Pericellular glycoconjugates of cultured fibroblasts from control and cystic fibrosis patients

Terminal glycosylation in cystic fibrosis

Cystic fibrosis (CF) is a common genetic disease for which the gene was identified within the last decade. Pulmonary disease predominates in this ultimately fatal disease and current therapy only slows the progression. CF transmembrane regulator (CFTR), the gene product, is an integral membrane glycoprotein that normally functions as a chloride channel in epithelial cells. The most common mutation, deltaF508, results in mislocalization and altered glycosylation of CFTR. Altered fucosylation and sialylation are hallmarks of both membrane and secreted glycoproteins in CF and the focus here is on these investigations. Oligosaccharides from CF membrane glycoproteins have the Lewis x, selectin ligand in terminal positions. In addition, two major bacterial pathogens in CF, Pseudomonas aeruginosa and Haemophilus influenzae, have binding proteins, which recognize fucose in alpha1,3 linkage and asialoglycoconjugates. We speculate that the altered terminal glycosylation of airway epithelial glycoproteins in CF contributes to the chronic infection and robust inflammatory response in the CF lung. Understanding the effects of mutant CFTR on glycosylation may provide further insight into the regulation of glycoconjugate processing as well as therapy for CF.

Altered carbohydrate composition of salivary mucins from patients with cystic fibrosis and the adhesion of Pseudomonas aeruginosa

We compared the chemical composition of salivary mucin glycopeptides from cystic fibrosis (CF) and from non-CF subjects and the adhesion of Pseudomonas aeruginosa to these different salivary glycopeptides. Three pools of CF saliva, four pools of non-CF saliva, one individual CF saliva, and one individual non-CF saliva were studied. The soluble fraction of the saliva was treated with pronase, and gel filtration was performed to obtain high and low molecular mass salivary mucin glycopeptides. The yield of total glycopeptides was significantly higher from CF than from non-CF saliva. Furthermore, the chemical composition revealed a significantly higher sialic acid content in CF than in non-CF mucin glycopeptides, and higher sulfate and fucose content in CF than in non-CF high molecular mass glycopeptides. We studied the adhesion of a nonmucoid strain of P. aeruginosa (1244), its nonpiliated isogenic derivative, and a mucoid strain (M35) to salivary mucin glycopeptides from patients with CF and from non-CF subjects. The three strains bound significantly more to the CF salivary glycopeptides than to the corresponding non-CF salivary glycopeptides. The nonpiliated isogenic mutant of P. aeruginosa 1244 also bound to CF salivary glycopeptides, suggesting that the adhesion of P. aeruginosa could involve nonpilus adhesions. Furthermore, neuraminidase treatment of CF glycopeptides decreased the adhesion of P. aeruginosa 1244. Altogether these results suggested that differences in mucins may in part explain the specificity of P. aeruginosa for CF.