Blocking GP130 binding in interleukin-11 through site-specific PEGylation attenuates bleomycin-induced pulmonary fibrosis in mice.

Recent insights have identified interleukin-11 (IL-11) as a pivotal profibrotic cytokine, with its signaling through IL-11Rα and GP130 receptors emerging as a promising therapeutic target for fibrotic diseases. Herein, we developed receptor-biased IL-11 via site-specific PEGylation at the GP130 binding interface, aiming to explore its therapeutic potential for bleomycin-induced pulmonary fibrosis in mice. By conducting single site-directed cysteine mutagenesis at site II or site III of IL-11, we refined the conjugation site, demonstrating that mutation at site III exhibits heightened sensitivity to GP130 binding and signaling. Cysteine-based PEGylation substantially attenuated the ability of GP130 to bind to IL-11 W147C, while almost entirely preserving its IL-11Rα binding ability. These PEGylated IL-11 W147C analogs showed potent inhibition of TF-1 cell proliferation and significant antagonism to TGF-β1-induced human lung fibroblasts (HLFs) differentiation into myofibroblasts. Moreover, PEGylation significantly prolonged the half-life of IL-11 W147C in healthy rats. Subcutaneous administration of PEGylated analogs, particularly PEG20/40 k-IL-11 W147C, effectively mitigated extracellular matrix deposition, preserved alveolar architecture, and attenuated the progression of pulmonary fibrosis in mice. The finding of this study not only underscores the therapeutic potential of IL-11 modulation, but also provides a general strategy for the design of cytokine-based biased antagonists and agonists targeting these multifaceted signaling pathways.