Expression of the components and regulatory proteins of the alternative complement pathway and the membrane attack complex in normal and diseased synovium

Abstract

We have studied synthesis of the complement components and regulatory proteins of the alternative pathway and the membrane attack complex in synovial membrane. RNA was extracted from synovial tissue of patients with rheumatoid arthritis (RA) or osteoarthritis (OA) as well as from normal synovial membrane. Dot blot analysis showed the presence of mRNAs for all the complement components and regulatory proteins (C3, factor B, factor D, C5, C6, C7, C9, factor H, factor I, S-protein, SP-40, 40, DAF, MCP, CR1, CD59), except for properdin, C8 alpha, C8 beta and C8 gamma in all three types of synovial membrane studied. 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 analysed by northern blotting. Monocytes secreted properdin, C3, and factor H but not factor B, factor I, C5, C6, C7, C8 or C9. Fibroblasts and endothelial cells secreted factor B, factor H and factor I, but not properdin, C5, C6, C7, C8 or C9. Lymphocytes did not secrete any of these components. mRNAs encoding C3, factor B, factor H, S-protein, SP-40, 40, MCP and DAF were detected in all three other cell types (monocytes, fibroblasts and HU-VEC), but factor I and CD59 mRNAs were not detected in monocytes. C5, C6, C7, C8 alpha, C8 beta, CD8 gamma and C9 mRNAs were not detected in any of the cell types studied.(ABSTRACT TRUNCATED AT 250 WORDS)

Pentoxifylline attenuates nociceptive sensitization and cytokine expression in a tibia fracture rat model of complex regional pain syndrome

“…(Gornikiewicz et al 2000) Also, it has been shown that terminal complement component mRNA levels could be increased in synovial cells and keratinocytes stimulated with various cytokines, whereas changes in complement protein levels could not be detected. (Guc et al 1993;Timar et al 2007) With a host of regulatory mechanisms controlling cytokine expression at the transcriptional, splicing, mRNA stability and translational levels, it is perhaps not surprising that fracture does not affect the levels of all cytokines in the same way. Thus a strength of our study is the measurement of both mRNA and cytokine protein levels.…”

Enhanced Bacteremia in Human Factor H Transgenic Rats Infected by Neisseria meningitidis

“…fH, however, is also synthesized de novo at various sites in the body, including the lung (6), skin fibroblasts (16), kidney (23,29), spleen (23), thymus (23), endothelial cells (25), and synovial fluid (11), and by primary human cervical epithelial cells (8). The newly developed human fH transgenic rat model expresses fH from a chicken betaactin promoter, which could result in expression of this protein at sites that do not normally express fH.…”

Discovery of distinctive gene expression profiles in rheumatoid synovium using cDNA microarray technology: evidence for the existence of multiple pathways of tissue destruction and repair

“…20 This could constitute an important pathway of tissue destruction, especially in combination with the high expression of immunoglobulins in these tissues, which are able to activate the classical pathway of complement, when complexed to antigens. The RA-Ia group, on the other hand, expressed genes encoding for proteins of the alternative pathway of complement, properdin (secreted by monocytes) 21 and factor I (secreted by fibroblasts and endothelial cells). This is rather surprising since the RA-Ia tissues also show a high expression of immunoglobulin genes.…”