胰岛素样生长因子Ⅰ在骨赘发生过程中的基因表达

Gene expression of insulinlike growth factor-Ⅰ in the osteophyte development

目的研究胰岛素样生长因子Ⅰ在骨关节炎骨赘软骨发生过程中的基因表达特点。方法 25例接受全膝关节置换术的原发性骨关节炎骨赘标本为研究对象,3例正常成人股骨髁软骨标本作对照。制备石蜡切片,行 HE 和甲苯胺蓝染色及Ⅰ型胶原、Ⅱ型胶原(Ⅱa和Ⅱb)、X 型胶原分子的免疫组化染色。根据骨赘中主要组织的细胞形态学和各种胶原分子等的表达特点,共获得5种主要不同类型(Ⅰ～Ⅴ)的骨赘组织,然后分别进行胰岛素样生长因子Ⅰ的免疫组化和原位杂交染色。结果定量分析后进行单因素方差分析。结果免疫组化和原位杂交方法均显示胰岛素样生长因子Ⅰ主要在Ⅰ和Ⅱ类骨赘表达明显高于Ⅳ和Ⅴ类骨赘(14.6±3.8 vs 7.7±3.5;14.6±3.8 vs 6.0±1.9;14.2±4.6 vs 5.4±2.1;14.2±4.6 vs 2.2±1.5;P<0.05)。Ⅰ和Ⅱ类骨赘以及Ⅳ和Ⅴ类骨赘之间差异无统计学意义。结论胰岛素样生长因子Ⅰ-mRNA 主要在骨赘形成的早期明显表达;其对骨关节炎骨赘的发生可能起着始动作用。

Objective To investigate the gene expression and potential function of insulinlike- I in osteophyte development. Methods Specimens were obtained from 25 individuals undergoing total knee arthroplasty due to severe primary osteoarthritis and from 3 healthy adults. The tissue samples were embedded in paraffin wax and made into sections to undergo HE and toluidine blue staining. Immunohistochemistry was used to detect the expression of collagen I, Ⅱ a, Ⅱ b, and X. The osteophytic tissues were grouped into different types based on the results by histomorphology and expression of different collagens and glycosaminoglycans. Immunohistochemistry and in situ hybridization were used to detect the expression of insulinlike growth factor- I in the osteophyte. The images obtained by imunohistochemistry and in situ hybridization were put into the image analysis system to be analyzed semi-quantitatively. Results Based on the characteristics of histomorphology and expression of different collagens and glycosaminoglycans, the osteophytic tissues were grouped into five different types. The type I tissue mainly consists of mesenchymal fibroblast-like cells producing collagen I. The type Ⅱ tissue was characterized by the existence of collagen Ⅱ A expressed in prechondrocyte and glycosaminoglycans in the extracellular mesenchyma, he type III tissue was marked by the co-expression of collagen Ⅱ B, glycosaminoglycans, collagen Ⅱ A, and collagen I. The type IV tissue showed a clear zonal organization of chondrocytes, abundant expression of collagen Ⅱ B and glycosaminoglycans , and hypertrophic deep chondrocytes expressing Collagen X. The type V tissue had a composition similar to that of the normal articular hyaline cartilage with a predominance of collagen Ⅱ B and abundant glycosaminoglycans. These five types seemed to indicate the different stages of osteophyte development： mesenchymal cell, prechondrocyte, chondrocyte, early osteophyte and mature osteophyte. Immunohistochemistry showed that the expression level of insulinlike growth factor- I in the type I tissue was 14.6 ± 3.8, significantly higher than those in the types IV and V tissues （7.7 ± 3.5 and 6. 0 ± 1.9 respectively, both P = 0. 000 ） ; and the expression level of insulinlike growth factor- I in the type Ⅱtissue was 13.6 ±4.7, significantly higher than those in the types IV and Vtissues （ both P = 0.000）. The results of in situ hybridization were similar to those by imunohistochemistry. Conclusion Insulinlike growth factor-I mRNA is mainly expressed in the early stage osteophyte, and it may play an important role in initiation of the chondrogenic differentiation of mesenchymal progenitor cells in the early stage of osteophyte development.