Degradation of the type Ⅱ collagen network early in the degeneration of cartilage

第二類膠原蛋白纖維結構在初期退化性關節軟骨中的降解變化

陳敏慧(Min-Huey Chen) ； 陳羿貞(Yi-Jane Chen) ； 姚宗珍(Chung-Chen Jane Yao)

《中華牙醫學雜誌》 23卷4期 (2004/08) Pp. 255-265

https://doi.org/10.7105/CDJ.200408.0255

摘要

關節軟骨主要的作用在於承受並分擔關節骨部位的力量，減少對於骨骼直接的碰撞力，軟骨在初期的退化性變化中會有軟化的現象，正常軟骨則呈現較好的彈性；推測造成“軟化”軟骨的現象是由於軟骨中的第二類型膠原蛋白纖維之間的鍵結結構破壞所造成。本實驗之目的即是在探討第二類型膠原蛋白纖維在軟化軟骨中的超顯微結構變化，正常軟骨取自牛關節的股骨關節而軟化軟骨則取自受力較多的脛骨關節面，以諾曼斯汀光學顯微鏡及穿透性電子顯微鏡分別觀察顯微及超顯微結構，並以免疫組織化學染色法染出第Ⅱ類型膠原蛋白纖維在正常軟骨與軟化軟骨的分佈，再以共軛焦顯微鏡觀察，足以顯示在關節軟骨初期退化的變化中主要是第Ⅱ類膠原蛋白纖維的鍵結破壞所致。本實驗是首度以超顯微結構加上應用共軛焦顯微鏡顯示關節軟骨在退化性變化中第二類膠原蛋白纖維結構的變化。

關鍵字

關節軟骨 ； 第二類膠原蛋白纖維降解 ； 共軛焦頭顯微鏡

並列摘要

Type II collagen has been characterized as being present in joint tissues subjected to compression rather than tension. The purposes of this study were to investigate the distribution and ultrastructural changes in the type II collagen fibrillar network in the early stage of degeneration of cartilages. Softened cartilage which represents the early stage of degeneration was obtained from the tibial surfaces of a cow. Normal control cartilage was obtained from the femoral condyles in the same joint. Nomarski light microscopy and transmission electron microscopy (TEM) were performed respectively for structural and ultrastructural studies. Confocal light micrscopy was applied for imaging the staining of collagen type II in normal and softened matrices by immunohistochemical studies. The results demonstrated that in normal cartilage the extracellular matrix was characterized by a fine ”ground-glass-like” amorphous texture. This reflects the fact that individual fibril elements in their repeatedly interconnecting configuration present a fineness of structure that is beyond the limits of optical resolution. The normal matrix observed by TEM was shown to have a pseudo-randam fibrillar architecture. The extracellular matrix in the softened cartilage was characterized by a distinct fibrous texture strongly aligned in the radial direction. This optically resolved structural feature of the softened matrix reflects a tendency for individual collagen flbrils to aggregate into relatively large fibrillar bundles strongly aligned in the radial direction as observed under TEM. The type II collagen-labeled images obtained from the normal matrix exhibited a fine texture. By contrast, staining of the softened matrix exhibited a relatively coarse granularity with a distinctly radial texture in the deeper zones. It was concluded that the degeneration of cartilage begins with degeneration of the extracellular matrix, and the decrease in collagen fibrillar interactions is mainly caused by the loss of cross-linking in type II collagen. This is the first report to correlate ultrastructural changes of the fibrillar network with confocal imaging of the type II collagen distribution in the process of cartilage degeneration.

並列關鍵字

articular cartilage ； typeⅡcallagen degradation ； confocal microscopy