Oxidants increase paracellular permeability in a cultured epithelial cell line.

Abstract

Inflammation of epithelia is an important step in the pathophysiology of a wide variety of diseases. Because reactive oxygen metabolites are important effector molecules of acute inflammation, we examined the effect of oxidants on the barrier function of a cultured epithelium, Madin Darby Canine Kidney cells, by measuring the transepithelial electrical conductance, Gt, of monolayers grown on permeable supports. We found that H202, added directly or generated with glucose oxidase, increased G,. Similar effects were observed with addition of xanthine and xanthine oxidase, a system which enzymatically generates superoxide radical O2. The oxidant-induced increase in G, was reversible if the exposure to oxidants was not prolonged (<20 min), and if the concentration of H202 was <5 X 10-3 M. The increase in G, suggested that oxidants increase the permeability ofthe paracellular pathway, a suggestion supported by an oxidant-induced increase in the permeability to '4C-mannitol, which primarily crosses epithelia via the extracellular route.In addition to functional changes in the epithelial monolayer, oxidants changed the cell morphology-, after H202 exposure, the cells tended to pull apart, most prominently at their basolateral surfaces. These changes were heterogeneous with most areas showing no changes. Some of the morphologic changes could be reversed if the exposure to H202 was limited. We also observed a disruption of the normal pattern of the actin-cytoskeleton, particularly in the area of cell to cell junctions, as demonstrated by fluorescent staining of f-actin with rhodamine phallicidin.These functional and structural findings indicate that oxidants increase the permeability of the paracellular pathway in a cultured epithelium. The changes can be reversible, and are accompanied by alterations in organization of the cell cytoskeleton. These studies demonstrate the dynamic nature of the interaction between epithelial cells and oxygen metabolites.

Bacterial translocation in an experimental intestinal obstruction model: C-reactive protein reliability?

“…Likely to the disturbed dynamic milieu of the intestinal tract during intestinal obstruction, this study defined bacterial overgrowth association with I.O in line with Akin et al 15 and Sagar et al 16 , also the oxidative stress pattern during I.O produce ATP depletion 17 , cytoskeleton disruption 18,19 , neutrophil priming 20 resulting in mechanical gut barrier dysfunction, and significantly the I.O association with impaired IL-10 response as reported by Zingarelli et al 21 and Souza et al 22 declare the immune incompetence status. Although O'Boyle 23 deny those associations.…”

Mechanism of Resistance to Oxidative Stress in Doxorubicin Resistant Cells.

“…Hydrogen peroxide is known to convert quickly into hydroxyl radicals in cells, and it has cytotoxic activity which results from DNA damage, lipid peroxidation and biochemical perturbations such as cytoplasmic changes and gross perturbation of the cytoskeleton and plasma membrane in cells. 37,38) Exogenous superoxide dismutase, catalase, and hydroxyl radical scavengers were shown to partially protect tumor cells from DOX cytotoxicity.…”

Reassembly of the Tight Junction after Oxidative Stress Depends on Tyrosine Kinase Activity

“…Reported effects of hydrogen peroxide on renal epithelial cell lines include DNA damage with induction of apoptosis or necrosis (1-3), decreased activity of membrane transporters (4), and membrane lipid peroxidation (5). Hydrogen peroxide decreases transepithelial resistance (TER) and increases transcellular permeability of MDCK cell monolayers (6,7), which is also well documented in non-kidney epithelial cell lines (8 -11) and endothelial cell lines (12)(13)(14)(15). However, the biochemical and subcellular effects of hydrogen peroxide on tight junction (TJ) proteins have not been studied, nor have they been distinguished from effects due to partial ATP depletion.…”