Abstract
BACKGROUND AND AIMS: Alcohol-associated liver disease (ALD) is a leading cause of liver-related morbidity and mortality worldwide, with no currently effective treatment. ALD is caused by excessive lipid buildup, which eventually triggers inflammation and fibrosis in the liver. Activation of hepatic Kupffer cells (KCs) and macrophages drives liver inflammation, which can worsen alcohol-induced liver injury. The autophagy-lysosome system is crucial for macrophages to support their innate immune functions. Transcription factor EB (TFEB) is a key regulator of autophagy and lysosomal biogenesis, but the role of macrophage TFEB in ALD development is unknown. The aim of this study was to evaluate the effects of Gao-binge alcohol consumption on myeloid cell TFEB and elucidate the role of myeloid TFEB in ALD. METHODS: Two-to-three-month-old male and female LysM Cre(-) (WT) and LysM Cre(+) Tfeb (Flox/Flox (f/f)) (myeloid-Tfeb KO) mice were subjected to chronic alcohol feeding plus an acute binge following the Gao-binge model. Serum alanine aminotransferase, aspartate aminotransferase, triglycerides, and cholesterol content were determined using biochemical assays. Total hepatic protein content and messenger RNA (mRNA) levels of autophagy-related proteins and inflammatory markers were determined using immunoblotting, immunohistochemistry, and real-time quantitative polymerase chain reaction (RT-qPCR). Isolated hepatic infiltrating macrophages and KCs from mice given intragastric ethanol infusions were analyzed by Western blot for TFEB and autophagy-related protein content. Raw 264.7 macrophages were treated with ethanol, lipopolysaccharide (LPS), and LPS plus ethanol to examine nuclear TFEB translocation using immunofluorescence. RESULTS: We found that TFEB levels were higher in macrophage/KC cells than in hepatocytes and cholangiocytes. While ethanol feeding increased serum alanine aminotransferase and aspartate aminotransferase levels, as well as hepatic triglyceride levels, no significant differences were observed between WT and myeloid-Tfeb KO mice. The number of F4/80-positive KCs/macrophages was similar in all four experimental groups, but hepatic neutrophil infiltration increased in alcohol-fed myeloid-Tfeb KO mice. LPS or ethanol alone induced nuclear TFEB translocation only moderately in Raw 264.7 macrophages. CONCLUSIONS: Our findings suggest that myeloid TFEB is dispensable for alcohol-induced liver injury in mice.