Homoharringtonine sensitized resistant acute myeloid leukemia cells to venetoclax-induced apoptosis.

Venetoclax (VEN), a B-cell lymphoma 2 (BCL-2) selective inhibitor, is widely used for treating acute myeloid leukemia (AML) with promising results. However, the anti-leukemic effect of VEN in relapsed/refractory (R/R)- AML requires improvement. In this study, we observed that combining homoharringtonine (HHT) with VEN plus azacitidine resulted in a significantly higher response and better survival than VA alone in patients with R/R-AML. Basic research indicates that HHT combined with VEN has a highly synergistic effect against both resistant AML cells and primary cells with/without mesenchymal stem cell (MSC) co-culture in vivo, inhibiting proliferation and colony-forming capacity of AML cells associated with concomitant cell cycle arrest. Mechanistically, HHT sensitizes AML cells to VEN by downregulating the anti-apoptotic proteins MCL-1/BCL-xL, activating reactive oxygen species (ROS), leading to mitochondrial membrane potential loss, and attenuating fatty acid (FA) uptake. These findings adding HHT to VEN-based regimens may enhance outcomes in R/R-AML patients.

Human Amniotic Membrane-Derived Mesenchymal Stem Cells Prevent Acute Graft-Versus-Host Disease in an Intestinal Microbiome-Dependent Manner.

Acute graft-versus-host disease (aGVHD) represents a fatal severe complication after allogeneic hematopoietic stem cell transplantation. As a promising cell therapeutic strategy of aGVHD, the mechanism of mesenchymal stem cells (MSC) to ameliorate aGVHD has not been fully clarified, especially in the field of intestinal homeostasis including the intestinal microbiome involved in the pathogenesis of aGVHD. The present study aimed to explore the effect of MSC on intestinal homeostasis including the intestinal barrier and intestinal microbiome and its metabolites, as well as the role of intestinal microbiome in the preventive process of hAMSCs ameliorating aGVHD. The preventive effects of human amniotic membrane-derived MSC (hAMSCs) was assessed in humanized aGVHD mouse models. Immunohistochemistry and RT-qPCR were used to evaluate intestinal barrier function. The 16S rRNA sequencing and targeted metabolomics assay were performed to observe the alternation of intestinal microbiome and the amounts of medium-chain fatty acids (MCFAs) and short-chain fatty acids (SCFAs), respectively. Flow cytometry was performed to analyze the frequencies of T immune cells. Through animal experiments, we found that hAMSCs had the potential to prevent aGVHD. HAMSCs could repair the damage of intestinal barrier structure and function, as well as improve the dysbiosis of intestinal microbiome induced by aGVHD, and meanwhile, upregulate the concentration of metabolites SCFAs, so as to reshape intestinal homeostasis. Gut microbiota depletion and fecal microbial transplantation confirmed the involvement of intestinal microbiome in the preventive process of hAMSCs on aGVHD. Our findings showed that hAMSCs prevented aGVHD in an intestinal microbiome-dependent manner, which might shed light on a new mechanism of hAMSCs inhibiting aGVHD and promote the development of new prophylaxis regimes for aGVHD prevention.

Therapeutic Effects of HLA-G5 Overexpressing hAMSCs on aGVHD After Allo-HSCT: Involving in the Gut Microbiota at the Intestinal Barrier.

Background: Acute graft-versus-host disease (aGVHD) initiated by intestinal barrier dysfunction and gut microbiota dysbiosis, remains one of the main obstacles for patients undergoing allogenic hematopoietic stem cell transplantation (allo-HSCT) to achieve good prognosis. Studies have suggested that mesenchymal stem cells (MSCs) can suppress immune responses and reduce inflammation, and human leukocyte antigen-G5 (HLA-G5) plays an important role in the immunomodulatory effects of MSCs, but very little is known about the potential mechanisms in aGVHD. Thus, we explored the effect of HLA-G5 on the immunosuppressive properties of human amnion MSCs (hAMSCs) and demonstrated its mechanism related to the gut microbiota at the intestinal barrier in aGVHD. Methods: Patients undergoing allo-HSCT were enrolled to detect the levels of plasma-soluble HLA-G (sHLA-G) and regulatory T cells (Tregs). Humanized aGVHD mouse models were established and treated with hAMSCs or HLA-G5 overexpressing hAMSCs (ov-HLA-G5-hAMSCs) to explore the mechanism of HLA-G5 mediated immunosuppressive properties of hAMSCs and the effect of ov-HLA-G5-hAMSCs on the gut microbiota at the intestinal barrier in aGVHD. Results: The plasma levels of sHLA-G on day +30 after allo-HSCT in aGVHD patients were lower than those in patients without aGVHD, and the sHLA-G levels were positively correlated with Tregs percentages. ov-HLA-G5-hAMSCs had the potential to inhibit the expansion of CD3+CD4+ T and CD3+CD8+ T cells and promote Tregs differentiation, suppress proinflammatory cytokine secretion but promote anti-inflammatory cytokines release. Besides, ov-HLA-G5-hAMSCs also could reverse the intestinal barrier dysfunction and gut microbiota dysbiosis in aGVHD. Conclusion: We demonstrated that HLA-G might work with Tregs to create a regulatory network together to reduce the occurrence of aGVHD. HLA-G5 mediated hAMSCs to exert higher immunosuppressive properties in vivo and reverse the immune imbalance caused by T lymphocytes and cytokines. Furthermore, HLA-G5 overexpressing hAMSCs could restore gut microbiota and intestinal barriers, thereby ameliorating aGVHD.

Human Amniotic Mesenchymal Stem Cells Alleviate aGVHD after allo-HSCT by Regulating Interactions between Gut Microbiota and Intestinal Immunity.

Acute graft-versus-host disease (aGVHD) after allogeneic hematopoietic stem cell transplantation poses one of the most vexing challenges. Gut microbiota dysbiosis can proceed aGVHD and mesenchymal stem cells (MSCs) have promising therapeutic potential for aGVHD. However, whether hAMSCs affect the gut microbiota during aGVHD mitigation remains unknown. Accordingly, we sought to define the effects and underlying mechanisms of human amniotic membrane-derived MSCs (hAMSCs) regulating the gut microbiota and intestinal immunity in aGVHD. By establishing humanized aGVHD mouse models and hAMSCs treatment, we found that hAMSCs significantly ameliorated aGVHD symptoms, reversed the immune imbalance of T cell subsets and cytokines, and restored intestinal barrier. Moreover, the diversity and composition of gut microbiota were improved upon treatment with hAMSCs. Spearman's correlation analysis showed that there was a correlation between the gut microbiota and tight junction proteins, immune cells as well as cytokines. Our research suggested that hAMSCs alleviated aGVHD by promoting gut microbiota normalization and regulating the interactions between the gut microbiota and intestinal barrier, immunity.

Establishment of Prognosis Model in Acute Myeloid Leukemia Based on Hypoxia Microenvironment, and Exploration of Hypoxia-Related Mechanisms.

Acute myeloid leukemia (AML) is a highly heterogeneous hematologic neoplasm with poor survival outcomes. However, the routine clinical features are not sufficient to accurately predict the prognosis of AML. The expression of hypoxia-related genes was associated with survival outcomes of a variety of hematologic and lymphoid neoplasms. We established an 18-gene signature-based hypoxia-related prognosis model (HPM) and a complex model that consisted of the HPM and clinical risk factors using machine learning methods. Both two models were able to effectively predict the survival of AML patients, which might contribute to improving risk classification. Differentially expressed genes analysis, Gene Ontology (GO) categories, and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis were performed to reveal the underlying functions and pathways implicated in AML development. To explore hypoxia-related changes in the bone marrow immune microenvironment, we used CIBERSORT to calculate and compare the proportion of 22 immune cells between the two groups with high and low hypoxia-risk scores. Enrichment analysis and immune cell composition analysis indicated that the biological processes and molecular functions of drug metabolism, angiogenesis, and immune cell infiltration of bone marrow play a role in the occurrence and development of AML, which might help us to evaluate several hypoxia-related metabolic and immune targets for AML therapy.

Human Amniotic Mesenchymal Stem Cells Inhibit aGVHD by Regulating Balance of Treg and T Effector Cells.

BACKGROUND: Acute graft versus host disease (aGVHD) remains a leading cause of transplant-related mortality following allogeneic haematopoietic cell transplantation (allo-HCT). Human amniotic mesenchymal stem cells (hAMSCs) are a novel mesenchymal stem cells (MSCs), which have stronger proliferation and immunomodulatory ability compared with bone marrow mesenchymal stem cells (BM-MSCs). Besides, as the amniotic membrane is often treated as medical waste after delivery, hAMSCs can be obtained conveniently and noninvasively. The aim of this study was to explore the therapeutic efficacy and underlying mechanisms of hAMSCs transplantation for the humanized aGVHD mouse model. METHODS: We established a humanized aGVHD mouse model by transplanting human peripheral blood mononuclear cells (PBMCs) into NOD-PrkdcscidIL2rγnull (NPG) mice, human amniotic membrane collected from discarded placenta of healthy pregnant women after delivery and hAMSCs were extracted from amniotic membrane and expanded in vitro. Mice were divided into untreated group (Control), aGVHD group (aGVHD), and hAMSCs treatment group (aGVHD+hAMSCs), the hAMSCs labeled with GFP were administered to aGVHD mice to explore the homing ability of hAMSCs. T effector and regulatory T cells (Tregs) levels and cytokines of each group in target organs were detected by flow cytometry and cytometric bead array (CBA), respectively. RESULTS: We successfully established a humanized aGVHD mouse model using NPG mice. The hAMSCs have the ability to inhibit aGVHD in this mouse model through reduced villous blunting and lymphocyte infiltration of the gut while reducing inflammatory edema, tissue destruction and lymphocyte infiltration into the parenchyma of the liver and lung. hAMSCs suppressed CD3+CD4+ T and CD3+CD8+ T cell expression and increased the proportion of Tregs, and besides, hAMSCs can reduce the levels of IL-17A, INF-γ, and TNF in aGVHD target organs. CONCLUSION: The NPG murine environment was capable of activating human T cells to produce aGVHD pathology to mimic aGVHD as in humans. The hAMSCs controlled aGVHD by decreasing inflammatory cytokine secretion within target organs by modulating the balance of Tregs and T effector cells in humanized mice.

Immunomodulating functions of human leukocyte antigen-G and its role in graft-versus-host disease after allogeneic hematopoietic stem cell transplantation.

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a potentially curative therapeutic strategy to treat several hematological malignancies and non-hematological malignancies. However, graft-versus-host disease (GVHD) is a frequent and serious transplant-related complication which dramatically restrains the curative effect of allo-HSCT and a significant cause of morbidity and mortality in allogeneic HCT recipients. Effective prevention of GVHD mainly depends on the induction of peripheral immune tolerance. Human leukocyte antigen-G (HLA-G) is a non-classical MHC class I molecule with a strong immunosuppressive function, which plays a prominent role in immune tolerance. HLA-G triggers different reactions depending on the activation state of the immune cells and system. It also exerts a long-term immune tolerance mechanism by inducing regulatory cells. In this present review, we demonstrate the immunomodulatory properties of human leukocyte antigen-G and highlight the role of HLA-G as an immune regulator of GVHD. Furthermore, HLA-G could also serve as a good predictor of GVHD and represent a new therapeutic target for GVHD.