TLR4 and renal fibrosis: Astragaloside IV may potentially protect against renal fibrosis by reducing oxidative stress and inflammation via transforming growth factor-β1 (TGF-β1)/Smads signaling or the toll-like receptor 4 (TLR4)/nuclear factor kappa-B (NF-κB) signaling pathway (Gui et al., 2013; Zhou et al., 2017b; Du et al., 2018).