Pseudomonas aeruginosa adherence to remodelling respiratory epithelium

Abstract

Pseudomonas aeruginosa is an opportunistic organism, which frequently colonizes the respiratory tract of patients with impaired host defence. In cystic fibrosis (CF) patients, this pathogen causes a progressive destructive bronchitis and bronchiolitis and is responsible for high mortality. Normal respiratory epithelium is protected against bacteria via mucus and mucociliary clearance. Alteration of mucociliary clearance and of glycosylation of mucins in CF facilitates the access of bacteria to the underlying airway epithelial cells. Intact respiratory epithelium does not bind P. aeruginosa, whereas injured respiratory epithelium is highly susceptible to P. aeruginosa adherence. We found that the high affinity of respiratory epithelium, from CF and non-CF sources, for P. aeruginosa, during the wound repair process is related to the apical expression of asialo ganglioside M1 (aGM1). The affinity of repairing respiratory epithelium for P. aeruginosa is time-dependent, and is related to transient apical expression of aGM1 at the surface of repairing respiratory epithelial cells. CF respiratory epithelial cells apically express more aGM1 residues with relation to an increased affinity for P. aeruginosa than non CF cells. High epithelial damage followed by repair represents a major cause of P. aeruginosa adherence to airway epithelium in cystic fibrosis. However, P. aerurignosa adherence and colonization are not restricted to cystic fibrosis disease and P. aeruginosa pneumonia may also occur in severely immunocompromised patients, suggesting that epithelial injury and decreased host-response favour the colonization of the airways by P. aeruginosa.