Olopatadine inhibits TNFα release from human conjunctival mast cells

Background: Tumor necrosis factor-alpha (TNF alpha) release likely plays a crucial role in allergic ocular inflammation via increasing ICAM-1 on epithelial cells and triggering other proinflammatory events. The immediate and prolonged release of TNF alpha from human conjunctival mast cells in response to allergen challenge is potentially an important target for therapeutic intervention, yet the effect of ocular anti-allergic agents on this process has not been examined. Olopatadine (Patanol) is a clinically effective dual-action ophthalmic anti-allergic agent that has been shown to inhibit mast cell histamine, tryptase, and PGD(2) release in vitro and promote decreased H-1 receptor binding activity in vitro and functional H-1 receptor antagonism in vivo. Objective: To investigate the effect of olopatadine on TNF alpha release from anti-IgE antibody challenged purified human conjunctival mast cells. Methods: Human conjunctival mast cells were purified (>95%) from cadaveric tissues using a procedure combining enzymatic digestion and Percoll gradient centrifugation. These cells were incubated with olopatadine for 30 minutes then challenged with anti-IgE antibody for 90 minutes. Supernatants were analyzed for TNF alpha. Results: Purified human conjunctival mast cells responded to anti-IgE antibody challenge with TNF alpha release in a concentration dependent manner (optimum concentration was 10 mu g/mL). Olopatadine pre-incubation resulted in a dose-dependent decrease in anti-IgE antibody mediated TNF alpha release (IC50 = 13.1 mu M). At a concentration of 3 mM olopatadine reduced TNF alpha release to the level of unchallenged controls. Conclusion: Olopatadine inhibited anti-IgE antibody-mediated release of TNF alpha from human conjunctival mast cells. This effect could contribute to the long duration of anti-allergic activity reported for the drug.