MIF通过Mincle激活M1巨噬细胞介导急性肾损伤的机制研究

Acute kidney injury is a common critical disease and has a poor outcome. However, its mechanism remains unclear. Inflammation plays an important role in maintaining tubular injury after AKI. We have recently reported that macrophage migration inhibitory factor (MIF) plays a pathogenic role in AKI as genetic or chemical blockade of MIF protected against AKI in mice, and this was associated with the inhibition of M1 macrophages activation. What is the mechanism by which MIF promotes M1 macrophages activation? This is a problem need further investigation. A novel observation from our preliminary studies is that Mincle is a key membrane protein for triggering and maintaining the M1 macrophage activation in AKI. Our preliminary study found that: Mincle-expressing M1 macrophages were largely reduced in MIF knockout (KO) mice; In vitro study revealed that, MIF enhances Mincle expression in bone marrow derived macrophages (BMDM), siRNA knockdown of Mincle suppressed MIF induced M1 macrophage activation in BMDM, which was associated with Mincle-NF-κB-Syk suppression. We thus hypothesized that MIF may mediate AKI by activating M1 macrophages via the Mincle-NF-κB-Syk. This hypothesis will be examined by using approaches such as generating AKI model in macrophage specific Mincle knockout mice and MIF stimulation in bone marrow derived macrophages. We expect to find evidence that MIF directly activates M1 macrophages through the Mincle-NF-κB-Syk in AKI. These results may lead to development of MIF and/or Mincle as potential novel targets for effective treatment of AKI.

急性肾损伤(Acute Kidney Injury, AKI)是组临床常见危重急症，机制不清。巨噬细胞M1活化是AKI加重的重要因素。既往研究发现基因或药物阻断MIF减轻AKI，与MIF促进M1活化相关，但MIF如何激活M1机制尚不清楚。申请人前期研究证明Mincle是触发M1活化的关键膜蛋白，体内外预试验显示：AKI状态下MIF可增加巨噬细胞Mincle表达及M1活化；siRNA阻断Mincle可以抑制MIF对骨髓来源巨噬细胞M1的活化，且与NF-κB-Syk被抑制相关。因此，本研究提出MIF或可调节Mincle转录，通过NF-κB-Syk激活M1介导AKI的发生。项目拟在条件性敲除Mincle小鼠构建AKI模型再注射MIF的方法及体外实验，探索MIF通过Mincle介导M1活化促进AKI的分子机制。为临床通过阻断MIF介导的巨噬细胞激活及炎症反应来治疗AKI奠定理论基础。

急性肾损伤(Acute Kidney Injury, AKI)是组临床常见危重急症，机制不清。炎症是AKI加重的重要因素。我们研究发现基因或药物阻断MIF减轻AKI，与MIF促进M1巨噬细胞活化相关，但MIF如何激活M1机制尚不清楚。我们前期研究证明Mincle是触发M1活化的关键膜蛋白，而体内和体外预试验显示：MIF可增加巨噬细胞Mincle表达及M1活化；siRNA阻断Mincle可以抑制MIF对骨髓来源巨噬细胞M1的活化，且与NF-κB-Syk信号明确相关。因此，本研究提出MIF或可调节Mincle转录，通过NF-κB-Syk激活M1介导AKI的发生。本研究发现，基因敲除MIF小鼠发生AKI时，肾脏Mincle表达减少，Mincle阳性M1巨噬细胞减少；体外试验证实，MIF可以增加骨髓来源巨噬细胞的Mincle表达水平，且呈时间和剂量依赖性；siRNA阻断CD74表达可以抑制MIF诱导的Mincle表达，以及Mincle阳性M1巨噬细胞活化；阻断NF-κB可以阻断MIF诱导的Mincle表达，以及Mincle阳性M1巨噬细胞活化；NF-κB-Mincle-Syk 形成一个环路来促进MIF诱导的Mincle表达途径。切段NF-κB-Mincle-Syk从而减少MIF引起的Mincle表达以及M1巨噬细胞活化，或可为临床通过阻断MIF介导的炎症反应治疗AKI建立新方法提供新思路。