目的  观察转化生长因子β1（TGF-β1）对CCAAT增强子结合蛋白α（C/EBPα）、过氧化物酶增殖物激活受体γ（PPARγ）核转录因子表达的影响，探讨C/EBPα在TGF-β1致肾间质纤维化过程中的表达及其机制。方法  体外培养人肾小管上皮细胞（HK-2），利用TGF-β1分别在不同质量浓度（5 和10 ng/mL）和不同时间点（0、4、12、24 h）刺激HK-2细胞，收集细胞总RNA和蛋白（核蛋白和总蛋白）以及细胞上清液。应用real-time PCR法和Western blotting检测C/EBPα和核转录因子PPARγ以及上皮细胞-间充质转化(EMT)相关蛋白α-SMA、E-cadherin的表达变化； ELISA方法检测细胞上清液中单核细胞趋化蛋白1（MCP-1）的表达水平。结果  TGF-β1（5 ng/mL）刺激HK-2细胞 24 h后C/EBPα蛋白与PPARγ变化一致，差异均无统计学意义（P>0.05 ）;E-cadherin表达减少。TGF-β1（10 ng/mL）分别刺激0、4、12、24 h后，核蛋白中C/EBPα在12 h时表达明显降低，PPARγ在4 h表达升高。以TGF-β1 10 ng/mL刺激HK-2细胞12 h后，C/EBPα、PPARγ、E-cadherin mRNA分别降低70%、50%和90%（P<0.05）。以10 ng/mL TGF-β1刺激HK-2细胞后，MCP-1在12、24 h时分别升高6倍和10.67倍。结论  C/EBPα参与TGF-β1诱导的肾间质纤维化过程，并且与间质纤维化过程中的炎症反应和EMT过程相关；且在此过程中，与PPARγ相互作用，促进或抑制肾间质纤维化。

Objective  To observe the effect of transforming growth factor β1(TGF-β1) on expressions of CCAAT enhancer binding protein α (C/EBPα) and nuclear transcription factors of peroxisome proliferator-activated receptor γ (PPARγ) and explore the expression of C/EBPα in the process of TGF-β1 induced renal fibrosis and relevant mechanisms. Methods  Human renal tubular epithelial cells (HK-2) were cultured in vitro and stimulated by TGF-β1 of different concentrations (5 and 10 ng/mL) at different time points (0, 4, 12, and 24 h). Total RNA and protein (nucleoprotein and total protein) and supernatant were collected. Changes of expressions of C/EBPα, nuclear transcription factor PPARγ, and epithelial-mesenchymal transition (EMT) related proteins α-SMA and E-cadherin were detected by real-time PCR and Western blotting. The expression level of monocyte chemotactic protein 1(MCP-1) in supernatant was detected by ELISA. Results  The change of C/EBPα level was the same as that of PPARγ level after HK-2 cells were stimulated by TGF-β1 (5 ng/mL) for 24 h. The difference was not statistically significant (P>0.05) and the expression of E-cadherin decreased. The expression of C/EBPα in nucleoprotein decreased remarkably at 12 h and the expression of PPARγ increased at 4 h after HK-2 cells were stimulated by TGF-β1 (10 ng/mL) for 0, 4, 12, and 24 h. The mRNA expressions of E-cadherin, C/EBPα, and PPARγ decreased by 70%, 50%, and 90%, respectively after HK-2 cells were stimulated by TGF-β1 (10 ng/mL) for 12 h (P<0.05). The MCP-1 level increased by 6 and 10.67 times at 12 h and 24 h after HK-2 cells were stimulated by TGF-β1 (10 ng/mL). Conclusion  C/EBPα involves in the renal interstitial fibrosis induced by TGF-β1 and is relevant to inflammatory response and EMT process of the renal interstitial fibrosis.  C/EBPα also interacts with PPARγ and enhances or inhibits the renal interstitial fibrosis.