JAK2/STAT3信号通路调控exFoxp3 Th17与根尖周骨破坏

The findings of our previous NSFC project imply the presence of CD4+Foxp3+IL-17+ T cells possibly as an intermediate phenotype between Treg and Th17 during the pathogenesis of periapical disease. It was newly discovered that unstable Treg under inflammatory conditions would lose Foxp3 expression (exFoxp3) and transdifferentiate into a novel strong pathogenic sunbset - exFoxp3 Th17. Of note, JAK2/STAT3 was demonstrated to drive exFoxp3 Th17 formation. Therefore, we proposed a new hypothetic model that exFoxp3 Th17 controlled by JAK2/STAT3 is critically involved in the pathology of periapical bone destruction. Thus the thesis is devided into three parts: Part one is in vivo experiment: JAK2/STAT3, exFoxp3 Th17, and RANKL are detected and measured in human periapical tissues obtained as biopsy samples during periapical surgery, and in experimental periapical lesions of Foxp3-fate reporter mice, conditional knockout mice, as well as in vivo adoptively transfer model. Part two is in vitro experiment: 1.The co-culture system of induced exFoxp3 Th17 and osteoclasts is performed, then the osteoclastogenic potential is analysed. 2.The three-dimensioned co-culture system of induced exFoxp3 Th17 and osteoblasts is also established, then morphological and functional assessment of osteoblasts is carried out. Therefore, the present project may deepen molecular understanding of periapical bone destruction and further figure out the role of T cell-mediated immune response in osteolytic diseases.

课题组前一项国家自然科学基金项目的研究结果提示根尖周病灶存在一群介于Treg和Th17之间的中间表型-CD4+Foxp3+IL-17+细胞。新发现不稳定型Treg在炎性刺激下将丢失Foxp3表达（exFoxp3），进而“叛变”转分化为强致炎性T细胞新亚群-exFoxp3 Th17，而JAK2/STAT3信号活化是其转分化生成的扳机点。本课题提出JAK2/STAT3信号通路调控exFoxp3 Th17影响根尖周骨破坏的新假设，拟通过人病变组织、基因谱系追踪转基因鼠和过继转移示踪模型等，研究JAK2/STAT3信号及exFoxp3 Th17在根尖周病中的可能作用；同时将JAK2/STAT3信号干预下exFoxp3 Th17分别与破骨细胞、成骨细胞共培养，以探讨其参与根尖周骨破坏的机理。本系列研究对进一步阐明根尖周病骨破坏机制和全面认识T细胞介导的免疫反应在溶骨性疾病中的作用都具有重要意义。

近年来研究发现Treg表型并不稳定，存在以CD4+ CD25lowFoxp3+为特征的不稳定型Treg，炎性刺激下可下调甚至丢失Foxp3表达形成exFoxp3 Th17细胞。该细胞可分泌数倍抬升的IL-17和RANKL，从而表现更为显效的致炎和促破骨作用。而JAK2/STAT3信号活化则是Treg表型丧失及其分泌IL-17的扳机点。本课题拟通过人病变组织、基因谱系追踪转基因鼠和过继转移示踪模型等，研究JAK2/STAT3信号及exFoxp3 Th17在根尖周病中的可能作用。结果发现人根尖周病变组织和小鼠根尖周病动物模型中，STAT3与p-STAT3的在根尖周炎的表达显著高于对照组，且检测到p-STAT3在exFoxp3 Th17细胞中的表达。小鼠根尖周病模型中，STAT3抑制剂AG-490和STA-21干预后，小鼠根尖周骨破坏明显少于对照组，STAT3的活化以及exFoxp3 Th17细胞的数量明显低于对照组。另外合成载有异甘草素（ISL)的介孔硅（MSN）纳米颗粒缓释体系，发现其通过抑制NF-κB和MAPK信号通路显著减少破骨细胞形成，并防止小鼠颅骨炎性骨吸收。本系列研究对进一步阐明根尖周病骨破坏机制和全面认识T细胞介导的免疫反应在溶骨性疾病中的作用都具有重要意义。