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

Research and analysis of differential gene expression in CD34 hematopoietic stem cells in myelodysplastic syndromes

OBJECTIVE

This study aims to investigate and analyze the differentially expressed genes (DEGs) in CD34 + hematopoietic stem cells (HSCs) from patients with myelodysplastic syndromes (MDS) through bioinformatics analysis, with the ultimate goal of uncovering the potential molecular mechanisms underlying pathogenesis of MDS. The findings of this study are expected to provide novel insights into clinical treatment strategies for MDS.

METHODS

Initially, we downloaded three datasets, GSE81173, GSE4619, and GSE58831, from the public Gene Expression Omnibus (GEO) database as our training sets, and selected the GSE19429 dataset as the validation set. To ensure data consistency and comparability, we standardized the training sets and removed batch effects using the ComBat algorithm, thereby integrating them into a unified gene expression dataset. Subsequently, we conducted differential expression analysis to identify genes with significant changes in expression levels across different disease states. In order to enhance prediction accuracy, we incorporated six common predictive models and trained them based on the filtered differential gene expression dataset. After comprehensive evaluation, we ultimately selected three algorithms-Lasso regression, random forest, and support vector machine (SVM)-as our core predictive models. To more precisely pinpoint genes closely related to disease characteristics, we utilized the aforementioned three machine learning methods for prediction and took the intersection of these prediction results, yielding a more robust list of genes associated with disease features. Following this, we conducted in-depth analysis of these key genes in the training set and validated the results independently using the GSE19429 dataset. Furthermore, we performed differential analysis of gene groups, co-expression analysis, and enrichment analysis to delve deeper into the mechanisms underlying the roles of these genes in disease initiation and progression. Through these analyses, we aim to provide new insights and foundations for disease diagnosis and treatment. Figure illustrates the data preprocessing and analysis workflow of this study.

RESULTS

Our analysis of differentially expressed genes (DEGs) in CD34+ hematopoietic stem cells (HSCs) from patients with myelodysplastic syndromes (MDS) revealed significant differences in gene expression patterns compared to the control group (individuals without MDS). Specifically, the expression levels of two key genes, IRF4 and ELANE, were notably downregulated in CD34+ HSCs of MDS patients, indicating their downregulatory roles in the pathological process of MDS.

CONCLUSION

This study sheds light on the potential molecular mechanisms underlying MDS, with a particular focus on the pivotal roles of IRF4 and ELANE as key pathogenic genes. Our findings provide a novel perspective for understanding the complexity of MDS and exploring therapeutic strategies. They may also guide the development of precise and effective treatments, such as targeted interventions directed against these genes.

Acute effects of TLR3 agonist Poly(I:C) on bone marrow hematopoietic progenitor cells in mice

Hematopoietic progenitor cells (HPCs) in bone marrow with limited abilities for self-renewal and differentiation continuously supply hematopoietic cells through life. When suffering infection or inflammation, HPCs will actively proliferate to provide differentiated hematopoietic cells to maintain hematopoietic homeostasis. Poly(I:C), an agonist of TLR3, can specifically activate Type I interferon (IFN-I) signaling which exerts anti-inflammatory effects and influence hematopoiesis after infection. However, the effects of Poly(I:C)-induced IFN-I on the bone marrow hematopoietic system still deserve attention. In this study, our results revealed the efficacy of the IFN-I model, with a remarkably decrease in HPCs and a sharp elevation in LSKs numbers after single dose of Poly(I:C) injection. Apoptotic ratios of HPCs and LSKs significantly increased 48 h after Poly(I:C) treatment. Application of Poly(I:C) prompted the transition of HPCs and LSKs from G0 to G1 phases, potentially leading to the accelerated exhaustion of HPCs. From the cobblestone area-forming cell (CAFC) assay, we speculate that Poly(I:C) impairs the differentiation capacity of HPCs as well as their colony-forming ability. RT-qPCR and immunohistochemistry revealed significant upregulation of IFN-I associated genes and proteins following Poly(I:C) treatment. In conclusion, a single dose of Poly(I:C) induced an acute detrimental effect on HPCs within 48 h potentially due to TLR3 engagement. This activation cascaded into a robust IFN-I response emanating from the bone marrow, underscoring the intricate immunological dynamics at play following Poly(I:C) intervention.

Annexin A1: a key regulator of T cell function and bone marrow adiposity in aplastic anaemia

This study investigates the role of Annexin A1 (ANXA1) in regulating T cell function and its implications in bone marrow adiposity in aplastic anaemia (AA). Utilizing single-cell sequencing analysis, we compared bone marrow tissues from AA patients and healthy individuals, focusing on T cell subgroups and their impact on bone marrow pathology. Our findings reveal a significant activation of CD8+ T cells in AA, driven by reduced ANXA1 expression. This heightened T cell activity promotes adipogenesis in bone marrow-derived mesenchymal stem cells via IFN-γ secretion. Overexpression of ANXA1 was found to suppress this process, suggesting its therapeutic potential in AA treatment. The study highlights ANXA1 as a crucial regulator in the AA-associated immune microenvironment and bone marrow adiposity. KEY POINTS: This study found that ANXA1 is significantly downregulated in AA and provides detailed insights into its critical role in the disease. The study demonstrates the excessive activation of CD8+ T cells in the progression of AA. The research shows that the overexpression of ANXA1 can effectively inhibit the activation of CD8+ T cells. The study confirms that overexpression of ANXA1 reduces the secretion of the cytokine IFN-γ, decreases adipogenesis in bone marrow-derived mesenchymal stem cells and may improve AA symptoms. This research provides new molecular targets for the treatment of AA.

Dysregulated T-cell homeostasis and decreased CD30+ Treg proliferating in aplastic anemia

Aplastic anemia (AA) is an autoimmune hematopoietic disease mediated by autoreactive T cells leading to bone marrow failure. However, the precise role of autoreactive T cells in the development of AA is not fully understood, hindering the advancement of therapeutic and diagnostic strategies. In this study, we conducted a single-cell transcriptome analysis of CD8+ T cells, conventional CD4+ T (CD4+ Tconv) cells, and Treg cells, to elucidate the potential disruption of T cell homeostasis in patients with AA. We identified changes in CD4+ Tconv cells, including loss of homeostasis in naïve and memory cells and increased differentiation potential in T helper type 1 (TH1), T helper type 2 (TH2), and T helper type 17 (TH17) cells. Additionally, we identified naïve and memory CD8+ T cells that were enforced into an effector state. CD127 is an ideal surface marker for assessing the immune state of CD8+ T cells，as identified by flow cytometry. Abnormal expression of TNFSF8 has been observed in AA and other autoimmune diseases. Flow cytometry analysis revealed that TNFRSF8 (CD30), a receptor for TNFSF8, was predominantly present in human Treg cells. Importantly, patients with AA have a decreased CD30+ Treg subset. RNA-sequencing analysis revealed, that the CD30+ Treg cells are characterized by high proliferation and a remarkable immunosuppressive phenotype. Taken, together, we propose that abnormal TNFSF8/TNFRSF8 signaling is involved in dysfunctional T cell immunity by increasing the destruction of CD30+ Treg cells.

When inflammatory stressors dramatically change, disease phenotypes may transform between autoimmune hematopoietic failure and myeloid neoplasms

Aplastic anemia (AA) and hypoplastic myelodysplastic syndrome are paradigms of autoimmune hematopoietic failure (AHF). Myelodysplastic syndrome and acute myeloid leukemia are unequivocal myeloid neoplasms (MNs). Currently, AA is also known to be a clonal hematological disease. Genetic aberrations typically observed in MNs are detected in approximately one-third of AA patients. In AA patients harboring MN-related genetic aberrations, a poor response to immunosuppressive therapy (IST) and an increased risk of transformation to MNs occurring either naturally or after IST are predicted. Approximately 10%-15% of patients with severe AA transform the disease phenotype to MNs following IST, and in some patients, leukemic transformation emerges during or shortly after IST. Phenotypic transformations between AHF and MNs can occur reciprocally. A fraction of advanced MN patients experience an aplastic crisis during which leukemic blasts are repressed. The switch that shapes the disease phenotype is a change in the strength of extramedullary inflammation. Both AHF and MNs have an immune-active bone marrow (BM) environment (BME). In AHF patients, an inflamed BME can be evoked by infiltrated immune cells targeting neoplastic molecules, which contributes to the BM-specific autoimmune impairment. Autoimmune responses in AHF may represent an antileukemic mechanism, and inflammatory stressors strengthen antileukemic immunity, at least in a significant proportion of patients who have MN-related genetic aberrations. During active inflammatory episodes, normal and leukemic hematopoieses are suppressed, which leads to the occurrence of aplastic cytopenia and leukemic cell regression. The successful treatment of underlying infections mitigates inflammatory stress-related antileukemic activities and promotes the penetration of leukemic hematopoiesis. The effect of IST is similar to that of treating underlying infections. Investigating inflammatory stress-powered antileukemic immunity is highly important in theoretical studies and clinical practice, especially given the wide application of immune-activating agents and immune checkpoint inhibitors in the treatment of hematological neoplasms.

Fifth Edition of the World Health Classification of Tumors of the Hematopoietic and Lymphoid Tissue: Myeloid Neoplasms

In this manuscript, we review myeloid neoplasms in the fifth edition of the World Health Organization classification of hematolymphoid tumors (WHO-HEM5), focusing on changes from the revised fourth edition (WHO-HEM4R). Disease types and subtypes have expanded compared with WHO-HEM4R, mainly because of the expansion in genomic knowledge of these diseases. The revised classification is based on a multidisciplinary approach including input from a large body of pathologists, clinicians, and geneticists. The revised classification follows a hierarchical structure allowing usage of family (class)-level definitions where the defining diagnostic criteria are partially met or a complete investigational workup has not been possible. Overall, the WHO-HEM5 revisions to the classification of myeloid neoplasms include major updates and revisions with increased emphasis on genetic and molecular drivers of disease. The most notable changes have been applied to the sections of acute myeloid leukemia and myelodysplastic neoplasms (previously referred to as myelodysplastic syndrome) with incorporation of novel, disease-defining genetic changes. In this review we focus on highlighting the updates in the classification of myeloid neoplasms, providing a comparison with WHO-HEM4R, and offering guidance on how the new classification can be applied to the diagnosis of myeloid neoplasms in routine practice.

Leukemic transformation during anti-tuberculosis treatment in aplastic anemia-paroxysmal nocturnal hemoglobinuria syndrome: A case report and review of literature

BACKGROUND

Accumulating evidence demonstrates that autoimmune hematopoietic failure and myeloid neoplasms have an intrinsic relationship with regard to clonal hematopoiesis and disease evolution. In approximately 10%-15% of patients with severe aplastic anemia (SAA), the disease phenotype is transformed into myeloid neoplasms following antithymocyte globulin plus cyclosporine-based immunosuppressive therapy. In some of these patients, myeloid neoplasms appear during or shortly after immunosuppressive therapy. Leukemic transformation in SAA patients during anti-tuberculosis treatment has not been reported.

CASE SUMMARY

A middle-aged Chinese female had a 6-year history of non-SAA and a 2-year history of paroxysmal nocturnal hemoglobinuria (PNH). With aggravation of systemic inflammatory symptoms, severe pancytopenia developed, and her hemoglobinuria disappeared. Laboratory findings in cytological, immunological and cytogenetic analyses of bone marrow samples met the diagnostic criteria for "SAA." Definitive diagnosis of disseminated tuberculosis was made in the search for infectious niches. Remarkable improvement in hematological parameters was achieved within 1 mo of anti-tuberculosis treatment, and complete hematological remission was achieved within 4 mo of treatment. Frustratingly, the hematological response lasted for only 3 mo, and pancytopenia reemerged. At this time, cytological findings (increased bone marrow cellularity and an increased percentage of myeloblasts that accounted for 16.0% of all nucleated hematopoietic cells), immunological findings (increased percentage of cluster of differentiation 34+ cells that accounted for 12.28% of all nucleated hematopoietic cells) and molecular biological findings (identification of somatic mutations in nucleophosmin-1 and casitas B-lineage lymphoma genes) revealed that "SAA" had transformed into acute myeloid leukemia with mutated nucleophosmin-1. The transformation process suggested that the leukemic clones were preexistent but were suppressed in the PNH and SAA stages, as development of symptomatic myeloid neoplasm through acquisition and accumulation of novel oncogenic mutations is unlikely in an interval of only 7 mo. Aggravation of inflammatory stressors due to disseminated tuberculosis likely contributed to the repression of normal and leukemic hematopoiesis, and the relief of inflammatory stressors due to anti-tuberculosis treatment contributed to penetration of neoplastic hematopoiesis. The concealed leukemic clones in the SAA and PNH stages raise the possibility of an inflammatory stress-fueled antileukemic mechanism.

CONCLUSION

Aggravated inflammatory stressors can repress normal and leukemic hematopoiesis, and relieved inflammatory stressors can facilitate penetration of neoplastic hematopoiesis.

Use of steroids in the management of low-risk myelodysplastic syndromes with autoimmune features

BACKGROUND

The boundaries between myelodysplastic syndromes (MDS) and immune-mediated cytopenias are often difficult to establish and both conditions may benefit from immunosuppressive therapy. The optimal timing and doses of immunosuppressants are largely unknown.

MATERIALS AND METHODS

We systematically evaluated a retrospective cohort of 79 patients with low-risk MDS tested for anti-erythrocyte or anti-platelet autoantibodies to assess their frequency and the efficacy of immunosuppression, particularly with steroids.

RESULTS

We found autoantibody positivity in 43% of cases and overt autoimmune diseases in 18%, including autoimmune hemolytic anemia, immune thromboctyopenia, and Evans syndrome. Steroid treatment improved cytopenia in about half of patients, with 26% achieving a complete recovery lasting for a median of 12 months. Better responses were observed in anemic patients with anti-erythrocyte autoantibodies than in those with anti-platelet autoantibodies, and the combination with recombinant erythropoietin (7/10) had a possible synergistic effect. Steroid doses were heterogeneous depending on the clinical intent (i.e., anti-inflammatory, immunosuppressive, anabolizing). Patients treated with a dose of 1 mg/kg day of prednisone for overt autoimmune cytopenia showed high rates of complete responses (60%).

DISCUSSION

This observation suggests a trial with a short course (2-3 weeks) of standard steroid doses to ascertain efficacy and properly silence the autoimmune pathogenic mechanism. Steroid-related adverse events (16% of cases) should be monitored carefully in this elderly, frail population. In conclusion, features of autoimmunity are present in more than two-thirds of low-risk MDS patients and a trial with prednisone 0.5-1 mg/kg day for 2-3 weeks, with proper monitoring of adverse events, may be useful to improve cytopenias in selected cases.

Tuberculosis-induced aplastic crisis and atypical lymphocyte expansion in advanced myelodysplastic syndrome: A case report and review of literature

BACKGROUND

Myelodysplastic syndrome (MDS) is caused by malignant proliferation and ineffective hematopoiesis. Oncogenic somatic mutations and increased apoptosis, necroptosis and pyroptosis lead to the accumulation of earlier hematopoietic progenitors and impaired productivity of mature blood cells. An increased percentage of myeloblasts and the presence of unfavorable somatic mutations are signs of leukemic hematopoiesis and indicators of entrance into an advanced stage. Bone marrow cellularity and myeloblasts usually increase with disease progression. However, aplastic crisis occasionally occurs in advanced MDS.

CASE SUMMARY

A 72-year-old male patient was definitively diagnosed with MDS with excess blasts-1 (MDS-EB-1) based on an increase in the percentages of myeloblasts and cluster of differentiation (CD)34+ hematopoietic progenitors and the identification of myeloid neoplasm-associated somatic mutations in bone marrow samples. The patient was treated with hypomethylation therapy and was able to maintain a steady disease state for 2 years. In the treatment process, the advanced MDS patient experienced an episode of progressive pancytopenia and bone marrow aplasia. During the aplastic crisis, the bone marrow was infiltrated with sparsely distributed atypical lymphocytes. Surprisingly, the leukemic cells disappeared. Immunological analysis revealed that the atypical lymphocytes expressed a high frequency of CD3, CD5, CD8, CD16, CD56 and CD57, suggesting the activation of autoimmune cytotoxic T-lymphocytes and natural killer (NK)/NKT cells that suppressed both normal and leukemic hematopoiesis. Elevated serum levels of inflammatory cytokines, including interleukin (IL)-6, interferon-gamma (IFN-γ) and tumor necrosis factor-alpha (TNF-α), confirmed the deranged type I immune responses. This morphological and immunological signature led to the diagnosis of severe aplastic anemia secondary to large granule lymphocyte leukemia. Disseminated tuberculosis was suspected upon radiological examinations in the search for an inflammatory niche. Antituberculosis treatment led to reversion of the aplastic crisis, disappearance of the atypical lymphocytes, increased marrow cellularity and 2 mo of hematological remission, providing strong evidence that disseminated tuberculosis was responsible for the development of the aplastic crisis, the regression of leukemic cells and the activation of CD56+ atypical lymphocytes. Reinstitution of hypomethylation therapy in the following 19 mo allowed the patient to maintain a steady disease state. However, the patient transformed the disease phenotype into acute myeloid leukemia and eventually died of disease progression and an overwhelming infectious episode.

CONCLUSION

Disseminated tuberculosis can induce CD56+ lymphocyte infiltration in the bone marrow and in turn suppress both normal and leukemic hematopoiesis, resulting in the development of aplastic crisis and leukemic cell regression.

Flared inflammatory episode transforms advanced myelodysplastic syndrome into aplastic pancytopenia: A case report and literature review

BACKGROUND

Myelodysplastic syndrome (MDS) is a hematological neoplasm, and an increase in myeloblasts is representative of leukemic hematopoiesis in advanced MDS. Low-risk MDS usually exhibits deranged autoimmunity resembling that of aplastic anemia (AA), whereas advanced MDS is characterized by a phenotype of immune exhaustion. MDS can be normo/hyperplastic or hypoplastic. Generally, bone marrow cellularity and myeloblasts increase with disease progression. Transformation from advanced MDS to AA-like syndrome with leukemic cell regression has not previously been reported.

CASE SUMMARY

A middle-aged Chinese woman had a 4-year history of leukocytopenia. Six months prior to admission, the patient developed gradually worsening fatigue and performance status. The leukocytopenia further progressed. She was diagnosed with MDS with excess blasts-2 based on increased bone marrow cellularity and an increased percentage of myeloblasts on marrow and blood smears, an increased percentage of cluster of differentiation (CD)34+CD33+ progenitors in immunotyping analysis, a normal karyotype in cytogenetic analysis, and the identification of somatic mutations in CBL, KMT2D and NF1 in molecular analysis. Initially, neutropenia was the predominant hematological abnormality, with mild anemia and thrombocytosis, and the degree of fatigue was far more severe than the degree of anemia. In the following months, the patient experienced several febrile episodes. Intravenous antibiotic treatments were able to control the febrile episodes, but the elevated inflammatory indices persisted. The hematological parameters dramatically fluctuated with the waxing and waning of the inflammatory episodes. With recurrent flares of the inflammatory condition, agranulocytosis and severe anemia developed, with mild thrombocytopenia. During the patient’s hospitalization, computed tomography (CT) scans revealed the presence of extensive inflammatory lesions involving the lungs, mediastinum, pleura, gastrointestinal tract, peritoneum and urinary tract, with imaging features suggestive of the reactivation of disseminated tuberculosis. Reevaluation of the bone marrow smears revealed that the cellularity became hypoplastic, and the leukemic cells regressed, suggesting that both normal and leukemic hematopoiesis had been heavily suppressed. Immunological analysis of the bone marrow samples revealed a decreased percentage of CD34+ cells and an immunological signature resembling that of severe AA (SAA), confirming the regression of the leukemic cells by autoimmune-mediated attacks. The patient demonstrated resistance to multiple drugs, including antituberculotics, recombinant human granulocyte colony-stimulating factor, broad-spectrum antibiotics, voriconazole, ganciclovir, immune suppressants, eltrombopag and intravenous immunoglobulin, which further worsened the hematological injury and patient’s performance status. The patient eventually died of overwhelming infection and multidrug resistance.

CONCLUSION

Advanced MDS can transform to aplastic cytopenia with leukemic cell regression and an immunological signature of SAA during inflammatory flare-ups.

Hypoplastic Myelodysplastic Syndrome: Symptom of Methotrexate Toxicity in Rheumatoid Arthritis

Methotrexate is the conventional disease-modifying anti-rheumatic drug (DMARD) which is considered the drug of choice in the treatment of rheumatoid arthritis, but its prolonged use without monitoring leads to a number of complications involving different body systems. The toxic effects of long-term methotrexate (MTX) therapy mainly involve the liver, skin, gastrointestinal tract (GIT) and bone marrow. In the bone marrow, it mainly causes suppression of normal functionality, leading to the formation of abnormal blast cells and dysplasia. In this case report, we present a male patient with symptoms of hoarseness, fatigue and abnormal bleeding all of which can be affiliated with methotrexate-induced hypoplastic myelodysplasia. As pancytopenia can be a lethal complication of MTX toxicity, it is important to monitor the therapy and dosage of methotrexate so that in case of any unforeseen development of a complication vital steps may be taken to diagnose and treat it in time. Regarding our patient, after thorough history taking and undergoing extensive hematological workup, the diagnosis of MTX-induced hypoplastic myelodysplasia was made. His symptoms improved on withholding the drug methotrexate from his active regimen and adding folinic acid and colony-stimulating factors.

Analysis of Mean Corpuscular Volume and Red Cell Distribution Width in Patients with Aplastic Anemia

To explore the characteristics of hemogram in patients with aplastic anemia (AA), especially mean corpuscular volume (MCV) and red cell distribution width (RDW). We examined the blood routine of 180 new-onset AA patients and used 166 patients with myelodysplastic syndrome (MDS) as controls. Among the 180 AA patients, 105 (58.3%) were diagnosed with severe AA (SAA), while 75 (41.7%) were diagnosed with non-severe AA (NSAA). Compared to MDS, patients with SAA generally had unfavorable hemogram, including significantly lower white blood cell (WBC), absolute neutrophil count (ANC), hemoglobin (Hb), platelet (PLT) and reticulocyte counts (RET). However, WBC, ANC and lymphocyte counts were higher in the NSAA group than in the MDS group; Hb and Ret were comparable between the two groups. 8.5% of SAA patients and 58.1% of NSAA patients presented with macrocytic anemia, whereas 25.7% of SAA and 64.0% of NSAA had a high RDW. In the MDS group, 54.7% of patients presented with macrocytic anemia, and 84.7% had increased RDW. WBC, ANC, PLT, and Ret in a high-RDW group (25.7% of SAA) were significantly higher than in a normal-RDW group (74.3% of SAA). Overall, most SAA patients exhibited normocytic-normochromic anemia, and their hemograms decreased more significantly; more than half of NSAA patients showed macrocytic-heterogeneous anemia, and their hemograms were similar to those of MDS. Patients with elevated RDW may have better residual bone marrow hematopoietic function than those with normal RDW but with more severe anemia.

Aplastic Anemia in Triple X Syndrome

Triple X syndrome is the most common sex chromosome aneuploidies (SCA) in females. Still, it is underdiagnosed because patients are usually without clear dysmorphism, and the syndrome is not associated with any significant congenital anomalies. We are reporting a case of a 5-year-old girl who presented with aplastic anemia, confirmed by a bone marrow aspiration and biopsy. Her complete workup showed that she has three copies of chromosome X, which, given the diagnosis of triple X syndrome, requires a supportive treatment but not a bone marrow transplant. Few cases of aplastic anemia with sex chromosome abnormalities have been reported. We are reviewing the triple X syndrome in different aspects of the presentation.

The role of inflammation in hematopoiesis and bone marrow failure: What can we learn from mouse models?

Hematopoiesis is a remarkable system that plays an important role in not only immune cell function, but also in nutrient transport, hemostasis and wound healing among other functions. Under inflammatory conditions, steady-state hematopoiesis switches to emergency myelopoiesis to give rise to the effector cell types necessary to fight the acute insult. Sustained or aberrant exposure to inflammatory signals has detrimental effects on the hematopoietic system, leading to increased proliferation, DNA damage, different forms of cell death (i.e., apoptosis, pyroptosis and necroptosis) and bone marrow microenvironment modifications. Together, all these changes can cause premature loss of hematopoiesis function. Especially in individuals with inherited bone marrow failure syndromes or immune-mediated aplastic anemia, chronic inflammatory signals may thus aggravate cytopenias and accelerate disease progression. However, the understanding of the inflammation roles in bone marrow failure remains limited. In this review, we summarize the different mechanisms found in mouse models regarding to inflammatory bone marrow failure and discuss implications for future research and clinical practice.