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

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.