Omega 3-lipid peroxides injure CaCo-2 cells: relationship to the development of reduced glutathione antioxidant systems.

BACKGROUND/AIMS: Dietary polyunsaturated fats are significant sources of luminal lipid hydroperoxides whose accumulation can be injurious to the intestinal epithelium. The current study examines the cytotoxicity of peroxidized fish oil to CaCo-2 cells.

METHODS

Chromate release from cells was used as an index of CaCo-2 injury, and day 1 and day 7 postconfluent monolayers were used to represent the immature and mature states, respectively.

RESULTS

Air oxidation of fish oil yielded equimolar quantities of hydroperoxyeicosapentaenoic (20:5) and docosahexaenoic (22:6) acids. Their cytotoxicity were time- and concentration-dependent and were related to the developmental stages. A 100-mumol/L dose of hydroperoxides caused a 40% and a 15% 51Cr release from day 1 and day 7 cells, respectively. Cellular glutathione (GSH), GSH redox enzyme, and gamma-glutamyl cysteine synthetase activities were significantly lower in day 1 than in day 7 cells, indicating that hydroperoxide metabolism in immature cells is rate limited by reductant supply. GSH supplementation increased cell GSH in day 7 cells (twofold) but not in day 1 cells, suggesting a limited ability of immature cells to use exogenous GSH.

CONCLUSIONS

These results show that nondifferentiated cells are more sensitive to oxidant-induced injury than mature cells. This enhanced susceptibility is associated with a lower GSH-dependent detoxication capacity of the immature cells.