title: Macrophage polarization in pathology.
abstract: Macrophages are cells of the innate immunity constituting the mononuclear phagocyte system and endowed with remarkable different roles essential for defense mechanisms, development of tissues, and homeostasis. They derive from hematopoietic precursors and since the early steps of fetal life populate peripheral tissues, a process continuing throughout adult life. Although present essentially in every organ/tissue, macrophages are more abundant in the gastro-intestinal tract, liver, spleen, upper airways, and brain. They have phagocytic and bactericidal activity and produce inflammatory cytokines that are important to drive adaptive immune responses. Macrophage functions are settled in response to microenvironmental signals, which drive the acquisition of polarized programs, whose extremes are simplified in the M1 and M2 dichotomy. Functional skewing of monocyte/macrophage polarization occurs in physiological conditions (e.g., ontogenesis and pregnancy), as well as in pathology (allergic and chronic inflammation, tissue repair, infection, and cancer) and is now considered a key determinant of disease development and/or regression. Here, we will review evidence supporting a dynamic skewing of macrophage functions in disease, which may provide a basis for macrophage-centered therapeutic strategies.
authors.affiliation: Department of Pharmaceutical Sciences, Università del Piemonte Orientale "Amedeo Avogadro", via Bovio 6, Novara, Italy. antonio.sica@humanitasresearch.it.|Humanitas Clinical and Research Center, Via Manzoni 56, 20089, Milan, Rozzano, Italy. antonio.sica@humanitasresearch.it.
authors.forename: Antonio
authors.initials: A
authors.lastname: Sica
authors.affiliation: Humanitas Clinical and Research Center, Via Manzoni 56, 20089, Milan, Rozzano, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Erreni
authors.affiliation: Humanitas Clinical and Research Center, Via Manzoni 56, 20089, Milan, Rozzano, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Allavena
authors.affiliation: Department of Pharmaceutical Sciences, Università del Piemonte Orientale "Amedeo Avogadro", via Bovio 6, Novara, Italy.
authors.forename: Chiara
authors.initials: C
authors.lastname: Porta
mesh_terms: D016764:Cell Polarity; D015658:HIV Infections / Q000473:pathology; D016481:Helicobacter Infections / Q000473:pathology; D006706:Homeostasis; D006801:Humans; D006967:Hypersensitivity / Q000473:pathology; D007239:Infections / Q000382:microbiology / Q000469:parasitology / Q000473:pathology* / Q000821:virology; D008264:Macrophages / Q000473:pathology* / Q000502:physiology*; D009369:Neoplasms / Q000473:pathology*; D009765:Obesity / Q000378:metabolism / Q000473:pathology*; D018805:Sepsis / Q000473:pathology; D014376:Tuberculosis / Q000473:pathology; D014945:Wound Healing
keywords: Disease; Inflammation; Macrophage polarization; Tissue damage; Tissue homeostasis