EXTENDED REPORT

Expression and localisation of the new metalloproteinase inhibitor RECK (reversion inducing cysteine-rich protein with Kazal motifs) in inflamed synovial membranes of patients with rheumatoid arthritis

P L E M van Lent¹, P N Span², A W Sloetjes¹, T R D J Radstake¹, A W T van Lieshout¹, J J T M Heuvel², C G J Sweep², W B van den Berg¹

¹ Department of Rheumatology, University Medical Centre Nijmegen, Nijmegen, The Netherlands
² Department of Chemical Endocrinology, University Medical Centre Nijmegen, Nijmegen, The Netherlands

Correspondence to:
Dr P L E M van Lent
Department of Rheumatology, University Medical Centre Nijmegen, Geert Grooteplein 26–28, 6500 HB Nijmegen, The Netherlands; P.vanlent{at}reuma.umcn.nl

Objective: To assess the expression and localisation of the new metalloproteinase inhibitor RECK, an inhibitor of matrix metalloproteinase-14 (MMP-14) secretion and activity, in the synovial membrane of patients with rheumatoid arthritis (RA).

Methods: RECK expression in synovium samples from patients with RA, osteoarthritis (OA), and "trauma" were studied by quantitative real time reverse transcription-polymerase chain reaction (Q-PCR). RECK mRNA levels were compared with those of the enzyme MMP-14. RECK expression on cryostat sections of synovium was disclosed by goat-antihuman RECK monoclonal antibody. RECK protein was detected on synovial cryostat sections and measured by western blotting. RECK expression on macrophages was investigated by double staining of CD68 and RECK on cryostat sections and characterised by confocal microscopy. RECK expression on RA monocytes or normal monocytes was further investigated by FACS analysis.

Results: RECK expression in the synovial membrane of patients with RA was significantly lower than in OA and controls. MMP-14 mRNA levels were not significantly different between the three groups. In RA synovium, RECK protein was expressed mainly in the lining layer but also by macrophages around blood vessels. Fibroblasts and about 50% of the CD68 positive macrophages expressed RECK. In CD68 positive macrophages, RECK was only expressed in secretory granules and not on the membrane. The same pattern was found in M-CSF cultured macrophages of patients with RA and controls. In contrast, synovial fibroblasts showed a diffuse membrane expression within the synovium similar to cultured RA fibroblasts. RECK expression was low on the membrane of monocytes according to FACS analysis.

Conclusion: The new MMP inhibitor RECK is expressed in synovial membranes of RA, OA, and controls. RECK mRNA is lowest in RA synovial membranes. In contrast with fibroblasts, macrophages in the synovium express RECK only cytoplasmically and not on their membrane.

Abbreviations: DMEM, Dulbecco’s modified Eagle’s medium; ECM, extracellular matrix; M-CSF, monocyte-colony stimulating factor; MMPs, matrix metalloproteinases; MT-MMPs, membrane bound MMPs; OA, osteoarthritis; Q-PCR, quantitative real time reverse transcription-polymerase chain reaction; RA, rheumatoid arthritis; RECK, reversion inducing cysteine-rich protein with Kazal motifs

Keywords: matrix metalloproteinase inhibitors; RECK; rheumatoid arthritis; synovial membrane

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

• Miki, T., Takegami, Y., Okawa, K., Muraguchi, T., Noda, M., Takahashi, C. (2007). The Reversion-inducing Cysteine-rich Protein with Kazal Motifs (RECK) Interacts with Membrane Type 1 Matrix Metalloproteinase and CD13/Aminopeptidase N and Modulates Their Endocytic Pathways. J. Biol. Chem. 282: 12341-12352 [Abstract] [Full Text]  
• Kondo, S., Shukunami, C., Morioka, Y., Matsumoto, N., Takahashi, R., Oh, J., Atsumi, T., Umezawa, A., Kudo, A., Kitayama, H., Hiraki, Y., Noda, M. (2007). Dual effects of the membrane-anchored MMP regulator RECK on chondrogenic differentiation of ATDC5 cells. J. Cell Sci. 120: 849-857 [Abstract] [Full Text]