Effects of bacterial products on enterocyte–macrophage interactions in vitro

• Published in: Biochemical and biophysical research communications Vol. 413; no. 2; pp. 336 - 341
• Main Authors: Tyrer, Peter C., Bean, Elaine G., Ruth Foxwell, A., Pavli, Paul
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 23.09.2011
• Subjects: Acetylmuramyl-Alanyl-Isoglutamine - pharmacology; Bacteria; Caco-2 Cells; CD14 antigen; Cell migration; Cell Nucleus - drug effects; Cell Nucleus - ultrastructure; Coculture Techniques; Cytokines - metabolism; Data processing; Differentiation; Down-Regulation; Enterocytes; Enterocytes - drug effects; Enterocytes - physiology; Enterocytes - ultrastructure; Epithelial cells; Filters; Humans; Inflammation; Interleukin 1; Interleukin 8; Intestine; Lipopolysaccharide Receptors - metabolism; Lipopolysaccharides; Lipopolysaccharides - pharmacology; Macrophages; Macrophages - drug effects; Macrophages - physiology; Macrophages - ultrastructure; Monocytes; Monocytes - drug effects; Monocytes - physiology; Mucosal immunology; muramyl dipeptide; Pathogen-associated molecular pattern molecules; Peripheral blood; Pores; Tight Junctions; Tumor necrosis factor; Enterocytes; Monocytes; Pathogen-associated molecular pattern molecules; Macrophages; Intestine; Mucosal immunology
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1016/j.bbrc.2011.08.100

► Human blood monocytes cocultured with Caco-2 cells develop intestinal macrophage phenotype. ► LPS and MDP induce monocyte migration into cultures. ► LPS and MDP differentially affect secretion of inflammatory cytokines in cocultures. ► Monocyte/caco2 model has potential to study intestinal inflammatory processes. We describe a coculture model of a human intestinal epithelial cell line and human peripheral blood monocytes in which monocytes differentiate into cells with features of resident intestinal macrophages. Caco-2 cells are grown on the lower surface of a semipermeable filter with pore size of 3μm (Transwells®) until they differentiate into enterocytes. Peripheral-blood monocytes are added and the co-culture incubated for two days. Monocytes migrate through the pores of the membrane, come into direct contact with the basolateral surfaces of the epithelial cell monolayer, and develop characteristics of resident intestinal macrophages including downregulation of CD14 expression and reduced pro-inflammatory cytokine responses (IL-8, TNF and IL-1β) to bacterial products. The apical application of lipopolysaccharide (LPS) and muramyl dipeptide (MDP) resulted in an increased number of integrated monocytes, but abrogated the downregulation of CD14 expression and the diminished cytokine responses. MDP also reduced tight-junctional integrity, whilst LPS had no effect. These data indicate that LPS and MDP have significant pathophysiological effects on enterocyte–monocyte interactions, and confirm other studies that demonstrate that enterocytes and their products influence monocyte differentiation. This model may be useful in providing insights into the interaction between monocytes, epithelial cells and intestinal bacteria in health and disease.