K2P Channel Inhibition Enhances Allergen‐Induced ATP Release by a Mechanism Involving PKC Activation in Human Bronchial Epithelial Cells

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Allergens derived from the common fungus Alternaria alternata induce oxidative stress in human airway epithelial (HBE) cells that leads to the regulated release of ATP and subsequent activation of P2X7 receptors that facilitate Ca2+ uptake into the cell. Sustained increases in [Ca2+]i are required for nuclear processing and secretion of IL‐33, which initiates allergic inflammation by activating ST2 receptors on immune cells to induce Th2 cytokine secretion. Pretreatment of HBE cells with the K2P channel blockers bupivacaine or quinidine produced a significant increase in ATP release following Alternaria stimulation. This response was blocked by inhibiting ATP loading into membrane vesicles by treatment with 200 nM bafilomycin A1 before allergen exposure. Similarly, pretreatment with the PKC inhibitor Go6976 also blocked approximately 50% of Alternaria‐induced ATP release and completely abolished the increase in ATP release produced by pretreatment with K2P channel blockers. The effects of bupivacaine and quinidine were comparable to the effect of phorbol 12‐myristate 13‐acetate (PMA, 2 mM), a well‐characterized PKC activating compound prior to Alternaria stimulation. These results support the conclusion that K2P channel inhibition is associated with PKC activation, which functions to potentiate the effects of Alternaria allergens on vesicular ATP release. We propose that enhanced PKC activity is dependent on membrane depolarization associated with inhibition of constitutive, K2P channel mediated K+ efflux from these cells.Support or Funding InformationThis study was supported by grants from the NIH (R01‐AI128729), awarded to HK and SMO and from the Minnesota Agriculture Experiment Station (AES‐0016097) awarded to SMO.