IL-1β调控心外膜脂肪组织中巨噬细胞-脂肪细胞间炎症正反馈环路介导心脏纤维化的作用及机制

Inflammation is a pivotal factor in the initiation and promotion of cardiac fibrosis. Epicardial adipose tissue (EAT), the main source of inflammatory factors, is closely associated with atrial fibrosis. However, it’s unclear whether it is also association with ventricular fibrosis. Our preliminary experiment in rats with atherosclerosis (AS) showed that resection of EAT alleviated cardiac fibrosis after myocardial infarction. And in vitro experiment showed that exosome derived from EAT increased the volume of myocardial collagen, which could not be abrogated by RNase pretreatment. Further analysis of protein microarrays revealed that the expression of IL-1β was much higher in the EAT-derived exosome. Accordingly, our project intents to resolve the following scientific issues: 1) Whether macrophages interact with adipocytes in EAT to form a positive feedback loop resulting in the maintenance and amplification of inflammatory state in EAT; 2) Whether IL-1β is the key molecule in maintaining the inflammatory loop of EAT and the effector promoting cardiac fibrosis; 3) Whether exosome is the key way of the paracrine effect of EAT and plays a pivotal role in transporting IL-1β and promoting cardiac fibrosis. Therefore, our project intends to demonstrate the above scientific issues by building animal model of EAT resection, exosome tracing, gene interference and so on, which may provide new ideas and intervention targets for the therapy of cardiac fibrosis.

炎症是启动和促进心脏纤维化的关键因素。心外膜脂肪组织（EAT）中巨噬细胞含量丰富，也是心脏炎症介质的重要来源，与心房纤维化密切相关，但与心室纤维化的关系尚不清楚。我们发现，动脉粥样硬化大鼠去除EAT后可减轻心肌梗死后心脏纤维化。而在体外实验中，EAT源性外泌体可诱导心室肌胶原增多且RNA酶预处理并不影响该效应，蛋白芯片分析发现该外泌体IL-1β高表达尤为明显。由此，本项目拟解决如下关键科学问题：1. EAT中巨噬细胞是否与脂肪细胞发生相互作用，形成细胞间炎症正反馈环路以维持和放大EAT炎症状态；2. IL-1β是否维持EAT炎症环路的关键分子以及介导心脏纤维化的效应分子；3.外泌体是否EAT旁分泌作用的重要方式，在IL-1β运输及促心脏纤维化中起关键作用。为此，本项目拟通过构建去EAT动物模型，并利用外泌体示踪，基因干扰等方法论证上述科学问题，可能为心脏纤维化的治疗提供新的思路和干预靶点。

心脏成纤维细胞的激活是心肌纤维化的关键事件。糖酵解以及与糖酵解相关的lncrna在成纤维细胞激活中的作用尚不清楚。因此，我们通过寻找与糖酵解相关的lncrna，并在活化的人心脏成纤维细胞 (HCF)中验证其对HCF激活和糖酵解的影响。我们发现，TGF-β1诱导的HCF激活伴随着糖酵解的增强，而特异性糖酵解抑制剂可显著减弱HCF的激活。在鉴定出的28个与糖酵解相关的lncrna中，Linc00092的表达与HCF激活显著相关。在人心脏组织中，Linc00092主要在心脏成纤维细胞中表达。Linc00092基因敲低可促进HCF的激活并增强糖酵解，而过表达Linc00092可抑制HCF的激活并下调糖酵解。恢复糖酵解可消除Linc00092的抗纤维化作用。除此之外，Linc00092抑制活化的HCF中的ERK激活，而抑制ERK可以减轻Linc00092敲低所导致的纤维化表型。上述结果提示Linc00092可以通过抑制糖酵解来抑制HCF的激活。Linc00092对ERK的抑制作用可能在这一过程中起重要作用。该研究不仅有助于我们更好的理解成纤维细胞的激活机制，而且可能成为心肌纤维化治疗的新靶点。