HDAC2对巨噬细胞极化调控机制及其在宫颈癌免疫逃逸中的作用

The macrophage is one of important inflammatory cells in the tumor microenvironment. Macrophages can be divided into type I (M1) and type II macrophages (M2) according to the different activation pathways and different functions. M1 macrophages can activate Th1 cells and promote anti-tumor immune response; M2 macrophages mostly promote tumor growth and induce immune escape. However, the epigenetic mechanisms of regulation of macrophage cell phenotypic are still not very clear. In our previous study, we found that the expression of HDAC2, one of HDAC I class family, was up-regulated or down-regulated when macrophages were induced to the M1 or M2 respectively. Knockdown specific histone deacetylase (HDAC2) can inhibit macrophages to the M1-type polarization, down-regulated expression of M1 macrophage related genes. These results suggest that HDAC2 plays vital role in the regulation of macrophage polarization. The project will further reveal the molecular mechanisms and signaling pathways of HDAC2 regulation of macrophage polarization using ChIP, Co-IP, gene or protein chips and other techniques. Furthermore, we will clarify the role of HDAC2 in macrophages induced tumor immune escape in mouse models of cervical cancer and human cervical cancer specimens. These results will provide a new strategy and the theoretical basis for improving cervical cancer immunotherapy.

巨噬细胞是肿瘤微环境中重要炎症细胞。根据活化途径不同和功能不同, 可分为为I 型 ( M1) 和II型巨噬细胞( M2) 。M1型巨噬细胞能活化Th1细胞，促进抗肿瘤免疫应答；M2型巨噬细胞大都促进肿瘤生长，诱导免疫逃逸。M1-M2表型转化即为极化（polarization）。我们前期研究发现，巨噬细胞在诱导向M1或M2转换时组蛋白去乙酰化酶（HDACs）家族中的HDAC2分别出现明显上调或下调。敲除HDAC2可以抑制巨噬细胞向M1型极化，下调表达M1型巨噬细胞相关基因。这些结果提示，HDAC2在调控巨噬细胞极化过程中作用关键。本项目将运用ChIP-qPCR，Co-IP，基因芯片等技术进一步揭示HDAC2调控巨噬细胞极化的分子机制和信号通路，同时在小鼠宫颈癌模型中结合人宫颈癌肿瘤标本阐明HDAC2对巨噬细胞极化调控在肿瘤免疫逃逸中的作用及功能，为宫颈癌免疫治疗提供新的策略和奠定理论基础。

研究背景：宫颈癌是女性高发性肿瘤，位居女性肿瘤发病率的第三位。宫颈癌是由HPV感染引起。HPV的感染除了引起宫颈上皮细胞基因突变而产生恶变外，长期炎症反应所形成的肿瘤微环境对宫颈癌的发生发展同样起着重要作用。本研究着重研究肿瘤相关巨噬细胞这一肿瘤微环境中重要的免疫细胞的表观遗传改变对于巨噬细胞极化以及宫颈癌发生发展的影响。本研究主要研究内容如下：1、明确HDAC2对巨噬细胞极化调控的关键作用及对T 辅助细胞活化效应；2、阐明参与HDAC2调节巨噬细胞极化过程的关键信号分子以及相关机制；3、在小鼠宫颈癌模型中验证HDAC2对巨噬细胞极化的调控在肿瘤免疫逃逸中作用；4、宫颈癌患者标本中验证HDAC2在巨噬细胞中的表达量与肿瘤分期、分级以及预后的关系。实验结果：首先证实肿瘤微环境抑制肿瘤相关巨噬细胞HDAC2的表达，促进巨噬细胞向M2方向极化，从而抑制CD8+T细胞的抗肿瘤应答。接着我们阐明了HDAC2通过调节转录因子c-jun的表达来干预M2相关基因表达。在小鼠皮下接种肿瘤模型中，我们进一步证实HDAC2的缺失加剧巨噬细胞向M2偏移，促进肿瘤生长。最后我们拟将收集宫颈癌病人标本通过免疫组化和免疫荧光揭示HDAC2在肿瘤相关巨噬细胞中的表达和肿瘤发生发展以及转归的关系。本研究成果可为通过改善肿瘤微环境提高肿瘤免疫治疗疗效提供理论和实验基础。