Shifting Landscapes: Dynamic changes from pro-to antiinflammatory Leukocyte phenotype in myocardial Ischemia/Reperfusion Injury

Pia Kröning^1,2*Nancy Schanze^1,3Katharina Naber^1,2Daniela Stallmann^1,2Maximilian Mauler^1,2Daniel Duerschmied^1,2,3,4,5Dirk Westermann^1,2Nadine Gauchel^1,2

• ¹Department of Cardiology and Angiology I, University Heart Center Freiburg, Bad Krozingen, Germany
• ²Faculty of Medicine, University of Freiburg, Freiburg, Germany
• ³I Medical Clinic for Cardiology, Angiology, Hemostaseology and Internal intensive care medicine, University Medical Centre Mannheim, University of Heidelberg, Heidelberg, Baden-Württemberg, Germany
• ⁴European Center for Angioscience, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Baden-Württemberg, Germany
• ⁵Partner Site Heidelberg/Mannheim, German Centre for Cardiovascular Research (DZHK), Heidelberg, Baden-Württemberg, Germany

Background: The temporal and spatial dynamics of platelet–leukocyte complex (PLC) formation in myocardial ischemia reperfusion injury (I/R injury) .are still ill defined. Aim: To investigated the kinetics and spatial differences of platelet-monocyte -complexes (PMC) and platelet-neutrophil -complexes (PNC) complex formation in relationship to with cardiac function parametersover the first 7 days in a mouse model of myocardial (I/R injury).Methods: A time-course study was conducted (up to seven days in order t) was used to evaluate immune cell response and cardiac function following myocardial I/R injury. Myocardial I/R injury was induced by ligation of the left anterior descending coronary artery (LAD) for 30 minutes followed by reperfusion. Using flow cytometry leukocyte and platelet markers were evaluated in the heart, blood, spleen, and bone marrow. Echocardiography was performed in order to measure ejection fraction and fractional shortening which are accepted as indicators of cardiac function.Results: Expression of CD206-Geometric Mean Fluorescence Intensity (GMFI) indicative ofting an anti-inflammatory phenotype in neutrophils (N2) increased in PNCs at day 7. A statitstically significant decrease in the percentage Percentage of anti-inflammatory Ly6Clow PMCs (M2 PMCs) was significantly lower when compared to baseline observed as early as day 3, when compared to the baseline value. Flow cytometry analysis showed no significant variationsdifference in PNCs or PMCs within the area at risk (AAR) at indicated time points across the specified time points.. Increase A rise in neutrophils and monocytes is observed in the AAR, reaching its peak peaks on day 3.Conclusion: Our resultsThe present study demonstrates show that both anti-inflammatory Ly6Clow monocytes (M2) and N2 neutrophils participate in PLC formation following myocardial infarction (MI) and reperfusion. Our results suggest that the N2 phenotype prerequisite for PLC formation in AAR at day 7. These findings offer suggest that targeted interventions may be developed promising avenues for the development of targeted interventions to improve outcomes after myocardial I/R injury.