ExoU contributes to late killing of Pseudomonas aeruginosa - infected endothelial cells

ABSTRACT

To ascertain the role of ExoU in late P. aeruginosa cytotoxicity, endothelial cells (EC) were exposed to wild type PA103, PA103deltaexoU and PA103exsA for 1h and to gentamicin in culture medium. After 24h, the viability of PA103-infected cells (33.7 ± 14.3%) was significantly lower than the viability of PA103deltaexoU- (77.7 ± 6.3%) or PA103exsA- (79.5 ± 23.3%) infected EC. P. aeruginosa cytotoxicity did not depend on the bacterial ability to interact with EC because the percentage of cells with associated PA103 (35.9 ± 15.8%) was similar to the percentage in PA103deltaexoU- (34.2 ± 16.0%) and lower than the percentage in PA103exsA-infected cultures (82.9 ± 18.9%). Cell treatment with cytochalasin D reduced the PA103 internalization by EC but did not interfere with its ability to kill host cells.

RESUMO

Para determinar o papel de ExoU na citotoxicidade tardia de P. aeruginosa, células endoteliais (CE) foram expostas às cepas PA103, PA103deltaxoU e PA103exsA por 1h e à gentamicina em meio de cultura. Após 24h, a viabilidade das CE infectadas com PA103 (33.7 ± 14.3%) foi inferior à de CE infectadas com PA103deltaexoU (77.7 ± 6.3%) e PA103exsA (79.5 ± 23.3%). A citotoxicidade não dependeu da capacidade de interagir com as CE porque o percentual de células com bactérias associadas em culturas expostas a PA103 foi semelhante ao percentual em culturas expostas a PA103deltaexoU e inferior em culturas expostas a PA103exsA. O tratamento das CE com citocalasina D reduziu a internalização de PA103, mas não interferiu em sua citotoxicidade.