Honokiol ameliorates hepatic fibrosis by inducing lysosomal membrane permeabilization and impairing lipophagy in hepatic stellate cells

Lipophagy in HSCs (hepatic stellate cells) is associated with loss of stellate cell retinol storage and increased β oxidation rate, indicating that the increase in lipophagy serves to provide energy for HSC activation, and contributes to hepatic fibrosis. Honokiol (HNK), a bioactive lignan extracted from Houpoea officinalis, shows effective anti fibrotic and anti inflammatory activities in multiple hepatic diseases. In our study, HNK inhibited activation and induced lipid droplet accumulation in HSC-LX2 cells, without affecting hepatocyte lipid droplets. Fluorescence imaging of EGFP-mCherry-LC3B and lipid staining revealed that HNK suppressed the autophagic degradation of lipid droplets. Notably, Galectin-3 overexpression restored lysosomal function, reduced autophagosome and lipid droplet accumulation, and reversed HNK's effects. Mechanistically, HNK activates Cathepsin B (CTSB) mediated lysosomal associated membrane protein 1 (LAMP1) degradation, thereby promoting lysosomal membrane permeabilization (LMP), impairing lipophagy, and promoting HSC-LX2 inactivation. Besides, TFEB activator 1 attenuated the effects of HNK by reversing HNK induced LAMP1 degradation and restoring lysosomal function. In vivo, HNK ameliorated CCl₄ induced hepatic fibrosis, reduced Collagen deposition, and decreased expression of HSC activation markers. In conclusion, HNK induces LMP and impairs lipophagy by activating CTSB mediated LAMP1 degradation, thereby inhibiting HSC activation and ultimately reversing hepatic fibrosis. Our research has further elucidated the mechanisms by which HNK exhibits anti liver fibrotic effects, thereby providing therapeutic strategies and potential candidates for hepatic fibrosis treatment.

Hepatic fibrosis; Hepatic stellate cells; Honokiol; Lipophagy; Lysosomal membrane permeabilization.