目的

探讨表没食子儿茶素没食子酸酯（epigallocatechin gallate， EGCG）对小鼠急性肾损伤（acute kidney injury，AKI）的保护作用及机制。

方法

采用单侧肾缺血再灌注建立AKI 小鼠模型，30 只8 ～10 周龄C57BL/6J 小鼠被随机分为假手术组、AKI 模式溶剂组（连续3 d 腹腔注射等体积生理盐水）、AKI 模式EGCG 低剂量组（连续3 d 腹腔注射6.25 mg/kg EGCG）、AKI 模式EGCG 中剂量组（连续3 d 腹腔注射12.5 mg/kg EGCG）和AKI 模式EGCG 高剂量组（连续3 d 腹腔注射25 mg/kg EGCG），每组均6 只。 干预3 d后取材，检测血清肌酐、血尿素氮评估肾功能；肾组织PAS 染色评估肾小管损伤程度；Western 印迹和PCR 法检测肾脏的肾损伤标志物、细胞周期相关衰老标志物及衰老相关分泌表型的表达水平；肾脏组织β-半乳糖苷酶染色观察细胞衰老情况。

结果

与假手术组相比，AKI 模式溶剂组小鼠的血清肌酐、血尿素氮水平较高、肾小管损伤加重（P 均＜0.05）。 与AKI 模式溶剂组相比，AKI 模式EGCG 中剂量组小鼠的血清肌酐、血尿素氮水平较低，肾小管损伤程度也较轻（P 均＜0.05）；而AKI 模式EGCG 低剂量组和AKI 模式EGCG 高剂量组小鼠的上述指标未见改善。 此外，与AKI 模式溶剂组相比，AKI 模式EGCG 中剂量组小鼠肾脏的肾损伤标志物、细胞周期相关衰老标志物、及衰老相关分泌表型的表达水平下调（P 均＜0.05），β-半乳糖苷酶染色的阳性面积亦显著减少（P ＜0.05）。

结论

中剂量（12.5 mg/kg）的EGCG 能有效减轻小鼠单侧肾缺血再灌注AKI，其保护机制可能与抑制肾小管细胞衰老有关。

Objective

To explore the protective effect and mechanism of epigallocatechin gallate（EGCG） on acute kidney injury （AKI） in mice.

Methods

An AKI model of renal unilateral ischemiareperfusion injury was established in mice.Thirty C57BL/6J mice aged 8-10 weeks were randomly divided into sham operation group， AKI mode solvent group （intraperitoneal injection of equal volume saline for 3 consecutive days）， AKI mode EGCG low-dose group （intraperitoneal injection of 6.25 mg/kg EGCG for 3 consecutive days），AKI mode EGCG medium-dose group （intraperitoneal injection of 12.5 mg/kg EGCG for 3 consecutive days），and AKI mode EGCG high-dose group （intraperitoneal injection of 25 mg/kg EGCG for 3 consecutive days）， with 6 mice in each group.After 3 days of the intervention， samples were taken to measure serum creatinine （Scr） and blood urea nitrogen （BUN） to evaluate renal function， while periodic acid-Schiff staining of renal tissue was used to evaluate the degree of renal tubular injury.Western blot and PCR were used to detect the expression levels of renal injury markers， cell cycle-related senescence markers， and senescence-associated secretory phenotypes.Observation of cellular senescence was performed with β-galactosidase staining in renal tissues.

Results

Compared with the sham operation group， the AKI mode solvent group showed significantly elevated levels of Scr and BUN， as well as more severe renal tubular injury （all P ＜0.05）.Compared with the AKI mode solvent group， the AKI mode EGCG medium-dose group exhibited significantly reduced levels of Scr and BUN， and reduced degree of renal tubular injury （all P ＜0.05）.In contrast， both the AKI mode EGCG low-dose group and the AKI mode EGCG high-dose group did not show any improvement in the above indicators.Additionally， compared with the AKI mode solvent group， the AKI mode EGCG medium-dose group also displayed significantly downregulated expression levels of renal injury markers， cell cycle-related senescence markers， and senescence-associated secretory phenotypes （all P ＜0.05）， and the positive area of β-galactosidase staining was also reduced apparently （P ＜0.05）.

Conclusion

Medium dose （12.5 mg/kg） of EGCG could effectively alleviate the renal unilateral ischemia-reperfusion AKI in mice， and its protective mechanism might be related to the inhibition of the renal tubular senescence.