Site-specific dimerization of interleukin-11 alleviates bleomycin-induced pulmonary fibrosis in mice

Interleukin-11 (IL-11) has recently been identified as a critical profibrotic cytokine, and IL-11 signaling pathway via IL-11Rα and GP130 receptors has been shown to be a promising therapeutic target for the treatment of fibrotic diseases. Herein, we devised two kinds of IL-11 dimer with receptor-biased binding ability through site-specific crosslinking at the interface involving GP130 binding and signaling, aiming to explore their therapeutic potentials for bleomycin-induced pulmonary fibrosis in mice. A single cysteine mutation at site W147 of human IL-11 (IL-11 W147C) was conducted for site-specific crosslinking. The ability of GP130 to bind to IL-11 W147C dimer was substantially weakened by cysteine-based dimerization, while the ability of IL-11 W147C dimer to bind to IL-11Rα was almost entirely preserved or even enhanced. The IL-11 W147C dimer potently inhibited TF-1 cell proliferation and TGF-β1-induced human lung fibroblast differentiation into myofibroblasts. We also showed that dimerization substantially extended the circulation time of IL-11 W147C dimer in healthy rats. Subcutaneous administration of IL-11 W147C dimer significantly reduced extracellular matrix deposition, preserved alveolar architecture and alleviated pulmonary fibrosis development in mice. The findings of this study may provide a general strategy for the design of cytokine-based receptor-biased antagonists and agonists targeting these multifaceted signaling pathways.