Exogenous hydrogen sulfide mitigates LPS + ATP-induced inflammation by inhibiting NLRP3 inflammasome activation and promoting autophagy in L02 cells

The aim of this study is to investigate whether exogenous hydrogen sulfide (H 2 S) could mitigate lipopolysaccharide (LPS) + Adenosine Triphosphate (ATP)-induced inflammation by inhibiting nucleotide-binding oligomerization domain-like receptor 3 (NLRP3) inflammasome activation and promoting autophagy in L02 cells. We stimulated L02 cells with different concentrations of LPS, then the cell viability, cell apoptosis, and the protein level of NLRP3 inflammasome were detected by MTT and western blot to determine the appropriate LPS concentration used in this study. The cells were divided into 4 group: the cells in control group were cultured with RPMI-1640 for 23.5 h; the cells in LPS + ATP group were cultured with RPMI-1640 for 0.5 h, then were stimulated with 100 ng/ml LPS for 18 h followed by stimulation with 5 mM ATP for 5 h; the cells in Sodium hydrosulfide (NaHS) + LPS + ATP group were pretreated with NaHS for 0.5 h before exposure to LPS for 18 h and ATP for 5 h; the cells in NaHS group were treated with NaHS for 0.5 h, then were cultured with RPMI-1640 for 23 h. Subsequently, the cells in each group were collected, the protein levels of NLRP3, pro-caspase-1, cleaved caspase-1, P62, toll-like receptor 4 (TLR4), nuclear factor-kappa B (NF-κB), LC3, Beclin-1, and interleukin (IL)-1 beta (β) were detected by western blot and enzyme-linked immunosorbent assay. Our results showed that exogenous H 2 S reduced the protein levels of NLRP3, cleaved caspase-1, TLR4, NF-κB, P62, and IL-1β induced by LPS + ATP and increased the ratio of LC3-II/I and the protein levels of Beclin 1 suppressed by LPS + ATP. This study demonstrated that H 2 S might suppress LPS + ATP-induced inflammation by inhibiting NLRP3 inflammasome and promoting autophagy. In conclusion, H 2 S might have potential applications in the treatment of aseptic hepatitis.