Stimulation by fibronectin of macrophage-mediated phagocytosis of Pseudomonas aeruginosa

Abstract

In a previous investigation it was determined that Pseudomonas aeruginosa cells taken directly from a mouse in vivo growth system were significantly more susceptible to nonopsonic phagocytosis by macrophages than were similar cells after being washed in buffer (N.

Cell adhesion protein fibulin‐7 and its C‐terminal fragment negatively regulate monocyte and macrophage migration and functionsin vitroandin vivo

“…Fibronectin is expressed by various cell types, including macrophages, endothelial cells, and smooth muscle cells (23,24), and it is implicated in the modulation of immune cell functions (23,25,26). The activation of immune cells, such as macrophages and T lymphocytes, increases their attachment to fibronectin, which suggests an important function of fibronectin in host defenses (24).…”

Mechanisms of nonopsonic phagocytosis of Pseudomonas aeruginosa

“…Bacterial strains and growth conditions. The P. aeruginosa strains used were the wild-type strain H103 (15) and its nonmotile, rough, piliated derivative H237, kindly provided by A. Kropinski (Department of Microbiology, Queen's University, Ontario, Canada) and the PAK parental wildtype strain and its rpoN mutant derivative NIG, which * Corresponding author. carries a gentamicin resistance cassette in the rpoN gene (4), kindly provided by S. Lory (Department of Microbiology, University of Washington, Seattle).…”

“…Pseudomonas aeruginosa is susceptible to phagocytic killing by macrophages in both the presence and absence of opsonins, such as specific antibody (7,15,26). It was previously demonstrated that exposure of macrophages to fibronectin resulted in subsequent enhancement of nonopsonic phagocytosis of P. aeruginosa (14,15,29). This occurred regardless of the fibronectin source and with the P388D1 macrophage cell line, with nonelicited mouse peritoneal macrophages, and with human monocyte-derived macrophages (15).…”

“…They are involved in phagocytosis but also have an important role in amplification of host immune responses, mediation of inflammatory responses, and processing and presentation of antigens. Pseudomonas aeruginosa is susceptible to phagocytic killing by macrophages in both the presence and absence of opsonins, such as specific antibody (7,15,26). It was previously demonstrated that exposure of macrophages to fibronectin resulted in subsequent enhancement of nonopsonic phagocytosis of P. aeruginosa (14,15,29).…”

“…The bacterial ligand involved in fibronectin-stimulated nonopsonic phagocytosis was the bacterial pilus, and it was proposed that fibronectin upregulated the exposure of pilus receptors in macrophages and macrophage cell lines (14). However, our previous studies suggested that there was a substantial background association of P. aeruginosa with macrophages that was not pilus mediated or stimulated by fibronectin (14,15). In this study, we have investigated the mechanisms of nonopsonic phagocytosis, with particular reference to fibronectin stimulation.…”