title: Toll-like receptor-mediated, enhanced production of profibrotic TIMP-1 in monocytes from patients with systemic sclerosis: role of serum factors.
abstract: OBJECTIVE
  To investigate whether monocytes contribute to matrix deposition in systemic sclerosis (SSc) by production of tissue-inhibitor of metalloproteinase-1 (TIMP-1).
  
  
  METHODS
  Matrix metalloproteinase-1 (MMP-1) and TIMP-1 expression and secretion were measured by qRT-PCR and ELISA in circulating monocytes from patients with SSc, patients with rheumatoid arthritis (RA) and healthy controls (HC) and in healthy monocytes cultured in the presence of SSc or HC serum samples. Production of TIMP-1 was determined in response to a panel of Toll-like receptor (TLR) agonists and MyD88 inhibitory peptide. The functional effect of conditioned media from SSc and HC serum samples or TLR8-stimulated monocytes was studied in an MMP-1 activity assay.
  
  
  RESULTS
  TIMP-1 production by monocytes was upregulated in patients with SSc compared with patients with RA and HC. Incubation of HC monocytes with SSc serum samples resulted in functionally active TIMP-1 production. However, pretreatment with MyD88 inhibitor, but not control peptide, decreased TIMP-1 secretion. TIMP-1 production was significantly stronger when SSc and HC monocytes were stimulated with TLR8 (ssRNA) agonist, but the response was more pronounced in SSc monocytes. TIMP-1 production after TLR stimulation was also strongly reduced in the presence of MyD88 inhibitory peptide or in the monocytes isolated from a patient with a genetic TLR signalling defect. MMP-1 activity was significantly inhibited in media from serum samples or TLR8-stimulated monocytes indicative of functional TIMP activity.
  
  
  CONCLUSIONS
  This study demonstrates profibrotic properties of circulating monocytes from patients with SSc and a key role for TLR signalling, particularly TLR8, in TIMP-1 secretion and matrix remodelling.
authors.affiliation: Musculoskeletal Research Group, Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, UK.
authors.forename: Marzena
authors.initials: M
authors.lastname: Ciechomska
authors.forename: Christiaan A
authors.initials: CA
authors.lastname: Huigens
authors.forename: Thomas
authors.initials: T
authors.lastname: Hügle
authors.forename: Tess
authors.initials: T
authors.lastname: Stanly
authors.forename: Andreas
authors.initials: A
authors.lastname: Gessner
authors.forename: Bridget
authors.initials: B
authors.lastname: Griffiths
authors.forename: Timothy R D J
authors.initials: TR
authors.lastname: Radstake
authors.forename: Sophie
authors.initials: S
authors.lastname: Hambleton
authors.forename: Steven
authors.initials: S
authors.lastname: O'Reilly
authors.forename: Jacob M
authors.initials: JM
authors.lastname: van Laar
mesh_terms: D001172:Arthritis, Rheumatoid / Q000097:blood / Q000235:genetics; D017077:Culture Media, Conditioned / Q000494:pharmacology; D005355:Fibrosis / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D006801:Humans; D018950:Lipopolysaccharide Receptors / Q000378:metabolism; D020781:Matrix Metalloproteinase 1 / Q000235:genetics / Q000378:metabolism*; D009000:Monocytes / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D053594:Myeloid Differentiation Factor 88 / Q000378:metabolism; D012595:Scleroderma, Systemic / Q000097:blood* / Q000235:genetics; D012867:Skin / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000096:biosynthesis* / Q000235:genetics; D051200:Toll-Like Receptor 8 / Q000819:agonists / Q000378:metabolism*; D015854:Up-Regulation
chemical_list: D017077:Culture Media, Conditioned; D018950:Lipopolysaccharide Receptors; C507779:MYD88 protein, human; D053594:Myeloid Differentiation Factor 88; C560822:TIMP1 protein, human; C495349:TLR8 protein, human; D019715:Tissue Inhibitor of Metalloproteinase-1; D051200:Toll-Like Receptor 8; D020781:Matrix Metalloproteinase 1