title: TACE inhibition amplifies TNF-alpha-mediated colonic epithelial barrier disruption.
abstract: Inflammatory bowel diseases (IBD) are characterized by tumor necrosis factor alpha (TNF-alpha)-mediated epithelial barrier disruption. TNF-alpha production and the bioavailability of its receptors on the cell surface are regulated by TACE (TNF-alpha converting enzyme), a pleiotropic metalloprotease also known as ADAM17, and its specific inhibitor TIMP3. We therefore examined ADAM17 and TIMP3 expression in human intestinal epithelial cells (IEC) using immunohistochemistry on tissue microarrays and real-time PCR on preparations of IEC isolated from human normal and IBD colon. The effects of TACE inhibition by TIMP3 or a pharmacological inhibitor were assessed in inflammatory conditions on a TIMP3-deficient colonic cell line HT29-Cl.16E. Both TACE and TIMP3 were found to be constitutively expressed by intestinal epithelial cells in the normal and inflammatory human intestinal barrier. In the TIMP3-deficient cell line, the addition of recombinant human TIMP3 or of Tapi-2, a pharmacological ADAM17 inhibitor, i) sensitized the cells to TNF-alpha-mediated hyperpermeability, ii) down-regulated tight junction-associated protein expression and iii) inhibited TNFRI shedding. In conclusion, our data showed that TACE and TIMP3 were co-expressed in the human intestinal barrier and that TACE inhibition, either physiologically or pharmacologically, amplified TNF-alpha-mediated hyperpermeability. TIMP3 could thus play a major role in inflammatory conditions by creating an autocrine effect leading to amplified epithelial barrier hyperpermeability.
authors.affiliation: INSERM U539, Faculté de Médecine, F-44035 Nantes, France.
authors.forename: Thomas
authors.initials: T
authors.lastname: Fréour
authors.forename: Anne
authors.initials: A
authors.lastname: Jarry
authors.forename: Kalyane
authors.initials: K
authors.lastname: Bach-Ngohou
authors.forename: Thomas
authors.initials: T
authors.lastname: Dejoie
authors.forename: Chantal
authors.initials: C
authors.lastname: Bou-Hanna
authors.forename: Marc G
authors.initials: MG
authors.lastname: Denis
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Mosnier
authors.forename: Christian L
authors.initials: CL
authors.lastname: Laboisse
authors.forename: Damien
authors.initials: D
authors.lastname: Masson
mesh_terms: D051722:ADAM Proteins / Q000235:genetics / Q000276:immunology*; D000072198:ADAM17 Protein; D000328:Adult; D000368:Aged; D045744:Cell Line, Tumor; D003106:Colon / Q000166:cytology / Q000201:enzymology / Q000276:immunology; D004847:Epithelial Cells / Q000166:cytology / Q000201:enzymology / Q000276:immunology; D005260:Female; D005786:Gene Expression Regulation; D006801:Humans; D015212:Inflammatory Bowel Diseases / Q000201:enzymology / Q000235:genetics / Q000276:immunology*; D007413:Intestinal Mucosa / Q000166:cytology / Q000201:enzymology / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D047888:Receptors, Tumor Necrosis Factor, Type I / Q000378:metabolism; D019717:Tissue Inhibitor of Metalloproteinase-3 / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000276:immunology*; D055815:Young Adult
chemical_list: D047888:Receptors, Tumor Necrosis Factor, Type I; C088390:TIMP3 protein, human; D019717:Tissue Inhibitor of Metalloproteinase-3; D014409:Tumor Necrosis Factor-alpha; D051722:ADAM Proteins; D000072198:ADAM17 Protein; C000606462:ADAM17 protein, human