Hepatic cirrhosis, the leading cause of mortality due to liver disease, is characterized by the excessive and disorderly deposition of extracellular maxtrix in the liver. At present, it has no effective therapy. The proposed studies aim to characterize critical aspects of the excessive extracellular matrix deposition in cirrhosis. Hepatocytes respond to injury with increased synthesis and deposition of fibronectin in Disse's space. If the injury persists collagen type I is also deposited; in addition, in chronic injury a continuous basement membrane is formed. The proposed studies are designed to analyze four major points in the development of hepatic cirrhosis: 1). To obtain monospecific antibodies discriminating between the plasma and tissue forms of fibronectin. We will use the amino acid sequences known to be specific for cellular fibronectin to generate synthetic peptides that after conjugation with hemocyanin will be used as antigens. These antibodies will be used to determine if hepatocytes respond to injury by secreting, in addition to plasma fibronectin, cellular fibronectin. 2). To asses the effect of sinusoidal capillarization on hepatocyte uptake of circulating macromolecules. To this end we will use sialylated and asialylated proteins marked with electron-dense tracers, to measure their clearance from plasma and study by light and electron microscopy their fate in normal vs. cirrhotic livers. 3). To study, by light and electron microscopy immunohistochemistry, the changes in the hepatic extraceullar matrix during the regeneration that follows partial hepatectomy. In this manner we will compare extracellular matrix secretion and deposition in two processes, regeneration and cirrhosis, that although having some similarities have radically different outcomes. 4). To study by light microscopy immunohistochemistry the hepatic extracellular matrix in human alcoholic liver disease using available tissues embedded in paraffin. The changes found at different stages of the human disease will be compared with the more detailed sequence available from rats treated with CC14. To develop rational therapies for cirrhosis, we have to know which component(s) of the extracellular matrix modulate hepatocyte behavior and how to prevent their deposition or facilitate their removal. The proposed studies will address some critical aspects of this hepatocyte- extracellular matrix interaction.
