BACKGROUND Dihydroquercetin (DHQ) is an antifibrotic agent. However, whether DHQ can prevent renal fibrosis remains unknown. PURPOSE This study aimed to investigate the effects of DHQ on tubulointerstitial fibrosis and its underlying mechanisms in unilateral ureteral obstruction (UUO) mice in vivo and NRK-49F cells in vitro. METHODS In vivo, UUO mice received vehicle or DHQ treatment. In vitro, NRK-49F cells were pretreated with DHQ and exposed to transforming growth factor-β1 (TGF-β1). Changes in fibroblast activation, collagen synthesis, oxidative stress, and related signaling pathways were assessed by immunohistochemical staining, Western blot analysis, real-time reverse transcription-PCR, and fluorescence microscopy. RESULTS UUO induced tubular atrophy, inflammation, fibroblast differentiation into myofibroblast, and collagen deposition, whereas DHQ ameliorated these effects. UUO also resulted in decreased levels of nuclear factor-erythroid-2-related factor 2 (Nrf2), catalase, and heme oxygenase-1, but increased H2O2 and malondialdehyde levels. DHQ treatment corrected these changes. In vitro, the intracellular Nrf2 level of NRK-49F exposed to TGF-β1 decreased. However, DHQ rescued intracellular Nrf2 level and promoted nuclear translocation of Nrf2. DHQ scavenged TGF-β1-induced accumulation of reactive oxygen species, inhibited TGF-β1-induced Smad3 phosphorylation, and prevented TGF-β1-induced fibroblast activation and collagen synthesis in NRK-49F. Nrf2 knockdown could suppress the DHQ-mediated inhibitory effects on oxidative stress, Smad3 phosphorylation, fibroblast activation, and collagen deposition. Furthermore, DHQ ameliorated established renal fibrosis in UUO mice. CONCLUSIONS DHQ posed remarkable preventive and therapeutic effects on UUO-induced renal fibrosis and suppressed fibroblast activation by reducing oxidative stress and Smad3 phosphorylation via Nrf2 signaling. This study provided a mechanistic basis for the clinical application of DHQ in renal fibrosis treatment.

中文翻译：

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二氢槲皮素可通过激活Nrf2途径来防止肾脏纤维化。

背景技术二氢槲皮素（DHQ）是抗纤维化剂。但是，DHQ是否可以预防肾纤维化尚不清楚。目的本研究旨在研究DHQ对单侧输尿管梗阻（UUO）小鼠体内和体外NRK-49F细胞的肾小管间质纤维化的影响及其潜在机制。方法在体内，UUO小鼠接受载体或DHQ处理。在体外，用DHQ预处理NRK-49F细胞，并使其暴露于转化生长因子-β1（TGF-β1）。通过免疫组织化学染色，蛋白质印迹分析，实时逆转录PCR和荧​​光显微镜评估成纤维细胞活化，胶原蛋白合成，氧化应激和相关信号通路的变化。结果UUO引起肾小管萎缩，炎症，成纤维细胞分化为成肌纤维细胞和胶原沉积，DHQ改善了这些影响。UUO还导致核因子-类胡萝卜素2相关因子2（Nrf2），过氧化氢酶和血红素加氧酶-1水平降低，但过氧化氢和丙二醛水平升高。DHQ治疗纠正了这些变化。在体外，暴露于TGF-β1的NRK-49F的细胞内Nrf2水平降低。但是，DHQ挽救了细胞内Nrf2的水平并促进了Nrf2的核易位。DHQ清除了NRK-49F中TGF-β1诱导的活性氧的积累，抑制TGF-β1诱导的Smad3磷酸化并阻止TGF-β1诱导的成纤维细胞活化和胶原合成。Nrf2组合式可以抑制DHQ介导的对氧化应激，Smad3磷酸化，成纤维细胞活化和胶原蛋白沉积的抑制作用。此外，DHQ改善了UUO小鼠的既定肾脏纤维化。结论DHQ通过减少氧化应激和Smad3磷酸化（通过Nrf2信号传导）对UUO诱导的肾纤维化具有显着的预防和治疗作用，并抑制了成纤维细胞的活化。该研究为DHQ在肾纤维化治疗中的临床应用提供了机械基础。