Date on Master's Thesis/Doctoral Dissertation

12-2012

Document Type

Master's Thesis

Degree Name

M.S.

Department

Pharmacology and Toxicology

Committee Chair

Arteel, Gavin Edward

Author's Keywords

Liver; alcohol; integrins

Subject

Alcohol--Physiological effect; Liver; Mice--Physiology

Abstract

Background. Progression of alcoholic liver disease (ALD) is associated with an increase in fibrin extracellular matrix (ECM) and inflammation. Previous studies have shown that this accumulation of fibrin in ALD is mediated by impaired fibrinolysis. Additionally, it is known that fibrin(ogen) interacts with the av~3 integrin of endothelial cells. The purpose of this study was to test the hypothesis that hepatic inflammation caused by alcohol is mediated, at least in part, by activation of integrin av~3 by fibrin(ogen). To test this hypothesis, a study was designed to determine the effect of cycloRGDN, a peptide inhibitor of integrin av~3, in a mouse model of lipopolysaccharide (LPS)-induced inflammation enhanced by ethanol pre-exposure. Methods. Accordingly, male C57BLl6J mice were exposed to ethanol (6 g/kg i.g.) or isocaloric/isovolumetric maltose dextrin solution for 3 days and injected with lipopolysaccharide (LPS; 10 mg/kg i.p.) 24 hours after the last dose of ethanol. Some animals received the avß3 integrin inhibitor (cycloRGDN; 3 mg/kg i.p.) 1 hour prior to LPS administration. Animals were sacrificed 8 or 24 hours after LPS administration. Liver damage was assessed by plasma (AL T, AST) and histological indices of liver damage (hematoxylin and eosin; H&E) and inflammation (chloroacetate esterase; CAE). Results. Ethanol pre-exposure enhanced liver injury due to LPS, as indicated by a significant increase in plasma AL T levels. cycloRGDN significantly attenuated the increase in plasma AL T caused by ethanol pre-exposure. These results were supported by histological changes. Animals that received ethanol and LPS had both larger and more numerous necroinflammatory foci compared to animals that received LPS alone. The number and severity of necroinflammatory foci was reduced by cycloRGDN compared to LPS + ethanol. Ethanol pre-exposure enhanced the increase in neutrophil migration caused by LPS, as determined by CAE staining. Animals administered cycloRGDN had fewer infiltrating neutrophils compared to those that received a combination of ethanol and LPS. Conclusions. These data suggest that cycloRGDN administration protects against liver injury caused by a combination of alcohol and LPS exposure. CycloRGDN also blunts ethanol-enhanced neutrophil infiltration caused by LPS in this model. Therefore, integrin avß3 may play an important role in enhanced hepatic inflammation and injury due to LPS after ethanol pre-exposure.

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