Azelastine inhibits secretion of IL-6, TNF-α and IL-8 as well as NF-κB 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-α (TNF-α) 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-α 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 μM 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-κB (NF-κB) by electromobility shift assay. Results: Stimulation with anti-IgE led to substantial secretion of IL-6, TNF-α and IL-8. Preincubation for 5 min resulted in almost maximal inhibition with 6 μM azelastine for TNF-α (80%), with 24 μM for IL-6 (83%) and 60 μM 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-κB expression in hCBMC, which was inhibited by 24 μM azelastine. Conclusion: Azelastine inhibited hCBMC secretion of IL-6, TNF-α and IL-8, possibly by inhibiting intracellular Ca²⁺ ions and NF-κB activation. Azelastine may, therefore, be helpful in treating allergic inflammation.