Related Experiment Videos
Cystic fibrosis, lung infections, and a human tracheal antimicrobial peptide (hTAP)
Y H Ko1, M Delannoy, P L Pedersen
1Department of Biological Chemistry, Johns Hopkins University, School of Medicine, Baltimore, MD 21205-2185, USA.
Insights
Healthy lungs defend against Pseudomonas aeruginosa infection, unlike cystic fibrosis (CF) lungs. A protective peptide (hTAP) in healthy tracheal cells may fail in CF, allowing bacterial growth and entry.
Area of Science:
- Pulmonary Medicine
- Microbiology
- Cell Biology
Background:
- Cystic Fibrosis (CF) patients exhibit increased susceptibility to bacterial lung infections, particularly Pseudomonas aeruginosa.
- The mechanisms underlying the differential protection of healthy versus CF lungs against bacterial pathogens remain incompletely understood.
Purpose of the Study:
- To elucidate the cellular and molecular differences in host defense against Pseudomonas aeruginosa between healthy individuals and cystic fibrosis patients.
- To investigate the role of human tracheal epithelial peptide (hTAP) in protecting against bacterial infection.
Main Methods:
- Comparative analysis of Pseudomonas aeruginosa growth on primary human tracheal epithelial cells from healthy donors and CF patients (deltaF508 mutation).
- Assessment of bacterial adherence and invasion into epithelial cells under physiological salt conditions.
- Identification and characterization of bactericidal peptides expressed by human tracheal epithelial cells.
Main Results:
- Pseudomonas aeruginosa exhibited limited multiplication on healthy human tracheal epithelial cells but proliferated extensively on cells from deltaF508 CF patients.
- Bacterial adherence and invasion into CF tracheal epithelial cells occurred even at physiological salt concentrations (104 mM).
- Human tracheal epithelial cells express a bactericidal peptide, human tracheal antimicrobial peptide (hTAP), effective against Pseudomonas aeruginosa.
Conclusions:
- Healthy tracheal epithelial cells possess a self-defense mechanism involving hTAP that inhibits Pseudomonas aeruginosa proliferation.
- This protective mechanism appears compromised in cystic fibrosis, potentially due to altered hTAP function or expression, leading to increased susceptibility to infection.
- A model is proposed where the failure of this innate defense contributes to the pathogenesis of CF lung disease.
Abstract:
In order to understand how lungs of healthy people, unlike those of cystic fibrosis (CF) patients, are protected against bacterial infections such as Pseudomonas aeruginosa, the following three key findings were made. First, P. aeruginosa do not multiply when planted onto tracheal epithelial cells from healthy humans but do so profusely on cells from deltaF508 CF patients. Second, some bacteria bind, and gain entrance into CF cells, even at a physiological salt concentration (104 mM). Third, human tracheal epithelial cells express an approximately 4 kDa peptide (hTAP), which is known in its bovine form to exhibit bactericidal action against P. aeruginosa. A model is proposed depicting both how normal epithelial cells, in a first-line self defense mechanism, may be protected against bacterial infection and how this mechanism may fail during the initial stages of CF.