title: High-mobility group box 1 impairs airway epithelial barrier function through the activation of the RAGE/ERK pathway.
abstract: Recent studies have indicated that high-mobility group box 1 protein (HMGB1) and the receptor for advanced glycation end-products (RAGE) contribute to the pathogenesis of asthma. However, whether the activation of the HMGB1/RAGE axis mediates airway epithelial barrier dysfunction remains unknown. Thus, the aim of this study was to examine the effects of HMGB1 and its synergistic action with interleukin (IL)-1β on airway epithelial barrier properties. We evaluated the effects of recombinant human HMGB1 alone or in combination with IL-1β on ionic and macromolecular barrier permeability, by culturing air-liquid interface 16HBE cells with HMGB1 to mimic the differentiated epithelium. Western blot analysis and immunofluorescence staining were utilized to examine the level and structure of major junction proteins, namely E-cadherin, β-catenin, occludin and claudin-1. Furthermore, we examined the effects of RAGE neutralizing antibodies and mitogen-activated protein kinase (MAPK) inhibitors on epithelial barrier properties in order to elucidate the mechanisms involved. HMGB1 increased FITC-dextran permeability, but suppressed epithelial resistance in a dose- and time-dependent manner. HMGB1-mediated barrier hyperpermeability was accompanied by a disruption of cell-cell contacts, the selective downregulation of occludin and claudin-1, and the redistribution of E-cadherin and β-catenin. HMGB1 in synergy with IL-1β induced a similar, but greater barrier hyperpermeability and induced the disruption of junction proteins. Furthermore, HMGB1 elicited the activation of the RAGE/extracellular signal-related kinase (ERK)1/2 signaling pathway, which correlated with barrier dysfunction in the 16HBE cells. Anti-RAGE antibody and the ERK1/2 inhibitor, U0126, attenuated the HMGB1-mediated changes in barrier permeability, restored the expression levels of occludin and claudin-1 and pevented the redistribution of E-cadherin and β-catenin. Taken together, the findings of our study demonstrate that HMGB1 is capable of inducing potent effects on epithelial barrier function and that RAGE/ERK1/2 is a key signaling pathway involved in the crosstalk between formations of junction proteins and epithelial barrier dysfunction.
authors.affiliation: Chronic Airways Diseases Laboratory, Department of Respiratory and Critical Care Medicine, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong 510515, P.R. China.
authors.forename: Wufeng
authors.initials: W
authors.lastname: Huang
authors.affiliation: Chronic Airways Diseases Laboratory, Department of Respiratory and Critical Care Medicine, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong 510515, P.R. China.
authors.forename: Haijin
authors.initials: H
authors.lastname: Zhao
authors.affiliation: Chronic Airways Diseases Laboratory, Department of Respiratory and Critical Care Medicine, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong 510515, P.R. China.
authors.forename: Hangming
authors.initials: H
authors.lastname: Dong
authors.affiliation: Chronic Airways Diseases Laboratory, Department of Respiratory and Critical Care Medicine, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong 510515, P.R. China.
authors.forename: Yue
authors.initials: Y
authors.lastname: Wu
authors.affiliation: Chronic Airways Diseases Laboratory, Department of Respiratory and Critical Care Medicine, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong 510515, P.R. China.
authors.forename: Lihong
authors.initials: L
authors.lastname: Yao
authors.affiliation: School of Public Health and Tropical Medicine, Southern Medical University, Guangzhou, Guangdong 510515, P.R. China.
authors.forename: Fei
authors.initials: F
authors.lastname: Zou
authors.affiliation: Chronic Airways Diseases Laboratory, Department of Respiratory and Critical Care Medicine, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong 510515, P.R. China.
authors.forename: Shaoxi
authors.initials: S
authors.lastname: Cai
mesh_terms: D002460:Cell Line; D004847:Epithelial Cells / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D024243:HMGB1 Protein / Q000378:metabolism*; D006801:Humans; D007365:Intercellular Junctions / Q000378:metabolism; D053583:Interleukin-1beta / Q000378:metabolism; D007477:Ions / Q000378:metabolism; D046911:Macromolecular Substances / Q000378:metabolism; D010539:Permeability; D000067759:Receptor for Advanced Glycation End Products / Q000378:metabolism*; D020545:Respiratory Mucosa / Q000378:metabolism* / Q000473:pathology; D015398:Signal Transduction
chemical_list: D024243:HMGB1 Protein; D053583:Interleukin-1beta; D007477:Ions; D046911:Macromolecular Substances; D000067759:Receptor for Advanced Glycation End Products; D048049:Extracellular Signal-Regulated MAP Kinases