The effects of oxidative stress on the liver sieve.

BACKGROUND/AIMS: Oxidative stress is implicated in the pathogenesis of age-related and disease-associated changes in the hepatic sinusoid. We studied the effects of oxidative stress on the morphology of the liver, focusing specifically on the hepatic sinusoidal endothelium (the 'liver sieve').
METHODS: The effects of tert-butyl hydroperoxide on the intact liver and isolated sinusoidal endothelial cells were assessed by electron microscopy, immunohistochemistry and biochemical analysis.
RESULTS: Immunohistochemistry revealed a dose-dependent increase in peri-sinusoidal 3-nitrotyrosine staining, particularly in the regions adjacent to the portal triads. Electron microscopy showed dose-dependent formation of large intracellular gaps in the sinusoidal endothelium with reduction in the diameter of the remaining endothelial fenestrations. Activated Kupffer cells extending processes through the fenestrations to contact hepatocytes were noted. Biochemical analysis of total liver tissue showed no significant changes in malondialdehyde content but a decrease in the ratio of GSH to GSSG. tert-Butyl hydroperoxide administered directly onto isolated liver sinusoidal endothelial cells was associated with similar gap formation, indicating a direct effect on the endothelial cells by tert-butyl hydroperoxide.
CONCLUSIONS: Oxidative stress selectively damages hepatic sinusoidal endothelial cells. This has implications for those processes associated with changes in the sinusoidal endothelium such as ageing, cirrhosis and exposure to hepatotoxins.