title: Interleukin-10 regulates TNF-alpha-converting enzyme (TACE/ADAM-17) involving a TIMP-3 dependent and independent mechanism.
abstract: IL-10 is a potent anti-inflammatory molecule, which regulates TNF-alpha at multiple levels. We investigated whether IL-10 also modulated the activity of the TNF-alpha-converting enzyme (TACE). Using an ex vivo fluorogenic assay we observed that LPS rapidly induced TACE activity in monocytes coinciding with release of soluble TNF-alpha. In the presence of IL-10, TNF-alpha production and activation of surface TACE was significantly inhibited. Paradoxically, both LPS with or without IL-10 led to accumulation of surface TACE (albeit catalytically inactive) over a 24 h period. We investigated whether this was mediated through induction of endogenous tissue inhibitor metalloproteinase-3 (TIMP-3). We found that the inhibition of TACE activity at 2 h by IL-10 was not TIMP-3 dependent but that the late accumulation of surface TACE was prevented with TIMP-3 antibodies. Furthermore, induction of endogenous TIMP-3 was observed by western blotting in both LPS- and in LPS with IL-10-treated monocytes from 6 to 8 h of culture. These results indicate that IL-10 further regulates TNF-alpha by modulating TACE activation at early time points and by contributing to the induction of TIMP-3, the natural inhibitor of active TACE, at later time points. These observations add to our understanding of inflammation and the importance of homeostatic regulators of these events.
authors.affiliation: Kennedy Institute of Rheumatology Division, Faculty of Medicine, Imperial College of Science, Technology and Medicine, London, UK. f.brennan@imperial.ac.uk
authors.forename: Fionula M
authors.initials: FM
authors.lastname: Brennan
authors.forename: Patricia
authors.initials: P
authors.lastname: Green
authors.forename: Parisa
authors.initials: P
authors.lastname: Amjadi
authors.forename: Heidi J
authors.initials: HJ
authors.lastname: Robertshaw
authors.forename: Montserrat
authors.initials: M
authors.lastname: Alvarez-Iglesias
authors.forename: Masao
authors.initials: M
authors.lastname: Takata
mesh_terms: D051722:ADAM Proteins / Q000378:metabolism*; D000072198:ADAM17 Protein; D000906:Antibodies / Q000276:immunology; D002384:Catalysis; D002462:Cell Membrane / Q000187:drug effects / Q000201:enzymology; D002478:Cells, Cultured; D006801:Humans; D016753:Interleukin-10 / Q000494:pharmacology*; D008070:Lipopolysaccharides / Q000494:pharmacology; D018613:Microscopy, Confocal; D009000:Monocytes / Q000187:drug effects / Q000276:immunology / Q000378:metabolism; D012995:Solubility; D019717:Tissue Inhibitor of Metalloproteinase-3 / Q000276:immunology / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis; D015854:Up-Regulation
chemical_list: D000906:Antibodies; D008070:Lipopolysaccharides; D019717:Tissue Inhibitor of Metalloproteinase-3; D014409:Tumor Necrosis Factor-alpha; D016753:Interleukin-10; D051722:ADAM Proteins; D000072198:ADAM17 Protein; C000606462:ADAM17 protein, human