Role of Fibronectin in the Prevention of Adherence of Pseudomonas aeruginosa to Buccal Cells

Abstract

Recent evidence suggests that colonization of the upper respiratory tract by gram-negative bacilli is mediated by adherence to regional epithelial cells. Buccal epithelial cells were obtained for study from 12 seriously ill patients, all of whom were colonized with Pseudomonas aeruginosa. In comparison to cells from uncolonized controls, cells obtained from these patients attached significantly more P. aeruginosa organisms during incubation in vitro. Although the sialic acid content of colonized patients' cells was less than that of controls' cells, removal of sialic acid from normal cells with neuraminidase did not increase bacillary adherence. Trypsinization of normal cells increased bacillary adherence and significantly reduced the amount of fibronectin on the cell surface. Both trypsinized normal cells and cells recovered from seriously ill colonized patients attached large numbers of P. aeruginosa organisms in vitro and demonstrated decreased fibronectin on the cell surface by immunofluorescent staining. These findings suggest that the host alteration associated with increased susceptibility to adherence by P. aeruginosa is the loss of fibronectin from the cell surface.

Fibronectin-Cleaving Activity in Bronchial Secretions of Patients with Cystic Fibrosis

“…Although the correlation between colonization with gram-negative bacilli of the upper respiratory tract and the absence of fibronectin on buccal epithelial surfaces is well documented [7][8][9][10]35], the significance of the absence of surface fibronectin from the lower-respiratory-tract epithelium as a factor favoring colonization with gram-negative bacteria is unknown. Acid injury favors adherence of mucoid and nonmucoid P. aeruginosa to tracheal epithelium [36], but whether acid injury destroys fibronectin on cell surfaces is not known.…”

“…When the Figure 1. Top, proteolytic activity of I ul, of a pool of cystic fibrosis bronchial secretions against purified fibronectin after 0, 1,5, 10, IS, 30, and 60 min of incubation at 37 C, The proteolysis of fibronectin was examined by PAGE (running gel, 7,5l1Jo [wt/volJ) and subsequent immunoblotting. The molecular weights were monitored using standard proteins (Biorad).…”

“…Coloniza-tion of the upper respiratory tract with bacterial pathogens is achieved by binding of bacteria to epithelial cell surfaces. Severalexperimental studies have shown that the type of bacteria binding to epithelial surfaces is influenced by the presence of fibronectin, a glycoprotein on the cell surface [7][8][9][10][11]. The absence of fibronectin on epithelial cell surfaces from patients with cystic fibrosis [9] as well as from seriously ill patients with acute respiratory failure [10] correlated with increased adherence of P. aeruginosa to buccal epithelial cells.…”

Management of bacterial keratitis: beyond exorcism towards consideration of organism and host factors

“…Whereas Gram-positive bacteria, including S. aureus, adhere to host tissues via fibronectin and collagen, 15 P. aeruginosa attaches to cell surfaces that lack fibronectin. 16 Bacteria adhere to injured cornea, 17 to exposed corneal stroma, 18 or to immature nonwounded cornea. 19 The corneal epithelial receptors for Pseudomonas spp are glycoproteins.…”

Relationship between cytomegalovirus and colonization of the oropharynx by Gram-negative bacilli following renal transplantation

“…Previous investigations have shown that fibronectin, a high molecular weight glycoprotein, covers oral epithelial cell surface receptors for Gram-negative bacilli, thereby preventing adherence of these bacteria to such cells [22,23]. In severely ill patients, excess proteolytic enzyme activity in oral secretions cleaves fibronectin from cell surfaces [24], thus potentiating adherence of Gram-negative bacteria to buccal epithelial cells and in this way promoting colonization of the oropharynx [25].…”