PAX5突变诱导B细胞急淋非T细胞炎症性免疫逃逸？

PAX5 mutation is an important risk factor for acute lymphoblastic leukemia (ALL), and is an independent poor prognosis for children ALL. One of the mechanisms of PAX5 mutations inducing B cell ALL is that PAX5 mutations lead to tumor immune escape. We used the gene editing technique to construct PAX5 haploinsufficiency cell line. Through the microarray analysis of PAX5 haploinsufficiency cells, we found that PAX5 haploinsufficiency resulted in abnormal expression of various genes involved in the immune response, which could induce the non T cell inflamed immune escape by affecting the activation and recruitment of T cells. Recent studies have shown that PI3K-AKT pathway is an important mechanism for the non T cell inflamed immune escape, meanwhile we found that PAX5 haploinsufficiency led to gene expression changes in PI3K-AKT pathway-related genes. Therefore, we believe that PAX5 haploinsufficiency leads to non-T cell-inflamed immune escape. We used mouse PAX5 haploinsufficiency B-cell leukemia model to confirm that PAX5 haploinsufficiency lead to non-T cell inflamed immune escape, and to clarify its specific mechanism by NanoString in mice and patients of PAX5 mutation ALL. This study will provide the theoretical foundation for the immunotherapy in B-ALL with PAX5 mutant.

PAX5 突变是B 急淋的重要发病因素，也是儿童B急淋独立不良预后因素。PAX5突变诱发B急淋的机制之一在于PAX5突变导致肿瘤免疫逃逸。我们利用基因组编辑技术构建了PAX5单倍体缺失的B细胞肿瘤细胞株，表达谱芯片分析结果提示PAX5单倍体缺失可能导致非T细胞炎症性 (non T cell inflamed)的免疫逃逸。PAX5突变可能通过PI3K-AKT通路依赖的方式导致非T细胞炎症性免疫逃逸。我们构建PAX5单倍体缺失小鼠B细胞白血病模型，采用包括NanoString芯片的多种检测技术，通过体内外实验及临床PAX5突变B急淋标本检测，证实PAX5单倍体缺失诱导非T细胞炎症性免疫逃逸，并阐明具体机制，探讨逆转PAX5突变诱导免疫逃逸的可行性。本项目的意义在于：阐明PAX5突变导致B急淋发病及复发的免疫逃逸机制，发现能逆转PAX5突变B急淋免疫逃逸的新方法，为B急淋免疫治疗提供新的可能。

PAX5突变是B细胞急淋的高发突变，参与B细胞急淋的不良预后。PAX5突变诱导的B细胞肿瘤免疫逃逸机制目前尚不清楚。我们建立PAX5单倍体缺失模型来研究PAX5突变诱导B细胞肿瘤免疫逃逸的机制。采用基因编辑技术成功建立PAX5突变的A20细胞株，并采用PAX5突变的A20细胞株建立B细胞肿瘤小鼠模型。观察到PAX5突变B细胞肿瘤生长明显超过PAX5野生型肿瘤。采用RT-PCR和免疫组化方法证实，PAX5突变通过诱导肿瘤微环境中趋化因子Ccl2、Ccl4、Cxcl9和Cxcl10水平下降，诱导肿瘤微环境中CD8+ T细胞数量下降，导致非T细胞炎症性免疫逃逸。同时研究发现在肿瘤微环境中，PAX5突变的B细胞肿瘤诱导CD8+效应T细胞TIM3, NR4A1 和 BATF水平降低。同时PAX5突变也导致CD8+ 效应T细胞分泌INF-ɤ水平下降。说明PAX5突变导致CD8+效应T细胞耗竭和失功能。研究说明PAX5不仅诱导非T细胞炎症性免疫逃逸，而且诱导CD8+效应T细胞耗竭和失功能。