Department of Nephrology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China.
Department of Urology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China.
J Transl Med. 2023 Aug 2;21(1):521. doi: 10.1186/s12967-023-04376-0.
Renal interstitial fibrosis is a common pathway for the progressive development of chronic renal diseases (CKD) with different etiology, and is the main pathological basis leading to end-stage renal disease. Although the current research on renal interstitial fibrosis is gradually deepening, the diagnosis and treatment methods are still very lacking. Uncoupling protein 1 (UCP1) is a nuclear encoded protein in mitochondria inner membrane and plays an important role in regulating energy metabolism and mitochondrial homeostasis. However, the biological significance of UCP1 and potential regulatory mechanisms in the development of CKD remain unclear.
Unilateral ureteral obstruction (UUO) model was used to construct the animal model of renal fibrosis, and TGF-β1 stimulation of HK2 cells was used to construct the vitro model of renal fibrosis. UCP1 expression was detected by Western blot, immunoblot analysis and immunohistochemistry. UCP1 was upregulated by UCP1 overexpressing lentivirus and UCP1 agonist CL316243. Western blot and immunofluorescence were used to detect epithelial mesenchymal transition (EMT)-related markers, such as collagen I, fibronectin, antioxidant enzyme SOD2 and CAT. Reactive oxygen species (ROS) production was detected by ROS detection kit. SIRT3 knockdown was performed by siRNA.
This study presents that UCP1 is significantly downregulated in patients with renal fibrosis and UUO model. Further studies discover that UCP1 overexpression and CL316243 treatments (UCP1 agonists) reversed EMT and extracellular matrix (ECM) accumulation in renal fibrosis models in vivo and in vitro. Simultaneously, UCP1 reduced the ROS production by increasing the stability of SIRT3. When SIRT3 was knocked down, the production of ROS decreased.
Elevating the expression of UCP1 can inhibit the occurrence of oxidative stress by stabilizing SIRT3, thereby reducing EMT and ECM accumulation, and ultimately alleviating renal interstitial fibrosis. It will provide new instructions and targets for the treatment of CKD.
肾间质纤维化是不同病因慢性肾脏病（CKD）进行性发展的共同通路，是导致终末期肾病的主要病理基础。虽然目前对肾间质纤维化的研究逐渐深入，但诊断和治疗方法仍非常缺乏。解偶联蛋白 1（UCP1）是线粒体内膜的核编码蛋白，在调节能量代谢和线粒体稳态中发挥重要作用。然而，UCP1 的生物学意义及其在 CKD 发展中的潜在调节机制尚不清楚。
采用单侧输尿管梗阻（UUO）模型构建肾纤维化动物模型，采用 TGF-β1 刺激 HK2 细胞构建肾纤维化体外模型。采用 Western blot、免疫印迹分析和免疫组织化学检测 UCP1 表达。通过 UCP1 过表达慢病毒和 UCP1 激动剂 CL316243 上调 UCP1。采用 Western blot 和免疫荧光检测细胞外基质（ECM）相关标志物如胶原 I、纤维连接蛋白、抗氧化酶 SOD2 和 CAT 的上皮间质转化（EMT）相关标志物。采用 ROS 检测试剂盒检测活性氧（ROS）的产生。通过 siRNA 进行 SIRT3 敲低。
本研究表明，UCP1 在肾纤维化患者和 UUO 模型中显著下调。进一步研究发现，UCP1 过表达和 CL316243 处理（UCP1 激动剂）逆转了体内和体外肾纤维化模型中的 EMT 和 ECM 积累。同时，UCP1 通过增加 SIRT3 的稳定性减少 ROS 的产生。当 SIRT3 被敲低时，ROS 的产生减少。
升高 UCP1 的表达可以通过稳定 SIRT3 抑制氧化应激的发生，从而减少 EMT 和 ECM 积累，最终缓解肾间质纤维化。这将为 CKD 的治疗提供新的指导和靶点。
