Barth K, Bläsche R, Kasper M
Institute of Anatomy, Medical Faculty Carl Gustav Carus, Dresden University of Technology, Fiedlerstr. 42, 01307 Dresden, Germany.
Histochem Cell Biol. 2006 Nov;126(5):563-73. doi: 10.1007/s00418-006-0192-3. Epub 2006 May 30.
Immunohistochemical and in vitro studies indicate that caveolin-1, which occurs abundantly in alveolar epithelial type I cells and microvascular endothelial cells of the lung, is selectively downregulated in the alveolar epithelium following exposure to bleomycin. Bleomycin is also known to enhance the expression levels of metalloproteinases and of the metalloproteinase inducer CD147/EMMPRIN in lung cells. Experimental in vitro data has showed that MMP-inducing activity of CD147 is under the control of caveolin-1. We studied the effects of bleomycin on the expression of caveolin-1, CD147 and metalloproteinases using an alveolar epithelial rat cell line R3/1 with properties of both alveolar type I and type II cells and explanted rat lung slices. In parallel, retrospective samples of bleomycin-induced fibrosis in rats and mice as well as samples of wild type and caveolin-1 knockout animals were included for immunohistochemical comparison with in vitro data. Here we report that treatment with bleomycin downregulates caveolin-1 and increases CD147 and MMP-2 and -9 expression/activity in R3/1 cells using RT-PCR, Western blot analysis, MMP-2 activity assay and immunocytochemistry. Immunofluorescence double labeling revealed that caveolin-1 and CD147 were not colocalized in vitro. The in vitro findings were confirmed through immunohistochemical studies of the proteins in paraffin embedded precision-cut rat lung slices and in fibrotic rat lung tissues. The caveolin-1-negative hyperplastic ATII cells exhibited enhanced immunoreactivity for CD147 and MMP-2. Caveolin-1-negative ATI cells of fibrotic samples were mostly CD147 negative. There were no differences in the pulmonary expression of CD147 between the normal and caveolin-1 deficient animals. The results demonstrate that bleomycin-induced lung injury is associated with an increase in CD147 expression and MMP activity, particularly in alveolar epithelial cells. In addition, our data exclude any functional interaction between CD147 and alveolar epithelial caveolin-1.
免疫组织化学和体外研究表明，在肺泡I型上皮细胞和肺微血管内皮细胞中大量存在的小窝蛋白-1，在博来霉素暴露后，在肺泡上皮中被选择性下调。博来霉素还已知可增强肺细胞中金属蛋白酶和金属蛋白酶诱导剂CD147/EMMPRIN的表达水平。体外实验数据表明，CD147的MMP诱导活性受小窝蛋白-1的控制。我们使用具有肺泡I型和II型细胞特性的肺泡上皮大鼠细胞系R3/1和离体大鼠肺切片，研究了博来霉素对小窝蛋白-1、CD147和金属蛋白酶表达的影响。同时，纳入了博来霉素诱导的大鼠和小鼠肺纤维化回顾性样本以及野生型和小窝蛋白-1基因敲除动物的样本，用于与体外数据进行免疫组织化学比较。在此我们报告，使用逆转录聚合酶链反应（RT-PCR）、蛋白质免疫印迹分析、MMP-2活性测定和免疫细胞化学方法，博来霉素处理可下调R3/1细胞中的小窝蛋白-1，并增加CD147以及MMP-2和-9的表达/活性。免疫荧光双标记显示，小窝蛋白-1和CD147在体外不共定位。通过对石蜡包埋的精密切割大鼠肺切片和纤维化大鼠肺组织中蛋白质的免疫组织化学研究，证实了体外研究结果。小窝蛋白-1阴性的增生性II型肺泡上皮细胞对CD147和MMP-2的免疫反应性增强。纤维化样本中，小窝蛋白-1阴性的I型肺泡上皮细胞大多为CD147阴性。正常动物和小窝蛋白-1缺陷动物之间，肺组织中CD147的表达没有差异。结果表明，博来霉素诱导的肺损伤与CD147表达增加和MMP活性增加有关，特别是在肺泡上皮细胞中。此外，我们的数据排除了CD147与肺泡上皮小窝蛋白-1之间的任何功能相互作用。
