Sesquiterpenoids of Dendrobium nobile Lindl. aqueous extract for inhibition alcoholic liver injury through RTK/ELF4regulated inflammation in mouse hepatic macrophages

Dendrobium nobile Lindl. (D.nobile) contributes to an hepatoprotective effect. Unfortunately, the active components and molecular mechanism of D.nobile in alcoholic liver injury is still elusive. Here, we investigated the function of main active ingredients in D.nobile aqueous extract (DNAE) in vivo on regulating the expression of E74-like factor 4 (ELF4) in liver macrophages to against alcoholic liver injury through reducing inflammatory response. The differential expressed genes (DEGs) and transcription factors (TFs) in mouse liver immune cells were determined by single-cell transcriptome analysis, and ELF4 expression in macrophages was determined by RT-PCR and Western blot. The main metabolites of DNAE in vivo were determined by LC-MS/MS analysis. The molecular docking was used to analyze the interactions between metabolites of DNAE and ELF4 signaling. The results showed that DNAE administration showed a reduction of oxidative damage and inflammatory response when mice were treatment with a daily alcoholic intragastric for 14 days. What is more, alcohol primarily affected the expression of macrophages genes among liver immune cells and the DEGs were mainly regulated by transcription factor ELF4, which was relevant to inflammation reaction in macrophages. Meanwhile, DNAE upregulated ELF4 expression through the RTK/ERK1/2 axis. ELF4 inhibits macrophage inflammatory responses via transactivating its upstream target genes S100A9. Furthermore, the main metabolites of DNAE were sesquiterpenoids and alkaloids in vivo, and sesquiterpenoids are more strongly correlated with the cell membrane cascade response RTK/ERK1/2 signaling pathway, which could regulate the expression of ELF4. This study explores the essentiality of sesquiterpenoids to regulate ELF4 in macrophages and indicates that sesquiterpenoids could be as an anti-inflammation drug or a daily functional healthcare product to alcoholic liver disease.