IL-27/IL-27R调控DC活性及功能介导宿主抗衣原体免疫保护机制研究

IL-27/IL-27R signaling pathway plays an important role in both proinflammatory and anti-inflammatory efffects by regulating the differentiation and function of CD4+Th1 and Th17. Our privious study found that Chlamydia muridarum (Cm) respiratory infection induced higher IL-27 and IL-27R mRNA expression in lung tissue. We also found that IL-27R knock out mice (WSK-1-/-) are highly susceptible to chlamydia lung infection, with stronger Th17 immune response, higher inflammatory cytokines expression and much more inflammatory cells infiltration in lung tissue. We concluded that IL-27/IL-27R signaling pathway plays an important protective immunity in host against chlamydial infection. However, little is known about the concrete mechanisms of it. It is thought that dendritic cells are the key antigen presenting cells of host immune responses. Moreover, our previous studies indicated that IL-27/IL-27R may have inhibitation to dendritic cells, in that CD80 and CD86were highly expressed on spleen dendritic cells of WSK-1-/-mice. In this study, we will further explore the effect of IL-27/IL-27R signaling pathway on activation, proliferation, differentiation and function of dendritic cells together with their subsets, and demonstrate the prospective mechanisms of IL-27/IL-27R signaling pathway in host defense against Cm in the aspect of antigen presentation. We believe that our study will broaden the knowledge of IL-27/IL-27R signaling pathway and enrich the understanding of chlamydial infectious diseases.

目前研究显示IL-27/IL-27R信号途径可影响宿主CD4+T细胞分化，在感染性疾病中发挥促炎和抗炎双重作用。我们前期研究发现，IL-27R敲除小鼠(WSX-1-/-)对衣原体呼吸道感染高度易感，宿主抗衣原体特异性的Th17应答显著增高，肺组织大量炎症细胞因子表达及中性粒细胞浸润，引起严重的衣原体肺炎，这提示IL-27/IL-27R信号途径参与宿主抗衣原体免疫保护。重要的是我们发现WSX-1-/-小鼠树突状细胞(DC)高表达CD80及CD86，极有可能与Th17过度活化有关。本研究拟用衣原体感染的IL-27R敲除小鼠，深入探讨IL-27/IL-27R途径对DC活化、增殖、分化及细胞因子产生的影响，特别是利用DC-T细胞共培养及DC过继转移实验明确IL-27/IL-27R对DC功能以及与保护性T细胞反应之间的关系，从抗原提呈细胞角度阐明IL-27/IL-27R信号途径抗衣原体免疫保护机制。

沙眼衣原体作为一种专性胞内菌，常通过眼睛、生殖道和呼吸道引起粘膜感染导致沙眼、泌尿生殖道感染和新生儿肺炎。鼠型沙眼衣原体诱导的Th1应答通过产生IFN-γ发挥保护作用。树突状细胞(DC)作为重要的抗原提呈细胞，在感染时可启动相应T细胞应答。前期研究证实，在衣原体呼吸道感染中，IL-27/IL-27R能促进Th1细胞应答并在衣原体感染中发挥免疫保护作用，但IL-27/IL-27R促进Th1细胞应答与DC的活性（表型成熟和功能成熟）是否有关尚不清楚。.在本研究中，我们通过探索衣原体呼吸道感染下WT和WSX-1-/-小鼠DC比例、数目、亚群和活性的差异；分离并诱导WT和WSX-1-/-小鼠骨髓来源树突状细胞进行衣原体刺激观察两种不同来源BMDC的活性差异；采用过继转移和共培养技术探究衣原体呼吸道感染中IL-27/IL-27R对DC诱导CD4+T细胞和CD8+T细胞应答的影响，以揭示IL-27/IL-27R调控DC活性介导T细胞应答参与宿主抗衣原体免疫保护的具体机制。.我们发现衣原体呼吸道感染后第7天WT鼠DC中WSX-1表达显著升高。与WT鼠相比，WSX-1-/-鼠DC累积在Day7显著升高，而DC亚群在两者间无显著差异。此时WSX-1-/-鼠DC表面CD40、CD80、CD86表达高于WT鼠，同时DC中IL-10和IL-6 mRNA表达及DC培养上清中IL-10浓度也高于WT鼠。进一步研究发现，体外衣原体刺激诱导WT鼠源BMDC表面WSX-1表达升高，rIL-27抑制WT鼠源BMDC表面CD40表达，IL-12p40、IL-12p35、IL-6 mRNA表达及培养上清中IL-10和IL-6分泌。过继转移WT-DC和WSX-1-/--DC并进行衣原体呼吸道感染，通过监测体重、检测肺匀浆IFUs和分析肺组织炎症发现，WSX-1-/--DC受体小鼠在衣原体呼吸道感染后疾病加重且脾和肺中Th1细胞应答显著降低，Th17细胞、Th2细胞及CD8+T细胞应答无显著差异。此外，WT-DC和WSX-1-/--DC分别与衣原体致敏CD4+T细胞共培养，后者上清中IFN-γ分泌显著减少。.综上所诉，衣原体刺激可诱导DC上WSX-1表达。IL-27/IL-27R在衣原体呼吸道感染中可通过抑制DC中IL-10的表达和分泌从而促进Th1细胞应答发挥免疫保护作用。