膀胱癌肿瘤干细胞源性外泌体促进巨噬细胞M2型极化并上调IDO1介导免疫逃逸的机制研究

Exosomes is one of the key factors affecting the effectiveness of tumor immunotherapy and play an important role in the immune regulation of tumors. In the previous study, we prepared a bladder cancer stem cell vaccine, and the results showed that the vaccine can induce a specific immune response to kill cancer stem cells. However, the bladder cancer stem cell-derived exosomes mediated immune escape by promoting M2 macrophage polarization and up-regulating IDO1 expression, which limited the efficacy of tumor vaccines. Through bioinformatics analysis and sequencing techniques, we found that miRNA-146a and lncRNA-MALAT1 may be the key molecules that mediate this phenomena. Therefore, we hypothesize that bladder cancer stem cells may escape the attack of immune system by releasing exosomes carrying miRNA-146a or lncRNA-MALAT1, which promotes M2 polarization of macrophages and up-regulate IDO1 expression through related signaling pathways. Therefore, this study will conduct a series of cell experiments and animal experiments to elucidate the molecular mechanism by which tumor exosomes mediates macrophage M2 polarization and IDO1 up-regulation. It is likely to discover a new tumor immune escape mechanism and provide some new ideas for tumor prevention and treatment.

外泌体在肿瘤的免疫调控中发挥重要作用，是影响肿瘤的免疫治疗的关键因素之一。在前期研究中，我们制备了膀胱癌肿瘤干细胞疫苗，通过研究发现：该疫苗能诱导机体产生杀伤肿瘤干细胞的特异性免疫反应，但同时也发现：肿瘤微环境中存在肿瘤外泌体介导的巨噬细胞M2型极化以及IDO1表达上调，进而限制了肿瘤疫苗的疗效。通过生物信息学分析及测序技术，我们发现：miRNA-146a和lncRNA-MALAT1可能是介导上述现象的关键分子。因此，我们推测：膀胱癌肿瘤干细胞可能是通过释放携带有miRNA-146a或lncRNA-MALAT1的外泌体，经过相关的信号途径促进巨噬细胞的M2极化并同时上调IDO1的表达，进而介导肿瘤的免疫逃逸。因此，本课题拟通过一系列的细胞实验和动物实验，阐明肿瘤外泌体介导巨噬细胞M2型极化和上调IDO1的分子机制，将很可能发现新的肿瘤免疫逃逸机制，为肿瘤的预防和治疗提供新的思路。

研究背景和目的：.膀胱肿瘤干细胞来源的外来体通过促进巨噬细胞M2型极化并上调吲哚胺-2,3-双加氧酶1（IDO1）表达来介导免疫逃逸。然而，相关的分子机制尚不清楚。本研究的目的是阐明膀胱肿瘤干细胞来源的外来体通过促进巨噬细胞M2型极化并上调IDO1表达来介导免疫逃逸的分子机制。.研究内容和结果：.膀胱肿瘤干细胞来源的外泌体能促进M2型巨噬细胞标志物（CD163和CD206）和IDO1的表达，并促进了M2型巨噬细胞相关细胞因子水平（Arg-1，IL-10，ym-1，mrc-1）的分泌。膀胱肿瘤干细胞来源的外泌体中高表达miR-146a。体外和体内实验结果证实：miR-146a或外泌体miR-146a通过TRAF6 / STAT3信号通路诱导巨噬细胞M2极化并上调IDO1表达。膀胱肿瘤干细胞来源的外泌体miR-146a通过促进巨噬细胞M2型极化并上调IDO1表达明显抑制CD8+ T细胞的增殖功能。敲除miR-146a则显著抑制M2巨噬细胞的极化，并下调IDO1的表达。.结论：.本研究结果表明，膀胱肿瘤干细胞来源的外泌体miR-146a通过TRAF6/STAT3信号通路诱导M2巨噬细胞极化并上调IDO1表达。该研究为膀胱癌的免疫治疗提供了新思路。