Alcoholism is a major health problem in the United States since more than 15 million people are dependent on or abuse alcohol. A significant proportion of alcohol-related morbidity and mortality is a consequence of alcohol-induced liver disease (ALD). Studies have suggested that heavy alcohol consumption results in disruption of the mucosal intestinal epithelium which, in turn, leads to increased Gram negative bacteria] translocation and release of endotoxin (LPS) derived from these bacteria into the liver via the portal vein. Although the exact mechanisms of liver injury in ALD are currently unclear, reports have suggested that production and release of inflammatory cytokines by hepatic macrophages (Kupffer cells) contribute to and help to sustain ALD. However, it is also possible that lamina propria macrophages are a primary target of alcohol effects, given their proximity to alcohol-induce epithelial cell damage. Apart from studies showing altered barrier function and increased bacterial translocation, little is known about the effects of alcohol on the capacity of intestinal epithelial cells or lamina propria macrophages to be stimulated by either translocating bacteria or their LPS to secrete inflammatory products. Circulation of these intestinal-derived cytokines to the liver could contribute to hepatic damage either directly or indirectly via their effects on Kupffer cells, hepatocytes, or endothelial cells within the liver. Thus, intestinal macrophages could play a much broader role in the initiation of ALD than heretofore considered. To address these issues, the following Specific Aims are proposed: 1) To evaluate the effects of alcohol and normal intestinal bacteria or LPS in co-cultures of intestinal epithelial cells and macrophages. In vitro cocultures of epithelial cells and macrophages will be analyzed in the absence or presence of ethanol for cytokine secretion, nitrite production, and expression of specific LPS-inducible genes upon stimulation with E. coli or E coli LPS; and, 2) Mice fed alcohol-enriched or isocalorically-matched control diets will be euthanized at various times to validate augmented translocation and to analyze intestinal and liver sections for induction of inflammatory (LPS-inducible) gene products by semi-quantitative RT-PCR. It is anticipated that these studies will identify specific cytokines and/or genes whose expression is (are) dysregulated by alcohol. Such results would suggest that tissue damage associated with ALD could be mitigated by targeting specific LPS-induced cytokines or gene products.
| Fleming, S; Toratani, S; Shea-Donohue, T et al. (2001) Pro- and anti-inflammatory gene expression in the murine small intestine and liver after chronic exposure to alcohol. Alcohol Clin Exp Res 25:579-89 |
