epidermal-growth-factor and Peritonitis

Systemic administration of epidermal growth factor (EGF) decreases mortality in a murine model of septic peritonitis. Although EGF can have direct healing effects on the intestinal mucosa, it is unknown whether the benefits of systemic EGF in peritonitis are mediated through the intestine. Here, we demonstrate that enterocyte-specific overexpression of EGF is sufficient to prevent intestinal barrier dysfunction and improve survival in peritonitis. Transgenic FVB/N mice that overexpress EGF exclusively in enterocytes (IFABP-EGF) and wild-type (WT) mice were subjected to either sham laparotomy or cecal ligation and puncture (CLP). Intestinal permeability, expression of the tight junction proteins claudins-1, -2, -3, -4, -5, -7, and -8, occludin, and zonula occludens-1; villus length; intestinal epithelial proliferation; and epithelial apoptosis were evaluated. A separate cohort of mice was followed for survival. Peritonitis induced a threefold increase in intestinal permeability in WT mice. This was associated with increased claudin-2 expression and a change in subcellular localization. Permeability decreased to basal levels in IFABP-EGF septic mice, and claudin-2 expression and localization were similar to those of sham animals. Claudin-4 expression was decreased following CLP but was not different between WT septic mice and IFABP-EGF septic mice. Peritonitis-induced decreases in villus length and proliferation and increases in apoptosis seen in WT septic mice did not occur in IFABP-EGF septic mice. IFABP-EGF mice had improved 7-day mortality compared with WT septic mice (6% vs. 64%). Since enterocyte-specific overexpression of EGF is sufficient to prevent peritonitis-induced intestinal barrier dysfunction and confers a survival advantage, the protective effects of systemic EGF in septic peritonitis appear to be mediated in an intestine-specific fashion.

Topics: Animals; Apoptosis; Bacterial Translocation; Cell Proliferation; Claudins; Cytokines; Disease Models, Animal; Enterocytes; Epidermal Growth Factor; Fatty Acid-Binding Proteins; Intestinal Mucosa; Intestines; Membrane Proteins; Mice; Mice, Transgenic; Peritonitis; Permeability; Rats; RNA, Messenger; Tight Junctions

Human peritoneal mesothelial cells lie on a basement membrane-like material consisting of fibronectin (FN), type I collagen (CI), type III collagen (CIII) and laminin (LA). To understand how these extracellular matrix (ECM) proteins affect mesothelial cell behavior, we investigated their effect on the adhesion and proliferation of mesothelial cells. A modified methyltetrazolium dye method was used to assess cell number. The results showed that FN, CI, CIII and LA, all increased adhesion of mesothelial cells. The adhesive effect was blocked dose-dependently by a synthetic Arg-Gly-Asp-containing (RGD) peptide. When coated as a substratum (immobilized form), FN, CI, CIII and LA, all enhanced serum-stimulated and epidermal-growth-factor-stimulated cellular proliferation as compared with bovine-serum-albumin-blocked plastic surfaces. When added in a soluble form, all matrix proteins except FN inhibited serum-stimulated and epidermal-growth-factor-stimulated cellular proliferation at high concentrations (CI and CIII: 1-10 micrograms/ml, LA: 3-10 micrograms/ml). We conclude that peritoneal mesothelial cells possess an RGD-sensitive receptor and that the ECM can modulate adhesion and proliferation of peritoneal mesothelial cells. The growth-modulating effect depends on the form and concentration of the ECM proteins.

Topics: Cell Adhesion; Cell Communication; Cell Division; Cells, Cultured; Epidermal Growth Factor; Epithelial Cells; Extracellular Matrix; Extracellular Matrix Proteins; Humans; Peritoneal Cavity; Peritonitis