Subversion of the airway host cell machinery during non-typable Haemophilus influenzae infection: molecular mechanisms and clinical implications

Autor: López-Gómez, Antonio, Cano, Victoria, Martí-Lliteras, Pau, Morey, Pau, Bengoechea, José Antonio, Garmendia, Juncal
Rok vydání: 2011
Zdroj: Digital.CSIC. Repositorio Institucional del CSIC
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Popis: Trabajo presentado en la International Pasteurellaceae Conference, celebrada en Elsinore (Dinamarca) del 24 al 27 de agosto de 2011.
[Aim] Nontypable Haemophilus influenzae (NTHi) causes acute respiratory infections and is responsible for the progression of chronic respiratory diseases. NTHi interaction with the human respiratory epithelium involves adhesion, invasion and non-replicative intracellular location. We carried out a molecular dissection of multiple host signaling pathways subverted by NTHi during epithelial invasion.
[Methods] Human type II pneumocytes and NTHi375 clinical isolate were used to carry out adhesion and invasion assays, processed by bacterial quantification; microscopy; electrophoretic separation and immunodetection by western blot. Deciphering of host cell pathways involved in NTHi invasion was assessed by specific chemical inhibitors, transfection with dominant negative variants, and host cell gene interference by siRNA.
[Results and Conclusions] NTHi invasion occurs by interaction with host cell surface integrins and subsequent activation of tyrosine kinases from the Src family. These events may happen in cholesterol-rich lipid rafts, given that their proper assembly is required for bacterial entry. PI3K signaling involved in bacterial invasion, assessed by PI3K disruption and Akt phosphorylation, seems to be connected to the activation of Src kinases, to protein kinase A and to Rac-1 GTPase. Activation of Rac-1 and its effector PAK are required for bacterial invasion. Differently, the blockage of RhoA GTPase, of its effector ROCK, and of a correct actin polymerization increase bacterial invasion. Opposite phenotypes observed by inactivation of PAK and ROCK may account for the requirement of the correct polymerization of microtubules upon NTHi invasion.The increase of eukaryotic cAMP reduces bacterial entry, which may have clinical implications.
Databáze: OpenAIRE
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