Abstract：
Immune-checkpoint blockade (ICB) reinvigorates T cells from exhaustion and potentiates T-cell responses to tumors. However, most patients do not respond to ICB therapy, and only a limited response can be achieved in a \"cold\" tumor with few infiltrated lymphocytes. Synthetic biology can be used to engineer bacteria as controllable bioreactors to synthesize biotherapeutics in situ. We engineered attenuated Salmonella VNP20009 with synthetic gene circuits to produce PD-1 and Tim-3 scFv to block immunosuppressive receptors on exhausted T cells to reinvigorate their antitumor response. Secreted PD-1 and Tim-3 scFv bound PD-1+ Tim-3+ T cells through their targeting receptors in vitro and potentiated the T-cell secretion of IFN-γ. Engineered bacteria colonized the hypoxic core of the tumor and synthesized PD-1 and Tim-3 scFv in situ, reviving CD4+ T cells and CD8+ T cells to execute an antitumor response. The bacteria also triggered a strong innate immune response, which stimulated the expansion of IFN-γ+ CD4+ T cells within the tumors to induce direct and indirect antitumor immunity.
摘要：
免疫检查点阻断(ICB)使T细胞免于耗尽并增强对肿瘤的T细胞应答。然而,大多数患者对ICB治疗没有反应，在具有少量浸润淋巴细胞的“冷”肿瘤中，只能实现有限的反应。合成生物学可用于工程化细菌作为可控生物反应器以原位合成生物治疗剂。我们设计了具有合成基因回路的减毒沙门氏菌VNP20009，以产生PD-1和Tim-3scFv，以阻断耗尽的T细胞上的免疫抑制受体，以恢复其抗肿瘤反应。分泌的PD-1和Tim-3scFv通过它们的靶向受体在体外结合PD-1+Tim-3+T细胞并增强IFN-γ的T细胞分泌。工程化细菌定植于肿瘤的缺氧核心，并原位合成PD-1和Tim-3scFv，恢复CD4+T细胞和CD8+T细胞以执行抗肿瘤反应。这种细菌还引发了强烈的先天免疫反应，其刺激肿瘤内IFN-γ+CD4+T细胞的扩增以诱导直接和间接的抗肿瘤免疫。
