Ann Rheum Dis doi:10.1136/annrheumdis-2012-201958
  • Basic and translational research
  • Extended report

Toll-like receptor-mediated, enhanced production of profibrotic TIMP-1 in monocytes from patients with systemic sclerosis: role of serum factors

  1. Jacob M van Laar1
  1. 1Musculoskeletal Research Group, Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, UK
  2. 2Department of Rheumatology, University Hospital Basel, Basel, Switzerland
  3. 3Department of Rheumatology, Freeman Hospital, Newcastle upon Tyne, UK
  4. 4Department of Rheumatology and Clinical Immunology, University Medical Centre Utrecht, Utrecht, The Netherlands
  1. Correspondence to Professor Jacob M van Laar, Musculoskeletal Research Group, Institute of Cellular Medicine, Newcastle University, 4th Floor, Catherine Cookson Building, The Medical School, Framlington Place, Newcastle upon Tyne NE2 4HH, UK; j.m.van-laar{at}
  • Received 4 May 2012
  • Revised 23 October 2012
  • Accepted 18 November 2012
  • Published Online First 6 December 2012


Objectives 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.