Current concepts in the pathophysiology and treatment of aplastic anemia

Early differential diagnosis of pancytopenia related diseases based on serum surface-enhanced Raman spectroscopy

Pancytopenia is a common blood disorder defined as the decrease of red blood cells, white blood cells and platelets in the peripheral blood. Its genesis mechanism is typically complex and a variety of diseases have been found to be capable of causing pancytopenia, some of which are featured by their high mortality rates. Early judgement on the cause of pancytopenia can benefit timely and appropriate treatment to improve patient survival significantly. In this study, a serum surface-enhanced Raman spectroscopy (SERS) method was explored for the early differential diagnosis of three pancytopenia related diseases, i.e., aplastic anemia (AA), myelodysplastic syndrome (MDS) and spontaneous remission of pancytopenia (SRP), in which the patients with those pancytopenia related diseases at initial stage exhibited same pancytopenia symptom but cannot be conclusively diagnosed through conventional clinical examinations. The SERS spectral analysis results suggested that certain amino acids, protein substances and nucleic acids are expected to be potential biomarkers for their early differential diagnosis. In addition, a diagnostic model was established based on the joint use of partial least squares analysis and linear discriminant analysis (PLS-LDA), and an overall accuracy of 86.67 % was achieved to differentiate those pancytopenia related diseases, even at the time that confirmed diagnosis cannot be made by routine clinical examinations. Therefore, the proposed method has demonstrated great potential for the early differential diagnosis of pancytopenia related diseases, thus it has significant clinical importance for the timely and rational guidance on subsequent treatment to improve patient survival.

Diagnosis and management of acquired aplastic anemia in childhood. Guidelines from the Marrow Failure Study Group of the Pediatric Haemato-Oncology Italian Association (AIEOP)

Acquired aplastic anemia (AA) is a rare heterogeneous disorder characterized by pancytopenia and hypoplastic bone marrow. The incidence is 2-3 per million population per year in the Western world, but 3 times higher in East Asia. Survival in severe aplastic anemia (SAA) has improved significantly due to advances in hematopoietic stem cell transplantation (HSCT), immunosuppressive therapy, biologic agents, and supportive care. In SAA, HSCT from a matched sibling donor (MSD) is the first-line treatment. If a MSD is not available, options include immunosuppressive therapy (IST), matched unrelated donor, or haploidentical HSCT. The purpose of this guideline is to provide health care professionals with clear guidance on the diagnosis and management of pediatric patients with AA. A preliminary evidence-based document prepared by a group of pediatric hematologists of the Bone Marrow Failure Study Group of the Italian Association of Pediatric Hemato-Oncology (AIEOP) was discussed, modified and approved during a series of consensus conferences that started online during COVID 19 and continued in the following years, according to procedures previously validated by the AIEOP Board of Directors.

Predictive value of thyroid function in severe aplastic anemia patients treated with immunosuppressive therapy

To explore the predictive value of thyroid function in severe aplastic anemia (SAA) patients treated with immunosuppressive therapy (IST), 149 SAA patients in our center were enrolled between February 2015 and June 2020 in this study. We assessed the thyroid function of 134 patients without primary thyroid diseases, and discovered that 89 patients were accompanied by abnormal thyroid hormone, especially low triiodothyronine (T3). Patients with higher pretreatment-free T3 (FT3) levels (>5 pmol/L) demonstrated superior response rates at 3 and 6 months after IST compared to those with lower FT3 levels (54.5% vs 35.4%, P = .020; 67.3% vs 46.9%, P = .020). Multivariate analysis indicated that shorter disease duration (≤56 days) and response at 6 months were independent favorable factors of overall survival (relative risk [RR] = 2.66, 95% confidence interval [CI] = 1.03-6.90, P = .040; RR = 30.10, 95% CI = 4.02-225.66, P = .001). The 6-year failure-free survival (FFS) was 53.8% (95% CI = 40.9%-65.1%). Multivariate analysis revealed that patients with a response at 6 months, shorter duration (≤56 days) and receiving rabbit antithymocyte globulin (ATG) had better FFS outcomes than those without a response at 6 months, with a longer duration and receiving porcine ATG (RR = 22.6, 95% CI = 7.9-64.9, P < .001; RR = 2.4, 95% CI = 1.3-4.5, P = .006; RR = 2.5, 95% CI = 1.1-5.8, P = .030). In conclusion, FT3 levels reflect the severity of SAA, and patients with higher FT3 levels (>5 pmol/L) had superior response rates than those with lower ones.

Establishment of reference interval for hemoglobin A1C and other hemoglobin subfractions for healthy Saudi adults

BACKGROUND

The establishment of Reference Intervals (RIs) for Hemoglobin A1C and other hemoglobin subfractions (A1A, A1B, F, LA1C, A0) is of utmost importance in screening, diagnosing, and monitoring diabetes and other hemoglobin abnormalities through the application of high-pressure liquid chromatography (HPLC) technique. Because there are no locally established RIs for these parameters, it is essential to establish RIs specific to the Saudi population to accurately diagnose and monitor diabetic individuals and identify abnormal levels in hemoglobin subfractions.

METHODS

As part of the IFCC global multicenter study of laboratory reference values, a cross-sectional study was conducted in Saudi Arabia. The study involved recruiting a total of 381 healthy adult subjects (>18 years, BMI 28.3 ± 6 kg/m2). Blood samples were analyzed for A1C, biochemical and other immunoassay parameters. The need for RIs based on sex, age, and BMI was determined using the standard deviation ratio (SDR) through a 3-level nested ANOVA.

RESULTS

Based on the threshold of SDR≥0.4, RIs for A1C and other Hb subfractions were not partitioned by sex or BMI, but partitioned by age (<45 & ≥45 years) for A1C, LA1C, A0 and F. Spearman's correlation between glucose, insulin, and C-peptide showed a positive association with different hemoglobin subtractions of A1B, F, A1C, and LA1C. The RIs were obtained by using the parametric method and the latent abnormal values exclusion (LAVE) principle was applied on A1C.

CONCLUSION

This study established RIs for A1C and other Hb subfractions for healthy adult Saudis. Age was found to be an important source of variation for most of the parameters including A1C. These findings will enhance the understanding and clinical decision-making concerning A1C and other hemoglobin subfractions. The elevated upper limit of RIs for A1C reflects the high prevalence of diabetes in the Saudi population specially in those with increased age.

A multicentre ambispective observational study into the incidence and clinical management of aplastic anaemia in Spain (IMAS study)

Aplastic anemia (AA) is a rare, life-threatening hematological disease, with a poorly defined incidence. As the data available on AA varies substantially worldwide, a multicenter, ambispective, observational study was carried out between 2010 and 2019 to assess the incidence, clinical management and survival of AA at seven Spanish hospitals. The incidence of AA was 2.83 per million inhabitants per year, consistent with that reported previously in Europe, with a median age at diagnosis of 61 years-old (range 12-86), and a similar number of males and females. The initial diagnosis was severe or very severe AA in 55.8% of cases and 93.7% required transfusion. The most frequent first line therapy was anti-thymocyte globulin (ATG) plus cyclosporin A (CsA, 44.2%), followed by other CsA-based regimes (46.3%), with hematopoietic stem cell transplantation an infrequent 1st line therapy. The 6-month response rate was 68.2%, which then increased over a median follow-up of 3.9 years. The 5-year overall survival (5OS) was 73.6%, similar in severe (78.6%) and very severe AA patients (74.6%) but lower in moderate AA (MAA) patients (68.4%). The 5OS was 100% in 0-25 year-old patients but dropping to 58.3% in patients ≥ 60 years-old. At the last contact, 75.8% of the patients were alive. In conclusion, the incidence, characteristics and management of AA in our study are consistent with that reported previously. In terms of survival, although the global long-term OS rate was good, there is room for improvement, particularly in older patients. Finally, what appears to be a worse long-term survival of MAA patients, as reported previously, reinforces the importance of not underestimating this condition when diagnosed as MAA.

The role of TIM3+ NK and TIM3- NK cells in the immune pathogenesis of severe aplastic anemia

Background

Natural killer (NK) cells play important immunoregulatory roles in the immune pathogenesis of severe aplastic anemia (SAA). Our previous research showed that SAA caused a decrease in T cell immunoglobulin mucin-3 (TIM3) expression on NK cells. Here we investigated the expression of surface receptors, and the cytotoxicity of peripheral TIM3+ NK and TIM3- NK cells in patients with SAA.

Methods

The expressions of surface receptors and cytoplasmic protein of TIM3+ NK and TIM3- NK cells from peripheral blood were detected by FCM. The functions of mDCs, and apoptosis rate of K562 cells after co-culture with TIM3+ NK and TIM3- NK cells were maesured by FCM. Westren-blot was used to detect the changes of TIM3+ NK and TIM3- NK signaling pathway proteins (AKT, P-AKT) and compare the functional activity of the two groups.

Results

Activating receptors NKG2D and Granzyme B were higher, while inhibiting receptors NKG2A, CD158a and CD158b were lower on TIM3- NK cells compared with TIM3+ NK cells in patients with SAA. In SAA, the expression of CD80 and CD86 on mDCs (Myeloid dendritic cells) was significantly decreased after incubation with TIM3- NK cells. The apoptosis rate (AR) of K562 cells was significantly increased after being incubated with TIM3- NK cells in SAA. The level of signal pathway protein AKT of TIM3- NK cells in SAA was similar to that of TIM3+ NK cells, and the levels of P-AKT and P-AKT/AKT ratio of TIM3- NK cells were significantly higher than those of TIM3+ NK cells.

Conclusions

Therefore, TIM3 exerts its inhibitory effect on NK cells and participates in the immune pathogenesis of SAA. Low expression of TIM3 contributes to the enhancement of NK cell activity which in turn inhibits the immune activation state of SAA and improves the disease state. Our research may aid the development of new therapeutic strategies based on TIM3-NK cells infusion for the treatment of SAA.

Efficacy and safety of avatrombopag in combination with immunosuppressive therapy in treatment-naïve and relapsed/refractory severe aplastic anaemia: protocol for the DIAAMOND-Ava-FIRST and DIAAMOND-Ava-NEXT Bayesian Optimal Phase II trials

INTRODUCTION

Immunosuppressive therapy (IST) with antithymocyte globulin (ATG) and ciclosporin is standard of care for patients with severe aplastic anaemia (sAA) not eligible or suitable for allogeneic stem cell transplant. While patients respond to IST, few achieve complete responses and a significant proportion are refractory or relapse. The addition of eltrombopag, a thrombopoietin-receptor agonist (TPO-A), to IST has been shown to improve haematological responses in sAA. Avatrombopag is a second-generation TPO-A with potential advantages over eltrombopag. However, to date avatrombopag has not been studied in sAA.

METHODS AND ANALYSIS

Investigator-initiated, single-arm registry-based Bayesian Optimal Phase II trial of avatrombopag conducted in two cohorts, patients with untreated sAA (FIRST cohort) and in patients with sAA that has relapsed or is refractory to IST (NEXT cohort). In the FIRST cohort, participants receive IST (equine ATG and ciclosporin) plus avatrombopag from day 1 until day 180 at 60 mg oral daily, with dose adjusted according to platelet count. Participants in the NEXT cohort receive avatrombopag at 60 mg oral daily from day 1 until day 180, with or without additional IST at the discretion of the treating clinician.For each cohort, two primary endpoints (haematological response and acquired clonal evolution) are jointly monitored and the trial reviewed at each interim analysis where a 'go/no-go' decision is made by evaluating the posterior probability of the events of interests.

ETHICS AND DISSEMINATION

The trial has received ethics approval (Monash Health RES-18-0000707A). The trial conduct will comply with ICH-GCP and all applicable regulatory requirements. The results of the trial will be submitted to a peer-review journal for publication.

TRIAL REGISTRATION NUMBER

ACTRN12619001042134, ACTRN12619001043123.

Irisin protected hemopoietic stem cells and improved outcome of severe bone marrow failure

Acquired aplastic anemia (AA) is a bone marrow failure (BMF) disease, characterized by fatty bone marrow (BM) and BM hypocellularity resulted from auto-immune dysregulated T cells-mediated destruction of BM haemopoietic stem cells (HPSC). The objective of this study was to investigate potential therapeutic effect of irisin, a molecule involved in adipose tissue transition, on AA mouse model. Our results showed that the concentration of irisin in serum was lower in AA patients than in healthy controls, suggesting a role of irisin in the pathogenesis of AA. In the AA mice, irisin administration prolonged the survival rate, prevented or attenuated peripheral pancytopenia, and preserved HPSC in the BM. Moreover, irisin also markedly reduced BM adipogenesis. In vitro results showed that irisin increased both cell proliferation and colony numbers of HPSC. Furthermore, our results demonstrated that irisin upregulated the expression of mitochondrial ATPase Inhibitory Factor 1 (IF1) in HPSC, inhibited the activation of mitochondrial fission protein (DRP1) and enhanced aerobic glycolysis. Taken together, our findings indicate novel roles of irisin in the pathogenesis of AA, and in the protection of HPSC through stimulation of proliferation and regulation of mitochondria function, which provides a proof-of-concept for the application of irisin in AA therapy.

All Roads Lead to Interferon-γ: From Known to Untraveled Pathways in Acquired Aplastic Anemia

Bone marrow failure (BMF) syndromes are a heterogeneous group of benign hematological conditions with common clinical features including reduced bone marrow cellularity and peripheral blood cytopenias. Acquired aplastic anemia (AA) is caused by T helper(Th)1-mediated immune responses and cytotoxic CD8+ T cell-mediated autologous immune attacks against hematopoietic stem and progenitor cells (HSPCs). Interferon-γ (IFNγ), tumor necrosis factor-α, and Fas-ligand are historically linked to AA pathogenesis because they drive Th1 and cytotoxic T cell-mediated responses and can directly induce HSPC apoptosis and differentiation block. The use of omics technologies has amplified the amount of data at the single-cell level, and knowledge on AA, and new scenarios, have been opened on "old" point of view. In this review, we summarize the current state-of-art of the pathogenic role of IFNγ in AA from initial findings to novel evidence, such as the involvement of the HIF-1α pathway, and how this knowledge can be translated in clinical practice.

Repair of dysfunctional bone marrow endothelial cells alleviates aplastic anemia

Aplastic anemia (AA) is a life-threatening disease characterized by bone marrow (BM) failure and pancytopenia. As an important component of the BM microenvironment, endothelial cells (ECs) play a crucial role in supporting hematopoiesis and regulating immunity. However, whether impaired BM ECs are involved in the occurrence of AA and whether repairing BM ECs could improve hematopoiesis and immune status in AA remain unknown. In this study, a classical AA mouse model and VE-cadherin blocking antibody that could antagonize the function of ECs were used to validate the role of BM ECs in the occurrence of AA. N-acetyl-L-cysteine (NAC, a reactive oxygen species scavenger) or exogenous EC infusion was administered to AA mice. Furthermore, the frequency and functions of BM ECs from AA patients and healthy donors were evaluated. BM ECs from AA patients were treated with NAC in vitro, and then the functions of BM ECs were evaluated. We found that BM ECs were significantly decreased and damaged in AA mice. Hematopoietic failure and immune imbalance became more severe when the function of BM ECs was antagonized, whereas NAC or EC infusion improved hematopoietic and immunological status by repairing BM ECs in AA mice. Consistently, BM ECs in AA patients were decreased and dysfunctional. Furthermore, dysfunctional BM ECs in AA patients led to their impaired ability to support hematopoiesis and dysregulate T cell differentiation toward proinflammatory phenotypes, which could be repaired by NAC in vitro. The reactive oxygen species pathway was activated, and hematopoiesis- and immune-related signaling pathways were enriched in BM ECs of AA patients. In conclusion, our data indicate that dysfunctional BM ECs with impaired hematopoiesis-supporting and immunomodulatory abilities are involved in the occurrence of AA, suggesting that repairing dysfunctional BM ECs may be a potential therapeutic approach for AA patients.

Indigenous antithymocyte globulin-equine to treat aplastic anaemia in adults: a case series from two centres in northeast India

BACKGROUND

Immunosuppressive therapy is the standard management of adults with aplastic anaemia. Antithymocyte globulin is used as first-line treatment of patients not eligible for bone marrow transplantation. This being a rare disease, available evidence in India is scarce. This study aimed to present experience in treating adult aplastic anaemia patients by immunosuppressive therapy using antithymocyte globulin-equine (Thymogam) in two tertiary care centres of northeast India.

METHODS

This case series was conducted at the Health city hospital, Guwahati, and Excel Care Hospital, Guwahati from 2018 to 2020. Eighteen adult aplastic anaemia patients who were treated by immunosuppressive therapy with antithymocyte globulin-equine (Thymogam) and followed up for two years were included. Treatment response and relapse are described.

RESULTS

All the 18 patients, (14 severe, four very severe) were uniformly treated with immunosuppressive therapy (Thymogam 40 mg/kg/d for four days with oral Cyclosporine from Day-1). Cyclosporin A was used as a concomitant drug in 94.44 % of the patients. At two years of follow up, 66.7 % showed a response and the mortality rate was 11.1 %.

CONCLUSION

The results of this case series substantiate the effectiveness of immunosuppressive therapy with a low-cost preparation of horse antithymocyte globulin (Thymogam) along with cyclosporin A in the management of aplastic anaemia patients not suitable for bone marrow transplantation.

Rehmannia Glutinosa Polysaccharide Regulates Bone Marrow Microenvironment via HIF-1α/NF-κB Signaling Pathway in Aplastic Anemia Mice

Aplastic anemia (AA), a rare disorder, is associated with bone marrow microenvironment (BMM). Presently, AA treatment is of great difficulty. This study aimed to explore the mechanism of action of Rehmannia glutinosa polysaccharide (RGP) in AA. Busulfan was used to induce AA in BALB/c mice; blood cell count and Ray's Giemsa staining were used to assess the severity of hematopoietic failure; HE was performed to assess the pathological state of the marrow cavity; ELISA was performed to assess IL-4, IL-10, IL-6, IL-12, IL-1β, TNF-α, MCP-1, VEGF, and EPO; and WB was performed to evaluate the effects of RGP on the HIF-1α/NF-κB signaling. Significant downregulation of hemocyte levels in the blood and nucleated cells in the bone marrow was reversed by RGP and Cyclosporine A (CA). Compared with the AA group, dilating blood sinusoids, inflammation, hematopoiesis, decreased bone marrow cells and megakaryocytes were alleviated by RGP and CA, and the HIF-1α/NF-κB signaling was inhibited too. Notably, RGP was more effective when used in combination with CA. In this study, we established a relationship between BMM and the HIF-1α/NF-κB signaling pathway and found that RGP regulates BMM by suppressing the activation of the HIF-1α/NF-κB signaling. Thus, RGP exerts a pharmacological effect on AA.

Alemtuzumab in relapsed immune severe aplastic anemia: Long-term results of a phase II study

Immune severe aplastic anemia (SAA) is characterized by pancytopenia and immune-mediated bone marrow destruction. SAA may be treated with hematopoietic stem cell transplantation (HSCT) or immunosuppressive therapy (IST). However, 30% of patients treated with IST relapse. We previously reported a clinical trial of alemtuzumab in which more than half of 25 relapsed SAA patients (56%) responded hematologically. Here, we present long-term results of a total of 42 patients. Participants with SAA who had previously completed antithymocyte globulin (ATG)-based IST, but had relapsed, were enrolled on this study. Alemtuzumab was administered intravenously (IV) (n = 28) or subcutaneously (SC) (n = 14). The primary endpoint was hematologic response at 6 months. Secondary endpoints included relapse, clonal evolution, and survival. This trial was registered at clinicaltrials.gov (NCT00195624). Patients were enrolled over 9 years, with median follow-up of 6 years. Median age was 32 years, with 57% being female. At 6 months, 18 patients (43%) achieved response; 15 (54%) of those who received IV compared with 3 (21%) who received SC therapy. Six patients (14%) had durable long-term response without need for subsequent AA-directed therapy or HSCT at last follow-up. Nine patients had clonal evolution, with high-risk evolution occurring in 6. Overall survival was 67% at median follow-up of 6 years. Prolonged iatrogenic immunosuppression was observed as long as 2 years after alemtuzumab administration. Alemtuzumab induces responses in relapsed SAA, some of which are durable long-term. However, immunosuppression can persist for years, requiring long-term monitoring.

Evolutionary landscape of clonal hematopoiesis in 3,359 individuals from the general population

Knowledge about evolution of clonal hematopoiesis, which may drive malignant progression, is crucial for clinical decision-making. We investigated the landscape of clonal evolution by error-corrected sequencing on 7,045 sequential samples from 3,359 individuals in the prospective population-based Lifelines cohort, with a special focus on cytosis and cytopenia. Spliceosome (SRSF2/U2AF1/SF3B1) and JAK2 mutated clones show highest growth rates over a median 3.6-year period, while clone sizes for DNMT3A and TP53 increase only marginally, independent of cytosis or cytopenia. Nevertheless, large differences are observed between individuals carrying the same mutation, indicative of modulation by non-mutation-related factors. Clonal expansion is not dependent on classical cancer risk factors (e.g., smoking). Risk for incident myeloid malignancy diagnosis is highest for JAK2, spliceosome, or TP53 mutations and absent for DNMT3A, and it is mostly preceded by cytosis or cytopenia. The results provide important insight into high-risk evolutionary patterns to guide monitoring of "CHIP" and "CCUS."

Epigenetic regulation by ASXL1 in myeloid malignancies

Myeloid malignancies are clonal hematopoietic disorders that are comprised of a spectrum of genetically heterogeneous disorders, including myelodysplastic syndromes (MDS), myeloproliferative neoplasms (MPN), chronic myelomonocytic leukemia (CMML), and acute myeloid leukemia (AML). Myeloid malignancies are characterized by excessive proliferation, abnormal self-renewal, and/or differentiation defects of hematopoietic stem cells (HSCs) and myeloid progenitor cells hematopoietic stem/progenitor cells (HSPCs). Myeloid malignancies can be caused by genetic and epigenetic alterations that provoke key cellular functions, such as self-renewal, proliferation, biased lineage commitment, and differentiation. Advances in next-generation sequencing led to the identification of multiple mutations in myeloid neoplasms, and many new gene mutations were identified as key factors in driving the pathogenesis of myeloid malignancies. The polycomb protein ASXL1 was identified to be frequently mutated in all forms of myeloid malignancies, with mutational frequencies of 20%, 43%, 10%, and 20% in MDS, CMML, MPN, and AML, respectively. Significantly, ASXL1 mutations are associated with a poor prognosis in all forms of myeloid malignancies. The fact that ASXL1 mutations are associated with poor prognosis in patients with CMML, MDS, and AML, points to the possibility that ASXL1 mutation is a key factor in the development of myeloid malignancies. This review summarizes the recent advances in understanding myeloid malignancies with a specific focus on ASXL1 mutations.

Panaxadiol saponin ameliorates ferroptosis in iron-overload aplastic anemia mice and Meg-01 cells by activating Nrf2/HO-1 and PI3K/AKT/mTOR signaling pathway

Panaxadiol saponin (PND) is a latent targeted drug for the treatment of aplastic anemia (AA). In this study, we examined the effects of PND on ferroptosis in iron-overload AA and Meg-01 cells. We utilized RNA-seq to analyze differentially expressed genes in iron-induced Meg-01 cells treated with PND. The effects of PND or combined with deferasirox (DFS) on iron deposition, labile iron pool (LIP), several ferroptosis events, apoptosis, mitochondrial structure, as well as ferroptosis-, Nrf2/HO-1-, and PI3K/AKT/mTOR pathway-related markers in iron-induced Meg-01 cells were examined by Prussian-blue staining, flow cytometer, ELISA, Hoechst 33342 staining, transmission electron microscope, and Western blot assays, respectively. Additionally, an AA mice model with iron overload was established. Then, the blood routine was assessed, and the number of bone marrow-derived mononuclear cells (BMMNCs) in mice was counted. Also, serum iron, ferroptosis events, apoptosis, histology, T lymphocyte percentage, ferroptosis-, Nrf2/HO-1-, and PI3K/AKT/mTOR signaling-related targets in primary megakaryocytes of AA mice with iron overload were assessed by commercial kits, TUNEL staining, hematoxylin and eosin (H&E) staining, Prussian blue staining, flow cytometer, and qRT-PCR analysis, respectively. PND suppressed iron-triggered iron overload, and apoptosis, and ameliorated mitochondrial morphology in Meg-01 cells. Importantly, PND ameliorated ferroptosis-, Nrf2/HO-1-, and PI3K/AKT/mTOR signaling-related marker expressions in iron-induced Meg-01 cells or primary megakaryocytes of AA mice with iron overload. Moreover, PND ameliorated body weight, peripheral blood cell counts, the number of BMMNCs, and histological injury in the iron-overload AA mice. Also, PND improved the percentage of T lymphocytes in the iron-overload AA mice. PND attenuates ferroptosis against iron-overload AA mice and Meg-01 cells via activating Nrf2/HO-1 and PI3K/AKT/mTOR pathway and is a promising novel therapeutic candidate for AA.

Molecular landscape of immune pressure and escape in aplastic anemia

Idiopathic aplastic anemia (IAA) pathophysiology is dominated by autoreactivity of human leukocyte antigen (HLA)-restricted T-cells against antigens presented by hematopoietic stem and progenitor cells (HSPCs). Expansion of PIGA and HLA class I mutant HSPCs have been linked to immune evasion from T-cell mediated pressures. We hypothesized that in analogy with antitumor immunity, the pathophysiological cascade of immune escape in IAA is initiated by immunoediting pressures and culminates with mechanisms of clonal evolution characterized by hits in immune recognition and response genes. To that end, we studied the genetic and transcriptomic make-up of the antigen presentation complexes in a large cohort of patients with IAA and paroxysmal nocturnal hemoglobinuria (PNH) by using single-cell RNA, high throughput DNA sequencing and single nucleotide polymorphism (SNP)-array platforms. At disease onset, HSPCs displayed activation of selected HLA class I and II-restricted mechanisms, without extensive inhibition of immune checkpoint apparatus. Using a newly implemented bioinformatic framework we found that not only class I but also class II genes were often impaired by acquisition of genetic aberrations. We also demonstrated the presence of novel somatic alterations in immune genes possibly contributing to the evasion from the autoimmune T-cells. In contrast, these hits were absent in myeloid neoplasia. These aberrations were not mutually exclusive with PNH and did not correlate with the accumulation of myeloid-driver hits. Our findings shed light on the mechanisms of immune activation and escape in IAA and define alternative modes of clonal hematopoiesis.

Outcomes and risk factors of hemorrhagic cystitis in pediatric allogeneic hematopoietic stem cell transplantation recipients using different graft source and condition with severe aplastic anemia

BACKGROUND

Hemorrhagic cystitis (HC) is a severe complication of allo-HSCT, characterized by irritative symptoms of the urinary tract and a higher morbidity rate. The risk factors and prognosis of HC are still unclear.

OBJECTIVE

The objective of this study is to identify risk factors and outcomes to improve treatment in pediatric SAA patients undergoing HSCTs in the Children's Hospital of Soochow University.

METHODS

A total of 97 SAA patients as a cohort were enrolled from 2010 to 2019 in the Children's Hospital of Soochow University and a number of factors related to HC and outcomes were analysed. In all transplants (except UCBT), patients received a combination of G-CSF stimulated bone marrow (BM) and peripheral blood stem cell (PBSC). The minimum number of CD34 + cells is 5 × 10⁶ cells/kg.

RESULTS

Mononuclear cells dose (MNC, cut off: 8.53 × 10⁸/kg) and grade II-IV acute graft versus host disease (aGVHD) were identified as independent risk factors for HC. Patients without HC had better overall survival (OS) than with HC (No HC: 98.6%±1.4% vs HC: 87.4% ± 6.8%, p = 0.03).

CONCLUSION

We concluded that aGVHD and MNC dose in graft might play an important role in the development of HC in pediatric SAA patients undergoing allo-HSCT. HC is also a key complication affecting the prognosis of children with SAA after allo-HSCT.

What is responsible for acute myocardial infarction in combination with aplastic anemia? A case report and literature review

BACKGROUND

Aplastic anemia (AA) complicated with myocardial infarction (MI) is rare and associated with poor prognosis. Here, we present a case of AA with recurrent acute MI (AMI) in a patient treated with cyclosporine A (CsA) and stanozolol. In this patient, we suspect the long-term use of medication linked to platelets hyperfunction.

CASE SUMMARY

In 2017, a 45-year-old man was rushed to the emergency department of China-Japan Union Hospital due to precordial pain for 5 h. Based on his symptoms, medical history, blood tests, and findings from coronary angiography (CAG), the patient was diagnosed with acute anterior wall, ST-segment elevated MI, Killip II grade, AA, and dyslipidemia. In 2021, the patient was readmitted to the hospital for 2 h due to chest pain. Because the patient’s platelet count was 30 × 10⁹/L and he had severe thrombocytopenia, we performed CAG following platelet transfusion. Optical coherence tomography revealed lipid plaque and thrombus mass in his right coronary artery. The antithrombotic approach was adjusted to employ only anticoagulants (factor Xa inhibitors) and adenosine diphosphate inhibitors (clopidogrel) after assessing the risk of bleeding/thrombotic events. Long-term follow-up revealed that the patient had made a good recovery.

CONCLUSION

Patients with AA should be closely monitored for the risk of thrombosis and cardiovascular events, particularly when taking stanozolol or CsA for an extended period of time.

Aplastic Anemia as a Roadmap for Bone Marrow Failure: An Overview and a Clinical Workflow

In recent years, it has become increasingly apparent that bone marrow (BM) failures and myeloid malignancy predisposition syndromes are characterized by a wide phenotypic spectrum and that these diseases must be considered in the differential diagnosis of children and adults with unexplained hematopoiesis defects. Clinically, hypocellular BM failure still represents a challenge in pathobiology-guided treatment. There are three fundamental topics that emerged from our review of the existing data. An exogenous stressor, an immune defect, and a constitutional genetic defect fuel a vicious cycle of hematopoietic stem cells, immune niches, and stroma compartments. A wide phenotypic spectrum exists for inherited and acquired BM failures and predispositions to myeloid malignancies. In order to effectively manage patients, it is crucial to establish the right diagnosis. New theragnostic windows can be revealed by exploring BM failure pathomechanisms.

Medication Regularity of Traditional Chinese Medicine in the Treatment of Aplastic Anemia Based on Data Mining

Objective

Aplastic anemia (AA) is an uncommon disease, characterized by pancytopenia and hypocellular bone marrow, but it is common in the blood system. The medication rules of traditional Chinese medicine (TCM) in the treatment of AA are not clear, for which it is worth exploring the medication rules by data mining methods.

Methods

This study used SPSS Modeler 18.0 and SPSS statistics to analyze the cases of AA from Zhejiang Provincial Hospital of Chinese Medicine (ZJHCM) from March 1, 2019, to March 1, 2022. Data mining methods, including frequency analysis, cluster analysis, and association rule learning, were performed in order to explore the medication rules for AA.

Results

(1) A total of 859 prescriptions, which met the inclusion criteria, consisted of 255 herbs. In descending order of the frequency of herbal medicine, we have Danggui, Huangqi, Shudihuang, Fuling, Gancao, Shanyao, Shanzhuyu, Baizhu, Dangshen, and Xianhecao. (2) Frequency analysis of herb properties: the Four Qi of 255 kinds of TCMs are mainly warm and neutral medicines. The Five Flavors are mainly sweet medicines, followed by bitter medicines. The main meridians are the liver, spleen, and kidney. (3) Clustering of medications: TCMs with the top 20 frequencies are classified into 9 groups by cluster analysis. (4) Association rule analysis of high-frequency herbs: using the Apriori algorithm, the results showed that there were 3 herb pairs with support of over 0.3 and 12 herb pairs with confidence above 0.85.

Conclusion

The basic pathogenesis of AA (Sui Lao) is spleen and kidney essence deficiency, Qi deficiency, and blood stasis. The main herbs have warm and neutral properties, sweet tastes, and liver, spleen, and kidney meridian tropisms, whose purpose is to tonify the kidney and invigorate the spleen, tonify Qi, and promote blood circulation.

Monocytic myeloid-derived suppressive cells mitigate over-adipogenesis of bone marrow microenvironment in aplastic anemia by inhibiting CD8+ T cells

Aplastic anemia (AA) is a blood disorder resulted from over-activated T-cell related hematopoietic failure, with the characterization of hypocellularity and enhanced adipogenic differentiation of mesenchymal stroma cells (MSCs) in bone marrow (BM). However, little is known about the relationship between immune imbalance and polarized adipogenic abnormity of BM microenvironment in this disease entity. In the present study, we differentiated BM-MSCs into osteoblastic or adipogenic lineages to mimic the osteo-adipogenic differentiation. Activated CD8⁺ T cells and interferon-γ (IFN-γ) were found to stimulate adipogenesis of BM-MSCs either in vitro or in vivo of AA mouse model. Interestingly, myeloid-derived suppressive cells (MDSCs), one of the immune-regulating populations, were decreased within BM of AA mice. We found that it was not CD11b⁺Ly6G⁺Ly6C^- granulocytic-MDSCs (gMDSCs) but CD11b⁺Ly6G^-Ly6C⁺ monocytic-MDSCs (mMDSCs) inhibiting both T cell proliferation and IFN-γ production via inducible nitric oxide synthetase (iNOS) pathway. Single-cell RNA-sequencing (scRNA-seq) of AA- and mMDSCs-treated murine BM cells revealed that mMDSCs transfusion could reconstitute BM hematopoietic progenitors by inhibiting T cells population and signature cytokines and decreasing immature Adipo-Cxcl12-abundant reticular cells within BM. Multi-injection of mMDSCs into AA mice reduced intra-BM T cells infiltration and suppressed BM adipogenesis, which subsequently restored the intra-BM immune balance and eventually prevented pancytopenia and hypo-hematopoiesis. In conclusion, adoptive transfusion of mMDSCs might be a novel immune-regulating strategy to treat AA, accounting for not only restoring the intra-BM immune balance but also improving stroma's multi-differentiating microenvironment.

Icariin protects bone marrow mesenchymal stem cells in aplastic anemia by targeting MAPK pathway

BACKGROUND

Icariin, the main pharmacological active flavonoid extracted from Epimedi herba, can regulate cellular processes in diverse diseases. The aim of this study was to explore the effects and mechanisms of icariin on proliferation and adipogenesis of bone marrow mesenchymal stem cells (BMSCs) in aplastic anemia (AA).

METHODS AND RESULTS

Bone marrow mesenchymal stem cells were isolated from posterior tibias and femurs of AA rats that were induced by benzene and cyclophosphamide and gavaged with icariin. The isolated BMSCs were characterized morphologically and immunologically by positive markers (CD29 and CD90) and negative markers (CD34 and CD45). CCK-8 assay was performed to examine the BMSCs proliferation. Cell apoptosis and cell cycle were detected by flow cytometry. Oil red O staining was carried out to evaluate the adipogenesis of BMSCs. The mRNA expression of PPARγ, C/EBP-α, and FABP4 was measured by qRT-PCR. The protein levels of p-p38/p38, p-JNK/JNK, p-ERK/ERK, PPARγ, C/EBP-α, and FABP4 were detected using Western blotting. Icariin promoted the proliferation of BMSCs from AA rats in a dose-dependent manner. The protein levels of p-p38/p38, p-JNK/JNK, and p-ERK/ERK were downregulated in BMSCs from AA rats after icariin treatment. Icariin inhibited the apoptosis and arrested cell cycle at G/S phase of BMSCs from AA rats. The adipogenesis of BMSCs from AA rats was also suppressed after icariin treatment. However, the effects of icariin on BMSCs were weakened by p38 agonist addition.

CONCLUSIONS

Icariin promoted the proliferation and inhibited the apoptosis and adipogenesis of BMSCs in AA by suppressing MAPK pathway.

A multicentre trial of intensive immunosuppressive therapy combined with umbilical cord blood for the treatment of severe aplastic anaemia

Immunosuppressive therapy (IST) is an effective treatment regimen for severe aplastic anaemia (SAA) patients without HLA-identical donors. This study further compared the outcomes between IST and IIST-UCB in SAA on the basis of research shown that IST combined with umbilical cord blood infusion (IIST-UCB) treated effectively. A total of 123 patients from 11 hospitals in China were enrolled. Sixty-nine patients in IIST-UCB group were treated with ATG + CsA + CTX combined with cord blood, while 54 patients in IST group with ATG + CsA. The overall remission rates (ORRs), complete remission (CR) rates and partial response (PR) rates of IIST-UCB group and IST group at 3 months were 69.67% vs 51.85% (P = .045), 21.74% vs 3.7% (P = .004) and 47.83% vs 48.15% (P = .972), respectively. After 6 months of treatment, they were 76.81% vs 57.41% (P = .022), 37.68% vs 11.11% (P = .001) and 39.13% vs 46.30% (P = .425), respectively. After 1 year of treatment, they were 85.51% vs 61.11% (P = .002), 59.42% vs 25.93% (P = .000) and 26.09% vs 35.19% (P = .275), respectively. The ORRs and CR rates of IIST-UCB group were both significantly higher than IST group after 3 months, 6 months and 1 year of treatment. The neutrophil granulocyte, platelet and haemoglobin recovery times of IIST-UCB group were significantly shorter than IST group. Compared with standard IST, IIST-UCB as an effective therapy for SAA patients without HLA-identical donors accelerated the haematopoietic reconstitution, resulting in higher early CR rates.

HLA-G-ILT2 interaction contributes to suppression of bone marrow B cell proliferation in acquired aplastic anemia

Acquired aplastic anemia (AA) is an autoimmune disease characterized by hematopoietic stem and progenitor cell destruction in bone marrow. The non-classic human leukocyte class I antigen (HLA-) G interacts with multiple cell subsets, such as T cells and B cells. HLA-G exerts powerful immune suppression by binding with its receptors, immunoglobulin-like transcripts (ILTs). Here, we compared 46 AA patients and 28 healthy controls. Soluble HLA-G levels in bone marrow supernatants from AA patients were higher than controls. The proportion of bone marrow B cells was decreased and the ILT2-expressing cells among CD19⁺ cells were increased in AA patients. In addition, the percentage of mature B cells among marrow B cells was increased in AA patient, while the percentage of pro-B plus pre-B cells was decreased. More immature B cells and pro-B plus pre-B cells expressed ILT2 in AA patients than in controls, while mature B cells expressing ILT2 did not differ significantly. Functional studies demonstrated that high-level soluble HLA-G inhibited bone marrow B cell proliferation by interacting with ILT2 in AA, and was blocked by anti-HLA-G and anti-ILT2 monoclonal antibodies. Together, these results suggest that the abnormal decrease of pro-B plus pre-B cells in AA patients was related to the enhanced suppression by the excess HLA-G and ILT2 proteins. Therapeutic blockade of the HLA-G-ILT2 interaction may help to normalize bone marrow B cell proliferation.

Comparable Outcomes and Health-Related Quality of Life for Severe Aplastic Anemia: Haploidentical Combined With a Single Cord Blood Unit vs Matched Related Transplants

We retrospectively compared the outcomes and health-related quality of life (HRQoL) of severe aplastic anemia (SAA) patients who received haploidentical hematopoietic stem cell transplantation with a single unrelated cord blood unit (Haplo-cord HSCT) (n = 180) or matched related donor (MRD)-HSCT (n = 128). After propensity score matching, we were able to match 88 patients in each group and to compare the outcomes between the two matched-pair groups. Haplo-cord recipients exhibited a longer median days for neutrophil engraftment (12 vs 11, P = 0.001) and for platelet engraftment (15 vs 13, P = 0.003). Haplo-cord recipients a high cumulative incidence of grades II–IV acute graft-versus-host disease (GVHD) (29.8 vs 14.0%, P = 0.006), while similar III–IV acute GVHD, total chronic GVHD, and moderate to severe chronic GVHD at four-year (all P < 0.05). Among the Haplo-cord HSCT and MRD-HSCT groups, the four-year GVHD-free/failure-free survival rates were 73.5% and 66.9% (P = 0.388) respectively, and the overall survival rates were 81.5% and 77.2% (P = 0.484), respectively. Similar comparable results also were observed between the corresponding first-line, older or younger than 40 years old subgroups. The Haplo-cord HSCT group exhibited higher scores in the physical component summary, physical functioning, general health and social functioning than the MRD-HSCT group (all P < 0.05). In the multivariate analysis, young age and Haplo-cord HSCT were favorable factors for HRQoL, while moderate to severe cGVHD was associated with lower HRQoL. These results suggest that for SAA patients, Haplo-cord HSCT could achieve at least comparable efficacy and HRQoL to MRD-HSCT.

The similarity of class II HLA genotypes defines patterns of autoreactivity in idiopathic bone marrow failure disorders

Idiopathic aplastic anemia (IAA) is a rare autoimmune bone marrow failure (BMF) disorder initiated by a human leukocyte antigen (HLA)-restricted T-cell response to unknown antigens. As in other autoimmune disorders, the predilection for certain HLA profiles seems to represent an etiologic factor; however, the structure-function patterns involved in the self-presentation in this disease remain unclear. Herein, we analyzed the molecular landscape of HLA complexes of a cohort of 300 IAA patients and almost 3000 healthy and disease controls by deeply dissecting their genotypic configurations, functional divergence, self-antigen binding capabilities, and T-cell receptor (TCR) repertoire specificities. Specifically, analysis of the evolutionary divergence of HLA genotypes (HED) showed that IAA patients carried class II HLA molecules whose antigen-binding sites were characterized by a high level of structural homology, only partially explained by specific risk allele profiles. This pattern implies reduced HLA binding capabilities, confirmed by binding analysis of hematopoietic stem cell (HSC)-derived self-peptides. IAA phenotype was associated with the enrichment in a few amino acids at specific positions within the peptide-binding groove of DRB1 molecules, affecting the interface HLA-antigen-TCR β and potentially constituting the basis of T-cell dysfunction and autoreactivity. When analyzing associations with clinical outcomes, low HED was associated with risk of malignant progression and worse survival, underlying reduced tumor surveillance in clearing potential neoantigens derived from mechanisms of clonal hematopoiesis. Our data shed light on the immunogenetic risk associated with IAA etiology and clonal evolution and on general pathophysiological mechanisms potentially involved in other autoimmune disorders.

Hypoplastic myelodysplastic syndrome and acquired aplastic anemia: Immune‑mediated bone marrow failure syndromes (Review)

Hypoplastic myelodysplastic syndrome (hMDS) and aplastic anemia (AA) are rare hematopoietic disorders characterized by pancytopenia with hypoplastic bone marrow (BM). hMDS and idiopathic AA share overlapping clinicopathological features, making a diagnosis very difficult. The differential diagnosis is mainly based on the presence of dysgranulopoiesis, dysmegakaryocytopoiesis, an increased percentage of blasts, and abnormal karyotype, all favouring the diagnosis of hMDS. An accurate diagnosis has important clinical implications, as the prognosis and treatment can be quite different for these diseases. Patients with hMDS have a greater risk of neoplastic progression, a shorter survival time and a lower response to immunosuppressive therapy compared with patients with AA. There is compelling evidence that these distinct clinical entities share a common pathophysiology based on the damage of hematopoietic stem and progenitor cells (HSPCs) by cytotoxic T cells. Expanded T cells overproduce proinflammatory cytokines (interferon-γ and tumor necrosis factor-α), resulting in decreased proliferation and increased apoptosis of HSPCs. The antigens that trigger this abnormal immune response are not known, but potential candidates have been suggested, including Wilms tumor protein 1 and human leukocyte antigen class I molecules. Our understanding of the molecular pathogenesis of these BM failure syndromes has been improved by next-generation sequencing, which has enabled the identification of a large spectrum of mutations. It has also brought new challenges, such as the interpretation of variants of uncertain significance and clonal hematopoiesis of indeterminate potential. The present review discusses the main clinicopathological differences between hMDS and acquired AA, focuses on the molecular background and highlights the importance of molecular testing.

Infectious Agents and Bone Marrow Failure: A Causal or a Casual Connection?

Acquired bone marrow failure (BMF) syndromes are considered immune-mediated disorders because hematological recovery after immunosuppressive therapies is the strongest indirect evidence of the involvement of immune cells in marrow failure development. Among pathophysiology hypotheses, immune derangement after chronic antigen exposure or cross-reactivity between viral particles and cellular components are the most accepted; however, epitopes against whom these lymphocytes are directed to remain unknown. In this study, we showed that BMF-associated immunodominant clones, namely the most represented T cells carrying an antigen-specific T-cell receptor (TCR) sequence in a random pool, were frequently associated with those described in various infectious diseases, such as cytomegalovirus (CMV) and Mycobacterium tuberculosis infection. We hypothesize that these pathogens might elicit an autoimmune response triggered by cross-reactivity between pathogen-related components and proteins or might be expanded as an unspecific response to a global immune dysregulation during BMF. However, those frequent intracellular pathogens might not only be passengers in marrow failure development, while playing a central role in starting the autoimmune response against hematopoietic stem cells.

A comparative study of porcine antihuman lymphocyte globulin versus antithymocyte globulin-fresenius in an allogeneic hematopoietic cell transplantation conditioning regimen for severe aplastic anemia

OBJECTIVES

To compare the outcomes of antihuman T lymphocyte globulin (ATG-F) and porcine antihuman lymphocyte globulin (p-ALG) as part of a conditioning regimen in hematopoietic stem cell transplantation (HSCT) for severe aplastic anemia (SAA).

METHODS

we performed a retrospective analysis, evaluating the outcome of patients with SAA who received ATG-F based conditioning (n = 26) with those receiving p-ALG conditioning (n = 34).

RESULTS

The median time to neutrophil engraftment was 11 days (range, 8 - 38) and 11 days (range, 9 - 24) in the p-ALG and ATG-F groups (P = 0.857); the median platelet engraftment time was 15 (range, 9 - 330) days and 13 (range, 10 - 56) days (P = 0.155). There were no significant differences in grades II - IV acute graft-versus-host disease (aGVHD), grades III - IV aGVHD, chronic GVHD (cGVHD), and the moderate-severe cGVHD between the ATG-F and p-ALG groups (P>0.05).

DISCUSSION

Patients in the ATG-F group functioned significantly better on role-physical (P = 0.006), general health (P = 0.029), and physical component summary (P = 0.009). The estimated overall survival and failure free survival rates at 5 years were 88.5% ± 6.3% vs. 82.4% ± 6.5% (P = 0.515), 84.6% ± 7.1% vs. 79.4% ± 6.9%, respectively (P = 0.579). The infection rates were 61.53% and 47.05%, respectively (P = 0.265).

CONCLUSION

As part of the conditioning regimen, p-ALG achieved a similar efficacy as ATG-F without increasing the incidence of transplantation complications in SAA patients.

The predictive value of PNH clones, 6p CN-LOH, and clonal TCR gene rearrangement for aplastic anemia diagnosis

Acquired aplastic anemia (AA) is a life-threatening bone marrow aplasia caused by the autoimmune destruction of hematopoietic stem and progenitor cells. There are no existing diagnostic tests that definitively establish AA, and diagnosis is currently made via systematic exclusion of various alternative etiologies, including inherited bone marrow failure syndromes (IBMFSs). The exclusion of IBMFSs, which requires syndrome-specific functional and genetic testing, can substantially delay treatment. AA and IBMFSs can have mimicking clinical presentations, and their distinction has significant implications for treatment and family planning, making accurate and prompt diagnosis imperative to optimal patient outcomes. We hypothesized that AA could be distinguished from IBMFSs using 3 laboratory findings specific to the autoimmune pathogenesis of AA: paroxysmal nocturnal hemoglobinuria (PNH) clones, copy-number-neutral loss of heterozygosity in chromosome arm 6p (6p CN-LOH), and clonal T-cell receptor (TCR) γ gene (TRG) rearrangement. To test our hypothesis, we determined the prevalence of PNH, acquired 6p CN-LOH, and clonal TRG rearrangement in 454 consecutive pediatric and adult patients diagnosed with AA, IBMFSs, and other hematologic diseases. Our results indicated that PNH and acquired 6p CN-LOH clones encompassing HLA genes have ∽100% positive predictive value for AA, and they can facilitate diagnosis in approximately one-half of AA patients. In contrast, clonal TRG rearrangement is not specific for AA. Our analysis demonstrates that PNH and 6p CN-LOH clones effectively distinguish AA from IBMFSs, and both measures should be incorporated early in the diagnostic evaluation of suspected AA using the included Bayesian nomogram to inform clinical application.

Time and residual hematopoiesis are crucial for PNH clones escape in hepatitis-associated aplastic anemia

The presence of paroxysmal nocturnal hemoglobinuria (PNH) clones in aplastic anemia (AA) suggests immunopathogenesis, but when and how PNH clones emerge and proliferate are unclear. Hepatitis-associated aplastic anemia (HAAA) is a special variant of AA, contrarily to idiopathic AA, in HAAA the trigger for immune activation is clearer and represented by the hepatitis and thus serves as a good model for studying PNH clones. Ninety HAAA patients were enrolled, including 61 males and 29 females (median age 21 years). Four hundred three of idiopathic AA have been included as controls. The median time from hepatitis to cytopenia was 50 days (range 0-180 days) and from cytopenia to AA diagnosis was 26 days (range 2-370 days). PNH clones were detected in 8 HAAA patients (8.9%) at diagnosis and in 73 patients with idiopathic AA (IAA) (18.1%). PNH cells accounted for 4.2% (1.09-12.33%) of red cells and/or granulocytes and were more likely to be detected in patients with longer disease history and less severe disease. During follow-up, the cumulative incidence of PNH clones in HAAA increased to 18.9% (17/90). Nine HAAA patients newly developed PNH clones, including six immunosuppressive therapy (IST) nonresponders. The clone size was mostly stable during follow-up, and only 2 of 14 patients showed increased clone size without proof of hemolysis. In conclusion, PNH clones were infrequent in newly diagnosed HAAA, but their frequency increased to one that was similar to the IAA frequency during follow-up. These results suggest that the PNH clone selection/expansion process is dynamic and takes time to establish, confirming that retesting for PNH clones during follow-up is crucial.

Special issues related to the diagnosis and management of acquired aplastic anemia in countries with restricted resources, a report on behalf of the Eastern Mediterranean blood and marrow transplantation (EMBMT) group and severe aplastic anemia working party of the European Society for blood and marrow transplantation (SAAWP of EBMT)

Aplastic anemia is a relatively rare but potentially fatal disorder, with a reported higher incidence in developing countries in comparison to the West. There are significant variations in epidemiological as well as etiological factors of bone marrow failure syndromes in the developing countries in comparison to the developed world. Furthermore, the management of bone marrow failure syndromes in resource constraint settings has significant challenges including delayed diagnosis and referral, limited accessibility to healthcare facilities, treatment modalities as well as limitations related to patients who require allogeneic stem cell transplantation. Here we will provide a review of the available evidence related to specific issues of aplastic anemia in the developing countries and we summarize suggested recommendations from the Eastern Mediterranean blood and bone marrow transplantation (EMBMT) group and the severe aplastic anemia working party of the European Society of blood and marrow transplantation (SAAWP of EBMT) related to the diagnosis and therapeutic options in countries with restricted resources.

Epigenetic Aging and Hematopoietic Cell Transplantation in Patients With Severe Aplastic Anemia

Cellular aging in hematopoietic cell transplantation (HCT) is important in the context of immune reconstitution and age-related complications. Recently, several DNA-methylation (DNAm)-based biomarkers of aging known as "epigenetic clocks" have been introduced as novel tools to predict cellular age. Here, we used Cox proportional hazards models to assess the possible associations of donor pre-HCT DNAm age, and its post-HCT changes, using the recently published lifespan-associated epigenetic clock known as "DNAm-GrimAge," with outcomes among patients with severe aplastic anemia (SAA). The study included 732 SAA patients from the Transplant Outcomes in Aplastic Anemia project, who underwent unrelated donor HCT and for whom a donor pre-HCT blood DNA sample was available; 41 also had a post-HCT sample collected at day 100. In multivariable analyses, we found similar associations for donor chronological age and pre-HCT DNAm-GrimAge with post-HCT survival (hazard ratio [HR] per decade = 1.13; 95% confidence interval [CI], 0.99-1.28; P = .07 and HR = 1.14; 95% CI, 0.99-1.28; P = .06, respectively). In donors with 10+ years of GrimAge acceleration (ie, deviation from expected DNAm age for chronological age), elevated risks of chronic graft versus host disease (HR = 2.4; 95% CI, 1.21-4.65; P = .01) and possibly post-HCT mortality (HR = 1.79; 95% CI, 0.96-3.33; P = .07) were observed. In the subset with post-HCT samples, we observed a significant increase in DNAm-GrimAge in the first 100 days after HCT (median change 12.5 years, range 1.4 to 26.4). Higher DNAm-GrimAge after HCT was associated with inferior survival (HR per year = 1.11; 95% CI, 1.02-1.21; P = .01), predominantly within the first year after HCT. This study highlights the possible role cellular aging may play in HCT outcomes.

Advances in Aptamer-Based Biomarker Discovery

The discovery and identification of biomarkers promote the rational and fast development of medical diagnosis and therapeutics. Clinically, the application of ideal biomarkers still is limited due to the suboptimal technology in biomarker discovery. Aptamers are single-stranded deoxyribonucleic acid or ribonucleic acid molecules and can selectively bind to varied targets with high affinity and specificity. Compared with antibody, aptamers have desirable advantages, such as flexible design, easy synthesis and convenient modification with different functional groups. Currently, different aptamer-based technologies have been developed to facilitate biomarker discovery, especially CELL-SELEX and SOMAScan technology. CELL-SELEX technology is mainly used to identify cell membrane surface biomarkers of various cells. SOMAScan technology is an unbiased biomarker detection method that can analyze numerous and even thousands of proteins in complex biological samples at the same time. It has now become a large-scale multi-protein biomarker discovery platform. In this review, we introduce the aptamer-based biomarker discovery technologies, and summarize and highlight the discovered emerging biomarkers recently in several diseases.

When Should We Think of Myelodysplasia or Bone Marrow Failure in a Thrombocytopenic Patient? A Practical Approach to Diagnosis

Thrombocytopenia can arise from various conditions, including myelodysplastic syndromes (MDS) and bone marrow failure (BMF) syndromes. Meticulous assessment of the peripheral blood smear, identification of accompanying clinical conditions, and characterization of the clinical course are important for initial assessment of unexplained thrombocytopenia. Increased awareness is required to identify patients with suspected MDS or BMF, who are in need of further investigations by a step-wise approach. Bone marrow cytomorphology, histopathology, and cytogenetics are complemented by myeloid next-generation sequencing (NGS) panels. Such panels are helpful to distinguish reactive cytopenia from clonal conditions. MDS are caused by mutations in the hematopoietic stem/progenitor cells, characterized by cytopenia and dysplasia, and an inherent risk of leukemic progression. Aplastic anemia (AA), the most frequent acquired BMF, is immunologically driven and characterized by an empty bone marrow. Diagnosis remains challenging due to overlaps with other hematological disorders. Congenital BMF, certainly rare in adulthood, can present atypically with thrombocytopenia and can be misdiagnosed. Analyses for chromosome fragility, telomere length, and germline gene sequencing are needed. Interdisciplinary expert teams contribute to diagnosis, prognostication, and choice of therapy for patients with suspected MDS and BMF. With this review we aim to increase the awareness and provide practical approaches for diagnosis of these conditions in suspicious cases presenting with thrombocytopenia.

Thrombopoietin Promotes Cell Proliferation and Attenuates Apoptosis of Aplastic Anemia Serum-Treated 32D Cells via Activating STAT3/STAT5 Signaling Pathway and Modulating Apoptosis-Related Mediators

The present study aimed to investigate the effect and possible mechanism of recombinant human thrombopoietin (rhTPO) on mouse 32D cells (a mouse myeloid progenitor cell line) treated with serum from patients with aplastic anemia and to elucidate the potential mechanism of rhTPO in the treatment of aplastic anemia. After treatment with aplastic anemia serum, the apoptotic rate of 32D cells was increased and the proliferation of 32D cells was significantly inhibited. rhTPO reduced the apoptotic rate and promoted the proliferation of 32D cells, while rhTPO failed to restore the cell proliferation of 32D cells from aplastic anemia serum group to the normal level as compared to that from the normal serum group. The phosphorylation level of STAT3 protein was higher, and the phosphorylation level of STAT5 protein was lower in 32D cells from aplastic anemia serum group than that in normal serum group. After rhTPO treatment, the phosphorylation level of STAT3 protein in aplastic anemia serum group was decreased and the phosphorylation level of STAT5 protein was increased. The expression levels of Survivin and Bcl-2 were significantly decreased in 32D cells from aplastic anemia serum group, which were significantly increased after rhTPO treatment. The expression level of Bax protein in 32D cells from the normal serum group after rhTPO treatment was significantly decreased; while the mRNA expression level of Bax was not affected by rhTPO. The expression levels of Bax mRNA and protein were significantly up-regulated in 32D cells from aplastic anemia serum group, which was significantly decreased by rhTPO treatment. In conclusion, our results indicated that aplastic anemia serum impaired proliferative potential and enhanced apoptosis of 32D cells. Further mechanistic studies revealed that rhTPO promoted cell proliferation and attenuated apoptosis of aplastic anemia serum-treated 32D cells via activating STAT3/STAT5 signaling pathway and modulating apoptosis-related mediators.

Hypermethylation-mediated downregulation of long non-coding RNA MEG3 inhibits osteogenic differentiation of bone marrow mesenchymal stem cells and promotes pediatric aplastic anemia

BACKGROUND

The reduced osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) is the typical characteristics of pediatric aplastic anemia (AA) pathogenesis. Long non-coding RNA MEG3 is reported to promote osteogenic differentiation of BMSCs via inducing BMP4 expression.

OBJECTIVE

This study aims to investigate the mechanism of DNMT1/MEG3/BMP4 pathway in osteogenic differentiation of BMSCs in pediatric AA.

METHODS

BMSCs were isolated and purified from bone marrows of pediatric AA patients (n = 5) and non-AA patients (n = 5). The expression of DNMT1, MEG3, and BMP4 in isolated BMSCs was detected using quantitative real-time PCR and western blot analysis. Osteogenic differentiation was determined using Alizarin red staining. The methylation of MEG3 promoter and the interaction between DNMT1 and MEG3 promoter were detected using methylation-specific PCR and chromatin immunoprecipitation assay, respectively.

RESULTS

Lowly expressed MEG3 and BMP4 and highly expressed DNMT1 were observed in BMSCs of pediatric AA patients. The overexpression of MEG3 promoted osteogenic differentiation of BMSCs. Luciferase reporter assay showed that MEG3 overexpression increased transcriptional activity of BMP4. The inhibitor of methylation, 5-azacytidine, suppressed DNMT1 expression and reduced methylation of MEG3 promoter. Overexpression of DNMT1 increased the binding between DNMT1 and MEG3 promoter. The simultaneous overexpression of DNMT1 and MEG3 restored the inhibition of osteogenic differentiation caused by DNMT1 overexpression alone.

CONCLUSIONS

Our findings indicated that DNMT1 mediated the hypermethylation of MEG3 promoter in BMSCs, and DNMT1/MEG3/BMP4 pathway modulated osteogenic differentiation of BMSCs in pediatric AA.

Bone Marrow Failure Syndromes, Overlapping Diseases with a Common Cytokine Signature

Bone marrow failure (BMF) syndromes are a heterogenous group of non-malignant hematologic diseases characterized by single- or multi-lineage cytopenia(s) with either inherited or acquired pathogenesis. Aberrant T or B cells or innate immune responses are variously involved in the pathophysiology of BMF, and hematological improvement after standard immunosuppressive or anti-complement therapies is the main indirect evidence of the central role of the immune system in BMF development. As part of this immune derangement, pro-inflammatory cytokines play an important role in shaping the immune responses and in sustaining inflammation during marrow failure. In this review, we summarize current knowledge of cytokine signatures in BMF syndromes.

The Role of mTOR Inhibitors in Hematologic Disease: From Bench to Bedside

The mTOR pathway plays a central role in many cellular processes, such as cellular growth, protein synthesis, glucose, and lipid metabolism. Aberrant regulation of mTOR is a hallmark of many cancers, including hematological malignancies. mTOR inhibitors, such as Rapamycin and Rapamycin analogs (Rapalogs), have become a promising class of agents to treat malignant blood diseases-either alone or in combination with other treatment regimens. This review highlights experimental evidence underlying the molecular mechanisms of mTOR inhibitors and summarizes their evolving role in the treatment of hematologic disease, including leukemia, lymphoma, myeloma, immune hemocytopenia, and graft-versus-host disease (GVHD). Based on data presented in this review, we believe that mTOR inhibitors are becoming a trusted therapeutic in the clinical hematologist's toolbelt and should be considered more routinely in combination therapy for the management of hematologic disease.

A Review of Infections After Hematopoietic Cell Transplantation Requiring PICU Care: Transplant Timeline Is Key

Despite major advances in antimicrobial prophylaxis and therapy, opportunistic infections remain a major cause of morbidity and mortality after pediatric hematopoietic cell transplant (HCT). Risk factors associated with the development of opportunistic infections include the patient's underlying disease, previous infection history, co-morbidities, source of the donor graft, preparative therapy prior to the graft infusion, immunosuppressive agents, early and late toxicities after transplant, and graft-vs.-host disease (GVHD). Additionally, the risk for and type of infection changes throughout the HCT course and is greatly influenced by the degree and duration of immunosuppression of the HCT recipient. Hematopoietic cell transplant recipients are at high risk for rapid clinical decompensation from infections. The pediatric intensivist must remain abreast of the status of the timeline from HCT to understand the risk for different infections. This review will serve to highlight the infection risks over the year-long course of the HCT process and to provide key clinical considerations for the pediatric intensivist by presenting a series of hypothetical HCT cases.

The Effectiveness of Rapamycin Combined with Eltrombopag in Murine Models of Immune-Mediated Bone Marrow Failure

Severe aplastic anemia (SAA) is a rare disease characterized by severe pancytopenia and bone marrow failure. Most patients with AA respond to immunosuppressive therapy (IST), usually as antithymocyte globulin (ATG) and cyclosporine (CsA), but some relapse on CsA withdrawal or require long-term administration of CsA to maintain blood counts. Recent research has found that rapamycin (Rapa) was an effective therapy in mouse models of immune-mediated bone marrow failure. However, it has not achieved a satisfactory effect in clinical application. At present, many studies have confirmed that eltrombopag (ELT) combined with IST can improve the curative effect of AA patients. Then, whether Rapa combined Elt in the treatment of AA will acquire better efficacy than a single drug application remains unclear. In this study, an immune attack-mediated AA mouse model was constructed by total body irradiation (TBI) and allo-lymphocyte infusion. In our study, we tested the efficacy of Rapa combined with Elt as a new treatment in mouse models of immune-mediated bone marrow failure. It showed that treatment with Rapa in combination Elt in the AA mouse model ameliorated pancytopenia and extended animal survival in a manner comparable to the standard dose of CsA and Rapa alone. However, there was no significant improvement effect on the number and function of NK cells and their subsets, mDCs, and CD4+/CD8+ ratio in AA mice after the therapy of Rapa combined with Elt compared with Rapa alone. Furthermore, the secretion of IL-10 of Tregs in AA mice increased significantly after the therapy of Rapa combined with Elt, but there was no significant difference in the number of Treg cells. We did not observe the difference in the curative effect of the Rapa group and CsA group, but for IL-10/Tregs ratio, the Rapa group was superior to the CsA group. And the IFN-r secretion of CD8+T cells in AA mice decreased significantly after the combination therapy of Rapa and Elt than Rapa alone. Compared with the AA group, the level of plasma IFN-γ, IL-2, and TNF-α decreased significantly (P < 0.05), but IL-10, IL-4, IL-5, and IL-1β increased significantly in the Rapa group (P < 0.05). As for IL-10, IL-12p70, IL-2, IL-6, KC/GRO, and TNF-α, the therapy of Rapa combined with Elt showed a more significant effect than Rapa alone in AA mice. To some extent, this study had shown a relatively better synergistic effect in murine models of immune-mediated bone marrow failure after the combination therapy of Rapa and Elt, which was a promising clinical utility in SAA treatment.

Epidemiology of aplastic anemia: a study of 1324 cases

Objective: Prevalence of aplastic anemia (AA) is high in the Asian population. This study was done to explore the etiology and association of AA with various socio-economic and environmental factors.Study design and setting: Study included 1324 consecutive AA cases registered at Armed Forces Bone Marrow Transplant Centre Rawalpindi, Pakistan, from March 2001 to August 2016. The study questionnaire was completed through an interview. It included patients' socio-demographic details, personal and family medical history, environmental attributes and clinico-hematological features.Results: The median age of patients was 20 years, 997 were male and 327 female. Distribution of non-severe, severe and very severe AA was 230 (17.4%); 598 (45.2%) and 496 (37.4%), respectively. The majority of patients were from low (n = 761, 57.5%) or middle socioeconomic class (n = 543, 41%). Consanguinity among patients (n = 806, 61%) was slightly higher than the national statistics. History of chemical exposures included fertilizers (n = 116, 8.7%), pesticides (n = 56, 4.2%) and industrial chemicals (n = 37, 2.8%). PNH clone was found in 63 of AA patients. After excluding 298 patients undergoing HSCT and 660 deaths/lost to follow-up, disease evolution was observed in 38(10.4%) patients out of 366 evaluable patients. These included PNH = 18, MDS = 11 and AML = 9.Discussion: Due to lack of funding and adequate human resource at the center, age and sex-matched controls could not be included. Other limitations were a lack of molecular testing to exclude the possibility of inherited bone marrow failure syndromes on a genetic basis.Conclusion: Younger age, male predominance and higher consanguinity point toward genetic factors in AA etiology among the South Asian population.

CTLA-4 and HLA-DQ are key molecules in the regulation of mDC-mediated cellular immunity by Tregs in severe aplastic anemia

Background

Regulatory T cells (Tregs) inhibit the activation of cluster of differentiation (CD) 4⁺, CD8⁺T cells and the antigen‐presenting process of antigen‐presenting cells, and may play an important role in acquired severe aplastic anemia (SAA).

Methods

Flow cytometry was used to measure CD4⁺CD25⁺CD127^dim Tregs, cytotoxic T lymphocyte antigen 4 (CTLA‐4) expression on Tregs, and human leukocyte antigen (HLA)‐DQ expression on myeloid dendritic cells (mDCs). The correlations of CTLA‐4 and HLA‐DQ with immune status and clinical indicators and the changes in these indicators after immunosuppressive therapy (IST) were analyzed.

Results

In SAA patients, the number of Tregs and their CTLA‐4 expression were low but recovered after IST; the HLA‐DQ expression on mDCs was high but decreased after IST. The CTLA‐4 expression on Tregs and the HLA‐DQ expression on mDCs showed a negative correlation. The CTLA‐4 on Tregs was positively but HLA‐DQ on mDCs negatively correlated with the number of Tregs, natural killer (NK) cell number, and CD4⁺T/CD8⁺T ratio. CTLA‐4 was positively but HLA‐DQ negatively correlated with the percentage of granulocytoid and erythroid cells in bone marrow, white blood cell count in PB, absolute neutrophil count in PB, and the percentage of reticulocytes in PB.

Conclusions

CTLA‐4/HLA‐DQ may be key in the regulation of Tregs on mDCs in SAA patients. Our findings should be helpful for further investigation of the mechanism of immune pathogenesis in SAA patients. Studies on the regulators of Treg and CTLA‐4 activity will be valuable for SAA therapeutic target research and disease monitoring.

Aptamers and Antisense Oligonucleotides for Diagnosis and Treatment of Hematological Diseases

Aptamers or chemical antibodies are single-stranded DNA or RNA oligonucleotides that bind proteins and small molecules with high affinity and specificity by recognizing tertiary or quaternary structures as antibodies. Aptamers can be easily produced in vitro through a process known as systemic evolution of ligands by exponential enrichment (SELEX) or a cell-based SELEX procedure. Aptamers and modified aptamers, such as slow, off-rate, modified aptamers (SOMAmers), can bind to target molecules with less polar and more hydrophobic interactions showing slower dissociation rates, higher stability, and resistance to nuclease degradation. Aptamers and SOMAmers are largely employed for multiplex high-throughput proteomics analysis with high reproducibility and reliability, for tumor cell detection by flow cytometry or microscopy for research and clinical purposes. In addition, aptamers are increasingly used for novel drug delivery systems specifically targeting tumor cells, and as new anticancer molecules. In this review, we summarize current preclinical and clinical applications of aptamers in malignant and non-malignant hematological diseases.