title: Montelukast inhibits tumour necrosis factor-alpha-mediated interleukin-8 expression through inhibition of nuclear factor-kappaB p65-associated histone acetyltransferase activity.
abstract: BACKGROUND
  Montelukast is a potent cysteinyl leukotriene-1 receptor antagonist possessing some anti-inflammatory effects although the molecular mechanism of these anti-inflammatory effects is unknown. In this study, we aimed to investigate the effect of montelukast on nuclear factor (NF)-kappaB-associated histone acetylation activity in phorbol myristate acetate (PMA)-differentiated U937 cells.
  
  
  METHODS
  We examined the inhibitory effects of montelukast on TNF-alpha-induced IL-8 production in PMA-differentiated U-937 cells. U-937 cells were exposed to PMA (50 ng/mL) for 48 h to allow differentiation to macrophages. Macrophages were then exposed to TNF-alpha (10 ng/mL) in the presence or absence of montelukast (0.01-10 microm) for 24 h. After this time, the concentration of IL-8 in the culture supernatant was measured by sandwich-type ELISA kit. The effect of signalling pathways on TNF-alpha-induced IL-8 release was examined pharmacologically using selective NF-kappaB/IKK2 (AS602868, 3 microm), (PD98059, 10 microm) and p38 mitogen activated protein kinase (MAPK) (SB203580, 1 microm) inhibitors. NF-kappaB DNA binding activity was measured by a DNA-binding ELISA-based assay. NF-kappaB-p65-associated histone acetyltransferase (HAT) activity was measured by immunoprecipitation linked to commercial fluorescent HAT.
  
  
  RESULTS
  TNF-alpha-induced IL-8 release was suppressed by an NF-kappaB inhibitor but not by MEK or p38 MAPK inhibitors. Montelukast induced a concentration-dependent inhibition of TNF-alpha-induced IL-8 release and mRNA expression that reached a plateau at 0.1 microm without affecting cell viability. Montelukast did not affect NF-kappaB p65 activation as measured by DNA binding but suppressed NF-kappaB p65-associated HAT activity.
  
  
  CONCLUSIONS
  Montelukast inhibits TNF-alpha-stimulated IL-8 expression through changes in NF-kappaB p65-associated HAT activity. Drugs targeting these enzymes may enhance the anti-inflammatory actions of montelukast.
authors.affiliation: Department of Pediatric Allergy, Erciyes University School of Medicine, Kayseri, Turkey. tahanfulya@yahoo.com
authors.forename: F
authors.initials: F
authors.lastname: Tahan
authors.forename: E
authors.initials: E
authors.lastname: Jazrawi
authors.forename: T
authors.initials: T
authors.lastname: Moodley
authors.forename: G E
authors.initials: GE
authors.lastname: Rovati
authors.forename: I M
authors.initials: IM
authors.lastname: Adcock
mesh_terms: D000085:Acetates / Q000494:pharmacology*; D003521:Cyclopropanes; D051548:Histone Acetyltransferases / Q000037:antagonists & inhibitors*; D006801:Humans; D016209:Interleukin-8 / Q000187:drug effects* / Q000378:metabolism; D020024:Leukotriene Antagonists / Q000494:pharmacology*; D008264:Macrophages / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D011804:Quinolines / Q000494:pharmacology*; D015398:Signal Transduction; D013440:Sulfides; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D020298:U937 Cells
chemical_list: D000085:Acetates; D003521:Cyclopropanes; D016209:Interleukin-8; D020024:Leukotriene Antagonists; D016328:NF-kappa B; D011804:Quinolines; D013440:Sulfides; D014409:Tumor Necrosis Factor-alpha; D051548:Histone Acetyltransferases; C093875:montelukast