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J Biol Chem. 2014 Aug 15;289(33):23246-55. doi: 10.1074/jbc.M114.577908. Epub 2014 Jun 27.

Metformin suppresses lipopolysaccharide (LPS)-induced inflammatory response in murine macrophages via activating transcription factor-3 (ATF-3) induction.

Author information

1
From the Department of Pharmacology and Pharmaceutical Sciences and.
2
Department of Molecular Medicine, Lee Gil Ya Cancer and Diabetes Institute, Gachon University, Incheon 406-799, Republic of Korea.
3
Bioorganic Science Division, Korea Research Institute of Chemical Technology, Taejeon, 305-343, Republic of Korea, and.
4
From the Department of Pharmacology and Pharmaceutical Sciences and Gachon Medical Research Institute, Gil Medical Center, Incheon 405-760, Republic of Korea hgcheon@gachon.ac.kr.

Abstract

Metformin, a well known antidiabetic agent that improves peripheral insulin sensitivity, also elicits anti-inflammatory actions, but its mechanism is unclear. Here, we investigated the mechanism responsible for the anti-inflammatory effect of metformin action in lipopolysaccharide (LPS)-stimulated murine macrophages. Metformin inhibited LPS-induced production of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in a concentration-dependent manner and in parallel induction of activating transcription factor-3 (ATF-3), a transcription factor and member of the cAMP-responsive element-binding protein family. ATF-3 knockdown abolished the inhibitory effects of metformin on LPS-induced proinflammatory cytokine production accompanied with reversal of metformin-induced suppression of mitogen-activated protein kinase (MAPK) phosphorylation. Conversely, AMP-activated protein kinase (AMPK) phosphorylation and NF-κB suppression by metformin were unaffected by ATF-3 knockdown. ChIP-PCR analysis revealed that LPS-induced NF-κB enrichments on the promoters of IL-6 and TNF-α were replaced by ATF-3 upon metformin treatment. AMPK knockdown blunted all the effects of metformin (ATF-3 induction, proinflammatory cytokine inhibition, and MAPK inactivation), suggesting that AMPK activation by metformin is required for and precedes ATF-3 induction. Oral administration of metformin to either mice with LPS-induced endotoxemia or ob/ob mice lowered the plasma and tissue levels of TNF-α and IL-6 and increased ATF-3 expression in spleen and lungs. These results suggest that metformin exhibits anti-inflammatory action in macrophages at least in part via pathways involving AMPK activation and ATF-3 induction.

KEYWORDS:

ATF-3; Inflammation; Interleukin 6 (IL-6); Lipopolysaccharide (LPS); Macrophage; Metformin; Tumor Necrosis Factor (TNF)

PMID:
24973221
PMCID:
PMC4132821
DOI:
10.1074/jbc.M114.577908
[Indexed for MEDLINE]
Free PMC Article

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