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.
Keywords: Dihydroquercetin; Nuclear factor-erythroid-2-related factor 2; Oxidative stress; Renal tubulointerstitial fibrosis.
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