The effect of gold treatment on monocyte interleukin-1 production in rheumatoid arthritis. A prospective study

Effects of antirheumatic agents on cytokines

A review of the literature concerning the effects of traditional antirheumatic drugs on cytokines and the cytokine and anticytokine approaches already used in the therapy of rheumatoid arthritis (RA) is presented. Many antirheumatic drugs are capable of cytokine modulation in vitro. Corticosteroids inhibit the transcription of a broad spectrum of genes including those encoding monocyte, T cell-derived cytokines and several hemopoietic growth factors, whereas drugs such as cyclosporin A and D-penicillamine interfere with T cell activation more specifically by suppressing interleukin 2 (IL-2) production. The in vivo effects of drug therapy on cytokines in RA patients are less well established. Gold compounds reduce circulating IL-6 levels and the expression of monocyte-derived cytokines, such as IL-1, tumor necrosis factor (TNF), and IL-6, in the rheumatoid synovium. Decreases in circulating IL-6, soluble IL-2 (sIL-2R), and TNF receptors and in synovial fluid IL-1 levels have been reported with methotrexate. Reductions in circulating IL-6 and sIL-2R concentrations have also been observed with cyclosporin and corticosteroids, whereas azathioprine reduces IL-6 but not sIL-2R. Studies on sulfasalazine are conflicting and the in vivo effects of D-penicillamine and antimalarials have not been studied yet. Interferon gamma therapy is not effective in RA but may prove a useful antifibrotic for systemic sclerosis. Colony stimulating factors improve the granulocytopenia associated with Felty's syndrome or drug toxicities but can induce arthritis flares and should be reserved to treat infectious complications. Promising results are being obtained with selective antagonism of TNF and IL-1 in RA, and combinations of anticytokine strategies with traditional antirheumatic drugs have been already envisaged. These should preferably be based in a broader knowledge of the effects of antirheumatic agents on the cytokine network.

Cytokine production by normal human monocytes: inter-subject variation and relationship to an IL-1 receptor antagonist (IL-1Ra) gene polymorphism

Monocytes from different individuals show variable cytokine production in response to a variety of stimuli. We wished to determine the sets of conditions (cytokine combinations) that would enable us to demonstrate stable inter-individual differences in the production of IL-1 alpha, IL-1 beta, IL-1Ra, on-6 and tumour necrosis factor-alpha (TNF-alpha) by monocytes. We assessed the ability of a number of recombinant human cytokines (granulocyte-macrophage colony-stimulating factor (GM-CSF), interferon-gamma (IFN-gamma), TNF-alpha, IL-4, IL-6, transforming growth factor-beta (TGF-beta), IL-10 and IL-1Ra)) to stimulate or inhibit the production of one or more of these monocyte products. GM-CSF was found to stimulate the production of all five of these cytokines in a highly reproducible manner. TNF-alpha also up-regulated production of IL-1 alpha, IL-1 beta, IL-1Ra and IL-6 by monocytes, but the variability in the results of cells cultured from the same individuals on different occasions was greater. Other cytokines either stimulated production of only some of the five cytokine products tested, or stimulated the production of some cytokine products while inhibiting production of others. This was especially evident when cytokines were used in combination with GM-CSF: IFN-gamma down-regulated production of IL-1Ra while up-regulating the production of IL-1 alpha/beta, IL-6 and TNF-alpha, while IL-4 had the exact opposite effect. Polymorphisms in regions of cytokine genes that affect transcription may account for some of the interindividual variation in cytokine production. We have shown that a stable estimate of cytokine production phenotype can be obtained when monocytes collected on at least two separate occasions are stimulated by GM-CSF in vitro. We have looked for a relationship between IL-1 production and an 86-bp variable repeat polymorphism in intron 2 of the IL-1Ra gene. A less common allele of this polymorphism (allele 2) was associated with increased production of IL-1Ra protein, and also reduced production of IL-1 alpha protein by monocytes.