha-thal 1/Hb Constant Spring), and homozygous Hb Constant Spring erythrocytes were 4.5 +/- 2.8, 8.5 +/- 3.2, and 2.6 +/- 1.6 nM compared with 0.82 +/- 0.35 nM in normal erythrocytes (P less than 0.002 for all three cases). The IC50 for chloroquine were 97 +/- 46, 162 +/- 67, and 93 +/- 36 nM, respectively, in the variant erythrocytes, compared with 48 +/- 13 nM in normal erythrocytes (P less than 0.002, 0.002, and 0.02, respectively). The differences in sensitivity to artesunate and chloroquine of the parasite infecting HbH erythrocytes are probably related to their oxidative mode of action and relatively high amounts of antioxidant enzymes in the host erythrocytes. This novel example of dependence on the host of the malarial parasite drug sensitivity may have implications for chemotherapy of malaria in patients with genetically variant erythrocytes.

Impaired parasite growth and increased susceptibility to phagocytosis of Plasmodium falciparum infected alpha-thalassemia or hemoglobin Constant Spring red blood cells

In vitro multiplication of Plasmodium falciparum in hemoglobin H or hemoglobin Constant Spring red blood cells (from homozygotes or double heterozygotes) was significantly reduced as compared with that in normal erythrocytes. The parasitized genetically abnormal red blood cells showed furthermore a high propensity for being phagocytosed by peripheral blood monocytes. Both impaired parasite growth and increased susceptibility to phagocytosis may be related to mechanisms for protection of the variants from P. falciparum infection.

Inhibitory effect of beta zero-thalassaemia/haemoglobin E erythrocytes on Plasmodium falciparum growth in vitro

The growth of Plasmodium falciparum in erythrocytes from individuals with beta zero-thalassaemia or haemoglobin (Hb) E, or both, was assessed in vitro. A significant inhibitory effect on the growth of the parasite was found only with erythrocytes from individuals doubly heterozygous for beta zeros-thalassaemia and HbE. The inhibitory effect was particularly marked with erythrocytes from splenectomized beta zeros-thalassaemia/HbE patients. The protective effect was related to HbF, Hb levels and shape abnormalities of the variant erythrocytes.

Increased phagocytosis of Plasmodium falciparum-infected erythrocytes with haemoglobin E by peripheral blood monocytes

Erythrocytes from subjects with homozygous and heterozygous haemoglobin E (HbE) infected with Plasmodium falciparum in vitro were phagocytosed to a greater extent by normal human monocytes than infected erythrocytes from normal subjects. Susceptibility to phagocytosis was maximal when the parasites developed to trophozoite and schizont stages in both normal and patients' erythrocytes. The increased susceptibility of P. falciparum-infected HbE erythrocytes to phagocytosis by monocytes may play a role in protection against malaria.