IDDF2024-ABS-0295 FoxO1 deficiency links nonalcoholic steatohepatitis with cysteine metabolism in hepatocytes

Background The high morbidity and poor prognosis of non-alcoholic steatohepatitis (NASH) have been regarded as a serious global burden. Hepatocytes are important in maintaining liver homeostasis and modulating inflammatory responses. There is evidence that the transcriptional factor Forkhead box O1 (FoxO1) is correlated with lipid and glucose metabolism. However, the mechanism underlying the role of hepatocyte FoxO1 in inflammation remains unclear. Methods NASH animal model was constructed using a methionine/choline-deficient diet (MCD) in wild-type (WT) and hepatocyte-specific FoxO1 knockout (FoxO1-KO) mice. At the end of the experiment, ALT, AST and liver pathological changes were compared between WT and FoxO1-KO mice to determine the effects of hepatocyte FoxO1 on NASH phenotype. Meanwhile, the hepatic inflammatory cell model was established by Lipopolysaccharide (LPS)-induced manner in WT and FoxO1-KO cells. The cellular transcriptome profiles were performed to identify the biological pathways and genes targeted by FoxO1. Results In both the control diet group (MCS) and NASH modeling group (MCD), depletion of hepatocyte FoxO1 significantly aggravated liver steatosis, inflammation, and fibrosis (IDDF2024-ABS-0295 Figure 1. Depletion of hepatocyte FoxO1 aggravated NASH phenotype in vivo (A,B)). The serum levels of ALT and AST were also enhanced in FoxO1-KO mice (IDDF2024-ABS-0295 Figure 1. Depletion of hepatocyte FoxO1 aggravated NASH phenotype in vivo (C,D)), which suggested that depletion of hepatocyte FoxO1 exacerbated NASH progression. Consistent with the in vivo data, Depletion of FoxO1 in HepG2 cells enhanced inflammatory cytokine expression (IDDF2024-ABS-0295 Figure 2. Effects of hepatocyte FoxO1 on LPS-induced inflammation in vitro (A,B)). Next-generation sequencing (NGS) analysis revealed that cysteine and methionine metabolism-associated genes were dramatically down-regulated in FoxO1-KO cells (IDDF2024-ABS-0295 Figure 2. Effects of hepatocyte FoxO1 on LPS-induced inflammation in vitro (C,D)). Furthermore, FoxO1 depletion significantly inhibited the mRNA and protein level of cystathionine γ-lyase (CTH), a core gene of cysteine metabolism (IDDF2024-ABS-0295 Figure 2. Effects of hepatocyte FoxO1 on LPS-induced inflammation in vitro (E,F)). Conclusions This study demonstrated that the depletion of hepatocyte FoxO1 significantly aggravated NASH progression in vivo and in vitro. Considering that CTH was reported to exhibit anti-inflammatory effects in keratinocytes and kidney tissue, we hypothesized that hepatocyte FoxO1 inhibits inflammatory responses by targeting CTH, which could provide a potential therapeutic approach for NASH treatment.