Chronic alcohol use is the major cause of cirrhosis and liver failure in adult patients in the United States. In alcoholic liver disease, there is a strong correlation between the generation of free radicals and liver peroxidation projects and the induction of extracellular matrix proteins in fibrosis. Although the hepatic stellate cell (hsc, also called Ito cell or fat-storing cell) is the major cell that synthesizes the excess extracellular matrix proteins characteristic of cirrhosis, the mechanism of activation and perpetuation of the activated phenotype in the hsc is largely unknown. The activation of hscs is characterized by increases in both AP-l and NFkappaB transcription activity. These two transcriptional factors are induced by signaling processes that are responsive to oxidative stress. The underlying hypothesis of this proposal are that ethanol, acetylaldehyde, and/or LPS induce AP-l and NFkappaB in quiescent hscs, which is required for the initial activation. Subsequently, the ethanol-included cytokines, TNFalpha, TGFbeta, and/or IL-6 stimulate AP-1 and NFkappaB activity in the activated but not quiescent hscs. These hypothesis provide the foundation of a model on which the direct effects of ethanol provide the initial stimulus for signal transduction, which is perpetuated by the elevated cytokine levels ion alcoholic liver disease.
The specific aims to be addressed in this proposal are: 1)to determine the effect of ethanol. acetylaldehyde, and LPS on AP-l and NF-kappaB induction in quiescent and activated hepatic stellate cells, 2)to determine the effects of TNF-alpha, TGF-beta, and IL-6 on the induction of AP-l and TGF- beta, 3)induction on the expression of collagen alpha1(I), 4)to assess the effect of blocking NFkappaB and APJ-1 activity in quiescent and activated hscs on proliferation, activation state, and collagen expression and 5) to assess AP-1 and NFkappaB expression in target cells in the brain and liver upon chronic exposure to alcohol.
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