Expression of the components and regulatory proteins of the classical pathway of complement in normal and diseased synovium

Gulati, P., Guc, D., Lemercier, C., Lappin, D. and Whaley, K. (1994) Expression of the components and regulatory proteins of the classical pathway of complement in normal and diseased synovium. Rheumatology International, 14(1), pp. 13-19. (doi: 10.1007/BF00302666)

Abstract

We studied the synthesis of the classical pathway complement components in synovial membrane. Ribonucleic acid was extracted from the synovial membranes of patients with rheumatoid arthritis (RA) or osteoarthritis (OA), as well as from normal synovial membrane. Northern blot and dot blot analysis showed that the mRNAs for all classical pathway complement components (C1qA chain, C1qB chain, C1qC chain, C1r, C1s, C4 and C2) and the fluid-phase regulatory components (C1-inhibitor, C4-bp and factor I) were present in all three types of synovial membrane. Thus, all the components of the classical pathway were expressed in normal and diseased synovium. In an attempt to determine which components were synthesised by each cell type, monocytes (mononuclear phagocytes), human umbilical vein endothelial cells (HUVEC), synovial membrane fibroblasts (from normal, OA and RA synovial membrane) and peripheral blood lymphocytes were cultured in vitro and secretion rates of individual components were measured and total cellular RNA was analysed by Northern blotting. Monocytes secreted C1q, C1r, C1s, C4, C2, C1-inhibitor and C4-bp but not factor I. Fibroblasts secreted C1r, C1s, C2, C3, C1-inhibitor and factor I but not C1q, C4 or C4-bp. HUVEC secreted C1s, C2, C1-inhibitor and factor I but not C1q, C1r, C4 or C4-bp. Lymphocytes did not secrete any of these components. In three instances mRNA was detected in the absence of secreted protein: mRNAs for the C1qA and C1qC chains were detected in HUVEC, whereas the mRNA for the C1qB chain was not, and C4 mRNA was detected in both fibroblasts and HUVEC. In the former the hybridisation signal was strong, whereas in the latter it was weak. These data indicated that, at least in fibroblasts, there may be a block in C4 translation. The results of these studies suggested that all of the classical pathway components are synthesised in normal, RA and OA synovial membrane, and this may be explained at least in part by synthesis in mononuclear phagocytes, endothelial cells and fibroblasts. They also showed that there are important cellspecific differences in the expression of the genes for the proteins of the classical complement pathway that require further investigation.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Lappin, Dr David
• Authors: Gulati, P., Guc, D., Lemercier, C., Lappin, D., and Whaley, K.
• Subjects: Q Science > QR Microbiology > QR180 Immunology
• College/School: College of Medical Veterinary and Life Sciences > School of Medicine, Dentistry & Nursing > Dental School
• Journal Name: Rheumatology International
• ISSN: 0172-8172
• ISSN (Online): 1437-160X