Gamma interferon augments the intracellular pathway for lipopolysaccharide (LPS) recognition in human intestinal epithelial cells through coordinated up-regulation of LPS uptake and expression of the intracellular Toll-like receptor 4-MD-2 complex

Infect Immun. 2003 Jun;71(6):3503-11. doi: 10.1128/IAI.71.6.3503-3511.2003.

Abstract

Although some intestinal epithelial cell lines are known to respond to lipopolysaccharide (LPS), understanding of the relationship between LPS responsiveness and the expression of LPS receptors or factors regulating LPS responsiveness of intestinal epithelial cell lines is incomplete. In this study, we demonstrate that commonly studied human intestinal epithelial cell lines can be classified into at least three different types on the basis of LPS responsiveness, Toll-like receptor-4 (TLR4) expression, and the effects of gamma interferon (IFN-gamma) on LPS responsiveness. The first phenotype, which includes the HCT-116 and Caco-2 cell lines, is characterized by relative hyporesponsiveness to LPS and diminished expression of TLR4 protein. In these cells, IFN-gamma does not induce LPS responsiveness. The second phenotype, which includes cell line SW480, exhibits a highly LPS-responsive phenotype and surface expression of TLR4 protein even in unprimed conditions. These lines are functionally similar to cells of monocytic lineage. In the third phenotype, which includes the HT-29 and Colo205 cell lines, TLR4 protein is largely present in the cytoplasmic fraction and the cells are hyporesponsive to LPS in an unprimed condition. However, priming of these cells with IFN-gamma can induce LPS responsiveness through augmentation of LPS uptake and expression of MD-2 mRNA and intracellular TLR4 proteins. Finally, these findings suggest that the Th1 cytokine IFN-gamma modulates LPS responsiveness through several mechanisms in intestinal epithelial cells and that these cells may comprise different subpopulations with distinct roles in innate immune responses.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Antigens, Surface / analysis
  • Antigens, Surface / genetics
  • Antigens, Surface / physiology*
  • Cell Line
  • Humans
  • Interferon-gamma / pharmacology*
  • Intestinal Mucosa / drug effects*
  • Intestinal Mucosa / metabolism
  • Lipopolysaccharide Receptors / analysis
  • Lipopolysaccharides / metabolism
  • Lipopolysaccharides / toxicity*
  • Lymphocyte Antigen 96
  • Membrane Glycoproteins / analysis
  • Membrane Glycoproteins / genetics
  • Membrane Glycoproteins / physiology*
  • RNA, Messenger / analysis
  • Receptors, Cell Surface / analysis
  • Receptors, Cell Surface / genetics
  • Receptors, Cell Surface / physiology*
  • Toll-Like Receptor 4
  • Toll-Like Receptors
  • Up-Regulation

Substances

  • Antigens, Surface
  • LY96 protein, human
  • Lipopolysaccharide Receptors
  • Lipopolysaccharides
  • Lymphocyte Antigen 96
  • Membrane Glycoproteins
  • RNA, Messenger
  • Receptors, Cell Surface
  • TLR4 protein, human
  • Toll-Like Receptor 4
  • Toll-Like Receptors
  • Interferon-gamma