Dectin-1及其内源性配体过氧化物酶Prdx6在心肌缺血再灌注损伤中的作用及其机制研究

Mounting evidence suggested that inflammation and immune response play an important role in myocardial ischemia reperfusion (IR) injury. Damage-associated molecular patterns (DAMPs) were released from the ischemic heart, which could trigger macrophage inflammation through binding Pattern recognition receptors (PRRs). Our previous studies have showed that: 1) Dectin-1, one of PRRs, was highly expressed in the pro-inflammatory macrophages (also called M1 macrophages), which were recruited in the early phase after myocardial infarction; 2) We further demonstrated that infarct size (Evans blue/TTC staining) and cardiac function (assessed by echocardiography) were significantly improved in Dectin-1 knockout mice after myocardial IR, compared with wild type mice; 3) We identified a DAMPs-peroxiredoxin 6 (Prdx6) as an endogenous, activating ligand for Dectin-1, which was highly expressed in the heart after cardiac IR. These results indicated that Prdx6/Dectin-1 axis may contribute to cardiac IR injury. Thus, based on these findings, the present study aimed to further explored: 1) Prdx6 promotes inflammatory cytokines expression (such as TNF-α, IL- 1β, IL-6 and IL-23) in myeloid cells (including macrophages and neutrophils) through binding its receptor Dectin-1. And these pro-inflammatory cytokines further promote IL-17 production from γδT cells，and synergistically exaggerate cardiac injury. 2) Intervention of Prdx6/Dectin-1 axis on cardiac IR injury and its mechanisms in vivo. 3) Lastly, we will examine serum levels of Prdx6 and circulating Dectin-1+ myeloid cells in patients with acute myocardial infarction, and further explore the relationship between prdx6/Dectin-1 axis and infarct size assessed by magnetic resonance image (MRI). Our findings will provide new therapeutic target for ischemic heart disease.

炎症免疫反应在心肌缺血再灌注（IR)损伤起到重要作用。缺血释放的损伤相关模式分子（DAMPs）与模式识别受体（PRRs）结合介导巨噬细胞炎症。我们研究发现：1）心梗后早期聚集心脏的促炎性巨噬细胞表达较高的PRRs-Dectin-1；2）Dectin-1-/-小鼠IR后心梗面积和心功能较野生型显著改善；3）IR后心肌释放的DAMPs-过氧化物酶6（Prdx6）表达显著增高，且与Dectin-1结合，表明Prdx6/Dectin-1轴可能参与心肌IR损伤。因此，本课题将继续探索：1）Prdx6/Dectin-1轴介导髓系细胞炎症反应，释放促炎性因子，进而提高γδT细胞分泌IL-17，协同参与心肌损伤；2）干预Prdx6/Dectin-1轴对心肌IR损伤的作用及其机制；3）血清Prdx6水平、Dectin-1＋髓系细胞与临床急性心肌梗死的相关性。为防治缺血性心脏病提供新的治疗策略和干预靶点。

【背景】巨噬细胞介导的炎症免疫反应在心肌缺血再灌注（IR）损伤中发挥了重要作用。作为一种在活化巨噬细胞上表达的模式识别受体，Dectin-1能够调节机体的炎症免疫反应，然而Dectin-1在IR中的具体作用及其机制尚不明确。本研究旨在探索Dectin-1在心肌IR损伤中的作用及机制。.【方法】研究应用Dectin-1基因敲除小鼠、Dectin-1中和抗体及其激动剂，以及骨髓移植手段证实骨髓来源的Dectin-1在心肌IR损伤中的作用。而后通过流式细胞学技术、荧光定量PCR、免疫印迹及免疫荧光染色等方法探究Dectin-1对于免疫细胞浸润及机体炎症状态的影响。同时收集急性心肌梗死行支架治疗患者及造影正常患者外周血，通过流式细胞术检测其中Dectin-1+细胞的表达。.【结果】研究证实，Dectin-1在心肌IR损伤早期即明显升高，并主要在骨髓来源的巨噬细胞中表达。Dectin-1基因敲除以及使用了中和抗体后能明显改善IR后小鼠的心功能，促进巨噬细胞向M2极化、抑制Ly6C+单核细胞及中性粒细胞的浸润，并减少心肌细胞凋亡。与此同时，使用Dectin-1激动剂后则具有相反作用。进一步研究发现，Dectin-1主要通过调节趋化因子CXCL1及G-CSF的表达来促进中性粒细胞集聚，并通过调控IL-23/IL-1β来影响γδT细胞分泌IL-17A，进一步介导中性粒细胞的集聚及心肌损伤过程。此外，通过临床研究证实，与造影正常患者相比，急性心肌梗死行支架治疗的患者外周血中Dectin-1+单核细胞数量显著增加。.【结论】Dectin-1在心肌IR损伤中发挥了重要作用，与临床急性心肌梗死密切相关，或可成为缺血性心肌病新的治疗靶点，具有重要的转化医学价值。