Silibinin Augments the Antifibrotic Effect of Valsartan Through Inactivation of TGF-β1 Signaling in Kidney

Background: Chronic kidney disease (CKD) has become a major public health issue. Meanwhile, renal fibrosis caused by diabetic nephropathy can lead to CKD, regardless of the initial injury. It has been previously reported that silibinin or valsartan could relieve the severity of renal fibrosis. However, the effect of silibinin in combination with valsartan on renal fibrosis remains unclear. Material and Methods: Proximal tubular cells (HK-2) were treated with TGF-beta 1 (5 ng/mL) to mimic in vitro model of fibrosis. The proliferation of HK-2 cells was tested by CCK-8. Epithelial-mesenchymal transition (EMT) and inflammation-related gene and protein expressions in HK-2 cells were measured by qRT-PCR and Western-blot, respectively. ELISA was used to test the level of TNF-alpha NF-A. Additionally, HFD-induced renal fibrosis mice model was established to investigate the effect of silibinin in combination with valsartan on renal fibrosis in vivo. Results: Silibinin significantly increased the anti-fibrosis effect of valsartan in TGF-beta 1-treated HK-2 cells via inhibition of TGF-beta 1 signaling pathway. Furthermore, silibinin significantly enhanced the anti-fibrosis effect of valsartan on HFD-induced renal fibrosis in vivo through inactivation of TGF-beta 1 signaling pathway. Conclusion: These data indicated that silibinin markedly increased anti-fibrosis effect of valsartan in vitro and in vivo. Thus, silibinin in combination with valsartan may act as a potential novel strategy to treat renal fibrosis caused by diabetic nephropathy.