Ethanol-induced liver cirrhosis continues to be a major cause of morbidity and mortality worldwide. Excess deposition of type I collagen in cirrhotic livers results mainly from the imbalance between its synthesis and degradation by liver stellate cells (LSC). Ethanol induces liver fibrosis by several mechanisms that include: a) changes in cellular redox, formation of free radicals, and increased lipoperoxidation, all of them contribute to the oxidative stress response. b) formation of acetaldehyde, an agent that by itself, induces the transcriptional activation of the mouse collagen gene (colla1) in LSC, and c) ethanol-induced liver injury which results in activation of Kupffer cells and arrival of inflammatory cells: cells produce growth factors and cytokines, such as IL6 and TGF-beta1, known to contribute to the fibrogenic process. Thus, the investigators developed a co-culture system consisting of hepatocytes and LSC, that mimics many of the physical and physiological relationships of these two cell types in vivo. The PI's preliminary data strongly indicate that while hepatocytes metabolize ethanol, LSC respond with increased production of type I collagen. Thus, their overall specific aims are: a) to define the acetaldehyde-, ethanol-, and TGF-beta1-responsive elements, b) to establish the role of c/EBPO on acetaldehyde-, ethanol and TGF-beta1-mediated upregulation of the colla1 gene. c) To demonstrate that H202, a product of the oxidative stress response, is a common second messenger induced by the three fibrogenic stimuli that plays a key role in the upregulation of the colla1 gene. d) The PI shall investigate whether there is a reciprocal modulation of the MMP-I and colla 1 genes. Their long-term goal is to define the key regulatory elements susceptible to therapeutic intervention involved in ethanol-induced liver fibrogenesis and develop new strategies, based on our findings, to induce Collagen degradation while inhibiting its production.
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