Alteration of culture regime modifies antioxidant defenses independent of intracellular reactive oxygen levels and resistance to severe oxidative stress within confluent Caco-2 "intestinal cells"

Reactive oxygen species are implicated in the development of gastrointestinal pathologies. Caco-2 monolayers are routinely used to study intestinal oxidative stress and its potential amelioration by pharmacological agents or dietary micronutrients. Little is known of the plasticity of Caco-2 antioxidant defenses with changes in culture conditions. We examined whether the frequency of culture media renewal alters the antioxidant-prooxidant status and integrity of Caco-2 monolayers. In comparison to monolayers subject to daily media renewal, increasing periods between media exchange resulted in varying degrees of suppression of catalase, glutathione reductase, and glutathione-S-transferase activity. No significant chan ses to superoxide dismutase activity, total glutathione, or intracellular ROS profiles were observed. Alkaline phosphatase activity, as a marker of differentiation, and mean monolayer cell population size were also unaffected. We suggest that Caco-2 antioxidant enzyme activities are differentially sensitive to changes in culture conditions. Studies employing this cell line for antioxidant-oxidative stress interactions will need to evaluate responses with respect to culture regime.