Comparative transcriptomic analysis of circulating endothelial cells in sickle cell stroke

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 2469 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. The comparative analysis of the gene expression profile of ECFCs from IS patients versus controls seems to indicate that there is a persistent angiogenic process even after a long time this complication has occurred. Thus, this is an original study which may lead to new insights into the molecular basis of SCA stroke and contribute to a better understanding of the role of endothelial cells in stroke recovery.

Comparative transcriptome analysis of endothelial progenitor cells of HbSS patients with and without proliferative retinopathy

Among sickle cell anemia (SCA) complications, proliferative sickle cell retinopathy (PSCR) is one of the most important, being responsible for visual impairment in 10-20% of affected eyes. The aim of this study was to identify differentially expressed genes (DEGs) present in pathways that may be implicated in the pathophysiology of PSCR from the transcriptome profile analysis of endothelial progenitor cells. RNA-Seq was used to compare gene expression profile of circulating endothelial colony-forming cells (ECFCs) from HbSS patients with and without PSCR. Furthermore, functional enrichment analysis and protein-protein interaction (PPI) networks were performed to gain further insights into biological functions. The differential expression analysis identified 501 DEGs, when comparing the groups with and without PSCR. Furthermore, functional enrichment analysis showed associations of the DEGs in 200 biological processes. Among these, regulation of mitogen-activated protein (MAP) kinase activity, positive regulation of phosphatidylinositol 3-kinase (PI3K), and positive regulation of Signal Transducer and Activator of Transcription (STAT) receptor signaling pathway were observed. These pathways are associated with angiogenesis, cell migration, adhesion, differentiation, and proliferation, important processes involved in PSCR pathophysiology. Moreover, our results showed an over-expression of VEGFC (vascular endothelial growth factor-C) and FLT1 (Fms-Related Receptor Tyrosine Kinase 1) genes, when comparing HbSS patients with and without PSCR. These results may indicate a possible association between VEGFC and FLT1 receptor, which may activate signaling pathways such as PI3K/AKT and MAPK/ERK and contribute to the mechanisms implicated in neovascularization. Thus, our findings contain preliminary results that may guide future studies in the field, since the molecular mechanisms of PSCR are still poorly understood.

Phenotypes of STAT3 gain-of-function variant related to disruptive regulation of CXCL8/STAT3, KIT/STAT3, and IL-2/CD25/Treg axes

STAT3 is a cytokine-signaling transcription factor critical for gene regulation. Gain-of-function (GOF) mutations in STAT3 are associated with lymphoproliferation, autoimmune cytopenias, increased susceptibility to infection, early-onset solid-organ autoimmunity, short stature, and eczema. We studied the JAK/STAT signaling pathway gene expression and the cytokine profile in two families carrying STAT3-GOF variants to shed light on the STAT3-GOF-associated variable expressivity, including the identification of disease markers. Considering 92 target genes, KIT and IL2RA were downregulated only in patients with high clinical penetrance, while CXCL8 was markedly downregulated for all of them. Unlike previous studies, SOCS3-a STAT3 inhibitor-was not upregulated in patients. In addition, low levels of IL-2 and a reduced numbers of Tregs cells were strikingly prevalent in patients. This study shows a disruptive role of STAT3-GOF variants in the regulatory axis activities CXCL8/STAT3, KIT/STAT3, IL2/CD25/Treg, which, by slightly different mechanisms, underlie the broad clinical spectrum seen in the studied patients. In addition, we suggest the investigation of CXCL8 as a biomarker for identifying STAT3-GOF mutation.

Inflammatory Dendritic Cells Contribute to Regulate the Immune Response in Sickle Cell Disease

Sickle cell disease (SCD), one of the most common hemoglobinopathies worldwide, is characterized by a chronic inflammatory component, with systemic release of inflammatory cytokines, due to hemolysis and vaso-occlusive processes. Patients with SCD demonstrate dysfunctional T and B lymphocyte responses, and they are more susceptible to infection. Although dendritic cells (DCs) are the main component responsible for activating and polarizing lymphocytic function, and are able to produce pro-inflammatory cytokines found in the serum of patients with SCD, minimal studies have thus far been devoted to these cells. In the present study, we identified the subpopulations of circulating DCs in patients with SCD, and found that the bloodstream of the patients showed higher numbers and percentages of DCs than that of healthy individuals. Among all the main DCs subsets, inflammatory DCs (CD14⁺ DCs) were responsible for this rise and correlated with higher reticulocyte count. The patients had more activated monocyte-derived DCs (mo-DCs), which produced MCP-1, IL-6, and IL-8 in culture. We found that a CD14⁺ mo-DC subset present in culture from some of the patients was the more activated subset and was mainly responsible for cytokine production, and this subset was also responsible for IL-17 production in co-culture with T lymphocytes. Finally, we suggest an involvement of heme oxygenase in the upregulation of CD14 in mo-DCs from the patients, indicating a potential mechanism for inducing inflammatory DC differentiation from circulating monocytes in the patients, which correlated with inflammatory cytokine production, T lymphocyte response skewing, and reticulocyte count.

Genetic and Clinical Heterogeneity in Thirteen New Cases with Aceruloplasminemia. Atypical Anemia as a Clue for an Early Diagnosis

Aceruloplasminemia is a rare autosomal recessive genetic disease characterized by mild microcytic anemia, diabetes, retinopathy, liver disease, and progressive neurological symptoms due to iron accumulation in pancreas, retina, liver, and brain. The disease is caused by mutations in the Ceruloplasmin (CP) gene that produce a strong reduction or absence of ceruloplasmin ferroxidase activity, leading to an impairment of iron metabolism. Most patients described so far are from Japan. Prompt diagnosis and therapy are crucial to prevent neurological complications since, once established, they are usually irreversible. Here, we describe the largest series of non-Japanese patients with aceruloplasminemia published so far, including 13 individuals from 11 families carrying 13 mutations in the CP gene (7 missense, 3 frameshifts, and 3 splicing mutations), 10 of which are novel. All missense mutations were studied by computational modeling. Clinical manifestations were heterogeneous, but anemia, often but not necessarily microcytic, was frequently the earliest one. This study confirms the clinical and genetic heterogeneity of aceruloplasminemia, a disease expected to be increasingly diagnosed in the Next-Generation Sequencing (NGS) era. Unexplained anemia with low transferrin saturation and high ferritin levels without inflammation should prompt the suspicion of aceruloplasminemia, which can be easily confirmed by low serum ceruloplasmin levels. Collaborative joint efforts are needed to better understand the pathophysiology of this potentially disabling disease.

Treatment with dasatinib or nilotinib in chronic myeloid leukemia patients who failed to respond to two previously administered tyrosine kinase inhibitors--a single center experience

OBJECTIVE

To evaluate hematological, cytogenetic and molecular responses as well as the overall, progression-free and event-free survivals of chronic myeloid leukemia patients treated with a third tyrosine kinase inhibitor after failing to respond to imatinib and nilotinib/dasatinib.

METHODS

Bone marrow karyotyping and real-time quantitative polymerase chain reaction were performed at baseline and at 3, 6, 12 and 18 months after the initiation of treatment with a third tyrosine kinase inhibitor. Hematologic, cytogenetic and molecular responses were defined according to the European LeukemiaNet recommendations. BCR-ABL1 mutations were analyzed by Sanger sequencing.

RESULTS

We evaluated 25 chronic myeloid leukemia patients who had been previously treated with imatinib and a second tyrosine kinase inhibitor. Nine patients were switched to dasatinib, and 16 patients were switched to nilotinib as a third-line therapy. Of the chronic phase patients (n=18), 89% achieved a complete hematologic response, 13% achieved a complete cytogenetic response and 24% achieved a major molecular response. The following BCR-ABL1 mutations were detected in 6/14 (43%) chronic phase patients: E255V, Y253H, M244V, F317L (2) and F359V. M351T mutation was found in one patient in the accelerated phase of the disease. The five-year overall, progression-free and event-free survivals were 86, 54 and 22% (p<0.0001), respectively, for chronic phase patients and 66%, 66% and 0% (p<0.0001), respectively, for accelerated phase patients. All blast crisis patients died within 6 months of treatment. Fifty-six percent of the chronic phase patients lost their hematologic response within a median of 23 months.

CONCLUSIONS

Although the responses achieved by the third tyrosine kinase inhibitor were not sustainable, a third tyrosine kinase inhibitor may be an option for improving patient status until a donor becomes available for transplant. Because the long-term outcome for these patients is poor, the development of new therapies for resistant chronic myeloid leukemia patients is necessary.

Erythropoiesis-driven regulation of hepcidin in human red cell disorders is better reflected through concentrations of soluble transferrin receptor rather than growth differentiation factor 15

Growth differentiation factor 15 (GDF-15) is a bone marrow-derived cytokine whose ability to suppress iron regulator hepcidin in vitro and increased concentrations found in patients with ineffective erythropoiesis (IE)suggest that hepcidin deficiency mediated by GDF-15 may be the pathophysiological explanation for nontransfusional iron overload. We aimed to compare GDF-15 production in anemic states with different types of erythropoietic dysfunction. Complete blood counts, biochemical markers of iron status, plasma hepcidin, GDF-15, and known hepcidin regulators [interleukin-6 and erythropoietin (EPO)] were measured in 87 patients with red cell disorders comprising IE and hemolytic states: thalassemia, sickle cell anemia, and cobalamin deficiency. Healthy volunteers were also evaluated for comparison. Neither overall increased EPO,nor variable GDF-15 concentrations correlated with circulating hepcidin concentrations (P = 0.265 and P = 0.872). Relative hepcidin deficiency was found in disorders presenting with concurrent elevation of GDF-15 and soluble transferrin receptor (sTfR), a biomarker of erythropoiesis, and sTfR had the strongest correlation with hepcidin (r(s) = 0.584, P < 0.0001). Our data show that high concentrations of GDF-15 in vivo are not necessarily associated with pathological hepcidin reduction, and hepcidin deficiency was only found when associated with sTfR overproduction. sTfR elevation may be a necessary common denominator of erythropoiesis-driven mechanisms to favor iron absorption in anemic states and appears a suitable target for investigative approaches to iron disorders.

JAK2 V617F mutation prevalence in myeloproliferative neoplasms in Pernambuco, Brazil

BACKGROUND

The JAK2 V617F mutation is associated with three myeloproliferative neoplasms (MPNs): polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF). It generates an unregulated clonal hematopoietic progenitor and leads to abnormal increased proliferation of one or more myeloid lineages. Subjects bearing this mutation may present more frequently with complications such as thrombosis and bleeding, and no specific treatment has yet been developed for BCR-ABL-negative JAK2 V617F-negative MPNs.

AIMS

To determine the prevalence of JAK2 V617F in MPNs in Pernambuco, Brazil, and to compare it with previous studies.

MATERIAL AND METHODS

144 blood samples were collected at the Hospital of Hematology of the HEMOPE Foundation and were genotyped by polymerase chain reaction-restriction fragment length polymorphism with BsaXI enzymatic digestion.

RESULTS AND DISCUSSION

88% (46/52) of the patients with PV, 47% (39/81) with ET, and 77% (8/11) with PMF were positive for JAK2 V617F, while more than 35% of the individuals were JAK2 V617F-negative, confirming a high prevalence of this abnormality in MPNs, more frequently with a low mutated allele burden, similar to what has been reported in other Western countries, despite differences among methods used to detect this mutation. Screening for JAK2 V617F may allow specific management of these diseases with JAK2 inhibitors in the future and highlights the need for further studies on the pathogenesis of BCR-ABL-negative JAK2 V617F-negative MPNs.

Trypanosoma cruzi: parasite persistence in tissues in chronic chagasic Brazilian patients

Chagas disease in the chronic phase may develop into cardiac and/or digestive forms. The pathogenesis of the disease is not yet clear and studies have been carried out to elucidate the role of parasite persistence in affected organs. The aim of this study was to detect and quantify Trypanosoma cruzi in paraffin-embedded tissue samples from chronic patients using NPCR (nested polymerase chain reaction) and QPCR (quantitative polymerase chain reaction) methods. These results were correlated to anatomopathological alterations in the heart and gastrointestinal tract (GIT). Of the 23 patients studied, 18 presented the cardiac form and five presented the cardiodigestive form of Chagas disease. DNA samples were randomly isolated from formalin-fixed paraffin-embedded sections of heart and GIT tissue of 23 necropsies and were analyzed through NPCR amplification. T. cruzi DNA was detected by NPCR in 48/56 (85.7%) heart and 35/42 (83.3%) GIT samples from patients with the cardiac form. For patients with the cardiodigestive form, NPCR was positive in 12/14 (85.7%) heart and in 14/14 (100%) GIT samples. QPCR, with an efficiency of 97.6%, was performed in 13 samples (11 from cardiac and 2 from cardiodigestive form) identified previously as positive by NPCR. The number of T. cruzi copies was compared to heart weight and no statistical significance was observed. Additionally, we compared the number of copies in different tissues (both heart and GIT) in six samples from the cardiac form and two samples from the cardiodigestive form. The parasite load observed was proportionally higher in heart tissues from patients with the cardiac form. These results show that the presence of the parasite in tissues is essential to Chagas disease pathogenesis.

Gene expression profiles of erythroid precursors characterise several mechanisms of the action of hydroxycarbamide in sickle cell anaemia

Hydroxycarbamide (HC) (or hydroxyurea) has been reported to increase fetal haemoglobin levels and improve clinical symptoms in sickle cell anaemia (SCA) patients. However, the complete pathway by which HC acts remains unclear. To study the mechanisms involved in the action of HC, global gene expression profiles were obtained from the bone marrow cells of a SCA patient before and after HC treatment using serial analysis of gene expression. In the comparison of both profiles, 147 differentially expressed transcripts were identified. The functional classification of these transcripts revealed a group of gene categories associated with transcriptional and translational regulation, e.g. EGR-1, CENTB1, ARHGAP4 and RIN3, suggesting a possible role for these pathways in the improvement of clinical symptoms of SCA patients. The genes involved in these mechanisms may represent potential tools for the identification of new targets for SCA therapy.

Use of a nested polymerase chain reaction (N-PCR) to detect Trypanosoma cruzi in blood samples from chronic chagasic patients and patients with doubtful serologies

Chagas disease, caused by Trypanosoma cruzi, is an important endemic illness in Latin America. Serologic tests for T. cruzi detection in blood are sensitive, but their specificity is unsatisfactory. Direct detection of parasites in blood, either by xenodiagnosis or hemoculture, is highly specific but of low sensitivity. Molecular assays such as the Polymerase chain reaction (PCR), which amplifies certain repetitive sequences of nuclear DNA has been used as a good alternative tool for T. cruzi detection in human blood. The present study aimed to test PCR diagnosis in chagasic chronic patients and doubtful serologic patients attended in GEDOCH (Chagas Disease Study Group/UNICAMP, Brazil). A 149 bp fragment originated from nuclear DNA was specifically detected in chronic chagasic patients. The results of these tests were compared with serologic diagnosis performed using standard techniques and xenodiagnosis. We found that 43 out of 50 patients previously serodiagnosed as chagasic were positive using the N-PCR method. Thirteen of 30 patients with doubtful serologic results were confirmed as positive by N-PCR. Our results suggest that the N-PCR may be a complementary tool to serology in the diagnosis of Chagas disease, and that it is usefull for parasite detection in patients with chronic disease and patients with doubtful serologic results.