Feifei Yang

Diverse in vivo effects of soluble and membrane-bound M-CSF on tumor-associated macrophages in lymphoma xenograft model

Macrophage colony-stimulating factor (M-CSF) is an important cytokine for monocyte/macrophage lineage. Secretory M-CSF (sM-CSF) and membrane-bound M-CSF (mM-CSF) are two major alternative splicing isoforms. The functional diversity of these isoforms in the activation of tumor-associated macrophages (TAMs), especially in lymphoma microenvironment, has not been documented. Here, we studied the effects of M-CSF isoforms on TAMs in xenograft mouse model. More infiltrating TAMs were detected in microenvironment with mM-CSF and sM-CSF. TAMs could be divided into three subpopulations based on their expression of CD206 and Ly6C. While sM-CSF had greater potential to recruit and induce differentiation of TAMs and TAM subpopulations, mM-CSF had greater potential to induce proliferation of TAMs and TAM subpopulations. Though both isoforms educated TAMs and TAM subpopulations to M2-like macrophages, mM-CSF and sM-CSF induced different spectrums of phenotype-associated genes in TAMs and TAM subpopulations. These results suggested the diverse effects of M-CSF isoforms on the activation of TAMs and TAM subpopulations in lymphoma microenvironments.

Hepatic leukemia-associated macrophages exhibit a pro-inflammatory phenotype in Notch1-induced acute T cell leukemia

Tumor-associated macrophages (TAMs) are well accepted and the pathological role of macrophages in hematopoietic malignancies have been proposed. Hepatomegaly is frequently observed in T cell acute lymphoblastic leukemia (T-ALL) patients with poor prognosis. However, the role of leukemia-associated macrophages (LAMs) in hepatic microenvironment remains unclear. Here, the characteristics of hepatic LAMs (H-LAMs) were studied in Notch1 induced T-ALL model. Increase in proportion and absolute counts of H-LAMs was detected with infiltration of inflammatory cells. Furthermore, H-LAMs exhibited a more M1-like phenotype distinct from that of TAMs in hepatocellular carcinoma and LAMs from BM or spleen in leukemia. Moreover, H-LAMs expressed increased level of cytokines in charge of recruiting inflammatory cells, which contributed to pro-inflammatory hepatic microenvironment.

Characterization of peritoneal leukemia-associated macrophages in Notch1-induced mouse T cell acute lymphoblastic leukemia

HighlightsPer macrophages and Per LAMs simultaneously expressed high level iNOS and Arg1, which was not commonly observed in macrophages from other origins.LAMs from peritoneal, BM and spleen expressed lower level CSF‐1, TGF‐&bgr;1 and VEGF‐A than tumor‐associated macrophages (TAMs).Diverse responses in the expression of some phenotype‐associated genes to leukemia microenvironments were detected among those LAMs.Per LAMs can be sub‐divided into CD206+ and CD206− sub‐populations, which expressed both M1‐ and M2‐associated genes. ABSTRACT Macrophages, which have remarkable plasticity, are indispensable cellular components and play essential roles in both innate and adaptive immune responses. Peritoneal macrophages show unique gene expression profile and peritoneal cavity is also involved in leukemia. However, the characteristics of peritoneal leukemia‐associated macrophages (Per LAMs) have not been established. Here we studied the phenotype of Per LAMs, their subpopulations in Notch1‐induced acute lymphoblastic leukemia mice and compared with LAMs from BM or spleen in the same model. Peritoneal macrophages and Per LAMs simultaneously expressed high level iNOS and Arg1, which was not commonly observed in macrophages from different origins. Furthermore, LAMs from peritoneal, BM and spleen expressed lower level CSF‐1, TGF‐&bgr;1 and VEGF‐A than tumor‐associated macrophages (TAMs). Moreover, diverse responses in the expression of some phenotype‐associated genes to leukemia microenvironments were detected among those LAMs. In addition, Per LAMs can be sub‐divided into CD206+ and CD206− sub‐populations, which expressed both M1‐ and M2‐associated genes. These results revealed the unique phenotype of Per macrophages and Per LAMs and contributed to better understanding of macrophage plasticity and their pathological roles in leukemia.

High Level P2X7-Mediated Signaling Impairs Function of Hematopoietic Stem/Progenitor Cells

Nucleotides, which bind to P2 receptors, have emerged as a family of mediators in intercellular communication. P2X7 is a member of the P2X family ligand-gated ion channels respond to extracellular ATP. High level expression of P2X7 was detected in leukemia samples, especially in relapsed cases. However, the role of P2X7 mediated signaling in hematopoietic stem/progenitor cells (HSPCs) as well as its potential role in leukemogenesis have not been established. In this study, the expression of P2X7 in hematopoietic cells in different lineages and stages was analyzed. Over-expression of P2X7 in HSPCs was carried out by retrovirus infection to study the impact on HSPCs. The results showed that low level expression of P2X7 was detected in HSPCs. Over-expression of P2X7 in HSPCs resulted in decreased colony forming ability in vitro and engraftment potential in vivo. These results suggested that high level purinergic signaling by P2X7 impaired function of HSPCs.

Characteristics of NK cells from leukemic microenvironment in MLL-AF9 induced acute myeloid leukemia.

Graphical abstract Figure. No Caption available. HighlightsSplenic AML microenvironment promoted the accumulation of more mature NK cells.Splenic AML microenvironment promoted NK cell activation in early/middle stages.Cytotoxicity molecules and cytokines were up‐regulated in activated NK cells.AML affected gene expression profiles of NK subsets marked by DNAM‐1.Both AML‐modified NK cells and NK subsets regulated T cell adaptive immune. Abstract NK cells are indispensable components of tissue microenvironment and play vital in both innate and adaptive immunity. The activation and function of NK cells are affected by tumor microenvironments. NK cells are also important players in leukemic microenvironment. However, their characteristics in leukemic microenvironment, including maturation status, phenotype, subpopulations and functional roles especially immunoregulatory potential, have not been well established. Here, we studied these characteristics of NK cells in MLL‐AF9 induced mouse acute myeloid leukemia (AML) model. Increase of more mature NK cells were detected in the AML spleen. Splenic AML microenvironment promoted NK cell activation in early and middle stages of leukemia. Cytotoxicity molecules and cytokines were up‐regulated in activated NK cells. Furthermore, NK cells from AML microenvironment regulated T cell function, not only by maintaining the activation of CD4+ and promoting the degranulation of cytotoxic CD8+ T cells but also by influencing the differentiation of CD4+ T cells. Moreover, two NK cell subpopulations marked by DNAM‐1 (CD226) had distinct cytokine expression patterns but similar regulatory effects on T cells. Collectively, these findings highlight the significance of immunoregulatory role of NK cells, and suggest novel therapeutic potential for leukemia by manipulating NK cell immunoregulatory activity.

Heterogeneous effects of M-CSF isoforms on the progression of MLL-AF9 leukemia

Macrophage colony‐stimulating factor (M‐CSF) regulates both malignant cells and microenvironmental cells. Its splicing isoforms show functional heterogeneity. However, their roles on leukemia have not been well established. Here, the expression of total M‐CSF in patients with hematopoietic malignancies was analyzed. The roles of M‐CSF isoforms on the progression of acute myeloid leukemia (AML) were studied by establishing MLL‐AF9‐induced mouse AML models with high level membrane‐bound M‐CSF (mM‐CSF) or soluble M‐CSF (sM‐CSF). Total M‐CSF was highly expressed in myeloid leukemia patients. Furthermore, mM‐CSF but not sM‐CSF prolonged the survival of leukemia mice. While sM‐CSF was more potent to promote proliferation and self‐renew, mM‐CSF was more potent to promote differentiation. Moreover, isoforms had different effects on leukemia‐associated macrophages (LAMs) though they both increase monocytes/macrophages by growth‐promoting and recruitment effects. In addition, mM‐CSF promoted specific phagocytosis of leukemia cells by LAMs. RNA‐seq analysis revealed that mM‐CSF enhanced phagocytosis‐associated genes and activated oxidative phosphorylation and metabolism pathway. These results highlight heterogeneous effects of M‐CSF isoforms on AML progression and the mechanisms of mM‐CSF, that is, intrinsically promoting AML cell differentiation and extrinsically enhancing infiltration of macrophages and phagocytosis by macrophages, which may provide potential clues for clinical diagnosis and therapy.

Fbxw11 promotes the proliferation of lymphocytic leukemia cells through the concomitant activation of NF-κB and β-catenin/TCF signaling pathways

The ubiquitin–proteasome system (UPS) participates in both physiological and pathological processes through the posttranslational regulation of intracellular signal transduction pathways. F-box and WD-40 domain protein 11 (Fbxw11) is a component of the SCF (Skp1–Cul1–F-box) E3 ubiquitin ligase complex. Fbxw11 regulates various signal transduction pathways, and it may have pathological roles in tumorigenesis. However, the role of Fbxw11 in the development of leukemia and the underlying mechanisms remain largely unknown. In this study, Fbxw11 expression was aberrantly upregulated in patients with lymphocytic leukemia. Its expression was dramatically decreased in patients who achieved complete remission (CR) after chemotherapy. The high level of Fbxw11 expression in L1210 lymphocytic leukemia cells stimulated cell proliferation in vitro and tumor formation in vivo. The effects were mediated by the stimulation of cell cycle progression rather than the induction of apoptosis. Furthermore, a bioinformatics analysis suggested concomitant activation of the NF-κB and β-catenin/TCF signaling pathways, which were confirmed by reporter gene assays. Moreover, blocking experiments suggested the involvement of both pathways in the growth-promoting effects of Fbxw11. Our results reveal the role of Fbxw11 in lymphocytic leukemia cells and imply that Fbxw11 may serve as a potential molecular target for the treatment of lymphocytic leukemia.

Repolarizing heterogeneous leukemia-associated macrophages with more M1 characteristics eliminates their pro-leukemic effects

ABSTRACT Macrophages exhibit phenotypic heterogeneity under both physiological and pathological conditions. Applications targeting M2-like tumor-associated macrophages (TAMs) improve outcome in solid tumors. Considerable differences are detected between leukemia-associated macrophages (LAMs) and TAMs. However, application to induce M1 characteristics in heterogeneous LAMs has not been established. Here we analyzed clinical relevance of macrophage phenotypes in human acute myeloid leukemia (AML), studied phenotypic evolution of bone marrow (BM) and spleen (SP) LAMs in mouse AML and T cell acute lymphoblastic leukemia (T-ALL) models, explored mechanism leading to different LAM phenotypes and tried to eliminate pro-leukemic effects by inducing M1 characteristics. The results showed that more M2-like LAMs but not total LAMs correlated with worse prognosis in AML patients. Heterogeneity of LAM activation in tissue-specific leukemic microenvironments was observed in both AML and ALL models, i.e. SP LAMs evolved with more M2 characteristics while BM LAMs with more M1 characteristics. Furthermore, IRF7 contributed to M1 characteristics through the activation of SAPK/JNK pathway. Moreover, targeting IRF7-SAPK/JNK pathway to induce M1 characteristics in LAMs contributed to prolonged survival in leukemia mice. Our study provides the potential target for macrophage based immuno-therapy strategy against leukemia.