Enterococcus faecalis aggregation substance promotes opsonin-independent binding to human neutrophils via a complement receptor type 3-mediated mechanism

Natalie N. Vanek, Scott I. Simon, Karen Jacques-Palaz, M. Michele Mariscalco, Gary M. Dunny, Robert M. Rakita

Research output: Contribution to journalArticlepeer-review

57 Scopus citations

Abstract

Enterococcus faecalis aggregation substance (AS) mediates efficient adhesion between bacteria, thereby facilitating plasmid exchange as an integral part of a bacterial sex pheromone system. We examined the interaction of AS-bearing E. faecalis with human neutrophils (PMNs), an important component of the host defense system. AS promoted a markedly increased opsonin-independent bacterial binding to PMNs. Adhesion was dependent on the expression of the enterococcal Asc10 protein, which contains two Arg-Gly-Asp (RGD) sequences, and addition of exogenous RGD-containing peptides inhibited AS-mediated binding by 66%. AS-mediated adhesion was inhibited by 85% by anti-human complement receptor type 3 (CR3) monoclonal antibodies or by use of PMNs from a patient with leukocyte adhesion deficiency. However, AS-bearing E. faecalis cells were unable to bind to CHO- Mac-1 cells, expressing functionally active CR3, suggesting the potential need for additional PMN surface receptors for bacterial adhesion. Monoclonal antibodies against integrin-associated protein (CD47) and L-selectin, both of which may interact with CR3 and bind to ligands on E. faecalis, also inhibited AS-dependent binding. The non-opsonic binding of E. faecalis to PMNs may play an important role in this organism's pathogenesis.

Original languageEnglish (US)
Pages (from-to)49-60
Number of pages12
JournalFEMS Immunology and Medical Microbiology
Volume26
Issue number1
DOIs
StatePublished - Oct 1999

Bibliographical note

Funding Information:
We thank Robert Jordon for use of the fluorescence microscope, Dawn Manias and Mee Mee for technical assistance, Patti Navarro for assistance with electron microscopy, Eric Brown, Nancy Hogg, R. Rothlein, J. Rusche, David Chambers, Karl Arfors and Cell Genesys for providing monoclonal antibodies, Timothy Springer and Mario R.W. Ehlers for providing CHO-Mac-1 cells and Barbara Murray and George Weinstock for advice and support. This work was supported by Grants-in-Aid from The American Heart Association, Texas Affiliate and National (to RMR) and grants from the NIH (AI31652 to SIS, AI19031 to MMM, HL51987 to GMD). SIS is an Established Investigator of the American Heart Association.

Keywords

  • Aggregation substance
  • Complement receptor
  • Enterococcus faecalis
  • Neutrophil

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