Compound Biejia-Ruangan tablets activate the STING-TBK1 pathway to alleviate hepatic fibrosis in alveolar echinococcosis.

UNLABELLED: Alveolar echinococcosis (AE) is a lethal parasitic disease that leads to progressive liver fibrosis, a process characterized by the dominance of M2 macrophages in advanced stages. While the compound Biejia-Ruangan tablet (CBRT) has demonstrated efficacy in reversing hepatic fibrosis, its underlying mechanisms in the context of AE-induced fibrosis are not fully understood. This study aimed to investigate the therapeutic potential of CBRT against AE-induced liver fibrosis and to elucidate its mechanisms of action. Serum levels of liver fibrosis markers and cytokines were measured by ELISA. Liver histopathology and collagen deposition were assessed using H&E and Masson's trichrome staining. Apoptosis in GHA1 hepatocytes was evaluated by flow cytometry. Macrophage migration was analyzed via scratch and Transwell invasion assays. The involvement of the STING-TBK1 signaling pathway was examined through western blotting (WB), immunohistochemistry (IHC), immunofluorescence (IF), and quantitative real-time PCR (qRT-PCR). Livers from Echinococcus multilocularis (E.m.)-infected mice exhibited severe fibrosis accompanied by significant infiltration of M2 macrophages and upregulated expression of STING-TBK1 pathway components (Arg-1, α-SMA, STING, and TBK1). Treatment with CBRT (1 g/kg) markedly attenuated liver fibrosis in vivo (P < 0.01) and inhibited the activation of mouse hepatic stellate cells (mHSCs) in vitro. CBRT suppressed the activation of HSCs, partly by upregulating IFN-γ, suppressed apoptosis in GHA1 hepatocytes, and improved hepatocyte function. Mechanistically, CBRT activates the STING-TBK1 signaling pathway, which subsequently suppresses the polarization of macrophages toward the M2 phenotype, thereby alleviating fibrogenesis. This study demonstrates that CBRT alleviates hepatic fibrosis by activating the STING-TBK1 signaling pathway. This activation elicits a shift in macrophage polarization from the pro-fibrotic M2 phenotype towards the M1 phenotype, which subsequently suppresses the activation of hepatic stellate cells and alleviates fibrogenesis. These findings reveal a novel immunomodulatory mechanism of CBRT centered on the STING-TBK1 axis, providing both experimental evidence and a theoretical foundation for its potential application in treating hepatic fibrosis associated with AE.

IMPORTANCE

This study demonstrates that compound Biejia-Ruangan tablet (CBRT) alleviates Echinococcus multilocularis (E.m.)-induced hepatic fibrosis by reactivating the suppressed STING-TBK1 signaling pathway in the chronic infection stage, thereby reprogramming macrophage polarization from a pro-fibrotic M2 phenotype toward an M1 phenotype. This work identifies CBRT as a promising immunomodulatory agent that can reverse the Th2/M2-dominated immunosuppressive microenvironment, providing a novel therapeutic strategy for AE and potentially other infection-associated fibrotic diseases. However, further research is required to validate the translational efficacy of CBRT and to define the precise therapeutic window for STING-TBK1 modulation in human fibrotic disorders.