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Updated: Nov 12, 2025
Inducing Acute Lung Injury in Mice by Direct Intratracheal Lipopolysaccharide Instillation
Published on: July 6, 2019
[6-Formylindolo[3,2-b]carbazole alleviates lipopolysaccharide-induced acute lung injury via suppressing endoplasmic
Lujing Shao1,2, Xiaomeng Tang1,2, Yun Cui2
1Department of Critical Care Medicine, Shanghai Children's Hospital, Shanghai Jiao Tong University, Shanghai 200040, China.
Objective:
To investigate the effect and mechanism of 6-formylindolo[3,2-b]carbazole (FICZ) on lipopolysaccharide (LPS)-induced acute lung injury (ALI) in mice.
Methods:
Male C57BL/6J mice aged 8-12 weeks were divided into 4 groups with 8 mice in each group, according to the method of simple random sampling. Sepsis-induced ALI mice model was established by intraperitoneal injection of LPS 5 mg/kg (LPS group), and phosphate buffer saline (PBS) control group (PBS group) was injected with equal volume of PBS. The LPS+FICZ group was intervened by intraperitoneal injection of 1 μg FICZ 1 hour after LPS stimuli, while the FICZ control group (FICZ group) was given the same amount of FICZ 1 hour after intraperitoneal injection of PBS. Serum and lung tissue were collected 24 hours after LPS stimuli, and the pathological changes of lung tissue were analyzed by hematoxylin-eosin (HE) staining and wet/dry weight (W/D) ratio of lung tissue. The concentrations of inflammatory factors in serum and lung tissue were detected by enzyme linked immunosorbent assay (ELISA). The expression levels of endoplasmic reticulum stress signaling pathway related molecules were detected by real-time fluorescent quantitative polymerase chain reaction (RT-qPCR) and Western blotting.
Results:
Compared with PBS group, inflammatory cell infiltration, alveolar collapse and obvious alveolar exudative lesions had increased, lung tissue W/D ratio was significantly increased, serum interleukin-6 (IL-6) level, lung tissue IL-6 mRNA expression, and the mRNA expressions of glucose-regulated protein 78 (GRP78), protein kinase R-like endoplasmic reticulum kinase (PERK), CCAAT/EBP homologous protein (CHOP), and the protein expressions of GRP78, PERK, activating transcription factor 6 (ATF6), CHOP in lung tissue were significantly increased in LPS group. However, the indexes of FICZ group were not affected. Compared with LPS group, LPS+FICZ group had less inflammatory cell infiltration, relatively intact alveolar structure. Lung W/D weight ratio in LPS+FICZ group was significantly decreased (5.38±0.10 vs. 6.60±0.30, P < 0.01), so as serum IL-6 (ng/L: 15.55±3.77 vs. 32.22±3.84) and lung IL-6 mRNA expression (2-ΔΔCt: 0.79±0.21 vs. 6.89±0.92, both P < 0.01). The mRNA expressions of GRP78, PERK and CHOP were also significantly decreased [GRP78 mRNA (2-ΔΔCt): 1.90±0.16 vs. 7.55±1.29, PERK mRNA (2-ΔΔCt): 1.68±0.20 vs. 4.54±0.89, CHOP mRNA (2-ΔΔCt): 1.13±0.24 vs. 4.44±1.13, all P < 0.05], and the protein expressions of GRP78, PERK, ATF6 and CHOP were significantly decreased (GRP78/GAPDH: 0.59±0.02 vs. 0.77±0.01, PERK/GAPDH: 0.48±0.03 vs. 1.04±0.05, ATF6/GAPDH: 0.51±0.03 vs. 0.65±0.01, CHOP/GAPDH: 0.91±0.05 vs. 1.11±0.07, all P < 0.05).
Conclusions:
FICZ protects LPS-induced ALI possibly via suppressing endoplasmic reticulum stress and reducing IL-6 expression in blood and lung tissue.
Insights
6-formylindolo[3,2-b]carbazole (FICZ) treatment mitigated lipopolysaccharide (LPS)-induced acute lung injury (ALI) in mice. FICZ reduced inflammation and endoplasmic reticulum stress, offering a potential therapeutic strategy for ALI.
Area of Science:
- Biomedical research
- Molecular biology
- Pathology
Background:
- Acute lung injury (ALI) is a severe condition with high mortality.
- Lipopolysaccharide (LPS) is a potent inducer of ALI, triggering inflammatory responses and cellular damage.
- Endoplasmic reticulum (ER) stress is implicated in the pathogenesis of LPS-induced ALI.
Purpose of the Study:
- To investigate the protective effects of 6-formylindolo[3,2-b]carbazole (FICZ) against LPS-induced ALI in a mouse model.
- To elucidate the underlying mechanisms, focusing on ER stress and inflammatory cytokine expression.
Main Methods:
- Establishment of a sepsis-induced ALI mouse model using LPS.
- Intervention with FICZ in LPS-treated mice.
- Assessment of lung pathology via HE staining and W/D ratio.
- Quantification of inflammatory factors (IL-6) and ER stress markers (GRP78, PERK, CHOP, ATF6) using ELISA, RT-qPCR, and Western blotting.
Main Results:
- LPS challenge significantly increased lung injury, inflammation (IL-6), and ER stress markers (GRP78, PERK, CHOP, ATF6).
- FICZ treatment markedly reduced inflammatory cell infiltration, alveolar damage, and lung W/D ratio.
- FICZ administration significantly decreased serum and lung IL-6 levels, as well as the expression of ER stress-related molecules at both mRNA and protein levels.
Conclusions:
- FICZ demonstrates significant protective effects against LPS-induced ALI in mice.
- The mechanism involves the suppression of endoplasmic reticulum stress and reduction of IL-6 expression.
- FICZ represents a promising therapeutic candidate for managing ALI.
