- Gene mutations in bone marrow failure syndromes. [Journal Article]
- RKRinsho Ketsueki 2016; 57(12):2519-2525
- Acquired bone marrow failure syndromes consist of aplastic anemia, paroxysmal nocturnal hemoglobinuria (PNH), and myelodysplastic syndromes (MDS). Clonal hematopoiesis is frequently observed in non-n...
Acquired bone marrow failure syndromes consist of aplastic anemia, paroxysmal nocturnal hemoglobinuria (PNH), and myelodysplastic syndromes (MDS). Clonal hematopoiesis is frequently observed in non-neoplastic disorders, aplastic anemia and PNH as well as a neoplastic phenotype, MDS. However, the significance of such clonal hematopoiesis, particularly in aplastic anemia, remains to be elucidated. Recent advancements in next generation sequencing technology have revealed a diverse clonal structure in these bone marrow failure syndromes, as well as in age-related clonal hematopoiesis in healthy people. In this review article, we describe gene mutations in bone marrow failure syndromes, together with those detected in healthy people.
- Development of Autologous C5 Vaccine Nanoparticles to Reduce Intravascular Hemolysis in Vivo. [Journal Article]
- ACACS Chem Biol 2017 Jan 12
- The complement system is emerging as a new target for treating many diseases. For example, Eculizumab, a humanized monoclonal antibody against complement component 5 (C5), has been approved for parox...
The complement system is emerging as a new target for treating many diseases. For example, Eculizumab, a humanized monoclonal antibody against complement component 5 (C5), has been approved for paroxysmal nocturnal hemoglobinuria (PNH) in which patient erythrocytes are lysed by complement. In this study, we developed vaccines to elicit autologous anti-C5 antibody production in mice for complement inhibition. Immunization of mice with a conservative C5 xenoprotein raised high titers of IgG's against the xenogenous C5, but these antibodies did not reduce C5 activity in the blood. In contrast, an autologous mouse C5 vaccine containing multiple predicted epitopes together with a tolerance-breaking peptide was found to induce anti-C5 autoantibody production in vivo, resulting in decreased hemolytic activity in the blood. We further validated a peptide epitope within this C5 vaccine and created recombinant virus-like particles (VLPs) displaying this epitope fused with the tolerance breaking peptide. Immunizing mice with these novel nanoparticles elicited strong humoral responses against recombinant mouse C5, reduced hemolytic activity, and protected the mice from complement-mediated intravascular hemolysis in a model of PNH. This proof-of-concept study demonstrated that autologous C5-based vaccines could be an effective alternative or supplement for treating complement-mediated diseases such as PNH.
- Development of pro-inflammatory phenotype in monocytes after engulfing Hb-activated platelets in hemolytic disorders. [Journal Article]
- CIClin Immunol 2016 Dec 28
- Monocytes and macrophage combat infections and maintain homeostatic balance by engulfing microbes and apoptotic cells, and releasing inflammatory cytokines. Studies have described that these cells de...
Monocytes and macrophage combat infections and maintain homeostatic balance by engulfing microbes and apoptotic cells, and releasing inflammatory cytokines. Studies have described that these cells develop anti-inflammatory properties upon recycling the free-hemoglobin (Hb) in hemolytic conditions. While investigating the phenotype of monocytes in two hemolytic disorders-paroxysmal nocturnal hemoglobinuria (PNH) and sickle cell disease (SCD), we observed a high number of pro-inflammatory (CD14(+)CD16(hi)) monocytes in these patients. We further investigated in vitro the phenotype of these monocytes and found an estimated 55% of CD14(+) cells were transformed into the CD14(+)CD16(hi) subset after engulfing Hb-activated platelets. The CD14(+)CD16(hi) monocytes, which were positive for both intracellular Hb and CD42b (platelet marker), secreted significant amounts of TNF-α and IL-1β, unlike monocytes treated with only free Hb, which secreted more IL-10. We have shown recently the presence of a high number of Hb-bound hyperactive platelets in patients with both diseases, and further investigated if the monocytes engulfed these activated platelets in vivo. As expected, we found 95% of CD14(+)CD16(hi) monocytes with both intracellular Hb and CD42b in both diseases, and they expressed high TNF-α. Furthermore our data showed that these monocytes whether from patients or developed in vitro after treatment with Hb-activated platelets, secreted significant amounts of tissue factor. Besides, these CD14(+)CD16(hi) monocytes displayed significantly decreased phagocytosis of E. coli. Our study therefore suggests that this alteration of monocyte phenotype may play a role in the increased propensity to pro-inflammatory/coagulant complications observed in these hemolytic disorders-PNH and SCD.
- Buried Hydrogen Bond Interactions Contribute to the High Potency of Complement Factor D Inhibitors. [Journal Article]
- AMACS Med Chem Lett 2016 Dec 08; 7(12):1092-1096
- Aberrant activation of the complement system is associated with diseases, including paroxysmal nocturnal hemoglobinuria and age-related macular degeneration. Complement factor D is the rate-limiting ...
Aberrant activation of the complement system is associated with diseases, including paroxysmal nocturnal hemoglobinuria and age-related macular degeneration. Complement factor D is the rate-limiting enzyme for activating the alternative pathway in the complement system. Recent development led to a class of potent amide containing pyrrolidine derived factor D inhibitors. Here, we used biochemical enzymatic and biolayer interferometry assays to demonstrate that the amide group improves the inhibitor potency by more than 80-fold. Our crystal structures revealed buried hydrogen bond interactions are important. Molecular orbital analysis from quantum chemistry calculations dissects the chemical groups participating in these interactions. Free energy calculation supports the differential contributions of the amide group to the binding affinities of these inhibitors. Cell-based hemolysis assay confirmed these compounds inhibit factor D mediated complement activation via the alternative pathway. Our study highlights the important interactions contributing to the high potency of factor D inhibitors reported recently.
- HbS Binding to GP1bα Activates Platelets in Sickle Cell Disease. [Journal Article]
- PlosPLoS One 2016; 11(12):e0167899
- Intravascular hemolysis increases the risk of thrombosis in hemolytic disorders. Our previous study showed that the binding of adult hemoglobin (HbA) to glycoprotein (GP) 1bα induced the activation o...
Intravascular hemolysis increases the risk of thrombosis in hemolytic disorders. Our previous study showed that the binding of adult hemoglobin (HbA) to glycoprotein (GP) 1bα induced the activation of platelets. The elevated plasma Hb or platelet surface bound Hb positively correlated with platelet activation in patients with paroxysmal nocturnal hemoglobinuria (PNH). Furthermore, this study shows that the sickle Hb [HbS, occurs due to single nucleotide polymorphism at A>T of β-globin gene of Hb and causes sickle cell disease (SCD)] also bound to GP1bα and activated platelets in a concentration-dependent manner. The HbS bound to glycocalicin (extramembranous part of GP1bα) with KD ~ 10.46 ± 3 μM. HbS induced phosphorylation of signaling adapter proteins, such as Lyn, PI3K, Akt and ERK in platelets, and also increased the surface expression of platelet activation markers such as P-selectin (10.7 fold) and PAC1 binding (10.4 fold) in platelet surface in a concentration-dependent manner. HbS also increased the platelet microparticle-generation (4.7 fold) and thrombus-formation (4.3 fold) in a concentration-dependent manner. An elevated level of extracellular Hb in plasma correlated directly with platelet activation markers such as P-selectin (r = 0.7947), PAC1 binding (r = 0.5914) on platelet surface and plasma levels of platelet-derived microparticles (r = 0.7834) in patients with SCD. Our study therefore suggests that the HbS-induced platelet activation may play a crucial role in intravascular clot formation observed in SCD patients characterized by high propensity to vascular occlusion and hypercoagulable states.
- Update on the diagnosis and management of paroxysmal nocturnal hemoglobinuria. [Journal Article]
- HAHematology Am Soc Hematol Educ Program 2016 Dec 02; 2016(1):208-216
- Once suspected, the diagnosis of paroxysmal nocturnal hemoglobinuria (PNH) is straightforward when flow cytometric analysis of the peripheral blood reveals a population of glycosyl phosphatidylinosit...
Once suspected, the diagnosis of paroxysmal nocturnal hemoglobinuria (PNH) is straightforward when flow cytometric analysis of the peripheral blood reveals a population of glycosyl phosphatidylinositol anchor protein-deficient cells. But PNH is clinically heterogeneous, with some patients having a disease process characterized by florid intravascular, complement-mediated hemolysis, whereas in others, bone marrow failure dominates the clinical picture with modest or even no evidence of hemolysis observed. The clinical heterogeneity is due to the close, though incompletely understood, relationship between PNH and immune-mediated bone marrow failure, and that PNH is an acquired, nonmalignant clonal disease of the hematopoietic stem cells. Bone marrow failure complicates management of PNH because compromised erythropoiesis contributes, to a greater or lesser degree, to the anemia; in addition, the extent to which the mutant stem cell clone expands in an individual patient determines the magnitude of the hemolytic component of the disease. An understanding of the unique pathobiology of PNH in relationship both to complement physiology and immune-mediated bone marrow failure provides the basis for a systematic approach to management.
- Transplantation for bone marrow failure: current issues. [Journal Article]
- HAHematology Am Soc Hematol Educ Program 2016 Dec 02; 2016(1):90-98
- The preferred treatment of idiopathic aplastic anemia (AA) is allogeneic hematopoietic stem cell transplantation (HSCT) from a human leukocyte antigen (HLA)-identical sibling donor. Transplantation f...
The preferred treatment of idiopathic aplastic anemia (AA) is allogeneic hematopoietic stem cell transplantation (HSCT) from a human leukocyte antigen (HLA)-identical sibling donor. Transplantation from a well-matched unrelated donor (MUD) may be considered for patients without a sibling donor after failure of immunosuppressive therapy, as may alternative transplantation (mismatched, cord blood or haplo-identical HSCT) for patients without a MUD. HSCT may also be contemplated for congenital disorders in cases of pancytopenia or severe isolated cytopenia. Currently, HSCT aims are not only to cure patients but also to avoid long-term complications, notably chronic graft-versus-host disease (GVHD), essential for a good quality of life long term. This paper summarizes recent advances in HSCT for idiopathic and inherited AA disorders. The effect of age on current transplantation outcomes, the role of transplantation in paroxysmal nocturnal hemoglobinuria, and the prevention of GVHD are also discussed. Emerging strategies regarding the role of up-front unrelated donor and alternative donor HSCT in idiopathic AA, along with advances in the treatment of clonal evolution in Fanconi anemia, are also examined.
- Acquired somatic mutations in PNH reveal long-term maintenance of adaptive NK cells independent from HSPC. [Journal Article]
- BloodBlood 2016 Nov 30
- Natural killer (NK) cells have long been considered short-lived effectors of innate immunity. However, recent animal models and human studies suggest that subsets of NK cells have adaptive features. ...
Natural killer (NK) cells have long been considered short-lived effectors of innate immunity. However, recent animal models and human studies suggest that subsets of NK cells have adaptive features. We investigate clonal relationships of various NK cell subsets, including the adaptive population, by taking advantage of naturally occurring X-linked somatic PIGA mutations in hematopoietic stem and progenitor cells (HSPC) from patients with paroxysmal nocturnal hemoglobinuria (PNH). The affected HSPCs and their progeny lack expression of glycosylphosphatidylinositol (GPI) anchors on their cell surfaces, allowing quantification of PIGA-mutant (GPI-negative) HSPC-derived peripheral blood cell populations. The fraction of GPI-negative cells within the CD56(dim) NK cells was markedly lower than that of neutrophils and the CD56(bright) NK cell compartments. This discrepancy was most prominent within the adaptive CD56(dim) NK cell population lacking PLZF expression. The functional properties of these adaptive NK cells were similar in PNH patients and healthy individuals. Our findings support the existence of a long-lived, adaptive NK cell population maintained independently from HSPC.
- Different clinical characteristics of paroxysmal nocturnal hemoglobinuria in pediatric and adult patients. [Journal Article]
- HHaematologica 2016 Nov 24
New Search Next
- Immune Hemolytic Anemia (Paroxysmal Cold Hemoglobinuria) Preceding Burkitt Lymphoma in a 12-Year-Old Child. [Journal Article]
- JPJ Pediatr Hematol Oncol 2017; 39(1):e25-e26
- Autoimmune hemolytic anemia (AIHA) in childhood, including paroxysmal cold hemoglobinuria, is an uncommon, potentially life-threatening disorder. AIHA is a recognized complication of several varietie...
Autoimmune hemolytic anemia (AIHA) in childhood, including paroxysmal cold hemoglobinuria, is an uncommon, potentially life-threatening disorder. AIHA is a recognized complication of several varieties of lymphoproliferative disorders, including high-grade B-cell lymphoma, but it has not been associated with Burkitt lymphoma in people without an underlying immunodeficiency. When AIHA occurs in association with lymphoproliferative disorders, it may precede or accompany the diagnosis of malignant disease or herald relapse. We report a novel case of a previously healthy child diagnosed with paroxysmal cold hemoglobinuria 14 months preceding the development of Burkitt lymphoma.