PO.ET04.01 · 实验与分子治疗
通过鞭毛分泌系统分泌IFN-β的减毒Salmonella增强抗肿瘤免疫和治疗疗效
Attenuated Salmonella secreting IFN-beta via the flagellar secretion system enhances antitumor immunity and therapeutic efficacy
作者与单位 Authors & Affiliations
摘要 Abstract
中文摘要
目的：细菌癌症治疗提供了一种靶向肿瘤组织并调节免疫微环境的独特方法。在此，我们旨在建立一个能够通过鞭毛III型分泌系统（FT3SS）分泌干扰素-β（IFN-β）的减毒Salmonella平台以增强抗肿瘤免疫，并评估其作为单药治疗以及与PD-L1阻断联合的治疗疗效。
方法：通过从亲本BRD509背景中删除rcsB基因构建减毒鼠伤寒Salmonella菌株，并经工程改造使其在L-阿拉伯糖诱导下通过FT3SS分泌IFN-β。通过Western blot和ELISA验证IFN-β分泌。使用IVIS生物发光成像评估该菌株的生物分布。在CT26荷瘤小鼠中，通过评估肿瘤生长抑制、凋亡和免疫细胞激活，评估了分泌IFN-β的Salmonella诱导的抗肿瘤疗效和免疫激活。进行了与抗PD-L1抗体的联合治疗以增强治疗效果。此外，通过监测血清肝肾功能标志物、体重以及主要器官的H&E组织学，确认了该菌株的体内安全性。
结果：本研究中，我们开发了一种能够通过FT3SS分泌IFN-β的减毒Salmonella菌株。IFN-β分泌受L-阿拉伯糖诱导调控而不影响Salmonella菌株的活力。表达Lux的分泌IFN-β Salmonella的体内生物发光成像显示快速的肿瘤定植和选择性瘤内增殖，证实了其肿瘤靶向能力。在CT26荷瘤小鼠中，用分泌IFN-β菌株治疗并于注射后第3天起进行L-阿拉伯糖诱导，抑制了肿瘤生长并诱导了肿瘤细胞凋亡。该治疗还促进了N1型中性粒细胞浸润和抗肿瘤免疫应答的激活，并在体内确认了其安全性。然而，IFN-β单药治疗未能完全根除肿瘤，且在细菌注射后肿瘤组织中PD-L1表达上调。因此，分泌IFN-β的Salmonella与抗PD-L1抗体的联合治疗产生了协同抗肿瘤效应，包括相比任一单药治疗显著增强的肿瘤消退和延长的生存期。这些结果凸显了这一可控细菌平台用于下一代癌症免疫治疗的临床潜力。
结论：总体而言，这些发现证明基于FT3SS的分泌IFN-β的Salmonella代表了一种安全、强效且通用的治疗平台，可增强抗肿瘤免疫并与免疫检查点阻断协同作用。
查看英文原文 English abstract
Purpose: Bacterial cancer therapy offers a unique approach to target tumor tissues and modulate the immune microenvironment. Here, we aimed to establish an attenuated Salmonella platform capable of secreting interferon-beta(IFN-beta) through the flagellar type III secretion system(FT3SS) to potentiate antitumor immunity, and to evaluate its therapeutic efficacy as monotherapy and in combination with PD-L1 blockade.
Methods: The attenuated Salmonella Typhimurium strain was constructed by deleting the rcsB gene from the parental BRD509 background and engineered to secrete IFN-beta through the FT3SS under L-arabinose induction. IFN-beta secretion was verified by Western blot and ELISA. The biodistribution of the strain was evaluated using IVIS bioluminescence imaging. The antitumor efficacy and immune activation induced by the IFN-beta secreting Salmonella were assessed in CT26 tumor-bearing mice by evaluating tumor growth inhibition, apoptosis, and immune cell activation. Combination therapy with an anti-PD-L1 antibody was performed to potentiate the therapeutic effect. In addition, the in vivo safety of the strain was confirmed by monitoring serum liver and kidney function markers, body weight, and H&E histology of major organs.
Results: In this study, we developed an attenuated Salmonella strain capable of secreting IFN-beta through the FT3SS. IFN-beta secretion was regulated by L-arabinose induction without affecting the viability of the Salmonella strain. In vivo bioluminescence imaging of Lux-expressing IFN-beta secreting Salmonella demonstrated rapid tumor colonization and selective intratumoral proliferation, confirming its tumor-targeting capability. In CT26 tumor-bearing mice, treatment with the IFN-beta secreting strain followed by L-arabinose induction from day 3 post-injection inhibited tumor growth and induced tumor cell apoptosis. The therapy also promoted N1-type neutrophil infiltration and activation of antitumor immune responses, and its safety was confirmed in vivo . However, IFN-beta monotherapy did not completely eradicate tumors, and PD-L1 expression was upregulated in the tumor tissues after bacterial injection. Therefore, combination therapy with the IFN-beta secreting Salmonella and an anti PD-L1 antibody resulted in synergistic antitumor effects, including markedly enhanced tumor regression and prolonged survival compared to either monotherapy. These results highlight the clinical potential of this controllable bacterial platform for next-generation cancer immunotherapy.
Conclusion: Overall, these findings demonstrate that the FT3SS-based IFN-beta secreting Salmonella represents a safe, potent, and versatile therapeutic platform that enhances antitumor immunity and synergizes with immune checkpoint blockade.
利益披露 Disclosure
K. Eunji, None.