Colonic macrophage polarization in homeostasis, inflammation, and cancer

• Published in: American journal of physiology: Gastrointestinal and liver physiology Vol. 311; no. 1; pp. G59 - G73
• Main Authors: Isidro, Raymond A., Appleyard, Caroline B.
• Format: Journal Article
• Language: English
• Published: United States American Physiological Society 01.07.2016
• Subjects: Animals; Anti-Inflammatory Agents - therapeutic use; Antineoplastic Agents - therapeutic use; Cell Differentiation; Cell Lineage; Colon - drug effects; Colon - metabolism; Colon - microbiology; Colon - pathology; Colorectal cancer; Colorectal Neoplasms - drug therapy; Colorectal Neoplasms - metabolism; Colorectal Neoplasms - microbiology; Colorectal Neoplasms - pathology; Gastrointestinal Microbiome; Genotype & phenotype; Homeostasis; Humans; Inflammation Mediators - metabolism; Inflammatory bowel disease; Inflammatory Bowel Diseases - drug therapy; Inflammatory Bowel Diseases - metabolism; Inflammatory Bowel Diseases - microbiology; Inflammatory Bowel Diseases - pathology; Leukocytes; Macrophages - drug effects; Macrophages - metabolism; Macrophages - microbiology; Macrophages - pathology; Phenotype; Probiotics - therapeutic use; Reviews; Signal Transduction; colon; macrophage polarization; macrophages; colorectal cancer; inflammatory bowel disease
• ISSN: 0193-1857; 1522-1547; 1522-1547
• DOI: 10.1152/ajpgi.00123.2016

Our review focuses on the colonic macrophage, a monocyte-derived, tissue-resident macrophage, and the role it plays in health and disease, specifically in inflammatory conditions such as inflammatory bowel disease and cancer of the colon and rectum. We give special emphasis to macrophage polarization, or phenotype, in these different states. We focus on macrophages because they are one of the most numerous leukocytes in the colon, and because they normally contribute to homeostasis through an anti-inflammatory phenotype. However, in conditions such as inflammatory bowel disease, proinflammatory macrophages are increased in the colon and have been linked to disease severity and progression. In colorectal cancer, tumor cells may employ anti-inflammatory macrophages to promote tumor growth and dissemination, whereas proinflammatory macrophages may antagonize tumor growth. Given the key roles that this cell type plays in homeostasis, inflammation, and cancer, the colonic macrophage is an intriguing therapeutic target. As such, potential macrophage-targeting strategies are discussed.