Pseudomonas aeruginosa and Pseudomonas cepacia isolated from cystic fibrosis patients bind specifically to gangliotetraosylceramide (asialo GM1) and gangliotriaosylceramide (asialo GM2)

Abstract

Pseudomonas aeruginosa infection in the lungs is a leading cause of death of patients with cystic fibrosis, yet a specific receptor that mediates adhesion of the bacteria to host tissue has not been identified. To examine the possible role of carbohydrates for bacterial adhesion, two species of Pseudomonas isolated from patients with cystic fibrosis were studied for binding to glycolipids. P. aeruginosa and P. cepacia labeled with 125I were layered on thin-layer chromatograms of separated glycolipids and bound bacteria were detected by autoradiography. Both isolates bound specifically to asialo GM1 (Gal beta 1-3GalNAc beta 1-4Gal beta 1-4Glc beta 1-1Cer) and asialo GM2 (GalNAc beta 1-4Gal beta 1-4Glc beta 1-1Cer) but not to lactosylceramide (Gal beta 1-4Glc beta 1-1Cer), globoside (GalNAc beta 1-3Gal alpha 1-4Gal beta 1-4Glc beta 1-1Cer), paragloboside (Gal beta 1-4GlcNAc beta 1-3Gal beta 1-4Glc beta 1-1Cer), or several other glycolipids that were tested. Asialo GM1 and asialo GM2 bound the bacteria equally well, exhibiting similar binding curves in solid-phase binding assays with a detection limit of 200 ng of either glycolipid. Both isolates also did not bind to GM1, GM2, or GDla suggesting that substitution of the glycolipids with sialosyl residues prevents binding. As the Pseudomonas do not bind to lactosylceramide, the beta-N-acetylgalactosamine residue, positioned internally in asialo GM1 and terminally in asialo GM2, is probably required for binding. beta-N-Acetylgalactosamine itself, however, is not sufficient as the bacteria do not bind to globoside or to the Forssman glycolipid. These data suggest that P. aeruginosa and P. cepacia recognize at least terminal or internal GalNAc beta 1-4Gal sequences in glycolipids which may be receptors for these pathogenic bacteria.