RESUMO
BACKGROUND AND AIMS: Gut microbiota play a prominent role in the pathogenesis of metabolic dysfunction-associated steatotic liver disease (MASLD). Interleukin-33 (IL-33) is highly expressed at mucosal barrier sites and regulates intestinal homeostasis. Herein, we aimed to investigate the role and mechanism of intestinal IL-33 in MASLD. APPROACH AND RESULTS: In both human and mice with MASLD, hepatic expression of IL-33 and its receptor suppression of tumorigenicity 2 (ST2) showed no significant change compared to controls, while serum soluble ST2 levels in humans, as well as intestinal IL-33 and ST2 expression in mice were significantly increased in MASLD. Deletion of global or intestinal IL-33 in mice alleviated metabolic disorders, inflammation and fibrosis associated with MASLD by reducing intestinal barrier permeability and rectifying gut microbiota dysbiosis. Transplantation of gut microbiota from IL-33 deficiency mice prevented MASLD progression in wild type (WT) mice. Moreover, IL-33 deficiency resulted in a decrease in the abundance of trimethylamine N-oxide (TMAO)-producing bacteria. Inhibition of TMAO synthesis by 3,3-dimethyl-1-butanol (DMB) mitigated hepatic oxidative stress in mice with MASLD. Nuclear IL-33 bound to hypoxia inducible factor-1α (HIF-1α) and suppressed its activation, directly damaging the integrity of intestinal barrier. Extracellular IL-33 destroyed the balance of intestinal Th1/Th17 and facilitated Th1 differentiation through the ST2-Hif1a-Tbx21 axis. Knockout of ST2 resulted in a diminished MASLD phenotype resembling that observed in IL-33 deficiency mice. CONCLUSIONS: Intestinal IL-33 enhanced gut microbiota-derived TMAO synthesis and aggravated MASLD progression through dual regulation on HIF-1α. Targeting IL-33 and its associated microbiota may provide a potential therapeutic strategy for managing MASLD.
RESUMO
BACKGROUND & AIMS: Fulminant viral hepatitis (FVH) is a life-threatening disease, but its pathogenesis is not fully understood. Neutrophil extracellular traps (NETs) were an unrecognized link between inflammation and coagulation, which are 2 main features of FVH. Here, we investigated the role and mechanism of NETs in the pathogenesis of FVH. METHODS: A mouse model of FVH was established by murine hepatitis virus strain-3 infection. Liver leukocytes of infected or uninfected mice were used for single-cell RNA sequencing and whole-transcriptome sequencing. NETs depletion was achieved using DNase 1. Acetaminophen was used to establish a mouse model of non-virus-caused acute liver failure. Clinically, NETs-related markers in liver, plasma, and peripheral neutrophils were assessed in patients with hepatitis B virus (HBV)-related acute liver injury. RESULTS: Increased hepatic NETs formation was observed in murine hepatitis virus strain-3-infected mice, but not in acetaminophen-treated mice. NETs depletion improved the liver damage and survival rate in FVH by inhibiting hepatic fibrin deposition and inflammation. An adoptive transfer experiment showed that neutrophil-specific fibrinogen-like protein 2 (FGL2) promoted NETs formation. FGL2 was found to directly interact with mucolipin 3, which regulated calcium influx and initiated autophagy, leading to NETs formation. Clinically, increased plasma NETs level was associated with coagulation dysfunction in patients with HBV acute liver injury. Colocalization of FGL2, NETs, and fibrin in liver was observed in these patients. CONCLUSIONS: NETs aggravated liver injury in FVH by promoting fibrin deposition and inflammation. NETs formation was regulated by the FGL2-mucolipin 3-autophagy axis. Targeting NETs may provide a new strategy for the treatment of FVH.
