Small Paroxysmal Nocturnal Hemoglobinuria Clones in Autoimmune Hemolytic Anemia: Clinical Implications and Different Cytokine Patterns in Positive and Negative Patients

Autoimmune hemolytic anemia (AIHA) is characterized by immune mediated erythrocytes destruction by autoantibodies with or without complement activation. Additional pathologic mechanisms include cellular cytotoxicity, cytokline dysregulation, and inadequate bone marrow compensation with fibrosis/dyserythropoiesis. The latter resembles that of bone marrow failures, namely aplastic anemia and myelodysplastic syndromes. Paroxysmal nocturnal hemoglobinuria (PNH) clones are increasingly recognized in bone marrow failure syndromes, and their selection and expansion are thought to be mediated by immune mechanisms. In this study, we aimed to evaluate the prevalence of PNH clones in 99 patients with primary AIHA, and their correlations with disease features and outcomes. Moreover, in the attempt to disclose the physiopathology of PNH positivity in AIHA, serum levels of several immunomodulatory cytokines were tested. A PNH clone was found in 37 AIHA patients (37,4%), with a median size of 0.2% on granulocytes (range 0.03\u201385). Two patients showed a large clone (16 and 85%) and were therefore considered as AIHA/PNH association and not included in further analysis. Compared to PNH negative, PNH positive cases displayed a higher hemolytic pattern with adequate bone marrow compensation. AIHA type, response to therapy, complications and outcome were comparable between the two groups. Regarding cytokine levels, IFN-\u3b3 and IL-17 were lower in PNH positive vs. PNH negative AIHAs (0.3 \ub1 0.2 vs. 1.33 \ub1 2.5; 0.15 \ub1 0.3 vs. 3,7 \ub1 9.1, respectively, p = 0.07 for both). In PNH positive AIHAs, IFN-\u3b3 positively correlated with reticulocytes (r = 0.52, p = 0.01) and with the bone marrow responsiveness index (r = 0.69, p = 0.002). Conversely, IL-6 and IL-10 showed the same pattern in PNH positive and PNH negative AIHAs. IL-6 levels and TGF-\u3b2 positively correlated with clone size (r = 0.35, p = 0.007, and r = 0.38, p = 0.05, respectively), as well as with LDH values (r = 0.69, p = 0.0003, and r = 0.34, p = 0.07, respectively). These data suggest testing PNH clones in AIHA since their prevalence is not negligible, and may correlate with a prominent hemolytic pattern, a higher thrombotic risk, and a different therapy indication. PNH testing is particularly advisable in complex cases with inadequate response to AIHA-specific therapy. Cytokine patterns of PNH positive and negative AIHAs may give hints about the pathogenesis of highly hemolytic AIHA

Nonmyeloablative Peripheral Blood Haploidentical Stem Cell Transplantation for Refractory Severe Aplastic Anemia

New transplant approaches are urgently needed for patients with refractory severe aplastic anemia (SAA) who lack a matched sibling or unrelated donor (UD) or who have failed UD or cord blood transplant. Patients with refractory SAA are at risk of later clonal evolution to myelodysplastic syndrome and acute leukemia. We report our pilot findings with haploidentical hematopoietic stem cell transplantation (haploHSCT) using uniform reduced-intensity conditioning with postgraft high-dose cyclophosphamide in 8 patients with refractory SAA or patients who rejected a prior UD or cord blood transplant. Six of 8 patients engrafted. Graft failure was associated with donor-directed HLA antibodies, despite intensive pre-HSCT desensitization with plasma exchange and rituximab. There was only 1 case of grade II skin graft-versus-host disease. We show that haploHSCT can successfully rescue refractory SAA patients who lack donor-directed HLA antibodies but not in the presence of donor-directed HLA antibodies. This novel protocol for haploHSCT for SAA has been adopted by the European Group for Blood and Marrow Transplantation Severe Aplastic Anaemia Working Party for a future noninterventional, observational study to further evaluate its efficacy

Preclinical modeling of myelodysplastic syndromes

Myelodysplastic syndromes (MDS) represent a heterogeneous group of hematological clonal disorders. Here, we have tested the bone marrow (BM) cells from 38 MDS patients covering all risk groups in two immunodeficient mouse models: NSG and NSG-S. Our data show comparable level of engraftment in both models. The level of engraftment was patient specific with no correlation to any specific MDS risk group. Furthermore, the co-injection of mesenchymal stromal cells (MSCs) did not improve the level of engraftment. Finally, we have developed an in vitro two-dimensional co-culture system as an alternative tool to in vivo. Using our in vitro system, we have been able to co-culture CD34+cells from MDS patient BM on auto- and/or allogeneic MSCs over 4 weeks with a fold expansion of up to 600 times. More importantly, these expanded cells conserved their MDS clonal architecture as well as genomic integrity

SARS-CoV-2 infection in aplastic anaemia

Not available

Integrative Genomics Identifies the Molecular Basis of Resistance to Azacitidine Therapy in Myelodysplastic Syndromes

© 2017 The Author(s) Myelodysplastic syndromes and chronic myelomonocytic leukemia are blood disorders characterized by ineffective hematopoiesis and progressive marrow failure that can transform into acute leukemia. The DNA methyltransferase inhibitor 5-azacytidine (AZA) is the most effective pharmacological option, but only ∼50% of patients respond. A response only manifests after many months of treatment and is transient. The reasons underlying AZA resistance are unknown, and few alternatives exist for non-responders. Here, we show that AZA responders have more hematopoietic progenitor cells (HPCs) in the cell cycle. Non-responder HPC quiescence is mediated by integrin α5 (ITGA5) signaling and their hematopoietic potential improved by combining AZA with an ITGA5 inhibitor. AZA response is associated with the induction of an inflammatory response in HPCs in vivo. By molecular bar coding and tracking individual clones, we found that, although AZA alters the sub-clonal contribution to different lineages, founder clones are not eliminated and continue to drive hematopoiesis even in complete responders