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Published on: December 17, 2016
Effect of A-769662, a direct AMPK activator, on Tlr-4 expression and activity in mice heart tissue
Maryam Rameshrad1, Nasrin Maleki-Dizaji2, Hamid Soraya3
1Department of Pharmacology and Toxicology, Faculty of Pharmacy, Tabriz University of Medical Sciences, Tabriz, Iran; Student Research Committee, Faculty of Pharmacy, Tabriz University of Medical Sciences, Tabriz, Iran.
Objectives:
TLR-4 activates a number of inflammatory signaling pathways. Also, AMPK could be involved in anti-inflammatory signaling. The aim of this study was to identify whether stimulation of AMPK could inhibit LPS-induced Tlr-4 gene expression in mice hearts.
Materials And Methods:
Heart AMPK activity and/or Tlr-4 expression was stimulated in different mice groups, using respectively IP injection of A-769662 (10 mg/kg) and LPS (2 mg/kg) or a combination of both agents. Moreover, compound-C (20 mg/kg), as an AMPK antagonist, was intraperitoneally co-administrated with both A-769662 and LPS in another group to investigate the role of AMPK activity on Tlr-4 regulation. After 8 hr, in addition to peripheral neutrophil cell count, myocardial p-AMPK, p-ACC as well as MyD88 protein contents and Tlr-4 expression was assessed by Western blotting and real-time qRT-PCR, respectively. TNF-α and IL-6 expression levels were also determined by ELISA.
Results:
LPS induced heart Tlr-4 expression (P<0.001) associating with an increase in the myocardial MyD88 protein content (P<0.001), elevation of heart TNF-α (P<0.01) and IL-6 (P<0.05) concentrations, and rise in the peripheral neutrophil cell count (P<0.001). Administration of A-769662 decreased LPS-induced Tlr-4 expression (P<0.01) and alleviated peripheral neutrophil cell count (P<0.01). The inhibitory effect of A-769662 on LPS-induced Tlr-4 expression was reversed by antagonizing AMPK with compound-C (P<0.001) which reduced p-AMPK (P<0.05) and p-ACC (P<0.01) myocardial protein contents in the LPS+A-769662 group.
Conclusion:
This study demonstrated that activation of AMPK, by A-769662 agent, could inhibit Tlr-4 expression and activity, suggesting a link between AMPK and Tlr-4 in heart tissue.
Insights
Activation of AMP-activated protein kinase (AMPK) by A-769662 inhibits Toll-like receptor 4 (TLR-4) gene expression in mouse hearts. This suggests a potential therapeutic link between AMPK and TLR-4 in cardiac inflammation.
Area of Science:
- Cardiovascular Research
- Molecular Biology
- Immunology
Background:
- Toll-like receptor 4 (TLR-4) signaling pathways are activated during inflammation.
- AMP-activated protein kinase (AMPK) is implicated in anti-inflammatory processes.
- The interplay between AMPK and TLR-4 in cardiac tissue requires further elucidation.
Purpose of the Study:
- To investigate if AMPK stimulation can suppress lipopolysaccharide (LPS)-induced TLR-4 gene expression in mouse hearts.
- To explore the role of AMPK activity in regulating TLR-4 expression.
Main Methods:
- Mice were treated with A-769662 (AMPK activator) and/or LPS (to induce TLR-4 expression).
- Compound-C (AMPK antagonist) was co-administered to assess AMPK's role.
- Western blotting, qRT-PCR, and ELISA were used to measure protein and gene expression (p-AMPK, p-ACC, MyD88, TLR-4, TNF-α, IL-6) and neutrophil counts.
Main Results:
- LPS significantly increased TLR-4 expression, MyD88, TNF-α, IL-6, and neutrophil counts in the heart.
- A-769662 administration reduced LPS-induced TLR-4 expression and neutrophil counts.
- The inhibitory effect of A-769662 was reversed by compound-C, confirming AMPK's role in suppressing TLR-4.
Conclusions:
- AMPK activation by A-769662 effectively inhibits TLR-4 expression and activity in the heart.
- A significant link exists between AMPK and TLR-4 regulation within cardiac tissue.
- This study highlights a potential therapeutic strategy targeting the AMPK-TLR-4 axis for managing cardiac inflammation.
