Department of Medicine, Rhode Island Hospital, Providence, Rhode Island, USA.
Am J Physiol Gastrointest Liver Physiol. 2012 Sep 1;303(5):G635-45. doi: 10.1152/ajpgi.00097.2012. Epub 2012 Jul 12.
The pathogenesis of gastroesophageal reflux disease (GERD) remains elusive, but recent evidence suggests that early secretion of inflammatory cytokines and chemokines by the mucosa leads to influx of immune cells followed by tissue damage. We previously showed that exposure of esophageal mucosa to HCl causes ATP release, resulting in activation of acetyl-CoA:1-O-alkyl-sn-glycero-3-phosphocholine acetyltransferase (lyso-PAF AT), the enzyme responsible for the production of platelet-activating factor (PAF). In addition, HCl causes release of IL-8 from the esophageal mucosa. We demonstrate that esophageal epithelial cells secrete proinflammatory mediators in response to HCl and that this response is mediated by ATP. Monolayers of the human esophageal epithelial cell line HET-1A were exposed to acidified cell culture medium (pH 5) for 12 min, a total of seven times over 48 h, to simulate the recurrent acid exposure clinically occurring in GERD. HCl upregulated mRNA and protein expression for the acid-sensing transient receptor potential cation channel, subfamily vanilloid member 1 (TRPV1), lyso-PAF AT, IL-8, eotaxin-1, -2, and -3, macrophage inflammatory protein-1α, and monocyte chemoattractant protein-1. The chemokine profile secreted by HET-1A cells in response to repeated HCl exposure parallels similar findings in erosive esophagitis patients. In HET-1A cells, the TRPV1 agonist capsaicin reproduced these findings for mRNA of the inflammatory mediators lyso-PAF AT, IL-8, and eotaxin-1. These effects were blocked by the TRPV1 antagonists iodoresiniferatoxin and JNJ-17203212. These effects were imitated by direct application of ATP and blocked by the nonselective ATP antagonist suramin. We conclude that HCl/TRPV-induced ATP release upregulated secretion of various chemoattractants by esophageal epithelial cells. These chemoattractants are selective for leukocyte subsets involved in acute inflammatory responses and allergic inflammation. The data support the validity of HET-1A cells as a model of the response of the human esophageal mucosa in GERD.
胃食管反流病（GERD）的发病机制仍然难以捉摸，但最近的证据表明，粘膜早期分泌炎症细胞因子和趋化因子会导致免疫细胞涌入，进而导致组织损伤。我们之前曾表明，食管粘膜暴露于 HCl 会导致 ATP 释放，从而激活乙酰辅酶 A：1-O-烷基-sn-甘油-3-磷酸胆碱乙酰转移酶（溶血血小板激活因子 AT），该酶负责产生血小板激活因子（PAF）。此外，HCl 会导致食管粘膜释放 IL-8。我们证明，食管上皮细胞会对 HCl 作出反应，分泌促炎介质，而这种反应是由 ATP 介导的。将人食管上皮细胞系 HET-1A 的单层暴露于酸化的细胞培养基（pH5）中 12 分钟，总共在 48 小时内重复七次，以模拟 GERD 中临床上反复出现的酸性暴露。HCl 上调了酸感应瞬时受体电位阳离子通道香草素 1 亚家族（TRPV1）、溶血血小板激活因子 AT、IL-8、嗜酸性粒细胞趋化因子-1、-2 和-3、巨噬细胞炎症蛋白-1α和单核细胞趋化蛋白-1 的 mRNA 和蛋白表达。HET-1A 细胞对重复 HCl 暴露的趋化因子谱与糜烂性食管炎患者的类似发现相平行。在 HET-1A 细胞中，TRPV1 激动剂辣椒素复制了这些促炎介质溶血血小板激活因子 AT、IL-8 和嗜酸性粒细胞趋化因子-1 的 mRNA。这些作用被 TRPV1 拮抗剂碘代异硫氰酸酯和 JNJ-17203212 阻断。直接应用 ATP 可以模拟这些作用，并被非选择性 ATP 拮抗剂苏拉明阻断。我们得出结论，HCl/TRPV1 诱导的 ATP 释放上调了食管上皮细胞各种趋化因子的分泌。这些趋化因子是参与急性炎症反应和过敏性炎症的白细胞亚群的选择性趋化因子。这些数据支持 HET-1A 细胞作为 GERD 中人类食管粘膜反应模型的有效性。
