A lesion-selective albumin-CTLA4Ig as a safe and effective treatment for inflammatory diseases

李之勤1,*, 戴源宏2, 姜富耀2, 周芊妤2, 黃筱真1, 鄒協成1,2,#

1國立陽明大學生物科技研究所, 2國立陽明大學生物暨分子生物研究所

Zhi-Qin Li1,* Yuan-Hong Tai2, Fu-Yao Jiang2, Chien-Yu Chou2, Hsiao-Chen Huang1, Shey-Cherng Tzou1,2,3

1 1Department of Biological Science and Technology, National Yang Ming Chiao Tung University, 2Institution of biochemistry and molecule biology, National Yan-Ming University

CTLA4Ig is a fusion protein of the extracellular domain of cytotoxic T-lymphocyte protein 4 (CTLA4) and an Fc fragment of a human IgG1, currently approved for treating inflammatory diseases such as rheumatoid arthritis. However, CTLA4Ig can induce adverse effects likely due to systemic inhibition of T cells. Developing an inflammatory tissue-selective variant of CTLA4Ig may improve the safety while maintaining the efficacy of the treatment. To develop a pro-CTLA4Ig variant whose function is masked in physiological conditions, we linked albumin to the N-terminus of CTLA4Ig (termed Alb-CTLA4Ig) via a substrate sequence of matrix metalloproteinase (MMP). Alb-CTLA4Ig was stable and inactive under physiological conditions but can be fully activated by MMPs. The binding activity of the non-digested Alb-CTLA4Ig was estimated 10,000-fold weaker than the MMP-digested Alb-CTLA4Ig in the cell-based ELISA. The non-digested Alb-CTLA4Ig was unable to inhibit IL-2 production by activated Jurkat T cells, whereas the MMP-digested Alb-CTLA4Ig was as potent as the conventional CTLA4Ig in blocking the T cells. We demonstrate that Alb-CTLA4Ig was targeted and activated in the inflamed joints of mice that developed collagen-induced arthritis (CIA), where it may bind to synovial-infiltrating cells that expressed CD80. Furthermore, Alb-CTLA4Ig showed similar efficacy as the conventional CTLA4Ig in treating CIA. Importantly, Alb-CTLA4Ig did not inhibit the anti-microbial responses in the spleens while suppressing the joint inflammation in the treated mice. Alb-CTLA4Ig can be activated by MMPs overexpressed in inflammatory tissues to suppress tissue inflammation selectively, thus, Alb-CTLA4Ig may be an effective and safe treatment for inflammatory diseases.