piRNAs在血管紧张素II诱导的腹主动脉瘤形成中的作用及其机制

Abdominal aortic aneurysm (AAA) is not a real cancer, which is defined as a stretched and bulging section in the aortic wall, usually representing an underlying weakness at that location. Most aneurysms don't cause symptoms, however, they can burst or rupture. This causes severe pain and bleeding that can quickly lead to death. As a result, it is regarded as an intensive emergency medicine, as well as a fatal vascular disease. Although patients with asymptomatic AAAs can be detected and diagnosed by iconography methods, no preventive strategies or specific medicines can be adopted to prevent and revert the disease so far. It’s meaningful and also challenging to identify the pathogenesis and therapeutic targets for AAAs. Previously, we had investigated the noncoding RNAs expression profile in angiotensin II (AngII)-induce AAAs by high throughput DNA sequencing technology. It’s surpised to find that there were some piRNAs (Piwi-interacting RNAs) expressed significantly in these aneurysms. Using bioinformatics analysis to predict target genes, some AAA-associated piRNAs are candidated to target TNF-α, TGF-β and MMPs associated genes and validated in cell culture (ex vivo) and AngII-induce AAAs mice (in vivo). The present studies aim to investigate the role of piRNAs in the development of AngII-induce AAAs and explain their potential mechanisms, as well as detect the PIWI proteins and their members interacting with piRNAs in the aneurysmal tissues. These results might translate into clinical practice and provide the therapeutic strategies and targets for AAA patients. It’s also the first time to find and study the piRNAs in the vascular pathology, which might expand the limited knowledges of piRNAs in reproduction and development.

腹主动脉瘤是腹主动脉壁局部或弥漫性异常扩张，并非真正肿瘤。由于其潜在破裂风险，具极高的致死率，是最凶险的心血管危重急症。尽管影像学手段可早期发现无症状性腹主动脉瘤，目前尚无特效治疗，因而是急需攻克的医学难题。我们前期利用基因测序研究血管紧张素II诱导的小鼠腹主动脉瘤组织中非编码RNAs表达谱时，意外发现腹主动脉瘤中存在差异表达的piRNAs。利用生物信息学预测和选取调控TNF-α、TGF-β及MMPs等靶标基因的腹主动脉瘤相关piRNAs，分别从细胞和整体水平进行功能验证，研究其在血管紧张素II诱导的腹主动脉瘤形成中的作用及其机制。探索腹主动脉瘤组织中与piRNAs相结合的PIWI蛋白及其组件成分。本项目研究结果不仅为临床腹主动脉瘤治疗及药物研发提供靶标，具重要的临床指导意义，且开拓性地发现和尝试了piRNAs在血管病理中的研究，甚至有可能扩展已有的piRNAs局限在生殖发育中的认识。

腹主动脉瘤是腹主动脉壁局部或弥漫性异常扩张，由于其潜在破裂风险，具极高的致死率，但目前尚无特异性预防和药物治疗方法。利用基因测序研究血管紧张素II诱导的小鼠腹主动脉瘤组织中非编码RNAs表达谱时，发现腹主动脉瘤中存在差异表达的piRNAs，分别为piRNA-108610、piRNA-170669、piRNA-9311、piRNA-9312、piRNA-119321。通过qPCR验证腹主动脉瘤可特异性高表达piRNA-108610，但相应的PIWI蛋白（包括PIWIL1、PIWIL2、PIWIL4蛋白）并无显著性改变。利用生物信息学预测piRNA-108610对应的靶标基因为Rsad2，CCL7，Fmo2，Slc34a2，Hn1，进一步验证得到CCL-7（趋化因子配体7）在血管紧张素II诱导的腹主动脉瘤中较正常腹主动脉组织显著增高。使用CCL-7特异性中和抗体经腹腔注射到血管紧张素II诱导的雄性小鼠，结果发现CCL-7中和抗体可显著降低腹主动脉瘤的发生率，且独立于血压之外，可能通过调控巨噬细胞的迁移和分化发挥作用。本研究结果提示CCL-7中和抗体可能预防腹主动脉瘤的发生，为制定临床腹主动脉瘤的防治策略具指导意义。