Danazol increases T regulatory cells in patients with aplastic anemia

Objectives: Danazol is an attenuated androgen and is used in the treatment of aplastic anemia (AA) in resource constraint settings. We chose to study the role of CD4+ CD25^high CD127^low FoxP3+ T regulatory cells (T-regs) in the pathophysiology of AA and their response to treatment with Danazol alone or in combination with immunosuppressive treatment (IST).

Methods: T-regs’ percentages of 25 acquired idiopathic AA patients and 25 healthy controls who completed study protocol were analyzed by performing multicolor flowcytometry on peripheral blood samples.

Results: More than one-third (36%) of AA patients in our study received Danazol as monotherapy, whereas less than a third (32%) each received standard doses of IST with equine Anti Thymocyte Globulin (ATG) and Cyclosporine combination, or Cyclosporine and Danazol combination, respectively. Results showed that all AA patients had a significantly lower percentage of T-regs at the time of diagnosis when compared to healthy controls (p?p?Discussion: The rise in T-regs’ percentage was higher in patients treated with Danazol alone when compared to standard IST (ATG with Cyclosporine), or Cyclosporine with Danazol combinations (p?=?0.585).

Conclusion: We conclude that Danazol also leads to increase in T-regs in acquired idiopathic AA.     

Perforin gene mutations in patients with acquired aplastic anemia

Perforin is a cytolytic protein expressed mainly in activated cytotoxic lymphocytes and natural killer cells. Inherited perforin mutations account for 20% to 40% of familial hemophagocytic lymphohistiocytosis, a fatal disease of early childhood characterized by the absence of functional perforin. Aplastic anemia, the paradigm of immune-mediated bone marrow failure syndromes, is characterized by hematopoietic stem cell destruction by activated T cells and Th1 cytokines. We examined whether mutations in the perforin gene occurred in acquired aplastic anemia. Three nonsynonymous PRF1 mutations among 5 unrelated patients were observed. Four of 5 patients with the mutations showed some hemophagocytosis in the bone marrow at diagnosis. Perforin protein levels in these patients were very low or absent, and perforin granules were completely absent. Natural killer (NK) cell cytotoxicity from these patients was significantly decreased. Our data suggest that PRF1 genetic alterations help explain the aberrant proliferation and activation of cytotoxic T cells and may represent genetic risk factors for bone marrow failure.     

Clonal hematopoiesis in patients with acquired aplastic anemia.

To determine whether patients with acquired asplastic anemia (AA) exhibit clonal hematopoiesis, we used restriction fragment length polymorphisms of the X-linked genes phosphoglycerate kinase (PGK1) and hypoxanthine phosphoribosyltransferase (HPRT) and the X-linked probe M27 beta. Of the 19 female patients studied, 18 (95%) patients were informative for at least one marker. Of these, eight patients (42%) were heterozygous for PGK1, two (11%) for HPRT, and 16 (84%) for M27 beta. In 13 (72%) patients, a monoclonal pattern was found. Analysis of purified cell suspensions of four of these patients showed that both myeloid and lymphoid cells were of monoclonal origin, indicating the involvement of an early stem cell. The four patients who were studied at presentation all showed a monoclonal pattern. One of these patients showed a spontaneous recovery despite persistent clonal hematopoiesis. The presence of either clonal or polyclonal hematopoiesis did not show a correlation with the response to antithymocyte globulin (ATG) treatment. A relapse after ATG was also seen in a patient exhibiting polyclonal hematopoiesis. Conversely, a monoclonal pattern did not preclude the occurrence of a partial or complete response to ATG. Other potential markers to study clonality, including cytogenetic abnormalities or point mutations of the N-ras protooncogene, were not found in any of the patients. It is concluded that patients with AA may exhibit clonal hematopoiesis. The significance with respect to evolution to disorders with clonal hematopoiesis like paroxysmal nocturnal hemoglobinuria, myelodysplasia, and acute leukemia remains to be determined.     

Prognosis in acquired aplastic anemia

To study prognostic factors 38 consecutive patients with aplastic anemia were evaluated until death or over a follow-up period of at least 4 years. A prognostic formula was devised by multivariate analysis for prediction of short-term survivors at diagnosis of aplastic anemia: Using the initial percentage of nonmyeloid cells in the marrow aspirate and the neutrophil count in peripheral blood, survival of less than 4 months is predicted with a probability of 89% (sensitivity 80%). The lowest blood counts during the course of the disease are useful to predict the outcome in more chronic courses of aplastic anemia: A reticulocytopenia below 5 X 10(9)/1, a neutropenia below 0.1 X 10(9)/1 or a thrombocytopenia below 5 X 10(9)/1 all resulted in an ultimate mortality of over 90%. However, if none of these threshold values were reached, a 4 year survival of 71% was observed. Thus, 5 X 10(9) reticulocytes/1, 0.1 X 10(9) neutrophils/1 and 5 X 10(9) platelets/1 form a group of risk factors to predict a fatal or favorable outcome throughout the course of the disease.     

Androgen dependency in acquired aplastic anemia

We describe three patients with acquired aplastic anemia showing dependency on androgens, with blood counts that correlated directly with variation in oxymetholone dosage. In two of the patients, red cells, neutrophils and platelets showed parallel fluctuations, whereas in one patient the red cells and white cells, but not the platelets, fluctuated in relationship to oxymetholone therapy. There was no hematologic response to dromostanolone in two patients. These results support the benefit of androgen therapy in some patients with acquired aplastic anemia.     

Immunoregulatory cytokines gene polymorphisms in Egyptian patients affected with acquired aplastic anemia

The immune system is thought to play an important role in aplastic anemia (AA) in light of recent findings of hematologic reconstitution after immunosuppressive therapy. T cell activation, apoptosis, and the cytokines interferon- and TNF-α are suspected to play a role in the suppression of growth of progenitor cells and induced apoptosis in CD34 target cells, TGFβ is a multifunctional peptide, usually produced in latent form and requiring activation to produce a biological response. Also, TGF-β1 has been described as an important negative regulator of haemopoiesis. Over production of IL-6 is described in AA but is of unknown pathophysiological significance. To investigate the role of cytokine gene polymorphisms (IL-6/-174, TNF-α/-308, IFN-γ/+874, and TGFβ1/-509) in patients with acquired AA to assess if genotypes associated with higher or lower production were more prevalent than in established control population and to study the possible association of these genotypes with the disease severity. Fifty AA patients were included in this study. Polymerase chain reaction–amplification refractory mutation system (PCR–ARMS) technique was used to detect INF-γ single nucleotide polymorphism ?874A/T, and polymerase chain reaction–restriction fragment length polymorphism (PCR–RFLP) was used to assess IL-6-174 C/G, TNF-α-308G/A, and TGFb1-509C/T gene polymorphisms. Genotypes associated with high production of TNF-α, TGF-β and IFN-γ, and IL-6 were more frequent in patients than in control; no association was found between the presence of hypersecretory genotypes and the disease severity.     

Intrinsic impairment of CD4+CD25+ regulatory T cells in acquired aplastic anemia

Acquired aplastic anemia (AA) is an immune-mediated bone marrow (BM) failure attacked by autoreactive effector T cells and BM is the main target organ. CD4(+)CD25(+) regulatory T cells (Tregs) were believed to control development and progression of autoimmunity by suppressing autoreactive effector T cells, but little was known regarding the function of Tregs in AA. Our study demonstrated that both peripheral blood (PB) and BM had decreased frequencies of Tregs, accompanied with a reversed lower ratio of Treg frequencies between BM and PB in AA. PB Tregs in AA had impaired migratory ability because of lower CXCR4 (but not for CXCR7) expression. Interestingly, we first showed that impairment of Treg-mediated immunosuppression was intrinsic to Tregs, rather than resistance of effector T cells to suppression in AA by coculture assays and criss-cross experiments in vitro. Furthermore, Tregs in AA were less able to inhibit interferon-γ production by effector T cells. Defective immunosuppression by Tregs could contribute to impaired hematopoiesis conducted by effector T cells in vitro. Our study provided powerful evidence that impairment of Tregs played a critical role in the pathophysiology of AA. Thus, patients with AA might greatly benefit from a Treg-oriented immunosuppressive strategy.     

Molecular pathogenesis of acquired aplastic anemia

The application of next‐generation sequencing (NGS) has enhanced our understanding of the genetic landscape in acquired aplastic anemia (AA). Parallel progress has been in addressing aspects underlying immune dysregulation in disease pathogenesis. Novel insights into the molecular and biologic mechanisms have led to a shift in the paradigm of AA, from a solely autoimmune pathogenic concept toward its recognition as a multifaceted pathophysiology characterized by cytogenetic abnormalities, recurrent somatic mutations, telomere attrition, and immune dysregulation. The detection of recurrent driver mutations disrupting myelodysplastic syndrome (MDS)/acute myeloid leukemia (AML)‐associated genes has suggested a pathophysiologic link between clonal hematopoiesis in AA and the later development of these clonal disorders. Further, certain AA‐related somatic genetic alterations may have clinical implications on treatment response, disease progression, and survival following immunosuppressive therapy. Going forward, wider validation of these genetic abnormalities will allow for their incorporation into a more informative risk stratification system that does not rely solely on clinical factors.     

Treatment of acquired aplastic anemia in children

Aplastic anemia (AA) is an uncommon but serious disorder characterized by pancytopenia resulting from non-function of the bone marrow. The incidence of AA is approximately 3 fold more common in East Asia than in Europe and United States where yearly incidence rates are approximately two patients per one million.     

How I treat acquired aplastic anemia

Survival in severe aplastic anemia (SAA) has markedly improved in the past 4 decades because of advances in hematopoietic stem cell transplantation, immunosuppressive biologics and drugs, and supportive care. However, management of SAA patients remains challenging, both acutely in addressing the immediate consequences of pancytopenia and in the long term because of the disease's natural history and the consequences of therapy. Recent insights into pathophysiology have practical implications. We review key aspects of differential diagnosis, considerations in the choice of first- and second-line therapies, and the management of patients after immunosuppression, based on both a critical review of the recent literature and our large personal and research protocol experience of bone marrow failure in the Hematology Branch of the National Heart, Lung, and Blood Institute.     

Analysis of natural killer cells in patients with aplastic anemia

We have analyzed natural killer (NK) cells in 43 patients with severe aplastic anemia, using cytotoxicity assays and microfluorometry with monoclonal antibodies, prior to and after treatment with antithymocyte globulin (ATG). Before treatment, natural killer cell activity (NKa) in both peripheral blood and bone marrow was markedly decreased in 76% of patients as compared with normal controls. Although we have measured low NKa in patients receiving large numbers of blood transfusions (means = 150 U of RBCs), six aplastic patients had low NKa in the absence of transfusions, and the average number of transfusions in the total population was low (means = 24). Purification of larger granular lymphocytes (LGLs) from peripheral blood of aplastic anemia patients failed to recover significant NKa. Most of these large granular lymphocytes showed few azurophilic granules. NKa was appropriately enhanced in these patients samples by exposure of mononuclear cells to either interleukin 2 (IL-2) or interferon (IFN). Analysis of peripheral blood phenotypic markers showed that cells bearing Leu 7 antigen were in the normal range in aplastic anemia (means = 12% +/- 2%; normal = 16% +/- 2%), but there was a deficiency of Leu 11+ cells (means = 8% +/- 2%; normal = 15% +/- 2%). The number of Leu 11+ cells was well correlated with NKa. In 13 of 22 patients treated with ATG, NKa returned to the normal range, and recovery of NKa was correlated to hematopoietic recovery. Our results suggest that deficient NKa is an intrinsic feature of aplastic anemia, and that the circulating cells in this disease are of the pre-NK cell stage.