[Hydrogen sulfide modulates acute lung injury in sepsis by inhibiting NLRP3 inflammasome activation in mice].

Abstract

Objective: To investigate the effects and mechanisms of the hydrogen sulfide donor GYY4137 on acute lung injury in sepsis. Methods: An acute lung injury model was established using the method of cecal ligation and puncture(CLP). Mice received an intraperitoneal injection of GYY4137 (50 mg/kg) or saline 30 minutes after surgery. C57BL/6J mice were divided into four groups: the sham operation group (Sham), the sham operation with GYY4137 group (GYY4137), the sepsis group (CLP), and the sepsis with GYY4137 group (CLP+GYY4137). Respiratory parameters (minute ventilation volume and expiratory flow 50) were measured using a whole-body plethysmography system. Lung tissue was evaluated by hematoxylin and eosin (H&E) staining, and inflammatory cells were identified by immunofluorescence. mRNA expression of inflammatory factors (interleukin-1β, interleukin-6) and adhesion molecules (vascular endothelial cadherin, intercellular cell adhesion molecule-1, vascular cell adhesion molecule-1) were quantified by real-time quantitative polymerase chain reaction (RT-PCR). Levels of NLRP3, Pro-IL-1β, IL-1β, and the cyclic guanosine monophosphate synthase (cGAS)/stimulator of interferon genes (Sting)/NF-κB signaling proteins were analyzed by Western blotting. In vitro, murine pulmonary microvascular endothelial cells were cultured and exposed to lipopolysaccharide (LPS, 1 μg/ml) and GYY4137 (25 μmol/L) to simulate sepsis-induced damage and to study the mechanism of hydrogen sulfide action. Levels of inflammatory factors and adhesion molecules in cells were quantified by RT-PCR. Data were analyzed for normal distribution using Shapiro-Wilk test, then variance homogeneity by Brown-Forsythe test. P-value<0.05 was set as statistical significance for all analyses. Results: (1) MV and EF50 values were significantly lower in the CLP group [(36.32±3.91)ml/min and (1.43±0.26)ml/s, respectively] compared to the Sham group [(50.14±6.07)ml/min and (2.70±0.46)ml/s, respectively]. These parameters were higher in the CLP+GYY4137 group [(45.83±2.33)ml/min and (2.02±0.16)ml/s, respectively] compared to the CLP group (P<0.05). (2) Severe lung tissue damage, alveolar collapse, increased septal thickening and exudation were observed in the CLP group and significantly reduced in the CLP+GYY4137 group (P<0.05). (3) Infiltration of inflammatory cells and mRNA levels of inflammatory factors and adhesion molecules were increased in the CLP group compared to the Sham group (P<0.05), and decreased in the CLP+GYY4137 group compared to the CLP group (P<0.05). (4) Protein levels of NLRP3, Pro-IL-1β, IL-1β, cGAS, Sting, and NF-κB were higher in the CLP group compared to the Sham group (P<0.05) and were reduced in the CLP+GYY4137 group compared to the CLP group (P<0.05). (5) LPS induced higher levels of inflammatory factors and adhesion molecules in pulmonary endothelial cells compared to the control, which were reduced in cells co-treated with GYY4137 and LPS (P<0.05). Conclusion: The hydrogen sulfide donor GYY4137 effectively modulates acute lung injury in septic mice by inhibiting NLRP3 inflammasome activation via the cGAS/Sting/NF-κB signaling pathway.