title: Tissue-resident versus monocyte-derived macrophages in the tumor microenvironment.
abstract: The tumor-promoting role of macrophages has been firmly established in most cancer types. However, macrophage identity has been a matter of debate, since several levels of complexity result in considerable macrophage heterogeneity. Ontogenically, tissue-resident macrophages derive from yolk sac progenitors which either directly or via a fetal liver monocyte intermediate differentiate into distinct macrophage types during embryogenesis and are maintained throughout life, while a disruption of the steady state mobilizes monocytes and instructs the formation of monocyte-derived macrophages. Histologically, the macrophage phenotype is heavily influenced by the tissue microenvironment resulting in molecularly and functionally distinct macrophages in distinct organs. Finally, a change in the tissue microenvironment as a result of infectious or sterile inflammation instructs different modes of macrophage activation. These considerations are relevant in the context of tumors, which can be considered as sites of chronic sterile inflammation encompassing subregions with distinct environmental conditions (for example, hypoxic versus normoxic). Here, we discuss existing evidence on the role of macrophage subpopulations in steady state tissue and primary tumors of the breast, lung, pancreas, brain and liver.
authors.affiliation: Myeloid Cell Immunology Lab, VIB, Brussels, Belgium; Lab of Cellular and Molecular Immunology, Vrije Universiteit Brussel, Brussels, Belgium.
authors.forename: Qods
authors.initials: Q
authors.lastname: Lahmar
authors.affiliation: Myeloid Cell Immunology Lab, VIB, Brussels, Belgium; Lab of Cellular and Molecular Immunology, Vrije Universiteit Brussel, Brussels, Belgium.
authors.forename: Jiri
authors.initials: J
authors.lastname: Keirsse
authors.affiliation: Myeloid Cell Immunology Lab, VIB, Brussels, Belgium; Lab of Cellular and Molecular Immunology, Vrije Universiteit Brussel, Brussels, Belgium.
authors.forename: Damya
authors.initials: D
authors.lastname: Laoui
authors.affiliation: Myeloid Cell Immunology Lab, VIB, Brussels, Belgium; Lab of Cellular and Molecular Immunology, Vrije Universiteit Brussel, Brussels, Belgium.
authors.forename: Kiavash
authors.initials: K
authors.lastname: Movahedi
authors.affiliation: Myeloid Cell Immunology Lab, VIB, Brussels, Belgium; Lab of Cellular and Molecular Immunology, Vrije Universiteit Brussel, Brussels, Belgium.
authors.forename: Eva
authors.initials: E
authors.lastname: Van Overmeire
authors.affiliation: Myeloid Cell Immunology Lab, VIB, Brussels, Belgium; Lab of Cellular and Molecular Immunology, Vrije Universiteit Brussel, Brussels, Belgium. Electronic address: jvangind@vub.ac.be.
authors.forename: Jo A
authors.initials: JA
authors.lastname: Van Ginderachter
mesh_terms: D000818:Animals; D006801:Humans; D008264:Macrophages / Q000502:physiology*; D009000:Monocytes / Q000166:cytology*; D009369:Neoplasms / Q000276:immunology*; D059016:Tumor Microenvironment
keywords: Breast cancer; Glioma; Hepatocellular carcinoma; Kupffer cell; Lung cancer; Microglia; Monocyte-derived macrophages; Pancreatic adenocarcinoma; Tissue-resident macrophages; Tumor-associated macrophages