Expression of RANKL(Receptor Activator of Nuclear Factor κB Ligand) and OPG(Osteoprotegerin) in middle ear cholesteatoma tissue.

Abstract

IDEA : Bone destruction at the middle due to cholesteatoma is known to be caused by various enzymes and cytokines. Especially, many studies that authenticate the role of osteoclast and related cytokines have been introduced . Recently, it has been clarified that formation and differentiation of osteoclast is activated by the binding of RANK and RANKL, and inhibited by the binding of RANKL and OPG. The objectives of this study is to examine the role of RANK-RANKL-OPG in cholesteatoma tissue. METHOD : An immunohistochemistry was carried out in 22 cholesteatoma tissues obtained during middle ear surgery and 5 normal postauricular skin tissues in order to examine the expression of RANKL and OPG. RESULTS : 1. All cases of 22 cholesteatoma and 5 normal postauricular skin expressed RANKL and OPG. 2. The count of positive expression cells of RANKL was 87.41± 19.31 in cholesteatoma, and 41.60± 11.10 in normal postauricular skin, which showed a higher count in cholesteatoma with statistical significance (p=0.001). The rate of positive expression cells of RANKL was 87.86± 5.96% in cholesteatoma, and 60.22± 4.01% in normal postauricular skin, which showed a higher rate in cholesteatoma with statistical significance (p=0.001). 3. The count of positive expression cells of OPG was 6.95± 2.92 in cholesteatoma, and 10.00± 1.23 in normal postauricular skin, which showed a higher count in normal postauricular skin (p=0.039). The rate of positive expression cells of OPG was 7.14± 2.75% in cholesteatoma, and 15.24± 0.63% in normal postauricular skin, which showed a higher rate in normal postauricular skin with statistical significance (p=0.001). 4. The ratio of positive expression rate of RANKL and OPG(positive expression cell rate of RANKL / positive expression cell rate of OPG) was 14.54± 6.67 in cholesteatoma, and 3.96± 0.23 in normal postauricular skin, which showed a higher ratio in cholesteatoma with statistical significance (p=0.001). 5. In a comparative study of clinical data, the duration of disease, degree of hearing loss, extent of invasion, degree of bone destruction showed no statistically significant interrelationship with the positive expression of RANKL and OPG. CONCLUSIONS : It might be suggested that RANKL, which activates osteoclast, plays a significant role in the mechanism of bone destruction in cholesteatoma, and the ratio of RANKL and OPG can be a more reliable parameter for bone destruction in cholesteatoma.