Interleukin-10 (IL-10) is a dimeric cytokine with both immunosuppressive and immunostimulatory activities; however, IL-10–based therapies have shown only marginal clinical benefits. Here, we explored whether the stability of the IL-10 receptor complex contributes to the immunomodulatory potency of IL-10. We generated an IL-10 mutant with enhanced affinity for its IL-10Rβ receptor using yeast surface display. Compared to the wild-type cytokine, the affinity-enhanced IL-10 variants recruited IL-10Rβ more efficiently into active cell surface signaling complexes and triggered greater STAT1 and STAT3 activation in human monocytes and CD8⁺ T cells. These effects, in turn, led to more robust induction of IL-10–mediated gene expression programs at low ligand concentrations in both human cell subsets. IL-10–regulated genes are involved in monocyte energy homeostasis, migration, and trafficking and in CD8⁺ T cell exhaustion. At nonsaturating doses, IL-10 did not induce key components of its gene expression program, which may explain its lack of efficacy in clinical settings. Our engineered IL-10 variant showed a more robust bioactivity profile than that of wild-type IL-10 at low doses in monocytes and CD8⁺ T cells. Moreover, CAR-modified T cells expanded with the engineered IL-10 variant displayed superior cytolytic activity than those expanded with wild-type IL-10. Our study provides insights into how IL-10 receptor complex stability fine-tunes IL-10 biology and opens new opportunities to revitalize failed IL-10 therapies.

Interleukin-10 (IL-10) 是一种二聚体细胞因子，具有免疫抑制和免疫刺激活性；然而，基于 IL-10 的疗法仅显示出微不足道的临床益处。在这里，我们探讨了 IL-10 受体复合物的稳定性是否有助于 IL-10 的免疫调节效力。我们使用酵母表面展示产生了对其 IL-10Rβ 受体具有增强亲和力的 IL-10 突变体。与野生型细胞因子相比，亲和力增强的 IL-10 变体能更有效地将 IL-10Rβ 募集到活性细胞表面信号复合物中，并在人单核细胞和 CD8 ^{+ 中}引发更大的 STAT1 和 STAT3 激活T细胞。反过来，这些效应导致在两个人类细胞亚群中以低配体浓度更有效地诱导 IL-10 介导的基因表达程序。IL-10 调节的基因参与单核细胞能量稳态、迁移和运输以及 CD8 ⁺ T 细胞耗竭。在非饱和剂量下，IL-10 不会诱导其基因表达程序的关键组成部分，这可能解释了其在临床环境中缺乏疗效的原因。我们的工程化 IL-10 变体在低剂量的单核细胞和 CD8 ^{+ 中}显示出比野生型 IL-10 更强大的生物活性特征T细胞。此外，用工程化 IL-10 变体扩增的 CAR 修饰的 T 细胞显示出比用野生型 IL-10 扩增的细胞更好的细胞溶解活性。我们的研究提供了关于 IL-10 受体复合物稳定性如何微调 IL-10 生物学的见解，并为振兴失败的 IL-10 疗法开辟了新的机会。