Bacterial Wall Components such as Lipothecoid Acid, Peptidoglycan, Liposaccharide and Lipid A Stimulate Cell Proliferation in Intestinal Epithelial Cells

Abstract

Earlier studies indicate that the micro ora contains mitogens to intestinal epithelial cells. Our aim is to examine whether cell wall components of both Gram-negative and positive bacteria in uence cell proliferation in small intestinal and colonic epithelial cells. A human colonic epithelial cell line from adenocarcinoma (IEC-6) and a nontransformed small intestinal cell line from germ-free rats (LS-123) were incubated with (a) lipothecoid acid from Streptococcus faecalis at 1.56 -50 mg:ml, (b) peptidoglycan from Staphylococcus aureus at 0.1 -7.5 mg:ml, (c) lipopolysaccharides (LPS) from Escherichia coli, Klebsiella pneumonia and Pseudomona aeruginosa at 0.1 -7.5 m g:ml, (d) lipid A from Escherichia coli at 0.016 -50 m g:ml. The cells were labelled with tritiated thymidine and processed for autoradiography. DNA synthesis was estimated by the labelling index.Cell wall components of Gram-positive bacteria (LTA from Streptococcus faecalis and peptidoglycan from Staphylococcus aureus) moderately increased the DNA synthesis in both cell lines (p B0.001). Similarly, cell wall components of Gram-negative bacteria (LPS of Escherichia coli, Klebsiella pneumonia and Pseudomona aeruginosa and lipid A of Escherichia coli increased the labelling index in IEC-6 and LS-123 cells (p B0.001).Thus, this study identi es mitogens present in both Gram-positive and Gram-negative bacteria that increase cell proliferation in rat and human intestinal cells. Our ndings support a role for the micro ora in the regulation of cell proliferation in both health and disease.