Zhenwu Decoction Alleviates Renal Fibrosis by Disrupting the Bidirectional Crosstalk Between TGF-β/Smad and Notch Signaling.

Zhenwu Decoction (ZWD) is a traditional Chinese medicine prescription with well-documented renoprotective effects, though its precise mechanism of action against renal fibrosis remains to be elucidated. This study aimed to explore whether ZWD mitigates renal fibrosis by modulating the loop of transforming growth factor-β (TGF-β)/Smad and Notch signaling pathways. In vivo and in vitro experiments were conducted using unilateral ureteral obstruction (UUO) rat models and TGF-β1-stimulated NRK-49F fibroblast cells, respectively. The study's findings revealed that ZWD significantly improved renal function, mitigated pathological damage, and decreased extracellular matrix deposition in UUO rats. Treatment with ZWD led to a marked downregulation of TGF-β1, Notch1, and Jagged1 expression, as well as a reduction in Smad2/3 phosphorylation, both in vivo and in vitro. Gain- and loss-of-function experiments demonstrated that overexpression of TGF-β1 enhanced Notch signaling, whereas TGF-β1 knockdown inhibited it. Similarly, Notch1 overexpression increased TGF-β/Smad signaling, while Notch1 silencing suppressed TGF-β/Smad activity, thus confirming the existence of a positive bidirectional feedback loop in the context of renal fibrosis. Importantly, Notch1 overexpression directly induced a fibrotic phenotype in NRK 49F cells. In summary, the TGF-β/Smad and Notch pathways constitute a bidirectional positive feedback loop that promotes renal fibrosis. ZWD alleviates renal fibrosis by disrupting this crosstalk, highlighting its potential as a therapeutic strategy for chronic kidney disease (CKD).