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A radicicol analogue (analogue A) was found to inhibit interleukin 1 beta (IL-1 beta) and tumour necrosis factor alpha (TNF-alpha) secretion from THP-1 cells. If added to cells activated by interferon gamma and lipopolysaccharide, radicicol analogue A not only inhibited the secretion of IL-1 beta but also induced an extremely rapid degradation of IL-1 beta, IL-6 and TNF-alpha mRNA to undetectable levels within 5-8 h. This degradation is independent of translation and of the signal inducing transcription. The common feature of these genes is the inclusion of one or more copies of the mRNA-instability sequence, AUUUA, in the 3' untranslated region. Indeed, no destabilizing effect of radicicol analogue A could be observed on mRNA derived from the expression of an IL-1 beta construct lacking the AUUUA motifs of the 3'UTR. The effect of radicicol analogue A on protein/mRNA interaction and on post-translational modifications of cytoplasmic proteins is described. This class of compound constitutes a valuable tool for the further elucidation of the mechanism of mRNA degradation of cytokines and proto-oncogenes.

Compound IX 207-887 is a novel antiarthritic agent which inhibits the release of interleukin-1 (IL-1) from human monocytes and mouse peritoneal macrophages in vitro at concentrations which are achieved therapeutically in human rheumatoid arthritis and in animal models of arthritis. In the present studies IL-1 activity in conditioned media, homogenates or lysates was monitored using four independent assay systems. Biologically active IL-1 was determined by, a) the induction of latent metalloproteinase-release from rabbit articular chondrocytes, which is relatively specific for IL-1 and b) by a sensitive thymocyte proliferation assay. Immunoreactive IL-1-beta was assayed by RIA and ELISA. In all test systems IX 207-887 significantly reduced both biologically active and immunoreactive IL-1 in culture media, whereas the levels of IL-1 in homogenates or lysates were either unaffected or only marginally reduced. The release of other monokines tested, such as interleukin-6 and tumour necrosis factor-alpha, and the secretion of lysozyme were only marginally influenced. IX 207-887 neither affected the adherence of human monocytes nor markedly inhibited IL-1 or IL-2-induced thymocyte proliferation. In the chondrocyte test no IL-1 antagonistic activity of IX 207-887 could be observed. All of these data indicate that IX 207-887 has the novel property of being an inhibitor of IL-1 release.

Cytokines such as Interleukin-1 (IL-1) are important modulators of the cell-mediated immune response and play a paramount role in inflammatory autoimmune disease. We report on preliminary clinical experiences with a new, tricyclic substance [( 10-Methoxy-4H-benzo[4,5]cyclo-hepta-[1,2-b]thiophene-4- ylidene]acetic acid, MW 284), which inhibits the release of interleukin-1 alpha and -beta from cultured murine macrophages or human mononuclear cells. The study included 12 patients (rheumatoid arthritis, n = 9; hemochromatotic arthropathy, n = 1; psoriatic arthropathy, n = 1; seronegative spondylarthropathy, n = 1). Eight patients were treated for a total of 8 weeks, receiving a median dose of 800 mg/d of the substance. Due to significant clinical benefits, two patients continued for a total of six months. Administration of the drug was discontinued in two patients because of severe urticaria and lack of compliance, respectively. Four out of 10 patients showed clinical improvement according to Ritchie-Index, pain score, ESR and CRP. Side effects were diffuse gastrointestinal symptoms (4/12), temporary impairment of liver function (4/12) and allergic skin reactions (3/12).

Macrophage products induce production of proteases that contribute to cartilage degradation in various joint diseases. In these studies we stimulated rabbit chondrocytes with various cytokines in vitro in order to determine which were responsible for changes in the release of prostaglandin, plasminogen activator, and a metalloproteinase. The metalloproteinase assayed in these studies is a latent enzyme whose activity can rapidly be measured with fluorogenic casein. Conditioned media from stimulated human peripheral blood mononuclear cells; purified human monocyte IL 1, pI 7,6, and 5; and recombinant human IL 1, beta or alpha forms, all changed the secretory pattern of rabbit articular chondrocytes in a similar manner: production and secretion of a latent metalloproteinase(s) and prostaglandin E were stimulated in a concentration-dependent fashion, whereas the activity of plasminogen activator was strongly reduced. Antibodies against human monocyte IL 1 blocked the active principle in various mononuclear cell-conditioned media, suggesting that uncharacterized factors present in these supernatants do not affect the metalloproteinase response. When added to confluent chondrocytes, phorbol myristate acetate, concanavalin A, IL 2, lipopolysaccharide, indomethacin, and prostaglandin E2, which interfere with lymphocyte proliferation assays for IL 1, failed to influence chondrocyte metalloproteinase secretion. Recombinant human IFN-alpha or IFN-gamma in the presence or absence of IL 1 had no effect on rabbit chondrocytes, whereas recombinant human tumor necrosis factor decreased plasminogen activator but had no effect on prostaglandin or metalloproteinase production. These results support the concept that IL 1 specifically induces chondrocytes to produce metalloproteinases, and hence may play an important role in destructive joint diseases.