Human Monocyte-Derived Osteoclasts Are Targeted by Staphylococcal Pore-Forming Toxins and Superantigens

PLoS One. 2016 Mar 2;11(3):e0150693. doi: 10.1371/journal.pone.0150693. eCollection 2016.

Abstract

Staphylococcus aureus is the leading cause of bone and joint infections (BJIs). Staphylococcal pathogenesis involves numerous virulence factors including secreted toxins such as pore-forming toxins (PFTs) and superantigens. The role of these toxins on BJI outcome is largely unknown. In particular, few studies have examined how osteoclasts, the bone-resorbing cells, respond to exposure to staphylococcal PFTs and superantigens. We investigated the direct impact of recombinant staphylococcal toxins on human primary mature monocyte-derived osteoclasts, in terms of cytotoxicity and cell activation with cell death and bone resorption assays, using macrophages of the corresponding donors as a reference. Monocyte-derived osteoclasts displayed similar toxin susceptibility profiles compared to macrophages. Specifically, we demonstrated that the Panton-Valentine leukocidin, known as one of the most powerful PFT which lyses myeloid cells after binding to the C5a receptor, was able to induce the death of osteoclasts. The archetypal superantigen TSST-1 was not cytotoxic but enhanced the bone resorption activity of osteoclasts, suggesting a novel mechanism by which superantigen-producing S. aureus can accelerate the destruction of bone tissue during BJI. Altogether, our data indicate that the diverse clinical presentations of BJIs could be related, at least partly, to the toxin profiles of S. aureus isolates involved in these severe infections.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Toxins / metabolism*
  • Bone Resorption / complications
  • Bone Resorption / metabolism
  • Bone Resorption / microbiology
  • Bone Resorption / pathology
  • Cells, Cultured
  • Enterotoxins / metabolism*
  • Exotoxins / metabolism*
  • Host-Pathogen Interactions*
  • Humans
  • Leukocidins / metabolism*
  • Monocytes / metabolism
  • Monocytes / microbiology*
  • Monocytes / pathology
  • Osteoclasts / metabolism
  • Osteoclasts / microbiology*
  • Osteoclasts / pathology
  • Staphylococcal Infections / complications
  • Staphylococcal Infections / metabolism
  • Staphylococcal Infections / microbiology
  • Staphylococcal Infections / pathology*
  • Staphylococcus aureus / physiology*
  • Superantigens / metabolism*

Substances

  • Bacterial Toxins
  • Enterotoxins
  • Exotoxins
  • Leukocidins
  • Panton-Valentine leukocidin
  • Superantigens
  • enterotoxin F, Staphylococcal

Grants and funding

This work was supported by a grant from Fondation Innovation en Infectiologie, Lyon, France (grant AO6) http://www.finovi.org. The funder had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.