PSEUDOMONAS-AERUGINOSA ADHESION TO NORMAL AND INJURED RESPIRATORY MUCOSA

Human nasal polyps in outgrowth culture were used to study the adhesio n of Pseudomonas aeruginosa to respiratory cells. By transmission elec tron microscopy, bacteria associated with ciliated cells were identifi ed trapped at the extremities of cilia, usually as aggregates of sever al bacterial cells. They were never seen at the interciliary spaces or attached along cilia. Bacteria were also seen to adhere avidly to mig rating cells of the periphery of the outgrowth culture. Using a model of repair of wounded respiratory epithelial cells in culture, we obser ved 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 f ibronectin-containing fibrillar material. The secretion of extracellul ar matrix components is involved in the process of epithelium repair f ollowing injury. To investigate the molecular basis of P. aeruginosa a dhesion to migrating cells, bacteria were treated with a fibronectin s olution before their incubation with the respiratory cells. P. aerugin osa treatment by fibronectin significantly increased their adhesion to migrating cells. Accordingly, we hypothesize that during cell migrati on, fibronectin secreted by epithelial cells may favour P. aeruginosa adhesion by establishing a bridge between the bacteria and the epithel ial cell receptors. Such a mechanism may represent a critical step for P. aeruginosa infection of healing injured epithelium.