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.