Hydrogen peroxide damage to rat liver sinusoidal endothelial cells is prevented by n-acetyl-cysteine but not GSH.

Abstract

Background: Reactive oxygen species (ROS) are prevalent in the liver during intoxication, infection, inflammation, and aging. Changes in liver sinusoidal endothelial cells (LSEC) are associated with various liver diseases.

Methods: Isolated rat LSEC were studied under oxidative stress induced by H2O2 at different concentrations (0.5-1000 µM) and exposure times (10-120 min). LSEC functions were tested in a dose-dependent and time-dependent manner.

Results: (1) Cell viability, reducing potential, and scavenging function decreased as H2O2 concentration and exposure time increased; (2) intracellular ROS levels rose with higher H2O2 concentrations; (3) fenestrations exhibited a dynamic response, initially closing but partially reopening at H2O2 concentrations above 100 µM after about 1 hour; (4) scavenging function was affected after just 10 minutes of exposure, with the impact being irreversible and primarily affecting degradation rather than receptor-mediated uptake; (5) the tubulin network was disrupted in high H2O2 concentration while the actin cytoskeleton appears to remain largely intact. Finally, we found that reducing agents and thiol donors such as n-acetyl cysteine and glutathione (GSH) could protect cells from ROS-induced damage but could not reverse existing damage as pretreatment with n-acetyl cysteine, but not GSH, reduced the negative effects of ROS exposure.

Conclusions: The results suggest that LSEC does not store an excess amount of GSH but rather can readily produce it in the occurrence of oxidative stress conditions. Moreover, the observed thresholds in dose-dependent and time-dependent changes, as well as the treatments with n-acetyl cysteine/GSH, confirm the existence of a ROS-depleting system in LSEC.