Azelastine inhibits secretion of IL-6, TNF-alpha and IL-8 as well as NF-kappaB activation and intracellular calcium ion levels in normal human mast cells

BACKGROUND: Mast cells are involved in allergic inflammation by secreting histamine, proteases and several cytokines, including interleukin (IL)-6, tumor necrosis factor-alpha (TNF-alpha) and IL-8. Certain histamine-1 receptor antagonists, such as azelastine present in the ophthalmic solution Optivar, have been reported to inhibit histamine and tryptase secretion, but its effect on inflammatory cytokine release from normal human umbilical cord blood-derived cultured mast cells (hCBMC) are not well known. METHODS: We investigated the effect of azelastine on the secretion of IL-6, TNF-alpha and IL-8 from hCBMC, as well as its possible mechanism of action. hCBMC sensitized with IgE were pretreated for 5 min with azelastine at 0.01, 0.1, 1, 3, 6, 12, 24, or 60 microM of Optivar, before stimulation with anti-IgE for 6 h. Optivar vehicle without azelastine was used as control. Cytokines were measured by ELISA, intracellular calcium levels by calcium indicators confocal, and nuclear factor-kappaB (NF-kappaB) by electromobility shift assay. RESULTS: Stimulation with anti-IgE led to substantial secretion of IL-6, TNF-alpha and IL-8. Preincubation for 5 min resulted in almost maximal inhibition with 6 microM azelastine for TNF-alpha (80%), with 24 microM for IL-6 (83%) and 60 microM for IL-8 (99%); the vehicle solution at the same concentrations as Optivar had no effect. Stimulation with anti-IgE increased intracellular Ca2+ level and induced NF-kappaB expression in hCBMC, which was inhibited by 24 microM azelastine. CONCLUSION: Azelastine inhibited hCBMC secretion of IL-6, TNF-alpha and IL-8, possibly by inhibiting intracellular Ca2+ ions and NF-kappaB activation. Azelastine may, therefore, be helpful in treating allergic inflammation.