Search

Background In ineffective erythropoiesis, hepcidin synthesis is suppressed by erythroid regulators, namely erythroferrone and growth differentiation factor-15. For the first time, the hypothesis that iron overload in megaloblastic anemia may be related to ineffective erythropoiesis is explored by describing the kinetics of hepcidin, erythroferrone, and growth differentiation factor-15 levels in a patient diagnosed with megaloblastic anemia associated with iron overload. Case presentation An 81-year-old Caucasian male was admitted for fatigue. He had type-2 diabetes previously treated with metformin, ischemic cardiac insufficiency, and stage-3 chronic kidney disease. Vitiligo was observed on both hands. Biological tests revealed normocytic non-regenerative anemia associated with hemolysis, thrombocytopenia, and elevated sideremia, ferritin, and transferrin saturation levels. Megaloblastic anemia was confirmed with undetectable blood vitamin B12 and typical cytological findings like hyper-segmented neutrophils in blood and megaloblasts in bone marrow. The patient received vitamin B12 supplementation. At 3 months, biological parameters reached normal values. Hepcidin kinetics from diagnosis to 3 months inversely correlated with those of erythroferrone and growth differentiation factor-15. Conclusions This case suggests that iron-overload mechanisms of dyserythropoietic anemias may apply to megaloblastic anemias.

Simple Summary Pesticide exposure is a public health concern. Two recent studies reported that exposure of normal primary bone marrow mesenchymal stem/stromal cells (BM-MSCs) to low-dose pesticide mixture induces deleterious consequences, such as oxidative stress, senescence, accelerated aging and increased sensitivity to oncogenic hits. Here, we show that exposure to this mixture decreases aldehyde dehydrogenase-2 (ALDH2) activity, with a concomitant increase in acetaldehyde level and DNA damage and alters the MSC capacity to support primitive hematopoiesis. Similar abnormalities were observed in bone marrow-MSCs from patients suffering from myelodysplastic syndrome (MDS), suggesting a role of pesticide-induced ALDH2 inhibition in the pathophysiology of this pre-leukemic disease. Abstract (1) Background: The impact of occupational exposure to high doses of pesticides on hematologic disorders is widely studied. Yet, lifelong exposure to low doses of pesticides, and more particularly their cocktail effect, although poorly known, could also participate to the development of such hematological diseases as myelodysplastic syndrome (MDS) in elderly patients. (2) Methods: In this study, a cocktail of seven pesticides frequently present in water and food (maneb, mancozeb, iprodione, imazalil, chlorpyrifos ethyl, diazinon and dimethoate), as determined by the European Food Safety Authority, were selected. Their in vitro effects at low-doses on primary BM-MSCs from healthy volunteers were examined. (3) Results: Exposure of normal BM-MSCs to pesticides for 21 days inhibited cell proliferation and promoted DNA damage and senescence. Concomitantly, these cells presented a decrease in aldehyde dehydrogenase 2 (ALDH2: mRNA, protein and enzymatic activity) and an increase in acetaldehyde levels. Pharmacological inhibition of ALDH2 with disulfiram recapitulated the alterations induced by exposure to low doses of pesticides. Moreover, BM-MSCs capacity to support primitive hematopoiesis was significantly altered. Similar biological abnormalities were found in primary BM-MSCs derived from MDS patients. (4) Conclusions: these results suggest that ALDH2 could participate in the pathophysiology of MDS in elderly people long exposed to low doses of pesticides.

The bone marrow (BM) niche impacts the progression of acute myeloid leukemia (AML) by favoring the chemoresistance of AML cells. Intimate interactions between leukemic cells and BM mesenchymal stromal cells (BM-MSCs) play key roles in this process. Direct intercellular communications between hematopoietic cells and BM-MSCs involve connexins, components of gap junctions. We postulated that blocking gap junction assembly could modify cell–cell interactions in the leukemic niche and consequently the chemoresistance. The comparison of BM-MSCs from AML patients and healthy donors revealed a specific profile of connexins in BM-MSCs of the leukemic niche and the effects of carbenoxolone (CBX), a gap junction disruptor, were evaluated on AML cells. CBX presents an antileukemic effect without affecting normal BM-CD34+ progenitor cells. The proapoptotic effect of CBX on AML cells is in line with the extinction of energy metabolism. CBX acts synergistically with cytarabine (Ara-C) in vitro and in vivo. Coculture experiments of AML cells with BM-MSCs revealed that CBX neutralizes the protective effect of the niche against the Ara-C-induced apoptosis of leukemic cells. Altogether, these results suggest that CBX could be of therapeutic interest to reduce the chemoresistance favored by the leukemic niche, by targeting gap junctions, without affecting normal hematopoiesis.

INTRODUCTION Cytokines are involved in many processes, including hematopoiesis and inflammation. Aging is associated with the onset of clonal hematopoiesis (CH) of indeterminate potential, putatively associated with a higher risk of progression to hematological malignancies such as myelodysplastic syndromes or acute myeloid leukemia. Moreover, CH may participate to create a pro-inflammatory environment contributing to the pathogenesis of age-related diseases, such as cardiovascular diseases. This is likely to be driven by or translated in changes in bone marrow (BM) and/or peripheral blood (PB) soluble factors for which reference values still remain unclear, because BM cytokines levels have never been determined in strictly selected healthy people. Indeed, control BM samples classically used in studies are from subjects undergoing surgeries for non-hematologic causes, such as total hip replacement or cardiac surgery, patients suffering from immune thrombocytopenic purpura, brain death patients or allogeneic BM donors. In this study, the BM and PB plasma concentrations of 49 hematopoietic and inflammatory cytokines were measured in a representative panel of 94 healthy adult volunteers and the results were analyzed considering their age and presence of CH. METHOD Ninety-four healthy donors aged from 18.6 to 80.1 years old (yo), including 58 women were recruited for this study (HEALTHOX protocol, CPP Tours, AFSSAPS identifier ID-RCB: 2016-A00571-50 and ClinicalTrials.gov # NCT02789839). The presence or absence of CH (>1% of variant allele frequency) in this cohort is already known (Guermouche H, Ravalet N et al, Blood Adv 2020;4(15):3550-3557). BM samples were obtained through sternal aspiration using a classical procedure in France, and PB sampling was performed at the same time by venipuncture. Samples were collected on sodium heparin or EDTA, centrifuged twice (1200 g, 10 min, 20 C°), aliquoted and stored at -80°C. A 48-plex human cytokine panel assay was used to quantify 48 human cytokines in PB and BM plasmas [beta-NGF, CCL2, CCL3, CCL4, CCL5, CCL7, CCL11, CCL27, CLEC11A, CXCL1, CXCL8, CXCL9, CXCL10, CXCL12, FGF-2, G-CSF, GM-CSF, HGF, IFN-alpha-2, IFN-gamma, IL-1 alpha, IL-1 beta, IL-1ra, IL-2, IL-2-RA, IL-3, IL-4, IL-5, IL-6, IL-7, IL-9, IL-10, IL-12, IL-12B, IL-13, IL-15, IL-16, IL-17A, IL-18, KITLG, LIF, LT-alpha, M-CSF, MIF, PDGF subunit B, TNF, TNFSF10, VEGF-A]. MIF and FLT3L quantification were performed by ELISA. Regarding CH, the controls were subjects older than 50 yo without CH. Statistical analyses were performed with the R (3.6.3) and Rstudio version 1.2.5042 (www.rstudio.org) software. Comparisons were computed by Wilcoxon and Kruskal-Wallis tests. All pairwise multiple comparisons were performed using Dunn's-test for multiple comparisons of independent samples (PMCMR package). Correlations between cytokine levels in PB and BM were tested with Pearson and Spearman methods. Correlation matrices were plotted using the "corrplot" package. RESULTS CH was detected in 16 volunteers, mostly in individuals over 50 yo. BM and PB plasma samples were studied in 3 age-groups: 18-40, 40-60 and 60-80 yo. With aging, variations were observed for 18 BM cytokine levels, with 7 increasing (FLT3L, CXCL9, HGF, FGF-2, CCL27, IL-16, IL-18) and 8 decreasing (G-CSF, TNF, IL-2, IL-15, IL-17a, IL-4, LT-alpha, IL-1 alpha). In PB, 10 cytokines significantly increased with age (CXCL9, FLT3L, CCL27, CXCL10, HGF, CCL11, IL-16, IL-6, IL-1 beta, CCL2). CH was associated with significantly higher BM levels of MIF and IL-1 beta, lower BM levels of IL-9 and IL-5 and higher PB levels of IL-15, VEGF-A, IL-2, CXCL8, CXCL1 and G-CSF (Table). CONCLUSION In this study and for the first time, we concomitantly analyzed BM and PB concentrations of a panel of hematopoietic and inflammatory cytokines in a cohort of strictly selected healthy volunteers. In addition to the establishment of reference values, useful for various biological studies, and correlations between blood and BM levels, we identify variations in the BM of key cytokines according to age and CH. The differences in these cytokine concentrations, either as causes or as consequences, may shape both the BM microenvironment and hematopoietic processes, eventually leading to the beginning of age-related myeloid malignancies or inflammatory conditions. Figure 1 Figure 1. Disclosures Hirsch: Daiichi Sankyo Oncology: Consultancy; Novartis Pharma: Consultancy. Suner: Sanofi - Genzyme: Consultancy. Delhommeau: Celgene: Consultancy; BMS: Consultancy; Novartis: Consultancy.

Myelodysplastic syndromes (MDS) are a heterogeneous group of clonal stem cell disorders with an inherent tendency for transformation in secondary acute myeloid leukemia. This study focused on the redox metabolism of bone marrow (BM) cells from 97 patients compared with 25 healthy controls. The level of reactive oxygen species (ROS) was quantified by flow cytometry in BM cell subsets as well as the expression level of 28 transcripts encoding for major enzymes involved in the antioxidant cellular response. Our results highlight increased ROS levels in BM nonlymphoid cells and especially in primitive CD34posCD38low progenitor cells. Moreover, we identified a specific antioxidant signature, dubbed “antioxidogram,” for the different MDS subgroups or secondary acute myeloblastic leukemia (sAML). Our results suggest that progression from MDS toward sAML could be characterized by 3 successive molecular steps: (1) overexpression of enzymes reducing proteic disulfide bonds (MDS with