Are Endothelial Cell and Granulocyte Protein Arginine Deiminase 4 on the Pathway of Inflammasome-Activation, Advancing Myocardial Ischemia Reperfusion Injury?

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With the advances in percutaneous coronary intervention technology, the prognosis of patients with acute coronary syndrome has improved significantly over the last decades. However, approximately 6% of admitted patients do not survive hospital discharge and a decrease in cardiac function is still a common consequence of acute myocardial infarction, despite vigorous medical therapy. Increasing clinical and experimental evidence suggests that revascularisation itself triggers a pathological response termed myocardial ischemia-reperfusion (M/IR) injury. Experimental and clinical data suggests that MI/R injury may be responsible for up to 50% of the ultimate infarction area.Since the first description of M/IR injury by Jennings et al. in the 1960s it became evident that M/IR injury is an inflammatory-driven mechanism, in part depending on the infiltration of bone-marrow derived cells as well as the activation of classic inflammatory pathways. To unravel the pathophysiology of this process could help to attenuate M/IR injury. In 2014 Gao C. et al. discovered the activation of NLRP3-Inflammasome, a cytosolic protein complex that mediates the activation of pro-inflammatory caspases, ultimately resulting in the secretion of cytokines of the interleukin-1 family, in cardiac microvascular endothelial cells (CMECs) as a novel mechanism of MI/R injury. As of August 2019 Mishra N et al. showed that the Protein Arginine Deiminase 4 regulates NLRP3 Inflammasome activation in macrophages.In 2019 Wagner et al. demonstrated that NLRP3 Inflammasome activation plays an important role in the process of granulocyte Neutrophil Extracellular Traps (NETs) release, a form of defence mechanism originally intended to immobilize invading microorganisms consisting of a DNA scaffold decorated with granule-derived proteins. Over the years NETs have been implicated in a growing list of autoimmune and inflammatory conditions and in 2015 Ge L. et al. provided evidence for the existence of NETs in MI/R injury challenged myocardium. Whether endothelial cell and granulocyte Protein Arginine Deiminase 4 are on the pathway of Inflammasome activation and thus advancing myocardial ischemia reperfusion injury is yet to be established.The aim of the proposed project is to further investigate pro-inflammatory signalling pathways of MI/R injury in a mouse model using short-term ligation of the left anterior descending artery. Ex-vivo methods such as histology, gen expression analysis of blood and endothelial cells, protein analysis, flow cytometry and Immunofluorescence microscopy will be used. A comparative analysis of PAD4-/--, WT- and NLRP3-/-- mice will help to single out their individual function in MI/R injury potentially unveiling novel therapeutic modalities in attenuating MI/R injury.