Abelmoschus manihot Polysaccharides Target the AMPK/Nrf2/HO-1 Signalling Pathway to Inhibit Macrophage M1 Polarisation and Hepatic Stellate Cell Activation Improving Liver Fibrosis in Mice.

Liver fibrosis (LF) is a critical pathological stage in the progression from chronic liver disease to cirrhosis. While Abelmoschus manihot polysaccharides (AMP) demonstrate hepatoprotective potential, the underlying anti-fibrotic mechanisms remain incompletely understood. A carbon tetrachloride-induced LF mouse model was established followed by AMP intervention. Comprehensive assessments included ELISA measurement of serum biochemical indicators (ALT, AST, ALP, TBA, TBil), fibrosis markers (HA, PC III, LN, Hyp) and inflammatory cytokines (IL-1β, TNF-α, IL-6, IL-10). Liver tissue pathological changes were evaluated through haematoxylin-eosin (HE), Masson and Sirius Red staining. In vitro experiments utilised TGF-β1-stimulated JS-1 and LPS/IFN-γ-induced M1-type RAW264.7 macrophages. Experimental techniques encompassed MTT assay, immunofluorescence, qPCR, Western blot and flow cytometry to analyse cellular markers and signalling pathways. The study specifically investigated AMP's regulatory effects on macrophage polarisation and hepatic stellate cell activation, using the AMPK inhibitor (Compound C) to explore potential mechanistic pathways. AMP treatment effectively mitigated CCl4-induced liver injury by reducing serum markers (ALT, AST, HA, PC III, Hyp) and pro-inflammatory cytokines (IL-1β, TNF-α, IL-6) while increasing anti-inflammatory IL-10. Mechanistically, AMP regulated macrophage polarisation (inhibiting M1 markers iNOS/CD80/CD86 while promoting M2 markers CD206/Arg-1) and suppressed fibrogenesis by downregulating α-SMA, Collagen I and TIMP1 while upregulating MMP13. These effects were mediated through activation of the AMPK/Nrf2/HO-1 pathway, ultimately inhibiting HSCs activation and extracellular matrix (ECM) accumulation. The AMPK inhibitor Compound C attenuates these protective effects. AMP alleviates LF by activating the AMPK/Nrf2/HO-1 pathway, modulating macrophage polarisation and ECM remodelling, demonstrating promising therapeutic potential.