Therapeutic effect of neutralizing endogenous IL-18 activity in the collagen-induced model of arthritis

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Abstract

Two distinct IL-18 neutralizing strategies, i.e. a rabbit polyclonal anti-mouse IL-18 IgG and a recombinant human IL-18 binding protein (rhIL-18BP), were used to treat collagen-induced–arthritic DBA/1 mice after clinical onset of disease. The therapeutic efficacy of neutralizing endogenous IL-18 was assessed using different pathological parameters of disease progression. The clinical severity in mice undergoing collagen-induced arthritis was significantly reduced after treatment with both IL-18 neutralizing agents compared to placebo treated mice. Attenuation of the disease was associated with reduced cartilage erosion evident on histology. The decreased cartilage degradation was further documented by a significant reduction in the levels of circulating cartilage oligomeric matrix protein (an indicator of cartilage turnover). Both strategies efficiently slowed disease progression, but only anti–IL-18 IgG treatment significantly decreased an established synovitis. Serum levels of IL-6 were significantly reduced with both neutralizing strategies. In vitro, neutralizing IL-18 resulted in a significant inhibition of TNF-α, IL-6, and IFN-γ secretion by macrophages. These results demonstrate that neutralizing endogenous IL-18 is therapeutically efficacious in the murine model of collagen-induced arthritis. IL-18 neutralizing antibody or rhIL-18BP could therefore represent new disease-modifying anti-rheumatic drugs that warrant testing in clinical trials in patients with rheumatoid arthritis.

Authors

Christine Plater-Zyberk, Leo A.B. Joosten, Monique M.A. Helsen, Pascale Sattonnet-Roche, Christiane Siegfried, Sami Alouani, Fons A.J. van de Loo, Pierre Graber, Shuki Aloni, Rocco Cirillo, Erik Lubberts, Charles A. Dinarello, Wim B. van den Berg, Yolande Chvatchko