Mouse Model Of Aplastic Anemia Research Articles

Chinese herbal formula, modified Guilu Erxian glue, alleviates apoptosis of hematopoietic stem cells by regulating SLAM-SAP signal pathway in aplastic anemia mice model

Ethnopharmacological relevanceGuilu Erxian Glue (GEG) and Danggui Buxue Tang (DBT) are traditional Chinese herbal formulas. According to the theory of traditional Chinese medicine, the combination of those two formulas (Modified Guilu Erxian Glue, MGEG) has the effects of tonifying the kidney and producing blood, was usually used to treat bone marrow failure diseases, including aplastic anemia (AA). Aim of the studyT lymphocytes play a crucial role in the disease pathogenesis and progression of AA. Our preliminary results confirmed that GEG can improve the damage of hematopoietic stem cells in mice, while DBT can reduce the proliferation and differentiation of T lymphocytes and inhibit the production of IFN-γ. We hypothesized that the combination of those two herbal formulas could inhibit immune attack and restore hematopoietic function through multiple mechanisms. In this study, we aim to study the curative effect of MGEG on regulating the expression of Signal lymphocyte activating molecule (SLAM), an activation-related molecule in T lymphocytes, thereby suppressing the immune function of T cells and decelerating the damage to hematopoietic stem cells. Materials and methodsHigh-performance liquid chromatography-electrospray ionization/mass spectrometry system was used to identify the components of the MGEG formulation. Induction of aplastic anemia mouse model by injecting allogeneic lymphocyte suspension into BABL/c mice after ionizing radiation. Cyclosporine A (CsA) was used as a positive control drug. Flow cytometry was used to detect the number and apoptosis rate of hematopoietic stem cells in the bone marrow. Enzyme-linked immunosorbent assay was performed to measure the levels of IFN-γ and TNF-α. Immunofluorescence staining was used to assess the expression of T-bet and SLAM-SAP. Western Blot was conducted to examine the expression of activation-related molecules in T lymphocytes and proteins related to the Fas signal pathway. Hematoxylin-eosin staining was performed to observe pathological changes in the bone marrow tissue. Wright-Giemsa staining was utilized to evaluate alterations in the cellular composition and basic structure of the bone marrow cells (BMCs). Transmission electron microscopy was employed to observe changes in the structure and morphology of hematopoietic stem cells. The hematology analyzer was used to detect peripheral blood parameters. ResultsTwenty-three different components were identified in MGEG. After MGEG treatment, the expression levels of Fyn and SLAM-SAP binding were increased in AA mice, while the expression levels of T-bet were decreased and the secretion of IFN-γ was reduced significantly. Additionally, MGEG also could downregulate the protein levels of Fas, caspase-3, and cleaved caspase-3 in AA mice. ConclusionMGEG could attenuate the production of IFN-γ by promoting the SLAM-SAP signal pathway to regulate the generation and distribution of T-bet in T cells. Additionally, it suppresses apoptosis of HSCs through intervention in the Fas-dependent pathway, thereby mitigating immune-mediated damage to HSCs.

Dioscin alleviates aplastic anemia through regulatory T cells promotion

ABSTRACT Objectives: Aplastic anemia (AA) is one of the immune-mediated bone marrow failure disorders caused by multiple factors, including the inability of CD4 + CD25 + regulatory T cells (Tregs) to negatively regulate cytotoxic T lymphocytes (CTLs). Dioscin is a natural steroid saponin that has a similar structure to steroid hormones. The purpose of this study is to look into the effect of Dioscin on the functions of CD4 + CD25+ Tregs in the AA mouse model and explore its underlying mechanism. Methods: To begin with, bone marrow failure was induced through total body irradiation and allogeneic lymphocyte infusion using male Balb/c mice. After 14 consecutive days of Dioscin orally administrated, the AA mouse model was tested for complete blood counts, HE Staining of the femur, Foxp3, IL-10 and TGF-β. Then CD4 + CD25+ Tregs were isolated from splenic lymphocytes of the AA mouse model, Tregs and the biomarkers and cytokines of Tregs were measured after 24 h of Dioscin intervention treatment in vitro. Results: Dioscin promotes the expression of Foxp3, IL-10, IL-35 and TGF-β, indicating its Tregs-promoting properties. Mechanistically, the administration of Dioscin resulted in the alteration of CD152, CD357, Perforin and CD73 on the surface of Tregs, and restored the expression of Foxp3. Conclusion: Dioscin markedly attenuated bone marrow failure, and promoted Tregs differentiation, suggesting the maintenance of theimmune balance effect of Dioscin. Dioscin attenuates pancytopenia and bone marrow failure via its Tregs promotion properties.

PRMT5 regulates epigenetic changes in suppressive Th1-like iTregs in response to IL-12 treatment.

Induced regulatory T cells (iTregs) are a heterogeneous population of immunosuppressive T cells with therapeutic potential. Treg cells show a range of plasticity and can acquire T effector-like capacities, as is the case for T helper 1 (Th1)-like iTregs. Thus, it is important to distinguish between functional plasticity and lineage instability. Aplastic anemia (AA) is an autoimmune disorder characterized by immune-mediated destruction of hematopoietic stem and progenitor cells in the bone marrow (BM). Th1-like 1 iTregs can be potent suppressors of aberrant Th1-mediated immune responses such as those that drive AA disease progression. Here we investigated the function of the epigenetic enzyme, protein arginine methyltransferase 5 (PRMT5), its regulation of the iTreg-destabilizing deacetylase, sirtuin 1 (Sirt1) in suppressive Th1-like iTregs, and the potential for administering Th1-like iTregs as a cell-based therapy for AA. We generated Th1-like iTregs by culturing iTregs with IL-12, then assessed their suppressive capacity, expression of iTreg suppression markers, and enzymatic activity of PRMT5 using histone symmetric arginine di-methylation (H3R2me2s) as a read out. We used ChIP sequencing on Th1 cells, iTregs, and Th1-like iTregs to identify H3R2me2s-bound genes unique to Th1-like iTregs, then validated targets using CHiP-qPCR. We knocked down PRMT5 to validate its contribution to Th1-like iTreg lineage commitment. Finally we tested the therapeutic potential of Th1-like iTregs using a Th1-mediated mouse model of AA. Exposing iTregs to the Th1 cytokine, interleukin-12 (IL-12), during early events of differentiation conveyed increased suppressive function. We observed increased PRMT5 enzymatic activity, as measured by H3R2me2s, in Th1-like iTregs, which was downregulated in iTregs. Using ChIP-sequencing we discovered that H3R2me2s is abundantly bound to the Sirt1 promoter region in Th1-like iTregs to negatively regulate its expression. Furthermore, administering Th1-like iTregs to AA mice provided a survival benefit. Knocking down PRMT5 in Th1-like iTregs concomitantly reduced their suppressive capacity, supporting the notion that PRMT5 is important for the superior suppressive capacity and stability of Th1-like iTregs. Conclusively, therapeutic administration of Th1-like iTregs in a mouse model of AA significantly extended their survival and they may have therapeutic potential.

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.

Network pharmacology and experimental verification of the potential mechanism of Er-Xian decoction in aplastic anemia

To investigate the potential mechanism of Er-Xian decoction (EXD) in treating aplastic anemia (AA), the active components of EXD were screened by the Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform (TCMSP), and the targets of the components were predicted by the Swiss Target Prediction database. AA targets were collected from the GeneCards, OMIM, DisGeNET, PharmGKB, DrugBank, and TTD databases, the intersection of AA targets and EXD targets was calculated, and an herb-component-target network was constructed by Cytoscape 3.7.2 software. The STRING database was used for protein‒protein interaction (PPI) analysis, and Cytoscape 3.7.2 software was used to construct a PPI network and perform topology analysis. The core targets were imported into the DAVID database for gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses. The molecular docking software AutoDock was used to measure the affinity between active components and key targets. Finally, we established a mouse model of AA and verified the key targets and signaling pathways of EXD by RT‒PCR, ELISA and Western blot analysis. A total of 53 active components were screened from EXD, 2516 AA-related targets were collected, and 195 common targets were obtained. An herb-component-target network and a PPI network were successfully constructed, and 36 core targets were selected from the PPI network. The main active components of EXD include luteolin, kaempferol, berberine, etc., and key targets include PIK3CA, AKT1, STAT3, etc. GO functional enrichment analysis showed that cell components, molecular functions and biological processes with significant correlations were macromolecular complexes, protein serine/threonine/tyrosine kinase activity and protein phosphorylation, respectively. KEGG pathway analysis showed that the pathways with significant correlations included the PI3K-Akt signaling pathway and JAK-STAT signaling pathway. Molecular docking results showed that the tested key targets had good affinity for the corresponding active components. In AA mice, we found that EXD significantly increased white blood cell count, red blood cell count, platelet count and hemoglobin levels, increased mRNA levels of PIK3CA, PIK3CD, AKT1, JAK2, STAT3 and MAPK1, and promoted phosphorylation of PI3K, AKT, ERK1/2 and STAT3. In summary, EXD acts on PI3K, AKT, STAT3 and other targets through berberine, luteolin, quercetin and other components to regulate the PI3K-Akt pathway, JAK-STAT pathway and other pathways, thus exerting its therapeutic effect on AA. This study explained the Chinese medicine theory of treating AA with EXD by tonifying kidney-yang and provides a scientific basis for the use of EXD in treating AA.

Umbilical cord-derived mesenchymal stem cells cultured in the MCL medium for aplastic anemia therapy

BackgroundMesenchymal stem cells (MSCs) are a class of adult stem cells with self-renewal and multidirectional differentiation potential that may be a treatment for aplastic anemia (AA).MethodUmbilical cord-derived MSCs were cultured in three media (Mesencult-XF, MCL, and StemPro MSC SFM CTS). HGF, PGE2, ANG-1, TGF-β1, IFN-γ, and TNF-α were detected using ELISA. The AA mouse model was built via post-irradiation lymphocyte infusion. After different treatments, routine blood, VEGF, and Tregs were detected every week. On day 28, all mice were killed, and their femurs were stained with HE.ResultsUmbilical cord-derived MSCs cultured in the three media all conformed to the general characteristics of MSCs. HGF secreted by MSCs in the Mesencult-XF, and MCL was greater than that in the StemPro MSC SFM CTS; ANG-1 and TGF-β1 in the MCL were more than that in Mesencult-XF and StemPro MSC SFM CTS; PGE2 in the MCL and StemPro MSC SFM CTS was more than that in the Mesencult-XF. MSCs in the MCL and StemPro MSC SFM CTS inhibited IFN-γ and TNF-α more than those in the Mesencult-XF. The peripheral blood cell in the AA groups was at a low level while that in the MSC group recovered rapidly. The Treg ratio and VEGF level in the MSC group were higher than those in the AA group. The bone marrow (BM) recovered significantly after MSC infusion.ConclusionMSCs in the MCL were advantageous in supporting hematopoiesis and modulating immunity and had the potential for effective treatment of AA.

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.

Dioscin Regulating Bone Marrow Apoptosis in Aplastic Anemia.

BackgroundAplastic anemia (AA), a disease of bone marrow failure, is caused by CD8+T mediated apoptosis of hematopoietic cells. However, traditional immunosuppressive therapy (IST) has severe liver and kidney toxicity and even cannot achieve the expected therapeutic effect in some patients.PurposeOur study is aimed to investigate the effect and mechanism of dioscin (DNS) for treating AA.MethodsBriefly, we established and evaluated the AA mouse model, DNS and positive control drugs were used for intervention treatment. After 14 days of intervention, femoral bone marrow pathology, bone marrow mononuclear cells (BMMCs) apoptosis rate, bone marrow CD34+ cell surface Fas (CD95) expression and Fas signaling pathway key proteins were detected.ResultsAfter the establishment of the AA mouse model, the number of peripheral blood cells including granulocytes, erythrocytes, hemoglobin, platelets and reticulocytes in the AA group model was significantly decreased compared with the group control (P < 0.01). The degree of bone marrow hyperplasia in the sternum and femur is extremely low. After different drug interventions, compared with the group model, the number of peripheral blood cells in the AA mice rebounded significantly in group DNS (P < 0.01). Not only that the apoptosis rate of BM-MCs decreased (P < 0.01), meanwhile, the CD95 molecule expressed on the CD34+ bone marrow cells had a significant decline (P < 0.01), and the expression level of the key proteins of Fas signaling pathway was also significantly decreased (P < 0.01).ConclusionDNS recovered the peripheral pancytopenia and bone marrow failure in AA mice. DNS reduced the key protein of Fas signaling pathway level to inhibit apoptosis of bone marrow cells to treat AA.

A mouse model of irradiation and spleen-thymus lymphocyte infusion induced aplastic anemia

ABSTRACT Objectives The immune-induced aplastic anemia (AA) mouse model has been used for the study of AA. However, there were no uniform conditions for establishing a model and no assessment of immunological homeostasis. Our study aimed to identify the conditions of establishing a model and assess the AA model in immunology and pathology. Methods We induced an AA mouse model by the combination between sublethal irradiation and spleen-thymus lymphocyte infusion. The success of establishing the AA model was identified by blood routine tests and pathology of bone marrow. The frequency of Th17 and Treg cells was measured by flow cytometry. The frequency of CD34+ and CD41+ cells was detected by immunohistochemical technique.IL-6, IL-8, IL-17, TNF-α and IFN-γ were evaluated by ELISA. Results The 137Cs sublethal irradiation (5 Gy) and spleen-thymus lymphocyte infusion (5 106) induced the AA mouse model successfully. The AA mice had a long lifetime and manifested pancytopenia and bone marrow failure. The percentage of Th17 cells increased and the percentage of Treg cells decreased distinctly in AA mice. The area of hematopoietic tissues and count of CD34+ cells and CD41+ cells were significantly reduced in AA mice.The level of cytokines, IL-6, IL-8, IL-17, TNF-α and IFN-γ, was increased significantly in peripheral blood and bone marrow. Conclusion Our data suggest that the improved AA mouse model conforms to the diagnosis standard of AA and simulates the immune internal environment of human AA. The AA mouse model has a longer lifetime and unbalances of Th17/Treg cells caused the destruction of CD34+ cells and CD41+ cells, which was immune-mediated pathogenesis to adapt to long-term research.

Kinetics of immune activated T cells in aplastic anemia mouse model

目的探索再生障碍性贫血（AA）小鼠模型中供者来源T细胞不同时间点动力学变化。方法构建AA小鼠模型，分别于不同时间点采用流式细胞术测定模型小鼠脾脏与骨髓内供者T细胞比例、活化分子表达、细胞周期及功能亚群，评估不同时期T细胞功能状态。结果①半致死剂量照射联合主要组织相容性抗原（MHC）半相合的淋巴结细胞输注成功构建T细胞免疫介导的AA小鼠模型。②AA小鼠脾脏中供者T细胞从移植第3天后开始明显浸润，并逐渐出现CD4+/CD8+比例倒置，第5天开始进入骨髓，以CD8+细胞浸润为主。③CD69在供者CD4+细胞中表达高峰晚于CD8+细胞，CD25在CD4+细胞与CD8+细胞中表达水平的变化趋势相同，但在CD8+细胞中的表达高于CD4+细胞。④脾脏内供者CD4+细胞S/G2/M期比例在移植后第3天即达高峰，约12％，而CD8+细胞中S/G2/M期比例在移植后第5天达高峰，约20％，且两者在进入骨髓后S/G2/M期比例均再次升高，但移植第3天后其比例在脾脏与骨髓CD8+细胞中持续高于CD4+细胞。⑤脾脏内免疫活化的T细胞经历短暂的中枢记忆T细胞（TCM）阶段后迅速分化为效应记忆T细胞（TEM），进入骨髓后部分TEM分化为效应细胞进一步发挥效应功能。结论AA小鼠模型中供者T细胞进入异体后迅速活化，5天内达增殖高峰，并完成向TEM细胞的分化，5天后开始进入骨髓进一步增殖损伤造血。

The characterization analysis of pathogenic T cells in immune-mediated aplastic anemia mouse model

目的通过DsRed小鼠淋巴细胞输注加全身辐照（TBI）建立免疫介导的再生障碍性贫血（AA）C.B10-H2b/LilMcd (C.B10)小鼠模型，分析C.B10 AA小鼠模型中病理性T细胞在不同器官的动态归巢过程及特征。方法通过异体淋巴细胞输注加TBI建立AA小鼠模型，以TBI组为对照，分析外周血细胞和骨髓单个核细胞数，验证造模效果。在造模的第3、6、9、12天，处死小鼠并收集骨髓、脾脏、淋巴结和胸腺单个核细胞，流式细胞术分析DsRed+ T细胞的动态变化及效应记忆T细胞（TEM）、中央记忆T细胞（TCM）、初始T细胞（naïve T）和效应T细胞（TEFF）的比例。PCR Array分析AA小鼠不同组织内DsRed+病理性T细胞活化相关基因的表达谱。结果与TBI组相比，AA组小鼠在造模第9、12天出现严重骨髓衰竭，第12天时骨髓有核细胞数、外周血细胞数均显著减少（P值均<0.05）。AA组小鼠骨髓、脾脏、淋巴结内DsRed+ T细胞比例随时间增加而增加。骨髓中的DsRed+ T细胞比例在第3、6天低于脾脏与淋巴结，但在第12天时高于脾脏与淋巴结（P值均<0.05）。整个骨髓衰竭形成过程中，胸腺中DsRed+ T细胞比例均最低。在第12天时，AA小鼠骨髓、淋巴结和脾脏单个核细胞中，DsRed+CD3+CD4+ T细胞比例分别为（91.38±2.10）％、（39.78±6.98）％、（67.87±12.77）％，三者之间两两比较均有统计学意义（P值均<0.05）；DsRed+CD3+CD8+ T细胞比例分别为（98.21±1.49）％、（94.06±4.20）％、（96.29±1.23）％，差异均无统计学意义（P值均>0.05）。第9、12天，AA组小鼠骨髓中几乎所有的DsRed+CD4+ T或DsRed+CD8+ T细胞均为TEM，而淋巴结中包括TEM、TCM以及naïve T。PCR Array结果显示：骨髓中DsRed+CD4+或DsRed+CD8+ T细胞中CD38、IFN-γ、LAG3、CSF1、SPP1及TNFSF13B表达增高，但 DsRed+CD4+ T细胞中FOXP3、CTLA4表达降低。结论DsRed小鼠淋巴细胞输注可导致C.B10小鼠发生骨髓衰竭，并可以在该AA模型小鼠中追踪DsRed+病理性T细胞。在C.B10 AA模型小鼠体内，DsRed+CD8+和DsRed+CD4+ T细胞先归巢到脾脏与淋巴结，在其中扩增分化，最终转运至骨髓并转化为TEM。胸腺对异体T细胞的归巢过程更具抵抗性，提示胸腺在免疫介导AA模型的骨髓衰竭过程中可能是一个免疫豁免部位。在C.B10 AA模型小鼠的骨髓衰竭形成过程中，归巢到骨髓的DsRed+病理性T细胞较迁移到脾脏与淋巴结的细胞具有更强的免疫活性，而免疫抑制活性则减弱。

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.

Bushen Jianpi Quyu Formula Alleviates Myelosuppression of an Immune-Mediated Aplastic Anemia Mouse Model via Inhibiting Expression of the PI3K/AKT/NF-κB Signaling Pathway.

Bushen Jianpi Quyu Formula (BSJPQYF), an experienced formula, has been used to treat aplastic anemia (AA) more than three decades. To determinate the effect of BSJPQYF on AA, we constructed an immune-mediated AA mouse model. All mice were divided into four groups: control, model, low dose (0.85 g/mL), and high dose (1.7 g/mL BSJPQYF) group. They were administered with different concentrations of BSJPQYF or normal saline for 14 days. Besides, components of BSJPQYF were analyzed by electrospray ionization and mass spectrometry (ESI-MS). Subsequently, mouse peripheral blood and femurs were collected, and bone marrow mesenchymal stem cells (BMSCs) were isolated by fluorescence-activated cell sorting (FACS). Among them, tumor necrosis factor-α (TNF-α), transforming growth factor-β (TGF-β), and interferon-γ (IFN-γ) were measured by ELISA assay, PI3K, AKT, p-AKT, NF-κB, p-NF-κB, TNF-α, and cleaved caspase-3 proteins were detected by western blot. Compared with standard compounds, we identified three compounds of BSJPQYF, namely, icariin, kaempferol and tanshinone iia, as potentially effective compounds for the treatment of AA. Through an in vivo study, we found the administration of BSJPQYF in high dose for 14 days could significantly increase peripheral blood count and bone marrow (BM) cells, meanwhile decrease TNF-α, TGF-β, and IFN-γ levels. Besides, it could suppress the protein expression of PI3K and the phosphorylation of AKT and NF-κB to restrict the protein expression of TNF-α, eventually reduce the protein expression of cleaved caspase-3. This study demonstrated the therapeutic effects of BSJPQYF in AA, which could alleviate myelosuppression through inhibiting the expression of the PI3K/AKT/NF-κB signaling pathway.

Insufficient Phosphorylation of STAT5 in Tregs Inhibits the Expression of BLIMP-1, Leading to a Lack of Tregs in Pediatric Aplastic Anemia

Aplastic anemia (AA) is a group of bone marrow failure diseases characterized by three-line blood cell reduction and decreased myeloproliferation. It is believed that T cell immune disorder is the leading cause of the disease, especially the number and functional damage of regulatory T cells (Tregs). BLIMP-1 is a transcription factor encoded by PRDM1 gene, which is indispensable for Tregs. The expression of BLIMP-1 is mainly induced by the IL-2/STAT5 signaling pathway. However, the level of phosphorylation of STAT5 and the expression of BLIMP-1 in Tregs from patients with AA has not been revealed, and the mechanism of Tregs damage in AA has not yet been clarified. In the present study, we collected peripheral blood from 10 newly diagnosed AA children and 10 age-matched healthy donors. We observed that the ratio of Tregs/lymphocytes and Tregs/CD4 + T cells decreased significantly in AA patients, compared with healthy controls by flow cytometry. In addition, we found significantly elevated levels of inflammatory cytokines IL-2, IL-6, and IFN-γ, but decreased levels of anti-inflammatory cytokines IL-10 and TGF-β in plasma of children with AA, compared with healthy controls. Quantitative real-time PCR showed decreased transcriptional level of BLIMP-1 in peripheral blood mononuclear cells (PBMC) from children with AA, compared with healthy donors. We used flow cytometry to detect the protein level of BLIMP-1 in Tregs and found that the level of BLIMP-1 in Tregs in the peripheral blood of children with AA was significantly lower than that of healthy donors. The correlation analysis showed that the percentage of BLIMP-1 + Tregs was positively correlated with the ratio of Tregs/CD4 + T cells (r=0.829, p＜0.001), the plasma level of IL-10 (r=0.492, p=0.027), and TGF-β (r=0.482, p=0.030), suggesting that low expression level of BLIMP-1 in Tregs may lead to decreased number of Tregs in peripheral blood and declined levels of IL-10 and TGF-β in children with AA. When stimulated IL-2, the level of pSTAT5 in CD4 + T cells of children with AA was significantly reduced compared with that of healthy donors. The level of pSTAT5 in CD4 + T cells was also positively correlated with the ratio of Tregs/CD4 + T cells (r= 0.575, p= 0.008) and the expression of BLIMP-1 in Tregs (r=0.693, p＜0.0001)，suggesting that STAT5 signal is poorly activated in pediatric AA, and it may be an important cause for the low expression of BLIMP-1 in Tregs and the decrease in the number of Tregs in children with AA. Furthermore, we constructed an AA mouse model by co-administering IFN-γ and busulfan for 10 consecutive days. These mice exhibited decreased ratio of Tregs/CD4 +T cells in the spleen and lower BLIMP-1 in Tregs, compared with controls. Also, we isolated Tregs with immunomagnetic beads from spleens of mice and observed that the level of IL-2-stimulated pSTAT5 was lower in isolated Tregs from AA mice than controls. These phenotypes were partially rescued by intervention of IL-2-JES6-1, an antibody complex tends to promote the proliferation of Tregs in mice, while inhibiting the proliferation of effector T cells. IL-2-JES6-1 increased the level of pSTAT5 and the expression of BLIMP-1 in Tregs from spleen of the AA mice, and elevated the ratio of Tregs/CD4 + T cells in the spleen. In conclusion, we found that Tregs from AA patients have impaired phosphorylation of STAT5 and insufficient expression of BLIMP-1, which may contribute to the pathogenesis of AA. DisclosuresNo relevant conflicts of interest to declare.

Reversal of Aplastic Anemia By Mesenchymal Stem Cell-Derived Extracellular Vesicles

Aplastic anemia is a disease of bone marrow failure. Aplastic anemia remains a challenging disease as far as etiology and therapeutic approaches. Extracellular vesicles (EVs) have been studied for many years. These were initially felt to be cell junk largely from platelets and erythrocytes. But, more recently, intense interest has been focused on their potential for altering cell fate and reversing tissue injury. Vesicles derived from mesenchymal stem cells (MSC) have been shown to affect the phenotype and induce healing of many different cell types. Our recent published work has shown that human or murine MSC-EV treatment dramatically reversed radiation damage to bone marrow both in vitro and in vivo by inhibition of DNA damage and apoptosis. In this study, we evaluated whether human MSC-EVs could reverse marrow failure in a Busulfan induced aplastic anemia mouse model. We have carried out studies on Busulfan (BU) induced marrow aplasia by administering Busulfan in doses of 9.25 mg/kg intraperitoneally (9 times over 20 days) to induce bone marrow aplasia in female Balb/cByJ mice. Mice were then infused with 4x108 human MSC-EVs at 1, 2 and 3 days after the final BU dose. We observed that the human MSC EV treatment significantly prolonged survival in these mice. 50% of the BU treated mice died by 30 days after BU injection, whereas only 30% of EV-injected mice died by this time. The mice were sacrificed to harvest WBM cells and peripheral blood for cell count at 10 days after the final BU dose. There were significant decreases in marrow cellularity from tibiae and femurs and complete blood count (CBC) including RBC, WBC, HBG and PLT in BU treated mice compared to vehicle control mice. The vesicle treatment led to a statistically significant (p<0.05) increase in bone marrow cell count with the average of 3.30 x106 ±0.46 x106 cells /tibia and femur for the vesicle treated mice compared to 2.05 x106 ± 0.46 x 106 cells for the non-vesicle treated mice. The restoration growth of bone marrow stem cells was further confirmed by WBM proliferation assessment in cell culture. We further investigated the effect of MSC-EVs on the microRNA expression in bone marrow cells from Busulfan induced aplastic anemia mice by microRNA realtime PCR array. 151 microRNAs were altered by Busulfan treatment. 88 showed partial or complete reversal of these alterations after EV treatment. In summary, our data suggest that MSC-EV treatment could partially reverse Busulfan induced marrow failure at early time points. The reversal of the Busulfan induced chronic bone marrow failure by MSC-EVs needs further investigation. DisclosuresNo relevant conflicts of interest to declare.

Ginsenoside Rg1 can restore hematopoietic function by inhibiting Bax translocation-mediated mitochondrial apoptosis in aplastic anemia

The present study investigated, the anti-apoptotic activity of Ginsenoside Rg1 (Rg1) via inhibition of Bax translocation and the subsequent recovery of hematopoietic function. Mitochondrial apoptosis in bone marrow mononuclear cells (BMNCs) was observed in aplastic anemia (AA) patients. To establish a mouse model of AA, BALB/c mice were transplanted with lymph node cells from DBA/2 donor mice via vein injection after treatment with Co60 γ-radiation. After treatment with Rg1 for 14 days, the peripheral blood and Lin–Sca-1 + c-Kit + (LSK) cell counts of the treated group were increased compared with those of the untreated model mice. In in vivo and in vitro tests of LSKs, Rg1 was found to increase mitochondrial number and the ratio of Bcl-2/Bax and to decrease damage to the mitochondrial inner and outer membranes, the mitochondrial Bax level and the protein levels of mitochondrial apoptosis-related proteins AIF and Cyt-C by decreasing the ROS level. Rg1 also improved the concentration–time curve of MAO and COX and levels of ATP, ADP and AMP in an in vitro test. In addition, high levels of Bax mitochondrial translocation could be corrected by Rg1 treatment. Levels of markers of mitochondrial apoptosis in the Rg1-treated group were significantly better than those in the AA model group, implying that Rg1 might improve hematopoietic stem cells and thereby restore hematopoietic function in AA by suppressing the mitochondrial apoptosis mediated by Bax translocation.

Stanozolol and Danazol Have Different Effects on Hematopoiesis in the Murine Model of Immune-Mediated Bone Marrow Failure.

Background: Stanozolol and danazol are widely used in the treatment of aplastic anemia; however, their mechanisms of action are unclear.Methods: Bone marrow mononuclear cells from 10 patients newly diagnosed with aplastic anemia and 10 healthy volunteers were collected and cultured together with stanozolol, danazol, or blank control separately for marrow colony assays. K562 cell lines that had been incubated with stanozolol, danazol, or blank control were tested for erythroid or megakaryocytic differentiation. Meanwhile, CB6F1/Crl mice were injected with 1 × 106 C57BL/6 donor-originated lymphocytes after irradiation with 5 Gy total body irradiation to establish a model for immune-mediated bone marrow failure (aplastic anemia mouse model). Mice with aplastic anemia were treated with cyclosporin A monotherapy, cyclosporin A in combination with stanozolol, and cyclosporin A in combination with danazol for 30 days. Peripheral blood cell counts once a week and bone marrow colony assays at the end of 1 month were performed. The proportion of T cell subsets, level of inflammatory factors, erythropoietin, and thrombopoietin were detected before and after treatment. The levels of erythropoietin receptors on bone marrow mononuclear cells after treatment were tested using western blotting.Results: In the ex vivo experiments, the number of burst-forming units-erythroid; colony-forming units-granulocyte and macrophage; and colony-forming units-granulocyte, erythrocyte, monocyte, and megakaryocyte in the patients with aplastic anemia were significantly lower than that in the normal controls (P < 0.05). However, the number of colonies and mean fluorescence intensity of CD235a or CD41 expression in the harvested cultured cells were not significantly different among the different treatment groups in the patients with aplastic anemia, normal controls, and K562 cell lines. These results show that stanozolol and danazol produce no direct hematopoiesis-stimulating effects on progenitor cells. In the in vivo experiment, the mice with aplastic anemia treated with cyclosporin A and danazol exhibited the most rapid recovery of platelet; the platelet count returned to normal levels after 3 weeks of treatment, which was at least 1 week earlier than in the other groups. In contrast, mice treated with cyclosporin A and stanozolol exhibited the highest hemoglobin level at the end of treatment (P < 0.05). Bone marrow colony assays at 30 days showed that the number of burst-forming units-erythroid was the highest in mice treated with cyclosporin A and stanozolol, while the number of colony-forming units-granulocyte and macrophage was the highest in those treated with cyclosporin A and danazol. Compared to cyclosporin A monotherapy, additional stanozolol and danazol can both increase the level of regulatory T cells and upregulate interleukin-10, inhibiting the expression of tumor necrosis factor-α (P < 0.05). However, IL-2 was more effectively reduced by danazol than by stanozolol (P < 0.05). The cyclosporin A- and stanozolol-treated mice showed higher serum erythropoietin (corrected by hemoglobin level) and higher erythropoietin receptor levels in bone marrow mononuclear cells than the other groups (P < 0.05).Conclusions: Neither stanozolol nor danazol directly stimulated hematopoiesis in vitro. However, in vivo, stanozolol may exhibit an advantage in improving erythropoiesis, while danazol may induce stronger effects on platelets. Both danazol and stanozolol exhibited immunosuppressive roles. Stanozolol could enhance the secretion of erythropoietin and expression of erythropoietin receptor in bone marrow mononuclear cells.

Optimization of Mouse Model of Aplastic Anemia Induced by Pan T Lymphocytes Combined with Irradiation

To establish the acquired aplastic anemia mouse model through the X-ray irradiation in combination with lymphocytes injection. AA Group: the purified Pan T lymphocytes from the spleen of C57BL/6J mice were enriched and injected to the mice through tail vein(5×106), the CB6F1 mice were exposed to 3,4 and 5 Gy X-ray irradiation; TBI Group: the CB6F1 mice were exposed to 3,4 and 5 Gy X-ray irradiation, and were injected with the same volume of PBS buffer; Control group: the CB6F1 mice were only injected with the same volume of PBS buffer. The peripheral blood routine was examined and the number of nucleated cells in bone marrow were calculated；the hematopoiesis changes in bone marrow was examined；flow cytometry was used to examine the distribution of T lymphocytes in bone marrow, and it also used to examine the apoptosis of bone marrow cells and the differentiation of spleen T lymphocytes. Compared with 4, 5 Gy irradiated mice in AA groups, the survival time of 3 Gy irradiated AA groups was significantly prolonged. 3, 4 and 5 Gy X-ray irradiation combined with Pan T lymphocyte injection could successfully induced severe reduction of red blood cells, blood neutrophils, and platelets, severe reduction of bone marrow nucleated cells, severe bone marrow hematopoietic failure, and the significant expansion of T lymphocytes ratio in the bone marrow. CD4+ and CD8+ T cells were both increased, but mainly on CD8+ T cells, and could promote the differentiation of T cells from naïve T cells to effector memory T cells. 3, 4 and 5 Gy X-ray irradiation combined with 5×106 pan-T cell injection could successfully induce acquired aplastic anemia through T lymphocyte hyperfunction. Compared with 4, 5 Gy irradiated AA group, the 3 Gy irradiated AA group shows significantly longer survival time, and the peripheral blood routine profile closely resembles the clinical manifestations of AA patients.

Mesenchymal stem cell-derived extracellular vesicles conditionally ameliorate bone marrow failure symptoms in an immune-mediated aplastic anemia mouse model.

Acquired forms of Aplastic anemia (AA) are characterized by T cell-mediated immune disease resulting in bone marrow (BM) failure and marrow hypoplasia. In these cases, it is a major challenge to modulate autoreactive T cell activity and thereby decrease the pro-inflammatory cytokine storm. Emerging evidence indicates that extracellular vesicles derived from mesenchymal stem cells (MSC-EVs) control and modulate immunity. The therapeutic potential of MSC-EVs has not been investigated in acquired AA. Hence, in this study, we constructed an AA mice model through irradiation and splenocyte infusion to test the benefits of hypoxic MSC-EVs (Hx-EVs) and normoxic MSC-EVs (Nx-EVs). We found that MSC-EVs treatment significantly prolonged the survival rate and increased the platelet (PLT) counts of the AA mice. Immunohistochemical staining and colony assay confirmed amelioration of hypoplasia in the BM and increased numbers of hematopoietic stem cells (HSCs). These effects of MSC-EVs were mediated by T cell suppression and inhibition of interferon-gamma (IFN-γ) and tumor necrosis factor-alpha (TNF-α) production in the AA mouse model. In addition, an in vitro study revealed that MSC-EVs led to reduced IFN-γ and TNF-α levels and there was an association with decreased splenocyte viability. Previous studies examined the diagnostic and prognostic values of microRNAs (miRNAs) in AA and identified miR-199a, miR-146a, miR-223, and miR-126. We used quantitative real-time PCRto evaluate the expression of these miRNAs on isolated BM mononuclear cells (BM-MNCs) from treated and untreated AA mice. miR-223, miR-146a, and miR-199a expressions increased in the MSC-EVs treated AA mice. Treatment with MSC-EVs increased expression of miR-223 and miR-146a. Our findings showed that treatment with MSC-EVs significantly ameliorated immune destruction of HSCsin the AA mouse model and confirmed the importance of miRNAs in the clinical status of this model.

Sphingosine 1-Phosphate Receptor Modulator ONO-4641 Regulates Trafficking of T Lymphocytes and Hematopoietic Stem Cells and Alleviates Immune-Mediated Aplastic Anemia in a Mouse Model.

ONO-4641 is a second-generation sphingosine 1-phosphate (S1P) receptor modulator that exhibits selectivity for S1P receptors 1 and 5. Treatment with ONO-4641 leads to a reduction in magnetic resonance imaging disease measures in patients with relapsing-remitting multiple sclerosis. The objective of this study was to explore the potential impact of ONO-4641 treatment based on its immunomodulatory effects. Severe aplastic anemia is a bone marrow (BM) failure disease typically caused by aberrant immune destruction of blood progenitors. Although the T helper type 1-mediated pathology is well described for aplastic anemia, the molecular mechanisms driving disease progression remain undefined. We evaluated the efficacy of ONO-4641 in a mouse model of aplastic anemia. ONO-4641 reduced the severity of BM failure in a dose-dependent manner, resulting in higher blood and BM cell counts. By evaluating the mode of action, we found that ONO-4641 inhibited the infiltration of donor-derived T lymphocytes to the BM. ONO-4641 also induced the accumulation of hematopoietic stem cells in the BM of model mice. These observations indicate, for the first time, that S1P receptor modulators demonstrate efficacy in the mouse model of aplastic anemia and suggest that treatment with ONO-4641 might delay the progression of aplastic anemia. SIGNIFICANCE STATEMENT: ONO-4641 is a second-generation sphingosine 1-phosphate (S1P) receptor modulator selective for S1P receptors 1 and 5. In this study, we demonstrated that ONO-4641 regulates the trafficking of T lymphocytes along with hematopoietic stem and progenitor cells, leading to alleviation of pancytopenia and destruction of bone marrow in a bone marrow failure-induced mouse model mimicking human aplastic anemia.