Schuppan D, Rühlmann T, Hahn E G
Anal Biochem. 1985 Aug 15;149(1):238-47. doi: 10.1016/0003-2697(85)90501-9.
A liquid phase radioimmunoassay (RIA) was developed for pepsin-solubilized human type VI collagen, allowing quantitative analysis of this protein down to a concentration of 3 ng/ml. No cross-reactivity was observed with human collagens type I, III, IV (triple helical portion and 7-S domain), and V, nor with laminin fragment Pl and plasma fibronectin. Significant amounts of closely related antigenic material were detected in serum, bile, ascites, and mesenchymal cell culture media. Type VI collagen could be completely solubilized from several tissues by a repeated pepsin digest, and its content as determined by RIA was found to be less than 0.1% of total collagen (55-70 micrograms/g protein). In fibrotic liver tissue type VI collagen was elevated up to 10-fold (620 micrograms/g protein) when compared to normal liver. Sera of patients with fibrotic liver disease, however, revealed antigen levels usually below the narrow normal range of 22 +/- 7.8 ng/ml (mean +/- 2.5 SD). We conclude that, although type VI collagen represents a minor fraction of the interstitial collagens, its comparatively high serum levels point to a considerable turnover in the normal individual. Our data suggest that in fibrosis as exemplified in fibrotic liver disease, the metabolism of this collagen is down-regulated, while at the same time, it accumulates in the interstitial matrix.
已开发出一种针对胃蛋白酶溶解的人VI型胶原蛋白的液相放射免疫分析方法（RIA），可对低至3 ng/ml浓度的该蛋白进行定量分析。未观察到与I型、III型、IV型（三螺旋部分和7-S结构域）和V型人胶原蛋白以及层粘连蛋白片段P1和血浆纤连蛋白有交叉反应。在血清、胆汁、腹水和间充质细胞培养基中检测到大量密切相关的抗原物质。通过反复胃蛋白酶消化可从多种组织中完全溶解VI型胶原蛋白，通过RIA测定其含量发现其占总胶原蛋白（55-70微克/克蛋白质）的比例不到0.1%。与正常肝脏相比，纤维化肝组织中VI型胶原蛋白升高了10倍（620微克/克蛋白质）。然而，纤维化肝病患者的血清显示抗原水平通常低于22±7.8 ng/ml（平均值±2.5标准差）这一狭窄的正常范围。我们得出结论，尽管VI型胶原蛋白占间质胶原蛋白的比例较小，但其相对较高的血清水平表明在正常个体中其周转量相当可观。我们的数据表明，在如纤维化肝病所示的纤维化过程中，这种胶原蛋白的代谢受到下调，同时它在间质基质中积累。
