Respiratory Pharmacology Group, Airway Disease, National Heart and Lung Institute, Imperial College London, London, UK.
Research and Early Development, Respiratory and Immunology, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden.
Eur Respir J. 2020 Jul 2;56(1). doi: 10.1183/13993003.01458-2019. Print 2020 Jul.
Mast cell-airway smooth muscle (ASM) interactions play a major role in the immunoglobulin (Ig)E- dependent bronchoconstriction seen in asthma but less is known about IgE-independent mechanisms of mast cell activation. Transient receptor potential cation channel, subfamily V, member 4 (TRPV4) activation causes contraction of human ASM the release of cysteinyl leukotrienes (cysLTs) but the mechanism is unknown. The objective of the present study was to investigate a role for IgE-independent, mast cell-ASM interaction in TRPV4-induced bronchospasm.Bronchoconstriction was measured in anaesthetised guinea pigs and contraction of human and guinea-pig airway tissue assessed using isometric tension measurements. Increases in intracellular [Ca] were imaged using the Ca-sensitive dye FURA2, and time-lapse ptychography was utilised as a surrogate for contraction of ASM cells.The TRPV4 agonist GSK1016790A caused contraction in the guinea pig, and in human and guinea-pig tracheal tissue, which was inhibited by the TRPV4 antagonist GSK2193874. GSK1016790A increased [Ca] and released ATP in human ASM cells without causing contraction. TRPV4 and ATP evoked contraction in isolated tracheal tissue but co-culture experiments indicated a requirement for human lung mast cells. Expression profiling and pharmacological studies demonstrated that mast cell activation was dependent upon ATP activating the P2X4 receptor. Trypsin was shown to evoke contraction of tracheal tissue activation of PAR-2-TRPV4-ATP-cysLT axis indicating the potential disease relevance of this signalling pathway.TRPV4 activation increases [Ca] and releases ATP from ASM cells triggering P2X4-dependent release of cysLTs from mast cells resulting in ASM contraction. This study delineates a novel mast cell-ASM interaction and TRPV4 as a driver of IgE-independent mast cell-dependent bronchospasm.
肥大细胞-气道平滑肌（ASM）相互作用在哮喘中 IgE 依赖性支气管收缩中起主要作用，但对于 IgE 非依赖性肥大细胞激活机制知之甚少。瞬时受体电位阳离子通道，亚家族 V，成员 4（TRPV4）的激活会导致人 ASM 的收缩-胱天蛋白酶白三烯（cysLTs）的释放，但机制尚不清楚。本研究的目的是研究 TRPV4 诱导的支气管痉挛中 IgE 非依赖性、肥大细胞-ASM 相互作用的作用。在麻醉的豚鼠中测量支气管收缩，并使用等长张力测量法评估人源和豚鼠气道组织的收缩。使用 Ca 敏感染料 FURA2 成像细胞内[Ca]的增加，并利用时程相衬术作为 ASM 细胞收缩的替代物。TRPV4 激动剂 GSK1016790A 引起豚鼠、人和豚鼠气管组织的收缩，TRPV4 拮抗剂 GSK2193874 可抑制该收缩。GSK1016790A 增加[Ca]并在人 ASM 细胞中释放 ATP，而不引起收缩。TRPV4 和 ATP 在分离的气管组织中引起收缩，但共培养实验表明需要人肺肥大细胞。表达谱分析和药理学研究表明，肥大细胞的激活依赖于 ATP 激活 P2X4 受体。胰蛋白酶被证明可引起气管组织收缩和 PAR-2-TRPV4-ATP-cysLT 轴的激活，表明该信号通路具有潜在的疾病相关性。TRPV4 激活增加[Ca]并从 ASM 细胞中释放 ATP，触发 P2X4 依赖性肥大细胞释放 cysLTs，导致 ASM 收缩。本研究描绘了一种新的肥大细胞-ASM 相互作用和 TRPV4 作为 IgE 非依赖性肥大细胞依赖性支气管痉挛的驱动因素。
