title: Synthesis of metalloproteases and interleukin 6 (IL-6) in human osteoarthritic synovial membrane is an IL-1 mediated process.
abstract: We investigated the nature of cytokines synthesized by human osteoarthritic (OA) synovium, particularly interleukin 1 alpha (IL-1 alpha), interleukin 1 beta (IL-1 beta), and tumor necrosis factor alpha (TNF alpha). We examined the capacity of recombinant human interleukin 1 receptor antagonist (rhIL-1ra) to block the synthesis of metalloproteases (collagenase and stromelysin), IL-1 beta, and IL-6 in osteoarthritis (OA) synovium. Human OA synovium were incubated in the presence or absence of lipopolysaccharide (LPS) or increasing concentrations of rhIL-1ra. The determinations of IL-1 alpha, IL-1 beta, TNF alpha, IL-6, and IL-1ra in culture medium were carried out using specific ELISA. Although both IL-1 isoforms and TNF alpha could be produced by OA synovium, IL-1 beta was the predominant cytokine synthesized either in the presence or absence of LPS. Treatment of the OA synovium with an increasing concentration of rhIL-1ra (0-10 micrograms/ml) showed a dose dependent reduction of both metalloproteases and IL-6. Maximal inhibition was 70% for collagenase, 80% for stromelysin, and 76% for IL-6. LPS treated synovium also showed a consistent suppression of metalloproteases and IL-6, although a higher IL-1ra concentration was required. Conversely, IL-1 beta production was not inhibited by IL-1ra, irrespective of the concentration used and whether the membranes were LPS stimulated. These data showed that IL-1 appears to be the major autocrine cytokine involved in the stimulation of metalloproteases and IL-6 synthesis in OA synovium.
authors.affiliation: Louis-Charles Simard Research Center, Notre-Dame Hospital, Department of Medicine, University of Montreal, PQ, Canada.
authors.forename: J P
authors.initials: JP
authors.lastname: Pelletier
authors.forename: R
authors.initials: R
authors.lastname: McCollum
authors.forename: J M
authors.initials: JM
authors.lastname: Cloutier
authors.forename: J
authors.initials: J
authors.lastname: Martel-Pelletier
mesh_terms: D046508:Culture Techniques; D016207:Cytokines / Q000096:biosynthesis* / Q000187:drug effects; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D053590:Interleukin 1 Receptor Antagonist Protein; D007375:Interleukin-1 / Q000096:biosynthesis / Q000502:physiology*; D015850:Interleukin-6 / Q000096:biosynthesis*; D008070:Lipopolysaccharides / Q000494:pharmacology; D008666:Metalloendopeptidases / Q000096:biosynthesis* / Q000187:drug effects; D010003:Osteoarthritis / Q000276:immunology / Q000378:metabolism*; D017472:Receptors, Interleukin-1 / Q000037:antagonists & inhibitors; D012795:Sialoglycoproteins / Q000494:pharmacology; D013583:Synovial Membrane / Q000276:immunology / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis
chemical_list: D016207:Cytokines; C507763:IL1RN protein, human; D053590:Interleukin 1 Receptor Antagonist Protein; D007375:Interleukin-1; D015850:Interleukin-6; D008070:Lipopolysaccharides; D017472:Receptors, Interleukin-1; D012795:Sialoglycoproteins; D014409:Tumor Necrosis Factor-alpha; D008666:Metalloendopeptidases