LncRNA RP11-714G18.1调控MAPK信号通路对炎症刺激下血管内膜增生的作用机制研究

Endotoxins, such as LPS, induced smooth muscle cells (SMC) proliferation and subsequent augmentation of intimal hyperplasia are strong risk factors for cardiovascular disease. Our previous studies indentified a novel lncRNA RP11-714G18.1 with significant reduced expression in human advanced atherosclerotic plaque tissues, which suppressed SMC migration. However, the factors inducing the downregulation of RP11-714G18.1 in human arterial intimae and the underlying mechanism remain elusive. It is known that TLR4 and the downstream MAPK signaling pathway are crucial for LPS induced neointimal hyperplasia. Using both mouse model and human cell culture, our preliminary results showed that LPS markedly induced the phosphorylation of MAPK, including ERK1/2, and SAPK/JNK, and increased neointima formation in femoral artery wire injury model. Meanwhile, downregulation of RP11-714G18.1 was observed in LPS-treated SMC. Overexpression of RP11-714G18.1 suppressed SMC proliferation and reduced LPS-induced phosphorylation of ERK1/2 and SAPK/JNK. Therefore, we proposed that RP11-714G18.1 suppressed LPS-induced SMC proliferation via the regulation of MAPK signaling pathway, and play a protective role in neointimal hyperplasia. Understanding the mechanistic role of RP11-714G18.1 in LPS-induced neointimal hyperplasia may provide new therapeutic targets for atherosclerosis and restenosis.

炎症刺激下平滑肌细胞(SMC)增殖引起的血管内膜增生是众多心血管疾病的重要病理特征。我们前期研究发现lncRNA RP11-714G18.1 (RP11)在人动脉内膜斑块组织中表达下调，过表达RP11抑制SMC迁移。然而，导致RP11在人动脉内膜组织中下调的刺激因素及其影响SMC功能的分子机制尚不明确。已知TLR4及其下游MAPK信号通路在LPS刺激的血管内膜增生中发挥关键作用。预实验发现，体内外LPS能促进SMC增殖，降低RP11表达，同时增加ERK1/2和JNK磷酸化。过表达RP11抑制SMC增殖，削弱LPS引起的ERK1/2和JNK磷酸化增加。因此提出假说，RP11通过调控MAPK信号通路逆转LPS诱导SMC增殖，在内膜增生血管疾病中发挥保护性作用。本项目拟通过导丝损伤股动脉鼠模型，阐明RP11对炎症刺激下SMC增殖的作用及调控机制，为防治内膜增生血管疾病提供新的药物筛选靶点。

项目《LncRNARP11-714G18.1调控MAPK信号通路对炎症刺激下平滑肌细胞增殖的作用及机制研究》在初期进行过程中遇到阻碍，根据前期全转录组测序结果，ncRNA miR-223在人动脉内膜斑块组织中表达也是明显下调；提示miR-223在内膜增生性血管疾病也发挥保护性作用。进一步研究发现，体外miR-223通过调控PDGFRβ表达，抑制VSMC过度增殖；VSMC本身几乎不表达miR-223，活化的血小板能转移miR-223至VSMC，通过抑制VSMC增殖，抑制股动脉损伤引起的血管内膜增生；因此，项目内容由探究LncRNARP11-714G18.1调控平滑肌细胞增殖的作用及机制变更为探究血小板miR-223对炎症刺激下平滑肌细胞增殖的作用及机制研究。通过研究发现，体外miR-223通过调控PDGFRβ表达，抑制VSMC过度增殖；采用miR-223敲除小鼠(miR-223 KO)制备股动脉损伤小鼠模型，在股动脉处造成局部损伤，外源性加入miR-223 mimic (AgomiR-223)或者NC mimic发现，miR-223能通过降低PDGFRβ表达，抑制VSMC增殖，抑制股动脉损伤引起的血管内膜增生；平滑肌细胞本身不表达miR-223，在炎症刺激下，活化的血小板能转移自身miR-223至VSMCs，通过降低细胞PDGFRβ表达，抑制炎症引起的VSMCs增殖和去分化。该研究首次发现，活化的血小板能转移自身miRNA至血管平滑肌细胞，通过介导细胞间通讯，调控VSMC基因表达，影响细胞功能。申请人首次打破传统理论的局限，从全新的角度阐述血小板对血管动态平衡的调控。目前课题已完成，以第一作者发表高水平SCI论著2篇 (Circ Res，2020)，指导研究生发表SCI论著1篇 (Front Immunol, 2022)。获得广州市医学会优秀论文一等奖，申请国家专利1项。