THE REGULATION OF NEUTROPHIL EXTRACELLULAR TRAPS (NETS) BY ADENOSINE IN MYOCARDIAL ISCHEMIA-REPERFUSION

项目摘要/摘要 缺血心脏再灌注是心肌梗死患者的救命手段，但其生理过程 再灌注引发的损伤可能会导致后续的损伤。先天免疫系统在 再灌注损伤。中性粒细胞释放多种毒性介质及中性粒细胞作用的评价 细胞外陷阱(Nets)在MI/R病理生理学中的作用日益重要。众所周知，腺苷可以缓解许多 当死亡和坏死细胞释放三磷酸腺苷时，促炎免疫过程激活免疫细胞。 ATP通过在包括间充质细胞在内的许多细胞上表达的胞外核苷酸酶代谢成腺苷 基质细胞(MSCs)。已知间充质干细胞高表达胞外核苷三磷酸二磷酸水解酶-1 (NTDPase1，CD39)和胞外5‘-核苷酸酶(CD73)。对嘌呤能代谢的调节可能是一种强大的 骨髓间充质干细胞用来抑制自身骨髓炎症的机制以及移植到 治疗目的。 目前对净生产的内生调节知之甚少，我们假设 腺苷可能是一种关键的内源性调节因子。我们的初步数据显示，MSC移植到 海藻酸盐包裹的心脏可以调节MI/R所致的固有炎症反应。 微囊化的MSCs可增加心肌腺苷水平，减少活性氧物种，并降低 24小时后心脏内白细胞和中性粒细胞的数量。我们将使用人类中性粒细胞以及 从缺乏关键腺苷受体的小鼠分离的中性粒细胞了解腺苷信号转导的作用 在MI/R中，我们还将使用MI/R的啮齿动物模型在体内测试我们新的网络调节策略。结果是 这些研究将确定治疗先天免疫性MI/R损伤的新治疗策略。 我们的目标是1)阐明腺苷受体2A(A2A)信号在调节 Net形成；2)评估参与Net调控的细胞内信号通路；3)测试其可行性 MSC对嘌呤能代谢的调节以预防心肌梗死/再灌注时的Net

PROJECT SUMMARY/ABSTRACT Reperfusion of the ischemic heart is lifesaving in myocardial infarction, but the physiologic processes triggered by reperfusion can cause subsequent damage. The innate immune system plays a prominent role in reperfusion injury. Neutrophils release multiple toxic mediators and the appreciation of the role of neutrophil extracellular traps (NETs) in MI/R pathophysiology is gaining importance. Adenosine is known to mitigate many pro-inflammatory immune processes while ATP released from dying and necrotic cells, activates immune cells. ATP is metabolized to adenosine by ectonucleotidases expressed on many cells including mesenchymal stromal cells (MSCs). MSCs are known to highly express ecto-nucleoside triphosphate diphosphohydrolase-1 (NTDPase1, CD39) and ecto-5’-nucleotidase (CD73). Modulation of purinergic metabolism may be a powerful mechanism used by MSCs to inhibit inflammation in their native bone marrow as well as when transplanted for therapeutic purpose. Currently little is known about endogenous regulation of NET production and we have hypothesize that adenosine may be a key endogenous regulator. Our preliminary data shows that MSC transplanted to the heart encapsulated in alginate can modulate the innate inflammatory response to MI/R. Furthermore, encapsulated MSCs increase myocardial adenosine levels, reduce reactive oxygen species, and decrease the number of leukocytes and neutrophils in the heart after 24 hours. We will use human neutrophils as well as neutrophils isolated from mice lacking key adenosine receptors to understand the role of adenosine signaling in MI/R. We will also use a rodent model of MI/R to test our novel NET-regulatory strategy in vivo. The results of these studies will identify new therapeutic strategies for treatment of innate immune MI/R injury. It is our aims to 1) delineate the importance of adenosine receptor 2A (A2A) signaling in the regulation of NET formation; 2) evaluate the intracellular signaling pathways involved in NET regulation; 3) test the feasibility of MSC modulation of purinergic metabolism to prevent NETs in MI/R.