ISSN / EISSN : 0390-6078 / 1592-8721
Current Publisher: Ferrata Storti Foundation (Haematologica) (10.3324)
Total articles ≅ 5,248
Latest articles in this journal
Chemoresistance of leukemic cells has largely been attributed to clonal evolution secondary to accumulating mutations. Here, we show that a subset of leukemic blasts in contact with the mesenchymal stroma undergo cellular conversion into a distinct cell type that exhibits a stem cell-like phenotype and chemoresistance. These stroma-induced changes occurred in a reversible and stochastic manner driven by cross-talk, whereby stromal contact induces IL-4 in leukemic cells that in turn targets the mesenchymal stroma to facilitate the development of new subset. This mechanism was dependent on IL-4 mediated up-regulation of vascular cell adhesion molecule-1 in mesenchymal stroma, causing tight adherence of leukemic cells to mesenchymal progenitors for generation of new subsets. Together, our study reveals another class of chemoresistance in leukemic blasts via functional evolution through stromal cross-talk, and demonstrates dynamic switching of leukemic cell fates that could cause a non-homologous response to chemotherapy in concert with the patientspecific microenvironment.
Pediatric-onset Evans syndrome (pES) is defined by both immune thrombocytopenic purpura (ITP) and autoimmune hemolytic anemia (AIHA) before the age of 18 years. There have been no comprehensive long-term studies of this rare disease, which can be associated to various immunopathological manifestations (IMs). We report outcomes of the 151 patients with pES and more than 5 years of follow-up from the nationwide French prospective OBS’CEREVANCE cohort. Median age at final follow-up was 18.5 (6.8–50.0) years and the median follow-up period was 11.3 (5.1–38.0) years. At 10 years, ITP and AIHA were in sustained complete remission in 54.5% and 78.4% of patients, respectively. The frequency and number of clinical and biological IMs increased with age: at 20 years old, 74% had at least one clinical cIM. A wide range of cIMs occurred, mainly lymphoproliferation, dermatological, gastrointestinal/hepatic and pneumological IMs. The number of cIMs was associated with a subsequent increase in the number of second-line treatments received (other than steroids and immunoglobulins; hazard ratio, 1.4; 95% confidence interval, 1.15–1.60; p = 0.0002, Cox proportional hazards method). Survival at 15 years after diagnosis was 84%. Death occurred at a median age of 18 (1.7–31.5) years, and the most frequent cause was infection. The number of second-line treatments and severe/recurrent infections were independently associated with mortality. In conclusion, longterm outcomes of pES showed remission of cytopenias but frequent IMs linked to high secondline treatment burden. Mortality was associated to drugs and/or underlying immunodeficiencies, and adolescents-young adults are a high-risk subgroup.
Diamond-Blackfan anemia (DBA) is an inherited bone marrow failure disorder with pure red blood cell aplasia associated with physical malformations and a predisposition to cancer. Twenty-five percent of patients with DBA have mutations in a gene encoding ribosomal protein S19 (RPS19). Our previous proof-of-concept studies demonstrated that DBA phenotype could be successfully treated using lentiviral vectors in Rps19-deficient DBA mice. In our present study, we developed a clinically applicable single gene self-inactivating lentiviral vector, containing the human RPS19 cDNA driven by the human elongation factor 1α short promoter, that can be used for clinical gene therapy development for RPS19-deficient DBA. We examined the efficacy and safety of the vector in a Rps19-deficient DBA mouse model and in human primary RPS19-deficient CD34+ cord blood cells. We observed that transduced Rps19-deficient bone marrow cells could reconstitute mice longterm and rescue the bone marrow failure and severe anemia observed in Rps19-deficient mice, with a low risk of mutagenesis and a highly polyclonal insertion site pattern. More importantly, the vector can also rescue impaired erythroid differentiation in human primary RPS19-deficient CD34+ cord blood hematopoietic stem cells. Collectively, our results demonstrate the efficacy and safety of using a clinically applicable lentiviral vector for the successful treatment of Rps19-deficient DBA in a mouse model and in human primary CD34+ cord blood cells. These findings show that this vector can be used to develop clinical gene therapy for RPS19-deficient DBA patients.
In this study, we characterize age-related phenotypes of human hematopoietic stem cells (HSCs). We report increased frequencies of HSC, HPC and lineage negative cells in the elderly but a decreased frequency of multi-lymphoid progenitors. Aged human HSCs further exhibited a delay in initiating division ex vivo though without changes in their division kinetics. The activity of the small RhoGTPase Cdc42 was elevated in aged human hematopoietic cells and we identified a positive correlation between Cdc42 activity and the frequency of HSCs upon aging. The frequency of human HSCs polar for polarity proteins was, similar to the mouse, decreased upon aging, while inhibition of Cdc42 activity via the specific pharmacological inhibitor of Cdc42 activity, CASIN, resulted in re-polarisation of aged human HSCs with respect to Cdc42. Elevated activity of Cdc42 in aged HSCs thus contributed to age-related changes in HSCs. Xeno-transplants, using NBSGW mice as recipients, showed elevated chimerism in recipients of aged compared to young HSCs. Aged HSCs treated with CASIN ex vivo displayed an engraftment profile similar to recipients of young HSCs. Taken together, our work reveals strong evidence for a role of elevated Cdc42 activity in driving aging of human HSCs, and similar to mice, this presents a likely possibility for attenuation of aging in human HSCs.
Graft-versus-host disease (GvHD) is a major cause of morbidity and mortality after allogeneic hematopoietic cell transplantation. We recently showed in murine studies and in vitro human models that adoptively transferred invariant natural killer T (iNKT) cells protect from GvHD and promote graft-versus-leukemia effects. The cellular mechanisms underlying GvHD prevention by iNKT cells in humans, however, remain unknown. To study relevant cellular interactions, dendritic cells (DCs) were either generated from monocytes or isolated directly from blood of healthy donors or GvHD patients and co-cultured in a mixed lymphocyte reaction (MLR) with T cells obtained from healthy donors or transplantation bags. Addition of culture-expanded iNKT cells to the MLR induced DC apoptosis in a cell contact-dependent manner, thereby preventing T-cell activation and proliferation. Annexin V/PI staining and image stream assays showed that CD4+CD8-, CD4-CD8+ and double negative iNKT cells are similarly able to induce DC apoptosis. Further MLR assays revealed that conventional DCs (cDCs) but not plasmacytoid DCs (pDCs) could induce alloreactive T-cell activation and proliferation. Interestingly, cDCs were also more susceptible to apoptosis induced by iNKT cells, which correlates with their higher CD1d expression, leading to a bias in favor of pDCs. Remarkably, these results could also be observed in GvHD patients. We propose a new mechanism how ex vivo expanded human iNKT cells prevent alloreactivity of T cells. iNKT cells modulate T-cell responses by selective apoptosis of DC subsets, resulting in suppression of T-cell activation and proliferation while enabling beneficial immune responses through pDCs.
Transfusion-dependent patients typically develop iron-induced cardiomyopathy, liver disease, and endocrine complications. We aimed to estimate the incidence of endocrine disorders in transfusion-dependent thalassemia (TDT) patients during long-term iron-chelation therapy with deferasirox (DFX).We developed a multicentre follow-up study of 426 TDT patients treated with once-daily DFX for a median duration of 8 years, up to 18.5 years. At baseline, 118, 121, and 187 patients had 0, 1, or ≥2 endocrine diseases respectively. 104 additional endocrine diseases were developed during the follow-up. The overall risk of developing a new endocrine complication within 5 years was 9.7% (95%CI=6.3–13.1). Multiple Cox regression analysis identified 3 key predictors: age showed a positive log-linear effect (adjusted HR for 50% increase=1.2, 95%CI=1.1–1.3, P=0.005), the serum concentration of thyrotropin (TSH) showed a positive linear effect (adjusted HR for 1 mIU/L increase=1.3, 95%CI=1.1–1.4, P
APR-246 is a promising new therapeutic agent that targets p53 mutated proteins in myelodysplastic syndromes and in acute myeloid leukemia. APR-246 reactivates the transcriptional activity of p53 mutants by facilitating their binding to DNA target sites. Recent studies in solid cancers have found that APR-246 can also induce p53-independent cell death. In this study, we demonstrate that AML cell death occurring early after APR-246 exposure is suppressed by iron chelators, lipophilic antioxidants and inhibitors of lipid peroxidation, and correlates with the accumulation of markers of lipid peroxidation, thus fulfilling the definition of ferroptosis, a recently described cell death process. The capacity of AML cells to detoxify lipid peroxides by increasing their cystine uptake to maintain major antioxidant molecule glutathione biosynthesis after exposure to APR-246 may be a key determinant of sensitivity to this compound. The association of APR-246 with induction of ferroptosis (either by pharmacological compounds, or genetic inactivation of SLC7A11 or GPX4) had a synergistic effect on the promotion of cell death, both in vivo and ex vivo.
Activated factor VII (FVIIa), the first protease of clotting, expresses its physiological procoagulant potential only after complexing with tissue factor (TF) exposed to blood. Deep knowledge of the FVIIa-TF complex and F7 gene helps to understand the Janus-faced clinical findings associated to low or elevated FVII activity (FVIIc). Congenital FVII deficiency, the most frequent among the recessively inherited bleeding disorders, is caused by heterogeneous mutations in the F7 gene. Complete FVII deficiency causes perinatal lethality. A wide range of bleeding symptoms, from life-threatening intracranial hemorrhage to mild mucosal bleeding, is observed in patients with apparently modest differences in FVIIc levels. Though clinically relevant FVIIc threshold levels are still uncertain, effective management, including prophylaxis, has been devised, substantially improving the quality of life of patients. The exposure of TF in diseased arteries fostered investigation on the role of FVII in cardiovascular disease. FVIIc levels were found to be predictors of cardiovascular death and to be markedly associated to F7 gene variation. These genotype-phenotype relationships are among the most extensively investigated in humans. Genome-wide analyses extended association to numerous loci that, together with F7, explain >50% of FVII level plasma variance. However, the ability of F7 variation to predict thrombosis was not consistently evidenced in the numerous population studies. Main aims of this review are to highlight i) the biological and clinical information that distinguishes FVII deficiency from the other clotting disorders and ii) the impact exerted by genetically predicted FVII level variation on bleeding as well as on the thrombotic states.
Erythroblast maturation in mammals is dependent on organelle clearance throughout terminal erythropoiesis. We studied the role of the outer mitochondrial membrane protein VDAC1 (Voltage-Dependent Anion Channel-1) in human terminal erythropoiesis. We show that shRNA-mediated downregulation of VDAC1 accelerates erythroblast maturation. Thereafter, erythroblasts are blocked at orthochromatic stage, exhibiting a significant decreased level of enucleation, concomitant with an increased cell death. We demonstrate that mitochondria clearance starts at the transition from basophilic to polychromatic erythroblast, and that VDAC1 downregulation induces the mitochondrial retention. In damaged mitochondria from non-erythroid cells, VDAC1 was identified as a target for Parkin-mediated ubiquitination to recruit the phagophore. Here, we showed that VDAC1 is involved in phagophore’s membrane recruitment regulating selective mitophagy of still functional mitochondria from human erythroblasts. These findings demonstrate for the first time a crucial role for VDAC1 in human erythroblast terminal differentiation, regulating mitochondria clearance.