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Updated: Mar 28, 2026
Inducing Acute Lung Injury in Mice by Direct Intratracheal Lipopolysaccharide Instillation
Published on: July 6, 2019
[Effects of microRNA-155 on mice with lipopolysaccharide-induced acute lung injury]
Wenting Li1, Bin Shu, Zhen Liu
1Graduate School of Hebei North University, Zhangjiakou Hebei 075400, China.
Objective:
To study the effects of microRNA (miR)-155 on mice with acute lung injury induced by lipopolysaccharide (LPS).
Methods:
According to the random number table, 30 C57 mice were divided into group LPS, group miR-155 inhibitor, group miR control, group miR-155 mimics, normal control group, with 6 mice in each group. Mice in group LPS and the other three treatment groups were given 5 µl LPS (20 µg/µl, in the dose of 4 mg/kg) to reproduce acute lung injury model. Half an hour after injury, group LPS, group miR-155 inhibitor, group miR control, group miR-155 mimics were injected with saline, miR-155 inhibitor, miR control and miR-155 mimics through trachea. Mice in normal control group were received no treatment. All mice were anesthetized after 24 h, while lung tissue samples were harvested for histomorphological observation, detection of mRNA expressions of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) with SYBR Green real-time polymerase chain reaction (PCR), detection of miR-155 in group miR-155 inhibitor, group miR control, group miR-155 mimics by Taqman PCR. The protein expression of cyclooxygenase-2 (COX-2) was determined by western blot. Data were statistically analyzed.
Results:
The relative mRNA expression values of TNF-α were 24.49 ± 3.64, 38.92 ± 3.40, 36.00 ± 3.86, 12.56 ± 2.06, 1.04 ± 0.41 in group LPS, group miR-155 inhibitor, group miR control, group miR-155 mimics, normal control group. The relative mRNA expression values of IL-1β were 55.96 ± 4.87, 62.90 ± 6.41, 59.99 ± 6.48, 25.33 ± 3.50, 1.11 ± 0.44 in group LPS, group miR-155 inhibitor, group miR control, group miR-155 mimics, normal control group. The differences of TNF-α and IL-1β in group miR-155 mimics were statistically significant by compared with group LPS, group miR-155 inhibitor, group miR control (P < 0.05). The differences were not statistically significant among group LPS, group miR-155 inhibitor, group miR control. Western blot analysis showed the relative expression values of COX-2 were 0.94 ± 0.06, 0.96 ± 0.09, 0.91 ± 0.03, 0.79 ± 0.04, 0.63 ± 0.07 in group LPS, group miR-155 inhibitor, group miR control, miR-155 mimics and normal control group. The value in normal control group was significantly lower than other groups (P < 0.05).
Conclusion:
Using the miR-155 can effectively alleviate the lung inflammation in mice with acute lung injury induced by LPS.
Insights
MicroRNA-155 (miR-155) effectively alleviates acute lung injury in mice induced by lipopolysaccharide (LPS). Administration of miR-155 mimics reduced key inflammatory markers, suggesting a therapeutic potential for lung inflammation.
Area of Science:
- Molecular Biology
- Immunology
- Respiratory Medicine
Background:
- Acute lung injury (ALI) induced by lipopolysaccharide (LPS) is a significant clinical challenge.
- MicroRNAs (miRNAs) play crucial roles in regulating inflammatory responses.
- The specific role of miR-155 in LPS-induced ALI requires further elucidation.
Purpose of the Study:
- To investigate the therapeutic effects of microRNA-155 (miR-155) on lipopolysaccharide (LPS)-induced acute lung injury (ALI) in a mouse model.
- To assess the impact of miR-155 modulation on inflammatory cytokine and protein expression in ALI.
Main Methods:
- A mouse model of LPS-induced ALI was established.
- Mice were treated with miR-155 inhibitor, miR-155 mimics, or control substances.
- Lung tissues were analyzed for histomorphology, mRNA expression of TNF-α and IL-1β via real-time PCR, and COX-2 protein expression via Western blot.
Main Results:
- miR-155 mimics significantly reduced the mRNA expression of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) compared to the LPS group (P < 0.05).
- The expression of cyclooxygenase-2 (COX-2) protein was also downregulated in the miR-155 mimics group.
- No significant differences in TNF-α and IL-1β levels were observed among the LPS, miR-155 inhibitor, and miR control groups.
Conclusions:
- Modulation of miR-155, particularly using miR-155 mimics, demonstrates a protective effect against LPS-induced acute lung injury in mice.
- miR-155 effectively alleviates lung inflammation by downregulating key pro-inflammatory mediators like TNF-α, IL-1β, and COX-2.
- These findings suggest that miR-155 holds therapeutic potential for managing inflammatory lung conditions such as ALI.
