Ultrasensitive antigen density discrimination by synNotch.
Ultrasensitive antigen density discrimination by synNotch.
复制标题
通过 synNotch 进行超灵敏抗原密度辨别。
DOI：
10.1038/s41422-021-00511-y
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发表时间：
2021
期刊：
影响因子：
44.1
通讯作者：
Riley,JamesL
中科院分区：
文献类型：
--
作者：
Shukla,Divanshu;Riley,JamesL
在最近发表在《科学》杂志上的一项研究中，Hernanal-Lopez等人设计了一种从低到高的两步调节电路，使T细胞能够以超灵敏的阈值区分靶抗原。在该回路中，低亲和力synNotch受体控制高亲和力嵌合抗原受体（CAR）的表达;嵌合抗原受体（CAR）T细胞已经显示出治愈表达CD 19的肿瘤的令人印象深刻的能力，但是这些工程化的T细胞总是具有“靶向，这种“肿瘤外”毒性会损伤正常组织，阻碍靶向其他肿瘤的CAR T细胞的发展。事实上，存在与CD 19特异性汽车相关的显著的靶向、脱肿瘤毒性，其中最明显的受害者是B细胞。幸运的是，有治疗方案可以最大限度地减少这些免疫细胞的损失。然而，最近在脑壁细胞中检测到CD 19表达，这可能与在某些个体中观察到的神经毒性有关。[1]这表明，并不存在仅在“肿瘤”组织上表达的独特肿瘤标志物或抗原，而是一组具有细胞外结构域的蛋白质，它们主要在肿瘤上不同程度地表达，在健康组织上表达较少。已经提出了几种策略，将CAR T细胞集中在肿瘤上，而不太关注健康组织。在一份报告中，用CAIX mAb预处理阻断了工程化T细胞接近胆管上皮细胞中表达的CAIX，降低了CAIX CAR T细胞的中靶、脱瘤毒性。3在另一种策略中，通过用T细胞活化的负调节因子PD-1或CTLA-4的抑制性信号传导链取代细胞质信号传导结构域来工程化拮抗性受体系统，抑制性汽车（iCAR）。在临床前研究中，iCAR允许T细胞将靶抗原与旁观者细胞区分开来，并限制肿瘤外细胞因子分泌和细胞毒性。虽然这些方法有希望，但它们试图限制完全胜任的CAR T细胞的活性，这可能会证明在长期基础上具有挑战性。另一方面，synNotch受体被开发为仅允许在正确的环境线索下表达全功能CAR构建体。在此，细胞外Notch结构域被传感器模块（例如，ScFv）替换，并且细胞内结构域系留转录调节因子。在靶抗原与synNotch受体接合后，正交转录因子（例如TetR-VP 64或Gal 4-VP 64）以ADAM和γ-分泌酶依赖性方式从细胞质尾区切割，并且该转录因子驱动功能性CAR构建体的表达。在synNotch受体的最初应用中，T细胞被改造为仅在另一种分子存在时表达CAR。这样，肿瘤可以被定义为
In a recent study published in Science, Hernandez-Lopez et al. engineered a low-to-high two-step regulatory circuit that allows T cells to discriminate target antigens with an ultrasensitive threshold. In this circuit, low-affinity synNotch receptor controls the expression of the high-affinity chimeric antigen receptor (CAR); thus, the only time the CAR construct is expressed is in the presence of high levels of antigen, preventing off-tumor CAR T cell recognition.Chimeric antigen receptor (CAR) T cells have shown an impressive ability to cure CD19-expressing tumors, but these engineered T cells invariably have “on-target, off-tumor” toxicity that injure the normal tissues, hindering the development of CAR T cells targeting other tumors. Indeed, there are significant ontarget, off-tumor toxicities associated with CD19-specific CARs, with the most noticeable victim being B cells. Fortunately, there are therapeutic options to minimize the loss of these immune cells. However, CD19 expression has recently been detected in brain mural cells, which may be related to the neurotoxicity observed in some individuals. 1 This suggests that there are no unique tumor markers or antigens expressed only on “dispensable” tissue, but rather a collection of proteins with extracellular domains that are expressed to varying degrees primarily on tumors and less so on healthy tissues. 2 Several strategies have been put forward to focus CAR T cells on the tumor while paying less attention to healthy tissue. In one report, pre-treatment with CAIX mAb blocks the access of engineered T cells to CAIX expressed in bile duct epithelial cells, reducing on-target, off-tumor toxicity of CAIX CAR T cells. 3 In another strategy, an antagonistic receptor system, inhibitory CARs (iCARs), were engineered by replacing the cytoplasmic signaling domains with inhibitory signaling chains of the negative regulators of T cell activation, PD-1 or CTLA-4. In a preclinical study, iCAR allows T cells to discriminate the target antigen from the bystander cells and limit off-tumor cytokine secretion and cytotoxicity. 4 While these approaches have promise, they try to limit the activity of a fully competent CAR T cell, which may prove challenging to do on a long-term basis. The synNotch receptor, on the other hand, was developed to only allow expression of a fully functional CAR construct under the right environmental cues. Here, the extracellular Notch domain was replaced by sensor module (eg, ScFv) and the intracellular domain tethers a transcriptional regulator. Upon engagement of target antigen with the synNotch receptor, an orthogonal transcription factor (eg, TetR-VP64 or Gal4-VP64) is cleaved from cytoplasmic tail in an ADAM and γ-secretase dependent manner and this transcription factor drives the expression of the functional CAR construct. 5 In the original application of the synNotch receptor, T cells were engineered to express the CAR only when another molecule was present. In this way, a tumor could be defined as tissue that