STC2在间充质干细胞调控T淋巴细胞分泌炎症因子中的作用及机制研究

We have reported that MSC can inhibit T cell activation, proliferation and inflammatory cytokine secretion, but the mechanism is not clear (Cell Mol Immunol 2015.). We screened candidate gene STC2 through RNA-sequence technology and found that knockdown STC2 expressed in the MSC weaken the suppression ability on the secretion of IFN-γ and TNF-α by T cells. However,STC2 recombinant protein has no inhibitory effect on T cells. These suggesting that STC2 may be a new regulatory molecule, which down-regulates the proinflammatory cytokines of T cells through intracellular regulatory pathway. So the regulatory functions of STC2 that expressed in MSC and the mechanism of STC2 in regulating cytokines secretion are urgently answered. Therefore, we intend to demonstrate the regulatory function of MSC-derived STC2 in affecting T cell activation, proliferation in vivo and in vitro, especially in regulating the T cell cytokine secretion. Moreover, we will explore the regulating pathways, such as STC2-HO1, STC2-Ca2+, in the regulation of T cell cytokine secretion through STC2. These studies will not only help illustrate a new immunomodulatory mechanism by MSC, but also lay an important foundation for the further clarify the mechanism of MSC treatment of inflammation-related diseases.

申请人证实MSC能下调T细胞活化、增殖及炎症因子分泌（Cell Mol Immunol. 2015)，但MSC调控T细胞的机制不明确；利用RNA-seq技术筛选出STC2等候选调控分子，发现干扰STC2能下调MSC抑制T细胞分泌IFNγ、TNFα的能力，可重组STC2蛋白对T细胞却无抑制作用，提示STC2可能是新的调节分子且通过胞内调控机制影响T细胞；究竟MSC表达的STC2具有哪些功能以及STC2如何调控T细胞炎症因子分泌成为亟待回答的科学问题。据此，本项目拟利用体内外模型系统证明MSC表达的STC2对T细胞活化、增殖的影响，重点关注其在调控T细胞炎症因子分泌中的作用模式；进一步探讨STC2-HO1、STC2-Ca2+等STC2胞内调节通路在MSC调控T细胞炎症因子分泌中的作用机制。上述研究不仅有助于发现MSC免疫调节的新机制，也为进一步阐明MSC治疗炎症相关疾病的作用机制提供重要依据。

本研究旨在探讨间充质干细胞（mesenchymal stromal cells，MSCs）调控T细胞的细胞与分子机制，通过RNA-seq技术筛选出STC2等候选调控分子，利用基因沉默技术等证实STC2分子参与了MSC抑制T细胞分泌炎症因子IFN-r和TNF-a，同时利用接触性超敏反应模型体内证实了MSC能通过STC2抑制T细胞反应。进一步采用免疫荧光和免疫共沉淀技术发现MSC细胞中STC2与H01相互结合，STC2基因沉默不影响HO-1的表达，但是影响HO-1的活性进而抑制T细胞炎症因子的分泌。此外，还阐明MSC通过调节性CD28+CD28-T细胞和调节性CD23+CD43+B细胞调控T细胞反应，为挖掘MSC调控T细胞的机制、阐明MSC治疗的细胞与分子机制具有重大意义。