MSC抑制脓毒症炎症反应新机制——旁分泌TGF-β诱导巨噬细胞极化

Uncontrolled inflammatory response is an important pathophysiologyis of sepsis induced organ injury. MSC can inhibit inflammation in sepsis, but the specific mechanism is unknown. M2 macrophage polarization is a key regulator of inflammation, which can be induced by MSC. In addition, TGF-β, an important M2 polarized macrophages regulatory factor can be secreted by MSC. Based on the mad is a important transduction factor of TGF-β, we assume that next MSC secrete TGF-β through TGF-β / Smad pathway regulating macrophage polarization is a key mechanism of MSC alleviate inflammatory response in sepsis. We will first establish the MSC of different TGF-β expression using lentivirus transfection. Observe the type of macrophages and cytokines expression after co-culture with macrophages to confirmed that MSC paracrine TGF-β to regurate macrophage polarization and reduce inflammation. Further in vitro experiments, we will activate or block TGF-β / Smad signaling pathway, to find the molecular mechanisms of this pathway to regulate macrophage. Finally, in vivo experiments to prove MSC paracrine TGF-β-induced macrophage polarization to reduce the inflammatory response in sepsis, which will provide the new ideas of treatment in sepsis.

失控的炎症反应是脓毒症损伤器官功能的重要病理生理机制。MSC能够有效抑制脓毒症炎症，然而具体机制不明。巨噬细胞向M2极化是调控炎症的关键，MSC能诱导巨噬细胞向M2的极化，并且能够分泌调节巨噬细胞向M2极化的重要调节因子TGF-β，结合 Smad是TGF-β重要转导因子，因此我们假设MSC旁分泌TGF-β经过TGF-β/Smad通路调控巨噬细胞极化是MSC减轻脓毒症炎症反应的关键。本项目首先采用慢病毒转染，建立表达不同TGF-β水平的MSC，与巨噬细胞共培养后观察巨噬细胞的类型以及炎症因子分泌的情况，证实MSC通过旁分泌TGF-β作用调控巨噬细胞极化，减轻炎症反应。进一步通过体外实验，激活或阻断TGF-β/Smad信号通路，明确该通路在MSC调控巨噬细胞极化作用及分子机制。最后通过在体实验证实MSC旁分泌TGF-β诱导巨噬细胞极化减轻脓毒症炎症反应，为脓毒症的治疗提供新的思路。

失控的炎症反应是脓毒症损伤器官功能的重要病理生理机制。MSC能够有效抑制脓毒症炎症，然而具体机制仍不明。巨噬细胞向M2极化是调控炎症的关键，MSC能诱导巨噬细胞向M2的极化，并且能够分泌调节巨噬细胞向M2极化的重要调节因子TGF-β，因此我们假设MSC旁分泌TGF-β调控巨噬细胞M2极化是MSC减轻脓毒症炎症反应的关键。本项目首先证实MSC通过旁分泌TGF-β调控巨噬细胞M2极化，减轻巨噬细胞介导的炎症反应。通过蛋白芯片分析发现，MSC旁分泌的TGF-β激活Akt/FoxO1通路，MSC旁分泌的TGF-β诱导FoxO1核输出，此外，Akt抑制剂以及FoxO1抑制剂可以阻断TGF-β对巨噬细胞M2极化的调控。为了进一步明确MSC旁分泌的TGF-β对脓毒症小鼠组织损伤以及炎症反应的治疗作用，我们利用慢病毒载体构建了高表达TGF-β的MSC，采用CLP复制脓毒症小鼠模型，经尾静脉注入高表达TGF-β的MSC。研究结果显示，MSC-TGF-β可以改善脓毒症小鼠的组织损伤，减轻炎症反应，抑制巨噬细胞在组织的浸润以及诱导其向M2极化可能是MSC-TGF-β发挥治疗作用的主要机制，这为脓毒症的治疗提供了新的思路。