骨吸収からみた中耳疾患の病態について : OPGノックアウトマウスを用いた検討から The mechanism of bone resorption in middle ear diseases
Bone mineral density and morphology of the three auditory ossicles, malleus, incus, and stapes, are maintained by osteoclasts and osteoblasts. However, correlation between bone resorptive changes in the ossicles and hearing loss has not been established. In this review, we discuss osteoporotic changes of the auditory ossicles and pathology of middle ear diseases through the study of mice lacking osteoprotegerin (<I>Opg</I><SUP>-/-</SUP>mice), a soluble decoy receptor for the osteoclastogenic cytokine RANKL. All three ossicles in <I>Opg</I><SUP>-/-</SUP>mice showed thinning and shortening compared to wild-type controls. Most notably, the junction between the stapes and the otic capsule was fused in <I>Opg</I><SUP>-/-</SUP>mice unlike in wild-type mice. Furthermore, progressive hearing loss was detected in <I>Opg</I><SUP>-/-</SUP>mice starting at 6 to 15 weeks of age. These data suggest that OPG plays a crucial role as "audioprotegerin" in hearing by protecting the auditory ossicles and otic capsule from osteoclastic bone resorption. We also discuss clinical implications of resorption of the ossicles for middle ear diseases including otosclerosis and cholesteatoma.
- Otology Japan
Otology Japan 17(3), 168-172, 2007-07-25
THE JAPAN OTOLOGICAL SOCIETY