Abstract
Abstract: :
Purpose: Alterations in the retinal pigment epithelium (RPE) resulting from bacterial infection may contribute to blood–retinal barrier permeability during Bacillus or other types of bacterial endophthalmitis. The purpose of this study was to analyze alterations in RPE tight junction and cytoskeletal proteins and the permeability of RPE in the context of Bacillus infection. Methods: Retinal pigment epithelial (ARPE–19) cells were infected with toxigenic or atoxigenic Bacillus cereus. At various times postinfection, cells were analyzed for monolayer integrity, changes in distribution of tight junction proteins ZO–1, claudin, and occludin, and changes in distribution of cytoskeletal proteins actin and tubulin by immunofluorescence and confocal microscopy. Changes in RPE monolayer permeability during infection were also analyzed by identifying changes in transepithelial resistance and permeability to FITC–labeled dextran. Results: Bacillus infection of RPE monolayers resulted in dose– and time–dependent loss of integrity and disruption of tight junctions between cells. Tight junction proteins that were localized in an apical zone around RPE cells in intact monolayers were disrupted and became disorganized throughout the cells during Bacillus infection. Nuclear condensation also occurred in addition to cytoskeletal protein disorganization. Bacillus infection of RPEs also resulted in dose– and time–dependent decreases in transepithelial resistance and increased migration of FITC–dextran through the monolayers during infection.Conclusions: Bacillus infection caused cytoskeletal protein and tight junction integrity changes in RPE cells that may lead to increased permeability. Future studies will focus on determining whether these findings extend to RPE in vivo and the blood–retinal barrier permeability observed during Bacillus and other types of bacterial endophthalmitis.
Keywords: endophthalmitis • bacterial disease • retina