Current concepts in the pathophysiology and treatment of aplastic anemia

Rapamycin is highly effective in murine models of immune-mediated bone marrow failure

Acquired aplastic anemia, the prototypical bone marrow failure disease, is characterized by pancytopenia and marrow hypoplasia. Most aplastic anemia patients respond to immunosuppressive therapy, usually with anti-thymocyte globulin and cyclosporine, but some relapse on cyclosporine withdrawal or require long-term administration of cyclosporine to maintain blood counts. In this study, we tested efficacy of rapamycin as a new or alternative treatment in mouse models of immune-mediated bone marrow failure. Rapamycin ameliorated pancytopenia, improved bone marrow cellularity, and extended animal survival in a manner comparable to the standard dose of cyclosporine. Rapamycin effectively reduced Th1 inflammatory cytokines interferon-γ and tumor necrosis factor-α, increased the Th2 cytokine interleukin-10, stimulated expansion of functional regulatory T cells, eliminated effector CD8⁺ T cells (notably T cells specific to target cells bearing minor histocompatibility antigen H60), and preserved hematopoietic stem and progenitor cells. Rapamycin, but not cyclosporine, reduced the proportion of memory and effector T cells and maintained a pool of naïve T cells. Cyclosporine increased cytoplasmic nuclear factor of activated T-cells-1 following T-cell receptor stimulation, whereas rapamycin suppressed phosphorylation of two key signaling molecules in the mammalian target of rapamycin pathway, S6 kinase and protein kinase B. In summary, rapamycin was an effective therapy in mouse models of immune-mediated bone marrow failure, acting through different mechanisms to cyclosporine. Its specific expansion of regulatory T cells and elimination of clonogenic CD8⁺ effectors support its potential clinical utility in the treatment of aplastic anemia.

Efficacy and advantages of modified Traditional Chinese Medicine treatments based on "kidney reinforcing" for chronic aplastic anemia: a randomized controlled clinical trial

OBJECTIVE

To compare the efficacy of modified treatments based on "kidney reinforcing" in the management of chronic aplastic anemia (CAA), and explore their advantages and specialties.

METHODS

One hundred and eleven patients with CAA were randomly divided into three groups: kidney reinforcing alone (KA), "kidney reinforcing and Qi tonifying" (KQ), and "kidney reinforcing and blood circulation invigorating" (KC). Normal and positive control groups were also formed. All patients were treated for 6 months (two courses). Hemograms, Traditional Chinese Medicine (TCM) syndrome scores, and therapeutic effects were assessed, and changes in T-lymphocyte subsets, regulatory T cells and cytokines were detected.

RESULTS

The KQ and KC groups had lower TCM syndrome scores than the positive control group after 6 months (P < 0.05). The KQ group had a higher overall efficacy than the positive control group after 3 months (P < 0.05), while platelet counts increased in the KC group after 6 months (P < 0.05). CD3+ T-lymphocyte ratios decreased only in the KQ group, while CD3 + CD4 + CD8 − Tlymphocytes increased only in the KC group after 6 months (P < 0.05). Levels of interferon-γ, tumor necrosis factor tor-α, interleukin (IL)-2 and IL-6 decreased and levels of IL-4 and IL-10 increased in all treated groups after 6 months. Levels of IL-6 in the KQ and KC groups were lower than those in the positive control group (P < 0.05).

CONCLUSION

Treatments based on kidney reinforcing have a rebalancing effect on cytotoxic and T helper cells, and regulate expression of interferon- γ, IL-2, IL-6 and IL-4. KQ may be more effective in treating CAA, and KC may have an advantage in platelet recovery.

Pro-inflammatory effects of the Th1 chemokine CXCL10 in acquired aplastic anaemia

CXCL10/IFN-γ-induced protein 10 (IP-10) and its corresponding receptor CXCR3 have long been considered to be involved in the pathophysiology of type 1 T (Th1) cell-orientated autoimmune diseases. However, the exact role of CXCL10 in the pathogenesis of aplastic anaemia (AA) has not been thoroughly studied. The aim of our study was to evaluate the plasma level of CXCL10 and its effects on CD4⁺ T cell differentiation in AA. In our study, we found that an elevated plasma level of CXCL10 was negatively correlated with platelet, absolute neutrophil and reticulocyte counts, while it was positively correlated with the proportion of lymphocytes in white blood cells in AA patients. To confirm the pro-inflammatory effects of CXCL10 in AA, we isolated CD4⁺ T cells and evaluated the function of CXCL10 in CD4⁺ T cell differentiation. In vitro stimulation experiments further revealed the pro-inflammatory role of CXCL10 in AA, partially by promoting the secretion of interferon (IFN)-γ and IL-17. In addition, CXCL10 significantly skewed CD4⁺ T cell differentiation to Th1 cells and T helper 17 (Th17) cells in AA patients, while it inhibited the differentiation of type 2 T (Th2) cells only in controls. The mRNA expression of transcription factors representative of T cell differentiation was detected by RT-PCR. Consistently, our results showed that after CXCL10 treatment, the expression of T-bet and RORγt was significantly enhanced, while the expression of GATA3 was inhibited. In conclusion, our results indicated that CXCL10, a pro-inflammatory chemokine, might be involved in the abnormal immune response in AA.

Microbe-Induced Inflammatory Signals Triggering Acquired Bone Marrow Failure Syndromes

Acquired bone marrow failure syndromes encompass a unique set of disorders characterized by a reduction in the effective production of mature cells by the bone marrow (BM). In the majority of cases, these syndromes are the result of the immune-mediated destruction of hematopoietic stem cells or their progenitors at various stages of differentiation. Microbial infection has also been associated with hematopoietic stem cell injury and may lead to associated transient or persistent BM failure, and recent evidence has highlighted the potential impact of commensal microbes and their metabolites on hematopoiesis. We summarize the interactions between microorganisms and the host immune system and emphasize how they may impact the development of acquired BM failure.

Outcome of anti-thymocyte immunoglobulin plus cyclosporine A for severe aplastic anaemia with chronic hepatitis B virus infection

The influence of chronic hepatitis B virus (HBV) infection on the efficacy of intensive immunosuppressive treatment (IST) of severe aplastic anaemia (SAA) patients remains unclear. Previous reports on this topic have been mostly case reports or have had a relatively short follow-up. Eight SAA patients carrying chronic HBV infection and 24 matched patients without HBV at a ratio of 1:3 were included in this retrospective analysis. The patients were treated with anti-thymocyte globulin (ATG) and cyclosporine A. Entecavir was or was not administered throughout the IST course to patients with positive or negative HBV-DNA results, respectively. No evident HBV reactivation developed. The overall response was 87.5% by 12 months, and the recurrence rate was 12.5%. There were no significant differences in overall response, overall survival and event-free survival between groups. Entecavir can effectively prevent reactivation of HBV in SAA patients with positive HBV-DNA who received intensive IST. Regular surveillance may be sufficient for HBV-DNA negative patients who should receive antiviral drugs immediately when their HBV-DNA status changes from negative to positive. The prognosis of SAA patients with chronic HBV infection after intensive IST treatment is not worse than those without HBV infection.

[Clinical characteristics of clonal evolution after immunosuppressive therapy in children with severe/very severe aplastic anemia]

OBJECTIVE

To evaluate the clinical characteristics and risk factors of clonal evolution after immunosuppressive therapy (IST) in children with severe/very severe aplastic anemia (SAA/VSAA).

METHODS

The clinical data of 231 children with newly-diagnosed SAA/VSAA who received IST were retrospectively studied. The incidence and risk factors of clonal evolution after IST were analyzed.

RESULTS

The 5-year overall survival rate of the 231 patients was 82.7%. Except for 18 cases of early deaths, 213 patients were evaluated for IST efficacy. Among the 231 patients, cytogenetic abnormalities for at least two chromosome metaphase were detectable in 14 (7.4%) patients, and PNH clones were detectable in either peripheral red blood cells or neutrophils for 95 patients. Among the 213 patients evaluated for IST efficacy, 15 patients experienced clonal evolution after IST. Five patients had PNH and trisomy 8 which were defined as favorable progressions, and ten patients experienced monosomy 7 and MDS/AML as unfavorable progressions. The 5-year accumulative incidence of favorable and unfavorable progression were (2.2±2.2)% and (4.8±3.3)%, respectively. Until the last follow-up, 100% (5/5) of patients with favorable progressions and 50% (5/10) of patients with unfavorable progressions survived. WBC>3.5×10⁹/L, CD3⁺T cell percentage>80%, dosage of antithymocyte globulin >3.0 mg/(kg·d) and no response to IST were related to unfavorable progressions by univariate analysis. Cox multivariate analysis revealed that an increased CD3⁺T cell percentage (>80%) and no response to IST were independent risk factors for unfavorable progressions.

CONCLUSIONS

The children with SAA/VSAA who have an increased CD3⁺T cell percentage at diagnosis or have no response to IST are in high risks of unfavorable progressions.

[Clinical characteristics of clonal evolution after immunosuppressive therapy in children with severe/very severe aplastic anemia]

OBJECTIVE

To evaluate the clinical characteristics and risk factors of clonal evolution after immunosuppressive therapy (IST) in children with severe/very severe aplastic anemia (SAA/VSAA).

METHODS

The clinical data of 231 children with newly-diagnosed SAA/VSAA who received IST were retrospectively studied. The incidence and risk factors of clonal evolution after IST were analyzed.

RESULTS

The 5-year overall survival rate of the 231 patients was 82.7%. Except for 18 cases of early deaths, 213 patients were evaluated for IST efficacy. Among the 231 patients, cytogenetic abnormalities for at least two chromosome metaphase were detectable in 14 (7.4%) patients, and PNH clones were detectable in either peripheral red blood cells or neutrophils for 95 patients. Among the 213 patients evaluated for IST efficacy, 15 patients experienced clonal evolution after IST. Five patients had PNH and trisomy 8 which were defined as favorable progressions, and ten patients experienced monosomy 7 and MDS/AML as unfavorable progressions. The 5-year accumulative incidence of favorable and unfavorable progression were (2.2±2.2)% and (4.8±3.3)%, respectively. Until the last follow-up, 100% (5/5) of patients with favorable progressions and 50% (5/10) of patients with unfavorable progressions survived. WBC>3.5×109/L, CD3+T cell percentage>80%, dosage of antithymocyte globulin >3.0 mg/(kg·d) and no response to IST were related to unfavorable progressions by univariate analysis. Cox multivariate analysis revealed that an increased CD3+T cell percentage (>80%) and no response to IST were independent risk factors for unfavorable progressions.

CONCLUSIONS

The children with SAA/VSAA who have an increased CD3+T cell percentage at diagnosis or have no response to IST are in high risks of unfavorable progressions.

Novel deletion mutation of HLA-B*40:02 gene in acquired aplastic anemia

Despite prevalence of clonal evolution in patients with aplastic anemia (AA), somatic mutation of human leukocyte antigen (HLA) gene is rarely reported. Herein, we reported a case of acquired AA (aAA) harboring a new four-base-pair deletion mutation within exon 4 of HLA-B*40:02 leading to frameshift and premature stop codon. The HLA-B*40:02 mutant allele was detected in the patient's peripheral blood sample not in patient's buccal epithelial cells. The patient received allogenic hematopoietic stem cell transplantation (HSCT) from HLA-matched sibling donor. On day 30 after HSCT, the mutant HLA allele was not detected by high-resolution sequence-based HLA typing. Serial chimerism analyses showed mixed chimeric status indicative of coexisting donor and recipient hematopoietic cells. Our data could provide additional support in view of pathophysiology of aAA that somatic mutation of HLA-B*40:02 allele is one of the possible origin of clonal escape to evade immune attack in patient with aAA.

Effect of Recipient Age and Stem Cell Source on the Association between Donor Telomere Length and Survival after Allogeneic Unrelated Hematopoietic Cell Transplantation for Severe Aplastic Anemia

We previously showed an association between donor leukocyte relative telomere length (RTL) and post-hematopoietic cell transplantation (HCT) survival in patients with severe aplastic anemia (SAA) who received bone marrow grafts at ages <40 years. Here, we tested the generalizability of the prior findings in an independent validation cohort and by recipient age and stem cell source in the combined discovery and validation cohorts. We used monoplex quantitative real-time PCR to measure RTL in: (1) a new SAA validation cohort of 428 patients (age range, .2 to 77 years) with available pretransplantation donor blood samples in the Center for International Blood and Marrow Transplant Research repository, and (2) 278 patients from the original cohort who had sufficient DNA to repeat RTL testing. We used Cox proportional hazard models to calculate hazard ratios (HRs), and 95% confidence intervals (CIs) across categories of donor RTL. Data from the validation cohort showed no association between donor RTL and patient survival, but further analysis identified differences by recipient age and stem cell source as the likely explanation. In patients <40 years, the HR comparing longest with shortest and middle RTL tertiles = .75; 95% CI,  .44 to 1.30 versus HR = 1.05; 95% CI, .59 to 1.89 for patients ≥40 years, P interaction = .37. In bone marrow recipients, the HR = .68; 95% CI, .72 to 1.10 versus HR = 1.29; 95% CI, .64 to 2.62 for peripheral blood stem cell grafts; P interaction = .88. Analyses using data from the 2 cohorts showed a statistically significant survival benefit only in <40-year-old patients receiving bone marrow graft (HR comparing longest and middle RTL tertiles with shortest = .69; 95% CI, .50 to .95, P = .02). The study suggested that the association between donor RTL and post-HCT outcomes in recipients with SAA may vary by recipient age and stem cell source. A larger study is needed to account for multiple comparisons and to further test the generalizability of our findings.

Necroptosis in spontaneously-mutated hematopoietic cells induces autoimmune bone marrow failure in mice

Acquired aplastic anemia is an autoimmune-mediated bone marrow failure syndrome. The mechanism by which such an autoimmune reaction is initiated is unknown. Whether and how the genetic lesions detected in patients cause autoimmune bone marrow failure have not yet been determined. We found that mice with spontaneous deletion of the TGFβ-activated kinase-1 gene in a small subset of hematopoietic cells developed bone marrow failure which resembled the clinical manifestations of acquired aplastic anemia patients. Bone marrow failure in such mice could be reversed by depletion of CD4⁺ T lymphocytes or blocked by knockout of interferon-γ, suggesting a Th1-cell-mediated autoimmune mechanism. The onset and progression of bone marrow failure in such mice were significantly accelerated by the inactivation of tumor necrosis factor-α signaling. Tumor necrosis factor-α restricts autoimmune bone marrow failure by inhibiting type-1 T-cell responses and maintaining the function of myeloid-derived suppressor cells. Furthermore, we determined that necroptosis among a small subset of mutant hematopoietic cells is the cause of autoimmune bone marrow failure because such bone marrow failure can be prevented by deletion of receptor interacting protein kinase-3 Our study suggests a novel mechanism to explain the pathogenesis of autoimmune bone marrow failure.

Eltrombopag for the treatment of aplastic anemia: current perspectives

Aplastic anemia (AA) is a potential life-threatening hematopoietic stem cell (HSC) disorder resulting in cytopenia. The mainstays of treatment for AA are definitive therapy to restore HSCs and supportive measures to ameliorate cytopenia-related complications. The standard definitive therapy is HSC transplantation for young and medically fit patients with suitable donors and immunosuppressive therapy (IST) with antithymocyte globulin and cyclosporine for the remaining patients. A significant proportion of patients are refractory to IST or relapse after IST. Various strategies have been explored in these patients, including second course of antithymocyte globulin, high-dose cyclophosphamide, and alemtuzumab. Eltrombopag, a thrombopoietin mimetic, has recently emerged as an encouraging and promising agent for patients with refractory AA. It has demonstrated efficacy in restoring trilineage hematopoiesis, and this positive effect continues after discontinuation of the drug. There are ongoing clinical trials exploring the role of eltrombopag as a first-line therapy in moderate to severe AA and a combination of eltrombopag with IST in severe AA.

Persistent elevated bone marrow plasma levels of thrombopoietin in patients with aplastic anemia

Acquired aplastic anemia (AA) is an immune-mediated bone marrow (BM) failure syndrome. Plasma thrombopoietin (TPO) levels are elevated in AA patients with reduced blood counts. However, whether elevated TPO can recover to normal level in AA patients in complete remission (CR) after efficient immunosuppressive therapy (IST) is unknown. We measured TPO levels of BM plasma in a large cohort of AA patients with focusing on patients in CR after IST. Our data showed that BM plasma TPO levels were still high in patients who had reached normal blood counts levels for a long time. We speculate that downregulated expression of MPL (TPO receptor) in HSPC (hematopoietic stem and progenitor cells) may be related to the upregulated TPO in AA.

Comparative proteomic analysis of CD34(+) cells in bone marrow between severe aplastic anemia and normal control

Severe aplastic anemia (SAA) is an autoimmune disease with destruction of hematopoietic cells by activated T lymphocytes. However, the precise mechanism of cytotoxicity T cells recognizing and attacking CD34(+) cells remains unclear. Here, we investigated the proteome of CD34(+) cells in SAA patients to further explore the pathogenesis of SAA. CD34(+) cells from 29 SAA patients and 20 health controls were isolated by magnetic activated cell sorting. The protein of CD34(+) cells were examined by iTRAQ labeling combination of multidimensional liquid chromatography and tandem mass spectrometry. A total of 156 differential expression proteins in CD34(+) cells were identified. Compared with health controls, 53 proteins were up-regulated and 103 proteins were down-regulated in SAA patients. Specifically, abnormal expression of proteasome subunits, histone variants, dolichyl-diphosphooligosaccharide-protein glycosyltransferase subunit (DAD1) and ATPase inhibitor, mitochondrial isoform 1 precursor(IF1) may relate to the hyperfunction of immune responses and excessive apoptosis of SAA CD34(+) cells.

Red blood cell alloimmunization in transfused patients with bone marrow failure syndromes

BACKGROUND

Red blood cell (RBC) alloimmunization is a concern for patients who receive multiple or chronic transfusions. Alloimmunization prevalence in transfused patients with bone marrow failure syndrome (BMFS) is unknown. This study aimed to determine physician practice for RBC antigen matching, immunization rates, and antibody specificities in patients with BMFS.

STUDY DESIGN AND METHODS

The clinical records of all patients with BMFS seen at the Children's Hospital of Philadelphia between 2001 and 2015 were reviewed. Immunization rate was determined per 100 units transfused.

RESULTS

ABO/D, C, E, and K (CEK) RBC matching was requested for 21.8% of patients. A total of 3782 RBC units were transfused to 87 patients, of which 2551 (67.5%) were CEK matched and 1231 (32.5%) were ABO/D only matched. The majority of units transfused to patients on a chronic transfusion regimen were CEK matched (89.6% of 2728 units). No anti-C, -E, or -K antibodies formed in any patient during the 14-year study period. Two alloantibodies and two autoantibodies formed, resulting in a rate of 0.05 alloantibodies and 0.05 autoantibodies per 100 units transfused. The prevalence of alloimmunization was 2.3%.

CONCLUSION

The rate and prevalence of RBC alloimmunization were low in patients with BMFS. CEK matching avoided alloimmunization to these antigens in chronically transfused patients.

[A case of myasthenia gravis with transient taste disorders followed by aplastic anemia after thymectomy]

A 45-year-old man was admitted to our hospital because of taste disorders in March 2014. He exhibited cervical muscle weakness and left eye ptosis, which responded to Tensilon test, and was diagnosed with myasthenia gravis (MG). He developed aspiration pneumonia and myasthenic crisis, which was treated with intravenous immunoglobulin and steroid pulse therapy. All symptoms disappeared. Oral administration of prednisolone and tacrolimus was started. Chest CT revealed thymoma and extended thymectomy was performed in May 2014. In December 2014, seven months after the thymectomy, hematological examination showed pancytopenia including severe neutropenia. We diagnosed his illness as aplastic anemia (AA). Cyclosporine therapy with transfusion was administerd and led to reticulocyte count recovery. Since May 2015, hemoglobin recovery reached a blood transfusion free period. To our knowledge, this is the first case report with the patient supposed of relationship among taste disorders, AA and thymoma-associated MG.

Disrupted lymphocyte homeostasis in hepatitis-associated acquired aplastic anemia is associated with short telomeres

Hepatitis‐associated aplastic anemia (HAA) is a variant of acquired aplastic anemia (AA) in which immune‐mediated bone marrow failure (BMF) develops following an acute episode of seronegative hepatitis. Dyskeratosis congenita (DC) is an inherited BMF syndrome characterized by the presence of short telomeres, mucocutaneous abnormalities, and cancer predisposition. While both conditions may cause BMF and hepatic impairment, therapeutic approaches are distinct, making it imperative to establish the correct diagnosis. In clinical practice, lymphocyte telomere lengths (TL) are used as a first‐line screen to rule out inherited telomeropathies before initiating treatment for AA. To evaluate the reliability of TL in the HAA population, we performed a retrospective analysis of TL in 10 consecutively enrolled HAA patients compared to 19 patients with idiopathic AA (IAA). HAA patients had significantly shorter telomeres than IAA patients (P = 0.009), including four patients with TL at or below the 1st percentile for age‐matched controls. HAA patients had no clinical features of DC and did not carry disease‐causing mutations in known genes associated with inherited telomere disorders. Instead, short TLs were significantly correlated with severe lymphopenia and skewed lymphocyte subsets, features characteristic of HAA. Our results indicate the importance of caution in the interpretation of TL measurements in HAA, because, in this patient population, short telomeres have limited specificity. Am. J. Hematol. 91:243–247, 2016. © 2015 The Authors. American Journal of Hematology Published by Wiley Periodicals, Inc.

IFN-γ-mediated hematopoietic cell destruction in murine models of immune-mediated bone marrow failure

Interferon gamma (IFN-γ) has been reported to have both negative and positive activity on hematopoietic cells, adding complexity to the interpretation of its pleiotropic functions. We examined the effects of IFN-γ on murine hematopoietic stem cells (HSCs) and progenitors in vitro and in vivo by using mouse models. IFN-γ treatment expanded bone marrow (BM) c-Kit(+)Sca1(+)Lin(-) (KSL) cell number but reduced BM KLCD150(+) and KLCD150(+)CD48(-) cells. IFN-γ-expanded KSL cells engrafted poorly when tested by competitive repopulation in vivo. KSL, KLCD150(+), and KLCD150(+)CD48(-) cells from IFN-γ-treated animals all showed significant upregulation in Fas expression. When cocultured with activated T cells in vitro, KSL and KLCD150(+) cells from IFN-γ-treated donors showed increased apoptosis relative to those from untreated animals, and infusion of activated CD8 T cells into IFN-γ-injected animals in vivo led to partial elimination of KSL cells. Exposure of BM cells or KSL cells to IFN-γ increased expression of Fas, caspases, and related proapoptotic genes and decreased expression of Ets-1 and other hematopoietic genes. In mouse models of BM failure, mice genetically deficient in IFN-γ receptor expression showed attenuation of immune-mediated marrow destruction, whereas effector lymphocytes from IFN-γ-deficient donors were much less potent in initiating BM damage. We conclude that the activity of IFN-γ on murine hematopoiesis is context dependent. IFN-γ-augmented apoptotic gene expression facilitates destruction of HSCs and progenitors in the presence of activated cytotoxic T cells, as occurs in human BM failure.

Anemia of Central Origin

Hypoproliferative anemia results from the inability of bone marrow to produce adequate numbers of red blood cells. The list of conditions that cause hypoproliferative anemia is long, starting from common etiologies as iron deficiency to rarer diagnoses of constitutional bone marrow failure syndromes. There is no perfect diagnostic algorithm, and clinical data may not always clearly distinguish "normal" from "abnormal", yet it is important for practicing clinicians to recognize each condition so that treatment can be initiated promptly. This review describes diagnostic approaches to hypoproliferative anemia, with particular emphasis on bone marrow failure syndromes.

Association of GSTM1 and GSTT1 deletion polymorphisms with Pakistani aplastic anemia patients and controls and meta-analysis

Interaction of environmental and genetic elements plays a vital role in the pathogenesis of aplastic anemia (AA). Glutathione S-transferase (GST) is a key detoxifying enzyme. Absence or low levels of this enzyme may genetically predispose individuals to AA. GST genes GSTM1 and GSTT1 are polymorphic. The aim of this study was to screen Pakistani AA patients and controls for GSTM1 deletion GSTM0 and GSTT1 deletion GSTT0 and perform meta-analysis using our data and other published data regarding these polymorphisms. DNA samples from 137 patients and 220 controls were screened using multiplex polymerase chain reaction. GSTM0 emerged as susceptible genotype for AA in Pakistan with a percentage frequency of 49.6 % as compared to 30 % in controls with odds ratio (OR) of 2.25, 95 % confidence interval (CI) of 1.4-3.5 and corrected p = 0.006. The meta-analysis showed a significant association between the null genotype GSTT0 and AA in overall analysis with OR of 1.47, 95 % CI of 1.01-2.13 and p value of 0.04 in random effects model. Studies like these could play a role in understanding the underlying path in AA pathogenesis and therefore can help in designing means for prevention, diagnose and treatment.

Acute Myeloid Leukemia With Myelodysplasia-Related Changes

OBJECTIVES

Acute myeloid leukemia with myelodysplasia-related changes (AML-MRC) is a heterogeneous disorder defined by morphologic, genetic, or clinical features. Genetic abnormalities associated with AML-MRC are often associated with adverse prognostic features, and many cases are preceded by a myelodysplastic syndrome (MDS) or a myelodysplastic/myeloproliferative neoplasm.

METHODS

Although the criteria of 20% or more blasts in blood or bone marrow and multilineage dysplasia affecting 50% or more of cells in two or more of the myeloid lineages seem straightforward for AML-MRC, identification of morphologic dysplasia among observers is not always consistent, and there is morphologic overlap with other leukemic disorders such as acute erythroleukemia.

RESULTS

Session 3 of the workshop cases displayed heterogeneity as expected within AML-MRC, yet several cases suggested that recently recognized entities may exist within this category, such as familial MDS/AML predisposition syndromes and rare cases of high-risk AML associated with the cryptic t(5;11)(q35;p15);NUP98-NSD1 that may masquerade as a del(5q). However, most cases of AML-MRC were usually associated with adverse genetic abnormalities, particularly -5/del(5q), -7/del(7q), and/or complex karyotypes.

CONCLUSIONS

Whole-genome sequencing and array studies may identify genetic abnormalities, such as those affecting TP53, which may provide prognostic information.

Effects of the Total Saponins fromDioscorea nipponicaon Immunoregulation in Aplastic Anemia Mice

Dioscorea nipponica Makino, a popular folk medicine, exerts anti-inflammation properties. The present study investigated the therapeutic effect of the total saponins from Dioscorea nipponica Makino (TSDN) on aplastic anemia (AA) and possible immune regulation mechanisms. Using a mouse model of AA, three different doses of TSDN were orally administrated for 14 consecutive days. We first demonstrated that TSDN was found to be effective in alleviating pancytopenia with a hypocellular bone marrow as compared with AA model group. Moreover, gastrogavage administration of a medium dose of TSDN was found to dramatically increase the percentage of CD4+cells in bone marrow nucleated cells (BMNC) and restore the CD4+/CD8+ratio. The pro-inflammatory cytokine concentrations of IL-2 and IFN-γ were significantly decreased, and anti-inflammatory cytokine IL-4 was significantly increased in culture supernatant of BMNC. Further investigations showed that TSDN obviously inhibited Fas–FasL-induced BMNC apoptosis as well as effectively suppressed intracellular apoptosis protein of caspase-3 and -8 expressions. Taken together, these findings suggested that TSDN could alleviate AA by elevating the CD4+/CD8+T-cell ratio, inhibiting inflammatory Th1-cytokines, and exerting anti-apoptosis effects.

Involvement of interleukin-21 in the pathophysiology of aplastic anemia

OBJECTIVE

Recently enhanced T-helper type 17 (Th17) immune responses and deficient CD4(+) CD25(hi) FoxP3(+) regulatory T cells (Tregs) have been reported in acquired aplastic anemia (AA). Interleukin-21 (IL-21), a CD4(+) T-cell-derived proinflammatory cytokine, modulates the balance between Th17 cells and Tregs. However, its role in AA remains unclear.

METHODS

IL-21 gene expression was examined by quantitative real-time PCR. Cytokines in plasma and cell culture supernatants were detected by ELISA. Cytokines-producing T cells and Tregs were evaluated by flow cytometry.

RESULTS

IL-21 mRNA levels in circulating CD4(+) T cells and IL-21 levels in blood plasma were markedly increased in patients with newly diagnosed AA. Moreover, elevated IL-21-producing CD4(+) T cells were accompanied by Th17 cells accumulation and Tregs decrease, and correlated with AA activity. In vitro, IL-21 not only inhibited the expression of FoxP3, but also induced the expression of IL-17 in CD4(+) T cells of AA patients. More importantly, we found that T cells within the bone marrow (BM) of AA patients were in a heightened activation state, which may be related to IL-21.

CONCLUSION

Our data suggested a critical role of IL-21 in breaking immune homeostasis in AA by promoting Th17 cells, activating BM T cells and suppressing Tregs.

The combined use of cytokine-induced killer cells and cyclosporine a for the treatment of aplastic anemia in a mouse model

In this study, we investigated the combined use of cytokine-induced killer (CIK) cells and cyclosporine A (CsA) to treat a mouse model of aplastic anemia (AA). CIK cells were cultured and injected alone or in combination with CsA into mice that had previously been induced into AA by busulfan and mouse interferon-γ (IFN-γ). The CIK cell-treated group had a survival rate of 55%, which was similar to the 60% survival rate observed in the CsA-treated group. The combination group showed a survival rate as high as 90%, while none of the mice in the no-treatment group survived to the end of the experiment. The CIK cells produced multiple cytokines, including several hematopoietic growth factors, which could promote the expansion of mouse bone marrow mononuclear cells in vitro. CsA reduced the proportion of CD4(+) T cells and the level of IFN-γ. The combined CIK cell and CsA treatment exhibited the best curative effect, a finding that might be due to the influence of these factors on both hematopoiesis and immunity. These data suggest that the combination of CIK cells and immunosuppressive therapy might be a candidate therapy for AA in the future.

Association between donor leukocyte telomere length and survival after unrelated allogeneic hematopoietic cell transplantation for severe aplastic anemia

IMPORTANCE

Telomeres protect chromosome ends and are markers of cellular aging and replicative capacity.

OBJECTIVE

To evaluate the association between recipient and donor pretransplant leukocyte telomere length with outcomes after unrelated donor allogeneic hematopoietic cell transplantation (HCT) for patients with severe aplastic anemia.

DESIGN, PARTICIPANTS, AND SETTING

The study included 330 patients (235 acquired, 85 Fanconi anemia, and 10 Diamond-Blackfan anemia) and their unrelated donors who had pre-HCT blood samples and clinical and outcome data available at the Center for International Blood and Marrow Transplant Research. Patients underwent HCT between 1989 and 2007 in 84 centers and were followed-up to March 2013.

EXPOSURES

Recipient and donor pre-HCT leukocyte telomere length classified into long (third tertile) and short (first and second tertiles combined) based on donor telomere length distribution.

MAIN OUTCOMES AND MEASURES

Overall survival, neutrophil recovery, and acute and chronic graft-vs-host disease, as ascertained by transplant centers through regular patient follow-up.

RESULTS

Longer donor leukocyte telomere length was associated with higher survival probability (5-year overall survival, 56%; number at risk, 57; cumulative deaths, 50) than shorter donor leukocyte telomere length (5-year overall survival, 40%; number at risk, 71; cumulative deaths, 128; P = .009). The association remained statistically significant after adjusting for donor age, disease subtype, Karnofsky performance score, graft type, HLA matching, prior aplastic anemia therapy, race/ethnicity, and calendar year of transplant (hazard ratio [HR], 0.61; 95% CI, 0.44-0.86). Similar results were noted in analyses stratified on severe aplastic anemia subtype, recipient age, HLA matching, calendar year of transplant, and conditioning regimen. There was no association between donor telomere length and neutrophil engraftment at 28 days (cumulative incidence, 86% vs 85%; HR, 0.94; 95% CI, 0.73-1.22), acute graft-vs-host disease grades III-IV at 100 days (cumulative incidence, 22% vs 28%; HR, 0.77; 95% CI, 0.48-1.23), or chronic graft-vs-host disease at 1-year (cumulative incidence, 28% vs 30%; HR, 0.81; 95% CI, 0.53-1.24) for long vs short, respectively. Pretransplant leukocyte telomere length in the recipients was not associated with posttransplant survival (HR, 0.91; 95% CI, 0.64-1.30).

CONCLUSIONS AND RELEVANCE

Longer donor leukocyte telomere length was associated with increased 5-year survival in patients who received HCT for severe aplastic anemia. Patient leukocyte telomere length was not associated with survival. The results of this observational study suggest that donor leukocyte telomere length may have a role in long-term posttransplant survival.

Missing Cells: Pathophysiology, Diagnosis, and Management of (Pan)Cytopenia in Childhood

Peripheral blood cytopenia in children can be due to a variety of acquired or inherited diseases. Genetic disorders affecting a single hematopoietic lineage are frequently characterized by typical bone marrow findings, such as lack of progenitors or maturation arrest in congenital neutropenia or a lack of megakaryocytes in congenital amegakaryocytic thrombocytopenia, whereas antibody-mediated diseases such as autoimmune neutropenia are associated with a rather unremarkable bone marrow morphology. By contrast, pancytopenia is frequently associated with a hypocellular bone marrow, and the differential diagnosis includes acquired aplastic anemia, myelodysplastic syndrome, inherited bone marrow failure syndromes such as Fanconi anemia and dyskeratosis congenita, and a variety of immunological disorders including hemophagocytic lymphohistiocytosis. Thorough bone marrow analysis is of special importance for the diagnostic work-up of most patients. Cellularity, cellular composition, and dysplastic signs are the cornerstones of the differential diagnosis. Pancytopenia in the presence of a normo- or hypercellular marrow with dysplastic changes may indicate myelodysplastic syndrome. More challenging for the hematologist is the evaluation of the hypocellular bone marrow. Although aplastic anemia and hypocellular refractory cytopenia of childhood (RCC) can reliably be differentiated on a morphological level, the overlapping pathophysiology remains a significant challenge for the choice of the therapeutic strategy. Furthermore, inherited bone marrow failure syndromes are usually associated with the morphological picture of RCC, and the recognition of these entities is essential as they often present a multisystem disease requiring different diagnostic and therapeutic approaches. This paper gives an overview over the different disease entities presenting with (pan)cytopenia, their pathophysiology, characteristic bone marrow findings, and therapeutic approaches.

Umbilical cord blood transplantation supplemented with the infusion of mesenchymal stem cell for an adolescent patient with severe aplastic anemia: a case report and review of literature

Delayed hematopoietic recovery and increased rate of engraftment failure limit the use of umbilical cord blood transplantation (UCBT). We describe a case of severe aplastic anemia treated by UCBT combined with mesenchymal stem cells. Our case reveals that infusing mesenchymal stem cells early (about 40 days) after UCBT may promote hematopoietic recovery. This experience will guide clinical scientists, especially hematologists, to deal with similar situations and encourage them to widen this strategy.

Immune-mediated bone marrow failure in C57BL/6 mice

We established a model of immune-mediated bone marrow (BM) failure in C57BL/6 (B6) mice with 6.5 G total-body irradiation followed by the infusion of 4-10 × 10(6) lymph node (LN) cells/recipient from Friend leukemia virus B/N (FVB) donors. Forty-three percent of animals succumbed, with surviving animals showing marked declines in blood neutrophils, red blood cells, platelets and total BM cells at 8 to 14 days following LN cell infusion. Lowering the total-body irradiation dose to 5 G or altering the LN source from FVB to BALB/cBy donors failed to produce BM destruction. Affected animals showed significant expansion and activation of CD8 T lymphocytes in both the blood and BM; cytotoxic T cells had elevated Fas ligand expression and were oligoclonal, mainly displaying Vβ7 and Vβ17 T cell receptors. There were significant increases in blood plasma interferon γ and tissue necrosis factor α in affected animals. Chemokine ligands CCL3, CCL4, CCL5, CCL20, CXCL2, and CXCL5 and hematopoietic growth factors G-CSF, M-CSF, GM-CSF, VEGF were also elevated. In B6 mice carrying a Fas gene mutation, BM failure was attenuated when they were infused with FVB LN cells. Our model establishes a useful platform to define the roles of individual genes and their products in immune-mediated BM failure.

Evolution of iron burden in acquired aplastic anemia: a cohort study of more than 3-year follow-up

Acquired aplastic anemia (AA) is the most common condition linked to transfusion dependence. We conducted a cohort study to explore patterns of the dynamic evolution of iron burden, and to identify the risk factors for iron overload (IO) in 550 AA patients. Of the participants, 13 % presented with IO when diagnosed, including 7 % of patients without a history of transfusion and 22 % of those receiving transfusions. Male patients [hazard ratio (HR) = 3.85, 95 % confidence interval (CI) 1.77-8.36], adults (HR = 3.04, 95 % CI 1.21-7.63), and patients with high transfusion burdens (more than eight units; HR = 11.30, 95 % CI 4.45-28.70) experienced a significantly higher risk of IO. Furthermore, we found a sharply increasing risk of IO within the first 2 years, especially in males, patients with large number of lifetime transfusions, and patients not responding to treatment. More interestingly, after transfusion independence, a significant seesaw effect between erythropoiesis and iron burden was not noted until 6 months later, which continued over 3 years. In contrast to female patients, children, and patients with lower transfusion burdens, male subjects, adults, and subjects with high transfusion burdens experienced a pattern of slow decline in iron burden. AA incurred a high risk of progression to IO and showed distinct patterns in the evolution of iron burden. In light of these data, we offer suggestions for decision-making regarding who should undergo iron chelation and when.

Diagnostic and management dilemma of a pancreas-kidney transplant recipient with aplastic anaemia

We report a case of a 57-year-old woman with type I diabetes who had received a simultaneous pancreas-kidney (SPK) transplant maintained on tacrolimus, mycophenolic acid (MPA) and prednisolone. Her renal allograft failed 6 years post-transplant but she continued to have a normal functioning pancreatic allograft. Over the course of 5 years, she developed progressive bone marrow failure with repeat bone marrow aspirates demonstrating an evolution from erythroid hypoplasia to hypocellular marrow and eventual aplastic anaemia despite discontinuation of MPA and reduction of tacrolimus. She was transfusion-dependent and had frequent admissions for sepsis. Despite treatment with antithymocyte globulin and cyclosporine for aplastic anaemia, she developed fatal invasive pulmonary aspergillosis within 3 weeks of treatment. Even though the cause of aplastic anaemia is likely multifactorial, this case highlights the difficulty in balancing the need for versus the risk of ongoing immunosuppression in a SPK transplant recipient who continues to have normal pancreatic graft function.

Allogeneic hematopoietic stem cell transplantation as the first-line treatment option in a patient with severe aplastic anemia without a matched related donor: A case report

The outcomes of matched unrelated donor (MUD) hematopoietic stem cell transplantation (HSCT) and immunosuppressive therapy (IST) in patients with severe aplastic anemia (SAA) remain controversial. The clinical outcome in patients that undergo transplantation following failed IST is typically poorer when compared with patients that initially underwent transplantation. Clinical treatment algorithms have been proposed to determine the management of such patients, and account for individual conditions, personal preferences and prognostic risk factors. The present study reports the promising outcome of a 22-year-old patient exhibiting SAA. The patient underwent peripheral blood stem cell transplantation (PBSCT) from an MUD using a fludarabine-based conditioning regimen and low-dose total body irradiation as an alternative method to first-line IST. The patient achieved rapid bone marrow reconstitution and has been in complete remission for 32 months. The aim of the fludarabine-based conditioning regimen with PBSCT was to improve the patient’s therapeutic outcome and provide a convenient treatment strategy. Furthermore, this regimen extends the application of HSCT to patients who are older or those that are without a matched related donor.

Allogeneic BM transplantation for the treatment of aplastic anemia: current results and expanding donor possibilities

Allogeneic BM transplantation from an HLA-identical sibling donor leads to long-term survival in the majority of patients (>80%). Therefore, survival is no longer the sole concern and attention has to be paid to decreasing the incidence and severity of long-term complications. For patients without a sibling donor, transplantation from a well-matched unrelated donor can be considered after failure of a previous course of immunosuppressive therapy. After transplantation from an HLA-identical sibling donor or from an unrelated one, the use of peripheral blood stem cells must be strongly discouraged because they have been systematically associated with an increased incidence of chronic GVHD compared with the use of BM as a stem cell source, leading to an unacceptably higher risk of treatment-related mortality in this setting. For as yet unknown reasons, the age limit after which transplantation results are less satisfactory remains 40 years of age.