LOX-1 Supports Adhesion of Gram-Positive and Gram-Negative Bacteria

Abstract

Adhesion of bacteria to vascular endothelial cells as well as mucosal cells and epithelial cells appears to be one of the initial steps in the process of bacterial infection, including infective endocarditis. We examined whether lectin-like oxidized low-density lipoprotein receptor 1 (LOX-1), a member of scavenger receptor family molecules with C-type lectin-like structure, can support adhesion of Gram-positive and Gram-negative bacteria. Chinese hamster ovary-K1 (CHO-K1) cells stably expressing LOX-1 can support binding of FITC-labeled Staphylococcus aureus and Escherichia coli, which was suppressed by poly(I) and an anti-LOX-1 mAb. Adhesion of these bacteria to LOX-1 does not require divalent cations or serum factors and can be supported under both static and nonstatic conditions. Cultured bovine aortic endothelial cells (BAEC) can also support adhesion of FITC-labeled S. aureus, which was similarly suppressed by poly(I) and an anti-LOX-1 mAb. In contrast, binding of FITC-labeled E. coli to BAEC was partially inhibited by the anti-LOX-1 mAb, and poly(I) did not block FITC-labeled E. coli adhesion to BAEC, but, rather, enhanced it under a static condition. TNF-α increased LOX-1-dependent adhesion of E. coli, but not that of S. aureus, suggesting that S. aureus adhesion to BAEC may require additional molecules, which cooperate with LOX-1 and suppressed by TNF-α. Taken together, LOX-1 can work as a cell surface receptor for Gram-positive and Gram-negative bacteria, such as S. aureus and E. coli, in a mechanism similar to that of class A scavenger receptors; however, other unknown molecules may also be involved in the adhesion of E. coli to BAEC, which is enhanced by poly(I).

Lectin-like oxidized LDL receptor-1 is a cell-adhesion molecule involved in endotoxin-induced inflammation

“…The multiple functions of LOX-1, such as the binding of bacteria, leukocyte adhesion, and superoxide generation, support the idea that LOX-1 might be working as a member of innate immunity (15,32), though excess activity of LOX-1 might result in the damage of organs. We conclude that manipulation of the activity of LOX-1 at appropriate levels would be beneficial for the control of inf lammation-related diseases.…”

Recognition of Staphylococcus aureus-derived peptidoglycan (PGN) but not intact bacteria is mediated by CD14 in microglia

“…Within this family we chose to investigate LOX-1 since this receptor has been reported to bind S. aureus directly (Shimaoka et al, 2001). LOX-1 mRNA expression was significantly elevated in response to both S. aureus and PGN (Fig.…”

The Pattern Recognition Receptor Dectin-1: From Fungi to Mycobacteria

“…LOX-1 which is an abbreviation for lectin-like oxidized low density lipoprotein receptor-1 is best known as a receptor for oxidized LDL and other host molecules such as fibronectin [9]. However, it has also been implicated in binding both gram-negative and gram-positive bacteria by endothelial cells and this binding appears to be mechanistically similar to binding by class A scavenger receptors [10]. Despite the limited ligand and functional information on the other members, sequence data suggests potential signaling motifs within their cytoplasmic tails.…”