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Interaction of Pseudomonas aeruginosa with human respiratory mucosa in vitro
K W Tsang1, A Rutman, E Tanaka
1Host Defence Unit, Royal Brompton National Heart & Lung Institute, London, UK.
Abstract:
Pseudomonas aeruginosa commonly infects the airways of patients with cystic fibrosis and bronchiectasis. It produces several toxins that slow ciliary beat, stimulate mucus production and damage epithelium. It adheres to epithelial cells, damaged mucosa (in animal models), and mucus. However, little is known of the interaction of P. aeruginosa with intact human respiratory mucosa. We have studied the interactions of a nonmucoid clinical isolate of P. aeruginosa with adenoid tissue in a novel organ culture model with an air-mucosal interphase P. aeruginosa (5.9 +/- 0.9 x 10(6) colony-forming units (cfu)) was pipetted onto the organ culture surface, and incubated for 15 min, 1, 2, 4, 8, 12, 16, and 24 h, at 37 degrees C in 5% CO2 in a humidified atmosphere. Assessment has been made by transmission and scanning electron microscopy. Transmission electron microscopy (TEM) showed that uninfected organ cultures had normal ultrastructure. TEM of infected organ cultures at 8 h showed significant epithelial damage: 43.9 +/- 10% of cells extruding from the epithelial surface, 17.7 +/- 3% of cells with loss of cilia, 32.9 +/- 10.2% of cells with mitochondrial damage, and 11.6 +/- 3% of cells with cytoplasmic blebbing. P. aeruginosa only infrequently adhered to normal epithelium, but adhered to areas of epithelial damage and to basement membrane. Scanning electron microscopy (SEM) of organ cultures up to 2 h found P. aeruginosa only infrequently associated with mucus. SEM at 4 h revealed P. aeruginosa predominantly associated with mucus and extruded damaged epithelial cells, but also occasionally associated with cilia, and very occasionally with unciliated cells.(ABSTRACT TRUNCATED AT 250 WORDS)
Insights
Pseudomonas aeruginosa infection damages respiratory epithelium, with bacteria adhering to damaged areas rather than intact cells. This study used organ cultures to observe bacterial interactions with human airway tissue.
Area of Science:
- Microbiology
- Cell Biology
- Respiratory Medicine
Background:
- Pseudomonas aeruginosa is a common pathogen in cystic fibrosis and bronchiectasis.
- P. aeruginosa toxins impair airway function by affecting cilia, mucus, and epithelial cells.
- Limited data exists on P. aeruginosa interactions with intact human respiratory mucosa.
Purpose of the Study:
- To investigate the interaction of P. aeruginosa with intact human respiratory mucosa using an organ culture model.
- To characterize the adherence patterns and epithelial damage caused by P. aeruginosa.
Main Methods:
- Utilized a novel organ culture model with an air-mucosal interface using human adenoid tissue.
- Inoculated tissue with P. aeruginosa (5.9 x 10^6 cfu) and incubated for up to 24 hours.
- Assessed interactions using transmission electron microscopy (TEM) and scanning electron microscopy (SEM).
Main Results:
- TEM revealed significant epithelial damage by 8 hours, including cell extrusion, cilia loss, and mitochondrial damage.
- P. aeruginosa infrequently adhered to normal epithelium but readily adhered to damaged areas and basement membrane.
- SEM showed P. aeruginosa initially associated with mucus, later found with damaged cells and occasionally cilia.
Conclusions:
- P. aeruginosa primarily adheres to damaged respiratory epithelium and basement membrane, not intact cells.
- The study provides insights into early P. aeruginosa pathogenesis in the human airway.
- The organ culture model is effective for studying host-pathogen interactions in respiratory tissues.