Yamate T, Kohri K, Umekawa T, Amasaki N, Amasaki N, Isikawa Y, Iguchi M, Kurita T
Department of Urology, Kinki University School of Medicine, Osaka, Japan.
Eur Urol. 1996;30(3):388-93. doi: 10.1159/000474201.
We have recently reported that osteopontin protein (OPN) is present in calcium-containing urinary calculi and in rat distal tubular cells and that it is an important substance of the matrix in urinary stone formation. To investigate how OPN participates in urinary stone formation, we assessed the role of OPN in the adhesion of the surfaces of Madin-Darby canine kidney (MDCK) cells, which are distal tubular cells of the dog, to calcium oxalate crystals.
We cultured MDCK cells with OPN, thrombin, which is an OPN inhibitor, Arg-Gly-Asp peptide and Arg-Gly-Glu peptide as a control for Arg-Gly-Asp peptide, and examined changes in adhesion of calcium oxalate crystals to the cells by scanning electron microscopy and the calcium (45Ca) concentration around the cells.
The 45Ca concentration in calcium oxalate crystals adhering to MDCK cells was about 1.4 times higher in MDCK cells incubated with OPN than in an MDCK-cell-negative group, and was about one half that in MDCK cells incubated with thrombin than in the group without MDCK cells.
OPN is considered to be an accelerator of urinary stone formation because of the increase in adhesion of calcium oxalate crystals to the renal distal tubular epithelium in the presence of OPN. These findings suggest that OPN plays an important role in the formation of calcium-containing urinary stones.
我们最近报道骨桥蛋白（OPN）存在于含钙尿路结石及大鼠远端肾小管细胞中，且它是尿路结石形成过程中基质的一种重要物质。为研究OPN如何参与尿路结石形成，我们评估了OPN在犬肾上皮细胞（MDCK）（犬的远端肾小管细胞）表面与草酸钙晶体黏附过程中的作用。
我们用OPN、凝血酶（一种OPN抑制剂）、精氨酸 - 甘氨酸 - 天冬氨酸肽（Arg - Gly - Asp肽）以及作为Arg - Gly - Asp肽对照的精氨酸 - 甘氨酸 - 谷氨酸肽（Arg - Gly - Glu肽）培养MDCK细胞，通过扫描电子显微镜检查草酸钙晶体与细胞黏附的变化以及细胞周围的钙（45Ca）浓度。
与OPN共同孵育的MDCK细胞上黏附的草酸钙晶体中的45Ca浓度，比MDCK细胞阴性组高约1.4倍，而与凝血酶共同孵育的MDCK细胞中的45Ca浓度，比无MDCK细胞组低约一半。
由于在OPN存在的情况下草酸钙晶体与肾远端肾小管上皮的黏附增加，OPN被认为是尿路结石形成的促进因子。这些发现表明OPN在含钙尿路结石的形成中起重要作用。
