Protective Effects of Therapeutic Neutrophil Depletion and Myeloperoxidase Inhibition on Left Ventricular Function and Remodeling in Myocardial Infarction

Figures

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  Figure 1. Polymorphonuclear neutrophil (PMN) reduction and myeloperoxidase (MPO) deficiency (Mpo−/−) alleviate inflammatory response after myocardial infarction (MI). (A) Schematic timeline of Ly6G antibody treatment, permanent left anterior descending artery (LAD) ligation (PI) and cardiac analyses: wildtype (WT) mice were treated with Ly6G antibodies 2 days before PI operation followed by cardiac investigations at days 2 and 7. (B) MPO plasma levels 2 and 8 days after PI assessed by ELISA. (C) Representative immunohistochemical Ly6G stainings (brown) of cardiac sections after 2 days of PI. Scale bar = 200 µm. (D) Quantitative analysis of Ly6G positive cells within the infarct and peri-infarct region 2 days after PI. n = 5/5/5/5; * p < 0.05, *** p < 0.001, **** p < 0.0001, ns = not significant; one way ANOVA test followed by appropriate post hoc test, mean ± SEM is shown.

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  Figure 2. Echocardiographic assessment of (A) left ventricular (LV) ejection fraction, (B) LV stroke volume and (C) LV end diastolic volume 7 days after PI. n = 4/10/8/11; * p < 0.05, **** p < 0.0001, ns = not significant; one way ANOVA test followed by appropriate post hoc test, mean ± SEM is shown.

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  Figure 3. Structural remodeling after MI. (A) Representative Masson’s trichrome staining of murine hearts of WT baseline and after 7 days of PI. Scale bar: 1 mm. (B) Quantification of LV anterior wall thickness and (C) of left ventricular fibrotic areas. n = 4/8/8/8; * p < 0.05, ** p < 0.01, ns = not significant; one way ANOVA test followed by appropriate post hoc test, mean ± SEM is shown.

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  Figure 4. Myofibroblast transdifferentiation after MI. (A) Representative immunofluorescence stainings of murine cardiac sections 2 days after PI for the fibroblast marker discoidin domain-containing receptor 2 (DDR-2; green) and the myofibroblast marker α–smooth muscle actin (α-SMA; red) (blue = DAPI; scale bar = 100 μm). Arrows indicate double positive cells. (B) Quantification of myofibroblasts within the infarct and peri-infarct region. n = 5/5/5; **** p < 0.0001, ns = not significant; one way ANOVA test followed by appropriate post hoc test, mean ± SEM is shown.

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  Figure 5. Connexin 43 (Cx43) expression in peri-infarct region. (A) Representative immunofluorescence stainings of murine cardiac sections after 2 days of PI for Cx43 (green = Cx43, blue = DAPI; scale bar = 50 μm). (B) Quantitative analysis of relative Cx43 expression within the peri-infarct region compared with healthy myocardium. n = 6/4/5; * p < 0.05, *** p < 0.001, ns = not significant; one way ANOVA test followed by appropriate post hoc test, mean ± SEM is shown.

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  Figure 6. Pharmacological MPO inhibition mitigates cardiac remodeling and functional deterioration after MI. (A) Schematic timeline of MPO inhibitor treatment (AZM198) followed by LAD ligation and reperfusion (I/R) and final cardiac investigations. (B) Representative Masson’s trichrome stainings of murine hearts 21 days after I/R; scale bar = 1 mm. (C) Quantification of left ventricular fibrotic areas. (D) Quantitative analysis of LV ejection fraction, (E) cardiac output, (F) mean arterial pressure 21 days after I/R assessed by pressure–volume (PV) loop analysis. n = 5/7; * p < 0.05, ** p < 0.01, ns = not significant; one way ANOVA test followed by appropriate post hoc test, mean ± SEM is shown.