title: The Anti-inflammatory Protein TSG-6 Regulates Chemokine Function by Inhibiting Chemokine/Glycosaminoglycan Interactions.
abstract: TNF-stimulated gene-6 (TSG-6) is a multifunctional protein secreted in response to pro-inflammatory stimuli by a wide range of cells, including neutrophils, monocytes, and endothelial cells. It has been shown to mediate anti-inflammatory and protective effects when administered in disease models, in part, by reducing neutrophil infiltration. Human TSG-6 inhibits neutrophil migration by binding CXCL8 through its Link module (Link_TSG6) and interfering with the presentation of CXCL8 on cell-surface glycosaminoglycans (GAGs), an interaction that is vital for the function of many chemokines. TSG-6 was also found to interact with chemokines CXCL11 and CCL5, suggesting the possibility that it may function as a broad specificity chemokine-binding protein, functionally similar to those encoded by viruses. This study was therefore undertaken to explore the ability of TSG-6 to regulate the function of other chemokines. Herein, we demonstrate that Link_TSG6 binds chemokines from both the CXC and CC families, including CXCL4, CXCL12, CCL2, CCL5, CCL7, CCL19, CCL21, and CCL27. We also show that the Link_TSG6-binding sites on chemokines overlap with chemokine GAG-binding sites, and that the affinities of Link_TSG6 for these chemokines (KD values 1-85 nm) broadly correlate with chemokine-GAG affinities. Link_TSG6 also inhibits chemokine presentation on endothelial cells not only through a direct interaction with chemokines but also by binding and therefore masking the availability of GAGs. Along with previous work, these findings suggest that TSG-6 functions as a pluripotent regulator of chemokines by modulating chemokine/GAG interactions, which may be a major mechanism by which TSG-6 produces its anti-inflammatory effects in vivo.
authors.affiliation: Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, California 92093-0684; Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8TA, Scotland, United Kingdom.
authors.forename: Douglas P
authors.initials: DP
authors.lastname: Dyer
authors.affiliation: Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, California 92093-0684.
authors.forename: Catherina L
authors.initials: CL
authors.lastname: Salanga
authors.affiliation: Medical and Research Sections, Veterans Affairs San Diego Healthcare System, La Jolla, California 92093; Department of Medicine, Division of Pulmonary and Critical Care, University of California, San Diego, La Jolla, California 92093.
authors.forename: Scott C
authors.initials: SC
authors.lastname: Johns
authors.affiliation: Wellcome Trust Centre for Cell-Matrix Research, University of Manchester, Manchester M13 9PT, United Kingdom; Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, United Kingdom.
authors.forename: Elena
authors.initials: E
authors.lastname: Valdambrini
authors.affiliation: Medical and Research Sections, Veterans Affairs San Diego Healthcare System, La Jolla, California 92093; Department of Medicine, Division of Pulmonary and Critical Care, University of California, San Diego, La Jolla, California 92093.
authors.forename: Mark M
authors.initials: MM
authors.lastname: Fuster
authors.affiliation: Wellcome Trust Centre for Cell-Matrix Research, University of Manchester, Manchester M13 9PT, United Kingdom. Electronic address: caroline.milner@manchester.ac.uk.
authors.forename: Caroline M
authors.initials: CM
authors.lastname: Milner
authors.affiliation: Wellcome Trust Centre for Cell-Matrix Research, University of Manchester, Manchester M13 9PT, United Kingdom; Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, United Kingdom. Electronic address: anthony.day@manchester.ac.uk.
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Day
authors.affiliation: Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, California 92093-0684. Electronic address: thandel@ucsd.edu.
authors.forename: Tracy M
authors.initials: TM
authors.lastname: Handel
mesh_terms: D000818:Animals; D001665:Binding Sites; D002448:Cell Adhesion; D015815:Cell Adhesion Molecules / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D002465:Cell Movement; D002478:Cells, Cultured; D018925:Chemokines / Q000378:metabolism*; D042783:Endothelial Cells / Q000166:cytology / Q000378:metabolism*; D006025:Glycosaminoglycans / Q000378:metabolism*; D006493:Heparin / Q000378:metabolism; D006801:Humans; D008958:Models, Molecular; D009154:Mutation; D011485:Protein Binding; D020349:Surface Plasmon Resonance
chemical_list: D015815:Cell Adhesion Molecules; D018925:Chemokines; D006025:Glycosaminoglycans; C072273:TNFAIP6 protein, human; D006493:Heparin
keywords: TNF-stimulated gene 6 (TSG-6); cell migration; chemokine; chemokine-binding protein; glycosaminoglycan; heparan sulfate; heparin-binding protein; surface plasmon resonance (SPR)