title: Daidzein suppresses pro-inflammatory chemokine Cxcl2 transcription in TNF-α-stimulated murine lung epithelial cells via depressing PARP-1 activity.
abstract: OBJECTIVE
  Daidzein (4',7-dihydroxyisoflavone) is an isoflavone exiting in many herbs that has shown anti-inflammation activity. The aim of this study was to investigate the mechanism underlying its anti-inflammatory action in murine lung epithelial cells.
  
  
  METHODS
  C57BL/6 mice were intranasally exposed to TNF-α to induce lung inflammation. The mice were injected with daidzein (400 mg/kg, ip) before TNF-α challenge, and sacrificed 12 h after TNF-α challenge, and lung tissues were collected for analyisis. In in vitro studies, murine MLE-12 epithelial cells were treated with TNF-α (20 ng/mL). The expression of pro-inflammatory chemokine Cxcl2 mRNA and NF-κB transcriptional activity were examined using real-time PCR and a dual reporter assay. Protein poly-adenosine diphosphate-ribosylation (PARylation) was detecyed using Western blotting and immunoprecipitation assays.
  
  
  RESULTS
  Pretreatment of the mice with daidzein markedly attenuated TNF-α-induced lung inflammation, and inhibited Cxcl2 expression in lung tissues. Furthermore, daidzein (10 μmol/L) prevented TNF-α-induced increases in Cxcl2 expression and activity and NF-κB transcriptional activity, and markedly inhibited TNF-α-induced protein PARylation in MLE-12 cells in vitro. In MLE-12 cells co-transfected with the PARP-1 expression plasmid and NF-κB-luc (or Cxcl2-luc) reporter plasmid, TNF-α markedly increased NF-κB (or Cxcl2) activation, which were significantly attenuated in the presence of daidzein (or the protein PARylation inhibitor PJ 34). PARP-1 activity assay showed that daidzein (10 μmol/L) reduced the activity of PARP-1 by ∼75%.
  
  
  CONCLUSIONS
  The anti-inflammatory action of daidzein in murine lung epithelial cells seems to be mediated via a direct interaction with PARP-1, which inhibits RelA/p65 protein PARylation required for the transcriptional modulation of pro-inflammatory chemokines such as Cxcl2.
authors.affiliation: 1] School of Pharmaceutical Science, Jilin University, Changchun 130021, China [2] Affiliated Hospital to Changchun University of Chinese Medicine, Changchun 130021, China.
authors.forename: Hai-yan
authors.initials: HY
authors.lastname: Li
authors.affiliation: Institute of Genetics and Cytology, Northeast Normal University, Changchun 130024, China.
authors.forename: Lang
authors.initials: L
authors.lastname: Pan
authors.affiliation: Institute of Genetics and Cytology, Northeast Normal University, Changchun 130024, China.
authors.forename: Yue-shuang
authors.initials: YS
authors.lastname: Ke
authors.affiliation: Institute of Genetics and Cytology, Northeast Normal University, Changchun 130024, China.
authors.forename: Enkhzaya
authors.initials: E
authors.lastname: Batnasan
authors.affiliation: School of Pharmaceutical Science, Jilin University, Changchun 130021, China.
authors.forename: Xiang-qun
authors.initials: XQ
authors.lastname: Jin
authors.affiliation: School of Pharmaceutical Science, Jilin University, Changchun 130021, China.
authors.forename: Zhong-ying
authors.initials: ZY
authors.lastname: Liu
authors.affiliation: Institute of Genetics and Cytology, Northeast Normal University, Changchun 130024, China.
authors.forename: Xue-qing
authors.initials: XQ
authors.lastname: Ba
mesh_terms: D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology*; D002460:Cell Line; D054426:Chemokine CXCL2 / Q000235:genetics / Q000378:metabolism*; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism; D017930:Genes, Reporter; D007529:Isoflavones / Q000494:pharmacology*; D008168:Lung / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism; D008297:Male; D008810:Mice, Inbred C57BL; D011014:Pneumonia / Q000139:chemically induced / Q000276:immunology / Q000378:metabolism / Q000517:prevention & control*; D000071137:Poly (ADP-Ribose) Polymerase-1; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D011065:Poly(ADP-ribose) Polymerases / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013997:Time Factors; D051996:Transcription Factor RelA / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects*; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha
chemical_list: D000893:Anti-Inflammatory Agents; D054426:Chemokine CXCL2; C404915:Cxcl2 protein, mouse; D004791:Enzyme Inhibitors; D007529:Isoflavones; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D012333:RNA, Messenger; C498144:Rela protein, mouse; D051996:Transcription Factor RelA; D014409:Tumor Necrosis Factor-alpha; C004742:daidzein; C499321:Parp1 protein, mouse; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases