Oxysophoridine inhibits oxidative stress and inflammation in hepatic fibrosis via regulating Nrf2 and NF-κB pathways

Background: Hepatic fibrosis (HF) runs through multiple stages of liver diseases and promotes these diseases progression. Oxysophoridine (OSR), derived from Sophora alopecuroides l., is a bioactive alkaloid that has been reported to antagonize alcoholic hepatic injury. However, whether OSR suppresses HF and the mechanisms involved in Nrf2 remain unknown. Purpose: Since the dysregulation of inflammation and oxidative stress is responsible for the excessive accumulation of extracellular matrix (ECM) and fibrosis in the liver. We hypothesized that OSR may attenuate HF by inhibiting inflammation and oxidative stress through activating Nrf2 signaling. Methods: In this study, we employed LPS-stimulated HSC-T6 cells, RAW264.7 cells, and a CCl4-induced C57BL/6 mouse fibrotic model to evaluate its suppressing inflammation and oxidative stress, as well as fibrosis. Results: The result showed that OSR significantly reduced alpha-SMA and TGF-beta 1 at a low dose of 10 mu M in vitro and at a dose of 50 mg/kg in vivo, which is comparable to Silymarin, the only Chinese herbal active ingredient that has been marketed for anti-liver fibrosis. Moreover, OSR effectively suppressed the expression of iNOS at a dose of 10 mu M and COX-2 at a dose of 40 mu M, respectively. Furthermore, OSR demonstrated inhibitory effects on the IL-1 beta, IL-6, and TNF-alpha in vitro and almost extinguished cytokine storm in vivo. OSR exhibited antioxidative effects by reducing MDA and increasing GSH, thereby protecting the cell membrane against oxidative damage and reducing LDH release. Moreover, OSR effectively upregulated the protein levels of Nrf2, HO-1, and p62, but decreased pNF-kappa B p65, p-I kappa B alpha, and Keap1. Alternatively, mechanisms involved in Nrf2 were verified by siNrf2 interference, siNrf2 interference revealed that the anti-fibrotic effect of OSR was attributed to its activation of Nrf2.