title: Adalimumab prevents barrier dysfunction and antagonizes distinct effects of TNF-α on tight junction proteins and signaling pathways in intestinal epithelial cells.
abstract: Intestinal barrier dysfunction is pivotal in the etiology of inflammatory bowel diseases. Combined clinical and endoscopic remission ("mucosal healing") in patients who received anti-TNF-α therapies suggests restitution of the intestinal barrier, but the mechanisms involved are largely unknown. We therefore investigated the impact of the anti-TNF-α antibody adalimumab on barrier function in two in vitro models. Combined stimulation of Caco-2 and T-84 cells with interferon-γ and TNF-α resulted in a significant decrease of transepithelial electrical resistance (TEER) within 6 h that was prevented by adalimumab in concentrations down to 100 ng/ml. Adalimumab furthermore antagonized the appearance of irregular membrane undulations and prevented internalization of tight junction proteins upon cytokine exposure. In addition, TNF-α induced a downregulation of claudin-1, claudin-2, claudin-4, and occludin as well as activation of phosphatidylinositol 3-kinase signaling in T-84 but not Caco-2 cells, which was reversed by adalimumab. At the signaling level, adalimumab prevented increased phosphorylation of myosin light chain as well as activation of p38 MAPK and NF-κB accompanying the decline in TEER in both model systems. Pharmacological inhibition of NF-κB signaling partially prevented the TNF-α-induced TEER loss, whereas inhibition of p38 worsened barrier dysfunction in Caco-2 but not T-84 cells. Taken together, these data demonstrate that adalimumab prevents barrier dysfunction induced by TNF-α both functionally and structurally as well as at the level of signal transduction. Barrier protection might therefore constitute a novel mechanism how anti-TNF-α therapy contributes to epithelial restitution and tissue repair in inflammatory bowel diseases.
authors.affiliation: Department of Medicine, Division of Gastroenterology and Hepatology, Humboldt-University of Berlin, Berlin, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Fischer
authors.forename: Markus
authors.initials: M
authors.lastname: Gluth
authors.forename: Ulrich-Frank
authors.initials: UF
authors.lastname: Pape
authors.forename: Bertram
authors.initials: B
authors.lastname: Wiedenmann
authors.forename: Franz
authors.initials: F
authors.lastname: Theuring
authors.forename: Daniel C
authors.initials: DC
authors.lastname: Baumgart
mesh_terms: D000068879:Adalimumab; D000893:Anti-Inflammatory Agents / Q000494:pharmacology*; D061067:Antibodies, Monoclonal, Humanized / Q000494:pharmacology*; D018938:Caco-2 Cells; D016207:Cytokines / Q000378:metabolism; D017097:Electric Impedance; D006801:Humans; D007371:Interferon-gamma / Q000378:metabolism; D007413:Intestinal Mucosa / Q000187:drug effects* / Q000378:metabolism; D009218:Myosins / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D010539:Permeability / Q000187:drug effects; D058539:Phosphatidylinositol 3-Kinase / Q000378:metabolism; D010766:Phosphorylation; D015398:Signal Transduction / Q000187:drug effects*; D062725:Tight Junction Proteins / Q000378:metabolism*; D019108:Tight Junctions / Q000187:drug effects / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D000893:Anti-Inflammatory Agents; D061067:Antibodies, Monoclonal, Humanized; D016207:Cytokines; D016328:NF-kappa B; D062725:Tight Junction Proteins; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma; D058539:Phosphatidylinositol 3-Kinase; D048051:p38 Mitogen-Activated Protein Kinases; D009218:Myosins; D000068879:Adalimumab
keywords: Crohn's disease; IBD; claudin; intestinal barrier; tumor necrosis factor-α; ulcerative colitis