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Updated: Sep 19, 2025
Inducing Acute Lung Injury in Mice by Direct Intratracheal Lipopolysaccharide Instillation
Published on: July 6, 2019
The Fli1 transcription factor aggravates lipopolysaccharide-induced human pulmonary microvascular endothelial cell
Zhou Zheng1, Lei Liu1, Hao Zhang1
1Department of Emergency Medicine, Tongren Hospital Affiliated to Wuhan University, Wuhan Third Hospital, Wuhan, China.
Objective:
Pulmonary microvascular endothelial cell (PMEC) injury is a hallmark of septic acute lung injury (ALI). Elevation of chemokine C-X-C motif ligand 2 (CXCL2) is associated with inflammatory response in various diseases. Recent studies have demonstrated the involvement of CXCL2 in septic ALI. Herein, the role and mechanism of CXCL2 in regulating PMEC inflammation and apoptosis in septic ALI were explored.
Materials And Methods:
Human PMECs (HPMECs) were treated with lipopolysaccharide (LPS) for the establishment of in vitro septic ALI models. HPMEC viability was validated using CCK-8 assay. HPMEC apoptosis was evaluated by flow cytometry analysis. Measurement of proinflammatory cytokine concentration was conducted using enzyme-linked immunosorbent assay kits. RT-qPCR were required for determining gene levels. Western blotting was prepared for testing friend leukemia integration 1 (Fli1) and CXCL2 protein levels. The binding of Fli-1 to CXCL2 promoter was confirmed by chromatin immunoprecipitation and luciferase reporter assays.
Results:
LPS upregulated CXCL2 expression in HPMECs. Moreover, LPS administration suppressed HPMEC viability and accelerated HPMEC inflammation and apoptosis, which was antagonized by CXCL2 depletion. Mechanistically, Fli1 served as a transcription factor and bound to CXCL2 promoter. In rescue assays, CXCL2 overexpression counteracted the restrictive impact of Fli1 deficiency on LPS-induced HPMEC apoptotic behaviors and inflammatory response.
Conclusions:
The Fli1 transcription factor aggravates LPS-induced HPMEC dysfunction via binding to CXCL2 promoter in septic ALI.
Insights
The transcription factor Fli1 worsens lung cell injury in sepsis by activating CXCL2. Reducing CXCL2 levels protected lung cells from sepsis-induced damage and inflammation.
Area of Science:
- Pulmonary and Inflammation Research
- Molecular Biology
- Cellular Biology
Background:
- Pulmonary microvascular endothelial cell (PMEC) injury is a key feature of septic acute lung injury (ALI).
- Chemokine C-X-C motif ligand 2 (CXCL2) elevation is linked to inflammation and implicated in septic ALI.
- Understanding the precise role of CXCL2 in septic ALI is crucial for developing targeted therapies.
Purpose of the Study:
- To investigate the role and underlying mechanism of CXCL2 in regulating PMEC inflammation and apoptosis during septic ALI.
- To explore the interaction between Fli1 and CXCL2 in the context of LPS-induced PMEC injury.
Main Methods:
- Established *in vitro* septic ALI models using human PMECs (HPMECs) treated with lipopolysaccharide (LPS).
- Assessed HPMEC viability (CCK-8), apoptosis (flow cytometry), and proinflammatory cytokine levels (ELISA).
- Quantified gene and protein expression (RT-qPCR, Western blotting) and confirmed transcription factor binding (ChIP, luciferase assays).
Main Results:
- LPS treatment upregulated CXCL2 expression in HPMECs, suppressed viability, and increased inflammation and apoptosis.
- Depletion of CXCL2 counteracted the detrimental effects of LPS on HPMECs.
- Fli1 was identified as a transcription factor that binds to the CXCL2 promoter, mediating LPS-induced PMEC dysfunction.
Conclusions:
- Fli1 exacerbates LPS-induced HPMEC dysfunction in septic ALI by binding to the CXCL2 promoter.
- CXCL2 plays a significant role in PMEC inflammation and apoptosis in septic ALI.
- Targeting the Fli1-CXCL2 pathway may offer a therapeutic strategy for septic ALI.
