The effect of Staphylococcus aureus on apoptosis of cultured human osteoblasts.

Abstract

To investigate the effect of Staphylococcus aureus (S. aureus) on cultured human osteoblast apoptosis and the corresponding mode of action. Transmission electron microscopy (TEM), assessment of DNA laddering, and flow cytometry assays were used to investigate human osteoblast apoptosis following infection with S. aureus. TEM examination and DNA laddering assessment indicated that S. aureus can induce cultured human osteoblast apoptosis. Flow cytometry assays showed that human osteoblast apoptosis occurs in a dose-dependent manner following infection with S. aureus. In addition, compared with under co-culture conditions, inhibition of invasion by S. aureus resulted in a 64.62% reduction in the percentage of early apoptotic cells (P < 0.01); 7.09% ± 1.21% of human osteoblasts under indirect co-culture with S. aureus at a multiplicity of infection of 250 showed an early apoptotic profile compared with uninfected controls(P < 0.01). S. aureus induces cultured human osteoblast apoptosis in a dose-dependent manner. Intracellular S. aureus is mainly responsible for cultured human osteoblast apoptosis following infection; secreted soluble factor(s) of S. aureus playing a minor role in this process. © 2011 Tianjin Hospital and Blackwell Publishing Asia Pty Ltd.