外泌体选择性运载miR-155调控Tfh细胞介导CLL微环境免疫失衡的机制研究

Microenvironmental immunodissonance plays a key role during occurrence and development of chronic lymphocytic leukemia(CLL) and remains the difficult bit waiting to be resolved at present. The T follicular helper(Tfh) cells in CLL patients are elevated and dysfunctional, the machanisms of which still remain unclear. Our previous work revealed the relevance of the increase of Tfh cells and inferior outcome of the disease, and we found that the expression of miR-155, a key microRNA regulating the differentiation of Tfh cells, was increased in the tumor-derived exosomes (Exo) from patients of progressive stage. Therefore, we presume that CLL cells might affect the function of Tfh cells by delivering exosomal miR-155, thus promoting disease progression. Based on the previous work and taking primary leukemia cells, a mouse model and cell lines as research objects, we are planning to further clarify: ①the relevance of overexpression of miR-155 in Exo with disease progression and Tfh cell dysfunction; ②whether CLL cells impact Tfh cells through Exo; ③ whether the impact of CLL-dirived Exo on Tfh cells is caused by miR-155 targeting FOS. The results will further illuminate the communication mechanisms between CLL cells and immune cells in the microenvironment and provide new methods and laboratory evidence to improve microenvironmental immunity in CLL.

微环境免疫失衡在慢性淋巴细胞白血病（CLL）发生发展过程中起关键作用，也是治疗难点。CLL患者存在滤泡辅助性T细胞（Tfh）数量增多及功能异常，但机制尚不清楚。我们前期工作发现Tfh细胞比例升高与CLL疾病预后不良相关，同时进展期患者肿瘤外泌体（Exo）中miR-155表达升高，而miR-155是对Tfh细胞分化起调控作用的关键microRNA。由此我们推测CLL细胞可能通过Exo传递miR-155影响Tfh细胞功能从而促进疾病进展。本项目拟在前期工作的基础上，以患者原代细胞、小鼠模型及细胞系为研究对象，进一步明确：①Exo高表达miR-155与CLL疾病进展及Tfh功能异常的相关性；②CLL细胞是否可通过Exo作用于Tfh细胞；③该影响是否通过传递miR-155作用于FOS基因所致。项目结果将进一步阐明CLL细胞与微环境免疫细胞的沟通机制，为改善CLL微环境免疫提供新的思路和实验室依据。

慢性淋巴细胞性白血病（CLL）是西方国家成年人群中最常见的白血病类型，其特点是外周血液中成熟的CD5阳性B淋巴细胞的异常扩增。在我国，CLL的发病率相对较低，但随着诊断水平的提升，已呈逐年上升的趋势。微环境免疫失衡在慢性淋巴细胞白血病（CLL）发生发展过程中起关键作用，也是治疗难点。我们通过检测临床患者血液样本发现CLL患者存在滤泡辅助性T细胞（Tfh）数量增多及功能异常，且Tfh细胞比例升高与CLL疾病预后不良相关，同时患者肿瘤细胞外泌体（Exo）中miR-155表达显著升高。我们进一步通过体外实验验证了CLL细胞通过外泌体携带miR-155促进Tfh细胞分化，并且经外泌体诱导分化后的Tfh细胞可以显著促进CLL细胞增殖。除此之外，我们发现1,25（OH）2D3（维生素D）通过抑制CLL细胞miR-155表达来阻断外泌体miR155对Tfh的促分化作用。本研究首次阐明了CLL细胞通过外泌体携带miR-155的方式介导微环境Tfh比例失衡的机制，并且发现维生素D可以有效阻断这一进程。本研究为CLL免疫失衡机制提供了有力的实验依据，并为CLL治疗策略提供了新的思路。