Although alcoholic liver disease (ALD) is a major public health problem how alcohol stimulates inflammatory damage in the liver is poorly understood. Alcoholic hepatitis (AH), characterized by chronic inflammation and parenchymal infiltration by T cells and neutrophils via the sinusoids, is a critical determinant of disease progression. Circulating lymphocytes must recognize and bind to endothelial cells before they can enter tissue and there is evidence that specific combinations of chemokines and adhesion molecules regulate binding to sinusoidal endothelium including the novel adhesion molecule VAP-1 and CXCRS-binding chemokines, all of which show increased he expression in AH. VAP-1 is a monoamine oxidase and its enzymic activity appears to be critical for its adhesive function. We have developed an in vitro model in which human sinusoidal endothelial cells are grown under conditions of blood flow that mirror those in vivo allowing us to study lymphocyte interactions with endothelium at physiological flow rates. In addition we have adapted this assay for co-cultures of endothelial cells and hepatocytes or Kupffer cells allowing us to study the contribution of cell types on lymphocyte recruitment in response to alcohol.
Specific aims are: 1) to determine if lymphocytes from patients with AH show increased adhesion to sinusoidal endothelium and if so to demonstrate the molecules involved, 2) to define the role of specific molecules including VAP-1 and CXCR3 in this process, 3) to use flow-based co-cultures to determine if alcohol and acetaldehyde activate sinusoidal endothelium and lymphocyte transmigration directly or via paracrine effects mediated by Kupffer cells or hepatocytes, 4) to define the role of NFkB signaling in ethanol mediated endothelial activation. These studies are unique because they investigate the adhesion of human cells under flow. They offer us the opportunity to determine the molecules involved in liver-infiltration in alcoholic hepatitis and how alcohol and its metabolites activate these processes. Understanding the molecular basis of lymphocyte adhesion to sinusoidal endothelium in ALD will elucidate the pathogenesis of liver damage and may suggest new therapeutic targets to prevent tissue-damage in response to alcohol.
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