The preventive effects of OK432 on endotoxin-induced liver injury: liver protection by the modulation of hepatic macrophage function

Digest

Dr Keizo Sugimachi, Editor-in-Chief of Surgery Today (The Japanese Journal of Surgery), has selected from the January, February and March 1996 issues of his journal for this quarter's digest. A digest of BJS for the same period written by Mr Colin Johnson, European Editor, appears in the Japanese journal.

Endotoxin induces structure-function alterations of rat liver peroxisomes: Kupffer cells released factors as possible modulators

We report that endotoxin treatment results in decreased amounts of peroxisomes as well as changes in structure and function of peroxisomal membranes. Peroxisomes isolated from the liver of control and treated animals showed a marked decrease in total protein, but no significant alteration in the sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) protein profile. However, the Western blot study of the peroxisomal beta-oxidation enzymes and catalase showed an increase in those enzymes in the peroxisomal peak of normal density in endotoxin-treated rats. Disintegration of peroxisomal membranes by carbonate treatment from endotoxin-treated liver and change in the fluidity of peroxisomal membranes suggests alterations in peroxisomal membrane structure. No such alterations were found in mitochondrial or microsomal membranes of endotoxin-treated livers. The lipid analysis of these organelles showed that the only organelle affected was the peroxisome, with a significant decrease in the phospholipid and cholesterol concentrations. To understand the mechanism of endotoxin-mediated alterations in peroxisomes, we studied the possible role of Kupffer cell secreted soluble factors (tumor necrosis factor alpha [TNF-alpha]) on the peroxisomal structure/function. Inactivation/elimination of Kupffer cells by gadolinium chloride before endotoxin treatment did not normalize the overall peroxisomal protein amount and the lipid composition of isolated peroxisomes. However, the levels of individual protein amount in remaining peroxisomes were normalized. Endotoxin also decreased peroxisomal beta-oxidation, and this was partially restored with gadolinium treatment. These results clearly show that peroxisomes are severely affected by endotoxin treatment and suggest that the damage to this organelle may contribute, at least in part, to endotoxin-induced hepatic cytotoxicity.

Continuous hepatocyte growth factor supply prevents lipopolysaccharide-induced liver injury in rats

We present a rat model in which continuous supply of hepatocyte growth factor (HGF) prevents liver injury induced by carbon tetrachloride (CCl4) and E. coli 011:B4 lipopolysaccharide (LPS). Rat fibroblasts genetically modified to secrete rat HGF were implanted in syngenic rat spleen 7 days before administration of the hepatotoxins. Rats with HGF-secreting fibroblasts in the spleen showed a dramatic resistance to CCl4- and LPS-induced liver injury. In the LPS-induced liver injury model, blood chemical analysis revealed that the increase in serum glutamic oxalacetic transaminase level and the decrease in blood sugar level were remarkably suppressed in rats with HGF-secreting cells in the spleen. Most importantly, their survival rate was greatly improved compared to other control groups of rats. Thus our results indicate a new role of HGF in liver protection during endotoxemia and convey important clinical implications for developing new therapeutic modalities in the treatment of liver failure caused by endotoxemia.