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Immune deregulation has a critical role in the pathogenesis of lower risk myelodysplastic syndromes (MDS). The cells of the macrophage/monocyte lineage have been reported to contribute to the inflammatory process in MDS through impaired phagocytosis of the apoptotic hemopoietic cells and abnormal production of cytokines. In the present study we assessed the number of peripheral blood (PB) monocyte subsets, namely the classical CD14 bright /CD16 - , intermediate CD14 bright /CD16 + and non-classical CD14 dim /CD16 + cells, in patients with lower risk (low/intermediate-I) MDS (n = 32). We also assessed the production of tumor necrosis factor (TNF)α by patient PB monocytes in response to immune stimulus as well as their transcriptome profile. Compared to age- and sex-matched healthy individuals (n = 19), MDS patients had significantly lower number of classical and increased number of intermediate monocytes. Patient intermediate monocytes displayed increased production of TNFα following stimulation with lipopolysaccharide, compared to healthy individuals. Transcriptional profiling comparison of CD16 + monocytes from patients and controls revealed 43 differentially expressed genes mostly associated with biological pathways/processes relevant to hemopoiesis, immune signaling and cell adhesion. These data provide evidence for the first-time that distinct monocyte subsets display abnormal quantitative and functional characteristics in lower risk MDS substantiating their role in the immune deregulation associated with the disease., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Mounting evidence suggests that in myelodysplastic syndromes (MDSs) bone marrow (BM) mesenchymal stem/stromal cells (MSCs) possess abnormal characteristics and are actively involved in disease pathogenesis. Nevertheless, it is controversial whether these cells harbor clonal cytogenetic aberrations. To probe more deeply into this issue, in the present study we used conventional G-banding and FISH analysis to assess the clonal chromosomal abnormalities of hematopoietic cells (HCs) and cultured MSCs, from 29 MDS patients and 25 healthy individuals, at early, intermediate and late passage. Variable clonal cytogenetic aberrations were detected in HCs from 31% and in MSCs from 34% of MDS patients. Clonal chromosomal abnormalities in MSCs were detected even in patients without aberrations in HCs. They were mostly numerical and always differed from those in HCs from the same individual. Clonal chromosomal abnormalities did not seem to confer a proliferative and/or survival advantage to MSCs. HCs from normal donors harbored no cytogenetic abnormalities, whereas trisomy of chromosome 5 was detected in MSCs from 16% of healthy individuals, in line with other studies. Our results suggest that MDS-derived BM-MSCs are genetically unstable. The significance of this observation in the biology of MSCs and MDS pathogenesis is still unknown and warrants further evaluation., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Excessive pro-inflammatory cytokine production in the bone marrow has been associated with the pathogenesis of myelodysplastic syndromes. We herein investigated the involvement of toll-like receptors and their endogenous ligands in the induction/maintenance of the inflammatory process in the marrow of patients with myelodysplastic syndromes. We evaluated the expression of toll-like receptors in marrow monocytes of patients (n=27) and healthy controls (n=25) by flow-cytometry and also assessed the activation of the respective signaling using a real-time polymerase chain reaction-based array. We measured the high mobility group box-1 protein, a toll-like receptor-4 ligand, in marrow plasma and long-term bone marrow culture supernatants by an enzyme-linked immunosorbent assay and we performed cross-over experiments using marrow plasma from patients and controls in the presence/absence of a toll-like receptor-4 inhibitor to evaluate the pro-inflammatory cytokine production by chemiluminescence. We assessed the apoptotic cell clearance capacity of patients' macrophages using a fluorescence microscopy-based assay. We found over-expression of toll-like receptor-4 in patients' marrow monocytes compared to that in controls; this over-expression was associated with up-modulation of 53 genes related to the respective signaling. Incubation of patients' monocytes with autologous, but not with normal, marrow plasma resulted in over-production of pro-inflammatory cytokines, an effect that was abrogated by the toll-like receptor-4 inhibitor suggesting that the pro-inflammatory cytokine production in myelodysplastic syndromes is largely mediated through toll-like receptor-4. The levels of high mobility group box-1 protein were increased in patients' marrow plasma and culture supernatants compared to the levels in controls. Patients' macrophages displayed an impaired capacity to engulf apoptotic cells and this defect was associated with excessive release of high mobility group box-1 protein by dying cells. A primary apoptotic cell clearance defect of marrow macrophages in myelodysplastic syndromes may contribute to the induction/maintenance of the inflammatory process through aberrant release of molecules inducing toll-like receptor-4 such as high mobility group box-1 protein.

Eltrombopag is a nonpeptidyl thrombopoietin receptor agonist. We evaluated the ex vivo effect of eltrombopag on megakaryopoiesis of patients with lower risk myelodysplastic syndromes (MDSs). At a concentration of 0.1μg/mL, eltrombopag resulted in a significant increase in the number of megakaryocytic colonies in MDS patients and healthy controls compared to baseline. This dose of eltrombopag did not exert any significant change in the proliferation rate or the survival characteristics of patient CD34(+) cells that might clinically imply an unfavorable effect on patients' outcome. These encouraging preclinical data support the rationale of using eltrombopag in the clinic for alleviation of thrombocytopenia in lower risk MDS patients., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

Alterations of the ten-eleven translocation-2 (TET2) gene have been recently identified in patients with myeloid malignancies using molecular, comparative genomic hybridization and single nucleotide polymorphism array techniques. We have performed TET2 fluorescence in situ hybridization analysis in a cohort of patients with myeloid disorders including myeloid malignancies and chronic idiopathic neutropenia, aiming to determine the usefulness of the technique in the identification of TET2 gene alterations. A TET2 deletion was found in one patient with chronic myelomonocytic leukemia suggesting that fluorescence in situ hybridization may have a role in identification of TET2 deletions, at least in this group of patients., (Copyright © 2010 Elsevier Ltd. All rights reserved.)