Hydrogen gas (H) pretreatment improves lipopolysaccharide-induced acute liver injury in mice by inhibiting NLRP3 inflammasome activation and pyroptosis signaling.

Abstract

BACKGROUND: The liver is extremely vulnerable to endotoxin-induced damage during sepsis. Hydrogen gas (H) is a colorless and odorless gas molecule with anti-oxidative and anti-inflammatory actions. However, the effects of Hintraperitoneal injection on sepsis-induced acute liver injury and the possible mechanisms remain unclear. METHODS: Biochemical analysis, H&E staining, immunoblotting, immunofluorescence, and TUNEL staining were used to investigate the effects and mechanisms of Hintraperitoneal injection on lipopolysaccharide (LPS)-induced acute liver injury in mice. AML12 cells and pharmacological rescue experiment were used to confirmed the target of H. RESULTS: Hpretreatment by intraperitoneal injection improved LPS-induced acute liver injury in mice as indicated by reducing inflammatory cells infiltration in the liver, down-regulating serum ALT and AST levels, decreasing hepatic 3-nitrotyrosine, MDA, and MPO levels, and up-regulating hepatic GSH levels. Mechanistically, Hsuppressed TLR4 to IKK-NF-κB and to MAPK (ERK, p38 and JNK) signaling, and thus reducing pro-inflammatory cytokines, including TNF-α, IL-1β, and IL-18 levels in the liver of LPS-challenged mice. Moreover, the hepatic pyroptosis signaling including NLRP3 inflammasome (NLRP3, ASC, and Caspase-1) to GSDMD, Caspase-8/11 to GSDMD, Caspase-3 to GSDME, and TUNEL staining in LPS-challenged mice were all reversed by Htreatment. The pharmacological rescue experiments by agonist (nigericin) and antagonist (MCC950) of NLRP3 further confirm the action of Hon NLRP3. CONCLUSIONS: Hpretreatment by intraperitoneal injection alleviated LPS-induced acute liver injury in mice by modulating redox homeostasis, TLR4-mediated innate immune signaling, NLRP3 inflammasome activation and pyroptosis signaling.