合成生物学助力突破免疫治疗局限性

doi:10.12211/2096-8280.2025-074

摘要/Abstract

摘要：

免疫治疗近年来在肿瘤、感染性疾病和自身免疫病等领域取得了突破性进展，但其临床应用仍面临信号识别特异性不足、免疫反应调控不精准及毒副作用显著等挑战。合成生物学作为一门新兴的工程化学科，通过模块化设计和基因回路编程，为免疫治疗的精准化改造提供了创新解决方案。本文系统综述了合成生物学在免疫治疗中的关键技术、应用案例及未来方向，旨在为免疫治疗的工程化设计提供理论依据和技术参考。在信号输入环节，工程化受体（如Syn-Notch、RASSL）通过逻辑门控设计（如“与”门）增强靶向性，减少脱靶效应；在信号处理环节，人工基因回路（如CHOMP、SPOC）将病理信号转化为治疗性输出，实现选择性杀伤或动态调控；在信号输出环节，反馈系统和振荡回路（如负反馈抑制T细胞过度活化）优化免疫反应强度与时长，提升安全性。此外，合成生物学技术已成功应用于CAR-T、CAR-NK等细胞疗法，通过受体改造、回路重编程等手段，显著提高了疗效并降低了毒性。未来，随着基因编辑、动态调控等技术的进一步发展，合成生物学驱动的免疫治疗将推动精准医学的实现，为复杂疾病的治疗提供更高效、更安全的策略。

关键词: 免疫治疗, 合成生物学, 基因回路, 癌症免疫治疗

Abstract:

Immunotherapy has revolutionized modern medicine by harnessing the body's immune system to combat malignancies, infectious diseases, and autoimmune disorders. Despite remarkable clinical successes, current immunotherapeutic approaches face substantial limitations, including inadequate target specificity, dysregulated immune activation, and severe systemic toxicities. These challenges stem from the inherent complexity of biological systems and the pleiotropic nature of immune responses. Synthetic biology emerges as a transformative paradigm to address these limitations through rational engineering of immune cells and circuits. This discipline applies engineering principles to biological systems, enabling the design of sophisticated genetic circuits that confer precise spatiotemporal control over immune functions. This review comprehensively examines current synthetic biology strategies in immunotherapy, highlighting their mechanistic basis, clinical applications, and future directions for advancing precision medicine. Key innovations include: (1) engineered receptor systems (e.g., Syn-Notch, RASSL) that implement Boolean logic operations for enhanced target discrimination; (2) synthetic signaling cascades (e.g., CHOMP, SPOC) that convert pathological signals into therapeutic outputs; and (3) feedback-regulated circuits that dynamically modulate immune effector functions. These technologies have been successfully implemented in chimeric antigen receptor (CAR)-based therapies, where they improve tumor specificity while mitigating cytokine release syndrome and other adverse effects. Notably, synthetic biology facilitates the development of "smart" immunotherapies capable of environmental sensing, decision-making, and self-regulation. For instance, conditionally activated CAR-T cells demonstrate improved safety profiles through drug-inducible control systems, while synthetic cytokine circuits enable precise immune modulation. Furthermore, the integration of computational modeling with high-throughput screening accelerates the optimization of these engineered systems. Looking forward, synthetic biology promises to bridge critical gaps in conventional immunotherapy by enabling: (1) personalized therapeutic regimens through patient-specific circuit design; (2) multi-input diagnostic capabilities for complex disease microenvironments; and (3) robust safety mechanisms to prevent off-target effects. As the field progresses, the convergence of genome editing, biomaterials science, and artificial intelligence will further expand the therapeutic potential of engineered immune cells.

Key words: immunotherapy, synthetic biology, genetic circuits, cancer immunotherapy

中图分类号:

Q816

王子恒, 刘子怡, 马毓谦, 秦鸿雁, 赵俊龙, 张向前. 合成生物学助力突破免疫治疗局限性[J]. 合成生物学, DOI: 10.12211/2096-8280.2025-074.

WANG Ziheng, LIU Ziyi, MA Yuqian, QIN Hongyan, ZHAO Junlong, ZHANG Xiangqian. Synthetic biology empowers breakthroughs in addressing immunotherapy limitations[J]. Synthetic Biology Journal, DOI: 10.12211/2096-8280.2025-074.

图/表 6

图1 工程化受体原理示意图（a） “RASSL”系统利用GPCR突变使得仅识别特定信号（蓝色）如小分子药物；（b）“Tango”系统利用β-arrestin与磷酸化GPCR空间位置的靠近启动蛋白酶切割释放转TF；（c） “Syn-Notch”系统利用notch受体激活的两次切割（胞外段ADAM17切割，近膜端γ-secretase切割）实现TF释放；（d）“GEMS”系统利用EPOR受体信号传导特点传递可编辑信号（胞外段及胞内段信号改构）；（e）”MESA”系统利用受体二聚化空间位置靠近启动蛋白酶切割释放TF。

Fig. 1 Schematic diagram of engineering receptor principle(a) The RASSL system utilizes GPCR mutations to recognize only specific signals (blue) such as small molecule drugs; (b) The "Tango" system utilizes the proximity of β-arrestin and phosphorylated GPCR spatial positions to initiate protease cleavage and release of TF; (c) the "Syn-Notch" system utilizes two cleavage processes activated by notch receptors (extracellular ADAM17 cleavage and proximal γ-secretase cleavage) to achieve TF release; (d) The GEMS system utilizes the signaling characteristics of EPOR receptors to transmit editable signals (extracellular and intracellular signal remodeling); (e) The "MESA" system utilizes receptor dimerization spatial proximity to initiate protease cleavage and release of TF.

表1 经典工程化受体优缺点

Table 1 Advantages and disadvantages of classical engineered receptors

工程化受体	优点	缺点
RASSL^[44,71]	1.GPCR种类繁多且可接受多种配体激活 2.改造GPCR结合配体特异性高	1. 依赖于突变 2. 受限于GPCR的配体种类 3. 局限于GPCR自身激活的通路
Tango^[53]	1.GPCR种类繁多且可接受多种配体激活 2.下游基因激活可编辑	受限于GPCR的配体种类
Syn-Notch^[60,72]	1. 受体与配体结合特异性高 2.配体可选择范围广 3.可实现广泛性的目的基因表达	仅用于与细胞之间的配受体结合
GEMS^[54]	1. 配体可选择范围广 2.配体可选择为游离性配体 3. 天然信号通路，信号传导成功率高 4. 同源二聚体，工作效率与改造成功率高 5. 自激活概率低	信号传导局限于可选择的天然信号通路
MESA^[68-69]	1配体可选择范围广 2.配体可选择为游离性配体 3. 能够选择性表达目的产物	1. 异二聚体工作效率低 2. 多种质粒转染，细胞负担大 3. 有概率自激活

图2 工程化元件原理示意图（a） “HTH”转录因子依赖信号（红色）二聚化后，成为带有转录激活因子（TA）的完整转录因子，启动下游基因表达；（b）“CHOMP”系统利用Ras信号通路激活后Ras与Raf的结合，实现蛋白酶TEV组装切割caspase3，引起细胞凋亡；（c） “SPOC”逻辑利用内源信号激活胞内蛋白酶（红色）切割无用卷曲螺旋（橙黄色）与效应卷曲螺旋（蓝色）之间的酶切位点，携带效应子卷曲螺旋（蓝色）相互结合引起效应子激活（黄色），启动下游基因转录；（d）“DART VADAR”系统利用工程化RNA链（红色）靶向目的RNA（蓝色，绿色），错配段引发ADARs修复终止密码子，转录得以继续。

Fig. 2 Schematic diagram of engineering components principle(a) After dimerization of the "HTH" transcription factor dependent signal (red), it becomes a complete transcription factor with transcription activator (TA), initiating downstream gene expression; (b) The "CHOMP" system uses the Ras signaling pathway to activate the binding of Ras and Raf, achieving the assembly and cleavage of caspase 3 by protease TEV, causing cell apoptosis; (c) The "SPOC" logic utilizes endogenous signals to activate intracellular proteases (red) to cleave enzyme cleavage sites between useless coiled coils (orange yellow) and effector coiled coils (blue), carrying effector coiled coils (blue) to bind with each other, causing effector activation (yellow) and initiating downstream gene transcription; (d) The "DART VADAR" system uses engineered RNA strands (red) to target the target RNA (blue, green), and mismatches trigger ADARs to repair stop codons, allowing transcription to continue.

图3 工程化环路原理示意图（a）双稳态系统中A，B两种核酸产物各自自激活与互相抑制，实现A，B两种状态的转变；（b）酵母中两种互相抑制的基因通过在其启动子与沉默位点下游改造实现整体负反馈调节，使得各自基因产物分开表达，实现细胞周期持续延长；（c） “LOCKR”系统利用KEY竞争性结合Cage使得Cage降解实现对Cage基因产物的控制，达到对调控Cage的信号（紫色）的耐受。

Fig. 3 Schematic diagram of engineering loop principle(a) In a bistable system, the two nucleic acid products A and B self-activate and mutually inhibit each other, achieving the transition between the two states of A and B; (b) Two mutually inhibitory genes in yeast achieve overall negative feedback regulation by downstream modification of their promoters and silencing sites, allowing their respective gene products to be expressed separately and achieving sustained cell cycle elongation; (c) The "LOCKR" system utilizes KEY competitive binding with Cage to control the degradation of Cage gene products, achieving tolerance to the signal (purple) that regulates Cage.

图4 合成生物学免疫治疗应用（a）syn-notch系统与CAR联合运用，肿瘤抗原一（红色）激活syn-notch促进CAR的表达，结合肿瘤抗原二（灰色），实现T细胞被肿瘤双抗原激活；（b）RASSL系统实现特定药物（蓝色）激活的细胞迁移信号；（c）CAR T/NK/macrophage示意图；（d）“RASER”系统示意图；（e） OspF 和YopH负反馈抑制TCR激活。(a) The syn notch system is used in combination with CAR. Tumor antigen one (red) activates syn notch to promote CAR expression, and when combined with tumor antigen two (gray), T cells are activated by tumor dual antigens; (b) RASSL system realizes cell migration signals activated by specific drugs (blue); (c) CAR T/NK/machophage schematic diagram; (d) RASER system schematic diagram; (e) OspF and YopH negative feedback inhibit TCR activation.

表2 不同CAR免疫细胞的比较

Table 2 Comparison of different CAR immune cells

1.肿瘤杀伤强： T细胞具有多种肿瘤杀伤手段，能够分泌穿孔素、颗粒酶引发肿瘤细胞死亡，通过死亡受体途径(Fas/FasL)引发肿瘤细胞凋亡，通过大量细胞因子分泌增强自身，抑制及杀伤肿瘤^[105]。

2.持久性强：T细胞一旦激活，能够大规模扩增，并在体内形成长期免疫记忆，提供持续的监视和杀伤效果^[106]。

3.杀伤效率高：T细胞杀伤肿瘤后并不会发生凋亡，可立即脱离寻找下一个肿瘤细胞^[107]。

4.技术相对成熟：是第一个成功商业化的细胞疗法，拥有大量的临床数据、生产工艺和经验^[108]。

1.毒副作用强：T细胞激活后细胞因子释放能力强，易造成细胞因子释放综合征^[105]

2.治疗实体瘤效果差：肿瘤免疫微环境使得T细胞迁移进入肿瘤的信号不足，难以浸润实体瘤^[109]。

3.自体来源为主：目前多为自体疗法，导致制备成本高、时间长^[109]。

4.可能脱靶：靶抗原在正常组织上也有低水平表达会导致T细胞攻击正常细胞^[105]。

CAR-NK

1.毒性低： NK细胞通过不同的机制杀伤靶细胞，不会引起严重的细胞因子释放^[110]。

2.通用性高：不同于T细胞这类适应性免疫细胞，NK细胞作为固有免疫细胞可以从健康供体的外周血、脐带血或NK细胞系扩增而来，有望成为通用型产品，成本更低^[111]。

3.对实体瘤潜力更大：具有更好的肿瘤组织浸润能力，且在肿瘤微环境中仍能保持一定的活性^[110-111]。

1.持久作用短： NK细胞在体内的存活时间较短，无法形成长期的免疫记忆^[111]。

2.增殖能力有限：在体内的增殖能力不如T细胞^[112]。

3.技术尚不成熟：实验数据与临床数据远少于CAR-T^[110,112]。

CAR-M

1.实体瘤浸润能力强：巨噬细胞天生具有浸润到实体瘤深部的能力^[113]。

2.具有重塑肿瘤微环境的能力：活化的CAR-M不仅能直接杀伤肿瘤，还能分泌细胞因子（如IFN-γ）将抑制性的M2型巨噬细胞转化为杀伤性的“M1型”，并招募其他的免疫细胞（如T细胞）到肿瘤部位^[113]。

3.吞噬作用：能够通过强大的吞噬作用直接吞噬肿瘤细胞^[113-114]。

4.通用性强：作为固有免疫细胞，可在体外大量扩增改造^[114]。

1.存在促瘤风险：巨噬细胞如果功能失调，反而可能被肿瘤微环境刺激成为M2型巨噬细胞，加重肿瘤进展^[114]。

2.肿瘤杀伤效率低：巨噬细胞随着吞噬肿瘤细胞数量增多，自身会发生凋亡，无法做到T细胞的持续杀伤^[113]。

3.体内增殖能力差：相较于T细胞，体内活化后的巨噬细胞增殖能力差^[114]。