Vitamin C as Scavenger of Reactive Oxygen Species during Healing after Myocardial Infarction.

Currently, coronary artery bypass and reperfusion therapies are considered the gold standard in long-term treatments to restore heart function after acute myocardial infarction. As a drawback of these restoring strategies, reperfusion after an ischemic insult and sudden oxygen exposure lead to the exacerbated synthesis of additional reactive oxidative species and the persistence of increased oxidation levels. Attempts based on antioxidant treatment have failed to achieve an effective therapy for cardiovascular disease patients. The controversial use of vitamin C as an antioxidant in clinical practice is comprehensively systematized and discussed in this review. The dose-dependent adsorption and release kinetics mechanism of vitamin C is complex; however, this review may provide a holistic perspective on its potential as a preventive supplement and/or for combined precise and targeted therapeutics in cardiovascular management therapy.

Pro-oxidative priming but maintained cardiac function in a broad spectrum of murine models of chronic kidney disease.

AIMS: Patients with chronic kidney disease (CKD) have an increased risk of cardiovascular events and exhibit myocardial changes including left ventricular (LV) hypertrophy and fibrosis, overall referred to as 'uremic cardiomyopathy'. Although different CKD animal models have been studied for cardiac effects, lack of consistent reporting on cardiac function and pathology complicates clear comparison of these models. Therefore, this study aimed at a systematic and comprehensive comparison of cardiac function and cardiac pathophysiological characteristics in eight different CKD models and mouse strains, with a main focus on adenine-induced CKD. METHODS AND RESULTS: CKD of different severity and duration was induced by subtotal nephrectomy or adenine-rich diet in various strains (C57BL/6J, C57BL/6 N, hyperlipidemic C57BL/6J ApoE-/-, 129/Sv), followed by the analysis of kidney function and morphology, blood pressure, cardiac function, cardiac hypertrophy, fibrosis, myocardial calcification and inflammation using functional, histological and molecular techniques, including cardiac gene expression profiling supplemented by oxidative stress analysis. Intriguingly, despite uremia of variable degree, neither cardiac dysfunction, hypertrophy nor interstitial fibrosis were observed. However, already moderate CKD altered cardiac oxidative stress responses and enhanced oxidative stress markers in each mouse strain, with cardiac RNA sequencing revealing activation of oxidative stress signaling as well as anti-inflammatory feedback responses. CONCLUSION: This study considerably expands the knowledge on strain- and protocol-specific differences in the field of cardiorenal research and reveals that several weeks of at least moderate experimental CKD increase oxidative stress responses in the heart in a broad spectrum of mouse models. However, this was insufficient to induce relevant systolic or diastolic dysfunction, suggesting that additional "hits" are required to induce uremic cardiomyopathy. TRANSLATIONAL PERSPECTIVE: Patients with chronic kidney disease (CKD) have an increased risk of cardiovascular adverse events and exhibit myocardial changes, overall referred to as 'uremic cardiomyopathy'. We revealed that CKD increases cardiac oxidative stress responses in the heart. Nonetheless, several weeks of at least moderate experimental CKD do not necessarily trigger cardiac dysfunction and remodeling, suggesting that additional "hits" are required to induce uremic cardiomyopathy in the clinical setting. Whether the altered cardiac oxidative stress balance in CKD may increase the risk and extent of cardiovascular damage upon additional cardiovascular risk factors and/or events will be addressed in future studies.

Phosphatidylserine Supplementation as a Novel Strategy for Reducing Myocardial Infarct Size and Preventing Adverse Left Ventricular Remodeling.

Phosphatidylserines are known to sustain skeletal muscle activity during intense activity or hypoxic conditions, as well as preserve neurocognitive function in older patients. Our previous studies pointed out a potential cardioprotective role of phosphatidylserine in heart ischemia. Therefore, we investigated the effects of phosphatidylserine oral supplementation in a mouse model of acute myocardial infarction (AMI). We found out that phosphatidylserine increases, significantly, the cardiomyocyte survival by 50% in an acute model of myocardial ischemia-reperfusion. Similar, phosphatidylserine reduced significantly the infarcted size by 30% and improved heart function by 25% in a chronic model of AMI. The main responsible mechanism seems to be up-regulation of protein kinase C epsilon (PKC-ε), the main player of cardio-protection during pre-conditioning. Interestingly, if the phosphatidylserine supplementation is started before induction of AMI, but not after, it selectively inhibits neutrophil's activation, such as Interleukin 1 beta (IL-1ß) expression, without affecting the healing and fibrosis. Thus, phosphatidylserine supplementation may represent a simple way to activate a pre-conditioning mechanism and may be a promising novel strategy to reduce infarct size following AMI and to prevent myocardial injury during myocardial infarction or cardiac surgery. Due to the minimal adverse effects, further investigation in large animals or in human are soon possible to establish the exact role of phosphatidylserine in cardiac diseases.

Influence of Vitamin C on Antioxidant Capacity of In Vitro Perfused Porcine Kidneys.

Systemic and localized ischemia and reperfusion injury remain clinically relevant issues after organ transplantation and contribute to organ dysfunctions, among which acute kidney injury is one of the most common. An in vitro test-circuit for normothermic perfusion of porcine kidneys after warm ischemia was used to investigate the antioxidant properties of vitamin C during reperfusion. Vitamin C is known to enhance microcirculation, reduce endothelial permeability, prevent apoptosis, and reduce inflammatory reactions. Based on current evidence about the pleiotropic effects of vitamin C, we hypothesize that the antioxidant properties of vitamin C might provide organ-protection and improve the kidney graft function in this model of ischemia and reperfusion. METHODS: 10 porcine kidneys from 5 Landrace pigs were perfused in vitro for 6 h. For each experiment, both kidneys of one animal were perfused simultaneously with a 1:1 mixture of autologous blood and modified Ringer's solution at 38 °C and 75 mmHg continuous perfusion pressure. One kidney was treated with a 500 mg bolus injection of vitamin C into the perfusate, followed by continuous infusion of 60 mg/h vitamin C. In the control test circuit, an equal volume of Ringer's solution was administered as a placebo. Perfusate samples were withdrawn at distinct points in time during 6 h of perfusion for blood gas analyses as well as measurement of serum chemistry, oxidative stress and antioxidant capacity. Hemodynamic parameters and urine excretion were monitored continuously. Histological samples were analyzed to detect tubular- and glomerular-injury. RESULTS: vitamin C administration to the perfusate significantly reduced oxidative stress (49.8 ± 16.2 vs. 118.6 ± 23.1 mV; p = 0.002) after 6 h perfusion, and increased the antioxidant capacity, leading to red blood cell protection and increased hemoglobin concentrations (5.1 ± 0.2 vs. 3.9 ± 0.6 g/dL; p = 0.02) in contrast to placebo treatment. Kidney function was not different between the groups (creatinine clearance vit C: 2.5 ± 2.1 vs. placebo: 0.5 ± 0.2 mL/min/100 g; p = 0.9). Hypernatremia (187.8 ± 4.7 vs. 176.4 ± 5.7 mmol/L; p = 0.03), and a lower, but not significant decreased fractional sodium excretion (7.9 ± 2 vs. 27.7 ± 15.3%; p = 0.2) were observed in the vitamin C group. Histological analysis did not show differences in tubular- and glomerular injury between the groups. CONCLUSION: Vitamin C treatment increased the antioxidant capacity of in vitro perfused kidney grafts, reduced oxidative stress, preserved red blood cells as oxygen carrier in the perfusate, but did not improve clinically relevant parameters like kidney function or attenuate kidney damage. Nevertheless, due to its antioxidative properties vitamin C might be a beneficial supplement to clinical kidney graft perfusion protocols.

FURIN Inhibition Reduces Vascular Remodeling and Atherosclerotic Lesion Progression in Mice.

Objective- Atherosclerotic coronary artery disease is the leading cause of death worldwide, and current treatment options are insufficient. Using systems-level network cluster analyses on a large coronary artery disease case-control cohort, we previously identified PCSK3 (proprotein convertase subtilisin/kexin family member 3; FURIN) as a member of several coronary artery disease-associated pathways. Thus, our objective is to determine the role of FURIN in atherosclerosis. Approach and Results- In vitro, FURIN inhibitor treatment resulted in reduced monocyte migration and reduced macrophage and vascular endothelial cell inflammatory and cytokine gene expression. In vivo, administration of an irreversible inhibitor of FURIN, α-1-PDX (α1-antitrypsin Portland), to hyperlipidemic Ldlr-/- mice resulted in lower atherosclerotic lesion area and a specific reduction in severe lesions. Significantly lower lesional macrophage and collagen area, as well as systemic inflammatory markers, were observed. MMP2 (matrix metallopeptidase 2), an effector of endothelial function and atherosclerotic lesion progression, and a FURIN substrate was significantly reduced in the aorta of inhibitor-treated mice. To determine FURIN's role in vascular endothelial function, we administered α-1-PDX to Apoe-/- mice harboring a wire injury in the common carotid artery. We observed significantly decreased carotid intimal thickness and lower plaque cellularity, smooth muscle cell, macrophage, and inflammatory marker content, suggesting protection against vascular remodeling. Overexpression of FURIN in this model resulted in a significant 67% increase in intimal plaque thickness, confirming that FURIN levels directly correlate with atherosclerosis. Conclusions- We show that systemic inhibition of FURIN in mice decreases vascular remodeling and atherosclerosis. FURIN-mediated modulation of MMP2 activity may contribute to the atheroprotection observed in these mice.

Blocking CCL5-CXCL4 heteromerization preserves heart function after myocardial infarction by attenuating leukocyte recruitment and NETosis.

Myocardial infarction (MI) is a major cause of death in Western countries and finding new strategies for its prevention and treatment is thus of high priority. In a previous study, we have demonstrated a pathophysiologic relevance for the heterophilic interaction of CCL5 and CXCL4 in the progression of atherosclerosis. A specifically designed compound (MKEY) to block this CCL5-CXCR4 interaction is investigated as a potential therapeutic in a model of myocardial ischemia/reperfusion (I/R) damage. 8 week-old male C57BL/6 mice were intravenously treated with MKEY or scrambled control (sMKEY) from 1 day before, until up to 7 days after I/R. By using echocardiography and intraventricular pressure measurements, MKEY treatment resulted in a significant decrease in infarction size and preserved heart function as compared to sMKEY-treated animals. Moreover, MKEY treatment significantly reduced the inflammatory reaction following I/R, as revealed by specific staining for neutrophils and monocyte/macrophages. Interestingly, MKEY treatment led to a significant reduction of citrullinated histone 3 in the infarcted tissue, showing that MKEY can prevent neutrophil extracellular trap formation in vivo. Disrupting chemokine heterodimers during myocardial I/R might have clinical benefits, preserving the therapeutic benefit of blocking specific chemokines, and in addition, reducing the inflammatory side effects maintaining normal immune defence.

Caffeine enhances endothelial repair by an AMPK-dependent mechanism.

OBJECTIVE: Migratory capacity of endothelial progenitor cells (EPCs) and mature endothelial cells (ECs) is a key prerequisite for endothelial repair after denuding injury or endothelial damage. METHODS AND RESULTS: We demonstrate that caffeine in physiologically relevant concentrations (50 to 100 micromol/L) induces migration of human EPCs as well as mature ECs. In patients with coronary artery disease (CAD), caffeinated coffee increased caffeine serum concentration from 2 micromol/L to 23 micromol/L, coinciding with a significant increase in migratory activity of patient-derived EPCs. Decaffeinated coffee neither affected caffeine serum levels nor migratory capacity of EPCs. Treatment with caffeine for 7 to 10 days in a mouse-model improved endothelial repair after denudation of the carotid artery. The enhancement of reendothelialization by caffeine was significantly reduced in AMPK knockout mice compared to wild-type animals. Transplantation of wild-type and AMPK(-/-) bone marrow into wild-type mice revealed no difference in caffeine challenged reendothelialization. ECs which were depleted of mitochondrial DNA did not migrate when challenged with caffeine, suggesting a potential role for mitochondria in caffeine-dependent migration. CONCLUSIONS: These results provide evidence that caffeine enhances endothelial cell migration and reendothelialization in part through an AMPK-dependent mechanism, suggesting a beneficial role for caffeine in endothelial repair.

Indium-111 oxine labelling affects the cellular integrity of haematopoietic progenitor cells.

PURPOSE: Cell-based therapy by transplantation of progenitor cells has emerged as a promising development for organ repair, but non-invasive imaging approaches are required to monitor the fate of transplanted cells. Radioactive labelling with (111)In-oxine has been used in preclinical trials. This study aimed to validate (111)In-oxine labelling and subsequent in vivo and ex vivo detection of haematopoietic progenitor cells. METHODS: Murine haematopoietic progenitor cells (10(6), FDCPmix) were labelled with 0.1 MBq (low dose) or 1.0 MBq (high dose) (111)In-oxine and compared with unlabelled controls. Cellular retention of (111)In, viability and proliferation were determined up to 48 h after labelling. Labelled cells were injected into the cavity of the left or right cardiac ventricle in mice. Scintigraphic images were acquired 24 h later. Organ samples were harvested to determine the tissue-specific activity. RESULTS: Labelling efficiency was 75 +/- 14%. Cellular retention of incorporated (111)In after 48 h was 18 +/- 4%. Percentage viability after 48 h was 90 +/- 1% (control), 58 +/- 7% (low dose) and 48 +/- 8% (high dose) (p<0.0001). Numbers of viable cells after 48 h (normalised to 0 h) were 249 +/- 51% (control), 42 +/- 8% (low dose) and 32 +/- 5% (high dose) (p<0.0001). Cells accumulated in the spleen (86.6 +/- 27.0% ID/g), bone marrow (59.1 +/- 16.1% ID/g) and liver (30.3 +/- 9.5% ID/g) after left ventricular injection, whereas most of the cells were detected in the lungs (42.4 +/- 21.8% ID/g) after right ventricular injection. CONCLUSION: Radiolabelling of haematopoietic progenitor cells with (111)In-oxine is feasible, with high labelling efficiency but restricted stability. The integrity of labelled cells is significantly affected, with substantially reduced viability and proliferation and limited migration after systemic transfusion.

HMG-CoA reductase inhibitor simvastatin profoundly improves survival in a murine model of sepsis.

BACKGROUND: HMG-CoA reductase inhibitors, such as simvastatin, have been shown to exhibit pronounced immunomodulatory effects independent of lipid lowering but to date have not been used to treat severe inflammatory disease such as sepsis. We thus approached the question of whether treatment with simvastatin might improve cardiovascular function and survival in sepsis. METHODS AND RESULTS: Mice treated with simvastatin and rendered septic by cecal ligation and perforation (CLP) show a mean survival time close to 4 times the value found in untreated mice. This dramatic improvement is based on a complete preservation of cardiac function and hemodynamic status, which are severely impaired in untreated CLP mice [eg, 20 hours after CLP, cardiac output declined from 1.24+/-0.09 to 0.87+/-0.11 mL x min(-1) x g(-1) in untreated mice (P<0.005; n=12), while remaining unaltered (1.21+/-0.08 mL x min(-1) x g(-1) at baseline and 1.15+/-0.1 mL x min(-1) x g(-1) 20 hours after CLP, P=NS, n=12) in CLP mice treated with simvastatin]. Untreated CLP mice remained refractory to beta-stimulation, whereas the responsiveness to dobutamine was restored by treatment with simvastatin. Susceptibility of coronary flow to endothelial nitric oxide synthase (eNOS) stimulation by bradykinin was close to 3 times as pronounced in untreated CLP mice as in untreated sham-operated mice, indicating a high level of eNOS activation secondary to sepsis. In addition, treatment with simvastatin reversed inflammatory alterations in CLP mice, namely, increased monocyte adhesion to endothelium. CONCLUSIONS: Simvastatin, which is well established in the treatment of lipid disorders and coronary artery disease, might have the additional potential of being an effective agent in sepsis treatment.