Pseudomonas aeruginosa Induces Interferon-ß Production to Promote Intracellular Survival.

Pseudomonas aeruginosa (PA) is known as one kind of extracellular pathogens. However, more evidence showed that PA encounters the intracellular environment in different mammalian cell types. Little is known of innate immune factors modulating intracellular PA survival. In the present study, we proposed that interferon-ß (IFN-ß) is beneficial to the survival of PA in the cytoplasm of macrophages. Furthermore, we found that interleukin-1ß (IL-1ß) induced by PA suppresses IFN-ß response driven by the cGAS-STING-TBK1 pathway. Mechanistically, IL-1ß decreased the production of cyclic GMP-AMP (cGAMP) by activating AKT kinase. cGAMP is necessarily sufficient to stimulate the transcription of IFN-ß via the STING adaptor-TBK1 kinase-IRF3 transcription factor axis. Thus, our findings uncovered a novel module for PA intracellular survival involving IFN-ß production restricted by IL-1ß and provided a strong rationale for a potential clinical strategy against pulmonary PA infection patients. IMPORTANCE The link between innate immunity and intracellular Pseudomonas aeruginosa is unclear. Our studies illuminated the role of interferon-ß (IFN-ß) in remote intracellular PA infection. Furthermore, our experimental evidence also indicated that IL-1ß is a negative regulator of IFN-ß production and, in particular, P. aeruginosa infection. The inhibition of IFN-ß may be used as a potential therapeutic method against pulmonary PA infection.

Airway acidification impaired host defense against Pseudomonas aeruginosa infection by promoting type 1 interferon ß response.

Airway microenvironment played an important role in the progression of chronic respiratory disease. Here we showed that standardized pondus hydrogenii (pH) of exhaled breath condensate (EBC) of bronchiectasis patients was significantly lower than that of controls and was significantly correlated with bronchiectasis severity index (BSI) scores and disease prognosis. EBC pH was lower in severe patients than that in mild and moderate patients. Besides, acidic microenvironment deteriorated Pseudomonas aeruginosa (P. aeruginosa) pulmonary infection in mice models. Mechanistically, acidic microenvironment increased P. aeruginosa outer membrane vesicles (PA_OMVs) released and boosted it induced the activation of interferon regulatory factor3 (IRF3)-interferonß (IFN-ß) signalling pathway, ultimately compromised the anti-bacteria immunity. Targeted knockout of IRF3 or type 1 interferon receptor (IFNAR1) alleviated lung damage and lethality of mice after P. aeruginosa infection that aggravated by acidic microenvironment. Together, these findings identified airway acidification impaired host resistance to P. aeruginosa infection by enhancing it induced the activation of IRF3-IFN-ß signalling pathway. Standardized EBC pH may be a useful biomarker of disease severity and a potential therapeutic target for the refractory P. aeruginosa infection. The study also provided one more reference parameter for drug selection and new drug discovery for bronchiectasis.