LPS-Induced Acute Lung Injury Model

LPS-induced ALI was performed to establish an ALI mouse model. Briefly, 1 mg/mL of LPS (Escherichia coli, serotype 055:B5; Sigma-Aldrich, St. Louis, MO, USA) was injected into mice through intratracheal instillation, and the control group was injected with the same volume of sterile phosphate-buffered saline (PBS), as in Wang et al. [27 (link)]. Mice were then sacrificed under ether narcotization at 24 h after challenge with LPS or PBS to collect 1% heparin-anticoagulated peripheral whole blood, spleen, bronchoalveolar lavage fluid (BALF), and lung tissues. The WT+LPS+PGRN and PGRN^−/−+LPS+PGRN groups were treated with 2 μg of recombinant-mouse PGRN protein (CF, R&D Systems, Minneapolis, MN, USA) 30 min after LPS challenge through intratracheal instillation [19 (link)]. Blood, spleen, BALF, and lung tissues were collected as indicated for further analysis.