| Background and AimsCholesteatoma is a common disease which seriously does harmful to patient's life in clinic. Its essential damages is the bony destruction of middle ear, causing hearing loss, intracranial or extracranial complication , resulting in death in the end .Although cholesteatoma may be present for many years, its mechanism of bone resorption has still not been well understood. Recent studies have proved that it is associated with factors following: The first is cytokine. Localized inflammatory reaction plays an important role in bone remodeling. Plenty of tests of molecular biology show that many cytokines (for example, Interleukin, tumor necrosis factor, et al.) are expressed significantly in cholesteatoma. The second is proteolytic enzymes that can be examined in cholesteatoma. One of them is matrix metalloproteinases which are focused on frequently recently. They can digest extracelluar matrix and bony matrix, inducing bone resorption , which shows they are partly responsible for bone destruction. The third is the change of extracellular matrix. It is suggesting that the change is an essential point in cholesteatoma. The aim of this study is to observe the expression of the three factors, clarify their relationship and then investigate the correlation between them and the extent of bone destruction .MethodsCholesteatoma specimens were collected at time of surgery, fixed immediately and made into paraffin section. At the same time the extent of bone destruction was noted. Immunohistochemical method and the computer image quantitative analysis were used to examine the expression of TNF-α MMP-9 and collagen type IV in 22 samples (4-5 m paraffin sections) from cholesteatoma and 20 normal cases. In addition, the correlation between the expressions of the three indexes and the erosion of ossicles were observed. The aim is to elucidate the mechanism of bone destruction.Results1 . The positive immunostaining of MMP-9 and TNF-α appeared brow granular distribution. MMP-9 protein was localized mostly in the cytoplasm, a small part of the nuclei was stained ;TNF- a protein was mainly expressed in cytoplasm , part of cell membranes were stained .2. In cholesteatoma and EACS, MMP-9 protein was only expressed in cholesteatoma stromal cells but not in epithlium. In EACS, it was only expressed in dermis and subcutaneous tissue. Its positive immunostaining rates were respectively 81.8%(18/22), 45.0%(9/20), there was statistical significance among the two groups(P=0.013); TNF-α was expressed in both epithlium and stromal cells, its positive rates was 72.2%( 16/20) , 35.0%(7/20), there also was statistical significance among the two groupsCP=0.014).3. The results of the computer image quantitative analysis showed that the mean optical density of MMP-9 was 0.2720 0.042 15 in cholesteatoma stroma and 0.2231 0.01949 in EACS, both of which had significantly differentiation(P=0.003); the mean optical density of TNF-α was 0.38 14±0.05783 in cholesteatoma (epithlium and stroma) and 0.2718 + 0.02102 in EACS, both of which had significantly differentiation(P=0.000); in addition, by relation analyse we found that over-expression of MMP-9 is significantly associated with the expression of TNF-α ( r-0.827 P=0.000).4. In 18 samples of cholesteatoma in which MMP-9 was expressed, 1 in OO, 2 in Ol,9 in 02 and 6 in O3. Statistical analysis showed that the positive immunostaining rates between the four grades had no significantly differentiation (P=0.363). But the mean optical density of MMP-9 between them had significant difference (P=0.001), suggesting that MMP-9 is relative to the extent of ossicle destruction.5. In 16 samples of cholesteatoma in which TNF-α was expressed , 1 in OO , 1 in O1 , 8 in O2 and 6 in O3. Statistical analysis showed that the positive immunostaining rates between the four grades had no significantly differentiation(P=0. 1 83), the mean o...
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