Abstract：
Diabetic nephropathy (DN) is a common complication of diabetes, characterized by renal fibrosis and poor patient prognosis. Hederagenin (HDG) has shown promising improvement in chronic kidney disease (CKD) kidney fibrosis, but its mechanism in DN-induced kidney fibrosis remains unclear. In this study, a model of diabetic nephropathy (DN) in mice was induced by intraperitoneal injection of streptozocin (50 mg/kg), while in vitro, high glucose (25 mM) was used to induce HK2 cell damage, simulating tubular injury in DN kidneys. The improvement of HDG treatment intervention was evaluated by observing changes in renal function, pathological structural damage, and the expression of fibrosis-related proteins in renal tubular cells. The results demonstrate that HDG intervention alleviates renal dysfunction and pathological damage in DN mice, accompanied by reduced expression of fibrotic markers α-smooth muscle actin (α-SMA), fibronectin (FN) and Collagen-I. Mechanistically, this study found that HDG can inhibit ferroptosis and fibrosis induced by the ferroptosis inducer Erastin (1 μM) in renal tubular cells. Phosphorylation of Smad3 promotes ferroptosis in renal tubular cells. After using its specific inhibitor SIS3 (4 μM), the expression of downstream target protein NADPH oxidase 4 (NOX4) significantly decreases, while the level of glutathione peroxidase 4 (GPX4) is notably restored, mitigating ferroptosis. Smad3 overexpression attenuates the therapeutic effect of HDG on tubular cell fibrosis induced by high glucose. These results demonstrate HDG inhibits Smad3 phosphorylation, thereby reducing the expression of NOX4 and enhancing the expression of GPX4, ultimately attenuating ferroptosis induced renal fibrosis. These findings suggest that HDG offer therapeutic potential for DN renal fibrosis by targeting Smad3-mediated ferroptosis in renal tubular cells.
摘要：
糖尿病肾病(DN)是糖尿病的常见并发症,以肾脏纤维化和患者预后不良为特征。Hederagenin（HDG）在慢性肾脏病（CKD）肾脏纤维化中显示出有希望的改善，但其在DN诱导的肾纤维化中的作用机制尚不清楚。在这项研究中,通过腹腔注射链脲佐菌素（50mg/kg）诱导小鼠糖尿病肾病（DN）模型，而在体外，高葡萄糖（25mM）用于诱导HK2细胞损伤，模拟DN肾脏的肾小管损伤。通过观察肾功能的变化来评估HDG治疗干预的改善情况。病理性结构损伤，和纤维化相关蛋白在肾小管细胞中的表达。结果表明，HDG干预减轻了DN小鼠的肾功能损害和病理损伤，伴有纤维化标志物α-平滑肌肌动蛋白（α-SMA）表达降低，纤连蛋白（FN）和胶原蛋白I.机械上,这项研究发现，HDG可以抑制铁凋亡诱导剂Erastin（1μM）在肾小管细胞中诱导的铁凋亡和纤维化。Smad3的磷酸化促进肾小管细胞的铁凋亡。使用其特异性抑制剂SIS3（4μM）后，下游靶蛋白NADPH氧化酶4(NOX4)的表达显著降低,而谷胱甘肽过氧化物酶4（GPX4）的水平显着恢复，减轻铁性凋亡。Smad3过表达减弱HDG对高糖诱导的肾小管细胞纤维化的治疗作用。这些结果表明HDG抑制Smad3磷酸化，从而降低NOX4的表达，增强GPX4的表达，最终减轻铁性凋亡诱导的肾纤维化。这些发现表明，HDG通过靶向Smad3介导的肾小管细胞铁凋亡为DN肾纤维化提供治疗潜力。
