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Effect of Pseudomonas aeruginosa rhamnolipids on mucociliary transport and ciliary beating
1Department of Thoracic Medicine, National Heart and Lung Institute, London, United Kingdom.
Abstract:
Pseudomonas aeruginosa rhamnolipid causes ciliostasis and cell membrane damage to rabbit tissue, is a secretagogue in cats, and inhibits epithelial ion transport in sheep tissue. It could therefore perturb mucociliary clearance. We have investigated the effect of rhamnolipid on mucociliary transport in the anesthetized guinea pig and guinea pig and human respiratory epithelium in vitro. Application of rhamnolipid to the guinea pig tracheal mucosa reduced tracheal mucus velocity (TMV) in vivo in a dose-dependent manner: a 10-microgram bolus caused cessation of TMV without recovery; a 5-micrograms bolus reduced TMV over a period of 2 h by 22.6% (P = 0.037); a 2.5-microgram bolus caused no overall changes in TMV. The ultrastructure of guinea pig tracheal epithelium exposed to 10 micrograms of rhamnolipid in vivo was normal. Application of 1,000 micrograms/ml rhamnolipid had no effect on the ciliary beat frequency (CBF) of guinea pig tracheal rings in vitro after 30 min, but 250 micrograms/ml stopped ciliary beating after 3 h. Treatment with 100 micrograms/ml rhamnolipid caused immediate slowing of the CBF (P less than 0.01) of human nasal brushings (n = 7), which was maintained for 4 h. Mono- and dirhamnolipid had equivalent effects. The CBF of human nasal turbinate organ culture was also slowed by 100 micrograms/ml rhamnolipid, but only after 4 h (CBF test, 9.87 +/- 0.41 Hz; control, 11.48 +/- 0.27 Hz; P less than 0.05, n = 6), and there was subsequent recovery by 14 h.(ABSTRACT TRUNCATED AT 250 WORDS)
Insights
Pseudomonas aeruginosa rhamnolipid impairs mucociliary clearance by reducing tracheal mucus velocity and ciliary beat frequency in animal and human respiratory tissues. This bacterial toxin could disrupt lung defense mechanisms.
Area of Science:
- Microbiology
- Pulmonology
- Toxicology
Background:
- Pseudomonas aeruginosa rhamnolipid is known to damage various tissues and affect physiological processes.
- Its potential to disrupt mucociliary clearance, a critical lung defense mechanism, requires investigation.
Purpose of the Study:
- To investigate the effect of rhamnolipid on mucociliary transport in guinea pigs and human respiratory epithelium.
- To determine the dose-dependent effects of rhamnolipid on tracheal mucus velocity and ciliary beat frequency.
Main Methods:
- In vivo studies using anesthetized guinea pigs to measure tracheal mucus velocity (TMV) after rhamnolipid application.
- In vitro studies using guinea pig tracheal rings and human nasal brushings/organ cultures to assess ciliary beat frequency (CBF).
Main Results:
- Rhamnolipid reduced TMV in guinea pigs in a dose-dependent manner, with higher doses causing cessation.
- In vitro, rhamnolipid slowed or stopped ciliary beating in both guinea pig and human respiratory tissues, with varying onset and duration.
- Mono- and dirhamnolipid showed equivalent effects on ciliary beat frequency.
Conclusions:
- Pseudomonas aeruginosa rhamnolipid significantly impairs mucociliary clearance by affecting both mucus transport and ciliary function.
- These findings suggest rhamnolipid can compromise respiratory tract defenses, potentially increasing susceptibility to infections.