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)-κB-associated histone acetylation activity in phorbol myristate acetate (PMA)-differentiated U937 cells.
Methods We examined the inhibitory effects of montelukast on TNF-α-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-α (10 ng/mL) in the presence or absence of montelukast (0.01–10 μm) 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-α-induced IL-8 release was examined pharmacologically using selective NF-κB/IKK2 (AS602868, 3 μm), (PD98059, 10 μm) and p38 mitogen activated protein kinase (MAPK) (SB203580, 1 μm) inhibitors. NF-κB DNA binding activity was measured by a DNA-binding ELISA-based assay. NF-κB-p65-associated histone acetyltransferase (HAT) activity was measured by immunoprecipitation linked to commercial flourescent HAT.
Results TNF-α-induced IL-8 release was suppressed by an NF-κB inhibitor but not by MEK or p38 MAPK inhibitors. Montelukast induced a concentration-dependent inhibition of TNF-α-induced IL-8 release and mRNA expression that reached a plateau at 0.1 μm without affecting cell viability. Montelukast did not affect NF-κB p65 activation as measured by DNA binding but suppressed NF-κB p65-associated HAT activity.
Conclusion Montelukast inhibits TNF-α-stimulated IL-8 expression through changes in NF-κB p65-associated HAT activity. Drugs targeting these enzymes may enhance the anti-inflammatory actions of montelukast.