title: Ethyl pyruvate induces heme oxygenase-1 through p38 mitogen-activated protein kinase activation by depletion of glutathione in RAW 264.7 cells and improves survival in septic animals.
abstract: OBJECTIVE
  We investigated the molecular mechanism by which ethyl pyruvate (EP) induces heme oxygenase-1 (HO-1) in RAW 264.7 cells and its effect on survival rate in cecal ligation and puncture (CLP)-induced wild-type (WT) and HO-1 knockout (HO-1(-/-)) septic mice.
  
  
  RESULTS
  EP induced HO-1 in a dose- and time-dependent manner, which was mediated through p38 mitogen-activated protein kinase (MAPK) and NF-E2-related factor 2 (Nrf2) signaling cascade in RAW 264.7 cells. EP significantly inhibited the lipopolysaccharide (LPS)-stimulated inducible nitric oxide synthase (iNOS) expression and high-mobility group box 1 (HMGB1) release in RAW 264.7 cells. The inhibitory effect of EP on LPS-stimulated iNOS expression and HMGB1 release was reversed by transfection with siHO-1RNA in RAW 264.7 cells, but EP failed to reduce them in HO-1(-/-) peritoneal macrophages treated with LPS. Moreover, treatment of cells with glutathione ethyl ester (GSH-Et), SB203580 (p38 MAPK inhibitor), siHO-1, or p38-siRNA transfection inhibited anti-inflammatory effect of EP. Interestingly, both HO-1 induction and phosphorylation of p38 by EP were reversed by GSH-Et, and antioxidant redox element-luciferase activity by EP was reversed by SB203580 in LPS-activated cells. EP increased survival and decreased serum HMGB1 in CLP-WT mice, whereas it did not increase survival or decrease circulating HMGB1 in HO-1(-/-) CLP-mice.
  
  
  CONCLUSIONS
  Our work provides new insights into the understanding the molecular mechanism by showing that EP induces HO-1 through a p38 MAPK- and NRF2-dependent pathway by decreasing GSH cellular levels. We conclude that EP inhibits proinflammatory response to LPS in macrophages and increases survival in CLP-induced septic mice by upregulation of HO-1 level, in which p38 MAPK and Nrf2 play an important role.
authors.affiliation: Department of Pharmacology, School of Medicine, Institute of Health Sciences, Gyeongsang National University, Jinju, Korea.
authors.forename: Hwa Jin
authors.initials: HJ
authors.lastname: Jang
authors.forename: Young Min
authors.initials: YM
authors.lastname: Kim
authors.forename: Konstantin
authors.initials: K
authors.lastname: Tsoyi
authors.forename: Eun Jung
authors.initials: EJ
authors.lastname: Park
authors.forename: Young Soo
authors.initials: YS
authors.lastname: Lee
authors.forename: Hye Jung
authors.initials: HJ
authors.lastname: Kim
authors.forename: Jae Heun
authors.initials: JH
authors.lastname: Lee
authors.forename: Yeonsoo
authors.initials: Y
authors.lastname: Joe
authors.forename: Hun Taeg
authors.initials: HT
authors.lastname: Chung
authors.forename: Ki Churl
authors.initials: KC
authors.lastname: Chang
mesh_terms: D000818:Animals; D002460:Cell Line; D005978:Glutathione / Q000378:metabolism*; D024243:HMGB1 Protein / Q000235:genetics / Q000378:metabolism; D051547:Heme Oxygenase-1 / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D051267:NF-E2-Related Factor 2 / Q000235:genetics / Q000378:metabolism; D018805:Sepsis / Q000188:drug therapy*; D048051:p38 Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*
chemical_list: D024243:HMGB1 Protein; D051267:NF-E2-Related Factor 2; D051547:Heme Oxygenase-1; D048051:p38 Mitogen-Activated Protein Kinases; D005978:Glutathione