Chronic lymphocytic leukemia nurse-like cells express hepatocyte growth factor receptor (c-MET) and indoleamine 2,3-dioxygenase and display features of immunosuppressive type 2 skewed macrophages

Abstract

© F e r r a t a S t o r t i F o u n d a t i o nderived from co-culture of monocytes and autologous leukemic cells are characterized by a gene expression profile typical of cells with dysregulated immunocompetence which could be relevant in the context of the acquired immunodeficiency commonly found in CLL patients. 12Whether NLC represent CLL-specific tumor-associated macrophages, as recently suggested, 13 is still debated. We have recently reported that hepatocyte growth factor (HGF), together with CXCL12, is produced at high levels by stromal cells and is capable of prolonging the survival of CLL cells which are positive for the HGF receptor, c-MET.14 HGF is a multifunctional cytokine that induces multiple biological responses in target cells, including adhesion, motility, growth, survival and morphogenesis by activating its tyrosine kinase receptor, c-MET. 15,16 In normal individuals, HGF is constitutively produced by fibroblast-like stromal cells in lymphoid tissue and by follicular dendritic cells within the germinal center microenvironment. 15,17,18 NLC are present in the lymph nodes of CLL patients, where they are interspersed with stromal, dendritic and T cells to form proliferation centers. 19 The intriguing finding that HGF levels are higher in sera from CLL patients than from normal controls, 20 together with a still undefined pattern of effects induced by HGF on myelomonocytic cells, prompted us to determine c-MET expression on NLC and on monocytes-macrophages as well as investigate potential downstream events caused by the interaction between HGF and c-MET. MethodsThis study was approved by the review board of the IRCCS AOU San Martino -IST, Genoa, Italy. Full details are provided in the Online Supplementary Methods file. Cell preparationHeparinized blood or bone marrow samples were taken from CLL patients untreated for at least 3 months. The patients' characteristics are summarized in Online Supplementary Table S1. NLC were derived and characterized as described below and in the Online Supplementary Methods. CD14 + monocytes were purified from patients or healthy donors by magnetic beads. The human monocytic cell line THP-1 was utilized in selected experiments. Fluorescence microscopy and flow cytometryNLC or fresh monocytes from CLL or normal donors were challenged with antibodies against c-MET, indoleamine 2,3-dioxygenase (IDO), vimentin, CD68, interleukin (IL)-10, CD14, CXCR4, CD163 and pSTAT3 TYR705 and analyzed by immunofluorescence or flow cytometry. The quantification of pSTAT3 immunopositive cells area is described in detail in the Online Supplementary Methods. Analysis of STAT3 and pSTAT3 activation by western blottingWestern blotting was used to evaluate STAT3, pSTAT3 and bactin in monocytes from normal or CLL donors and in NLC with or without HGF treatment. Immunohistochemistry and immunofluorescence analysis of lymph node and bone marrow biopsiesTissue sections were probed with anti-human c-MET, -IDO, -vimentin, -CD68, and -CD163. 3,3'-Diaminobenzidine (DAB) substrate chromogen...

T-cell defect in diffuse large B-cell lymphomas involves expansion of myeloid-derived suppressor cells

“…25,37,38 Few studies were conducted on B-cell lymphomas or CLL, which focused exclusively on the M-MDSC subtype. [27][28][29]39 Because the majority of blood biomarkers in DLBCL are linked to tumor microenvironment and in particular to myeloid cell biology, 6,7,14-17 further characterization of the MDSC compartment is highly relevant in this disease. Our aim, in this study, was to characterize the various MDSC subsets in peripheral blood from DLBCL patients.…”

Lenalidomide interferes with tumor-promoting properties of nurse-like cells in chronic lymphocytic leukemia

“…33,44 It is well known that monocytes isolated from CLL patients have immunosuppressive properties characterized by a strong reduction in T-cell proliferation, and this anti-proliferative effect is caused, in part, by TGFβ, IDO1 and IL10. 5,7,21 We observed that lenalidomide is able to improve the ability of NLCs to stimulate T-cell proliferation. In line with these findings, a switch of NLCs properties to a pro-inflammatory profile was supported by gene expression profiling analysis.…”

“…45 The role of IDO1 in the immune response is still controversial, implying a possible involvement in M1 polarization or alternatively in immune tolerance. 7,46,47 Lenalidomide up-regulated IDO1 expression in NLCs. One possible explanation may account for the counter regulatory role of IDO1 to restrain excessive or inappropriate immune activation during an inflammatory response mediated by lenalidomide.…”

“…3,5,7 We then asked ourselves whether lenalidomide could interfere with the immunosuppressive profile of NLCs. In agreement with observations in monocytes, we found a strong stimulation of F-actin content in lenalidomide-treated NLCs ( Figure 5A).…”

“…[4][5][6] NLCs share several features with tumor-associated macrophages: secretion of IL10, IL8, but not IL12; high surface expression of CD11b, HLA-DR, CD163, CD206; and expression of indoleamine 2,3-dioxygenase (IDO). 3,5,7 Furthermore, NLCs also show deregulated expression of genes involved in immunocompetence. 8 NLCs protect leukemic cells from undergoing spontaneous or drug-induced apoptosis in a contact-dependent manner.…”