Modulação da expressão de MUC1 e MUC5AC por ExoU de Pseudomonas aeruginosa

• Autor(a) principal: Monteiro, Alexandre Costa
• Data de Publicação: 2020
• Outros Autores: [e-mail]
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UERJ
• Texto Completo: http://www.bdtd.uerj.br/handle/1/18708
• topic: Pseudomonas aeruginosa; ExoU; Mucins; MUC1; Pseudomonas aeruginosa; ExoU; Mucinas; MUC1; MUC5AC; CIENCIAS BIOLOGICAS::MICROBIOLOGIA::MICROBIOLOGIA APLICADA::MICROBIOLOGIA MEDICA

ExoU is a cytotoxin that induces a potent activation of the inflammatory response and interferes with the host intracellular signaling pathways, altering the innate immune response. ExoU-producing strains of Pseudomonas aeruginosa are associated with a worse infection prognosis and higher lethality. Mucins are glycoproteins expressed in mucous membranes, where they provide protection against pathogenic bacteria. MUC1 is a transmembrane mucin with an immunomodulatory role during bacterial infections, whereas MUC5AC is one of the main mucins expressed in the respiratory mucus, considered the first airway barrier against several infectious agents. This work investigated the role of ExoU on the modulation of MUC1 and MUC5AC expression during the infection by P. aeruginosa as well as the impact of this modulation on the host response. For this purpose, A549 adenocarcinomic human alveolar epithelial cells were infected with the parental strain PA103 (ExoU-producer), or with its mutants PA103ΔexoU (ExoU non-producer) and PA103/S142A (complemented with ExoU without phospholipase A2 activity). Additionally, the mRNA expression of Muc1 and Muc5AC was evaluated in the lungs of C57BL/6 mice infected with PA103 or PA103ΔexoU. In our results, ExoU inhibited the MUC1 expression in airway epithelial cells infected with PA103. However, PA103ΔexoU-infected cells showed activation of MUC1 expression in a JNK-dependent manner. These results were supported by the animal model, as lungs from PA103-infected mice exhibited lower Muc1 mRNA levels compared to PA103ΔexoU-infected mice. Interestingly, ExoU induced MUC1 nuclear translocation, which is involved in the regulation of the antioxidant and inflammatory responses. Cell treatment with an inhibitor of the MUC1-mediated intracellular signaling, GO-201, showed that MUC1 attenuates the intracellular levels of reactive oxygen species (ROS), regardless of ExoU. More importantly, GO-201 reduced the secretion of CXCL8 in PA103-infected cells, indicating that the nuclear translocation of MUC1 upregulates CXCL8 secretion. Concerning MUC5AC, 1 hour after infection, cells infected with PA103 showed higher levels of mRNA and lower levels of intracellular protein compared to those infected with the mutant strains. There was no significant difference in Muc5ac mRNA expression when mice infected by PA103 were compared to those infected by PA103ΔexoU. In conclusion, this study showed that ExoU inhibits MUC1 expression and promotes its nuclear translocation during infection by P. aeruginosa. Also, the nuclear translocation of MUC1, induced by ExoU, contributes to the activation of CXCL8 expression. Although ExoU has been able to modulate the MUC5AC expression in the in vitro assays, this result was not corroborated by the in vivo model.