Pseudomonas aeruginosa binds to neoglycoconjugates bearing mucin carbohydrate determinants and predominantly to sialyl-Lewis x conjugates

Pseudomonas aeruginosa plays an important role in the colonization of the a irways of patients suffering from cystic fibrosis, It binds to the carbohyd rate part of respiratory and salivary mucins and its binding to cystic fibr osis mucins is even higher, suggesting that qualitative or/and quantitative modifications of the carbohydrate chains may be involved in this process. In order to find out the best carbohydrate receptors for P.aeruginosa, a fl ow cytometry technique using a panel of polyacrylamide based glycoconjugate s labeled with fluorescein was developed. The neoglycoconjugates contained neutral, sialylated or sulfated chains analogous to carbohydrate determinan ts found at the periphery of respiratory mucins (Le(a), Le(y), Le(x), sialy l- and 3'-sulfo-Le(x), and blood group A determinants). We used also neogly coconjugates containing Gal(alpha 1-2)Gal beta and sialyl-N-acetyllactosami ne determinants. The interaction of these glycoconjugates with the nonpilia ted strain of P.aeruginosa, 1244-NP, was saturable except for the glycoconj ugates containing blood group A or sialyl-N-acetyllactosamine epitopes, The measure of Kd indicated that strain 1244-NP had a higher affinity for the glycoconjugate bearing the sialyl-Le(x) determinant than for all the other glycoconjugates studied. The role of sialic acid was confirmed by competiti on assay using mainly sialylated mucin glycopeptides, In order to find out if this behavior was the same for pathological strains as for the I244-NP m utant, four mucoid strains of P.aeruginosa isolated from cystic fibrosis pa tients were analyzed with the Le(x) neoglycoconjugate, its sialylated and i ts sulfated derivatives. Individual variations in the binding of these stra ins to the three glycoconjugates were observed, However, three strains out of four had a higher affinity for the sialyl-Le(x) than for the 3'-sulfo-Le (x) derivative.