Regulation of T cell Functions by the Breast Cancer Microenvironment

为什么肿瘤反应性T细胞不能消灭肿瘤？虽然在引流的淋巴结内启动往往是次优的，但更常见的是，免疫反应在肿瘤本身受到阻碍。这可能是由于对肿瘤的免疫监视(耐受性)的保护，或对局部引流淋巴结的重新启动和反馈不足(一个中断的反馈环路)。 基于一组初步数据，我们假设，肿瘤微环境中的APC亚群通过与T细胞直接相互作用、通过它们对相互作用的反应不成熟以及通过与调节性T细胞的合作来保护肿瘤免受CTL的伤害。我们认为，微环境建立了这些细胞的武器库，并在“灭活灶”收集免疫系统，防止启动的CTL对肿瘤进行稳定和有效的监视。通过同时阻止I细胞看到肿瘤，并在那里次佳地激活它们，这些细胞可能有效地 中和回应。 我们建议在一种新的人类乳腺癌模型系统中研究这一点，我们已经培育并明确描述了这一难于理解的问题的PyMTCherry-OVA小鼠。该模型允许通过本征荧光直接显示肿瘤和肿瘤样本APC。这一点意义重大，因为我们能够研究T细胞在接触这些不同类型的细胞时发生了什么，特别是通过双光子显微镜。这也具有重要意义，因为我们还能够使用多色流式细胞术、微阵列和体外分析来对这一非常重要的APC群体进行表型，并提供有关APC和I细胞群体共同发展导致肿瘤接受性的关键数据。 应该指出的是，所提出的研究是第一批可以在非异位肿瘤模型中实现的研究之一，该模型在许多重要方面与人类乳腺癌非常相似。我们模型的自发病理学也很重要，因为异位肿瘤不太可能通过原发肿瘤忠实地复制免疫逃避的重要方面，包括微环境。 因此，对这一系统的研究更有可能概括出人类疾病的特征和免疫逃避的“正常”建立。这些实验的结果将揭示随着时间的推移，I细胞在从增殖发展到已建立的癌症过程中的动态变化。它们还将明确揭示调节性I细胞与局部I细胞反应的细胞之间的相互作用。最后，重要的是，它们将揭示以前无法接触到的细胞群体，这些细胞群体可能保护肿瘤免受免疫反应的影响，从而允许肿瘤生长和转移。

Why don't tumor-reactive T cells eliminate tumors? Although priming in the draining lymph node is often suboptimal, more frequently, the immune response is stymied at the tumor itself. This may be as a result of a protection of the tumor from immune surveillance (tolerance) or inadequate repriming and feedback to the local draining lymph node (an interrupted feedback loop). Based on a panel of preliminary data, we hypothesize that a subpopulation of APCs in the tumor microenvironment protect the tumor from CTLs by direct interaction with the T cells, by their failure to mature in response to the interaction, and by cooperation with regulatory T cells. We believe the microenvironment builds an arsenal of these cells and collects the immune system at 'inactivating foci' that prevent stable and effective surveillance of the tumor by primed CTLs. By simultaneously preventing the I cells from seeing the tumor and suboptimally activating them there, these cells may effectively neutralize the response. We propose to study this in a new model system of human breast cancer, the PyMTCherry-OVA mouse that we have produced and characterized expressly to address this poorly accessible problem. The model allows direct visualization of the tumor AND the tumor-sampling APCs via intrinsic fluorescence. This is significant as we are able to study what is happening to the T cell as it contacts these distinct cell types, specifically via 2-photon microscopy. It is also significant because we are also able to phenotype this very important APC population using multicolor flow cytometry, microarray, and in vitro assays and provide key data about the co-development of APC and I cell population that results in tumor acceptance. It should be noted that the studies proposed are amongst the first of their kind that will be achievable in a non-ectopic tumor model that very closely resemble human breast cancer in many important ways. The spontaneous eteliology of our model is also important, as there are many reasons that ectopic tumors are unlikely to faithfully replicate important aspects of immune-evasion, including the microenvironment, by a primary tumor. Thus, studies in this system are much more likely to recapitulate the features of human disease and the 'normal' establishment of immune evasion. The results of these experiments are going to reveal the dynamics of I cells over time in the developing hyperplasia through to established carcinomas. They will also definitely reveal the interaction of regulatory I cells with cells of the local I cell response. Finally, and not insignificantly, they will shed considerable light upon a previously inaccessible cell population which may protect the tumor from the immune response and thus permit tumor growth and metastasis.