The TNF/TNFR2 signaling pathway is a key regulatory factor in endothelial progenitor cell immunosuppressive effect.
- 作者列表："Naserian S","Abdelgawad ME","Afshar Bakshloo M","Ha G","Arouche N","Cohen JL","Salomon BL","Uzan G
BACKGROUND:Endothelial progenitor cells (EPCs) are non-differentiated endothelial cells (ECs) present in blood circulation that are involved in neo-vascularization and correction of damaged endothelial sites. Since EPCs from patients with vascular disorders are impaired and inefficient, allogenic sources from adult or cord blood are considered as good alternatives. However, due to the reaction of immune system against allogenic cells which usually lead to their elimination, we focused on the exact role of EPCs on immune cells, particularly, T cells which are the most important cells applied in immune rejection. TNFα is one of the main activators of EPCs that recognizes two distinct receptors. TNFR1 is expressed ubiquitously and its interaction with TNFα leads to differentiation and apoptosis, whereas, TNFR2 is expressed predominantly on ECs, immune cells and neural cells and is involved in cell survival and proliferation. Interestingly, it has been shown that different immunosuppressive cells express TNFR2 and this is directly related to their immunosuppressive efficiency. However, little is known about immunological profile and function of TNFR2 in EPCs. METHODS:Using different in-vitro combinations, we performed co-cultures of ECs and T cells to investigate the immunological effect of EPCs on T cells. We interrupted in the TNFα/TNFR2 axis either by blocking the receptor using TNFR2 antagonist or blocking the ligand using T cells derived from TNFα KO mice. RESULTS:We demonstrated that EPCs are able to suppress T cell proliferation and modulate them towards less pro-inflammatory and active phenotypes. Moreover, we showed that TNFα/TNFR2 immune-checkpoint pathway is critical in EPC immunomodulatory effect. CONCLUSIONS:Our results reveal for the first time a mechanism that EPCs use to suppress immune cells, therefore, enabling them to form new immunosuppressive vessels. Furthermore, we have shown the importance of TNFα/TNFR2 axis in EPCs as an immune checkpoint pathway. We believe that targeting TNFR2 is especially crucial in cancer immune therapy since it controls two crucial aspects of tumor microenvironment: 1) Immunosuppression and 2) Angiogenesis. Video Abstract. (MP4 46355 kb).
背景: 内皮祖细胞 (EPCs) 是存在于血液循环中的非分化内皮细胞 (ECs)，参与新血管化和修复受损的内皮部位。由于血管疾病患者的 EPCs 受损且效率低下，来自成人或脐带血的同种异体来源被认为是良好的替代来源。然而，由于免疫系统对同种异体细胞的反应通常导致它们的消除，我们关注了 EPCs 对免疫细胞的确切作用，特别是,T 细胞是免疫排斥反应中最重要的细胞。Tnf α 是 EPCs 的主要激活剂之一，可识别两种不同的受体。TNFR1 广泛表达，与 tnf α 相互作用导致分化和凋亡，而 TNFR2 主要表达在 ECs 、免疫细胞和神经细胞上，参与细胞存活和增殖。有趣的是，已经表明不同的免疫抑制细胞表达 TNFR2，这与其免疫抑制效率直接相关。然而，TNFR2 在 EPCs 中的免疫学特征和功能知之甚少。 方法: 采用不同的体外组合，对 ECs 和 T 细胞进行共培养，研究 EPCs 对 T 细胞的免疫作用。我们通过使用 TNFR2 拮抗剂阻断受体或使用 tnf α KO 小鼠来源的 T 细胞阻断配体来中断 tnf α/TNFR2 轴。 结果: 我们证明 EPCs 能够抑制 T 细胞增殖，并将其调节至较少的促炎和活性表型。此外，我们发现 tnf α/TNFR2 免疫检查点通路在 EPC 免疫调节作用中至关重要。 结论: 我们的结果首次揭示了 EPCs 用来抑制免疫细胞的机制，因此，使它们能够形成新的免疫抑制血管。此外，我们已经证明了 tnf α/TNFR2 轴在 EPCs 中作为免疫检查点通路的重要性。我们认为靶向 TNFR2 在癌症免疫治疗中尤其关键，因为它控制了肿瘤微环境的两个关键方面: 1) 免疫抑制和 2) 血管生成。视频摘要。(MP4 46355 kb)。
METHODS::Macrophages (MΦ) play a critical role in tumor growth, immunosuppression and inhibition of adaptive immune responses in cancer. Hence, targeting signaling pathways in MΦs that promote tumor immunosuppression will provide therapeutic benefit. PI3Kγ has been recently established by our group and others as a novel immuno-oncology target. Herein, we report that a macrophage Syk-PI3K axis drives polarization of immunosuppressive MΦs which establish an immunosuppressive tumor microenvironment in in vivo syngeneic tumor models. Genetic or pharmacological inhibition of Syk and/or PI3Kγ in MΦs promotes a pro-inflammatory MΦphenotype, restores CD8+ T cell activity, destabilizes HIF under hypoxia, and stimulates an antitumor immune response. Assay for Transposase-accessible Chromatin using Sequencing (ATAC-seq) analyses on the bone marrow derived macrophages (BMDMs) show that inhibition of Syk kinase promotes activation and binding of NF-κB motif in SykMC-KO BMDMs, thus stimulating immunostimulatory transcriptional programming in MΦs to suppress tumor growth. Finally, we have developed in silico the "first in class" dual Syk/PI3K inhibitor, SRX3207, for the combinatorial inhibition of Syk and PI3K in one small molecule. This chemotype demonstrates efficacy in multiple tumor models and represents a novel combinatorial approach to activate antitumor immunity.
METHODS::Dysfunction of invariant natural killer T (iNKT) cells in tumor microenvironment hinders their anti-tumor efficacy, and the underlying mechanisms remain unclear. Here we report that iNKT cells increase lipid biosynthesis after activation, and that is promoted by PPARγ and PLZF synergically through enhancing transcription of Srebf1. Among those lipids, cholesterol is required for the optimal IFN-γ production from iNKT cells. Lactic acid in tumor microenvironment reduces expression of PPARγ in intratumoral iNKT cells and consequently diminishes their cholesterol synthesis and IFN-γ production. Importantly, PPARγ agonist pioglitazone, a thiazolidinedione drug for type 2 diabetes, successfully restores IFN-γ production in tumor-infiltrating iNKT cells from both human patients and mouse models. Combination of pioglitazone and alpha-galactosylceramide treatments significantly enhances iNKT cell-mediated anti-tumor immune responses and prolongs survival of tumor-bearing mice. Our studies provide a strategy to augment the anti-tumor efficacy of iNKT cell-based immunotherapies via promoting their lipid biosynthesis.
METHODS::Near-infrared photoimmunotherapy (NIR-PIT) is a newly developed and selective cancer treatment that induces necrotic and immunogenic cell death and utilizes a monoclonal antibody conjugated to a photo-absorber dye, IR700DX, activated by NIR light. Although CD44 is surface cancer marker associated with drug resistance, anti-CD44-IR700 NIR-PIT results in inhibited cell growth and prolonged survival in multiple tumor types. Meanwhile, anti-CD25-IR700-targeted NIR-PIT has been reported to achieve selective and local depletion of FOXP3+CD25+CD4+ regulatory T cells (Tregs), which are primary immunosuppressive cells in the tumor microenvironment (TME), resulting in activation of local antitumor immunity. Combined NIR-PIT with CD44- and CD25-targeted agents has the potential to directly eliminate tumor cells and also amplify the immune response by removing FOXP3+CD25+CD4+ Tregs from the TME. We investigated the difference in therapeutic effects of CD44-targeted NIR-PIT alone, CD25-targeted NIR-PIT alone, and the combination of CD44- and CD25-targeted NIR-PIT in several syngeneic tumor models, including MC38-luc, LL/2, and MOC1. The combined NIR-PIT showed significant tumor growth inhibition and prolonged survival compared with CD44-targeted NIR-PIT alone in all tumor models and showed prolonged survival compared with CD25-targeted NIR-PIT alone in MC38-luc and LL/2 tumors. Combined CD44/CD25 NIR-PIT also resulted in some complete remissions, whereas this was not achieved with either type of NIR-PIT alone. Therefore, combined NIR-PIT simultaneously targeting cancer antigens and immunosuppressive cells in the TME may be more effective than either type of NIR-PIT alone and may have potential to induce prolonged immune responses in treated tumors.