Dataset Information

Response to acute lung infection with mucoid Pseudomonas aeruginosa in cystic fibrosis mice.

ABSTRACT:

Rationale

Cystic fibrosis is caused by defects in the cystic fibrosis transmembrane conductance regulator gene, which codes for a chloride channel, but the role of this chloride channel in inflammation induced by lung infection with Pseudomonas aeruginosa remains to be defined.

Objectives

We tested the hypothesis that loss of this chloride channel alone is sufficient to cause excessive inflammation in response to inflammatory stimuli.

Methods

We investigated the response of cystic fibrosis and wild-type mice to mucoid P. aeruginosa administered by insufflation.

Measurements

The host responses measured included survival, weight change, lung morphometry, bacterial clearance, and inflammatory mediators, and cell counts were assessed in bronchoalveolar lavage fluid.

Main results

Depending on the dose administered and frequency of dosing, cystic fibrosis mice experienced significantly higher mortality rates, greater weight loss, higher lung pathology scores, and higher inflammatory mediator and neutrophil levels compared with wild-type mice, even after the bacteria had been cleared. Surprisingly, bacteria were cleared just as rapidly in cystic fibrosis mice as in wild-type mice, and sepsis was not observed. Chronic lung infections could not be established with mucoid P. aeruginosa in either cystic fibrosis or wild-type mice.

Conclusions

Absence of this chloride channel alone appears sufficient for exaggerated inflammation and excess mortality compared with wild-type controls in the face of mucoid P. aeruginosa lung infection. To establish chronic infection, additional factors such as bacterial trapping or poor clearance may be required.

SUBMITTER: van Heeckeren AM

PROVIDER: S-EPMC2662931 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BACKGROUND: Since the discovery of the human CFTR gene in 1989 various mouse models for cystic fibrosis (CF) have been generated and used as a very suitable and popular tool to approach research on this life-threatening disease. Age related changes regarding the course of disease and susceptibility towards pulmonary infections have been discussed in numerous studies. METHODS: Here, we investigated CftrTgH(neoim)Hgu and Cftrtm1Unc-Tg(FABPCFTR)1Jaw/J CF mice and their non-CF littermates during an acute lung infection with Pseudomonas aeruginosa for age dependent effects of their lung function and immune response.Mice younger than three or older than six months were intratracheally infected with P. aeruginosa TBCF10839. The infection was monitored by lung function of the animals using non-invasive head-out spirometry and the time course of physiological parameters over 192 hours. Quantitative bacteriology and lung histopathology of a subgroup of animals were used as endpoint parameters. RESULTS: Age-dependent changes in lung function and characteristic features for CF like a shallower, faster breathing pattern were observed in both CF mouse models in uninfected state. In contrast infected CF mice did not significantly differ from their non-CF littermates in susceptibility and severity of lung infection in both mouse models and age groups. The transgenic Cftrtm1Unc-Tg(FABPCFTR)1Jaw/J and their non-CF littermates showed a milder course of infection than the CftrTgH(neoim)Hgu CF and their congenic C57Bl/6J non-CF mice suggesting that the genetic background was more important for outcome than Cftr dysfunction. CONCLUSIONS: Previous investigations of the same mouse lines have shown a higher airway susceptibility of older CF mice to intranasally applied P. aeruginosa. The different outcome of intranasal and intratracheal instillation of bacteria implies that infected CF epithelium is impaired during the initial colonization of upper airways, but not in the subsequent response of host defense.