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Inducing Acute Lung Injury in Mice by Direct Intratracheal Lipopolysaccharide Instillation
Published on: July 6, 2019
MicroRNA-499-5p targets SIRT1 to aggravate lipopolysaccharide-induced acute lung injury
1Department of Thoracic and Cardiovascular Surgery, Huangshi Central Hospital (Affiliated Hospital of Hubei Polytechnic University), Edong Healthcare Group, Huangshi, Hubei, China.
Abstract:
Acute lung injury (ALI) is a life-threatening disease without effective and specific therapeutic strategies except the life-supporting treatments. Inflammation and oxidative stress are essential for the progression of ALI. MicroRNA-499-5p (miR-499-5p) has multiple pathophysiological actions; however, its function and mechanisms in ALI remain elusive. Mice were intravenously injected with miR-499-5p agomir, antagomir or the negative controls for 3 consecutive days and then received a single intratracheal injection of lipopolysaccharide (LPS, 5 mg/kg) to generate ALI model. Twenty four hours prior to LPS injection, EX-527 (1 mg/kg) was applied to inhibit SIRT1 activity. We identified a significant upregulation of miR-499-5p in LPS-treated lung tissues. miR-499-5p antagomir prevented, while miR-499-5p agomir promoted inflammation, oxidative stress and ALI in LPS-treated mice. Further studies indicated that miR-499-5p directly bound to the 3'-untranslated region of Sirtuin 1 (Sirt1) and decreased its protein level. SIRT1 inhibition blocked miR-499-5p antagomir-mediated pulmonary protection against LPS injury. miR-499-5p targets SIRT1 to aggravate LPS-induced ALI and it is a promising therapeutic target for the treatment of ALI.
Insights
MicroRNA-499-5p (miR-499-5p) exacerbates acute lung injury (ALI) by targeting Sirtuin 1 (SIRT1). Inhibiting miR-499-5p shows therapeutic potential for ALI treatment.
Area of Science:
- Pulmonary Medicine
- Molecular Biology
- Biochemistry
Background:
- Acute lung injury (ALI) is a critical condition with limited treatment options, driven by inflammation and oxidative stress.
- The role of microRNA-499-5p (miR-499-5p) in the pathogenesis of ALI is not well understood.
- Sirtuin 1 (SIRT1) is implicated in cellular protection and inflammation modulation.
Purpose of the Study:
- To investigate the function and mechanism of miR-499-5p in lipopolysaccharide (LPS)-induced acute lung injury.
- To determine the relationship between miR-499-5p and SIRT1 in the context of ALI.
- To evaluate the therapeutic potential of targeting miR-499-5p for ALI treatment.
Main Methods:
- Establishment of a mouse model of ALI using lipopolysaccharide (LPS) injection.
- Administration of miR-499-5p agomir or antagomir to modulate miR-499-5p levels.
- Inhibition of SIRT1 activity using EX-527.
- Assessment of inflammatory markers, oxidative stress, and lung injury.
- Luciferase reporter assay to confirm direct binding of miR-499-5p to the 3'-untranslated region of Sirt1.
Main Results:
- LPS treatment significantly upregulated miR-499-5p expression in mouse lung tissues.
- miR-499-5p antagomir attenuated LPS-induced inflammation, oxidative stress, and ALI.
- Conversely, miR-499-5p agomir exacerbated ALI.
- miR-499-5p was found to directly target and downregulate SIRT1 protein levels.
- Inhibition of SIRT1 abrogated the protective effects of miR-499-5p antagomir against LPS-induced lung injury.
Conclusions:
- miR-499-5p plays a critical role in promoting inflammation, oxidative stress, and ALI progression.
- The mechanism involves direct targeting of SIRT1, leading to its downregulation.
- miR-499-5p acts as a pro-inflammatory mediator in LPS-induced ALI.
- Targeting miR-499-5p represents a promising therapeutic strategy for acute lung injury.
