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

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Abstract
Pseudomonas aeruginosa plays an important role in the colonization of the airways of patients suffering from cystic fibrosis. It binds to the carbohydrate part of respiratory and salivary mucins and its binding to cystic fibrosis 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 flow cytometry technique using a panel of polyacrylamide based glycoconjugates labeled with fluorescein was developed. The neoglycoconjugates contained neutral, sialylated or sulfated chains analogous to carbohydrate determinants found at the periphery of respiratory mucins (Lea, Ley, Lex, sialyl- and 3′-sulfo-Lex, and blood group A determinants). We used also neoglycoconjugates containing Gal(α1–2)Galβ and sialyl-N-acetyllactosamine determinants. The interaction of these glycoconjugates with the nonpiliated strain of P.aeruginosa, 1244-NP, was saturable except for the glycoconjugates 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-Lex determinant than for all the other glycoconjugates studied. The role of sialic acid was confirmed by competition assay using mainly sialylated mucin glycopeptides. In order to find out if this behavior was the same for pathological strains as for the 1244-NP mutant, four mucoid strains of P.aeruginosa isolated from cystic fibrosis patients were analyzed with the Lex neoglycoconjugate, its sialylated and its sulfated derivatives. Individual variations in the binding of these strains to the three glycoconjugates were observed. However, three strains out of four had a higher affinity for the sialyl-Lex than for the 3′-sulfo-Lex derivative.