Dectin-2-BCLAF1途径促进心肌缺血再灌注损伤及机制研究

Pattern recognition receptors (PRRs) are closely involved in the process of myocardial Ischemia/Reperfusion (I/R) injury. The present study showed that Dectin-2, a major C-type lectin-like receptors of the PRRs, is highly induced after myocardial I/R injury. Activation of Dectin-2 aggravated myocardial I/R injury via pro-apoptotic activities, pro-inflammatory reaction and abnormal autophagy. In a co-immunoprecipitation-mass spectrometry analysis, we uncovered that Bcl-2-associated transcription factor 1(BCLAF1), a novel Dectin-2 ligand, was significantly elevated. BCLAF1 stayed in nuclear physiologically and migrated to cytoplasm in hypoxia-reoxygenation. Over-expression of BCLAF1 crippled mouse cardiac function after I/R injury, and induced inflammation, apoptosis, and abnormal autophagy in myocytes in normal and hypoxia-reoxygenation status. During hypoxia-reoxygenation, Dectin-2 bound and phosphorylated BCLAF1. In the future study, we will verify the adverse effects of Dectin-2, BCLAF1 and Dectin-2-BCLAF1 pathway in myocardial I/R injury using wide-type and genetically modified mouse model with mechanisms regarding inflammation, apoptosis and abnormal autophagy probed. In addition, phosphorylation sites and interacting domain of BCLAF1 by Dectin-2 will be investigated.

固有免疫相关模式识别受体（PRR）参与心肌缺血/再灌注（I/R）损伤。我们发现I/R损伤心肌中PRR的成员Dectin-2表达增高，Dectin-2通路激活促进炎症、凋亡、自噬异常，加剧心肌I/R损伤。用免疫沉淀-质谱发现并证实，I/R损伤时Dectin-2的新配体-BCL2相关转录因子1（BCLAF1）升高。BCLAF1生理时分布于细胞核，缺氧复氧刺激后BCLAF1迁移至胞浆。高表达BCLAF1使小鼠心肌I/R后心功能减退；使缺氧复氧的心肌细胞炎症、凋亡和自噬异常加重；诱导巨噬细胞炎性反应。心肌I/R损伤时Dectin-2结合并磷酸化BCLAF1。后续将采用野生型和基因修饰小鼠，以体内外实验探讨Dectin-2、BCLAF1及Dectin-2-BCLAF1通路与心肌I/R损伤及疾病时炎症、凋亡、自噬异常的关系，寻找BCLAF1磷酸化位点和与Dectin-2结合功能域，阐明致病机制和途径。

固有免疫相关模式识别受体（PRR）参与心肌梗死后心脏重构过程。PRR的成员Dectin-2主要表达在髓系细胞表面。我们发现心肌梗死后早期心脏组织中巨噬细胞Dectin-2表达显著增高，提示其可能与心梗后炎症细胞功能有关。本研究中，我们通过比较野生型和Dectin-2敲除小鼠心梗后的梗死面积、基质重塑、心脏功能、生存曲线以及相关细胞因子的表达量来探究Dectin-2在心肌梗死后心脏修复中的作用。结果显示，与野生型小鼠相比，Dectin-2敲除小鼠心梗后的梗死面积，M1型和M2型巨噬细胞含量和比例均没有明显差异。但Dectin-2敲除小鼠梗死部位Ⅰ、III型胶原蛋白生成增多，基质金属蛋白酶-2/9减少，室壁厚度增加，成纤维细胞迁移加快，肌成纤维细胞生成增多；心功能明显改善；心梗后存活率因为心脏破裂降低而增加。进一步，我们发现，Dectin-2敲除小鼠心梗后心脏中Th1细胞比例减少，IL-12、IFN-γ表达均降低。以上的实验数据表明，心梗后Dectin-2通路激活，通过增加IL-12表达，促进Th0细胞向Th1细胞分化，从而增加缺血心肌中的IFN-γ的表达，导致心肌梗死后心脏修复过程受损，恶化心脏重构，促进不良预后。