Epidermal growth factor prevents acetaldehyde-induced paracellular permeability in Caco-2 cell monolayer.
BACKGROUND
Intestinal permeability and endotoxemia play a crucial role in the pathogenesis of alcoholic liver disease. Previous studies showed that acetaldehyde disrupts intestinal epithelial barrier function and increases paracellular permeability by a tyrosine kinase-dependent mechanism. In the present study, the role of epidermal growth factor (EGF) in protection of epithelial barrier function from acetaldehyde was evaluated in Caco-2 intestinal epithelial cell monolayer.


METHODS
Caco-2 cells on Transwell inserts were exposed to acetaldehyde in the absence or presence of EGF, and the paracellular permeability was evaluated by measuring transepithelial electrical resistance and unidirectional flux of inulin. Integrity of epithelial tight junctions and adherens junctions was analyzed by confocal immunofluorescence microscopy and immunoblot analysis of occludin, zonula occludens (ZO)-1, E-cadherin, and beta-catenin in the actin cytoskeleton. Reorganization of actin cytoskeletal architecture was examined by confocal microscopy.


RESULTS
Acetaldehyde increased paracellular permeability to inulin and lipopolysaccharide, and EGF significantly reduced these effects of acetaldehyde in a time- and dose-dependent manner. EGF prevented acetaldehyde-induced reorganization of occludin, ZO-1, E-cadherin, and beta-catenin from the cellular junctions to the intracellular compartments. Acetaldehyde treatment induced a reorganization of actin cytoskeletal network and reduced the levels of occludin, ZO-1, E-cadherin, and beta-catenin associated with the actin cytoskeleton. EGF effectively prevented acetaldehyde-induced reorganization of actin cytoskeleton and the interaction of occludin, ZO-1, E-cadherin, and beta-catenin with the actin cytoskeleton.


CONCLUSIONS
These results indicate that EGF attenuates acetaldehyde-induced disruption of tight junctions and adherens junctions and prevents acetaldehyde-induced reorganization of actin cytoskeleton and its interaction with occludin, ZO-1, E-cadherin, and beta-catenin.
Sheth
P
P
Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee, USA.
Seth
A
A
Thangavel
M
M
Basuroy
S
S
Rao
R K
RK
D000079:Acetaldehyde / Q000037:antagonists & inhibitors* / Q000494:pharmacology*; D018938:Caco-2 Cells; D002463:Cell Membrane Permeability / Q000187:drug effects / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D006801:Humans; D007408:Intestinal Absorption / Q000187:drug effects / Q000502:physiology*
D004815:Epidermal Growth Factor; D000079:Acetaldehyde