基于肝星状细胞BAMBI表达调节探讨甘草酸与黄芪总皂苷配伍抗肝纤维化的协同效应机制

Hepatic stellate cells (HSCs) express BMP and activin membrane-bound inhibitor (BAMBI), a TGF-β pseudoreceptor that can restrain the TGF-β signaling and prevent collagen overexpression. Activation of NF-κB in HSCs by proinflammatory stimuli has been found to reduce the cell expression of BAMBI, which enhances TGF-β-induced HSC activation and collagen production. We have demonstrated that astragalosides (AST) and glycyrrhizic acid (GA), the major effective components of Huangqi decoction, have a synergistic role against liver fibrosis. However, the synergistic anti-fibrotic mechanism of AST and GA has not been fully understood. Based on the inhibitory roles of AST and GA in TGFβ1 signaling and NF-κB signaling, respectively, we hypothesize that suppressing the NF-κB signaling and upregulating the expression of BAMBI in HSCs could be a major mechanism for GA and AST synergistically inhibiting TGF-β-induced HSC activation and collagen expression. We will use CCl4-induced liver fibrosis mouse model and cultured HSCs, and target BAMBI expression as well as the crosstalk between NF-κB and TGF-β signaling pathways, to reveal the synergistic mechanism of GA and AST in modulating HSC activation and collagen expression and deposition. The project will help understanding the approaches for utilizing in combination the effective components extracted from Chinese herb medicine to enhance the anti-fibrotic efficacy.

肝星状细胞（HSC）表达的骨形成蛋白和激活素跨膜抑制剂（BAMBI），作为TGF-β伪受体，可限制TGF-β信号通路的激活和胶原过度表达。促炎症因子激活NF-κB，可降低BAMBI表达，增强TGF-β诱导的HSC活化和胶原生成。我们已证实黄芪汤有效组分黄芪总皂苷（AST）和甘草酸（GA）配伍抗肝纤维化具有显著协同增效作用，但其配伍增效机制尚不明确。本课题基于AST和GA分别对TGF-β和NF-κB信号通路有抑制作用，提出“GA抑制肝星状细胞NF-κB活性并升高BAMBI表达，可能是与AST协同抑制TGF-β信号转导，减轻肝纤维化的主要机制”科学假说。拟以CCl4肝纤维化小鼠和人肝星状细胞株为研究对象，从BAMBI的表达调节与NF-κB和TGF-β信号通路的交互作用入手，阐释GA增强AST抑制HSC活化和胶原表达沉积的协同效应机制，为开发利用中药有效成分配伍，提高抗肝纤维化疗效提供科学依据。

肝损伤产生的促炎症因子通过激活NF-κB可降低肝星状细胞（HSC）表达骨形成蛋白和激活素跨膜抑制剂（BAMBI），从而增强TGF-β诱导的HSC活化和胶原过度生成与沉积，促进肝纤维化。课题组前期研究发现黄芪汤有效组分黄芪总皂苷（AS）和甘草酸（GA）配伍抗肝纤维化具有显著协同增效作用，但其配伍增效机制尚不明确。本课题基于AS和GA分别对TGF-β和NF-κB信号通路有抑制作用，提出“抑制肝星状细胞NF-κB活性并升高BAMBI表达，可能是GA与AS协同抑制TGF-β信号转导，减轻肝纤维化的主要机制”科学假说，并以二甲基亚硝胺（DMN）诱导的肝纤维化大鼠模型和人肝星状细胞为研究对象，旨在研究GA与AS调节NF-κB和TGF-β信号通路的交互作用及对BAMBI表达的影响，并揭示GA与AS配伍抑制HSC活化和胶原表达/沉积的协同效应机制。结果表明：（1）黄芪汤有效组分AS和GA改善DMN大鼠血清肝功能指标，减轻肝组织炎症和胶原沉积，AS和GA联用效果优于单用。（2）DMN造模后肝组织BAMBI表达下降，黄芪汤及有效组分AS和GA治疗能增加DMN大鼠BAMBI表达，以AS和GA联用效果最为显著。（3）AS和GA抑制肝星状细胞TGF-β/Smad信号通路的活化，联用效果优于单用。（4）AS和GA抑制肝星状细胞促炎症因子/NF-κB信号通路并升高BAMBI表达，AS和GA联用效果优于单用。这些结果表明AS和GA有效抑制DMN诱导的大鼠肝组织损伤和肝纤维化，其作用机理与抑制肝组织炎症反应信号通路和上调BAMBI表达有关，并揭示通过升高BAMBI表达抑制TGF/Smad信号通路和α-SMA及胶原表达是介导AS和GA抗肝纤维化配伍协同增效作用的关键环节。本研究揭示了黄芪汤有效组分AS和GA抗肝纤维化的新机制，为开发利用中药有效成分配伍，提高抗肝纤维化疗效提供新的科学依据。