Myeloid Cell Immunology Laboratory

Brussels, Belgium

Myeloid Cell Immunology Laboratory

Brussels, Belgium
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de Veirman K.,Vrije Universiteit Brussel | van Ginderachter J.A.,Vrije Universiteit Brussel | van Ginderachter J.A.,Myeloid Cell Immunology Laboratory | Lub S.,Vrije Universiteit Brussel | And 10 more authors.
Oncotarget | Year: 2015

Myeloid-derived suppressor cells (MDSC) are contributing to an immunosuppressive environment by their ability to inhibit T cell activity and thereby promoting cancer progression. An important feature of the incurable plasma cell malignancy Multiple Myeloma (MM) is immune dysfunction. MDSC were previously identified to be present and active in MM patients, however little is known about the MDSC-inducing and-activating capacity of MM cells. In this study we investigated the effects of the tumor microenvironment on MDSC survival. During MM progression in the 5TMM mouse model, accumulation of MDSC in the bone marrow was observed in early stages of disease development, while circulating myeloid cells were increased at later stages of disease. Interestingly, in vivo MDSC targeting by anti-GR1 antibodies and 5-Fluorouracil resulted in a significant reduced tumor load in 5TMM-diseased mice. In vitro generation of MDSC was demonstrated by increased T cell immunosuppressive capacity and MDSC survival was observed in the presence of MM-conditioned medium. Finally, increased Mcl-1 expression was identified as underlying mechanism for MDSC survival. In conclusion, our data demonstrate that soluble factors from MM cells are able to generate MDSC through Mcl-1 upregulation and this cell population can be considered as a possible target in MM disease.


van den Bossche J.,Myeloid Cell Immunology Laboratory | Lamers W.H.,Vrije Universiteit Brussel | Koehler E.S.,Vrije Universiteit Brussel | Geuns J.M.C.,Maastricht University | And 10 more authors.
Journal of Leukocyte Biology | Year: 2012

In macrophages, basal polyamine (putrescine, spermidine, and spermine) levels are relatively low but are increased upon IL-4 stimulation. This Th2 cytokine induces Arg1 activity, which converts arginine into ornithine, and ornithine can be decarboxylated by ODC to produce putrescine, which is further converted into spermidine and spermine. Recently, we proposed polyamines as novel agents in IL-4-dependent E-cadherin regulation in AAMs. Here, we demonstrate for the first time that several, but not all, AAM markers depend on polyamines for their IL-4-induced gene and protein expression and that polyamine dependency of genes relies on the macrophage type. Remarkably, Arg1-deficient macrophages display rather enhanced IL-4-induced polyamine production, suggesting that an Arg1-independent polyamine synthesis pathway may operate in macrophages. On the other side of the macrophage activation spectrum, LPS-induced expression of several proinflammatory genes was increased significantly in polyamine-depleted CAMs. Overall, we propose Arg1 independently produced polyamines as novel regulators of the inflammatory status of the macrophage. Indeed, whereas polyamines are needed for IL-4-induced expression of several AAM mediators, they inhibit the LPS-mediated expression of proinflammatory genes in CAMs. © Society for Leukocyte Biology.


Beschin A.,Myeloid Cell Immunology Laboratory | Beschin A.,Vrije Universiteit Brussel | Van Den Abbeele J.,Antwerp Institute of Tropical Medicine | Van Den Abbeele J.,Ghent University | And 3 more authors.
Trends in Parasitology | Year: 2014

The life cycle of African trypanosomes involves adaptations to the defense mechanisms of two completely different hosts, the insect vector Glossina and the mammalian host. This interplay ultimately determines host resistance and/or tolerance to parasite infection. In the tsetse fly, the immune deficiency (IMD)-regulated pathway, the scavenger receptor peptidoglycan-recognition protein LB (PGRP-LB), and the reactive oxygen species (ROS)-mediated response modulate the insect's capacity to transmit the parasite. In experimental mice, control of parasite burden and tissue pathogenicity relies on timely regulated interactions between myeloid cells exhibiting distinct activation states (M1 versus M2 type). Tsetse fly saliva and various trypanosome components including adenylate cyclases, DNA, a kinesin heavy chain, and variant surface glycoprotein (VSG) interfere with resistance and tolerance to infection. © 2014 Elsevier Ltd.


Tran H.T.T.,Vrije Universiteit Brussel | Tran H.T.T.,Myeloid Cell Immunology Laboratory | Van Den Bergh R.,Vrije Universiteit Brussel | Van Den Bergh R.,Myeloid Cell Immunology Laboratory | And 13 more authors.
AIDS | Year: 2013

OBJECTIVE: Tuberculosis-associated immune reconstitution inflammatory syndrome (TB-IRIS) is a common complication in HIV-TB co-infected patients receiving combined antiretroviral therapy (cART). This study investigated a putative contribution of monocytes to the development of TB-IRIS. DESIGN: A prospective study was designed to compare gene expression between patients who developed TB-IRIS with matched non-TB-IRIS controls. METHODS: We performed a hypothesis-generating transcriptome analysis on monocytes of HIV-TB co-infected patients. Identified pathways were subsequently analysed in patients' monocytes before and shortly after cART initiation, in a technically independent set-up (nCounter). Additionally, protein expression and enzymatic activities of specific factors were assessed at the systemic level. RESULTS: Pathway analysis of microarray datasets and focused gene expression study revealed that, even before initiation of cART, the complement system is dysregulated in HIV-TB co-infected patients who are predisposed to developing TB-IRIS. Detailed analysis revealed differences between TB-IRIS patients and matched non-TB-IRIS cases, at the level of the balance between the effector C1Q and the inhibitor C1-INH, both before and 2 weeks after cART initiation. These differences were mirrored by increases in the downstream pro-inflammatory complement factor C5 over the course of 2 weeks of cART. Our results suggest that inappropriate control of complement activation could be associated with the 'flaring up' of inflammation observed during TB-IRIS. CONCLUSION: The current study reveals a contribution of monocytes and the complement system to TB-IRIS development. An intriguing possibility is that the development of TB-IRIS may depend partially on the relative balance between C1Q and C1-INH. © 2013 Creative Common License.


Van Overmeire E.,Myeloid Cell Immunology Laboratory | Van Overmeire E.,Vrije Universiteit Brussel | Laoui D.,Myeloid Cell Immunology Laboratory | Laoui D.,Vrije Universiteit Brussel | And 7 more authors.
Frontiers in Immunology | Year: 2014

Macrophages are extremely versatile cells that adopt a distinct phenotype in response to a changing microenvironment. Consequently, macrophages are involved in diverse functions, ranging from organogenesis and tissue homeostasis to recognition and destruction of invading pathogens. In cancer, tumor-associated macrophages (TAM) often contribute to tumor progression by increasing cancer cell migration and invasiveness, stimulating angiogenesis, and suppressing anti-tumor immunity. Accumulating evidence suggests that these different functions could be exerted by specialized TAM subpopulations. Here, we discuss the potential underlying mechanisms regulating TAM specialization and elaborate on TAM heterogeneity in terms of their ontogeny, activation state, and intra-tumoral localization. In addition, parallels are drawn between TAM and macrophages in other tissues. Together, a better understanding of TAM diversity could provide a rationale for novel strategies aimed at targeting the most potent tumor-supporting macrophages. © 2014 Van Overmeire, Laoui, Keirsse, Van Ginderachter and Sarukhan.


Korf H.,Catholic University of Leuven | Wenes M.,Catholic University of Leuven | Stijlemans B.,Vrije Universiteit Brussel | Stijlemans B.,Myeloid Cell Immunology Laboratory | And 6 more authors.
Immunobiology | Year: 2012

The vitamin D receptor (VDR) is a hormone nuclear receptor regulating bone and calcium homeostasis. Studies revealing the expression of VDR on immune cells point toward a role for VDR-dependent signaling pathways in immunity. Here we verified the ability of the natural VDR ligand, 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) to interfere in inflammatory and T cell stimulatory capacity of macrophages, in particular within a chronic inflammatory disease features of experimental type 1 diabetes (T1D). We demonstrated that VDR is constitutively expressed in macrophages and both the levels of VDR and its downstream targets, are clearly induced by 1,25(OH)2D3. In control mice, macrophage programming with 1,25(OH)2D3 partially abrogated the activation-provoked expression of IL-12p40, TNFα and iNOS as well as the effector T cell-recruiting chemokines, CXCL9, CXCL10 and CXCL11. Targeting VDR signaling in macrophages counteracted their T-cell stimulatory ability despite essentially unaltered expression of antigen-presenting and costimulatory molecules. Furthermore, even in non-obese diabetic (NOD) mice, where macrophages/monocytes featured a heightened responsiveness toward danger signals and a superior T cell stimulatory capacity, 1,25(OH)2D3 successfully curtailed these basic macrophage-mediated functions. Interestingly, the inhibitory action of the active compound was associated with an IL-10-dependent mechanism since 1,25(OH)2D3-treatment of IL-10-deficient macrophages failed to reproduce the characteristic repression on inflammatory mediators or T cell proliferation. Combined, these results highlight the possible therapeutic applicability of this natural immunomodulator, due to its ability to counteract macrophage inflammatory and T cell-activating pathways. © 2012 Elsevier GmbH.


Overmeire E.V.,Vrije Universiteit Brussel | Overmeire E.V.,Myeloid Cell Immunology Laboratory | Laoui D.,Vrije Universiteit Brussel | Laoui D.,Myeloid Cell Immunology Laboratory | And 4 more authors.
OncoImmunology | Year: 2014

Tumor-associated macrophages (TAMs) provide a significant contribution to tumor growth and metastasis. We demonstrated the existence of two main TAM subsets, differing in activation state and localization. Of these, M2-like TAMs reside in hypoxic regions of the tumor mass and can be used as targets for hypoxia tracers. This said, hypoxia does not regulate the differentiation of TAMs but finely tunes the activity of the M2-like population. © 2014 Landes Bioscience.


Beschin A.,Myeloid Cell Immunology Laboratory | Beschin A.,Vrije Universiteit Brussel | De Baetselier P.,Myeloid Cell Immunology Laboratory | De Baetselier P.,Vrije Universiteit Brussel | And 2 more authors.
Journal of Pathology | Year: 2013

Accumulation of extracellular matrix components secreted by fibroblasts is a normal feature of wound healing during acute inflammation. However, during most chronic/persistent inflammatory diseases, this tissue repair mechanism is incorrectly regulated and results in irreversible fibrosis in various organs. Fibrosis that severely affects tissue architecture and can cause organ failure is a major cause of death in developed countries. Organ-recruited lymphoid (mainly T cells) and myeloid cells (eosinophils, basophils, macrophages and DCs) have long been recognized in their participation to the development of fibrosis. In particular, a central role for recruited monocyte-derived macrophages in this excessive connective tissue deposit is more and more appreciated. Moreover, the polarization of monocyte-derived macrophages in classically activated (IFNγ-dependent) M1 cells or alternatively activated (IL-4/IL-13) M2 cells, that mirrors the Th1/Th2 polarization of T cells, is also documented to contribute differentially to the fibrotic process. Here, we review the current understanding of how myeloid cell subpopulations affect the development of fibrosis in parasite infections. Copyright © 2012 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. Copyright © 2012 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.


Laoui D.,Myeloid Cell Immunology Laboratory | Laoui D.,Vrije Universiteit Brussel | van Overmeire E.,Myeloid Cell Immunology Laboratory | van Overmeire E.,Vrije Universiteit Brussel | And 6 more authors.
Frontiers in Immunology | Year: 2014

The current review article describes the functional relationship between tumor-associated macrophages (TAM) as key cellular contributors to cancer malignancy on the one hand and macrophage-colony-stimulating factor (M-CSF or CSF-1) as an important molecular contributor on the other. We recapitulate the available data on expression of M-CSF and the M-CSF receptor (M-CSFR) in human tumor tissue as constituents of a stromal macrophage signature and on the limits of the predictive and prognostic value of plasma M-CSF levels. After providing an update on current insights into the nature of TAM heterogeneity at the level of M1/M2 phenotype and TAM subsets, we give an overview of experimental evidence, based on genetic, antibody-mediated, and pharmacological disruption of M-CSF/M-CSFR signaling, for the extent to which M-CSFR signaling can not only determine the TAM quantity, but can also contribute to shaping the phenotype and heterogeneity of TAM and other related tumor-infiltrating myeloid cells (TIM). Finally, we review the accumulating information on the - sometimes conflicting - effects blocking M-CSFR signaling may have on various aspects of cancer progression such as tumor growth, invasion, angiogenesis, metastasis, and resistance to therapy and we thereby discuss in how far these different effects actually reflect a contribution of TAM. © 2014 Laoui, Van Overmeire, De Baetselier, Van Ginderachter and Raes.


Daniel B.,Debrecen University | Nagy G.,Debrecen University | Hah N.,Salk Institute for Biological Studies | Horvath A.,Debrecen University | And 13 more authors.
Genes and Development | Year: 2014

RXR signaling is predicted to have a major impact in macrophages, but neither the biological consequence nor the genomic basis of its ligand activation is known. Comprehensive genome-wide studies were carried out to map liganded RXR-mediated transcriptional changes, active binding sites, and cistromic interactions in the context of the macrophage genome architecture. The macrophage RXR cistrome has 5200 genomic binding sites, which are not impacted by ligand. Active enhancers are characterized by PU.1 binding, an increase of enhancer RNA, and P300 recruitment. Using these features, 387 liganded RXR-bound enhancers were linked to 226 genes, which predominantly reside in CTCF/cohesin-limited functional domains. These findings were molecularly validated using chromosome conformation capture (3C) and 3C combined with sequencing (3C-seq), and we show that selected long-range enhancers communicate with promoters via stable or RXR-induced loops and that some of the enhancers interact with each other, forming an interchromosomal network. A set of angiogenic genes, including Vegfa, has liganded RXR-controlled enhancers and provides the macrophage with a novel inducible program. © 2014 Daniel et al.

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