[Present and future therapeutic strategies in rheumatoid arthritis].
The triad of inflammation, immunoproliferation and synovial hyperplasia is recognized in the pathogenesis of rheumatoid arthritis, however, the sequence of events remains as highly controversial as ever. The "RA pyramid" was established on the assumption that inflammation is at the top with the destructive processes as sequelae. The moderate successes achieved by conservative therapy with regard to long-term outcome cast doubt on this hypothesis. Inhibitors of prostaglandin synthesis have not been and are not disease modifying. Do substances which influence the endothelial adhesion molecules or leucocyte adhesion receptors (leumedines) promise to be more successful? Do the empirically developed disease modifying antirheumatic drugs (Gold parenteral, MTX) have to be administered earlier? Unfortunately, there is a need for a differential diagnosis which is prognostically valid with regard to the dynamics and aggressiveness of rheumatoid arthritis. Moreover, a pharmacological basis for optimally founded combination strategies is also lacking. Presently, the emphasis of research is directed at the regulation of dysfunctional immune systems. Immunosuppressives (cyclosporin A), cytokine antagonists, receptor antagonists and soluble cytokine receptors (IL-1, IL-6, TNF-alpha), antibodies against lymphocyte subgroups (CD4, CD7) or against cytokines and their receptors are part of the arsenal for the medium term. Too little is still known about the role of protective cytokines (TGF-beta, IL-4, gamma-INF). Currently, however, it is prognosticated that these targeted therapies will only succeed in RA subgroups or only in intelligent combinations. More attractive alternative are strategic therapy modalities which intervene very early in the pathological process, such as the modulation of antigen presentation (MHC blocking peptides, T-cell receptor antagonists, T-cell vaccination) or the induction of tolerance against autoantigens through the oral administration of antigens (collagen II, HSP's, OM-8980). If the center of the pathological process, however, is found in the synovial proliferation of tumor-like cell clusters, then there are only a few years at the beginning of the disease when there is a real chance to impede destruction. In this case, aggressive induction therapy can be the only key to success. In the future, specifically active cytostatics (inhibitors of angiogenesis) will have to be developed and clinical trials conducted on adjuvant therapies with substances which strengthen bone and cartilage, making them more resistant to aggressive cell clusters (bisphosphonates, calcitonins, metalloproteinase- or collagenase-inhibitors).