Regulatory T cells and CD20+ B cells in pediatric very severe aplastic anemia: possible clinical markers for evaluating the therapeutic efficacy and prognosis

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.

Reduced regulatory effects of bone marrow-derived mesenchymal stem cells on activated T lymphocytes and Th1/Th2 cytokine secretion in children with aplastic anemia

Acquired aplastic anemia (AA) is a recognized immune-mediated disorder and abnormally activated T lymphocyte-mediated bone marrow destruction is considered to be its main pathogenesis. Whether abnormal activation of T lymphocytes would also damage bone marrow-derived MSCs remains to be further studied. The aim of this study was to analyze the extent of T lymphocyte activation and the levels of Th1/Th2 cytokines of AA patients, and to explore the immunomodulatory effects of BM-MSCs on IL-2-stimulated T lymphocyte activation and cytokine production in vitro by means of transwell co-culture assay and flow cytometry measurement. The intermediate (CD25+) activated T cells were dominant in peripheral blood, while the early (CD69+) and late (HLA-DR+) activated T cells were predominant in bone marrow. Severe AA patients have an obviously higher proportion of CD3+CD8+CD69+ T cells than NSAA cases. The levels of IL-2 and IL-6 in AA patients were slightly elevated and INF-γ was mildly decreased in comparison with normal individuals. BM-MSCs derived from AA could not effectively inhibit the IL-2-induced activation of T cells with higher proportions of CD25+CD3+CD4+, CD69+CD3+CD4+ and CD25+CD3+CD8+ T cells after co-culture, and they showed a decreased ability to balance the Th1/Th2 cytokine production. Moreover, they had less robust osteogenic differentiation and more prone to adipogenic differentiation. We concluded that abnormally excessive T cell activation accompanied by abnormal cytokine secretion may impair the function of BM-MSCs in children with aplastic anemia.

Cluster analysis of lymphocyte subset from peripheral blood in newly diagnosed idiopathic aplastic anaemia patients

INTRODUCTION

Idiopathic aplastic anaemia (IAA) is a heterogeneous autoimmune disease characterised by pancytopenia and bone marrow failure. The objective of the study was to investigate the clusters of lymphocyte subset in newly diagnosed IAA patients and explore their correlation with clinical characteristics.

METHODS

A total of 124 newly diagnosed IAA patients were enrolled. Lymphocyte subset was detected by flow cytometry. Cluster analysis was conducted to identify subgroups of patients based on lymphocyte subset.

RESULTS

Cluster analysis classified patients into four distinctive subgroups: Cluster 1 (CD4⁺ T cells dominant), Cluster 2 (CD8⁺ T cells dominant), Cluster 3 (NK cells dominant) and Cluster 4 (B cells dominant). Patients in Clusters 1 and 4 suffered more severe disease status than ones in Clusters 2 and 3 (p = .013). And with it, patients in Cluster 2 had the highest white blood cell count, haemoglobin level, reticulocyte count and reticulocyte percentage, while patients in Cluster 3 had the lowest lymphocyte percentage and the highest neutrophil count (all p < .05). Unexpectedly, patients in Cluster 3 tended to have superior curative effect than ones in other clusters, an ordinal logistic regression analysis further confirmed the independent correlation between Cluster 3 and good response to treatment. Lymphocyte subset clustering may serve as a biomarker for assessing disease severity and treatment efficacy in newly diagnosed IAA patients.Key MessagesNewly diagnosed IAA patients could be classified into 4 distinctive subgroups with similar immune patterns by using cluster analysis of lymphocyte subset.Clusters of lymphocyte subset were closely correlated with disease severity and treatment response of IAA.Lymphocyte subset clustering may serve as a promising tool for assessing disease severity and treatment efficacy in newly diagnosed IAA patients.

Cyclosporine Monotherapy in Pediatric Patients With Non-severe Aplastic Anemia: A Retrospective Analysis

Objective

The management of children with non-severe aplastic anemia (NSAA) is undefined and the efficacies and benefits of immunosuppressive therapy remain inconsistent. The study aimed to investigate the efficacy of Cyclosporine (CsA) monotherapy for pediatric NSAA.

Methods

Clinical data of children with NSAA who had been treated with CsA monotherapy at the outpatient department of Beijing Children's Hospital, Capital Medical University, National Children's Medical Center from January 2017 to March 2021 was collected retrospectively. Patients who had been treated <1 years until the end of follow-up were excluded. Transfusion-independent NSAA was further divided into moderate NSAA and mild NSAA according to the degree of cytopenia. Progression was defined as the development of transfusion-dependent AA or SAA and relapse was considered when treatment failed after initial response.

Results

A total of 95 pediatric patients with NSAA were enrolled in this study with 49 (51.6%) patients confirmed as mild NSAA, 38 (40%) as moderate NSAA and 8 (8.4%) as transfusion-dependent NSAA. The median treatment time of CsA was 22 (12–44) months. The overall response rate (ORR) was 57.9%, with 30.5% CR and 27.4% PR. Unexpectedly, patients with mild NSAA acquired lowest ORR (46.9%), then patients with moderate NSAA (63.2%), while 8 patients who were transfusion-dependent all had an active response to CsA. The granulocyte and megakaryocyte response was 46.9 and 55.8% respectively, while the erythrocyte response rate was as low as 22.5%. Univariate analyses revealed that patients with lower platelet count and higher interleukin 10 level predict an active response to CsA while higher level of fetal hemoglobin (HbF) tended to be a negative factor. Data of Treg cells before and after 1 year's treatment was available in a total number of 40 patients. Paired comparison found that the percentage of Treg cells in CD4+ T cells was decreased after 1 year's treatment of CsA (6.78 ± 2.72 vs. 5.23 ± 2.06, P = 0.001),both in responders and non-responders. The degree of decline in Treg cells between two distinctive response groups had no significant difference (P>0.05). With a median follow-up time of 22 months, 10.9% of responders relapsed and maintained NSAA while 27.5% of non-responders progressed to SAA or became transfusion-dependent. The overall progression rate was 11.6%.

Conclusion

CsA monotherapy had heterogeneous effects in the treatment of children NSAA Treatment approaches should be hierarchical and individual in clinical. Patients with lower platelet count and higher interleukin 10 level predicted an active response to CsA. While higher level of fetal hemoglobin (HbF) tended to be a negative factor. The percentage of Treg cells in CD4+ T cells was decreased broadly after treatment.

Effects of Shikonin on the Functions of Myeloid Dendritic Cells in a Mouse Model of Severe Aplastic Anemia

This study is aimed at investigating the effects of shikonin, a pyruvate kinase M2 (PKM2) inhibitor, on the functions of myeloid dendritic cells (mDCs) in a mouse model of severe aplastic anemia (AA) generated by total body irradiation and lymphocyte infusion. Flow cytometry and qPCR were used to determine the proportions of PKM2+ mDCs and other immune indicators in the AA mice. Glucose consumption level, pyruvate generation level, and ATP content were used to determine the level of glycolytic metabolism in the mDCs. The survival rates of AA mice were evaluated after the administration of shikonin or the immunosuppressive agent cyclosporin A. The AA mice displayed pancytopenia, decreased CD4+/CD8+ cell ratio, increased perforin and granzyme levels in CD8+ cells, increased costimulatory CD80 and CD86 expressions, and inadequate regulatory T cell number. In vivo animal experiments showed that the shikonin-mediated inhibition of the PKM2 expression in mice was associated with high survival rates. In addition, the administration of cyclosporin A or shikonin decreased the expression of cytotoxic molecules and costimulatory CD80 and CD86 on CD8+ cells. Taken together, the results of this study indicated that shikonin could inhibit the activation and proliferation of mDCs as well as the activation of downstream cytotoxic T cells by reducing the PKM2 level in mDCs.