Between Pseudomonas aeruginosa adhesins and human salivary, tracheobronchial and nasopharyngeal mucins

Endogenous aspiration of nasooropharyngeal secretions is a major source of Pseudomonas aeruginosa to lungs. To understand the mechanism of binding between P. aeruginosa and nasooropharyngeal secretions, we have utilized an overlay binding assay employing P. aeruginosa nonpilus protein adhesins (18 kDa and 15 kDa) and mucins from human saliva, tracheobronchial and nasopharyngeal secretions. Nasopharyngeal mucin bound to both the 18 kDa and 15 kDa adhesins. A high molecular weight salivary mucin and tracheobronchial mucin bound only to the 18 kDa adhesin. On the other hand, asialonasopharyngeal and asialotracheobronchial mucins did not bind to either of the adhesins. Binding of nasopharyngeal mucin to the 18 kDa and 15 kDa was not inhibitable by glycoproteins, bovine submaxillary mucins and sialic acid. Further, a low molecular weight salivary mucin which contains sialylated oligosaccharides also did not bind to either of the adhesins. Collectively, the results suggest that binding between P. aeruginosa and mucins may involve specific receptors and adhesins.