title: Metalloproteinase-dependent TLR2 ectodomain shedding is involved in soluble toll-like receptor 2 (sTLR2) production.
abstract: Toll-like receptor (TLR) 2, a type I membrane receptor that plays a key role in innate immunity, recognizes conserved molecules in pathogens, and triggering an inflammatory response. It has been associated with inflammatory and autoimmune diseases. Soluble TLR2 (sTLR2) variants have been identified in human body fluids, and the TLR2 ectodomain can negatively regulate TLR2 activation by behaving as a decoy receptor. sTLR2 generation does not involve alternative splicing mechanisms, indicating that this process might involve a post-translational modification of the full-length receptor; however, the specific mechanism has not been studied. Using CD14+ peripheral human monocytes and the THP-1 monocytic leukemia-derived cell line, we confirm that sTLR2 generation increases upon treatment with pro-inflammatory agents and requires a post-translational mechanism. We also find that the constitutive and ligand-induced release of sTLR2 is sensitive to pharmacological metalloproteinase activator and inhibitors leading us to conclude that metalloproteinase TLR2 shedding contributes to soluble receptor production. By expressing human TLR2 in ADAM10- or ADAM17-deficient MEF cells, we find both enzymes to be implicated in TLR2 ectodomain shedding. Moreover, using a deletion mutant of the TLR2 juxtamembrane region, we demonstrate that this domain is required for sTLR2 generation. Functional analysis suggests that sTLR2 generated by metalloproteinase activation inhibitsTLR2-induced cytokine production by this monocytic leukemia-derived cell line. The identification of the mechanisms involved in regulating the availability of soluble TLR2 ectodomain and cell surface receptors may contribute further research on TLR2-mediated processes in innate immunity and inflammatory disorders.
authors.affiliation: Disciplinary Program of Immunology, Institute of Biomedical Sciences, Faculty of Medicine, Universidad de Chile, Santiago, Chile.
authors.forename: Patricia
authors.initials: P
authors.lastname: Langjahr
authors.affiliation: Disciplinary Program of Immunology, Institute of Biomedical Sciences, Faculty of Medicine, Universidad de Chile, Santiago, Chile.
authors.forename: David
authors.initials: D
authors.lastname: Díaz-Jiménez
authors.affiliation: Disciplinary Program of Immunology, Institute of Biomedical Sciences, Faculty of Medicine, Universidad de Chile, Santiago, Chile.
authors.forename: Marjorie
authors.initials: M
authors.lastname: De la Fuente
authors.affiliation: Disciplinary Program of Immunology, Institute of Biomedical Sciences, Faculty of Medicine, Universidad de Chile, Santiago, Chile.
authors.forename: Estefhany
authors.initials: E
authors.lastname: Rubio
authors.affiliation: Division of Infectious Diseases & Immunology, University of Massachusetts Medical School, Worcester, MA, United States of America.
authors.forename: Douglas
authors.initials: D
authors.lastname: Golenbock
authors.affiliation: Physiology Department, Millennium Nucleus in Regenerative Biology (MINREB), Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile.
authors.forename: Francisca C
authors.initials: FC
authors.lastname: Bronfman
authors.affiliation: Gastroenterology Unit, Clínica Las Condes, Santiago, Chile.
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Quera
authors.affiliation: Cell and Molecular Biology Program, Biomedical Sciences Institute, Faculty of Medicine, Universidad de Chile, Santiago, Chile.
authors.forename: María-Julieta
authors.initials: MJ
authors.lastname: González
authors.affiliation: Disciplinary Program of Immunology, Institute of Biomedical Sciences, Faculty of Medicine, Universidad de Chile, Santiago, Chile.
authors.forename: Marcela A
authors.initials: MA
authors.lastname: Hermoso
mesh_terms: D051722:ADAM Proteins / Q000378:metabolism; D000072197:ADAM10 Protein; D000072198:ADAM17 Protein; D000595:Amino Acid Sequence; D053829:Amyloid Precursor Protein Secretases / Q000378:metabolism; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D016209:Interleukin-8 / Q000096:biosynthesis; D008024:Ligands; D055666:Lipopeptides / Q000494:pharmacology; D008565:Membrane Proteins / Q000378:metabolism; D045726:Metalloproteases / Q000378:metabolism*; D008969:Molecular Sequence Data; D009000:Monocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D017434:Protein Structure, Tertiary; D012995:Solubility; D051195:Toll-Like Receptor 2 / Q000096:biosynthesis* / Q000737:chemistry* / Q000378:metabolism
chemical_list: D016209:Interleukin-8; D008024:Ligands; D055666:Lipopeptides; D008565:Membrane Proteins; C508075:Pam(3)CSK(4) peptide; D051195:Toll-Like Receptor 2; D053829:Amyloid Precursor Protein Secretases; D045726:Metalloproteases; D051722:ADAM Proteins; D000072197:ADAM10 Protein; C491236:ADAM10 protein, human; D000072198:ADAM17 Protein; C000606462:ADAM17 protein, human