Expression of Receptor Activator of NF-kappaB Ligand and Osteoprotegerin in Cholesteatoma

Byun, Jae Yong; Cha, Chang Il; Yeo, Seung Geun; Kim, Sung Wan; Cho, Joong Saeng

Abstract

BACKGROUND AND OBJECTIVES
Bone resorption in middle ear cholesteatoma is mostly responsible for serious complications of the disease, but the pathogenesis of destruction due to bone resorption has not been fully elucidated, although osteoclast activation have been indicated in reports to have a major effect. We have investigated if the receptor activator of NF-kappaB ligand (RANKL), a cytokine that is arguably the most critical regulator of osteoclast differentiation and activation and its natural inhibitor, osteoprotegerin (OPG), may be important in the bone loss of cholesteatoma. Also, we evaluated the correlation of RANKL and OPG level with the extent of bone destruction. SUBJECTS AND METHOD: A real time RT-PCR was performed to determine and quantify the expression of RANKL and OPG mRNA in 13 cases of cholesteatoma and 8 cases of normal auditory canal skin. RESULT: 1) All cholestatoma and normal external auditory canal skin expressed both mRNA of RANKL and OPG 2) mRNA of RANKL in cholesteatoma were expressed significantly higher than normal external auditory canal skin (p<0.05). 3). The ratio of RANKL to OPG concentration was significantly higher in cholesteatoma than in the normal external auditory canal skin (p<0.05). 4) The ratio of RANKL to OPG was significantly correlated to the extent of bone destruction (p<0.05). CONCLUSION: These findings suggest the RANKL-OPG loop feedback system is defined in cholesteatoma. RANKL may play a role in the bone destruction of cholesteatoma. In particular, the balance in the ratio of RANKL to OPG is more important than RANKL.