ABSTRACT
Objective: To investigate the potential function of GSDMD in lipopolysaccharide (LPS) induced acute lung injury (ALI) during the inflammatory reaction and lung tissue damage. Methods: Twenty wild-type C57BL/6 mice and twenty GSDMD knockout C57BL/6 mice were randomized into the WT-sham group, WT-ALI group, Knockout (KO)-sham group and KOALI group. The ALI was induced by intratracheal injection of LPS (1 mg/kg), using PBS as the treatment control. To examine the inflammatory reaction and tissue damage in the lung, the lung tissue and bronchoalveolar lavage fluid (BALF) were collected. HE staining of lung tissue and the semi-quantitative score of lung injury were performed. The wet/dry ratio of lung tissue and the total protein concentration in BALF were measured by BCA. The levels of TNF-a, IL-1β, and IL-6 in BALF were detected by ELISA. The expression of pyroptosis-related proteins in BALF and lung tissues were detected by Western blotting. Results: Compared with the WT-ALI group, the lung injury pathological score, wet/dry ratio, and total protein concentration were all significantly lower in KO-ALI group (P<0.01). Furthermore, the total protein level, TNF-a, IL-1β, and IL-6 levels in BALF were significantly lower in KO-ALI group (P<0.05 or P<0.01). There was no GSDMD and GSDMD-NT expression in the KO mice. After LPS stimulation, the expression levels of caspase-1 and caspase-11 were up-regulated in both wild-type and knockout mice (P<0.01). Conclusions: The expression and activation of GSDMD protein in the lung tissue of mice could be induced by intratracheal instillation of LPS and knockout of GSDMD can inhibit the inflammation level of the lung tissue and reduce its damage degree in mice.