Diabetic nephropathy (DN) seriously affects the people's life and health in China. This study aimed to investigate the effect of circRNA circ-ITCH on improving DN by regulating the miR-33a-5p/SIRT6 axis and the possible mechanism of action. High glucose (HG)-induced rat mesangial cells (RMCs) were used to simulate the DN in vitro. Reverse transcription-quantitative PCR (RT-qPCR) and western blot analysis were conducted to detect the gene or protein expression. Cell Counting Kit-8 (CCK-8) and wound healing assays were performed to estimate the cell viability and migration capability. Immunofluorescence and enzyme-linked immunosorbent assay (ELISA) were used to detect the α-Smooth Muscle Actin (α-SMA) expression and levels of inflammatory factors. The potential associations between circ-ITCH and miR-33a-5p, miR-33a-5p and SIRT6 in RMCs were measured via dual-luciferase reporter assay. Streptozotocin (STZ) was used to induce the diabetic mice. Blood glucose and serum insulin of mice were determined by corresponding kits, and blood urea nitrogen (BUN) and serum creatinine (SCr) were measured using an automatic biochemical analyzer. Hematoxylin and eosin (H&E) staining and periodic acid-Schiff (PAS) staining were applied to observe the degree of pathological injury and fibrosis of renal tissues. The results of the present study revealed that circ-ITCH expression was obviously decreased in HG-induced RMCs. In addition, circ-ITCH overexpression inhibited the viability, migration, fibrosis and inflammatory response of HG-induced RMCs. Further experiments confirmed that miR-33a-5p may be a direct target of circ-ITCH and SIRT6 may be a direct target of miR-33a-5p. Notably, the miR-33a-5p mimic or shRNA-SIRT6 were discovered to reverse the inhibitory effects of circ-ITCH on the proliferation, migration, fibrosis and inflammatory response of HG-induced RMCs. Furthermore, circ-ITCH overexpression ameliorated renal inflammation and fibrosis in STZ-induced diabetic mice. In conclusion, circ-ITCH alleviated renal inflammation and fibrosis in STZ-induced diabetic mice by regulating the miR-33a-5p/SIRT6 axis.Author names: Please confirm if the author names are presented accurately and in the correct sequence (given name, middle name/initial, family name). Author 1 Given name: [ChunYang] Last name [Xu]. Author 2 Given name: [DingBo] Last name [Xu]. Author 3 Given name: [YongHua] Last name [Liu]. Author 4 Given name: [Juanjuan] Last name [Jiang]. Also, kindly confirm the details in the metadata are correct.ok

糖尿病肾病（DN）严重影响着我国人民的生命健康。本研究旨在探讨circRNA circ-ITCH通过调节miR-33a-5p/SIRT6轴改善DN的作用及可能的作用机制。高糖 (HG) 诱导的大鼠系膜细胞 (RMC) 用于在体外模拟 DN。进行逆转录-定量PCR（RT-qPCR）和蛋白质印迹分析以检测基因或蛋白质表达。进行细胞计数试剂盒-8 (CCK-8) 和伤口愈合试验以估计细胞活力和迁移能力。免疫荧光和酶联免疫吸附试验（ELISA）用于检测α-平滑肌肌动蛋白（α-SMA）的表达和炎症因子的水平。circ-ITCH 和 miR-33a-5p 之间的潜在关联，通过双荧光素酶报告基因测定测量 RMC 中的 miR-33a-5p 和 SIRT6。链脲佐菌素（STZ）用于诱导糖尿病小鼠。采用相应试剂盒测定小鼠血糖和血清胰岛素，采用全自动生化分析仪测定血尿素氮（BUN）和血清肌酐（SCr）。应用苏木精伊红(H&E)染色和过碘酸-希夫(PAS)染色观察肾组织病理损伤和纤维化程度。本研究的结果表明，HG 诱导的 RMC 中 circ-ITCH 表达明显降低。此外，circ-ITCH 过表达抑制了 HG 诱导的 RMC 的活力、迁移、纤维化和炎症反应。进一步的实验证实，miR-33a-5p 可能是 circ-ITCH 的直接靶点，而 SIRT6 可能是 miR-33a-5p 的直接靶点。值得注意的是，miR-33a-5p 模拟物或 shRNA-SIRT6 被发现可以逆转 circ-ITCH 对 HG 诱导的 RMC 的增殖、迁移、纤维化和炎症反应的抑制作用。此外，circ-ITCH 过表达改善了 STZ 诱导的糖尿病小鼠的肾脏炎症和纤维化。总之，circ-ITCH 通过调节 miR-33a-5p/SIRT6 轴减轻了 STZ 诱导的糖尿病小鼠的肾脏炎症和纤维化。中间名/首字母，姓）。作者 1 名：[春阳] 姓 [徐]。作者 2 名：[丁博] 姓 [徐]。作者 3 名字：【永华】姓【刘】。作者 4 名：【娟娟】 姓【江】。另外，请确认元数据中的详细信息是正确的。ok