Reciprocal regulation of endothelial substrate adhesion and barrier function.
OBJECTIVE
To examine how cell-substrate adhesion is regulated during barrier changes produced by exposure to inflammatory mediators.


METHODS
Lung microvascular endothelial monolayers were treated with test agents +/- blockers, and barrier was measured by transendothelial resistance; cell-substrate adhesion was assessed by surface area conservation after trypsin treatment of monolayers. Protein phosphorylation and distribution were assayed by immunoblotting and fluorescent microscopy, respectively.


RESULTS
H2O2, histamine, bradykinin, and thrombin, decreased endothelial barrier function, and enhanced adhesion to the substratum. H2O2 enhanced cell adhesion to the substrate in a concentration (0-1 mM)- and time (0-60 minutes)-dependent fashion. This effect of H2O2 reversed within 120 minutes of removal of H2O2 and was blocked by the mean arterial pressure (MAP) kinase inhibitor, PD98059 and by chelating cytoplasmic Ca2+ but not PKC or PKG inhibition. H2O2 also stimulated tyrosine phosphorylation of several proteins and increased the association of the focal adhesive proteins paxillin, talin, and vinculin with the cytoskeleton and may promote localization of these proteins to junctions.


CONCLUSIONS
Our data indicate that inflammatory mediators reduce cell-cell contact, contributing to reduced solute barrier and simultaneously enhanced substrate binding, which may be reciprocal events in barrier regulation in vitro and in vivo.
Alexander
J S
JS
Department of Molecular and Cellular Physiology, Louisiana State University, Health Sciences Center, Shreveport, LA 71130, USA. jalexa@lsumc.edu
Zhu
Y
Y
Elrod
J W
JW
Alexander
B
B
Coe
L
L
Kalogeris
T J
TJ
Fuseler
J
J
D000818:Animals; D001920:Bradykinin / Q000494:pharmacology; D002199:Capillary Permeability / Q000187:drug effects*; D021982:Cell-Matrix Junctions / Q000187:drug effects* / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000187:drug effects / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D022001:Focal Adhesions / Q000187:drug effects* / Q000378:metabolism; D006632:Histamine / Q000494:pharmacology; D006861:Hydrogen Peroxide / Q000494:pharmacology; D018836:Inflammation Mediators / Q000494:pharmacology*; D008168:Lung / Q000166:cytology; D051379:Mice; D008810:Mice, Inbred C57BL; D013917:Thrombin / Q000494:pharmacology
D003598:Cytoskeletal Proteins; D018836:Inflammation Mediators; D006632:Histamine; D006861:Hydrogen Peroxide; D013917:Thrombin; D001920:Bradykinin