Wu Liping, Oshima Tadayuki, Shan Jing, Sei Hiroo, Tomita Toshihiko, Ohda Yoshio, Fukui Hirokazu, Watari Jiro, Miwa Hiroto
Division of Gastroenterology, Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Japan; and Department of Gastroenterology, The Third People's Hospital of Chengdu, Chengdu, China.
Division of Gastroenterology, Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Japan; and
Am J Physiol Gastrointest Liver Physiol. 2015 Oct 15;309(8):G695-702. doi: 10.1152/ajpgi.00162.2015. Epub 2015 Aug 20.
Esophageal visceral hypersensitivity has been proposed to be the pathogenesis of heartburn sensation in nonerosive reflux disease. Protease-activated receptor-2 (PAR-2) is expressed in human esophageal epithelial cells and is believed to play a role in inflammation and sensation. PAR-2 activation may modulate these responses through adenosine triphosphate (ATP) release, which is involved in transduction of sensation and pain. The transient receptor potential vanilloid receptor 1 (TRPV1) and acid-sensing ion channels (ASICs) are both acid-sensitive nociceptors. However, the interaction among these molecules and the mechanisms of heartburn sensation are still not clear. We therefore examined whether ATP release in human esophageal epithelial cells in response to acid is modulated by TRPV1 and ASICs and whether PAR-2 activation influences the sensitivity of TRPV1 and ASICs. Weak acid (pH 5) stimulated the release of ATP from primary human esophageal epithelial cells (HEECs). This effect was significantly reduced after pretreatment with 5-iodoresiniferatoxin (IRTX), a TRPV1-specific antagonist, or with amiloride, a nonselective ASIC blocker. TRPV1 and ASIC3 small interfering RNA (siRNA) transfection also decreased weak acid-induced ATP release. Pretreatment of HEECs with trypsin, tryptase, or a PAR-2 agonist enhanced weak acid-induced ATP release. Trypsin treatment led to the phosphorylation of TRPV1. Acid-induced ATP release enhancement by trypsin was partially blocked by IRTX, amiloride, or a PAR-2 antagonist. Conversely, acid-induced ATP release was augmented by PAR-2 activation through TRPV1 and ASICs. These findings suggested that the pathophysiology of heartburn sensation or esophageal hypersensitivity may be associated with the activation of PAR-2, TRPV1, and ASICs.
食管内脏高敏感性被认为是非糜烂性反流病中烧心感的发病机制。蛋白酶激活受体-2（PAR-2）在人食管上皮细胞中表达，并且被认为在炎症和感觉中起作用。PAR-2激活可能通过三磷酸腺苷（ATP）释放来调节这些反应，而ATP释放参与感觉和疼痛的传导。瞬时受体电位香草酸受体1（TRPV1）和酸敏感离子通道（ASICs）都是酸敏感的伤害感受器。然而，这些分子之间的相互作用以及烧心感的机制仍不清楚。因此，我们研究了酸刺激下人食管上皮细胞中ATP释放是否受TRPV1和ASICs调节，以及PAR-2激活是否影响TRPV1和ASICs的敏感性。弱酸（pH 5）刺激原代人食管上皮细胞（HEECs）释放ATP。用TRPV1特异性拮抗剂5-碘树脂毒素（IRTX）或非选择性ASIC阻滞剂阿米洛利预处理后，这种效应显著降低。TRPV1和ASIC3小干扰RNA（siRNA）转染也减少了弱酸诱导的ATP释放。用胰蛋白酶、类胰蛋白酶或PAR-2激动剂预处理HEECs可增强弱酸诱导的ATP释放。胰蛋白酶处理导致TRPV1磷酸化。胰蛋白酶引起的酸诱导ATP释放增强被IRTX、阿米洛利或PAR-2拮抗剂部分阻断。相反，PAR-2激活通过TRPV1和ASICs增强酸诱导的ATP释放。这些发现表明，烧心感或食管高敏感性的病理生理学可能与PAR-2、TRPV1和ASICs的激活有关。
