钙敏感受体通过自噬活化NLRP3炎性体参与巨噬细胞介导心室重塑的研究

The prevention and reversion of cardiac remodeling, which is the fundamental mechanism and leading cause of heart failure post myocardial infarction (MI) has been an important issue. Recent evidence suggests that MФ play a dominant role in the process of MI. However, the mechanisms are still under investigation. We found for the first time the upregulation of calcium sensing receptor (CaSR), which along with the activation of NLRP3 inflammasome in myocardium-infiltrated MФ which could induce myocardial fibrosis, and autophage increased significantly in GdCl3 acticated THP-1 induced-MФ. Therefore, it is tempting to speculate that activation of CaSR in MФ during MI could induce the activation of autophagy, then it activates the NLRP3 inflammasome, which will result in the release of cytokines, such as IL-1β, from MФ and leads to the myocardial inflammation and fibrosis finally. In order to clarify the effect and mechanism of CaSR in MФ-mediated immunity during cardiac remodeling, we will study the regulation of CaSR expression, activation of autophagy and NLRP3 inflammasome, release of inflammatory factors and related cell signaling pathway in MI rat and cell culture model. Our research will give new insight into the mechanism of cardiac remodeling after MI and reveal that CaSR is a novel treatment target for cardiac remodeling. The conclusion of this study may provide scientific evidence for the effective treatment of heart failure.

心室重塑是心肌梗死（MI）后心力衰竭的基本机制和主要原因，如何逆转是医学难题。近年研究发现，在MI发展过程中巨噬细胞（MФ）占主导作用，但对其在心室重塑中的作用及机制缺乏研究。我们首次发现：MI大鼠心肌组织浸润的MФ上钙敏感受体（CaSR）表达上调、NLRP3炎性体活化增加，且发生心肌纤维化，同时观察THP-1诱导的MФ经CaSR特异性激动剂GdCl3作用后自噬增加。综上提出假设“MI后MФ中CaSR激活自噬，从而活化NLRP3炎性体，引起IL-1β等细胞因子释放从而导致心肌炎症和心肌纤维化，最终参与心室重塑”。本课题拟以模型大鼠以及细胞培养模型为研究对象，观察MФ中CaSR、自噬及NLRP3炎性体活化的变化规律及信号通路，阐明上述环节在心室重塑中的作用，为揭示MI后心室重塑的发生机制提供新视角，而抑制CaSR可能成为防治心室重塑的新靶点。本研究成果将为有效防治心力衰竭提供新的科学依据。

钙敏感受体（Calcium Sensing Receptor，CaSR）参与许多心血管疾病的病理生理过程，包括心肌梗死（Myocardial Infarction，MI）和高血压。CaSR的特异性抑制剂Calhex231在MI后心肌纤维化中的作用尚不清楚。使用Wistar大鼠，我们研究了Calhex231是否通过巨噬细胞的自噬-NLRP3炎性体途径改善MI后心肌纤维化。将大鼠随机分为假手术组（sham组）、MI组和MI + Calhex231组。与sham组大鼠相比，MI组大鼠出现严重的心功能、心肌纤维化和包括巨噬细胞在内的炎性细胞浸润。此外，MI大鼠的心肌组织炎症，包括NLRP3炎性体的激活和IL-1β分泌，以及自噬在浸润的心脏巨噬细胞和腹腔巨噬细胞中显著上调。Calhex231逆转了这些影响。在体外，研究发现CaSR特异性激动剂Calindol和自噬特异性激动剂雷帕霉素（Rapa）加剧了MI诱导的腹腔巨噬细胞自噬和NLRP3炎性体激活。Calhex231和自噬的特异性抑制剂（3-MA）可减弱自噬和NLRP3炎性体激活；而caspase-1抑制剂Z-YVAD-FMK则不能抑制自噬激活，却可减少NLRP3炎性体活化。另外，特异性抑制CaSR可改善MI后心肌组织焦亡情况，但具体机制尚待进一步研究。因此，目前的研究表明，Calhex231可能通过抑制自噬介导的NLRP3炎性体激活，改善MI后心脏功能并改善心肌纤维化；CaSR活化可介导心肌组织焦亡从而而导致心肌损害，这些研究结果均为CaSR成为防治心室重塑相关心血管疾病新的治疗靶点提供了理论依据。