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.