目的 观察淫羊藿苷对5/6肾切除大鼠肾间质肌成纤维细胞增殖的影响，并探讨其作用机制。方法 将大鼠分为假手术组、模型组及淫羊藿苷高、低剂量（100、50 mg·kg^-1）组。假手术组仅分离肾包膜，模型组及淫羊藿苷高、低剂量组进行5/6肾切术，每组7只。术后第3周开始给药，每日1次。14周末留取大鼠血清，检测肌酐（Scr）、尿素氮（BUN）；取部分肾脏，苏木精-伊红（HE）染色法常规病理检查观察组织学改变；天狼星红染色检测肾间质纤维化；免疫组织化学法检测肾脏组织α-平滑肌肌动蛋白（α-SMΑ）、转化生长因子-β1（TGF-β1）、大鼠磷酸化信号转导分子2/3（p-SMAD2/3）、DNA甲基转移酶3A（Dnmt3a）的表达，另部分肾脏冻存，Western blotting检测α-SMA、TGF-β1、和Dnmt3a蛋白表达。结果 HE染色及天狼星红染色结果显示模型组大鼠肾小管扩张或萎缩，有大量纤维组织增生及胶原沉积，并见散在炎症细胞浸润。免疫组化结果显示模型组肌成纤维细胞标记物α-SMA表达明显升高，促纤维化因子TGF-β1及其下游分子p-Smad2/3表达明显增加；DNA甲基转移酶Dnmt3a表达明显升高。淫羊藿苷处理可以减轻肾脏病理损伤，抑制肌成纤维细胞异常增殖，改善肾间质纤维化，下调α-SMA、TGF-β1、p-Smad2/3和Dnmt3a表达。除淫羊藿苷高剂量组抑制Dnmt3a表达的效应强于淫羊藿苷低剂量组外，其余指标淫羊藿苷高剂量组和低剂量组效应差异不明显。结论 淫羊藿苷在5/6肾切除诱导的慢性肾病（CKD）大鼠中表现出抗纤维化作用，其机制可能是通过调控TGF-β1诱导的DNA高甲基化抑制肌成纤维细胞增殖，改善肾间质纤维化。

Objective To observe the effect of icariin on proliferation of renal interstitial myofibroblasts in 5/6 nephrectomized rats and explore its mechanism. Methods The rats were divided into sham operation group, model group, icariin high-dose group and icariin low-dose group. In the sham operation group, only the renal envelope was separated without nephrectomy, and the model group and icariin group underwent 5/6 nephrectomy, with seven rats in each group. Icariin was given 50 mg·kg^-1 in low-dose icariin group and 100 mg·kg^-1 in high-dose icariin group, once a day. The serum of rats was collected at the end of the 14th week to detect creatinine (Scr) and urea nitrogen (BUN). Part of the kidney was taken and histological changes were observed by routine pathological examination. Sirian red staining was used to detect renal interstitial fibrosis. The expressions of α-smooth muscle actin (α-SMΑ), transforming growth factor-β1 (TGF-β1), phospho-small mothers against decapentaplegic homolog 2/3 (p-SMAD2/3) and DNA methyltransferase 3A (Dnmt3a) in kidney tissues were detected by immunohistochemistry. The expressions of α -SMA, TGF- β1 and Dnmt3a in other kidney tissues were detected by Western blotting. Results HE and Sirius red staining showed that renal tubules in the model group were dilated or atrophied, with a large amount of fibrous tissue hyperplasia and collagen deposition, and scattered inflammatory cell infiltration. Immunohistochemical results showed that the expression of α -SMA, TGF- β1 and its downstream molecule p-Smad2/3 were significantly increased in the model group. The expression of DNA methyltransferase Dnmt 3a was significantly increased. Icariin treatment can alleviate renal pathological injury, inhibit abnormal proliferation of myofibroblasts, improve renal interstitial fibrosis, and down-regulate the expression of α-SMA, TGF-β1, p-Smad2/3 and Dnmt3a. The inhibitory effect of icariin high-dose group on Dnmt 3a expression was stronger than that of icariin low-dose group, but there was no significant difference in the effect of other indicators between icariin high-dose group and low-dose group. Conclusion Icariin shows an antifibrotic effect in 5/6 nephrectomy induced CKD rats, the mechanism may be through regulating TGF-β1- induced DNA hypermethylation to inhibit myofibroblasts proliferation and attenuate renal interstitial fibrosis.

R572;R363

天津市卫生健康科技项目（TJWJ2022MS050）