title: Aspirin induces gastric epithelial barrier dysfunction by activating p38 MAPK via claudin-7.
abstract: Tight junctions create a paracellular permeability barrier that is breached when nonsteroidal anti-inflammatory drugs cause gastrointestinal injury, including increased gastrointestinal permeability. However, the mechanism by which aspirin affects the function of gastric epithelial tight junctions is unknown. Thus, we examined the effect of aspirin on gastric mucosal barrier properties and tight junction organization using MKN28, a human gastric epithelial cell line that expresses claudin-3, claudin-4, claudin-7, zonula occludens (ZO)-1, and occludin, but not claudin-2 or claudin-5, as determined by immunoblot analysis and immunofluorescent staining. Aspirin (5 mM) treatment of MKN28 gastric epithelial monolayers significantly decreased transepithelial electrical resistance and increased dextran permeability. Both aspirin-mediated permeability and phosphorylation of p38 MAPK were significantly attenuated by SB-203580 (a p38 MAPK inhibitor) but not by U-0126 (a MEK1 inhibitor) or SP-600125 (a JNK inhibitor). Aspirin significantly decreased the quantity of claudin-7 protein produced by MKN28 cells but not the quantity of claudin-3, claudin-4, ZO-1, or occludin. The aspirin-induced decrease in claudin-7 protein was completely abolished by SB-203580 pretreatment. These results demonstrate, for the first time, that claudin-7 protein is important in aspirin-induced gastric barrier loss and that p38 MAPK activity mediates this epithelial barrier dysfunction.
authors.affiliation: Department of Internal Medicine and Bioregulation, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan. t-oshima@hyo-med.ac.jp
authors.forename: Tadayuki
authors.initials: T
authors.lastname: Oshima
authors.forename: Hiroto
authors.initials: H
authors.lastname: Miwa
authors.forename: Takashi
authors.initials: T
authors.lastname: Joh
mesh_terms: D000368:Aged; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000633:toxicity*; D001241:Aspirin / Q000633:toxicity*; D002460:Cell Line; D057167:Claudins; D003911:Dextrans / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D017097:Electric Impedance; D004847:Epithelial Cells / Q000187:drug effects* / Q000201:enzymology; D005260:Female; D005753:Gastric Mucosa / Q000187:drug effects* / Q000201:enzymology; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D010539:Permeability; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013274:Stomach Neoplasms / Q000201:enzymology; D019108:Tight Junctions / Q000187:drug effects* / Q000201:enzymology; D013997:Time Factors; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; C473255:CLDN7 protein, human; D057167:Claudins; D003911:Dextrans; D008565:Membrane Proteins; D047428:Protein Kinase Inhibitors; D034741:RNA, Small Interfering; D048051:p38 Mitogen-Activated Protein Kinases; D001241:Aspirin