BACTERIA INHIBIT BIOSYNTHESIS OF BONE-MATRIX PROTEINS IN HUMAN OSTEOBLASTS

The effect of extracts from Staphylococcus aureus and Staphylococcus e pidermidis on bone matrix production were assessed by analyzing the bi osynthesis of osteocalcin and Type I collagen in a human osteoblastic osteosarcoma cell line (MG-63). In MG-63 cells, extracts from Staphylo coccus aureus and Staphylococcus epidermidis decreased 1,25(OH)(2)-vit amin D-3 stimulated osteocalcin biosynthesis, and insulinlike growth f actor I induced production of Type I collagen in a concentration depen dent manner, The basal rate of osteocalcin and Type I collagen formati on was unaffected by the bacterial extracts, The inhibitory effect of the bacteria on osteocalcin biosynthesis was seen after 24 hours of tr eatment and was maintained for at least 96 hours, The extracts of Stap hylococcus aureus and Staphylococcus epidermidis enhanced prostaglandi n E-2 formation in the MG-63 cells, Abolition of the prostaglandin E-2 response by treatment with indomethacin and flurbiprofen did not affe ct bacteria induced inhibition of osteocalcin production, Stimulation of osteocalcin biosynthesis by 1,25(OH)(2)-vitamin D-3 was associated with a decreased rate of cell proliferation, The inhibitory action of the bacterial extracts was not linked to any inhibition of [H-3]-thymi dine incorporation into deoxyribonucleic acid, These data show that ex tracts of Staphylococcus aureus and Staphylococcus epidermidis have th e ability to inhibit the biosynthesis of bone matrix proteins by a non prostaglandin and noncytotoxic dependent mechanism and suggest that bo ne loss in inflammatory processes containing Staphylococcus aureus or Staphylococcus epidermidis may not be caused only by enhanced bone res orption but also by decreased bone formation.