title: [Impact of H₂S on oxidized-low density lipoprotein-stimulated nuclear factor-κB in human monocytes/macrophage and its mechanisms].
abstract: OBJECTIVE
  To investigate the role of hydrogen sulfide (H₂S) on oxidized-low density lipoprotein (ox-LDL)-stimulated NF-κB pathway in human monocytes/macrophages and its mechanisms.
  
  
  METHODS
  THP-1 cells were induced to differentiate into macrophages by incubation with phorbol myristate acetate (PMA) . The human monocytes/macrophages were divided into 4 groups: control group, ox-LDL group, ox-LDL + H₂S 100 μmol/L group and ox-LDL + H₂S 500 μmol/L group. The expression of IκBα and phosphorylation of NF-κB p65 in the cells were detected by Western blotting. The expression of IκBα and nuclear translocation of NF-κB p65 in the cells were observed by laser confocal method. The interaction between NF-κB p65 and IκBα in the nuclear extracts was detected by coimmunoprecipitation method.
  
  
  RESULTS
  Compared with the control group, the phosphorylation of NF-κB p65 in the human monocytes/macrophages of ox-LDL group was increased significantly (0.855 ± 0.116 vs. 0.502 ± 0.218, P=0.046), while the expression of IκBα in the cells of the ox-LDL group was decreased (0.612 ± 0.216 vs. 0.997 ± 0.167, P=0.029). Compared with the ox-LDL group, the phosphorylation of NF-κB p65 in the cells of the ox-LDL + H₂S 100 μmol/L group and the ox-LDL + H₂S 500 μmol/L group was decreased significantly (0.424 ± 0.225 vs. 0.855 ± 0.116, P=0.020; 0.378 ± 0.071 vs. 0.855 ± 0.116, P=0.011, respectively), while the expressions of IκBα in the cells of the ox-LDL + H₂S 100 μmol/L group and the ox-LDL + H₂S 500 μmol/L group were increased (1.037 ± 0.111 vs. 0.612 ± 0.216, P=0.015; 1.046 ± 0.084 vs. 0.612 ± 0.216, P=0.013, respectively). The results from laser confocal method demonstrated that the IκBα expression in the cytoplasma of cells in the ox-LDL group was lower than that in the control group, and the nuclear translocation of NF-κB p65 in the cells of the ox-LDL group was higher than that in the control group. The IκBα expression in the cytoplasma of cells in the ox-LDL+ H₂S 100 μmol/L group and ox-LDL + H₂S 500 μmol/L group was higher than that in the ox-LDL group, and the nuclear translocation of NF-κB p65 in the cells of ox-LDL group was lower than that in the ox-LDL group. The coimmunoprecipitation experiment showed that no IκBα integrated with NF-κB p65 was detected in the nuclear extracts of cells in the control group, a small amount of IκBα integrated with NF-κB p65 was detected in the nuclear extracts of cells in the ox-LDL group, but a large amount of IκBα integrated with NF-κB p65 was detected in the nuclear extracts of cells in the ox-LDL+H₂S 100 μmol/L group and the ox-LDL + H₂S 500 μmol/L group.
  
  
  CONCLUSIONS
  H₂S inhibited the activation of NF-κB p65 pathway in the ox-LDL-induced human monocytes/macrophages. The mechanisms might involve the prevention of the degradation of IκBα, then the inhibition of the phosphorylation and nuclear translocation of NF-κB p65, thus promoting the IκBα integrated with NF-κB p65 in the nuclei, and then inhibiting the activity of NF-κB.
authors.affiliation: Department of Pediatrics, Peking University First Hospital, Beijing 100034, China.
authors.forename: Man-man
authors.initials: MM
authors.lastname: Zhao
authors.forename: Qiao-li
authors.initials: QL
authors.lastname: Zhang
authors.forename: Hui
authors.initials: H
authors.lastname: Yan
authors.forename: Jun-bao
authors.initials: JB
authors.lastname: DU
authors.forename: Bin
authors.initials: B
authors.lastname: Geng
authors.forename: Chao-shu
authors.initials: CS
authors.lastname: Tang
authors.forename: Hong-fang
authors.initials: HF
authors.lastname: Jin
mesh_terms: D002460:Cell Line; D006801:Humans; D006862:Hydrogen Sulfide / Q000494:pharmacology*; D020672:I-kappa B Proteins / Q000378:metabolism; D008077:Lipoproteins, LDL / Q000494:pharmacology*; D008264:Macrophages / Q000378:metabolism*; D009000:Monocytes / Q000378:metabolism*; D000072000:NF-KappaB Inhibitor alpha; D015398:Signal Transduction / Q000187:drug effects; D051996:Transcription Factor RelA / Q000378:metabolism*
chemical_list: D020672:I-kappa B Proteins; D008077:Lipoproteins, LDL; C000606204:NFKBIA protein, human; C498143:RELA protein, human; D051996:Transcription Factor RelA; C099252:oxidized low density lipoprotein; D000072000:NF-KappaB Inhibitor alpha; D006862:Hydrogen Sulfide