The role of immunosuppressive cells in metastasis

免疫抑制细胞在转移中的作用

• 批准号: 7963976
• 负责人: Arya Biragyn
• 金额: $ 17.41万
• 依托单位: NATIONAL INSTITUTE ON AGING
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/7963976
• 关键词: Affect; Autoantigens; B-Lymphocytes; Binding; Biological; Brain; Breast Cancer Cell; CCL17 gene; CD8B1 gene; Carcinoma; Cell Count; Cell Death Induction; Cells; Cytotoxic T-Lymphocytes; Disease; Disease Outcome; Distant; Galectin 1; Growth; Hand; Heterophile Antigens; Housing; Human; Immune; Immune response; Immunosuppressive Agents; Inbred BALB C Mice; Lead; Lectin; Ligands; Liver; Lung; Maintenance; Mammary gland; Mediating; Memory; Mus; Myelogenous; NK Cell Activation; Natural Killer Cells; Neoplasm Metastasis; Outcome; Patients; Peripheral; Play; Primary Neoplasm; Process; Production; Progressive Disease; Proteins; Publishing; Recruitment Activity; Regulation; Reporting; Rest; Role; Signal Transduction; Site; Staging; T cell regulation; T-Cell Proliferation; T-Lymphocyte; anergy; beta-galactoside; bone; cancer cell; chemokine; chemokine receptor; combat; cytotoxic; granzyme A; implantation; improved; killings; macrophage; malignant breast neoplasm; neoplastic cell; peripheral blood; prevent; response; tumor

We have found that primary tumor growing at distant site induced production of TARC/CCL17 (a chemokine ligand for CCR4) in lungs. Thus, this is presumably to facilitate recruitment of CCR4+ Tregs which, as we recently reported, play a major role in regulation of T cell responses. Although the existence of CCR4+ breast cancers remained unknown, we have hypothesized that breast cancer also utilizes CCR4 in the lung metastasis. Utilizing in house developed strategies, such as chemotoxin that depletes CCR4+ cells (see AG000444-02), we demonstrated that CCR4 was indeed expressed on a portion of breast cancer cells that metastasize into into inflamed lungs producing TARC and MDC. This is a first report on the use of TARC/MDC-CCR4 axis in the metastatic spread of breast cancer. On the other hand, we also confirmed our second part of the hypothesis that primary tumor-induced production of TARC and MDC was also to recruit CCR4+ Tregs. Indeed, we demonstrate that in the absence of Tregs, the inherent capability of tumors alone to migrate into inflamed lungs was not sufficient to establish lung metastasis. Lung metastasis required an active participation of CCR4+ Tregs. The biological role of Tregs was to infiltrate lungs together with tumor cells to regulate or even kill anti-tumor NK cells. This presumably explains our finding that NK cell counts were significantly reduced in peripheral blood (PB) of both tumor-bearing mice and human patients with an advanced stage IV breast cancer. Thus, strategies that abrogate any part of this process, such as targeted inactivation of CCR4+ cells or direct depletion of Tregs, would be expected to improve the outcome of the disease. This in turn would activate both antitumor innate and adaptive immune responses through activation of NK cells and cytolytic T cells. Indeed, the treatment of tumor -bearing mice with TARC-chemotoxin significantly reduced lung metastasis of 4T1 cells through depletion of Tregs and metastasizing tumors and activating NK cells. The finding has been recently published (Olkhanud et al., 2009). Despite significant efforts, practically very little is known about mechanisms of suppressive activity exerted by Tregs. Recently, we have demonstrated that Tregs in human PBL consisted of at least two functionally distinct subsets, memory-type CCR4+Tregs and nave-type CCR4- Tregs (Baatar et al., 2007). CCR4+ Tregs also regulate resting CD8+ T cell responses without killing them or use of granzymes A and B (as others reported). In contrast, we have found that Tregs regulate T cell proliferation through a cell contact-dependent process involving FasL/Fas signaling. Recently we have found that CCR4+Tregs express and utilize lectin-type proteins, such as beta-galactoside-binding prottein (bGBP). bGBP and its dimeric lectin form Galectin-1 are immunosuppressive proteins expressed by activated immune cells, such as T cells, B cells and macrophages. Interestingly, bGBP actively participated in regulation of CD8+ T cells. It was used by Tregs to regulate TCR signaling of CD8+ T cells without induction of cell death, although bGBP is known to be cytotoxic for activated T cells. The mechanism of this process was in the capacity of bGBP to induce limited (non-processive) TCR signaling in target T cells; as it only activates Zap70, but not downstream molecules, such as ERK, Ras and PI3K. Although non-processive TCR signaling can lead to anergy, bGBP does not induce anergy of CD8+ T cells. In addition, we have found that Tregs utilize bGBP to inhibit PI3K that led in the blockage of Ras/MAPK and ERK. This presumably allows Tregs to transiently prevent activation of CD8+ T cells by self-antigens, while keeping responses to xenogeneic antigens unaffected, indicating the important biological role of bGBP in the maintenance and control of peripheral tolerance (Baatar et al., 2009).

我们发现，远处生长的原发肿瘤会诱导肺部产生 TARC/CCL17（CCR4 的趋化因子配体）。因此，这可能是为了促进 CCR4+ Tregs 的募集，正如我们最近报道的那样，CCR4+ Tregs 在调节 T 细胞反应中发挥着重要作用。尽管 CCR4+ 乳腺癌的存在仍然未知，但我们假设乳腺癌也在肺转移中利用 CCR4。利用内部开发的策略，例如消耗 CCR4+ 细胞的趋化毒素（参见 AG000444-02），我们证明 CCR4 确实在部分乳腺癌细胞上表达，这些乳腺癌细胞转移到发炎的肺部，产生 TARC 和 MDC。这是关于 TARC/MDC-CCR4 轴在乳腺癌转移扩散中的应用的第一份报告。另一方面，我们还证实了假设的第二部分，即原发性肿瘤诱导的 TARC 和 MDC 的产生也是为了招募 CCR4+ Tregs。事实上，我们证明，在没有 Tregs 的情况下，肿瘤本身迁移到发炎肺部的固有能力不足以建立肺转移。肺转移需要CCR4+ Tregs 的积极参与。 Tregs的生物学作用是与肿瘤细胞一起浸润肺部，调节甚至杀死抗肿瘤NK细胞。这大概解释了我们的发现：荷瘤小鼠和患有晚期 IV 期乳腺癌的人类患者的外周血 (PB) 中 NK 细胞计数显着减少。因此，废除该过程任何部分的策略，例如 CCR4+ 细胞的靶向失活或直接耗竭 Tregs，有望改善疾病的结果。这反过来又会通过激活 NK 细胞和溶细胞 T 细胞来激活抗肿瘤先天免疫反应和适应性免疫反应。事实上，用 TARC-趋化毒素治疗荷瘤小鼠可通过消除 Tregs、转移肿瘤和激活 NK 细胞，显着减少 4T1 细胞的肺转移。该发现最近已发表（Olkhanud 等，2009）。 尽管付出了巨大的努力，但实际上人们对 Tregs 的抑制活性机制知之甚少。最近，我们证明人类 PBL 中的 Tregs 由至少两个功能不同的子集组成，即记忆型 CCR4+Treg 和幼稚型 CCR4-Treg（Baatar 等，2007）。 CCR4+ Tregs 还调节静息 CD8+ T 细胞反应，而不杀死它们或使用颗粒酶 A 和 B（如其他人报道的）。相比之下，我们发现 Tregs 通过涉及 FasL/Fas 信号传导的细胞接触依赖性过程来调节 T 细胞增殖。最近我们发现CCR4+Tregs表达并利用凝集素型蛋白，例如β-半乳糖苷结合蛋白(bGBP)。 bGBP 及其二聚体凝集素形式 Galectin-1 是由激活的免疫细胞（例如 T 细胞、B 细胞和巨噬细胞）表达的免疫抑制蛋白。有趣的是，bGBP 积极参与 CD8+ T 细胞的调节。尽管已知 bGBP 对活化的 T 细胞具有细胞毒性，但 Tregs 使用它来调节 CD8+ T 细胞的 TCR 信号传导而不诱导细胞死亡。该过程的机制在于 bGBP 能够在靶 T 细胞中诱导有限（非进行性）TCR 信号传导；因为它只激活 Zap70，而不激活下游分子，例如 ERK、Ras 和 PI3K。尽管非进行性 TCR 信号传导可导致无反应性，但 bGBP 不会诱导 CD8+ T 细胞无反应性。此外，我们发现Tregs利用bGBP抑制PI3K，从而导致Ras/MAPK和ERK的阻断。这可能使得 Tregs 能够暂时阻止自身抗原激活 CD8+ T 细胞，同时保持对异种抗原的反应不受影响，表明 bGBP 在维持和控制外周耐受中的重要生物学作用 (Baatar et al., 2009)。