MODULATION OF ACUTE TOXIC LIVER INJURY

The underlying basis of liver disease is the hepatic failure that
results from hepatocyte injury and subsequent cell death. To be able to
prevent this hepatic damage, it is necessary to better understand the
mechanisms of hepatocyte injury. While the mechanisms of damage for
specific hepatotoxins have been well studied, the modulation of this
injury by external factors and cytoprotective proteins, has not been
well investigated. External factors involved in the process of acute
liver injury, such as the cytokines, tumor necrosis factor-alpha (TNF-
alpha) and interleukin-1 (IL-1), have begun to be identified. Our long-
term goal is to determine the roles of these modulators of acute liver
damage through the study of cell culture models and further in vivo
investigations, in order to understand the mechanisms of hepatic injury.
The specific aims of this proposal are: (1) To examine the role of TNF-
alpha, IL-1 and lipopolysaccharide (LPS) in acute liver damage. This
work will involve the use of an in vitro model of galactosamine (GalN)
liver injury using cultures of the hepatoma cell line HUH-7 alone, or in
coculture with the macrophage line U-937. This model will be used to
study the effects of TNF-alpha, IL-1, and LPS during toxic injury.
Additional investigations will examine the influences of macrophages on
these effects, as well as the mechanisms of cytokine toxicity. In vivo
studies will also further define the roles of LPS, TNF-alpha and IL-1.
(2) To investigate the function of anti-oxidant enzymes and
metallothionein (MT) in the protection against TNF-alpha IL-1 mediated
hepatocellular injury. These studies will also include an examination
of the in vivo models of CCl4 and GalN injury for changes in gene
expression and protein synthesis of potentially cytoprotective proteins.
(3) To determine additional cellular factors responsible for hepatocyte
resistance to oxidative injury. HUH-7 cells resistant to H2O2 will be
selected for the purpose of determining which genes are overexpressed in
these cells, and whether they mediate resistance to H2O2 and other forms
of oxidative stress.