The airway epithelium plays a critical role in innate responses to airborne allergens by secreting IL-1 family cytokines such as IL-1α and IL-33 as alarmins that subsequently orchestrate appropriate immune responses. Previous studies revealed that epithelial IL-33 secretion by allergens such as Alternaria alternata or house dust mite involves Ca²⁺-dependent signaling, via initial activation of ATP-stimulated P2YR2 (type 2 purinoceptor) and subsequent activation of the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase DUOX1. We sought to identify proximal mechanisms by which epithelial cells sense these allergens and here highlight the importance of PAR2 (protease-activated receptor 2) and TRP (transient receptor potential) Ca²⁺ channels such as TRPV1 (TRP vanilloid 1) in these responses. Combined studies of primary human nasal and mouse tracheal epithelial cells, as well as immortalized human bronchial epithelial cells, indicated the importance of both PAR2 and TRPV1 in IL-33 secretion by both Alternaria alternata and house dust mite, based on both pharmacological and genetic approaches. TRPV1 was also critically involved in allergen-induced ATP release, activation of DUOX1, and redox-dependent activation of EGFR (epidermal growth factor receptor). Moreover, genetic deletion of TRPV1 dramatically attenuated allergen-induced IL-33 secretion and subsequent type 2 responses in mice in vivo. TRPV1 not only contributed to ATP release and P2YR2 signaling but also was critical in downstream innate responses to ATP, indicating potentiating effects of P2YR2 on TRPV1 activation. In aggregate, our studies illustrate a complex relationship between various receptor types, including PAR2 and P2YR2, in epithelial responses to asthma-relevant airborne allergens and highlight the central importance of TRPV1 in such responses.

气道上皮细胞通过分泌 IL-1 家族细胞因子（如 IL-1α 和 IL-33）作为随后协调适当免疫反应的警报素，在对空气传播的过敏原的先天反应中起着关键作用。先前的研究表明，通过 ATP 刺激的 P2YR2（2 型嘌呤受体）的初始激活和烟酰胺磷酸腺嘌呤二核苷酸的后续激活，过敏原（如链格孢或屋尘螨）的上皮细胞分泌 IL-33 涉及 Ca ²⁺依赖性信号传导（ NADPH) 氧化酶 DUOX1。我们试图确定上皮细胞感知这些过敏原的近端机制，并在此强调 PAR2（蛋白酶激活受体 2）和 TRP（瞬时受体电位）Ca ^{2+的重要性}这些反应中的通道，例如 TRPV1（TRP 香草素 1）。基于药理学和遗传学方法，对原代人鼻和小鼠气管上皮细胞以及永生化人支气管上皮细胞的联合研究表明，PAR2 和 TRPV1 在链格孢和屋尘螨分泌 IL-33 中的重要性. TRPV1 还与过敏原诱导的 ATP 释放、DUOX1 的激活和 EGFR（表皮生长因子受体）的氧化还原依赖性激活密切相关。此外，TRPV1 的基因缺失显着减弱了小鼠体内过敏原诱导的 IL-33 分泌和随后的 2 型反应. TRPV1 不仅有助于 ATP 释放和 P2YR2 信号传导，而且在下游对 ATP 的先天反应中也至关重要，表明 P2YR2 对 TRPV1 激活的增强作用。总的来说，我们的研究说明了各种受体类型（包括 PAR2 和 P2YR2）在上皮对哮喘相关空气传播过敏原的反应中的复杂关系，并强调了 TRPV1 在此类反应中的核心重要性。