Macrophages in Tumor Microenvironments and the Progression of Tumors

• Published in: Clinical & developmental immunology Vol. 2012; no. 2012; pp. 1 - 11
• Main Authors: Lü, Mu-Han, Hao, Ning-Bo, Fan, Ya-Han, Cao, Ya-Ling, Zhang, Zhi-Ren, Yang, Shi-Ming
• Format: Journal Article
• Language: English
• Published: Cairo, Egypt Hindawi Puplishing Corporation 01.01.2012; Hindawi Publishing Corporation; Hindawi Limited; Wiley
• Subjects: Angiogenesis; Animals; Cancer; Chemokines; Cytotoxicity; Disease Progression; Drug resistance; Homeostasis; Humans; Immune response; Immune system; Immunology; Immunosuppression; Inflammation; Interleukin 10; Interleukin 12; Interleukin 23; Macrophages; Macrophages - immunology; Macrophages - metabolism; Metastases; Microenvironments; Neoplasms - immunology; Neoplasms - pathology; Neoplasms - therapy; Nitric-oxide synthase; Pathogens; Proteinase; Proteins; Review; Rodents; Stem cells; Studies; Transforming growth factor- beta; Tumor Microenvironment - immunology; Tumor necrosis factor- alpha; Tumorigenesis; Tumors; Wound healing
• ISSN: 1740-2522; 2314-8861; 1740-2530; 2314-7156
• DOI: 10.1155/2012/948098

Macrophages are widely distributed innate immune cells that play indispensable roles in the innate and adaptive immune response to pathogens and in-tissue homeostasis. Macrophages can be activated by a variety of stimuli and polarized to functionally different phenotypes. Two distinct subsets of macrophages have been proposed, including classically activated (M1) and alternatively activated (M2) macrophages. M1 macrophages express a series of proinflammatory cytokines, chemokines, and effector molecules, such as IL-12, IL-23, TNF-α, iNOS and MHCI/II. In contrast, M2 macrophages express a wide array of anti-inflammatory molecules, such as IL-10, TGF-β, and arginase1. In most tumors, the infiltrated macrophages are considered to be of the M2 phenotype, which provides an immunosuppressive microenvironment for tumor growth. Furthermore, tumor-associated macrophages secrete many cytokines, chemokines, and proteases, which promote tumor angiogenesis, growth, metastasis, and immunosuppression. Recently, it was also found that tumor-associated macrophages interact with cancer stem cells. This interaction leads to tumorigenesis, metastasis, and drug resistance. So mediating macrophage to resist tumors is considered to be potential therapy.