Estradiol ameliorates arthritis and protects against systemic bone loss in Staphylococcus aureus infection in mice

INTRODUCTION: Staphylococcus aureus is a common cause of bacterial arthritis, which is associated with progressive bone loss in affected joints. We recently showed that S. aureus infection also induces a significant systemic bone loss in mice. This study was performed to assess the effect of estradiol treatment on the clinical course and outcome of S. aureus arthritis and on infection-induced bone loss in experimental S. aureus infection. METHODS: Mice were ovariectomized, treated with estradiol or placebo, and S. aureus infection was established by intravenous inoculation of bacteria. RESULTS: Estradiol treatment was found to decrease significantly the frequency and clinical severity of S. aureus arthritis, a finding that was accompanied with significantly higher serum levels of interleukin-10 in estradiol-treated mice. Estradiol was also highly protective against S. aureus-induced systemic trabecular, and cortical bone loss. Lack of endogenous estrogens and S. aureus infection had additive effects on trabecular bone loss. The S. aureus-infected, ovariectomized mice lost as much as 76% of their trabecular bone mass. CONCLUSIONS: Treatment with estradiol ameliorates S. aureus arthritis and is protective against infection-induced systemic bone loss in experimental S. aureus infection.