抗体製薬を用いたInterleukin 6阻害療法から学んだ自己免疫疾患に対する治療戦略

Abstract

Remarkable clinical effects were observed by IL-6 blockage with a humanized anti IL-6 receptor antibody in patients with Castleman's disease, rheumatoid arthritis, and juvenile inflammatory arthritis. This evidence suggests that the hyper-function of IL-6 is an essential key cytokine in the pathogenesis of the above diseases, in which many cytokines, chemokines, and inflammatory molecules are activated. We found, for example, TNF-alpha blocking therapy showed a reduction of acute phase proteins, such as CRP and SAA, however, the IL-6 blockade induced not only reduction but also normalization of CRP and SAA serum levels. To elucidate this in vivo phenomenon, we analyzed the expression of cytokine inducing CRP and SAA mRNA with the intracellular signal transduction mechanism in vitro. The results, indicated that the IL-6 signal was essential though the activation of STAT3 for the induction and augmentation of CRP or SAA by the associated stimulation with TNF-alpha or IL-1. Recently, it is now known that IL-6 is a regulatory molecule in the induction of Th17 cells with TGF-beta. Therefore, IL-6 blockage may potentially improve autoimmune diseases, beginning with the pathogenic initiation phase. We believe that unknown pathogenic inflammatory phenomena can be clarified using this analytical strategy and cytokine blocking therapy. Furthermore, in the future we hope to induce complete remission of autoimmune diseases by using cytokine blockage freely.