Tracey Weiler1 , Qiujiang Du1 , Oleg Krokhin1 , Werner Ens2 , Ken Standing2 , Hani El-Gabalawy1,3 and John A Wilkins1,3
1 Department of Internal Medicine and Manitoba Centre for Proteomics and Systems Biology, University of Manitoba, Room 799, John Buhler Research Centre, 715 McDermot Avenue, Winnipeg, Manitoba, R3E 3P4, Canada
2 Department of Physics and Astronomy, University of Manitoba, 510 Allen Building, Winnipeg, Manitoba, R3T 2N2, Canada
3 Section of Rheumatology, Department of Internal Medicine, Faculty of Medicine, University of Manitoba, RR149 Rehab Hospital, 800 Sherbrook Street, Winnipeg, Manitoba, R3A 1M4, Canada
Arthritis Research & Therapy 2007, 9:R30
Joint inflammation and destruction have been linked to the deregulation of the highly synthetic fibroblast-like synoviocytes (FLSs), and much of our current understanding of the mechanisms that underlie synovitis has been collected from studies of FLSs. During a proteomic analysis of FLS cells, we identified a novel protein, c19orf10 (chromosome 19 open reading frame 10), that was produced in significant amounts by these cells. The present study provides a partial characterization of c19orf10 in FLSs, synovial fluid, and the synovium. Murine monoclonal and chicken polyclonal antibodies were produced against recombinant human c19orf10 protein and used to examine the distribution of c19orf10 in cultured FLSs and in synovial tissue sections from patients with rheumatoid arthritis or osteoarthritis. The intracellular staining pattern of c19orf10 is consistent with localization in the endoplasmic reticulum/Golgi distribution. Sections of rheumatoid arthritis and osteoarthritis synovia expressed similar patterns of c19orf10 distribution with perivascular and synovial lining staining. Double-staining in situ analysis suggests that fibroblast-like synovial cells produced c19orf10, whereas macrophages, B cells, or T cells produced little or none of this protein. There is evidence of secretion into the vascular space and the extracellular matrix surrounding the synovial lining. A competitive enzyme-linked immunosorbent assay confirmed the presence of microgram levels of c19orf10 in the synovial fluids of patients with one of various arthropathies. Collectively, these results suggest that c19orf10 is an FLS-derived protein that is secreted into the synovial fluid. However, the significance of this protein in synovial biology remains to be determined. The absence of known structural motifs or domains and its relatively late evolutionary appearance raise interesting questions about its function.
*Note: Custom IgY antibodies used in this publication were produced by Gallus Immunotech Inc. Please visit our Custom IgY production page for more information.