Schisandrin B targets cannabinoid 2 receptor in Kupffer cell to ameliorate CCl4-induced liver fibrosis by suppressing NF-κB and p38 MAPK pathway

Lignans, the major bioactive components of Schisandra chinensis, displays an anti-liver fibrosis effect. However, which one is the most effective lignan and what is its molecular mechanisms are still unclear.This research aimed to screen the most effective components of lignans, identify and verify its pharmacological target, and investigate its molecular mechanism against liver fibrosis.First, the most effective lignans were screened by a comprehensive RAW264.7/CMC system and LPS-induced RAW264.7. Second, the potential targets were predicted by a liver fibrosis domain-specific chemo-genomics knowledgebase and further verified by competition binding assay. Third, the effect of anti-liver fibrosis was evaluated by employing RAW264.7, co-cultured hepatic stellate cells (HSC) and CCl4-induced liver fibrosis CB2-/- mice. The qPCR, ELISAs, western blot analyses, and immunofluorescence were used to evaluate the expression of main inflammatory factors and key proteins in NF-κB and p38 MAPK pathway.Schisandrin B was identified as the most effective component for attenuating liver fibrosis, and CB2 was proven to be a potential target for anti-liver fibrosis. The in vitro and in vivo assays indicated that schisandrin B ameliorated CCl4-induced liver fibrosis through suppressing NF-κB and p38 MAPK pathway in Kupffer cells by targeting CB2 receptor CONCLUSION: Schisandrin B targets CB2 receptor to inhibit Kupffer cell polarization by downregulating the NF-κB and p38 MAPK signaling pathways for ameliorating liver fibrosis.