CD20+ T cells in monoclonal B cell lymphocytosis and chronic lymphocytic leukemia: frequency, phenotype and association with disease progression.

Introduction: In monoclonal B cell lymphocytosis (MBL) and chronic lymphocytic leukemia (CLL), the expansion of malignant B cells disrupts the normal homeostasis and interactions between B cells and T cells, leading to immune dysregulation. CD20+ T cells are a subpopulation of T cells that appear to be involved in autoimmune diseases and cancer. Methods: Here, we quantified and phenotypically characterized CD20+ T cells from MBL subjects and CLL patients using flow cytometry and correlated our findings with the B-cell receptor mutational status and other features of the disease. Results and discussion: CD20+ T cells were more represented within the CD8+ T cell compartment and they showed a predominant memory Tc1 phenotype. CD20+ T cells were less represented in MBL and CLL patients vs healthy controls, particularly among those with unmutated IGVH gene. The expansion of malignant B cells was accompanied by phenotypic and functional changes in CD20+ T cells, including an increase in follicular helper CD4+ CD20+ T cells and CD20+ Tc1 cells, in addition to the expansion of the TCR Vß 5.1 in CD4+ CD20+ T cells in CLL.

Genetic Variants of ABC and SLC Transporter Genes and Chronic Myeloid Leukaemia: Impact on Susceptibility and Prognosis.

Solute carrier (SLC) and ATP-binding cassette (ABC) transporters comprise a variety of proteins expressed on cell membranes responsible for intrusion or extrusion of substrates, respectively, including nutrients, xenobiotics, and chemotherapeutic agents. These transporters mediate the cellular disposition of tyrosine kinase inhibitors (TKIs), and their genetic variants could affect its function, potentially predisposing patients to chronic myeloid leukaemia (CML) and modulating treatment response. We explored the impact of genetic variability (single nucleotide variants-SNVs) of drug transporter genes (ABCB1, ABCG2, SLC22A1, and SLC22A5) on CML susceptibility, drug response, and BCR-ABL1 mutation status. We genotyped 10 SNVs by tetra-primers-AMRS-PCR in 198 CML patients and 404 controls, and assessed their role in CML susceptibility and prognosis. We identified five SNVs associated with CML predisposition, with some variants increasing disease risk, including TT genotype ABCB1 (rs1045642), and others showing a protective effect (GG genotype SLC22A5 rs274558). We also observed different haplotypes and genotypic profiles associated with CML predisposition. Relating to drug response impact, we found that CML patients with the CC genotype (rs2231142 ABCG2) had an increased risk of TKI resistance (six-fold). Additionally, CML patients carrying the CG genotype (rs683369 SLC22A1) presented a 4.54-fold higher risk of BCR-ABL1 mutations. Our results suggest that drug transporters' SNVs might be involved in CML susceptibility and TKI response, and predict the risk of BCR-ABL1 mutations, highlighting the impact that SNVs could have in therapeutic selection.

Alterations in peripheral blood monocyte and dendritic cell subset homeostasis in relapsing-remitting multiple sclerosis patients.

Antigen-presenting cells participate and are implicated in the pathogenesis of multiple sclerosis. In our study we assessed the frequency of plasmacytoid (pDC) and myeloid (mDC) dendritic cells and the classical, intermediate and non-classical monocytes subsets, as well as their phenotypic and functional profile. We evaluated peripheral blood from relapsing-remitting patients treated with IFN-ß in remission and relapse phases and from healthy subjects. In remission, we observed a decrease of mDC/pDC ratio and a return to normal values in relapse. In both phases the frequency of non-classical monocytes decreases. Concerning the phenotypic characterization, an increased HLA-DR expression was observed in remission and a decrease in relapse, revealing alterations in monocytes and dendritic cells homeostasis.

Acute myeloid leukemia sensitivity to metabolic inhibitors: glycolysis showed to be a better therapeutic target.

Cancer cells alter their metabolism by switching from glycolysis to oxidative phosphorylation (OXPHOS), regardless of oxygen availability. Metabolism may be a molecular target in acute myeloid leukemia (AML), where mutations in metabolic genes have been described. This study evaluated glycolysis and OXPHOS as therapeutic targets. The sensitivity to 2-deoxy-D-glucose (2-DG; glycolysis inhibitor) and oligomycin (OXPHOS inhibitor) was tested in six AML cell lines (HEL, HL-60, K-562, KG-1, NB-4, THP-1). These cells were characterized for IDH1/2 exon 4 mutations, reactive oxygen species, and mitochondrial membrane potential. Metabolic activity was assessed by resazurin assay, whereas cell death and cell cycle were assessed by flow cytometry. Glucose uptake and metabolism-related gene expression were analyzed by 18F-FDG and RT-PCR/qPCR, respectively. No IDH1/2 exon 4 mutations were detected. HEL cells had the highest 18F-FDG uptake and peroxides/superoxide anion levels, whereas THP-1 showed the lowest. 2-DG reduced metabolic activity in all cell lines with HEL, KG-1, and NB-4 being the most sensitive cells. Oligomycin decreased metabolic activity in a cell line-dependent manner, the THP-1 resistant and HL-60 being the most sensitive. Both inhibitors induced apoptosis and cell cycle arrest in a cell line- and compound-dependent manner. 2-DG decreased 18F-FDG uptake in HEL, HL-60, KG-1, and NB-4, while oligomycin increased the uptake in K-562. Metabolism gene expression had different responses to treatments. In conclusion, HEL and KG-1 show to be more glycolytic, whereas HL-60 was more OXPHOS dependent. Results suggest that AML cells reprogram their metabolism to overcome OXPHOS inhibition suggesting that glycolysis may be a better therapeutic target.

Clearance and persistence of SARS-CoV-2 RNA in patients with COVID-19.

Patients with coronavirus disease-2019 may be discharged based on clinical resolution of symptoms, and evidence for viral RNA clearance from the upper respiratory tract. Understanding the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) viral clearance profile is crucial to establish a re-testing plan on discharge and ending isolation of patients. We aimed to evaluate the number of days that a patient needed to achieve undetectable levels of SARS-CoV-2 in upper respiratory tract specimens (nasopharyngeal swab and/or an oropharyngeal swab). The clearance and persistence of viral RNA was evaluated in two groups of positive patients: those who achieved two negative reverse transcription-polymerase chain reaction (RT-PCR) tests and those who kept testing positive. Patients were organized thereafter in two subgroups, mild illness patients discharged home and inpatients who had moderate to severe illness. Results from RT-PCR tests were then correlated with results from the evaluation of the immune response. The study evidenced that most patients tested positive for more than 2 weeks and that persistence of viral RNA is not necessarily associated with severe disease but may result from a weaker immune response instead.

Apoptosis induction and cell cycle arrest of pladienolide B in erythroleukemia cell lines.

Splicing of pre-mRNA into functional mRNA, carried out by the spliceosome, represents a crucial step in eukaryotic gene expression. Mutations and other deregulation in some of the spliceosome components have been identified in multiple pathologies, including hematological malignancies. In this context, we evaluated the therapeutic potential of a splicing inhibitor, Pladienolide B (Pla-B), in two erythroleukemia cell lines. HEL and K562 cell lines were incubated with increasing doses of Pla-B in single and daily administration. Cell viability and density were evaluated using trypan blue assay. Flow cytometry was used to evaluate cell death, cell cycle, and caspase activity. NGS analysis was performed to assess the mutational status of 4 splicing-related genes (SF3B1, U2AF1, ZRSR2 and SRSF2). Expression levels of SF3B1 and unspliced DNAJB1 were evaluated by qPCR. Pla-B significantly decreased the viability and proliferation of both cell lines in time, dose, administration schedule, and cell line-dependent manner. HEL cells were more sensible to Pla-B (IC50 = 1.5 nM) than K562 (IC50 = 25 nM), with an IC50 almost 17 times lower. Pla-B induced cell death, mainly by apoptosis, and cell cycle arrest in G0/G1 phase. No mutations were found in any of the analyzed genes, suggesting that the observed cytotoxic effect is independent of the spliceosome mutations. Splicing modulator Pla-B showed high antitumor activity against HEL and K562 cell lines, inducing apoptosis and cell cycle arrest. These data suggest that Pla-B might represent a new therapeutic approach for erythroleukemia.

International external quality assurance of JAK2 V617F quantification.

External quality assurance (EQA) programs are vital to ensure high quality and standardized results in molecular diagnostics. It is important that EQA for quantitative analysis takes into account the variation in methodology. Results cannot be expected to be more accurate than limits of the technology used, and it is essential to recognize factors causing substantial outlier results. The present study aimed to identify parameters of specific importance for JAK2 V617F quantification by quantitative PCR, using different starting materials, assays, and technical platforms. Sixteen samples were issued to participating laboratories in two EQA rounds. In the first round, 19 laboratories from 11 European countries analyzing JAK2 V617F as part of their routine diagnostics returned results from in-house assays. In the second round, 25 laboratories from 17 countries participated. Despite variations in starting material, assay set-up and instrumentation the laboratories were generally well aligned in the EQA program. However, EQA based on a single technology appears to be a valuable tool to achieve standardization of the quantification of JAK2 V617F allelic burden.

Identification of two novel mutations in RASGRP2 affecting platelet CalDAG-GEFI expression and function in patients with bleeding diathesis.

The RASGRP2 gene encodes the Ca2+ and DAG-regulated guanine nucleotide exchange factor I (CalDAG-GEFI), which plays a key role in integrin activation in platelets and neutrophils. We here report two new RASGRP2 variants associated with platelet dysfunction and bleeding in patients. The homozygous patients had normal platelet and neutrophil counts and morphology. Platelet phenotyping showed: prolonged PFA-100 closure times; normal expression of major glycoprotein receptors; severely reduced platelet aggregation response to ADP and collagen (both patients); aggregation response to PAR1 and arachidonic acid markedly impaired in one patient; PMA-induced aggregation unaffected; platelet secretion, clot retraction, and spreading minimally affected. Genetic analysis identified two new homozygous variants in RASGRP2: c.706C>T (p.Q236X) and c.887G>A (p.C296Y). In both patients, CalDAG-GEFI protein was not detectable in platelet lysates, and platelet αIIbß3 activation, as assessed by fibrinogen binding, was greatly impaired in response to all agonists except PMA. Patient neutrophils showed normal integrin expression, but impaired Mn2+-induced fibrinogen binding. In summary, we have identified two new RASGRP2 mutations that can be added to this rapidly growing form of inherited platelet function disorder.

Combined study of ADAMTS13 and complement genes in the diagnosis of thrombotic microangiopathies using next-generation sequencing.

BACKGROUND: The 2 main forms of thrombotic microangiopathy (TMA) are thrombotic thrombocytopenic purpura (TTP) and atypical hemolytic uremic syndrome (aHUS). Deficiency of ADAMTS13 and dysregulation of the complement pathway result in TTP and aHUS, respectively; however, overlap of their clinical characteristics makes differential diagnosis challenging. OBJECTIVES AND METHODS: We aimed to develop a TMA diagnosis workflow based on ADAMTS13 activity and screening of ADAMTS13 and complement genes using a custom next-generation sequencing (NGS) gene panel. PATIENTS: For this, from a cohort of 154 Portuguese patients with acute TMA, the genotype-phenotype correlations were analyzed in 7 hereditary TTP (ADAMTS13 activity <10%, no inhibitor), 36 acquired TTP (ADAMTS13 activity <10%, presence of an inhibitor), and in 34 presumable aHUS. RESULTS: In total, 37 different rare variants, 8 of which novel (in ADAMTS13,CFH, and CD46), were identified across 7 genes. Thirteen TTP patients were homozygous (n=6), compound heterozygous (n=2), and heterozygous (n=5) for 11 ADAMTS13 variants (6 pathogenic mutations). Among the 34 aHUS patients, 17 were heterozygous for 23 variants in the different complement genes with distinct consequences, ranging from single pathogenic mutations associated with complete disease penetrance to benign variants that cause aHUS only when combined with other variants and/or CFH and CD46 risk haplotypes or CFHR1-3 deletion. CONCLUSIONS: Our study provides evidence of the usefulness of the NGS panel as an excellent technology that enables more rapid diagnosis of TMA, and is a valuable asset in clinical practice to discriminate between TTP and aHUS.

JAK2V617F allele burden is associated with thrombotic mechanisms activation in polycythemia vera and essential thrombocythemia patients.

The clinical courses of polycythemia vera (PV) and essential thrombocythemia (ET) are characterized by thrombohemorrhagic diathesis. Several groups have suggested an association between JAK2V617F mutation and thrombosis. We hypothesized a relationship between JAK2V617F allele burden, cellular activation parameters, and thrombosis. We evaluated a group of PV and ET patients using flow cytometry: platelet CD62P, CD63, and dense granules, platelet-leukocyte aggregates (PLA), leukocyte CD11b and monocyte tissue factor (TF) expression. All patients had increased baseline platelet CD62P and CD63 expression (p < 0.05); 71 % of PV and 47 % of ET presented with a storage pool disease. Leukocyte CD11b, TF, and PLA were elevated in all patients. TF was higher in PV compared to ET (p < 0.05) and platelet-neutrophil [polymorphonuclear (PMN)] aggregates were increased in ET versus PV (p < 0.05). In ET, PLA were correlated with platelet numbers (p < 0.05). In all patients, JAK2V617F allele burden was directly correlated with monocyte CD11b. Patients with JAK2V617F allele burden >50 % presented higher levels of leukocyte activation. In ET, thrombosis was associated with JAK2V617F mutation (p < 0.05, χ (2) = 5.2), increased monocyte CD11b (p < 0.05) and with platelet-PMN aggregates (p < 0.05). In ET patients, hydroxyurea does not significantly reduce the activation parameters. Our data demonstrate that JAK2V617F allele burden is directly correlated with activation parameters that drive mechanisms that favor thrombosis.

Hb Iberia [α104(G11)Cys → Arg,TGC>CGC (α2) (HBA2:c.313T>C)], a new α-thalassemic hemoglobin variant found in the Iberian Peninsula: report of six cases.

We report a new structural defect of the α2-globin chain presenting with moderate microcytic hypochromic anemia, in six individuals from three unrelated families, living in Portugal and Spain. α-Globin gene deletions were ruled out by gap-polymerase chain reaction (gap-PCR) and multiplex ligation-dependent probe amplification (MLPA). Direct sequencing of the α2-globin gene revealed a substitution of codon 104 [α104(G11)Cys→Arg, TGC>CGC (α2) (HBA2:c.313T>C)]. This new variant, not detectable by high performance liquid chromatography (HPLC) or electrophoresis, was called Hb Iberia, as it was observed for the first time in families from the Iberian Peninsula. Although the mutant allele is transcribed, as indicated by the balanced mRNA α/ß ratio, the abnormal α2 chain could not form a stable tetramer as the cysteine and arginine residues, located at the α1ß1 contact, differ in size, charge and hydrophobicity. Hb Iberia is the third mutation described at codon 104 on the α-globin genes, namely, Hb Sallanches (α2, TGC>TAC) and Hb Oegstgeest (α1, TGC>AGC), also characterized as unstable hemoglobins (Hbs), present on an α-thalassemic phenotype.

Mutational spectrum of delta-globin gene in the Portuguese population.

The phenotype of increased Hb A2 typical of beta-thalassaemia (beta-thal) carriers can be reduced to normal or borderline values because of the co-inheritance of a delta-globin gene (HBD, MIM #142000) mutation, which may lead to misinterpretation of diagnostic results. To know the spectrum of delta-globin mutations in the Portuguese population we performed a mutational analysis of the delta-globin gene in a group of 51 Portuguese beta-thal carriers presenting microcytosis, hypochromia and a normal/borderline Hb A2 level and in another group of 15 individuals suspected to have delta-globin structural abnormalities. The heterozygosity for the beta(+)IVS-I-6T-->C (HBB:c. 92+6T>C) mutation was the main cause for the mentioned atypical beta-thal carrier phenotype. Furthermore, eight individuals were double heterozygous for one common beta-thal mutation and the delta(+)Cd27G-->T mutation (Hb A2-Yialousa; HBD:c.82G>T). One of them also presented a novel delta-globin gene promoter mutation,-80G-->A (HBD:c.-130G>A), responsible for about 25% decrease of the promoter activity in transient expression assays. One the other hand, in the other group of 15 individuals suspected to have delta-globin structural abnormalities observed by biochemical methods, some known Hb A2 variants were identified - Hb A2' (HBD:c.49G>C), Hb A2-Babinga (HBD:c.410G>A), and Hb A2-Wrens (HBD:c.295G>A), and the novel Hb A2-Fogo [delta64(E8)(Gly-->Ser); (HBD:c.193G>A)]. This novel Hb A2 variant was observed segregating in linkage with Hb E (HBB:c.79G>A) in a three generation family. In conclusion, six different delta-globin mutations were found, being two of them new molecular defects. All delta-alleles identified were found linked to the expected beta-globin cluster haplotype. All mutations caused a low Hb A2 level and through this could lead to misdiagnosis when inherited together with a beta-thal allele.