Project description:We hypothesized that miRNA regulation may be invloved in hydroxyurea-mediated fetal hemoglobin induction. Microarray analysis was utilized as an initial screening tool to determine differential miRNA expression in CD71+ erythroid cells comparing cells from control individuals without sickle cell anemia to patients with sickle cell anemia prior to treatment with hydroxyurea and patients receiving the maximum tolerated dose (MTD) of hydroxurea. CD71+ cells were isolated from whole blood of control individuals (n=2), pediatric patients without hydroxyurea treatment (n=3) and pediatric patients at hydroxyurea MTD (n=3). All 8 samples were analyzed for miRNA expression.
Project description:We hypothesized that miRNA regulation may be invloved in hydroxyurea-mediated fetal hemoglobin induction. Microarray analysis was utilized as an initial screening tool to determine differential miRNA expression in CD71+ erythroid cells comparing cells from control individuals without sickle cell anemia to patients with sickle cell anemia prior to treatment with hydroxyurea and patients receiving the maximum tolerated dose (MTD) of hydroxurea.
Project description:Genetic differences in endothelial biology could underlie development of phenotypic heterogeneity amongst individuals afflicted with vascular diseases. We obtained BOEC (blood outgrowth endothelial cells) from 20 subjects with sickle cell anemia (age 4-19) shown to be either at-risk (n=11) or not-at-risk (n=9) for ischemic stroke due to, respectively, having or not having occlusive disease at the Circle of Willis (CoW). Gene expression profiling identified no significant single gene differences between the two groups, as expected. However, analysis of Biological Systems Scores, using gene sets that were pre-determined to survey each of nine biological systems, showed that only changes in inflammation signaling are characteristic of the at-risk subjects, as supported by multiple statistical approaches Experiment Overall Design: We obtained BOEC (blood outgrowth endothelial cells) from 20 subjects with sickle cell anemia (age 4-19) shown to be either at-risk (n=11) or not-at-risk (n=9) for ischemic stroke due to, respectively, having or not having occlusive disease at the Circle of Willis (CoW). To allow power calculations to be done, we performed microarray analysis on BOEC from 27 normal subjects of diverse ages. Gene expression profilings were obtained by using Affymetrix U133A chips
Project description:To analyze expression of inflammatory cytokines in Exhaled Breath Condensates from pediatric patients with sickle cell disease, asthma, sickle cell disease and asthma, and controls
Project description:Transcriptional changes in compensatory erythropoiesis in sickle cell anemia (SCA) and their disease modulation are unclear. We detected 1226 differentially expressed genes in hemoglobin SS reticulocytes compared to non-anemic hemoglobin AA controls. Assessing developmental expression changes in hemoglobin AA erythroblasts for these genes suggests heightened terminal differentiation in early erythroblasts in SCA that diminishes toward the polychromatic to orthochromatic stage transition. Comparison of reticulocyte gene expression changes in SCA with that in Chuvash erythrocytosis, a non-anemic disorder of increased erythropoiesis due to constitutive activation of hypoxia inducible factors, identified 453 SCA-specific changes attributable to compensatory erythropoiesis. Peripheral blood mononuclear cells (PBMCs) in SCA contain elevated proportions of erythroid progenitors due to heightened erythropoiesis. Deconvolution analysis in PBMCs from 131 SCA patients detected 54 genes whose erythroid expression correlated with erythropoiesis efficiency, which were enriched with SCA-specific changes (OR=2.9, P=0.00063) and annotation keywords of “ubiquitin-dependent protein catabolic process” and “protein ubiquitination” (OR=4.1, P=9.6×10-5). An erythroid expression quantitative trait locus of one of these genes, LNX2 encoding an E3 ubiquitin ligase, associated with severe pain episodes in 774 SCA patients (OR=1.7, P=3.9×10-5). Thus, erythroid gene transcription responds to unique conditions within SCA erythroblasts and these changes potentially correspond to vaso-occlusive manifestations.
Project description:Ischemic Stroke (IS) is one of the most impairing complications of sickle cell anemia (SCA), responsible for 20% of mortality in patients. Rheological alterations, adhesive properties of sickle reticulocytes, leukocyte adhesion, inflammation and endothelial dysfunction are related to the vasculopathy observed prior to ischemic events. The role of the vascular endothelium in this complex cascade of mechanisms is emphasized, as well as in the process of ischemia-induced repair and neovascularization. The aim of the present study was to perform a comparative transcriptomic analysis of endothelial colony-forming cells (ECFCs) from SCA patients with and without IS. Next, to gain further insights of the biological relevance of differentially expressed genes (DEGs), functional enrichment analysis, protein-protein interaction network (PPI) construction and in silico prediction of regulatory factors were performed. Among the 2,469 DEGs, genes related to cell proliferation (AKT1, E2F1, CDCA5, EGFL7), migration (AKT1, HRAS), angiogenesis (AKT1, EGFL7) and defense response pathways (HRAS, IRF3, TGFB1), important endothelial cell molecular mechanisms in post ischemia repair were identified. Despite the severity of IS in SCA, widely accepted molecular targets are still lacking, especially related to stroke outcome. Thus, these exploratory results may contribute to a better understanding of the role of endothelial cells in SCA ischemic stroke recovery, and promote new insights to further studies on therapeutic strategies for this severe complication.
Project description:Compromised renal function after renal allograft transplantation often results in anemia in the recipient. Molecular mechanisms leading to anemia during acute rejection are not fully understood; inadequate erythropoietin production and iron deficiency have been reported to be the main contributors. To increase our understanding of the molecular events underlying anemia in acute rejection, we analyzed the gene expression profiles of peripheral blood lymphocytes (PBL) from four pediatric renal allograft recipients with acute rejection and concurrent anemia, using DNA microarrays containing 9000 human cDNA clones (representing 7469 unique genes). In these anemic rejecting patients, an 'erythropoiesis cluster' of 11 down-regulated genes was identified, involved in hemoglobin transcription and synthesis, iron and folate binding and transport. Additionally, some alloimmune response genes were simultaneously down-regulated. An independent data set of 36 PBL samples, some with acute rejection and some with concurrence of acute rejection and anemia, were analyzed to support a possible association between acute rejection and anemia. In conclusion, analysis using DNA microarrays has identified a cluster of genes related to hemoglobin synthesis and/or erythropoeisis that was altered in kidneys with renal allograft rejection compared with normal kidneys. The possible relationship between alterations in the expression of this cluster, reduced renal function, the alloimmune process itself, and other influences on the renal transplant awaits further analysis.
Project description:<p>Phenotypic heterogeneity is characteristic of sickle cell anemia, a Mendelian disorder caused by homozygosity for the sickle HBB gene (glu6val). Patients have different rates of hemolysis/vasculopathy and viscosity/vasoocclusion-related complications. These complications account for a substantial reduction in life expectancy. In 1994, the median life expectancy for men and women with sickle cell anemia was 42 and 48 years, respectively, and despite many advances in care, the annual mortality still approaches 4%. Fetal hemoglobin (HbF) is one of the most studied markers of severity of sickle cell anemia, and detailed longitudinal measurements were taken on subjects enrolled in the Cooperative Study of Sickle Cell Disease (CSSCD). Cubic root transformation of the median values from follow-up in 848 African American subjects is the phenotype data used in the GWAS of fetal hemoglobin. The analysis was adjusted by sex. Details are in Solovieff et al., Blood 2010 [PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/20018918" target="_blank">20018918</a>].</p> <p>To integrate individual disease complications into a comprehensive measure of severity, we developed a model of the associations among clinical and laboratory variables that scored disease severity as the risk of death within 5 years. This network was developed using data obtained from more than 3,400 subjects from the CSSCD, and its accuracy was validated in two unrelated sets of sickle cell patients. Recently, the network was also validated in a small European cohort of patients with sickle cell anemia. We used extreme values of disease severity as cases and control in the GWAS of severity of sickle cell anemia. We conducted the GWAS in 1,265 patients with either "severe" (177) or "mild" disease (1088) based on a network model of disease severity. Details are in Sebastiani et al. Am J Hematol, 2010 [PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/20029952" target="_blank">20029952</a>].</p>
Project description:Room temperature whole blood mRNA stabilization procedures, such as the PAX gene system, are critical for the application of transcriptional analysis to population-based clinical studies. Global transcriptome analysis of whole blood RNA using microarrays has proven to be challenging due to the high abundance of globin transcripts that constitute 70% of whole blood mRNA in the blood. This is a particular problem in patients with sickle-cell disease, secondary to the high abundance of globin-expressing nucleated red blood cells and reticulocytes in the circulation . In order to more accurately measure the steady state whole blood transcriptome in sickle-cell patients, we evaluated the efficacy of reducing globin transcripts in PAXgene stabilized RNA samples for genome-wide transcriptome analyses using oligonucleotide arrays. We demonstrate here by both microarrays and Q-PCR that the globin mRNA depletion method resulted in 55-65 fold reduction in globin transcripts in whole blood collected from healthy volunteers and sickle-cell disease patients. This led to an improvement in microarray data quality with increased detection rate of expressed genes and improved overlap with the expression signatures of isolated peripheral blood mononuclear (PBMC) preparations. The differentially modulated genes from the globin depleted samples had a higher correlation coefficient to the 112 genes identified to be significantly altered in our previous study on sickle-cell disease using PBMC preparations. Additionally, the analysis of differences between the whole blood transcriptome and PBMC transcriptome reveals important erythrocyte genes that participate in sickle-cell pathogenesis and compensation. The combination of globin mRNA reduction after whole-blood RNA stabilization represents a robust clinical research methodology for the discovery of biomarkers for hematologic diseases and in multicenter clinical trials investigating a wide range of nonhematologic disorders where fractionation of cell types is impracticable. Keywords: Microarrays, PAXgene, globin reduction, whole blood, PBMC There are 10 samples for each of PBMC, PAX and PAX globin-reduced, where 5 samples come from sickle-cell patients and 5 from healthy controls.