Fibronectin attenuates the increased endothelial monolayer
permeability after exposure to rgd peptides, anti-[alpha]5[beta]1, or
tnf-[alpha]1.
Curtis, Theresa M., Paula J. McKeown-Longo, Peter A. Vincent, Suzanne
M. Homan, Erin M. Wheatley, and Thomas M. Saba.
Department of Physiology and Cell Biology, Neil Hellman Medical
Research Building, Albany Medical College, Albany, New York 12208
APStracts 2:0060L, 1995.
Endothelial permeability can be altered by tumor necrosis factor
[alpha] (TNF-[alpha]), a cytokine released in association with
inflammation-induced tissue injury. In the subendothelial matrix,
fibronectin (Fn) influences endothelial cell adhesion by the
interaction of integrins with RGD and non-RGD attachment sites in Fn.
We compared the effect of TNF-[alpha], RGD containing peptides
(GRGDSP), or antibody to [alpha]5[beta]1 integrins on the protein
permeability of bovine lung endothelial monolayers as assessed by
transendothelial 125I-albumin clearance. We also examined the
influence of purified human plasma fibronectin (HFn) on this
permeability response. TNF-[alpha], RGD peptides, and antibodies to
[alpha]5[beta]1 integrins elicited a dose- and time-dependent
increase in protein permeability as well as a reorganization and/or
disruption of the endogenous Fn matrix. A control RGE peptide
(GRGESP) as well as IgG purified from non-immune rabbit serum did not
increase endothelial protein permeability or disrupt the endogenous
fibrillar Fn pattern in the matrix. Likewise, a LDV peptide derived
from the alternatively spliced type III connecting segment (IIICS)
within bovine Fn (BFn) was unable to increase permeability of the
bovine endothelial monolayer. Co-incubation of purified soluble HFn
(300 or 600 [mu]g/ml) with either TNF-[alpha], the RGD peptide, or
the antibody to [alpha]5[beta]1 integrins prevented the increase in
endothelial permeability. This protective effect was also observed
when the purified HFn (600 _g/ml) was added after the TNF-[alpha]
induced increase in endothelial permeability had taken place.
Immunofluorescent analysis confirmed the incorporation of the HFn
into the subendothelial matrix and its co-localization with the
endogenous BFn. The similar alteration of the subendothelial matrix
after exposure to RGD peptides, anti-[alpha]5[beta]1 antibodies, or
TNF-[alpha] coupled with the ability for HFn to attenuate the
permeability increase typically elicited by all 3 agents, suggests
that disruption of cell-matrix interactions may be the mechanism by
which TNF-[alpha] alters endothelial permeability.
Received 18 May 1994; accepted in final form 6 April 1995.
APS Manuscript Number L143-4.
Article publication pending Am. J. Physiol. (Lung Cell. Mol.
Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 25 April 1995.