Pranlukast inhibits NF-κB activation in human monocytes/macrophages and T cells

Background Pranlukast is a leukotriene 1 (LT1) receptor antagonist and is effective against bronchial asthma. Pranlukast inhibits contraction of the tracheal muscle, and thereby antagonizes the binding of LTC4, LTD4 and LTE4. However, the action of pranlukast on monocytes/macrophages and T cells is unknown. Objective We examined whether or not pranlukast inhibits TNF-alpha-induced activation of nuclear transcription factor NF-kappaB, a factor that is essential for the expression of proinflammatory cytokines, on human monocytic 1.3% dimethylsulphoxide (DMSO)-differentiated U-937 cells, which have cysteinyl LT1 (CysLT1) receptors on their membranes, and T cells (Jurkat), which do not. Methods We examined whether or not LTC4, LTD4 or LTE4 induced NF-kappaB activation in 1.3% DMSO-differentiated U-937 cells by Western blotting. The inhibitory effects of pranlukast and MK-571, which is an LTD4 receptor-selective antagonist, on TNF-alpha-induced NF-kappaB activation was evaluated by Western blotting and flow cytometry, and those on lipopolysaccharide (LPS)-induced interleukin-6 (IL-6) production in peripheral blood mononuclear cells (PBMC) were evaluated by enzyme-linked immunosorbent assaying. Results LTC4, LTD4 or LTE4 did not induce NF-kappaB activation in 1.3% DMSO-differentiated U-937 cells. Western blotting demonstrated that 10(-5) M pranlukast inhibits NF-kappaB activation in 1.3% DMSO-differentiated U-937 and Jurkat cells by about 40% & 30%, respectively. Flow cytometry demonstrated that pranlukast and MK-571 inhibit NF-kappaB activation in 1.3% DMSO-differentiated U-937 and Jurkat cells in a dose-related manner. Moreover, 10(-5) M pranlukast and MK-571 inhibited LPS-induced IL-6 production in PBMC by about 65% and 15%, respectively. Conclusion Pranlukast and MK-571 partially inhibited NF-kappaB activation in 1.3% DMSO- differentiated U-937 and Jurkat cells, and IL-6 release in PBMC. These findings are consistent with the idea that, independently of CysLT1 receptor antagonism, micromolar concentrations of pranlukast suppress the production of proinflammatory cytokines via inhibition of NF-kappaB activation in monocytes/macrophages and T cells, but the contribution of this effect to the anti-inflammatory activity of pranlukast at oral therapeutic doses in asthmatic patients is unclear.