Cytoskeleton as a target for injury in damaged intestinal epithelium

This report summarizes the findings of a series of studies undertaken to discern the role of the cytoskeleton in intestinal injury and defense. Two established cell lines were used for these studies. IEC-6 cells (a rat intestinal cell line) were incubated in Eagle's minimal essential medium with and without 16, 16 dimethyl prostaglandin E(2) (dmPGE(2); 2.6 microM) for 15 minutes and subsequently incubated in medium containing 10% ethanol (EtOH). The effects on cell viability and the actin cytoskeleton were then determined. Using a similar protocol, Caco-2 cells (a human colonic cell line) were employed to assess the microtubule cytoskeleton under these conditions. In both cell lines, EtOH extensively disrupted the cytoskeletal component being evaluated coincident with adversely affecting cell viability. Pretreatment with dmPGE(2) increased cell viability and abolished the disruptive effects on both the actin and microtubule cytoskeleton in cells exposed to EtOH. Prior incubation with cytochalasin D, an actin disruptive agent, prevented the protective capabilities of dmPGE(2) in IEC-6 cells challenged with EtOH. Phalloidin, an actin stabilizing agent, demonstrated similar effects to that of dmPGE(2) by stabilizing the actin cytoskeleton and preserving cellular viability in IEC-6 cells in response to EtOH. In Caco-2 cells, taxol, a microtubule stabilizing agent, mimicked the effects of dmPGE(2) by increasing cell viability in cells exposed to EtOH and enhancing microtubular integrity. In contrast, pretreatment with colchicine, an inhibitor of microtubule integrity, prevented the protective effects of dmPGE(2). These findings support the hypothesis that the cytoskeleton may be a major target for injury in damaged intestinal epithelium, and that the protective action of dmPGE(2) is orchestrated through preservation of this target.