Vaughan-Thomas Anne, Dudhia Jayesh, Bayliss Michael T, Kadler Karl E, Duance Victor C
Faculty of Veterinary Science, University of Liverpool, Liverpool, UK.
Connect Tissue Res. 2008;49(5):374-82. doi: 10.1080/03008200802325417.
Recent studies have identified a range of interactions between type IX collagen and other cartilage matrix components. To determine the extent to which these interactions are important in maintaining the integrity of ageing articular cartilage, we analyzed an age range of normal healthy articular cartilage samples by Western blotting, immunohistochemical, and PCR analyses. Reduced levels of type IX collagen were detected in post adolescence cartilage. Type IX collagen epitopes were evident throughout the matrix in all cartilage samples up to 19 years of age. Post adolescence, however, the pattern of immunoreactivity revealed territorial staining only. Type IX collagen expression at the transcriptional level is maintained at all ages. Type IX collagen fragments were extracted from young tissue, supporting the hypothesis that young cartilage is continually remodelled, while mature cartilage maintains relatively low levels of collagen turnover. Clearly the age changes we observed may have significant effects on the integrity of the tissue as the chondrocytes in ageing articular cartilage have limited capacity to turnover the interterritorial matrix. However, this study provides evidence that even in old age, the chondrocyte attempts to maintain its pericellular environment and hence its mechanical role. Therefore, the potential of type IX collagen to interact with other matrix components continues to be of importance in the territorial environment, and these interactions may have significant roles in mechanotransduction.
最近的研究已经确定了IX型胶原蛋白与其他软骨基质成分之间的一系列相互作用。为了确定这些相互作用在维持衰老关节软骨完整性方面的重要程度，我们通过蛋白质免疫印迹、免疫组织化学和聚合酶链反应分析，对不同年龄段的正常健康关节软骨样本进行了分析。在青春期后的软骨中检测到IX型胶原蛋白水平降低。在19岁之前的所有软骨样本中，IX型胶原蛋白表位在整个基质中都很明显。然而，青春期后，免疫反应模式仅显示出区域染色。IX型胶原蛋白在转录水平的表达在所有年龄段都得以维持。从年轻组织中提取出了IX型胶原蛋白片段，这支持了以下假设：年轻软骨在持续重塑，而成熟软骨的胶原蛋白更新水平相对较低。显然，我们观察到的年龄变化可能会对组织的完整性产生重大影响，因为衰老关节软骨中的软骨细胞更新细胞间基质的能力有限。然而，这项研究提供了证据，表明即使在老年，软骨细胞仍试图维持其细胞周围环境，从而维持其机械功能。因此，IX型胶原蛋白与其他基质成分相互作用的潜力在区域环境中仍然很重要，并且这些相互作用可能在机械转导中发挥重要作用。
