bluuebunny/crossref_metadata_2025_split huggingface dataset:
Multidimensional immunoimaging to characterize the inflammatory reaction after permanent and temporary coronary artery occlusion in mice
Authors: Maier A , Toner Y C , Munitz J , Calcagno C , Fayad Z A , Mulder W J M , Van Leent M M T 
Published: October 2022

Abstract

Background
The immune response following acute myocardial infarction encompasses a delicate balance between inflammatory and reparative programs. Our knowledge of these complex mechanisms is mainly derived from studies using a murine model of permanent coronary artery occlusion. In this study we developed, validated and implemented multiparametric imaging methods to investigate cardiac function and the systemic immune response in transient or permanent coronary artery occlusion mouse models.

Methods
The myocardial infarction models encompassed either transient (40 min) or permanent LAD occlusion in C57BL/6 mice, and non-infarcted mice were used as controls. Two or seven days later, the animals subjected to systemic immunoimaging of the bone marrow, spleen and myocardium with late gadolinium enhancement cardiac MRI (LGE cMRI), 18F-fluorodeoxyglucose (18F-FDG) PET, 18F-Fluorothymidine (18F-FLT) PET, 64Cu-CCR2 PET targeting inflammatory monocytes, 89Zr-CD11b nanobody PET and 19F-HDL-PERFECTA MRI, both targeting myeloid cells. In addition, the same myocardial infarction models were applied to atherosclerosis-prone Apoe−/− and systemic inflammation and plaque progression were assessed by flow cytometry and immunohistochemistry four weeks after infarction.

Results
Through LGE cMRI and 18F-FDG PET, we observed that temporary coronary occlusion resulted in a smaller infarct size, better cardiac function and viability compared to permanent occlusion. Multiparametric immunoimaging targeting CD11b+ cells by 89Zr-CD11b nanobody PET and Ly6Chi inflammatory monocytes by 64Cu-CCR2 PET demonstrated that mice subjected to transient coronary occlusion had less immune cell influx to the ischemic myocardium. This finding was confirmed by flow cytometry analysis of the infarct zone. In contrast, both myocardial infarction models cause a similar systemic immune response in the bone marrow and spleen as observed with multimodal imaging with subsequent similar numbers of CD11b+ cells in the blood. Both permanent and temporary coronary artery occlusion aggravate atherosclerosis in Apoe−/− mice with higher macrophage and Ly6Chi monocyte numbers in aortas and larger plaque size compared to Apoe−/− mice without myocardial infarction.

Conclusions
We developed and employed multimodal, multiparametric imaging protocols to characterize the immune response in the heart, bone marrow and spleen in two models of myocardial infarction. While cardiac function was superior in the ischemia reperfusion model, both types of myocardial infarction accelerated atherosclerosis.

Funding Acknowledgement
Type of funding sources: Other. Main funding source(s): NIH and DFG
A closed-chest model of selective atrial myocardial infarction for the study of induced electrophysiological and structural derangements
Authors: Amoros-Figueras G , Casabella-Ramon S , Company G , Arzamendi D , Macias Y , Jorge E , Sanchez-Quintana D , Rosell-Ferrer J , Guerra J M , Cinca J 
Published: October 2022

Abstract

Background
The diagnosis of atrial infarction is often masked by the frequent association with ventricular infarction. For this reason, the electrophysiological and structural consequences of selective atrial ischemia are poorly understood.

Purpose
The objective of this study was to analyze the alterations in the ECG, local electrograms, and multifrequential atrial myocardial impedance in a new experimental model of acute and chronic atrial infarction.

Methods
Seven anesthetized pigs were subjected to 4h of atrial ischemia induced by selective catheter occlusion of the atrial coronary branches originating in the left circumflex coronary artery. The surface ECG was recorded and the changes in P-wave morphology analyzed. Four weeks later the animals were subjected to endocardial voltage mapping (Carto) and multifrequential impedance. The hearts were processed for anatomopathological study.

Results
Selective occlusion of the coronary atrial branches induced atrial infarction with fibrosis in the left atrium in 6 of the 7 cases (Figure). The surface ECG showed prolongation of the P-wave duration (Figure) (P-wave in lead II: from 72±8ms at baseline vs. 97±18ms at 4 weeks, ANOVA p&lt;0.01; P-wave in lead aVR: from 71±3ms at baseline vs 87±9ms at 4 weeks, ANOVA p&lt;0.01) with no appreciable displacement of the PR segment. Endocardial mapping of the left atrium showed low-voltage bipolar zones with decreased multi-frequency impedance phase angle values, as compared with preserved zones of the same atrium (bipolar electrograms: from 0.6±1mV to 2.0±1.9mV, T-Test p&lt;0.01; Phase angle at 300KHz: from −5.5±2° to −9.0±4.4° T-Test p&lt;0.05).

Conclusion
We developed a closed-chest swine model of selective atrial infarction suitable for the study of ECG patterns and electrophysiological mechanisms linked to atrial myocardial ischemia and infarction. The structural derangements are detectable by endocardial mapping of local voltage electrograms and local tissue impedance.

Funding Acknowledgement
Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Supported by grants from ISCI-MINECO (FIS PI17/00069), FEDER, CIBERCV (CB16/11/00276)
Hypothermia yields favourable cardiac energetics in experimental ischemia/reperfusion – insights from non-invasive pressure-volume loops by CMR
Authors: Berg J , Jablonowski R , Nordlund D , Ryd D , Heiberg E , Carlsson M , Arheden H 
Published: October 2022

Abstract

Background/Introduction
In experimental studies, mild hypothermia (&lt;35°C) has reduced infarct size [1], potentially through reduced reperfusion injury [2], but human trials have been ambiguous [3]. Furthermore, a pressure-volume (PV) loop framework is the gold standard for assessing cardiac performance, but the invasive approach limits its clinical use. Therefore, we used a porcine model of ischemia/reperfusion with cardiovascular magnetic resonance (CMR) imaging throughout one week to acquire non-invasive PV loops.

Purpose
To quantify the cardioprotective effects of hypothermia at reperfusion by serial CMR imaging in a perspective of cardiac energy and mechanics.

Methods
Normothermia and Hypothermia groups (n=7+7 pigs) were imaged with CMR at baseline and subjected to 40 minutes of normothermic ischemia by catheter intervention. Thereafter, the Hypothermia group was rapidly cooled (&lt;35°C) for 5 minutes before reperfusion. Additional imaging at two hours, 24 hours, and seven days were used to assess ventricular volumes and ischemic injuries. Infarct size was determined by high-resolution ex-vivo T1-weighted images.

Results
Figure 1 shows that stroke volume (SV: p=0.029; Friedmans test) and ejection fraction (EF: p=0.068) were notably reduced post-reperfusion in the Normothermia group. In contrast, the decreases were ameliorated in the Hypothermia group (SV: p=0.77; EF: p=0.13). Mean arterial pressure (MAP) was stable in the Normothermia group (p=0.77) but dropped two hours post-reperfusion in hypothermic animals (p=0.007). Over one week, both groups experienced the same decrease and partial recovery pattern for stroke work, external power, and ventricular-arterial coupling. Still, the adverse effects from ischemia were generally attenuated in the Hypothermia group. Although not significant, ischemia/reperfusion caused smaller infarcts in the Hypothermia group (10±8% vs 15±8%; p=0.32). The change in PV loop variables from baseline to 24 hours was compared with infarct size for each group. Though statistical power was limited, the general trend in analyses of covariance indicated that hypothermia has cardioprotective properties incremental to reducing infarct sizes (Figure 2), such as higher external power (p=0.061) and lower arterial elastance (p=0.015).

Conclusion
Using non-invasive PV loops by CMR, we observed that mild hypothermia before reperfusion results in favourable cardiac energetics that alleviates the heart's work after an ischemia/reperfusion injury during the first week. This study suggests that hypothermia has cardioprotective properties, incremental to reducing infarct size. The primary cardioprotective mechanism was likely an afterload reduction unloading the injured left ventricle.

Funding Acknowledgement
Type of funding sources: Foundation. Main funding source(s): The Swedish Heart-Lung FoundationThe Medical Faculty of Lund University (ALF)
S1P lyase inhibition improves post-ischemic cardiac remodeling independently of infarct size via S1P receptor 1
Authors: Polzin A , Dannenberg L , Benckhoff M , Barcik M , Keul P , Weske S , Ahlbrecht S , Helten C , Haberkorn S , Floegel U , Zeus T , Mueller T , Graeler M , Kelm M , Levkau B 
Published: October 2022

Abstract

Background
Revascularization of the infarct vessel is the golden standard in acute myocardial infarction (AMI). Even in Western countries, more than ten percent of AMI patients are so-called “latecomers” and it is controversial if revascularization of the infarct vessel is beneficial in these patients. Current guidelines even discourage revascularization of the infarcted artery if symptom onset was &gt;48 hours and the patient is asymptomatic. These patients are at high risk for cardiovascular events and heart failure with reduced ejection fraction (HFrEF). HFrEF has an enormous socio-economic impact, high morbidity, and mortality.

Purpose
Therapeutic options targeting post-ischemic cardiac remodeling are sparse. The bioactive sphingolipid sphingosine-1-phosphate (S1P) reduces ischemia/reperfusion injury when administered in advance. However, its impact on post-ischemic remodeling independently of its infarct size (IS)-reducing effect is yet unknown.

Methods
Acute myocardial infarction (AMI) in mice was induced by permanent ligation of the left anterior descending artery (LAD). C57Bl/6J were treated with the S1P lyase inhibitor 4-deoxypyridoxine (DOP) starting seven days prior to AMI to increase endogenous S1P concentrations. Cardiac function and myocardial healing were assessed by cardiovascular magnetic resonance imaging (cMRI), histomorphology and gene expression analysis. DOP effects were investigated in cardiomyocyte-specific S1P receptor 1 deficient (S1PR1 Cardio Cre+ and Cre− control) mice, and S1P concentrations measured by LC-MS/MS.

Results
S1P concentrations in plasma before induction of AMI were increased fourfold by DOP (Control 0.97±0.09μM [n=6] vs. DOP 3,80±0,09μM [n=6]). Scar size determined by MRI, as well as ejection fraction (EF), did not differ 24 h post AMI. In contrast, after 21 days, there was a clear difference between the two groups (scar size vehicle: 19.3±6.2% vs. DOP 13.4±5.7%; EF: Vehicle: 26.4±8.7% vs. DOP 38.2±11.8%). In addition, in the remote area 21 days post AMI in the DOP-treated animals, a reduced gene expression of brain natriuretic peptide, atrial natriuretic peptide and collagen 1a2. Finally, cardiomyocyte diameter in the remote myocardium was 21% smaller in DOP-treated (Vehicle: 21.95±1.59μm vs. DOP 17.35±0.77μm). The benefit of DOP-treatment was abolished in cardiomyocyte-specific S1PR1-deficient mice.

Conclusion
S1P improves cardiac function and myocardial healing post AMI independently of initial infarct size via S1PR1. Hence, in addition to its beneficial effects on I/R injury, S1PR1 may be a promising target in post-infarction myocardial remodeling as adjunctive therapy to revascularization and in patients who are not eligible for standard interventional procedures.

Funding Acknowledgement
Type of funding sources: None.
PCSK9 modulates the Wnt/beta-catenin signaling pathway in myocardial ischemia/reperfusion injury
Authors: Cha Y , Kim H E , Jeon S B , Park S W , Lee S H , Lee C J 
Published: October 2022

Abstract

Background
Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a protein that affects cholesterol homeostasis. Recent research has found that PCSK9 has various effects on the heart that are unrelated to LDL cholesterol regulation. The Wnt/β-catenin signaling pathway plays a crucial role during heart development, and it is re-activated in response to cardiac injury. Low-density lipoprotein receptor-related proteins 5 (LRP5) act as co-receptors of Wnt ligands and are indispensable for Wnt/β-catenin signal transduction. However, it is not fully elucidated whether other members of the LDLR-superfamily may be targets of PCSK9.

Purpose
This study aimed to determine if LRP5 is a PCSK9 target, study the association between PCSK9 and Wnt/β-catenin signaling, and elucidate its effect on myocardial infarction in patients with ischemic cardiomyopathy.

Methods
The expression of Lrp5, phospho-β-catenin, total β-catenin was evaluated by western blot analysis, and the effects of overexpressed PCSK9 were tested under normoxia, hypoxia, or hypoxia/re-oxygenation (H/R) in mouse cardiomyocytes (HL-1). The transcriptional activity of β-catenin was assessed using the TOP-Flash/FOP-Flash luciferase reporter assay. In addition, the impact on various downstream targets of the Wnt/β-catenin signaling pathway was assessed using a quantitative real-time polymerase chain reaction. To examine whether PCSK9 regulates injury of cardiomyocytes in vivo, we subjected transgenic mice with cardiac-specific overexpression of PCSK9 (PCSK9 TG) and wild-type (WT) mice to either sham surgery or ischemia/reperfusion (I/R) surgery.

Results
Under hypoxic conditions, the Wnt/β-catenin signaling pathway-related genes were downregulated in HL-1 cells, as evidenced by lower Lrp5 and active phospho-β-catenin expression levels (0.5-fold, n=3, p&lt;0.01). After H/R, the Wnt/β-catenin-related genes were recovered (1.5-fold, p&lt;0.01) in the control group but not in the PCSK9 overexpressed group. In the luciferase reporter assay results, PCSK9 overexpression inhibited the recovery of β-catenin transcriptional activity after H/R, in contrast to the control group. Furthermore, mRNA levels of Axin2, Cyclin D1, which are the Wnt/β-catenin signaling downstream pathway targets, were down-regulated under hypoxia and recovered after H/R but did not recover in PCSK9 overexpressed cells. In the mouse I/R model, the overall protein levels of the Wnt/β-catenin signaling-related genes were down-regulated in PCSK9 TG mice compared to WT mice after I/R injury.

Conclusions
These results indicated that the regulation of PCSK9 is closely associated with the Wnt/β-catenin signaling pathway which may play a crucial role in damaged cardiomyocytes. It suggests that the regulation of PCSK9 could be a therapeutic target in patients with ischemic cardiomyopathy.

Funding Acknowledgement
Type of funding sources: None.
Red blood cells induce endothelial dysfunction in patients with ST-elevation myocardial infarction and elevated C-reactive protein
Authors: Tengbom J , Collado A , Jiao T , Yang J , Zhou Z , Mahdi A , Pernow J 
Published: October 2022

Abstract

Background
The important role of inflammation in atherosclerotic plaque progression and instability leading to myocardial infarction has been widely demonstrated. C-reactive protein (CRP) has been shown to be of predictive value in atherosclerotic cardiovascular disease. The red blood cell (RBC) is an important regulator of cardiovascular function through nitric oxide bioactivity and oxidative stress in ischemic heart disease. Also, arginase-1 has been shown to greatly influence nitric oxide bioactivity in RBCs and to cause endothelial dysfunction. However, the mechanisms by which RBCs regulate vascular function in patients with myocardial infarction and its relation to inflammation and arginase-1 remain unknown.

Objective
The study aimed to investigate the effect of RBCs on endothelial function in patients with ST-elevation myocardial infarction (STEMI) and its possible association with systemic inflammation and arginase-1.

Material and methods
Blood samples were collected from patients with STEMI within 36 h after admission and from age-matched healthy controls. RBCs were incubated with isolated rat aortic segments for 18 h after which the aortas were assessed for endothelium-dependent and endothelium-independent relaxations using wire myographs and application of acetylcholine and nitroprusside, respectively. The vascular response was evaluated in relation to the level of inflammation defined as CRP &lt;2 and ≥2 mg/L at admission. The levels of 4-hydroxynonenal (4-HNE; a marker of oxidative stress formed by lipid peroxidation) and the expression of arginase-1 were visualized in rat aortas following incubation with RBCs by immunohistochemistry. All handling and procedures regarding human subjects and sampling were performed according to the Declaration of Helsinki. All animal experiments and procedures were performed according to the guidelines by the U.S National Institutes of Health (NIH publication no 85–23, revised 1996).

Results
RBCs from patients with STEMI and elevated CRP (≥2 mg/L, mean of 9.6 mg/L) induced significant impairment of endothelium-dependent relaxation compared to RBCs from patients with STEMI and low CRP (&lt;2 mg/L, mean of 1.0 mg/L) and to the healthy controls (Fig. 1). Endothelium-independent relaxations did not differ between the groups. Immunohistochemical staining of the aorta revealed that incubation with RBCs from patients with STEMI and high CRP increased the expression of 4-HNE and arginase-1 compared to incubation of RBCs from healthy controls and patients with STEMI and low CRP (Fig. 2).

Conclusion
RBCs from patients with STEMI and elevated CRP induce endothelial dysfunction and increase the expression of 4-HNE and arginase-1, indicating that inflammation is involved in the mechanism by which RBCs induce endothelial dysfunction in STEMI.

Funding Acknowledgement
Type of funding sources: Foundation. Main funding source(s): Swedish Heart and Lung foundation
Inhibition of coagulation factor XI attenuates inflammation in myocardial ischemia/reperfusion injury
Authors: Luo Q , Molitor M , Aluia M , Finger S , Wenzel P 
Published: October 2022

Abstract

Background
Increasing evidence suggests that FXI is an attractive target for antithrombotic therapy because it reduces thrombosis without increasing bleeding risk. Patients with decreased levels of FXI are at reduced risk of cardiovascular diseases and thromboembolic events. We have already revealed that depletion of FXI inhibits the vascular coagulation-inflammatory circuit in angiotensin II-induced arterial hypertension. However, the effect of FXI depletion on cardiac inflammation and vascular function in ischemia/reperfusion (I/R) injury is unknown.

Purpose
Using FXI-depleted mice to investigate the role of FXI in inflammation response post cardiac I/R injury.

Methods
8–12 weeks old C57BL/6J male mice were injected intraperitoneally with FXI antisense oligonucleotide (FXI ASO) or scrambled controls for a period of 2 weeks. Then we temporarily ligated the left anterior descending (LAD) for 45 minutes to induce myocardial ischemia, followed by the reperfusion for 72 hours (ischemia/reperfusion injury, IRI). Myocardial inflammation and vascular function were analyzed by flow cytometry, real-time PCR, vascular relaxation studies from isolated aortic segment in organ chamber and chemiluminescence photon counting of oxidative burst in whole blood.

Results
FXI ASO treatment reduced hepatic FXI mRNA levels and prolonged activated partial thromboplastin time. Compared to scrambled ASO injected mice, oxidative burst from whole blood and endothelial dysfunction were decreased in FXI ASO injected mice with IRI. Compared to control groups, depletion of FXI attenuated cardiac infiltration of CD45+CD11b+ cells, especially LyG-LyChigh monocytes and LyG+ neutrophils at day 3 in I/R injury. Furthermore, the expression levels of adhesion molecules and expression of pro-inflammatory cytokines, such as Vcam-1, CCL2, IL-6 and IL-1b, in ischemic myocardium were significantly decreased in the FXI depleted mice of I/R injury.

Conclusion
Our results suggest that Inhibition of FXI leads to reduction of vascular dysfunction and ROS production in I/R injury, as well as attenuation of the inflammatory response and the influx of inflammatory cells in ischemic myocardium. This indicates that FXI could be a potential target for further treatment in cardiac IRI.

Funding Acknowledgement
Type of funding sources: Public grant(s) – EU funding. Main funding source(s): TICARDIO project has received funding from the European Union's Horizon 2020 research and Innovation programme under the Marie Skłodowska-Curie grant agreement No 813409.
Nuclear accumulation of MLKL induces necroptosis in cardiomyocytes: potential implication in Doxorubicin-induced cardiotoxicity
Authors: Shimizu M , Ohwada W , Kouzu H , Sato T , Osanami A , Ogawa T , Ino S , Toda Y , Kuno A , Tanno M , Yano T 
Published: October 2022

Abstract

Background
The treatment with doxorubicin, a powerful chemotherapeutic agent, has been shown to be associated with an increased risk of lethal heart failure. Although various types of cell death pathway such as apoptosis and ferroptosis have been shown to be involved in the development of doxorubicin-induced cardiotoxicity, DIC, the involvement of necroptosis, a novel programmed necrosis induced by translocation of activated mixed lineage kinase domain-like protein, MLKL, to plasma membrane, remains unclear.

Purpose
The aim of this study was to determine whether necroptosis is involved in the development of DIC.

Methods and results
DIC was induced in C57BL/6J mice by intraperitoneal injection of doxorubicin at a dose of 10 mg/kg 3 times for a week. Eight days after the commencement of injection, echocardiographic analyses showed that left ventricular ejection fraction assessed by echocardiography was significantly lower in the doxorubicin-treated mice than in the vehicle-treated mice (44.0±13.7 vs. 70.5±3.7%), indicating the development of DIC. Immunoblot analysis showed that MLKL protein level was higher by 1.6 fold in the doxorubicin-treated mice than in the vehicle-treated mice. Interestingly, immunohistochemical analysis showed that signals of phospho-Ser345-MLKL, an activated form of MLKL, was found in the nuclei in addition to cytosol and intercalated discs of cardiomyocytes in the doxorubicin-treated mice. To get novel insight into significance of nuclear MLKL accumulation, a leucine-rich nuclear export signal (NES) spanning amino acids 280–284 of rat MLKL was identified by site-directed mutation analyses, and H9c2 cells, cultured rat cardiomyoblasts, were transfected with expression constructs for nucleus-directed MLKL (FLAG-mtNES-MLKL) or its wild type (FLAG-WT-MLKL). Percentage of FLAG-positive cells stained with Zombie Red, a fluorescent dye that is non-permeant to live cells, was higher in FLAG-mtNES-MLKL-transfected cells than in FLAG-WT-MLKL-transfected cells (80.0±3.5% vs. 6.3±1.3%, p&lt;0.05), whereas percentage of cells immunostained with cleaved caspase-3 to FLAG-positive cells was similar in the two groups. The effect of the MLKL mutant on necroptosis was attenuated by treatment with GppNHp, an inhibitor of Ran-mediated nuclear protein import.

Conclusion
Nuclear accumulation of MLKL induces necroptosis in cardiomyocytes, which may contribute to progression of DIC.

Funding Acknowledgement
Type of funding sources: None.