Nitric oxide attenuates hydrogen peroxide-induced barrier disruption and protein tyrosine phosphorylation in monolayers of intestinal epithelial cell

Abstract

The intestinal epithelium provides a barrier to the transport of harmful luminal molecules into the systemic circulation. A dysfunctional epithelial barrier is closely associated with the pathogenesis of a variety of intestinal and systemic disorders. We investigated here the effects of nitric oxide (NO) and hydrogen peroxide (H(2)O(2)) on the barrier function of a human intestinal epithelial cell line, Caco-2. When treated with H(2)O(2), Caco-2 cell monolayers grown on permeable supports exhibited several remarkable features of barrier dysfunction as follows: a decrease in transepithelial electrical resistance, an increase in paracellular permeability to dextran, and a disruption of the intercellular junctional localization of the scaffolding protein ZO-1. In addition, an induction of tyrosine phosphorylation of numerous cellular proteins including ZO-1, E-cadherin, and beta-catenin, components of tight and adherens junctions, was observed. On the other hand, combined treatment of Caco-2 monolayers with H(2)O(2) and an NO donor (NOC5 or NOC12) relieved the damage to the barrier function and suppressed the protein tyrosine phosphorylation induced by H(2)O(2) alone. These results suggest that NO protects the barrier function of intestinal epithelia from oxidative stress by modulating some intracellular signaling pathways of protein tyrosine phosphorylation in epithelial cells.

Nitric oxide and airway epithelial barrier function: Regulation of tight junction proteins and epithelial permeability

“…In the next set of studies, we determined whether epithelial NO • may protect against oxidant-induced barrier function, as suggested previously [16, 18]. To this end, we pre-incubated MTE cells from WT or NOS2-/- mice with LPS for 24 hrs, to induce NOS2 expression (Fig.…”

“…Contrary to claims that NO • can contribute to epithelial barrier disruption during inflammation, several studies have suggested that NO • may protect barrier function during infection or oxidative stress [16–19]. To determine whether NO • is capable of promoting restoration of disrupted barrier function, we incubated 16HBE14o- cells in MEM without FBS and supplemented with 2 mM EGTA, which results in TJ disruption [26], and followed TER restitution after replacing the EGTA medium with normal Ca 2+ -containing medium in the absence or presence of DETA-NO.…”

“…For example, pulmonary edema during in vivo endotoxemia was reported to depend in part on NOS2, and in vitro studies with the airway epithelial cell line Calu-3 implicated NOS2 in cytokine-induced epithelial permeability [12]. However, others failed to demonstrate involvement of NOS2-derived NO • in epithelial injury during inflammation [14, 15], and several studies suggested that NOS2 may in fact be protective against epithelial injury during oxidative stress or bacterial infection [16–19]. For example, apical stimulation of isolated rat alveolar type II cells with LPS enhanced epithelial resistance to oxidative stress, which was dependent on induction of NOS2 and elevated NO • production [18].…”

Nitric Oxide Decreases the Permselectivity of the Paracellular Pathway in Thick Ascending Limbs

“…In epithelial cells of the gastrointestinal tract, NO has been shown to both increase and decrease permeability 20-23, 41-45 . The precise explanation for these data is unclear; however it may be related to the source of the NO, and therefore its concentration.…”

Cell-Cell Junctions and Vascular Endothelial Growth Factor in Rat Lung as Affected by Ischemia/Reperfusion and Preconditioning With Inhaled Nitric Oxide

“…These effects are not restricted to lung tissue, since Failor et al [42] recently reported glucocorticoid-dependent down-regulation of GSK-3b, which altered cellular b-catenin phosphorylation, leading to localization of b-catenin to the cell periphery, formation of AJs, and tight junction sealing in mammary epithelial tumor cells. The role of NO in this context has rarely been investigated, and contradictory results of experiments using cellular systems and NO donors have been reported [43,44].…”