银屑病血浆外泌体通过泛素化修饰调控Th17细胞分化的作用及分子机制

Th17 cells are one of the main players in the immunological dysfunction of psoriasis. However, the mechanism of Th17 differentiation and function excretion is not clearly understood. Nowadays, ubiquitination of transcription factors in T cells gain mounting attentions because of its regulation role in T cell differentiation. Exosomes are small membrane vesicles released by most cell types as a consequence of the fusion of multi vesicular endosomes with the plasma membrane. They play an important role in cell-cell communication, immune modulation and other physiology and pathological processes. Our previous studies demonstrated that psoriatic plasma exosomes can induce T cells proliferation and Th17 differentiation compared to healthy controls. Small RNA sequencing showed a distinct signature of microRNA profile between psoriatic plasma exosomes and healthy control exosomes. Bioinformatic analysis suggested key microRNA in psoriatic plasma exosomes may target E3 ubiquitin-ligase enzymes and thus regulate Th17 cell differentiation though ubiquitination of transcription factors. Here we will extract exosomes from psoriatic plasma, identify the regulation role of exosomes in Th17 differentiation through its microRNA cargos, and study the underlying mechanism. It will help us clarify the effect of psoriatic plasma exosomes on regulating T cells and represent its significance in the pathogenesis of psoriasis, providing a potential theoretical target for future treatment strategy.

Th17细胞是介导银屑病免疫紊乱的主要T细胞亚群，调控其分化和功能的机制尚未完全阐明。外泌体是活细胞主动向胞外分泌的纳米级囊泡样小体，主要介导细胞间物质和信号传递，在调节免疫应答及炎症反应等多种生理和病理过程中具有重要作用。我们研究发现，银屑病血浆来源外泌体可以显著促进T细胞的增殖及向Th17方向分化；高通量测序结合生物信息学分析发现银屑病血浆外泌体中高表达的miR-381-3p可能通过靶向调控泛素化E3连接酶的方式调节Th17细胞特征性转录因子，进而在Th17细胞分化和功能调控中发挥重要作用。本课题拟在前期工作的基础上，通过细胞及动物水平的研究，明确银屑病血浆外泌体调控T细胞分化的作用，揭示银屑病血浆外泌体中高表达的miR-381-3p调控Th17细胞增殖和分化的作用及其分子机制，明确银屑病血浆外泌体在介导T细胞免疫紊乱及银屑病发病中的意义，为未来可能的治疗策略提供新靶点。

银屑病是一种常见的慢性炎症性疾病，其中辅助性T细胞Th17已被证实是银屑病免疫学紊乱的核心内容，但调控其分化和功能的机制尚未完全阐明。本项目我们通过提取银屑病样角质形成细胞的外泌体进行研究，发现银屑病样角质形成细胞的外泌体被CD4+T细胞摄取后，可以显著促进CD4+T细胞分泌Th17相关转录/炎症因子，并促进CD4+T细胞向Th17方向分化。进一步测序分析发现，银屑病样角质形成细胞的外泌体与正常角质形成细胞外泌体相比其microRNA表达谱具有明显差异，有28个microRNA显著上调表达，114个microRNA显著下调表达。其中miRNA-381-3p在银屑病CD4+T细胞向Th17分化的调控中发挥了关键的调控作用。银屑病状态下角质形成细胞外泌体中的miRNA-381-3p从角质形成细胞中转移至CD4+T细胞，通过抑制下游靶基因UBR5和Foxo1，调控Th17的关键转录因子RORγt的蛋白水平，促进Th17的分化，进而参与了银屑病的发生发展。本项目首次揭示角质形成细胞外泌体在银屑病发病中的作用，并初步阐明了角质形成细胞外泌体参与银屑病病理过程的关键分子机制，为进一步完善了银屑病发病机制奠定基础。