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 journalArticle

56 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
Externally publishedYes

Keywords

  • Aggregation substance
  • Complement receptor
  • Enterococcus faecalis
  • Neutrophil

ASJC Scopus subject areas

  • Immunology
  • Microbiology
  • Infectious Diseases

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