Immunobiology of monocytes and macrophages in inflammatory bowel disease

Abstract

Monocytes are circulating blood cells that play important roles in innate immunity to pathogens and regulate the inflammatory response. Dendritic cells (DC) can initiate and regulate the highly pathogen-specific adaptive immune responses and are critical to the development of immunologic memory and tolerance. Along with tissue macrophages together they can be involved with the pathogenesis of inflammatory diseases, in many areas of the body including skin, brain, vascular system, and intestines. Monocyte and macrophage cellular heterogeneity has been recognized, but more recently investigators have identified three functional subsets of human monocytes and two subsets of mouse monocytes. They are able to exert specific roles in homeostasis and inflammation/immunity in vivo. Functional characterization of myeloid cells, including tissue resident macrophages, is in progress in both humans and rodents and will provide a better understanding of the pathophysiology of inflammatory diseases.