Dengue is the most significant arthropod borne viral disease worldwide, and infection with the dengue virus causes a wide range of symptoms in humans, including bone marrow suppression. While the target cells of the virus remain poorly characterized, cells of the myeloid lineage have been shown to be important mediators of the disease. This study sought to determine whether erythroid precursor cells were susceptible to dengue virus infection, and whether erythroid cells from thalassemia trait carriers showed any protection against infection. Infection with a laboratory adapted high passage DENV-2 resulted in high levels of infection during certain stages of differentiation, and cells derived from thalassemia trait carriers showed significantly reduced susceptibility to dengue virus infection. Infection with low passage isolates resulted in only scattered cells showing evidence of infection, but high bystander apoptosis that was reduced by both a caspase 8 inhibitor and anti-tumor necrosis factor 1 receptor antibodies.

The compound β°-thalassemia/Hb E hemoglobinopathy is characterized by an unusually large range of presentation from essentially asymptomatic to a severe transfusion dependent state. While a number of factors are known that moderate presentation, these factors do not account for the full spectrum of presentation. Mitochondria are subcellular organelles that are pivotal in a number of cellular processes including oxidative phosphorylation and apoptosis. A mitochondrial protein enriched proteome was determined and validated from erythroblasts from normal controls and β°-thalassemia/Hb E patients of different severities. Mitochondria were evaluated through the use of mitotracker staining, analysis of relative mitochondrial genome number and evaluation of mitochondrial gene expression in addition to assay of overall cellular redox status through the use of alamarBlue assays. Fifty differentially regulated mitochondrial proteins were identified. Mitotracker staining revealed significant differences in staining between normal control erythroblasts and those from β°-thalassemia/Hb E patients. Differences in relative mitochondria number and gene expression were seen primarily in day 10 cells. Significant differences were seen in redox status as evaluated by alamarBlue staining in newly isolated CD34+ cells. Mitochondria mediate oxidative phosphorylation and apoptosis, both of which are known to be dysregulated in differentiating erythrocytes from β°-thalassemia/Hb E patients. The evidence presented here suggest that there are inherent differences in these cells as early as the erythroid progenitor cell stage, and that maximum deficit is seen coincident with high levels of globin gene expression.

HbH and HbH-constant spring (HbH-CS) are the most common forms of α-thalassemia detected in the Thai population. The accumulation of excess β globin chains in these diseases results in increased red cell hemolysis, and patients with HbH-CS normally have a more severe clinical presentation than patients with HbH disease. This study aimed to detect alterations in the expression of plasma proteins of HbH and HbH-CS patients as compared to normal plasma. Platelet poor plasma was separated from HbH and HbH-CS and normal subjects and differential plasma proteins were detected using two-dimensional gel electrophoresis and identified using LC/MS/MS. A total of 14 differentially expressed proteins were detected of which 5 proteins were upregulated and 9 were downregulated. Most of the differentially expressed proteins are liver secreted proteins involved in hemolysis, oxidative stress response, and hemoglobin degradation. Seven proteins were found to be differentially expressed between HbH and HbH-CS. Levels of haptoglobin, a hemoglobin scavenging protein, were significantly increased in HbH patients as compared to HbH-CS patients. The identification of differentially expressed proteins may lead to a better understanding of the biological events underlying the clinical presentation of HbH and HbH-CS patients and can have application as hemolytic markers or severity predictors.

During erythropoiesis, iron levels need to be carefully regulated to ensure there is sufficient iron available for hemoglobin synthesis, but that there is no excess to cause damage to the developing erythroblast. Iron influx to the developing erythroblast is controlled by the expression of the transferrin receptor, while iron efflux is regulated by ferroportin (FPN), the sole iron-exporting protein. FPN is encoded through multiple messenger RNAs (mRNAs) some of which contain an iron-responsive element (variant I mRNAs) and some of which do not (variant II mRNAs). This study sought to investigate the expression of the FPN mRNAs in developing erythroblasts from normal controls and β(0)-thalassemia/Hb E patients. While levels of FPN protein were relatively constant, marked reductions of the variant I message were seen in erythroblasts from β(0)-thalassemia/Hb E patients as compared to normal control cells, particularly in late erythropoiesis. Variant II mRNAs were generally increased during erythroid differentiation. No difference was seen in levels of either transferrin or ferritin heavy chain expression. While no difference was observed in labile iron pools under normal culture conditions, erythroblasts from β(0)-thalassemia/Hb E patients showed a significantly reduced expression of total FPN message under high iron conditions as compared to normal control erythroblasts. These results are consisted with dysregulation of iron efflux from the maturing erythroblast in β(0)-thalassemia/Hb E patients, and this dysregulation possibly contributes to ineffective erythropoiesis seen in these patients.