LAUSR

Graphical abstract Figure. No caption available. ABSTRACT This study was undertaken to generate a novel dual targeting fusion protein (DTF), targeting tumor necrosis factor &agr; (TNF‐&agr;) and interleukin 17A (IL‐17A), and determine its anti‐arthritis properties in vitro and in vivo. DTF consisted of an anti‐IL‐17A single chain variable fragment, a soluble TNF receptor 1, and an Fc fragment. Both clinical and histopathological evaluations suggest that DTF and etanercept can ameliorate collagen induced arthritis. However, the arthritis severity score of DTF‐treated mice was lower than that of etanercept‐treated mice. In addition, DTF was more potent than etanercept in decreasing the ratio of RANKL/OPG in the serum and rebalancing the population ratio of Treg/Th17 cells in the spleens. In vitro, IL‐17A and TNF‐&agr; had synergistic effects in inducing the expression of inflammatory cytokines in fibroblast‐like synoviocyte from RA patients (RA‐FLS), human leukemia (THP‐1), and rheumatoid synovial fibroblast (MH7A). IL‐17A and TNF‐&agr; also had synergistic effects in inducing proliferation and migration of MH7A cells. However, we observed that DTF was more efficient than etanercept in suppressing these synergistic effects. Our results demonstrate that DTF is highly efficient in the treatment of arthritis and has the potential to overcome the limited therapeutic responses obtained with single cytokine neutralization.