间充质干细胞通过Gal-9/Tim-3调控TH17/Treg细胞保护脓毒症肾损伤的机制研究

Mesenchymal stem cells (MSCs) become the hot topics in the treatment study of sepsis and acute kidney injury(AKI). However, the mechanism for MSCs in treatment of Sepsis-associated acute kidney injury (SA-AKI) is not well understood. Recent studies reported that Gal-9 can bind to the TH17 cell that express Tim-3, which induced the apoptosis of TH17 and inhibited the release of IL-17, Meanwhile, increased the regulatory T cells (Treg) and expression of IL-10. In previous study, we had confirmed that IL-17 plays a pathogenic role in SA-AKI. MSCs can alleviates SA-AKI by inhibition of IL-17 and induction of IL-10. Based on these results, our project raised the hypothesis that MSCs attenuate SA-AKI by inducing the balance of TH17/Treg through Gal-9/Tim-3. Firstly, the project designed to test the change of TH17/Treg and Gal-9/Tim-3 after MSCs in SA-AKI, Then, by blocking and activation of the pathway of Gal-9/Tim-3 in vivo and in vitro respectively to test the change of MSCs in SA-AKI and the differentiation of CD4+naiveT cell to TH17/Treg cell. Finally, though the above work, our study will provide novel theoretical support for clinical therapy of MSCs in SA-AKI.

间充质干细胞(MSCs)是脓毒症及急性肾损伤（AKI）治疗研究的热点，但MSCs治疗脓毒症肾损伤（SA-AKI）的机制尚无定论。近年发现Gal-9与表达Tim-3的TH17细胞结合可诱导TH17凋亡，抑制IL-17的释放，并诱导调节性T细胞(Treg)及其IL-10的表达。我们前期已证实IL-17参与SA-AKI发病，MSCs通过降低IL-17及升高IL-10改善SA-AKI。据此，我们提出：MSCs通过Gal-9/Tim-3调控TH17/Treg保护SA-AKI。为验证假说，本项目首先研究MSCs对SA-AKI肾脏TH17/Treg、Gal-9/Tim-3的影响，并进一步在体内外阻断及激活Gal-9/Tim-3通路，观察MSCs对SA-AKI的作用变化以及对CD4+naiveT细胞向TH17/Treg分化的影响，逐步探讨MSCs改善SA-AKI的作用机制，从而为其临床应用提供新的依据。

间充质干细胞(MSCs)具有免疫调控作用，包括抑制TH17细胞分泌IL-17诱导Treg细胞分泌IL-10等。本项目立项的主要目的是通过体内外试验逐层验证MSCs保护脓毒症肾损伤的可能机制。我们的前期研究已经证实MSCs可以改善脓毒症肾损伤，且MSCs干预后IL-17的表达明显减少，而IL-10的表达明显增加。同时我们的研究团队也证实MSCs可以诱导Treg分泌IL-10。文献证实Gal-9与表达Tim-3的TH17细胞结合可诱导TH17凋亡，抑制IL-17的释放，并诱导Treg分泌IL-10。据此，通过流式细胞学技术以及分子生物学技术我们证实了TH17/Treg失衡参与了脓毒症肾损伤的发病，且MSCs干预后可以重塑TH17/Treg平衡。我们又进一步在体内通过阻断及激活Gal-9/Tim-3通路，来进一步验证MSCs改善SA-AKI的具体机制，发现激活Gal-9/Tim-3可以改善SA-AKI，而阻断Gal-9/Tim-3通路后可以抵消MSCs对SA-AKI的保护作用，且其对IL-17的抑制和对IL-10的诱导作用不再具有统计学意义。该部分研究说明Gal-9/Tim-3通路是MSCs可以改善脓毒症肾损伤的重要环节。在体外我们也证实了MSCs能抑制CD4+naiveT细胞向TH17细胞的分化，而可以诱导CD4+naiveT细胞向和reg细胞的分化，而加入anti-Tim-3可以阻断MSCs对TH17细胞分化的抑制。综上所述，我们验证了MSCs通过Gal-9/Tim-3重塑TH17/Treg平衡改善SA-AKI的作用机制，为将来的临床应用提供了理论基础，同时也为进一步精准治疗提供了依据，我们希望在本项目研究基础上进一步明确MSCs调控Gal-9/Tim-3的具体机制。