S100A9/RAGE pathway regulation of mitophagy and the effect of JianPi LiShi YangGan formula in acute-on-chronic liver failure.

ETHNOPHARMACOLOGICAL RELEVANCE: Mitophagy regulates cellular homeostasis and liver inflammation; however, it is inhibited in acute-on-chronic liver failure (ACLF), which drives disease progression. The JianPi LiShi YangGan formula (YGF) has the potential to improve inflammatory responses and reduce mortality in patients with ACLF. However, the precise mechanisms underlying these effects remain unknown.

AIM OF THE STUDY: We investigated the role of S100A9/RAGE signaling in mitophagy and the protective effects of traditional Chinese medicinal compounds on ACLF.

MATERIALS AND

METHODS

An ACLF mouse model was established using carbon tetrachloride, lipopolysaccharide, and d-galactose. Hematoxylin and eosin staining and enzyme-linked immunosorbent assay were employed to evaluate the hepatoprotective effect of YGF in ACLF mice. Mitochondrial damage was assessed using transmission electron microscopy. Protein levels of mitophagy-related indicators were assessed through immunohistochemistry and western blotting, and immunofluorescence staining was performed to observe Lamp2 and COX-IV co-localization.

RESULTS

The hepatocytes of ACLF mice contained damaged mitochondria, decreased mitophagy-related protein (Pink1, Parkin, and LC3B) expression and activated S100A9/RAGE signaling. Inhibiting S100A9 or RAGE improved liver injury in ACLF mice and enhanced Lamp2-COX-IV co-localization. In alpha mouse liver 12 (AML12) cells overexpressing RAGE, recombinant S100A9 protein inhibited mitophagy induced by 3-chlorocarbonyl benzoyl chloride. YGF reduced mitochondrial damage, increased Pink1, Parkin, and LC3B levels, and enhanced mitophagy while inhibiting S100A9/RAGE activation in the hepatocytes of ACLF mice.

CONCLUSIONS

This study found that S100A9/RAGE pathway activation impairs mitophagy, and YGF alleviates liver injury by downregulating S100A9 and RAGE signaling, which may be a novel therapeutic strategy for ACLF.