AJP - Cell Physiology, Vol 266, Issue 6 C1552-C1559, Copyright © 1994 by American Physiological Society
Integrin-mediated adhesive properties of uroepithelial cells are inhibited by treatment with bacterial toxins
A. Elgavish, A. Pattanaik, K. Lloyd and R. Reed
Department of Comparative Medicine, University of Alabama at Birmingham Medical School 35294.
Gram-negative bacteria are a dominant cause of urinary tract infection, and
their ability to produce toxins is an important virulence attribute.
Cellular mechanisms triggered by the production of toxins in the lower
urinary tract have not been completely defined. Ureteral epithelial cells
(UT; A. Elgavish, Infect. Immun. 61: 3304-3312, 1993) have served as an in
vitro model to explore the possibility that bacterial toxins act on UT by
affecting integrin-mediated adhesive properties. The effect of treatment
with lipopolysaccharides (LPS) from three strains of the gram-negative
Escherichia coli [055:B5 (LPS-1), 0111:B4 (LPS-4), and 0127:B8 (LPS-5)] and
lipoteichoic acids from two gram-positive bacteria, Streptococcus faecalis
(LT-2) and Bacillus subtilis (LT-3), were examined. LPS-5 inhibited
markedly UT attachment to collagen and fibronectin. LPS-4 had no effect,
whereas LPS-1 inhibited UT attachment to collagen but not to fibronectin.
The fact that LPS-5 and LT-2 inhibited an Arg-Gly-Asp sequence-sensitive
component of UT attachment to fibronectin is consistent with the
possibility that these toxins acted via a mechanism involving typical
fibronectin receptors. UT spreading was inhibited markedly by LPS-1, LT-2,
and LT-3, whereas LPS-4 and LPS-5 had no effect. Because clustering of
integrins is a crucial step in integrin-mediated signal transduction, the
possibility that toxins inhibited spreading by affecting clustering was
tested. Treatment with LT-2, which inhibited spreading dramatically,
abolished completely a UT cell population containing more than five to
eight beta 1- or beta 4-subunit-containing integrin clusters.(ABSTRACT
TRUNCATED AT 250 WORDS)
