LOX-1 gene knockout improves metabolic dysfunction-associated steatohepatitis in mice

Metabolic dysfunction-associated steatohepatitis (MASH), a progressive subtype of metabolic dysfunction-associated steatotic liver disease (MASLD), is characterized by hepatic steatosis, lobular inflammation, and hepatocyte ballooning, and may further progress to liver fibrosis and cirrhosis. Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1), a member of the scavenger receptor family, recognizes and binds oxidized low-density lipoprotein. This study aims to investigate the role of LOX-1 in MASH progression.

LOX-1 expression in MASLD mouse liver was analyzed using Gene Expression Omnibus (GEO) datasets. Immunofluorescence staining was performed to detect LOX-1 and alpha-smooth muscle actin (α-SMA) levels and co-localization in fibrotic liver tissues and LX-2 cells. LOX-1 knockout (Lox-1^-/-) mice were generated using CRISPR/caspase-9 (Cas9) and genotyped by PCR and Sanger sequencing. Wild-type (WT) and Lox-1^-/- mice were randomized into control and Western diet model groups. Serum and liver samples were collected for alanine aminotransferase (ALT) and aspartate aminotransferase (AST) measurement by biochemical kits, liver structure evaluation by hematoxylin and eosin (HE) staining, collagen deposition by Masson staining, lipid accumulation by Oil Red O staining, and fibrotic marker gene expression by real-time quantitative PCR (RT-qPCR). Network pharmacology and search tool for the retrieval of interacting genes/proteins (STRING)-based protein-protein interaction (PPI) with Gene Ontology (GO) enrichment were used to predict downstream targets and pathways.

The results from the GEO datasets GSE30552 and GSE40041 indicated LOX-1 mRNA was upregulated in high fat diet (HFD) and bile duct ligation (BDL) mouse models (both P<0.001). LOX-1 and α-SMA levels were elevated in fibrotic liver tissues. Lox-1^-/- mice were successfully established. Biochemical tests showed that serum AST and ALT levels were significantly elevated in WT mice fed a Western diet (both P<0.001), and these levels decreased after LOX-1 knockout (both P<0.05). HE staining revealed that WT mice on the Western diet exhibited marked hepatocellular ballooning degeneration, steatosis, inflammatory cell infiltration, and periportal fibroplasia, which were significantly ameliorated by LOX-1 knockout. Masson staining demonstrated increased blue-stained collagen fibers in the liver tissues of WT mice fed the Western diet compared with control-diet mice, and LOX-1 knockout inhibited collagen fiber deposition (all P<0.05). RT‑qPCR results showed that hepatic mRNA levels of Acta2, Col1a1, and Timp1 were significantly increased in Western diet-fed mice, and LOX-1 knockout reduced the expression of these fibrogenic marker genes. Oil Red O staining indicated that hepatocytes in WT mice fed the Western diet were notably enlarged, displayed macrovesicular steatosis, and exhibited diffusely distributed red lipid droplets, whereas LOX-1 knockout alleviated hepatic lipid accumulation (both P<0.001). RT‑qPCR results further demonstrated that knockdown of LOX-1 reduced Acta2, Col1a1, and Timp1 mRNA levels in LX‑2 cells (all P<0.05). Immunofluorescence analysis revealed co‑localization of LOX-1 and α‑SMA in LX‑2 cells, and LOX-1 silencing suppressed α‑SMA expression. Network pharmacology suggested LOX-1 may promote MASH via lipid and cholesterol metabolism networks.

LOX-1 gene knockout ameliorates Western diet-induced MASH in mice and may serve as a potential therapeutic target.