Liping Wu1,2, Tadayuki Oshima3, Toshihiko Tomita1, Yoshio Ohda1, Hirokazu Fukui1, Jiro Watari1, Hiroto Miwa1. 1. Division of Gastroenterology, Department of Internal Medicine, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, Hyogo, 663-8501, Japan. 2. Department of Gastroenterology, The Third People's Hospital of Chengdu, Chengdu, China. 3. Division of Gastroenterology, Department of Internal Medicine, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, Hyogo, 663-8501, Japan. t-oshima@hyo-med.ac.jp.
Abstract
BACKGROUND: Serotonin regulates gastrointestinal function, and mast cells are a potential nonneuronal source of serotonin in the esophagus. Tight junction (TJ) proteins in the esophageal epithelium contribute to the barrier function, and the serotonin signaling pathway may contribute to epithelial leakage in gastroesophageal reflux disease. Therefore, the aim of this study was to investigate the role of serotonin on barrier function, TJ proteins, and related signaling pathways. METHODS: Normal primary human esophageal epithelial cells were cultured with use of an air-liquid interface system. Serotonin was added to the basolateral compartment, and transepithelial electrical resistance (TEER) was measured. The expression of TJ proteins and serotonin receptor 7 (5-HT7) was assessed by Western blotting. The involvement of 5-HT7 was assessed with use of an antagonist and an agonist. The underlying cellular signaling pathways were examined with use of specific blockers. RESULTS: Serotonin decreased TEER and reduced the expression of TJ proteins ZO-1, occludin, and claudin 1, but not claudin 4. A 5-HT7 antagonist blocked the serotonin-induced decrease in TEER, and a 5-HT7 agonist decreased TEER. Inhibition of p38 mitogen-activated protein kinase (MAPK) reduced the serotonin-induced decrease in TEER. Inhibition of p38 MAPK blocked the decrease of ZO-1 levels, whereas extracellular-signal-regulated kinase (ERK) inhibition blocked the decrease in occludin levels. Cell signaling pathway inhibitors had no effect on serotonin-induced alterations in claudin 1 and claudin 4 levels. Serotonin induced phosphorylation of p38 MAPK and ERK, and a 5-HT7 antagonist partially blocked serotonin-induced phosphorylation of p38 MAPK but not that of ERK. CONCLUSIONS: Serotonin disrupted esophageal squamous epithelial barrier function by modulating the levels of TJ proteins. Serotonin signaling pathways may mediate the pathogenesis of gastroesophageal reflux disease.
BACKGROUND:Serotonin regulates gastrointestinal function, and mast cells are a potential nonneuronal source of serotonin in the esophagus. Tight junction (TJ) proteins in the esophageal epithelium contribute to the barrier function, and the serotonin signaling pathway may contribute to epithelial leakage in gastroesophageal reflux disease. Therefore, the aim of this study was to investigate the role of serotonin on barrier function, TJ proteins, and related signaling pathways. METHODS: Normal primary human esophageal epithelial cells were cultured with use of an air-liquid interface system. Serotonin was added to the basolateral compartment, and transepithelial electrical resistance (TEER) was measured. The expression of TJ proteins and serotonin receptor 7 (5-HT7) was assessed by Western blotting. The involvement of 5-HT7 was assessed with use of an antagonist and an agonist. The underlying cellular signaling pathways were examined with use of specific blockers. RESULTS:Serotonin decreased TEER and reduced the expression of TJ proteins ZO-1, occludin, and claudin 1, but not claudin 4. A 5-HT7 antagonist blocked the serotonin-induced decrease in TEER, and a 5-HT7 agonist decreased TEER. Inhibition of p38 mitogen-activated protein kinase (MAPK) reduced the serotonin-induced decrease in TEER. Inhibition of p38 MAPK blocked the decrease of ZO-1 levels, whereas extracellular-signal-regulated kinase (ERK) inhibition blocked the decrease in occludin levels. Cell signaling pathway inhibitors had no effect on serotonin-induced alterations in claudin 1 and claudin 4 levels. Serotonin induced phosphorylation of p38 MAPK and ERK, and a 5-HT7 antagonist partially blocked serotonin-induced phosphorylation of p38 MAPK but not that of ERK. CONCLUSIONS:Serotonin disrupted esophageal squamous epithelial barrier function by modulating the levels of TJ proteins. Serotonin signaling pathways may mediate the pathogenesis of gastroesophageal reflux disease.
Authors: P Koutsoumbi; E Epanomeritakis; J Tsiaoussis; H Athanasakis; E Chrysos; O Zoras; J S Vassilakis; E Xynos Journal: Am J Gastroenterol Date: 2000-12 Impact factor: 10.864
Authors: T Piche; G Barbara; P Aubert; S Bruley des Varannes; R Dainese; J L Nano; C Cremon; V Stanghellini; R De Giorgio; J P Galmiche; M Neunlist Journal: Gut Date: 2008-09-29 Impact factor: 23.059