title: Effects of bacterial products on enterocyte-macrophage interactions in vitro.
abstract: 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 3 μm (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.
authors: Inflammatory Bowel Disease Research Group, Level 5, Building 10, The Canberra Hospital, Yamba Drive, Garran, ACT 2606, Australia. peter.tyrer@otago.ac.nz
authors: Peter C
authors: PC
authors: Tyrer
authors: Elaine G
authors: EG
authors: Bean
authors: A
authors: A
authors: Ruth Foxwell
authors: Paul
authors: P
authors: Pavli
mesh_terms: D000119:Acetylmuramyl-Alanyl-Isoglutamine / Q000494:pharmacology*; D001419:Bacteria; D018938:Caco-2 Cells; D002467:Cell Nucleus / Q000187:drug effects / Q000648:ultrastructure; D018920:Coculture Techniques; D016207:Cytokines / Q000378:metabolism; D015536:Down-Regulation; D020895:Enterocytes / Q000187:drug effects* / Q000502:physiology / Q000648:ultrastructure; D006801:Humans; D018950:Lipopolysaccharide Receptors / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008264:Macrophages / Q000187:drug effects* / Q000502:physiology / Q000648:ultrastructure; D009000:Monocytes / Q000187:drug effects / Q000502:physiology; D019108:Tight Junctions
chemical_list: D016207:Cytokines; D018950:Lipopolysaccharide Receptors; D008070:Lipopolysaccharides; D000119:Acetylmuramyl-Alanyl-Isoglutamine