|1698-2||ExoU activates NF-kB in P. aeruginosa-infected human cells.|
|Autores:||Carolina Diettrich Mallet de Lima (UERJ - Universidade do Estado do Rio de Janeiro) ; Teresa Cristina Calegari-silva (UFRJ - Universidade Federal do Rio de Janeiro) ; Renata Meirelles Santos Pereira (UFRJ - Universidade Federal do Rio de Janeiro) ; Jessica da Conceição Costa (UERJ - Universidade do Estado do Rio de Janeiro) ; Ulisses Gazos Lopes (UFRJ - Universidade Federal do Rio de Janeiro) ; Maria-cristina Maciel Plotkowski (UERJ - Universidade do Estado do Rio de Janeiro) ; Alessandra Mattos Saliba (UERJ - Universidade do Estado do Rio de Janeiro) |
Among the virulence factors secreted by Pseudomonas aeruginosa type III secretion system, ExoU plays an important role in the establishment and evolution of invasive acute infections due to the proinflammatory properties of its phospholipase A2 (PLA2)-like activity. Here, we investigated the effect of ExoU on activation of NF-κB, a transcriptional factor that regulates a number of genes involved in inflammatory and immune responses. As shown by electrophoretic mobility shift assay (EMSA), ExoU induced a remarkable NF-κB nuclear translocation in P. aeruginosa-infected epithelial and endothelial cell lines, which was abrogated by Bay 11-7082 pre-treatment. A more detailed analysis by supershift revealed that infection by the ExoU-producing strain changed the p65/p50 complex into a higher mobility complex, indicating that ExoU induces nuclear translocation of this transactivator heterodimer, in both cell lines. Moreover, luciferase reporter assays showed the ability of ExoU to induce NF-κB-dependent transcriptional activity in target genes, since it was observed a significant increase of luciferase activity in epithelial cell cultures infected with the ExoU-producing P. aeruginosa strain when compared to non-infected cultures or cultures infected with the ExoU-deficient strain. In addition, Western Blot assays showed that ExoU PLA2 activity reduced IκBα levels, suggesting that ExoU activates the canonical NF-kB pathway. Our study showed that NF-κB is an important target explored by ExoU that could modulate host response by regulating a wide range of genes during P. aeruginosa infection. Regulation of NF-κB pathway could be used to control the inflammatory response and the products actively secreted by host cells or released during the ExoU-induced cell death.
Palavras-chave: Pseudomonas aeruginosa, ExoU, Type III Secretion System, Inflammation, NF-κB