Background: Rheumatoid arthritis is a chronic systemic disorder of unknown
etiology, that is characterized by inflammation, synovial hyperplasia and d
estruction of the affected joints. Novel molecular biology techniques have
identified important cellular and molecular pathways in the pathogenesis of
rheumatoid arthritis during the last years.
Results: The cellular activation of aggressively growing, matrix-degrading
synovial fibroblasts is a key event in the pathogenesis of rheumatoid arthr
itis. The cellular activation results in an altered expression of apoptosis
regulating molecules (for example CD 95 and Sentrin) as well a of protoonc
ogenes (for example RAS and MYC). Important extracellular stimuli such as t
he proinflammatory cytokines interleukin-1 and TNF-alpha are overexpressed
in the rheumatoid arthritis synovium. First clinical trials with cytokine i
nhibiting molecules (interleukin-1 receptor antagonist, recombinant soluble
TNF-alpha receptor/Etanercept and monoclonal TNF-alpha antibodies/Remicade
) revealed promising results. Etanercept is now available for the treatment
of rheumatoid arthritis in the USA. in addition, gene transfer methods cou
ld help to overcome the problem of a continuous expression of therapeutic m
olecules in the affected joints; gene delivery of the interleukin-1 recepto
r antagonist is currently tested in a human trial. Finally, the inhibition
of matrix degrading enzymes such as matrix metalloproteinases, that mediate
the joint destructive features of the activated synovial fibroblasts, coul
d be another therapeutic approach.
Conclusions: The elucidation of important molecular and cellular pathways i
n the pathogenesis resulted in novel concepts in the therapy of rheumatoid
arthritis. Gene transfer methods are of importance in studying the pathogen
esis of the disease, however, their clinical safety and usefulness have to
br proven ill additional studies.