Protective effects of captopril on oxidative strees-induced disruption of tight junction structure and function in ECV304 cells

Abstract

The objective of this study was to investigate the protective effects of captopril on oxidative stress-induced hyperpermeability of epithelial barriers, using the in vitro model of ECV304 cell monolayers grown for either 2 days or 12 days after seeding. Treatment the monolayers with H2O2 (200 µM for 4 h) had no effects on cell viability as measured by MTT assay. In 12 days after seeding, the ECV304 monolayers developed high transepithelial electrical resistance (TEER) value and restrictiveness against paracellular movement of phenol red, suggesting the formation of tight junction complexes. Exposure to H2O2 resulted in reduction of TEER and phenol red hyperpermeability. In addition, immunofluorescence visualization indicated the disruptive pattern of occludin and ZO-1 at the cell borders. However, the amount of occludin and ZO-1 proteins remained normal with the western blot analysis. In 2 days after seeding, the barrier function of ECV304 was not fully developed. Treatment of H2O2 during this period caused disruptive pattern of immunofluorescence staining of occludin and ZO-1 along with the decreased amount of occludin protein. Pretreatment the monolayers with captopril (100 µM for 30 min) prior to H2O2 could preserve the barrier restrictive functions. Regardless of the period, captopril was able to abolish the oxidative damages on localization and amount of tight junction proteins. The results also suggested the involvement of ERK1/2 pathway in tight junction stability.