TGFβ1在Ly6Chi单核细胞来源朗格汉斯细胞的表达对接触性皮炎的负向调控作用及机制研究

Langerhans cell(LC) play an important role in allergic contact dermatitis(ACD), however the regulatory mechanism is not clear at present. In our preliminary study, we found that TGFβ1 was dispensable for the development of Ly6Chi monocyte derived LC (Ly6Chi mo-LC), but it can suppress the expression of MHCII molecule in Ly6Chi mo-LC. Moveover, the inflammatory reaction was aggravated in the process of ACD if Ly6Chi mo-LC didn't express TGFβ1. Accordingly we made the scientific hypothesis as follows: because of deficient express of TGFβ1, the biological characteristics and function of Ly6Chi mo-LC was changed or antigen-specific T cell immune response and differentiation were changed, then it plays a critical of inducing T cell-mediated immune response, then result in negative regulation in the process of ACD. In this study, we will do experiments with LyzM-TGFβ1deficient mice and all kinds of chimeras mice models to address the role of TGFβ1 of Ly6Chi mo-LC in inducing antigen-specific T cell immune response and differentiation by virtue of modern immunological techniques. Further study will confirm the effect of Ly6Chi mo-LC which express TGFβ1 on the inflammation of ACD and its molecular mechanism. The study will contribute to understand deeply the role of Ly6Chi mo-LC which is regulated by TGFβ1 in ACD, to elucidate the underlying pathogenesis of allergic diseases such as ACD. It will provide a protential and theoretical basis for clininal diseases' theropies and exploiting new immunoregulatory drug in the future.

经典朗格汉斯细胞（LC）对接触性皮炎（ACD）具有调控功能，但Ly6Chi单核细胞来源LC（Ly6Chi mo-LC）在疾病中的作用及调控机制不清楚。前期预实验发现：TGFβ1在Ly6Chi mo-LC的表达缺失可导致细胞自身MHCⅡ分子上调，ACD炎症反应加重。据此推测，Ly6Chi mo-LC来源的TGFβ1可结合自身TGFβR，改变细胞内关键信号分子及分泌性因子谱；或直接作用于T细胞，促使Ly6Chi mo-LC在ACD中介导T细胞应答功能发生变化如抑制Th1分化，进而对ACD炎性反应具有负向调控作用。本项目以现代免疫学方法结合髓系细胞特异的TGFβ1缺陷鼠和骨髓嵌合鼠模型为实验平台，分析Ly6Chi mo-LC表达的TGFβ1在介导T细胞应答中的作用，探讨TGFβ1在Ly6Chi mo-LC的表达对ACD炎症反应的负向调控机制，有助于深刻理解不同LC亚群在维持皮肤免疫自稳中的作用。

变应性接触性皮炎（Allergic contact dermatitis, ACD）是皮肤或粘膜单次或多次接触致敏物后，由T细胞介导的迟发型变态反应引起的炎症性皮肤病。ACD发病机制复杂，严重影响人们的生活质量。本项目原计划围绕 “TGFβ1在Ly6Chi mo-LC中的表达对接触性皮炎的作用及调控机制”这一科学问题开展研究，实验过程中由于CD11c-TGFβ1-/-小鼠不是纯C57BL/6小鼠背景，所以其抗原提呈功能实验不宜进行，对该部分实验内容进行微调整。通过TGFβ1与小分子microRNAs和CX3CR1之间的联系，使用CX3CR1gfp/gfp 小鼠和miR146aKO小鼠对课题展开深入研究，探讨了TGFβ1和CX3CR1的表达对UV或ACD诱发皮炎过程中对Ly6Chi单核细胞来源的short-term LCs 形成的影响及调控作用，同时也使用TLR激活剂模拟研究miR146a在病原体感染过程中对DC表型和功能的影响，以期对临床皮肤炎症性疾病的发病机制及临床诊疗提供理论依据。研究成果总结如下：.皮炎发生过程中，表皮LC的重构由两个群体组成，即来源于局部或骨髓前体细胞发育的long-term LCs，以及来源于外周血中Ly6Chi单核细胞发育的short-term LCs。目前对于经典LC发育和功能调控研究已较深入，但对于short-term LCs 的形成机制及功能尚不清楚。本研究应用lyzm-TGFβ1-/-和CX3CR1gfp/gfp转基因小鼠以及骨髓嵌和鼠模型探讨Ly6Chi单核细胞发育和迁移机制，并利用UV照射和ACD疾病模型验证在皮炎发生过程中Ly6Chi单核细胞来源的short-term LCs形成的调控机制。我们发现，稳态下TGFβ1在髓系细胞中表达缺失导致外周血中Ly6Chi单核细胞数量减少；但是皮肤炎症状态下，CX3CR1的表达缺失导致外周血中Ly6Chi单核细胞比例上调。进一步在皮肤炎症中发现TGFβ1和CX3CR1的表达缺失均影响皮肤炎症部位Ly6Chi单核细胞来源的short-term LCs的生成；同时使用骨髓嵌和鼠模型和单核细胞回输实验确定Ly6Chi单核细胞迁移功能障碍导致short-term LCs细胞的减少。为继续探讨TGFβ1和CX3CR1的表达缺失导致short-term LCs细胞数量减少的机制，利用miR146aK