Inflammation and fibrosis in mouse lung tissue after LPS challenge. (A) The pathological changes in mouse lung tissue 72 hours and 28 days after intraperitoneal injection of LPS were observed by means of HE staining (HE, A, magnification ×200). Pulmonary fibrosis was observed by means of Van-Gieson staining (VG, magnification ×200). (B) The Ashcroft fibrosis score was used to compare the degrees of the pulmonary fibrosis 28 days after application of LPS in mice. The mice showed obvious inflammatory reactions in lung tissue 72 hours after LPS challenge. Typical pulmonary interstitial fibrosis appeared 4 weeks later. Infection with TLR4-shRNA lentivirus significantly inhibited the inflammatory reaction and fibrosis induced by LPS. BC: blank control group; NC: negative control group; PC: positive control group; TI: TLR4 inhibition group; TI+L: TLR4 inhibition group stimulated with LPS; 3d: specimens were collected 72 hours after LPS (or physiological saline) challenge. 4w: specimens were collected 28 days after LPS (or physiological saline) challenge. Each subgroup contains 6 specimens respectively (n = 6). Results were expressed as mean ± standard deviation indicated with column graph and error bar. Statistical significance was defined at p values < 0.05. *: P < 0.05 versus PC.