Cystic fibrosis epithelial cells have a receptor for pathogenic bacteria on their apical surface.

Abstract

Chronic colonization and infection of the lung with Pseudomonas aeruginosa is the major cause of morbidity and mortality in cystic fibrosis (CF) patients. We found that polarized CF bronchial and pancreatic epithelia bound P. aeruginosa in a reversible and dose-dependent manner. There was significantly greater binding to CF bronchial and pancreatic cells than to their matched pairs rescued with the wild-type CF transmembrane conductance regulator. Bound P. aeruginosa were easily displaced by unlabeled P. aeruginosa but not by Escherichia coli, an organism that does not cause significant pulmonary disease in CF. In contrast, Staphylococcus aureus, a frequent pathogen in CF, could effectively displace bound P. aeruginosa from its receptor. We found undersialylation of apical proteins and a higher concentration of asialoganglioside 1 (aGM1) in apical membranes of CF compared with rescued epithelia. Colonization of the respiratory tract by Pseudomonas is present in most patients with cystic fibrosis (CF) (1). This infection occurs in infancy before significant inflammatory damage to the lung generates bronchiectasis (2). Younger patients often have antecedent pulmonary infections with Staphylococcus aureus, and they are frequently colonized by both S. aureus and Pseudomonas aeruginosa. Loss of function of the CF gene product [CF transmembrane conductance regulator (CFTR)] is responsible for chronic infection with Pseudomonas (3, 4) because the severity of the defect in CFTR function correlates both with the age at colonization (5) and with the extent of binding of Pseudomonas to respiratory cells taken from CF patients (6). However, the identification of CFTR as an apical membrane Cl-channel has not suggested why CF children are so readily infected with Pseudomonas.Adherence of bacteria to specific cellular receptors is the initial event in many infectious diseases (7-9). In an in vitro assay, P. aeruginosa bound to asialoganglioside 1 (aGMi) and aGM2 but not to the sialylated homologues GM1 and GM2 (10). Respiratory cells from CF patients had more aGM1 than normal cells (11). In fact, undersialylation is also found in mucus glycoproteins of clinical specimens and in secretions from immortalized CF cell lines (12). We recently proposed that loss of the CFTR Cl-channel from intracellular glycosylation compartments impairs sialyltransferase activity (13,14). Thus, we hypothesized that defective sialylation of gangliosides generates Pseudomonas receptors (13, 14), and we show here that there are a larger number of these receptors on the apical surfaces of CF epithelia.MATERIALS AND METHODS Cells and Bacteria. CF bronchial epithelial cells, IB3 (genotype AF508/W1282X), and a matched rescued control cell line, C38, were from P. Zeitlin, Johns Hopkins University (15). These cells were maintained in LCH-8 medium (Biofluids, Rockville, MD) at 37°C in 5% C02/95% air. The second CF epithelial cell line, CFPAC (genotype AF508/AF508), and its matched rescued control cell line, CFPAC/CFTR, were from M. Drumm, University ...

Genetic features of Pseudomonas aeruginosa isolates from cystic fibrosis patients compared with those of isolates from other origins

“…The nature of the protein encoded by this gene in P. aeruginosa PAO1 is unknown (Stover et al, 2000). Several arguments suggest that nan1 encodes a sialidase, an enzyme theoretically able to release sialic acid from sialylated gangliosides, thus increasing the amount of asialoGM1, a major receptor for adherence to the respiratory tract (Bryan et al, 1998;de Bentzmann et al, 1996;Imundo et al, 1995;Saiman et al, 1992;Saiman & Prince, 1993). The first argument is that the deduced bacterial protein encoded by nan1 possesses four Asp-boxes, a characteristic of bacterial sialidases (Taylor, 1996;Vimr, 1994).…”

Transgenic Cystic Fibrosis Mice Exhibit Reduced Early Clearance of Pseudomonas aeruginosa from the Respiratory Tract

“…These include decreased bacterial killing due to ineffective antimicrobial peptides (21,23,24), increased adherence of P. aeruginosa to respiratory epithelial cells of CF patients (25,26), and decreased bacterial clearance from the periciliary layer above the epithelial cells due to dehydration (27,28). Although all of these hypotheses include factors that could contribute to decreased removal of P. aeruginosa from the lungs of CF patients, none adequately explain the high-level association of P. aeruginosa infection with CF.…”

Cellular heterogeneity of CFTR expression and function in the lung: implications for gene therapy of cystic fibrosis

“…Direct interaction with epithelial cells: Two additional mechanisms of bacterial colonization in the airway propose the direct interaction of bacteria with surface epithelial cells. One such mechanism includes enhanced binding of bacteria to biochemically altered surface glycoproteins 78,79,[81][82][83] as a result of intracellular defects in glycoprotein processing compartmentes of CF cells. [58][59][60] A second mechanism proposes that CFTR itself may serve as a receptor for P. aeruginosa and play a role in bacterial clearance from the airway.…”