Disruption of cholesterol homeostasis triggers NLRP3-cGAS-STING axis-dependent hepatic fibrosis and honokiol intervention effects

Background

Maintaining cholesterol homeostasis is crucial for sustaining human health and physiological function. Although the detrimental effects of chronic cholesterol overload on hepatic injury and fibrosis are well documented, the molecular mechanisms driving this pathology remain incompletely understood.

Purpose

This study investigates the mechanistic role of chronic cholesterol overload in driving liver fibrosis and evaluates the therapeutic efficacy of honokiol as a targeted intervention.

Study design and methods

High-cholesterol models induced by cholesterol and 25-hydroxycholesterol in human HepG2 cells or induced by cholesterol crystals in mouse bone marrow-derived macrophages were established. We also examined the effect of cholesterol on the livers of mice following a 20-week regimen of high-cholesterol diets.

Results

Excess cholesterol interfered with normal cholesterol metabolism both in vitro and in vivo, and led to liver damage and fibrosis in vivo. Further research showed that cholesterol exposure triggered NLRP3 inflammasome activation and programmed cell death called pyroptosis; induced an increase in mitochondrial ROS and a disruption of intracellular redox homeostasis, followed by the opening of the mitochondrial permeability transition pore; and finally induced cellular DNA damage, resulting in the translocation of the double-stranded DNA fragment into the cytoplasm and the activation of the DNA-sensing adaptor STING. The activation of the NLRP3-cGAS-STING axis initiated the downstream cascade reaction and up-regulated the expression of pro-inflammatory cytokines, including IL-1β, TNF-α, and IFN-β, thus facilitating liver damage and fibrosis. Furthermore, honokiol, an active ingredient in Magnolia officinalis, could alleviate liver damage and fibrosis by blocking NLRP3 inflammasome activation, pyroptosis, and the cGAS-STING pathway.

Conclusion

Systematic evidence shows that cholesterol induces liver fibrosis through the activation of the NLRP3-cGAS-STING signaling axis and that honokiol demonstrates interventional efficacy in mitigating this process.