<p>Thyroid eye disease (TED), an autoimmune disorder, involves critical interactions among immune cells that drive disease progression. However, the underlying mechanisms and their therapeutic potential remain unclear. This study profiled leukocyte composition in the peripheral blood of TED patients, revealing an elevated proportion of CD8⁺ T cells and distinct T-cell receptor (TCR) characteristics. Using a TSHR-targeting nucleic acid aptamer (TSHR-21-42), this study demonstrated a positive correlation between fibroblast proportion and TED activity. Histological examination further confirmed the interaction between CD8⁺ T cells and orbital fibroblasts. To inhibit this interaction, this study designed TSHR-CD80-1, a bispecific aptamer that simultaneously targets TSHR and CD80. In vitro experiments showed that TSHR-CD80-1 effectively interfered with the crosstalk between orbital fibroblasts and T cells while retaining the ability of TSHR-21-42 to suppress orbital fibroblast activation, adipogenic differentiation, hyaluronic acid secretion and fibrotic responses. In a TED mouse model, peri-ocular injection of TSHR-CD80-1 significantly alleviated systemic inflammation and reduced intra-orbital infiltration of CD8⁺ T cells, with no obvious adverse effects. In conclusion, the engineered aptamer TSHR-CD80-1 attenuates TED pathogenesis by inhibiting the interaction between CD8⁺ T cells and orbital fibroblasts.</p> Graphical Abstract <p></p>