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Pseudomonas aeruginosa adhesion to normal and injured respiratory mucosa
M C Plotkowski1, J M Zahm, J M Tournier
1Serviço de Microbiologia e Immunologia, UER, Brasil.
Abstract:
Human nasal polyps in outgrowth culture were used to study the adhesion of Pseudomonas aeruginosa to respiratory cells. By transmission electron microscopy, bacteria associated with ciliated cells were identified trapped at the extremities of cilia, usually as aggregates of several bacterial cells. They were never seen at the interciliary spaces or attached along cilia. Bacteria were also seen to adhere avidly to migrating cells of the periphery of the outgrowth culture. Using a model of repair of wounded respiratory epithelial cells in culture, we observed that the adhesion of P. aeruginosa to migrating cells of the edges of the repairing wounds was significantly higher than the adhesion to non-migrating cells and that adherent bacteria were surrounded by a fibronectin-containing fibrillar material. The secretion of extracellular matrix components is involved in the process of epithelium repair following injury. To investigate the molecular basis of P. aeruginosa adhesion to migrating cells, bacteria were treated with a fibronectin solution before their incubation with the respiratory cells. P. aeruginosa treatment by fibronectin significantly increased their adhesion to migrating cells. Accordingly, we hypothesize that during cell migration, fibronectin secreted by epithelial cells may favour P. aeruginosa adhesion by establishing a bridge between the bacteria and the epithelial cell receptors. Such a mechanism may represent a critical step for P. aeruginosa infection of healing injured epithelium.
Insights
Pseudomonas aeruginosa adheres to migrating respiratory cells, particularly at wound edges. Fibronectin bridges bacteria to cells, enhancing adhesion during epithelial repair and potentially aiding infection.
Area of Science:
- Microbiology
- Cell Biology
- Respiratory Medicine
Background:
- Pseudomonas aeruginosa is a significant pathogen in respiratory infections.
- Epithelial cell repair involves migration and extracellular matrix secretion.
- Bacterial adhesion to host cells is crucial for infection establishment.
Purpose of the Study:
- To investigate the adhesion patterns of Pseudomonas aeruginosa to human respiratory cells in vitro.
- To elucidate the role of fibronectin in P. aeruginosa adhesion to migrating epithelial cells during wound repair.
Main Methods:
- Utilized human nasal polyps in outgrowth culture.
- Employed transmission electron microscopy to visualize bacterial-cell interactions.
- Developed a model for studying the repair of wounded respiratory epithelial cells.
- Assessed the effect of fibronectin pre-treatment on bacterial adhesion.
Main Results:
- P. aeruginosa preferentially adhered to the extremities of cilia and to migrating epithelial cells.
- Adhesion was significantly higher on migrating cells at wound edges compared to non-migrating cells.
- Adherent bacteria were associated with fibronectin-containing fibrillar material.
- Pre-treatment of P. aeruginosa with fibronectin enhanced its adhesion to migrating cells.
Conclusions:
- Fibronectin secreted during epithelial repair may act as a bridge, facilitating P. aeruginosa adhesion to migrating cells.
- This fibronectin-mediated adhesion mechanism could be critical for P. aeruginosa infections of healing respiratory epithelium.