Mycoplasma-mediated bone resorption in bone organ cultures.

Mycoplasmas have been identified as one of many aetiological factors associated with experimental or human joint disease. Mycoplasma hyorhinis and M. arthritidis, but not M. pulmonis were found to cause significant release of calcium from murine long bone explants. The resorption process is inhibited by calcitonin, acetazolamide and by indomethacin. Mycoplasma-derived bone resorbing activity (M-BRA) is not an endotoxin as its effect is equally potent in cultures of bones obtained from endotoxin-responsive and -unresponsive mice. M-BRA is a high molecular weight compound resistant to proteases and heat but sensitive to hyaluronidase, lipase, detergents and in part to alkali and acid conditions. The active component is associated with the particulate fraction of the mycoplasma and its yield is enhanced by sonication. The damage to the subchondral bone in arthritis associated with a mycoplasma infection may be caused by a potent bone resorption inducing agent of mycoplasma origin.