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Bronchoalveolar Lavage Exosomes in Lipopolysaccharide-induced Septic Lung Injury
Published on: May 21, 2018
MicroRNA-16 regulates lipopolysaccharide-induced inflammatory factor expression by targeting TLR4 in normal human
Xiaobo Li1, Qian Chu1, Huaqi Wang1
1Department of Respiratory and Critical Care Medicine, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan 450052, P.R. China.
Abstract:
Acute lung injury (ALI) is mainly caused by inflammation and is associated with high mortality rates. Emerging evidence has suggested that microRNAs (miRNAs or miRs) serve a significant function in ALI. However, the fundamental mechanism underlying ALI remain to be fully elucidated. Although miR-16 has been reported to be involved in the occurrence and development of a number of diseases its association with ALI has not been previously investigated. Therefore, the present study aimed to explore the role of miR-16 in the lipopolysaccharide (LPS)-induced ALI model. The expression levels of tumor necrosis factor α (TNF-α), interleukin (IL)-1β and IL-6 were measured by ELISA in the blood samples of rats with ALI and in the normal human bronchial epithelial (NHBE) cell line. The role of miR-16 in inflammation was evaluated using gene overexpression and silencing experiments in NHBE cells by reverse transcription-quantitative PCR. In addition, the expression levels of inflammatory factors TNF-α, IL-1β and IL-6 were also determined using ELISA. The potential interaction between miR-16 and TLR4 was assessed using bioinformatics analysis by the TargetScan database and then verified in 293T cells using luciferase reporter assay. The expression of miR-16 was notably decreased in the lung tissues of rats with LPS-induced ALI compared with the PBS treated-group. Additionally, the levels of the proinflammatory cytokines TNF-α, IL-1β and IL-6 were reduced following transfection of NHBE cells with miR-16 mimics compared with those in the miR-negative control group. Western blot analysis revealed that miR-16 overexpression could downregulate TLR4 expression in NHBE cells compared with that in the miR-NC group. Luciferase reporter assay confirmed that TLR4 may be directly targeted by miR-16. The effect of miR-16 on TLR4 was rescued in NHBE cells following treatment with LPS. Overall, these aforementioned findings suggest that miR-16 may serve a protective role against LPS-mediated inflammatory responses in NHBE cells by regulating TLR4, where this mechanism may be considered to be a novel approach for treating ALI in the future.
Insights
MicroRNA-16 (miR-16) shows protective effects against acute lung injury (ALI) by reducing inflammation. This study reveals miR-16 regulates Toll-like receptor 4 (TLR4), offering a potential new treatment strategy for ALI.
Area of Science:
- Molecular Biology
- Immunology
- Respiratory Medicine
Background:
- Acute lung injury (ALI) is a severe inflammatory condition with high mortality.
- MicroRNAs (miRNAs) are increasingly recognized for their role in ALI pathogenesis.
- The specific role of miR-16 in ALI remains largely unexplored.
Purpose of the Study:
- To investigate the function of miR-16 in a lipopolysaccharide (LPS)-induced ALI model.
- To elucidate the underlying molecular mechanisms involving miR-16 in ALI.
- To explore miR-16 as a potential therapeutic target for ALI.
Main Methods:
- Establishment of an LPS-induced ALI rat model and use of normal human bronchial epithelial (NHBE) cells.
- Measurement of inflammatory cytokines (TNF-α, IL-1β, IL-6) using ELISA.
- Assessment of miR-16 expression and its role in inflammation via gene manipulation (overexpression/silencing) and RT-qPCR.
- Investigation of the miR-16 and TLR4 interaction using bioinformatics (TargetScan) and luciferase reporter assays.
Main Results:
- miR-16 expression was significantly decreased in LPS-induced ALI lung tissues.
- miR-16 mimic transfection reduced pro-inflammatory cytokine levels (TNF-α, IL-1β, IL-6) in NHBE cells.
- miR-16 overexpression downregulated TLR4 expression, and luciferase assays confirmed direct targeting of TLR4 by miR-16.
- LPS treatment rescued the effect of miR-16 on TLR4 in NHBE cells.
Conclusions:
- miR-16 plays a protective role in LPS-induced inflammatory responses in NHBE cells.
- The mechanism involves the regulation of Toll-like receptor 4 (TLR4) by miR-16.
- miR-16 represents a novel therapeutic avenue for treating acute lung injury.
