胃癌微环境中CD40调控髓系来源抑制性细胞（MDSC）生物学功能的作用机制

Myeloid-derived suppressor cells (MDSCs) are potent immune-suppressive cells promoting tumor progression and metastasis. However, the regulatory mechnism MDSC in tumor enviroment remains unclear. CD40 is an important molecule in the regulations of celluar biology including anti-apoptosis, Th subset induction, and cell differentiation of myeloid cells.In previous work,we found that CD40 expression is detectable on gastric carcinoma infiltrating MDSC at a low level. Thus, we hypotheses that CD40 play an important role in apoptosis resistance, Treg induction, and cell differentiation of MDSC in tumor microenviroment of gastric carcinoma. To confirm the above hypotheses, we intend to carry out these following experiments: (1) to study the clincal significance of CD40 expreased on MDSC in gastric carcinoma, and to analysis the association of CD40+MDSC with Treg, apoptotic index of MDSC or number of MDSC in tumor microenviroment of gastric carcinoma; (2) Using CD40 knockout and wildtype mice, to analyze the role of CD40 in regulating MDSC biological functions including treg expansion, MDSC accumulation and differentiation in vitro, and to assess the effect of CD40 on MDSC-mediated immune escape through tumor-bearing mouse model; (3) To analyze the changes of function-associated membrane molecules and signal molecules of MDSC sitmulated with CD40L; in following functional analysis, we will use special inhibitions to confirm the molecular mechanism of CD40 in regulation of MDSC. In summary, we aim to anayze the effect of CD40 on MDSC biology and advance our understanding of the tumor immune evasion mechanism, which may lead to new strategies for treatment of gastric carcinoma.

髓源性抑制细胞（MDSC）在肿瘤免疫逃逸中发挥着重要作用，调控MDSC生物学功能在免疫治疗中具有重要价值，但调控机制尚不清楚。CD40在细胞凋亡、分化以及诱导Th扩增中均发挥重要作用。课题组前期工作发现胃癌微环境中MDSC表达CD40，因此推测CD40在调控胃癌微环境MDSC生物学功能中可能发挥关键作用。鉴此，本项目拟开展以下研究：（1）通过病例研究，分析CD40在胃癌患者MDSC表达的临床意义，并探讨CD40表达与MDSC功能之间的相关性；（2）利用模式动物获得CD40-和CD40+MDSC细胞，体外实验分析CD40信号调控MDSC凋亡、诱导Treg扩增以及向DC分化中的生物学功能；体内实验探讨CD40在MDSC介导的肿瘤免疫逃逸中的作用。（3）利用基因芯片技术，分析CD40激发前后MDSC功能分子变化情况，利用特异性阻滞剂进行体内外干预，分析CD40调控MDSC生物学功能的分子机制。

《胃癌微环境中CD40调控髓系来源抑制性细胞（MDSC）生物学功能的作用机制（81272737）》获得了如下研究进展：.1）CD40在MDSC上动态表达：通过构建荷瘤小鼠模型，较为系统的分析了CD40在肿瘤浸润MDSC上的表达情况，发现随着肿瘤生长，MDSC逐渐聚集，然而CD40呈逐渐降低的趋势，CD40表达水平与MDSC数量成显著负相关。2）CD40信号促进MDSC凋亡：为研究CD40对MDSC的生物学作用，项目组利用CD40激发型抗体体外刺激MDSC，结果发现，与同型对照组相比，CD40信号激发可以显著促进MDSC凋亡。3）发现并鉴定一群CD40+MDSC：CD40-MDSC以环形核、分叶核和多形核幼稚的粒细胞为主；CD40+MDSC多为圆形和椭圆形核，核质比较大，主要是幼稚单核细胞。4）CD40+MDSC促进MDSC聚集；分选CD40+和CD40-两群MDSC，并通过体外基因芯片分析发现一组趋化因子在两者间存在显著差异；趋化迁移实验提示，CD40+MDSC可以通过CXCR5/CXCL13促进MDSC向肿瘤局部迁移，并继而促进胃癌进展。.总之，项目组基本按照申请书设定的目标完成了任务：发现并证实CD40可以促进MDSC凋亡；然而新鉴定的一群以CD40+为特征的MDSC亚群却能通过CXCR5途径趋化MDSC向肿瘤组织聚集。CD40与CD40+MDSC似乎发挥着截然不同的作用，机制还需要探讨。此外，项目组还通过临床病例研究，分析了胃癌患者体内MDSC与Treg之间的关系以及临床意义；动物实验研究了黄芪多糖对MDSC的调控作用。受基金资助，申请人为通讯作者（含并列通讯1篇）合计发表与课题相关SCI论文5篇，单篇最高IF>5；核心期刊论文3篇；培养博士研究生3名；硕士研究生3名。