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Clearance of Pseudomonas aeruginosa in different rat lung models
1Hygiene-Institut, University of Tübingen, Federal Republic of Germany.
Abstract:
Chronic pulmonary infections with Pseudomonas aeruginosa remain a serious problem in patients with cystic fibrosis. Structurally altered lung mucosa and local inflammation may impair bacterial clearance from the airways. This hypothesis was investigated in (1) the reserpinized rat, (2) proteinase-pretreated rat lungs, and (3) Type III hypersensitivity rat lung models. Reserpine treatment led to surface alterations of Type I epithelial lung cells and diminished food uptake. Significantly enhanced P. aeruginosa colony-forming units (CFU) were found in all (12 of 12) rat lungs 48 h after challenge compared to partially starved rats (p less than 0.025) or untreated rats (p less than 10(-6)). Pretreatment of normal rat lungs with elastase from polymorphonuclear leukocytes (PMN-elastase) resulted in extensive tissue damage, and 48 h after bacterial challenge the mean P. aeruginosa CFU of 12 animals was significantly higher 1.1 X 10(4) +/- 1.0 X 10(4) CFU; p less than 0.01) than in the reserpinized rat lungs. P. aeruginosa organisms were also found in PMN-elastase-treated rat lungs not challenged with bacteria (five of 12 animals), suggesting cross infection from infected animals in the same cage. In immunized rats that were challenged with aerosolized antigen (bovine serum albumin) and P. aeruginosa, bacterial CFU after 10 h were significantly higher than in nonimmune animals (p less than 0.005), and highest after 48 h when P. aeruginosa alkaline proteinase was used as the antigen (1.2 X 10(5) +/- 1.4 X 10(5) CFU). These data provide new evidence that clearance of P. aeruginosa from lung tissue is impaired after malnutrition, epithelial cell alteration, or epithelial cell damage.(ABSTRACT TRUNCATED AT 250 WORDS)
Insights
Pseudomonas aeruginosa lung infections are worsened by malnutrition and lung tissue damage, impairing bacterial clearance in cystic fibrosis patients. These conditions significantly increase bacterial load in rat models.
Area of Science:
- Pulmonary Medicine
- Microbiology
- Immunology
Background:
- Chronic Pseudomonas aeruginosa infections are a significant challenge in cystic fibrosis patients.
- Impaired bacterial clearance from airways may result from altered lung mucosa and inflammation.
Purpose of the Study:
- To investigate how malnutrition, epithelial cell alteration, and inflammation affect Pseudomonas aeruginosa clearance in rat lung models.
Main Methods:
- Utilized reserpinized rats, proteinase-pretreated rat lungs, and Type III hypersensitivity rat lung models.
- Assessed Pseudomonas aeruginosa colony-forming units (CFU) in rat lungs 48 hours post-challenge.
Main Results:
- Reserpine treatment (malnutrition model) significantly increased P. aeruginosa CFU compared to controls.
- PMN-elastase pretreatment (tissue damage model) led to higher bacterial CFU and suggested cross-contamination.
- Immunized rats showed significantly higher bacterial CFU, especially when challenged with P. aeruginosa alkaline proteinase.
Conclusions:
- Lung tissue damage, malnutrition, and inflammation impair the clearance of Pseudomonas aeruginosa.
- These findings highlight mechanisms contributing to persistent lung infections in cystic fibrosis.