Aims

Renal fibrosis is a progressive disease that leads to renal dysfunction and end-stage renal failure, and there is currently no specific treatment. Our previous study showed that the 8-residue peptide DR8 (DHNNPQIR) exhibits potent antioxidant and antifibrotic properties, and accumulating evidence suggests that oxidative stress contributes greatly to fibrosis. The effects and mechanisms of DR8 on renal fibrosis remain unknown.

Materials and methods

The effects of DR8 were assessed in a unilateral ureteral obstruction mouse model that received a daily, single-dose subcutaneous injection of 500 μg/kg DR8 for 14 days and in cultured cells (HK-2 and NIH-3T3 cells) treated with 5 ng/mL TGF-β1 and 80 μM DR8. Western blotting, immunohistochemical staining, real-time qPCR and other tools were conducted to study the molecular mechanisms underlying antifibrotic effects.

Key findings

DR8 improved renal function and reduced injury and extracellular matrix (ECM) deposition. Inflammation and oxidative stress were alleviated by DR8 in vivo. DR8 also inhibited the activation of fibroblasts and ECM deposition in HK-2 and NIH-3T3 cells induced by TGF-β1. In addition, epithelial-to-mesenchymal transition (EMT) was inhibited by DR8 both in vivo and in vitro. Mechanistic studies supported that DR8 inhibited ERK and p38 mitogen-activated protein kinase (MAPK) activation. These results indicate that DR8 attenuates renal fibrosis via suppression of EMT by antagonizing the MAPK pathway.

Significance

We provide mechanistic details for a potential therapeutic agent and establish a foundation for peptide therapeutics.

中文翻译：

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肽DR8通过TGF-β/ MAPK信号通路抑制肾纤维化中的上皮向间充质转化。

目的

肾纤维化是一种进行性疾病，可导致肾功能不全和终末期肾功能衰竭，目前尚无特异性治疗方法。我们先前的研究表明，8残基肽DR8（DHNNPQIR）具有强效的抗氧化和抗纤维化特性，并且越来越多的证据表明氧化应激在纤维化中起很大作用。DR8对肾纤维化的作用和机制尚不清楚。

材料和方法

在单侧输尿管阻塞小鼠模型中评估DR8的作用，该模型每天单次皮下注射500μg/ kg DR8，持续14天，并在5 ng处理的培养细胞（HK-2和NIH-3T3细胞）中进行评估/ mLTGF-β1和80μMDR8。进行了蛋白质印迹，免疫组化染色，实时定量PCR和其他工具来研究抗纤维化作用的分子机制。

主要发现

DR8改善了肾功能，减少了损伤和细胞外基质（ECM）沉积。DR8在体内可减轻炎症和氧化应激。DR8还抑制了TGF-β1诱导的HK-2和NIH-3T3细胞中成纤维细胞的活化和ECM沉积。另外，DR8在体内和体外均抑制上皮-间质转化（EMT）。机理研究支持DR8抑制ERK和p38丝裂原活化蛋白激酶（MAPK）活化。这些结果表明，DR8通过拮抗MAPK途径，通过抑制EMT来减轻肾纤维化。

意义

我们提供了潜在治疗剂的机械细节，并为肽治疗奠定了基础。