Disparate suppression of naive effector and memory T cells in tumor-bearing hosts

描述（由申请人提供）：尽管许多团体持续努力开发用于治疗癌症的免疫方法，但到目前为止，治疗反应令人失望。这次失败的原因尚不清楚。因此，在当前的研究中，我们建议通过改变TGF-b易感性来研究t细胞成熟阶段在决定t细胞对肿瘤诱导抑制的易感性中的作用。记忆和效应CD8+ T细胞在功能上比初始细胞反应更灵敏。因此，我们假设记忆T细胞和效应T细胞比初始细胞更不容易受到肿瘤诱导的抑制。矛盾的是，我们发现效应CD8+ T细胞比初始细胞更容易受到肿瘤诱导的抑制（90% vs 30%）。我们的数据表明，体外活化效应CD8+ T细胞的过继转移可能是无效的，因为CD8+ T细胞对肿瘤诱导抑制的易感性增加。关于这种不同效应的机制，我们发现TGF-b是抑制的关键分子介质，TGF-b信号传导的转录调节因子（Smad4和TGF-bRII）的表达与t细胞状态和对抑制的易感性相关。基于这些观察结果，我们提出以下假设：CD8+ T细胞成熟状态（初始、效应和记忆）决定了对肿瘤诱导抑制的易感性，由于对TGF-b的反应性增加，效应T细胞和记忆T细胞比初始T细胞更容易受到抑制。为了评估抗原特异性CD8+ T细胞反应，我们将使用来自转基因小鼠的CD8+ T细胞，表达CD8+ TCR对抗gp100/pmel（一种由正常黑色素细胞和黑色素瘤细胞自然表达的自身抗原）和非自身抗原鸡卵白蛋白（OT-I）。1)我们将在体外研究幼稚型、效应型和记忆型CD8+ T细胞对TGF-b的易感性，以及TGF-bRII和Smads的表达是否与抑制易感性相关。2)我们将评估肿瘤播散性疾病（早期和已建立）对初始、效应和记忆CD8+ T细胞的体内抑制作用，以及消耗抑制细胞或阻断TGF-b对初始、效应和记忆CD8+ T细胞反应的影响。3)我们将研究在CD8+ T细胞体内干扰TGF-b信号是否能均匀地拯救幼稚的、效应的和记忆的TCR转基因CD8+ T细胞免受肿瘤诱导的抑制。

DESCRIPTION (provided by applicant): Despite the sustained efforts of numerous groups to develop immune approaches for the treatment of cancer, thus far, the therapeutic responses have been disappointing. The reasons for this failure remain unknown. Thus, in the current study we propose to study the role of T-cell maturation stage in determining T-cell susceptibility to tumor-induced suppression by alterations in TGF-b susceptibility. Memory and effector CD8+ T cells are functionally more responsive than naive cells. Thus, we hypothesized that memory and effector T cells were less susceptible to tumor-induced suppression than naive cells. Paradoxically, we found that effector CD8+ T cells were considerably more susceptible to tumor-induced suppression than naive cells (90% vs. 30%). Our data suggest that adoptive transfer of in vitro activated effector CD8+ T cells may be ineffective due to increased CD8+ T-cell susceptibility to tumor-induced suppression. Regarding the mechanisms responsible for this disparate effect, we found that TGF-b was a key molecular mediator of suppression, and expression of transcriptional regulators of TGF-b signaling (Smad4 and TGF-bRII) correlated with T-cell status and susceptibility to suppression. Based on these observations, we propose the following hypothesis: CD8+ T-cell maturation status (naive, effector and memory) determines susceptibility to tumor-induced suppression, with effector and memory T cells being more susceptible to suppression than naive T cells, due to increased responsiveness to TGF-b. In order to evaluate antigen specific CD8+ T-cell responses, we will use CD8+ T cells from transgenic mice expressing a CD8+ TCR against gp100/pmel (a self antigen naturally expressed by normal melanocytes and melanoma cells) and a non-self antigen, chicken ovalbumin (OT-I). 1) We will examine the susceptibility of naive, effector and memory CD8+ T cells to TGF-b in vitro, and whether expression of TGF-bRII and Smads correlates with susceptibility to suppression. 2) We will evaluate the in vivo suppressive effect of tumor disseminated disease (early and established) on naive, effector and memory CD8+ T cells, and the effect of depleting suppressor cells or blocking TGF-b on naive, effector and memory CD8+ T-cell responses. 3) We will study whether interfering with TGF-b signaling in vivo in CD8+ T cells evenly rescues naive, effector and memory TCR transgenic CD8+ T cells from tumor-induced suppression. Narrative The results of T-cell based immune therapeutic approaches against cancer based on adoptive cell transfer and vaccination, thus far, have been disappointing for reasons that remain unknown. Thus, in the current study we propose to study the role of T-cell maturation stage (naive, effector and memory) in determining T-cell susceptibility to tumor-induced suppression by alterations in TGF-b susceptibility.