CXCL16/NKTs/IL-4/Jmjd3通路调控巨噬细胞M2极化参与急性肾损伤后期纤维化的研究

Macrophage M2 polarization plays a critical role in the renal fibrosis following acute kidney injury (AKI). But its modulation mechanism remains not fully clear. Previous studies have documented that natural killer T cells (NKTs) is correlated with macrophage M2 polarization. .This project is based on our previous findings that CXCL16/macrophage-T cells signaling and macrophage M2 polarization mediated by IL-4Rα contribute to renal fibrosis. By targeting the key point of CXCL16/NKTs/IL-4/Jmjd3 pathway, we will investigate the role of CXCL16/NKTs/IL-4/Jmjd3 pathway in renal fibrosis following AKI from gene, cells and animal levels. This study is aim to answer three questions: 1) Dose CXCL16 recruit NKTs to modulate macrophages M2 polarization in the development of renal fibrosis following AKI? 2) Dose IL-4 mediate macrophages M2 polarization regulated by NKTs in the progression of renal fibrosis post AKI ? 3) Dose Jmjd3 mediate macrophages M2 polarization induced by IL-4 during renal fibrosis in response to AKI ? We expect to explore the new pathway and key point of macrophage M2 polarization and provide new therapy strategy for renal fibrosis after AKI.

巨噬细胞M2极化在急性肾损伤（AKI）后期纤维化过程中起重要作用，但具体调控机制不明。研究证实，NKT细胞（NKTs）与巨噬细胞M2极化密切相关。本项目以我们前期发现的CXCL16/巨噬细胞-T细胞信号和IL-4Rα介导的巨噬细胞M2极化参与肾纤维化为基础，通过靶向干预CXCL16/NKTs/IL-4/Jmjd3通路的关键节点，从基因分子水平、细胞层次和整体动物水平探索该通路调控巨噬细胞M2极化在AKI后期纤维化中的作用。通过本研究回答三个科学问题：1）CXCL16是否募集NKTs调控巨噬细胞M2极化参与AKI后期纤维化？ 2） IL-4是否介导NKTs调控巨噬细胞M2极化促进AKI后期纤维化的作用？ 3）Jmjd3是否介导IL-4诱导巨噬细胞M2极化加重AKI后期纤维化的作用？期望寻找AKI后期纤维化过程中巨噬细胞M2极化调控的全新途径及节点，为临床上AKI后期纤维化的防治提供新思路。

急性肾损伤（AKI）后期进展性肾纤维化是AKI转变为慢性肾脏病（CKD）的高危因素，巨噬细胞在此过程中起重要作用。通过建立多种AKI后期纤维化模型，我们首先验证了CXCL16信号通过募集NKTs调控巨噬细胞M2极化，促进IL-4介导M2巨噬细胞-肌成纤维细胞转化（M2MMT）参与AKI后期纤维化。其次我们发现：药物毒性AKI和梗阻性肾损伤导致IL-4+-NKTs显著增加，药理性拮抗NKT细胞活性或CD1d基因敲除可抑制NKT细胞介导的Th2型细胞免疫应答和IL-4释放，进而抑制巨噬细胞M2极化和M2MMT减轻AKI后期纤维化；激动NKT细胞可上调IL-4表达，促进AKI向CKD进展；拮抗IL-4减轻AKI后期纤维化，而外源性给予IL-4加重AKI后期纤维化。通过应用Jmjd3特异性拮抗剂、Lyz2Cre+:Jmjd3f/f巨噬细胞和构建IRF4过表达质粒，我们继续深入研究IL-4调控的巨噬细胞内信号分子机制，证实IL-4/Jmjd3/IRF4通路调控巨噬细胞M2极化和M2MMT。最后，通过应用Lyz2Cre+:Jmjd3fl/fl、IRF4-/-小鼠、建立梗阻性损伤和叶酸诱导的AKI后期纤维化模型及骨髓细胞移植实验，我们阐明了Jmjd3/IRF4轴调控巨噬细胞M2极化和M2MMT参与AKI后期纤维化的作用。此外，拓展研究发现拮抗组蛋白赖氨酸N甲基转移酶或抑制STING/TBK1信号轴活性可减少骨髓源肌成纤维细胞积聚，抑制M2MMT，减轻AKI后期肾纤维化。本项目揭示了AKI后期纤维化过程中细胞因子介导的NKT细胞-巨噬细胞之间的通讯信息网络和关键节点，明确了CXCL16/NKTs/IL-4/Jmjd3/IRF4通路调控巨噬细胞转分化在AKI后期纤维化病理过程的作用机制，为临床防治AKI向CKD进展提供了新思路。