Membrane peroxidation by lipopolysaccharide and iron-ascorbate adversely affects Caco-2 cell function: Beneficial role of butyric acid

Abstract

Background: Membrane lipid peroxidation may play a role in immune-mediated bowel diseases. Objective: We examined the effects of lipopolysaccharide (LPS), a ubiquitous endotoxin mediator of gram-negative bacteria, alone and in combination with iron-ascorbate, on enterocyte function. Furthermore, we assessed the antioxidant capac ty of butylated hydroxytoluene (BHT) and butyric acid, which are known to play a significant role in the welfare of intestinal mucosa. Design: Differentiated intestinal Caco-2 cells were used to study the induction of membrane peroxidation by LPS (100 μg/mL) and iron-ascorbate (0.2 and 2 mmol/L, respectively) and to examine the beneficial effects of BHT and butyric acid. Results: A significant dose-dependent increase in malondialdehyde, accompanied by lower apical membrane fluidity and significantly decreased sucrase activity, was observed when Caco-2 cells were incubated with LPS. LPS also augmented paracellular permeability ([14C]polyethylene glycol flux), prostaglandin E2 production, and cyclooxygenase-2 (EC 1.14.99.1) expression. These abnormalities were exacerbated by the coadministration of iron-ascorbate, but most of them were suppressed by butyric acid and BHT. Conclusion: Bacterial endotoxin and prooxidants may overwhelm antioxidant defenses and become deleterious to enterocyte function, whereas butyric acid and BHT may provide antioxidant protection.