Department of Microbiology and Immunology, The Sahlgrenska Academy at The University of Gothenburg, Göteborg, Sweden.
Expert Rev Gastroenterol Hepatol. 2011 Aug;5(4):489-501. doi: 10.1586/egh.11.44.
Regulatory T cells (Tregs) have the ability to suppress the activity of most other lymphoid cells, as well as dendritic cells through cell-cell contact-dependent mechanisms, which have not yet been fully defined. Tregs are a key component of a functional immune system and Treg deficiency is associated with severe autoimmunity and allergies. However, Tregs specific for tumor-associated antigens are present in cancer patients and Tregs accumulate in many types of solid tumors, where they probably act to promote tumor escape from cytotoxic immune responses. Indeed, some studies even show a negative correlation between Treg infiltration and survival of the patient. Several studies indicate an active recruitment of Tregs to the tumor site and the mechanisms of Treg accumulation are starting to be better understood as a result of more detailed analysis of their adhesion molecule and chemokine receptor expression. In addition, in gastrointestinal tumors there is an increase in tumor-associated Tregs, but intriguingly, Treg infiltration into colorectal adenocarcinomas is associated with improved prognosis. In this article, we will review the proposed mechanisms of immune suppression by tumor-associated Tregs, how the tumor microenvironment favors immune evasion and Treg induction, the tumor-homing mechanisms of Tregs and how Tregs affect progression of gastric and colorectal tumors.
调节性 T 细胞（Tregs）具有通过细胞间接触依赖机制抑制大多数其他淋巴细胞和树突状细胞活性的能力，但尚未完全定义。Tregs 是功能性免疫系统的关键组成部分，Treg 缺乏与严重的自身免疫和过敏有关。然而，肿瘤相关抗原特异性的 Tregs 存在于癌症患者中，并且 Tregs 在许多类型的实体瘤中积聚，在这些肿瘤中，它们可能作用于促进肿瘤逃避细胞毒性免疫反应。事实上，一些研究甚至表明 Treg 浸润与患者的生存呈负相关。几项研究表明 Tregs 被积极招募到肿瘤部位，并且由于对其粘附分子和趋化因子受体表达的更详细分析，Treg 积聚的机制开始得到更好的理解。此外，在胃肠道肿瘤中，肿瘤相关的 Tregs 增加，但有趣的是，Treg 浸润结直肠腺癌与改善的预后相关。在本文中，我们将综述肿瘤相关 Tregs 抑制免疫的可能机制、肿瘤微环境如何有利于免疫逃逸和 Treg 诱导、Tregs 的肿瘤归巢机制以及 Tregs 如何影响胃和结直肠肿瘤的进展。
