title: Metformin inhibits HMGB1 release in LPS-treated RAW 264.7 cells and increases survival rate of endotoxaemic mice.
abstract: OBJECTIVE
  Recently, metformin, a well-known anti-diabetic drug, has been shown to possess anti-inflammatory activities. This study investigated the effect of metformin on the expression of pro-inflammatory cytokines including high mobility group box 1 (HMGB1) in lipopolysaccharide (LPS)-treated animals and cells.
  
  
  METHODS
  We investigated whether metformin inhibits the release of HMGB1 in LPS-treated RAW 264.7 cells and increases survival rate in endotoxaemic mice (lethal endotoxaemia was induced by an i.p. injection of LPS). This was achieved by a range of techniques including Western blotting, enzyme-linked immunosorbent assay, specific pharmacological inhibitors, knock out of α(1) -subunit of AMP-activated protein kinase (AMPK) and recombinant HMGB1.
  
  
  RESULTS
  Both pre- and post-treatment with metformin significantly improved survival of animals during lethal endotoxaemia (survival rate was monitored up to 2 weeks), decreased serum levels of tumour necrosis factor-alpha (TNF-α), interleukin-1β, HMGB1 expression and myeloperoxidase activity in lungs. However, metformin failed to improve survival in endotoxaemic animals that had additionally been treated with recombinant HMGB1. In an in vitro study, metformin dose-dependently inhibited production of pro-inflammatory cytokines and HMGB1 release. Metformin activated AMPK by its phosphorylation. Compound C (pharmacological inhibitor of AMPK) and siAMPKα1 reversed the anti-inflammatory effect of metformin in LPS-treated cells.
  
  
  CONCLUSIONS
  Our data indicate that metformin significantly attenuates the pro-inflammatory response induced by LPS both in vivo and in vitro. Metformin improved survival in a mouse model of lethal endotoxaemia by inhibiting HMGB1 release. AMPK activation was implicated as one of the mechanisms contributing to this inhibition of HMGB1 secretion.
authors.affiliation: Department of Pharmacology, School of Medicine and Institute of Health Sciences, Gyeongsang National University, Jinju, Korea.
authors.forename: Konstantin
authors.initials: K
authors.lastname: Tsoyi
authors.forename: Hwa Jin
authors.initials: HJ
authors.lastname: Jang
authors.forename: Irina Tsoy
authors.initials: IT
authors.lastname: Nizamutdinova
authors.forename: Young Min
authors.initials: YM
authors.lastname: Kim
authors.forename: Young Soo
authors.initials: YS
authors.lastname: Lee
authors.forename: Hye Jung
authors.initials: HJ
authors.lastname: Kim
authors.forename: Han Geuk
authors.initials: HG
authors.lastname: Seo
authors.forename: Jae Heun
authors.initials: JH
authors.lastname: Lee
authors.forename: Ki Churl
authors.initials: KC
authors.lastname: Chang
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D000818:Animals; D002478:Cells, Cultured; D016207:Cytokines / Q000037:antagonists & inhibitors / Q000378:metabolism; D019446:Endotoxemia / Q000139:chemically induced / Q000188:drug therapy* / Q000276:immunology / Q000378:metabolism; D024243:HMGB1 Protein / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism*; D053583:Interleukin-1beta / Q000037:antagonists & inhibitors / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008264:Macrophages / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism; D008297:Male; D008687:Metformin / Q000494:pharmacology*; D051379:Mice; D008807:Mice, Inbred BALB C; D009195:Peroxidase / Q000037:antagonists & inhibitors / Q000378:metabolism; D011720:Pyrazoles / Q000494:pharmacology; D011743:Pyrimidines / Q000494:pharmacology; D015996:Survival Rate; D014409:Tumor Necrosis Factor-alpha / Q000097:blood / Q000378:metabolism
chemical_list: D016207:Cytokines; D024243:HMGB1 Protein; D053583:Interleukin-1beta; D008070:Lipopolysaccharides; D011720:Pyrazoles; D011743:Pyrimidines; D014409:Tumor Necrosis Factor-alpha; C516138:dorsomorphin; D008687:Metformin; D009195:Peroxidase; D055372:AMP-Activated Protein Kinases