Cell-specific effects of Nox2 on the acute and chronic response to myocardial infarction

Very low-density lipoprotein receptor mediates triglyceride-rich lipoprotein-induced oxidative stress and insulin resistance

Obesity is associated with excess lipid deposition in nonadipose tissues, leading to increased oxidative stress and insulin resistance. Very low-density lipoprotein receptor (VLDLR), a member of the LDL receptor family, binds and increases the catabolism of triglyceride-rich lipoproteins. Although VLDLR is highly expressed in the heart, its role in obesity-associated oxidative stress and insulin resistance is unclear. Here, we used lean (wild type), genetically obese leptin-deficient (ob/ob), and leptin-VLDLR double-null (ob/ob-VLDLR-/-) mice to determine the impact of VLDLR deficiency on obesity-induced oxidative stress and insulin resistance in the heart. Although insulin sensitivity and glucose uptake were reduced in the hearts of ob/ob mice, VLDLR expression was upregulated and was associated with increased VLDL uptake and excess lipid deposition. This was accompanied by an upregulation of cardiac NADPH oxidase (Nox) expression and increased production of Nox-dependent superoxides. Silencing the VLDLR in ob/ob mice had reduced VLDL uptake and prevented excess lipid deposition in the heart, in addition to a reduction of superoxide overproduction and the normalization of insulin sensitivity and glucose uptake. In isolated cardiomyocytes, VLDLR deficiency had prevented VLDL-mediated induction of Nox activity and superoxide overproduction while improving insulin sensitivity and glucose uptake. Our findings indicate that VLDLR deficiency prevents excess lipid accumulation and moderates oxidative stress and insulin resistance in the hearts of obese mice. This effect is linked to the active role of VLDLR in VLDL uptake, which triggers a cascade of events leading to increased Nox activity, superoxide overproduction, and insulin resistance.NEW & NOTEWORTHY Obesity is associated with excess lipid deposition in muscles, which is considered as a leading cause of metabolic dysfunction and oxidative stress. Cellular uptake of lipids is regulated by several membrane receptors, among which is the very low-density lipoprotein receptor (VLDLR). This article provides information on the role of VLDLR in cardiac muscle and how its expression regulates insulin resistance and oxidative stress in the obese mouse model.

Modulation of NOX2 causes obesity-mediated atrial fibrillation

Obesity is linked to an increased risk of atrial fibrillation (AF) via increased oxidative stress. While NADPH oxidase 2 (NOX2), a major source of oxidative stress and reactive oxygen species (ROS) in the heart, predisposes to AF, the underlying mechanisms remain unclear. Here, we studied NOX2-mediated ROS production in obesity-mediated AF using Nox2-knockout mice and mature human induced pluripotent stem cell-derived atrial cardiomyocytes (hiPSC-aCMs). Diet-induced obesity (DIO) mice and hiPSC-aCMs treated with palmitic acid (PA) were infused with a NOX blocker (apocynin) and a NOX2-specific inhibitor, respectively. We showed that NOX2 inhibition normalized atrial action potential duration and abrogated obesity-mediated ion channel remodeling with reduced AF burden. Unbiased transcriptomics analysis revealed that NOX2 mediates atrial remodeling in obesity-mediated AF in DIO mice, PA-treated hiPSC-aCMs, and human atrial tissue from obese individuals by upregulation of paired-like homeodomain transcription factor 2 (PITX2). Furthermore, hiPSC-aCMs treated with hydrogen peroxide, a NOX2 surrogate, displayed increased PITX2 expression, establishing a mechanistic link between increased NOX2-mediated ROS production and modulation of PITX2. Our findings offer insights into possible mechanisms through which obesity triggers AF and support NOX2 inhibition as a potential novel prophylactic or adjunctive therapy for patients with obesity-mediated AF.

NADPH Oxidase 3: Beyond the Inner Ear

Reactive oxygen species (ROS) were formerly known as mere byproducts of metabolism with damaging effects on cellular structures. The discovery and description of NADPH oxidases (Nox) as a whole enzyme family that only produce this harmful group of molecules was surprising. After intensive research, seven Nox isoforms were discovered, described and extensively studied. Among them, the NADPH oxidase 3 is the perhaps most underrated Nox isoform, since it was firstly discovered in the inner ear. This stigma of Nox3 as "being only expressed in the inner ear" was also used by me several times. Therefore, the question arose whether this sentence is still valid or even usable. To this end, this review solely focuses on Nox3 and summarizes its discovery, the structural components, the activating and regulating factors, the expression in cells, tissues and organs, as well as the beneficial and detrimental effects of Nox3-mediated ROS production on body functions. Furthermore, the involvement of Nox3-derived ROS in diseases progression and, accordingly, as a potential target for disease treatment, will be discussed.

Redox Regulation of PTEN by Reactive Oxygen Species: Its Role in Physiological Processes

Phosphatase and tensin homolog (PTEN) is a tumor suppressor due to its ability to regulate cell survival, growth, and proliferation by downregulating the PI3K/AKT signaling pathway. In addition, PTEN plays an essential role in other physiological events associated with cell growth demands, such as ischemia-reperfusion, nerve injury, and immune responsiveness. Therefore, recently, PTEN inhibition has emerged as a potential therapeutic intervention in these situations. Increasing evidence demonstrates that reactive oxygen species (ROS), especially hydrogen peroxide (H2O2), are produced and required for the signaling in many important cellular processes under such physiological conditions. ROS have been shown to oxidize PTEN at the cysteine residue of its active site, consequently inhibiting its function. Herein, we provide an overview of studies that highlight the role of the oxidative inhibition of PTEN in physiological processes.

Raspberry polyphenols target molecular pathways of heart failure

Approximately 650,000 new cases of heart failure (HF) are diagnosed annually with a 50% five-year mortality rate. HF is characterized by reduced left ventricular (LV) ejection fraction and hypertrophy of the LV wall. The pathophysiological remodeling of the heart is mediated by increased oxidative stress and inflammation. Raspberries are rich in polyphenols which may favorably impact enzymes involved in redox homeostasis while also targeting inflammatory signaling. Thus, the objective of this study was to investigate whether raspberry polyphenols could attenuate HF. Sprague Dawley rats consumed a 10% (w/w) raspberry diet for 7 weeks. At week 3, HF was surgically induced via coronary artery ligation. Hemodynamics and morphology of the heart were assessed. Expression of cardiac proteins involved in oxidative stress, inflammation, apoptosis, and remodeling were examined, and histological analysis was conducted. Additionally, human cardiomyocytes were treated with raspberry polyphenol extract (RBPE) followed by CoCl2 to chemically induce hypoxia. Redox status, apoptosis, and mitochondrial dysfunction were measured. Raspberries attenuated reductions in cardiac function and reduced morphological changes which coincided with reduced toll-like receptor (TLR)4 signaling. Reductions in oxidative stress, apoptosis, and remodeling occurred in vivo. Incubation of cardiomyocytes with RBPE attenuated CoCl2-induced oxidative stress and apoptosis despite pronounced hypoxia-inducible factor (HIF)-1α expression. These data indicate that consumption of raspberries can reduce the underlying molecular drivers of HF; thus, leading to the observed improvements in cardiac functional capacity and morphology. This dietary strategy may be an effective alternative strategy for treating HF. However, further investigation into alternative models of HF is warranted.

Non-Coding RNAs in Cell-to-Cell Communication: Exploiting Physiological Mechanisms as Therapeutic Targets in Cardiovascular Pathologies

Cardiovascular disease, the leading cause of death worldwide, has been characterized at the molecular level by alterations in gene expression that contribute to the etiology of the disease. Such alterations have been shown to play a critical role in the development of atherosclerosis, cardiac remodeling, and age-related heart failure. Although much is now known about the cellular and molecular mechanisms in this context, the role of epigenetics in the onset of cardiovascular disease remains unclear. Epigenetics, a complex network of mechanisms that regulate gene expression independently of changes to the DNA sequence, has been highly implicated in the loss of homeostasis and the aberrant activation of a myriad of cellular pathways. More specifically, non-coding RNAs have been gaining much attention as epigenetic regulators of various pathologies. In this review, we will provide an overview of the ncRNAs involved in cell-to-cell communication in cardiovascular disease, namely atherosclerosis, cardiac remodeling, and cardiac ageing, and the potential use of epigenetic drugs as novel therapeutic targets.

Role of oxidative stress in calcific aortic valve disease and its therapeutic implications

Calcific aortic valve disease (CAVD) is the end result of active cellular processes that lead to the progressive fibrosis and calcification of aortic valve leaflets. In western populations, CAVD is a significant cause of cardiovascular morbidity and mortality, and in the absence of effective drugs, it will likely represent an increasing disease burden as populations age. As there are currently no pharmacological therapies available for preventing, treating, or slowing the development of CAVD, understanding the mechanisms underlying the initiation and progression of the disease is important for identifying novel therapeutic targets. Recent evidence has emerged of an important causative role for reactive oxygen species (ROS)-mediated oxidative stress in the pathophysiology of CAVD, inducing the differentiation of valve interstitial cells into myofibroblasts and then osteoblasts. In this review, we focus on the roles and sources of ROS driving CAVD and consider their potential as novel therapeutic targets for this debilitating condition.

An Overview of the Molecular Mechanisms Associated with Myocardial Ischemic Injury: State of the Art and Translational Perspectives

Cardiovascular disease is the leading cause of death in western countries. Among cardiovascular diseases, myocardial infarction represents a life-threatening condition predisposing to the development of heart failure. In recent decades, much effort has been invested in studying the molecular mechanisms underlying the development and progression of ischemia/reperfusion (I/R) injury and post-ischemic cardiac remodeling. These mechanisms include metabolic alterations, ROS overproduction, inflammation, autophagy deregulation and mitochondrial dysfunction. This review article discusses the most recent evidence regarding the molecular basis of myocardial ischemic injury and the new potential therapeutic interventions for boosting cardioprotection and attenuating cardiac remodeling.

Upregulation of p67phox in response to ischemia/reperfusion is cardioprotective by increasing ZIP2 expression via STAT3

While the zinc transporter ZIP2 (Slc39a2) is upregulated via STAT3 as an adaptive response to protect the heart from ischemia/reperfusion (I/R) injury, the precise mechanism underlying its upregulation remains unclear. The purpose of this study was to investigate the role of NADPH oxidase (NOX) isoform NOX2-derived ROS in the regulation of ZIP2 expression, focusing on the role of the NOX2 cytosolic factor p67^phox. Mouse hearts or H9c2 cells were subjected to I/R. Protein expression was detected with Western blotting. Infarct size was measured with TTC staining. The cardiac-specific p67^phox conditional knockout mice (p67^phox cKO) were generated by adopting the CRISPR/Cas9 system. I/R-induced upregulation of STAT3 phosphorylation and ZIP2 expression was reversed by the ROS scavenger N-acetylcysteine (NAC) and the NOX inhibitor diphenyleneiodonium (DPI). p67^phox but not NOX2 expression was increased 30 min after the onset of reperfusion, and downregulation of p67^phox by siRNA or cKO invalidated I/R-induced upregulation of STAT3 phosphorylation and ZIP2 expression. Both NAC and DPI prevented upregulation of STAT3 phosphorylation and ZIP2 expression induced by overexpression of p67^phox, whereas the STAT3 inhibitor stattic abrogated upregulation ZIP2 expression, indicating that the increase of p67^phox at reperfusion is an upstream signaling event responsible for ZIP2 upregulation via STAT3. Experiments also showed that chelation of Zn²⁺ markedly enhanced p67^phox and ZIP2 expression as well as STAT3 phosphorylation, whereas supplementation of Zn²⁺ had the opposite effects, indicating that cardiac Zn²⁺ loss upon reperfusion triggers p67^phox upregulation. Furthermore, ischemic preconditioning (IPC) upregulated ZIP2 via p67^phox, and cKO of p67^phox aggravated cardiac injury after I/R, indicating that p67^phox upregulation is cardioprotective against I/R injury. In conclusion, an increase of p67^phox expression in response to Zn²⁺ is an intrinsic adaptive response to I/R and leads to cardioprotection against I/R by upregulating ZIP2 via STAT3.

Polymeric nanoparticles in the diagnosis and treatment of myocardial infarction: Challenges and future prospects

Myocardial infarction (MI) is the leading cause of morbidity and mortality worldwide. Despite extensive efforts to provide early diagnosis and adequate treatment regimens, detection of MI still faces major limitations and pathological MI complications continue to threaten the recovery of survivors. Polymeric nanoparticles (NPs) represent novel noninvasive drug delivery systems for the diagnosis and treatment of MI and subsequent prevention of fatal heart failure. In this review, we cover the recent advances in polymeric NP-based diagnostic and therapeutic approaches for MI and their application as multifunctional theranostic tools. We also discuss the in vivo behavior and toxicity profile of polymeric NPs, their application in noninvasive imaging, passive, and active drug delivery, and use in cardiac regenerative therapy. We conclude with the challenges faced with polymeric nanosystems and suggest future efforts needed for clinical translation.

Parkinson's disease protein 7 protected against oxidative stress of myocardial infarction direct through p47phox and nicotinamide adenine dinucleotide phosphate oxidase 4

In the present study, we aimed to investigate the role and mechanism of Parkinson's disease protein 7 (Park7) in myocardial infarction (MI). The Park7 expression in the serum and tissues was down-regulated in mice with MI. Recombinant Park7 protein protected against MI-induced injury and reduced oxidative stress in mice model. Conversely, knockout Park7 increased injury of MI and promoted oxidative stress in MI mice model. In embryonic rat cardiac myoblasts H9c2 cells, over-expression of Park7 reduced reactive oxygen species (ROS)-induced oxidative stress, while down-regulation of Park7 increased ROS-induced oxidative stress. Park7 combined nicotinamide adenine dinucleotide phosphate (NADPH) oxidase cytoplasmic subunit p47phox protein had direct effect on inducing NADPH activator. The inhibition of p47phox reduced the effects of Park7 in ROS production of H₂O₂-treated H9c2 cells. The regulation of NADPH participated in the effects of Park7 on ROS production of in both MI mice model and H₂O₂-treated H9c2 cells. Our data demonstrated that Park7 protects against oxidative stress in MI model direct through p47phox and NADPH oxidase 4.

A Retinoic Acid Receptor β 2 Agonist Improves Cardiac Function in a Heart Failure Model

We previously demonstrated that the selective retinoic acid receptor (RAR) β 2 agonist AC261066 reduces oxidative stress in an ex vivo murine model of ischemia/reperfusion. We hypothesized that by decreasing oxidative stress and consequent fibrogenesis, AC261066 could attenuate the development of contractile dysfunction in post-ischemic heart failure (HF). We tested this hypothesis in vivo using an established murine model of myocardial infarction (MI), obtained by permanent occlusion of the left anterior descending coronary artery. Treating mice with AC261066 in drinking water significantly attenuated the post-MI deterioration of echocardiographic indices of cardiac function, diminished remodeling, and reduced oxidative stress, as evidenced by a decrease in malondialdehyde level and p38 mitogen-activated protein kinase expression in cardiomyocytes. The effects of AC261066 were also associated with a decrease in interstitial fibrosis, as shown by a marked reduction in collagen deposition and α-smooth muscle actin expression. In cardiac murine fibroblasts subjected to hypoxia, AC261066 reversed hypoxia-induced decreases in superoxide dismutase 2 and angiopoietin-like 4 transcriptional levels as well as the increase in NADPH oxidase 2 mRNA, demonstrating that the post-MI cardioprotective effects of AC261066 are associated with an action at the fibroblast level. Thus, AC261066 alleviates post-MI cardiac dysfunction by modulating a set of genes involved in the oxidant/antioxidant balance. These AC261066 responsive genes diminish interstitial fibrogenesis and remodeling. Since MI is a recognized major cause of HF, our data identify RARβ 2 as a potential pharmacological target in the treatment of HF. SIGNIFICANCE STATEMENT: A previous report showed that the selective retinoic acid receptor (RAR) β 2 agonist AC261066 reduces oxidative stress in an ex vivo murine model of ischemia/reperfusion. This study shows that AC261066 attenuates the development of contractile dysfunction and maladaptive remodeling in post-ischemic heart failure (HF) by modulating a set of genes involved in oxidant/antioxidant balance. Since myocardial infarction is a recognized major cause of HF, these data identify RARβ 2 as a potential pharmacological target in the treatment of HF.

Redox signaling in heart failure and therapeutic implications

Heart failure is a growing health burden worldwide characterized by alterations in excitation-contraction coupling, cardiac energetic deficit and oxidative stress. While current treatments are mostly limited to antagonization of neuroendocrine activation, more recent data suggest that also targeting metabolism may provide substantial prognostic benefit. However, although in a broad spectrum of preclinical models, oxidative stress plays a causal role for the development and progression of heart failure, no treatment that targets reactive oxygen species (ROS) directly has entered the clinical arena yet. In the heart, ROS derive from various sources, such as NADPH oxidases, xanthine oxidase, uncoupled nitric oxide synthase and mitochondria. While mitochondria are the primary source of ROS in the heart, communication between different ROS sources may be relevant for physiological signalling events as well as pathologically elevated ROS that deteriorate excitation-contraction coupling, induce hypertrophy and/or trigger cell death. Here, we review the sources of ROS in the heart, the modes of pathological activation of ROS formation as well as therapeutic approaches that may target ROS specifically in mitochondria.

Oxidative Stress Links Aging-Associated Cardiovascular Diseases and Prostatic Diseases

The incidence of chronic aging-associated diseases, especially cardiovascular and prostatic diseases, is increasing with the aging of society. Evidence indicates that cardiovascular diseases usually coexist with prostatic diseases or increase its risk, while the pathological mechanisms of these diseases are unknown. Oxidative stress plays an important role in the development of both cardiovascular and prostatic diseases. The levels of oxidative stress biomarkers are higher in patients with cardiovascular diseases, and these also contribute to the development of prostatic diseases, suggesting cardiovascular diseases may increase the risk of prostatic diseases via oxidative stress. This review summarizes the role of oxidative stress in cardiovascular and prostatic diseases and also focuses on the main shared pathways underlying these diseases, in order to provide potential prevention and treatment targets.

Corticosteroid use, myocardial injury and in-hospital cardiovascular events in patients with community-acquired pneumonia

BACKGROUND AND PURPOSE

Corticosteroids are often prescribed to community-acquired pneumonia (CAP) patients, but the relationship with major cardiovascular events (MACEs) is unclear.

EXPERIMENTAL APPROACH

541 CAP patients were recruited (334 males, mean age 71.9 ± 16.2 years). High-sensitivity troponin T (hs-cTnT) was measured at admission, during the hospital stay and at discharge. MACE occurrence was registered during a long-term follow-up.

KEY RESULTS

Overall, 318 patients (59%) showed hs-cTnT elevation >99th percentile (>0.014 μg/L). Age, heart failure and the increasing quintiles of hs-cTnT (hazard ratio [HR] 2.16, 95% confidence interval [CI] 1.82-2.58, P < .001) predicted MACEs. Among patients with hs-cTnT >0.014 μg/L at admission, 102 patients (31%) were on corticosteroids and showed lower hs-cTnT increase (P = .021), (NADPH) oxidase-2 (Nox2) activation (P = .005) and incidence of MACEs than untreated ones (HR 0.64, 95% CI 0.41-0.97, P = .038); no effect of corticosteroids on MACEs was observed in CAP patients with normal troponin. In vitro study showed that glucocorticoids have an antioxidant effect via downregulation of Nox2 activity.

CONCLUSION AND IMPLICATIONS

The study provides evidence that corticosteroid use is associated with lower increase of hs-cTnT and incidence of MACEs in CAP patients.

Macrophage p47phox regulates pressure overload-induced left ventricular remodeling by modulating IL-4/STAT6/PPARγ signaling

NADPH oxidase (Nox) mediates ROS production and contributes to cardiac remodeling. However, macrophage p47^phox, a Nox subunit regulating cardiac remodeling, is unclear. We aimed to investigate the role of macrophage p47^phox in hypertensive cardiac remodeling. Pressure-overload induced by Angiotensin II (AngII) for two weeks in young adult male p47^phox deficient (KO) mice showed aggravated cardiac dysfunction and hypertrophy as indicated from echocardiographic and histological studies in comparison with wild-type littermates (WT). Additionally, LV of AngII-infused KO mice showed augmented interstitial fibrosis, collagen deposition and, myofibroblasts compared to AngII-infused WT mice. Moreover, these changes in AngII-infused KO mice correlated well with the gene analysis of hypertrophic and fibrotic markers. Similar results were also found in the transverse aortic constriction model. Further, AngII-infused KO mice showed elevated circulating immunokines and increased LV leukocytes infiltration and CD206⁺ macrophages compared to AngII-infused WT mice. Likewise, LV of AngII-infused KO mice showed upregulated mRNA expression of anti-inflammatory/pro-fibrotic M2 macrophage markers (Ym1, Arg-1) compared to AngII-infused WT mice. AngII and IL-4 treated bone marrow-derived macrophages (BMDMs) from KO mice showed upregulated M2 macrophage markers and STAT6 phosphorylation (Y641) compared to AngII and IL-4 treated WT BMDMs. These alterations were at least partly mediated by macrophage as bone marrow transplantation from KO mice into WT mice aggravated cardiac remodeling. Mechanistically, AngII-infused KO mice showed hyperactivated IL-4/STAT6/PPARγ signaling and downregulated SOCS3 expression compared to AngII-infused WT mice. Our studies show that macrophage p47^phox limits anti-inflammatory signaling and extracellular matrix remodeling in response to pressure-overload.

Deficiency in gp91Phox (NOX2) Protects against Oxidative Stress and Cardiac Dysfunction in Iron Overloaded Mice

The role of NADPH oxidase subunit, gp91phox (NOX2) in development of oxidative stress and cardiac dysfunction due to iron (Fe)-overload was assessed. Control (C57BL/6J) and gp91phox knockout (KO) mice were treated for up to 8 weeks with Fe (2.5 mg/g/wk, i.p.) or Na-dextran; echocardiography, plasma 8-isoprostane (lipid peroxidation marker), cardiac Fe accumulation (Perl’s staining), and CD11b+ (WBCs) infiltrates were assessed. Fe caused no adverse effects on cardiac function at 3 weeks. At 6 weeks, significant declines in left ventricular (LV) ejection fraction (14.6% lower), and fractional shortening (19.6% lower) occurred in the Fe-treated control, but not in KO. Prolonging Fe treatment (8 weeks) maintained the depressed LV systolic function with a trend towards diastolic dysfunction (15.2% lower mitral valve E/A ratio) in controls but produced no impact on the KO. Fe-treatment (8 weeks) caused comparable cardiac Fe accumulation in both strains, but a 3.3-fold elevated plasma 8-isoprostane, and heightened CD11b+ staining in controls. In KO mice, lipid peroxidation and CD11b+ infiltration were 50% and 68% lower, respectively. Thus, gp91phox KO mice were significantly protected against oxidative stress, and systolic and diastolic dysfunction, supporting an important role of NOX2-mediated oxidative stress in causing cardiac dysfunction during Fe overload.

Nox2 dependent redox-regulation of Akt and ERK1/2 to promote left ventricular hypertrophy in dietary obesity of mice

BACKGROUND

A Nox2 containing NADPH oxidase (Nox2) is involved in the global oxidative stress found in dietary obesity and metabolic disorders. However, the effects of high fat diet (HFD) on cardiac Nox2 activation and signaling in left ventricular hypertrophy (LVH) remain unknown.

METHODS

Left ventricular (LV) tissues isolated from C57BL/6J wild-type (WT) and Nox2 knockout (Nox2KO) mice (11 months old, n = 6 per group) after 4 months of HFD treatment were used. Cardiomyocyte sizes were measured digitally on LV cross-sections. The levels of cardiac reactive oxygen species (ROS) production was determined using lucigenin-chemiluminescence and in situ dihydroethidium (DHE) fluorescence. The levels of Nox subunit expression and redox signaling were examined by immunoblotting and immunofluorescence.

RESULTS

In comparison to WT normal chow diet control hearts, WT HFD hearts had 1.8-fold increases in cardiomyocyte size, a sign of cardiac hypertrophy, and this was accompanied with ≥2-fold increase in the levels of ROS production, Nox2 expression and the phosphorylation of Akt and ERK1/2. Increased ROS production measured in HFD heart homogenates was inhibited to control levels by Tiron (a cell membrane permeable O₂^•-scavenger), diphenyleneiodonium (DPI, a flavohaemoprotein inhibitor) and Nox2 ds-tat (a Nox2 assembly inhibitor). However, all of these abnormalities were significantly reduced or absent in Nox2KO hearts under the same HFD.

CONCLUSIONS

Nox2 activation in response to dietary obesity and metabolic disorders plays a key role in cardiac oxidative stress, aberrant redox signaling and cardiomyocyte hypertrophy. Knockout of Nox2 protects hearts from oxidative damage associated with obesity and metabolic disorders.

Protective role of silibinin against myocardial ischemia/reperfusion injury-induced cardiac dysfunction

Silibinin is a traditional medicine and utilized for liver protection with antioxidant, anti-inflammation and anti-apoptosis properties. However, its role in myocardial I/R injury and the mechanism involved is currently unknown. In the present study, Silibinin treatment improves cardiac function and limits infarct size, and subsequently inhibits fibrotic remodeling in mice with myocardial I/R injury. Mechanistically, silibinin reduces cardiomyocytes apoptosis, attenuates mitochondrial impairment and endoplasmic reticulum (ER) stress, alleviates ROS generation, neutrophil infiltration and cytokines release. Consistently, silibinin prevents H9C2 cells from hypoxia/reperfusion-induced cell death, oxidative stress and inflammation in vitro. Furthermore, H9C2 cells treated with silibinin blocks NF-κB signaling activation by inhibiting IKKα phosphorylation, IκBα degradation and p65 NF-κB nuclear translocation during hypoxia/ reperfusion. In addition, silibinin plus BAY 11-7082 (a selected NF-κB inhibitor) do not provide incremental benefits in improving myocytes apoptosis, oxidative stress and inflammation in comparison with NF-κB signaling inhibition only. Thus, silibinin-mediated cardioprotection in myocardial I/R injury is associated with decreased apoptosis, oxidative stress and inflammatory response through deactivation of NF-κB pathway.

Corosolic acid attenuates cardiac fibrosis following myocardial infarction in mice

Corosolic acid (CRA) is a pentacyclic triterpenoid isolated from Lagerstroemia speciosa. The aim of the present study was to determine whether CRA reduces cardiac remodelling following myocardial infarction (MI) and to elucidate the underlying mechanisms. C57BL/6J mice were randomly divided into control (PBS-treated) or CRA-treated groups. After 14 days of pre-treatment, the mice were subjected to either sham surgery or permanent ligation of the left anterior descending artery. Following surgery, all animals were treated with PBS or CRA (10 or 20 mg/kg/day) for 4 weeks. After 4 weeks, echocardiographic, haemodynamic, gravimetric, histological and biochemical analyses were conducted. The results revealed that, upon MI, mice with CRA treatment exhibited decreased mortality rates, improved ventricular function and attenuated cardiac fibrosis compared with those in control mice. Furthermore, CRA treatment resulted in reduced oxidative stress, inflammation and apoptosis, as well as inhibited the transforming growth factor β1/Smad signalling pathway activation in cardiac tissue. In vitro studies further indicated that inhibition of AMP-activated protein kinase α (AMPKα) reversed the protective effect of CRA. In conclusion, the study revealed that CRA attenuated MI-induced cardiac fibrosis and dysfunction through modulation of inflammation and oxidative stress associated with AMPKα.

Celastrol Alleviates Aortic Valve Calcification Via Inhibition of NADPH Oxidase 2 in Valvular Interstitial Cells

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The reactive oxygen species–generating enzyme Nox2 is up-regulated in the leaflets of both rabbit and human with CAVD.

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Nox2 is markedly induced in cultured porcine AVICs after osteogenic stimulation. Knockdown of endogenous Nox2 substantially suppressed AVIC calcification.

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Celastrol, a natural compound capable of inhibiting Nox2 activity, significantly decreased AVIC calcification in vitro, and mitigated the severity of aortic valve fibrosis, calcification, and stenosis in a rabbit model of CAVD in vivo.

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The protective effects of celastrol may, in part, involve the inhibition of Nox2-mediated glycogen synthase kinase 3 beta/β-catenin pathway.

This study sought to investigate whether reactive oxygen species (ROS)–generating reduced nicotinamide adenine dinucleotide phosphate oxidase 2 (Nox2) contributes to calcific aortic valve disease (CAVD) or whether celastrol, a natural Nox2 inhibitor, may provide potential therapeutic target for CAVD. CAVD is an active and cellular-driven fibrocalcific process characterized by differentiation of aortic valvular interstitial cells (AVICs) toward an osteogenic-like phenotype. ROS levels increase in calcified aortic valves, while the sources of ROS and their roles in the pathogenesis of CAVD are elusive. The roles of Nox2 and the effects of celastrol were studied using cultured porcine AVICs in vitro and a rabbit CAVD model in vivo. Nox2 proteins were significantly upregulated in human aortic valves with CAVD. In vitro, Nox2 was markedly induced upon stimulation of AVICs with osteogenic medium, along with the increases in ROS production and calcium nodule formation. Celastrol significantly decreased calcium deposition of AVICs by 35%, with a reduction of ROS generation. Knockdown of endogenous Nox2 substantially suppressed AVIC calcification by 39%, the inhibitory effect being similar to celastrol treatment. Mechanistically, either celastrol treatment or knockdown of Nox2 significantly inhibited glycogen synthase kinase 3 beta/β-catenin signaling, leading to attenuation of fibrogenic and osteogenic responses of AVICs. In a rabbit CAVD model, administration of celastrol significantly reduced aortic valve ROS production, fibrosis, calcification, and severity of aortic stenosis, with less left ventricular dilatation and better preserved contractile function. Upregulation of Nox2 is critically involved in CAVD. Celastrol is effective to alleviate CAVD, likely through the inhibition of Nox2-mediated glycogen synthase kinase 3 beta/β-catenin pathway in AVICs.

NADPH oxidases and oxidase crosstalk in cardiovascular diseases: novel therapeutic targets

Reactive oxygen species (ROS)-dependent production of ROS underlies sustained oxidative stress, which has been implicated in the pathogenesis of cardiovascular diseases such as hypertension, aortic aneurysm, hypercholesterolaemia, atherosclerosis, diabetic vascular complications, cardiac ischaemia-reperfusion injury, myocardial infarction, heart failure and cardiac arrhythmias. Interactions between different oxidases or oxidase systems have been intensively investigated for their roles in inducing sustained oxidative stress. In this Review, we discuss the latest data on the pathobiology of each oxidase component, the complex crosstalk between different oxidase components and the consequences of this crosstalk in mediating cardiovascular disease processes, focusing on the central role of particular NADPH oxidase (NOX) isoforms that are activated in specific cardiovascular diseases. An improved understanding of these mechanisms might facilitate the development of novel therapeutic agents targeting these oxidase systems and their interactions, which could be effective in the prevention and treatment of cardiovascular disorders.

Increase of NADPH oxidase 3 in heart failure of hereditary cardiomyopathy

During the development of heart failure in humans and animal models, an increase in reactive oxygen species (ROS) levels was observed. However, there is no information whether this increase of ROS is associated with an increase in the density of specific isoforms of NADPH oxidases (NOXs) 1–5. The objective of this study was to verify whether the densities of NOXs 1–5 change during the development of heart failure. Using the well-known model of cardiomyopathic hamsters, the UM-X 7.1 line, a model that strongly resembles the pathology observed in humans from a morphological and functional point of view, our studies showed that, as in humans, NOXs 1–5 are present in both normal and UM-X7.1 hamster hearts. Even though the densities of NOXs 2 and 5 were unchanged, the levels of both NOXs 1 and 4 significantly decreased in UM-X7.1 hamster hearts during heart failure. These changes were accompanied with a significant increase in NOX3 level. These results suggest that, during heart failure, NOX3 plays a vital role in compensating the decrease of NOXs 1 and 4. This increase in NOX3 may also be responsible, at least in part, for the reported increase in ROS levels in heart failure.

Cysteine Glutathionylation Acts as a Redox Switch in Endothelial Cells

Oxidative post-translational modifications (oxPTM) of receptors, enzymes, ion channels and transcription factors play an important role in cell signaling. oxPTMs are a key way in which oxidative stress can influence cell behavior during diverse pathological settings such as cardiovascular diseases (CVD), cancer, neurodegeneration and inflammatory response. In addition, changes in oxPTM are likely to be ways in which low level reactive oxygen and nitrogen species (RONS) may contribute to redox signaling, exerting changes in physiological responses including angiogenesis, cardiac remodeling and embryogenesis. Among oxPTM, S-glutathionylation of reactive cysteines emerges as an important regulator of vascular homeostasis by modulating endothelial cell (EC) responses to their local redox environment. This review summarizes the latest findings of S-glutathionylated proteins in major EC pathways, and the functional consequences on vascular pathophysiology. This review highlights the diversity of molecules affected by S-glutathionylation, and the complex consequences on EC function, thereby demonstrating an intricate dual role of RONS-induced S-glutathionylation in maintaining vascular homeostasis and participating in various pathological processes.

NOX5: Molecular biology and pathophysiology

NEW FINDINGS

What is the topic of this review? This review provides a comprehensive overview of Nox5 from basic biology to human disease and highlights unique features of this Nox isoform What advances does it highlight? Major advances in Nox5 biology relate to crystallization of the molecule and new insights into the pathophysiological role of Nox5. Recent discoveries have unravelled the crystal structure of Nox5, the first Nox isoform to be crystalized. This provides new opportunities to develop drugs or small molecules targeted to Nox5 in an isoform-specific manner, possibly for therapeutic use. Moreover genome wide association studies (GWAS) identified Nox5 as a new blood pressure-associated gene and studies in mice expressing human Nox5 in a cell-specific manner have provided new information about the (patho) physiological role of Nox5 in the cardiovascular system and kidneys. Nox5 seems to be important in the regulation of vascular contraction and kidney function. In cardiovascular disease and diabetic nephropathy, Nox5 activity is increased and this is associated with increased production of reactive oxygen species and oxidative stress implicated in tissue damage.

ABSTRACT

Nicotinamide adenine dinucleotide phosphate (NADPH) oxidases (Nox), comprise seven family members (Nox1-Nox5 and dual oxidase 1 and 2) and are major producers of reactive oxygen species in mammalian cells. Reactive oxygen species are crucially involved in cell signalling and function. All Noxs share structural homology comprising six transmembrane domains with two haem-binding regions and an NADPH-binding region on the intracellular C-terminus, whereas their regulatory systems, mechanisms of activation and tissue distribution differ. This explains the diverse function of Noxs. Of the Noxs, NOX5 is unique in that rodents lack the gene, it is regulated by Ca2+ , it does not require NADPH oxidase subunits for its activation, and it is not glycosylated. NOX5 localizes in the perinuclear and endoplasmic reticulum regions of cells and traffics to the cell membrane upon activation. It is tightly regulated through numerous post-translational modifications and is activated by vasoactive agents, growth factors and pro-inflammatory cytokines. The exact pathophysiological significance of NOX5 remains unclear, but it seems to be important in the physiological regulation of sperm motility, vascular contraction and lymphocyte differentiation, and NOX5 hyperactivation has been implicated in cardiovascular disease, kidney injury and cancer. The field of NOX5 biology is still in its infancy, but with new insights into its biochemistry and cellular regulation, discovery of the NOX5 crystal structure and genome-wide association studies implicating NOX5 in disease, the time is now ripe to advance NOX5 research. This review provides a comprehensive overview of our current understanding of NOX5, from basic biology to human disease, and highlights the unique characteristics of this enigmatic Nox isoform.

Review on Chamber-Specific Differences in Right and Left Heart Reactive Oxygen Species Handling

Reactive oxygen species (ROS) exert signaling character (redox signaling), or damaging character (oxidative stress) on cardiac tissue depending on their concentration and/or reactivity. The steady state of ROS concentration is determined by the interplay between its production (mitochondrial, cytosolic, and sarcolemmal enzymes) and ROS defense enzymes (mitochondria, cytosol). Recent studies suggest that ROS regulation is different in the left and right ventricle of the heart, specifically by a different activity of superoxide dismutase (SOD). Mitochondrial ROS defense seems to be lower in right ventricular tissue compared to left ventricular tissue. In this review we summarize the current evidence for heart chamber specific differences in ROS regulation that may play a major role in an observed inability of the right ventricle to compensate for cardiac stress such as pulmonary hypertension. Based on the current knowledge regimes to increase ROS defense in right ventricular tissue should be in the focus for the development of future therapies concerning right heart failure.

Sphingolipids Signaling in Lamellipodia Formation and Enhancement of Endothelial Barrier Function

Sphingolipids, first described in the brain in 1884, are important structural components of biological membranes of all eukaryotic cells. In recent years, several lines of evidence support the critical role of sphingolipids such as sphingosine, sphingosine-1-phosphate (S1P), and ceramide as anti- or pro-inflammatory bioactive lipid mediators in a variety of human pathologies including pulmonary and vascular disorders. Among the sphingolipids, S1P is a naturally occurring agonist that exhibits potent barrier enhancing property in the endothelium by signaling via G protein-coupled S1P1 receptor. S1P, S1P analogs, and other barrier enhancing agents such as HGF, oxidized phospholipids, and statins also utilize the S1P/S1P1 signaling pathway to generate membrane protrusions or lamellipodia, which have been implicated in resealing of endothelial gaps and maintenance of barrier integrity. A better understanding of sphingolipids mediated regulation of lamellipodia formation and barrier enhancement of the endothelium will be critical for the development of sphingolipid-based therapies to alleviate pulmonary disorders such as sepsis-, radiation-, and mechanical ventilation-induced acute lung injury.

Linagliptin improved myocardial function recovery in rat hearts after a prolonged hypothermic preservation

AIMS

To determine whether linagliptin, a dipeptidyl peptidase 4 inhibitor, can promote the recovery of cardiac function after hypothermic preservation.

MAIN METHODS

Rat hearts were preserved in cold Celsior solution with or without linagliptin for 9 h. Cardiac function was evaluated at 60 min of reperfusion after hypothermic preservation. Cardiac mitochondrial morphology was observed using transmission electron microscope. The expression of dynamin-related protein 1 (Drp1), NADPH oxidase 2 (NOX2), calmodulin-dependent protein kinase II (CaMKII) were detected using Western blot.

KEY FINDINGS

Compared with Celsior group, supplement of Celsior solution with linagliptin (0.25-0.75 nM) could significantly prevent hypothermic preservation-induced cardiac dysfunction. The expression of NOX2 protein, ROS level and MDA content in cardium were increased after hypothermic preservation, which was inhibited by linagliptin. Although the mitofusin1, 2, optic atrophy type 1, and total Drp1 expression in myocardium did not change, the level of p-Drp1 S616 and mitochondrial Drp1 were enhanced after hypothermic preservation. Linagliptin supplement could inhibit the hypothermic preservation-induced increase in p-Drp1 S616 and mitochondrial Drp1 protein, and mitigate the mitochondrial fragmentation. Level of p-CaMKII protein enhanced after hypothermic preservation, which could be prevented by linagliptin or a NOX2 inhibitor Phox-I2. Both Phox-I2 and a CaMKII inhibitor KN-93 could reduce the hypothermic preservation-induced increase in p-Drp1 S616 and mitochondrial Drp1 protein.

SIGNIFICANCE

Supplement Celsior solution with linagliptin could improve cardiac function recovery in 9-h hypothermic preserved rat hearts. The cardioprotective effect of linagliptin might be due to the inhibition of Drp1 phosphorylation and mitochondrial translocation by preventing NOX2-mediated CaMKII activation.

Protection by Inhaled Hydrogen Therapy in a Rat Model of Acute Lung Injury can be Tracked in vivo Using Molecular Imaging

Inhaled hydrogen gas (H2) provides protection in rat models of human acute lung injury (ALI). We previously reported that biomarker imaging can detect oxidative stress and endothelial cell death in vivo in a rat model of ALI. Our objective was to evaluate the ability of Tc-hexamethylpropyleneamineoxime (HMPAO) and Tc-duramycin to track the effectiveness of H2 therapy in vivo in the hyperoxia rat model of ALI. Rats were exposed to room air (normoxia), 98% O2 + 2% N2 (hyperoxia) or 98% O2 + 2% H2 (hyperoxia+H2) for up to 60 h. In vivo scintigraphy images were acquired following injection of Tc-HMPAO or Tc-duramycin. For hyperoxia rats, Tc-HMPAO and Tc-duramycin lung uptake increased in a time-dependent manner, reaching a maximum increase of 270% and 150% at 60 h, respectively. These increases were reduced to 120% and 70%, respectively, in hyperoxia+H2 rats. Hyperoxia exposure increased glutathione content in lung homogenate (36%) more than hyperoxia+H2 (21%), consistent with increases measured in Tc-HMPAO lung uptake. In 60-h hyperoxia rats, pleural effusion, which was undetectable in normoxia rats, averaged 9.3 gram/rat, and lung tissue 3-nitrotyrosine expression increased by 790%. Increases were reduced by 69% and 59%, respectively, in 60-h hyperoxia+H2 rats. This study detects and tracks the anti-oxidant and anti-apoptotic properties of H2 therapy in vivo after as early as 24 h of hyperoxia exposure. The results suggest the potential utility of these SPECT biomarkers for in vivo assessment of key cellular pathways in the pathogenesis of ALI and for monitoring responses to therapies.

Dunye Guanxinning Improves Acute Myocardial Ischemia-Reperfusion Injury by Inhibiting Neutrophil Infiltration and Caspase-1 Activity

Acute myocardial infarction is the most serious manifestation of cardiovascular disease, and it is a life-threatening condition. Dunye Guanxinning (DG) is a protective traditional Chinese patent herbal medicine with high clinical efficacy and suitable for the treatment of myocardial infarction. However, the mechanism through which it is beneficial is unclear. In this study, we hypothesized that DG improves acute myocardial ischemia-reperfusion injury by inhibiting neutrophil infiltration and caspase-1 activity. We found that DG administration decreased infarct size and cardiomyocyte apoptosis and improved left ventricular ejection fraction, fractional shortening, end-systolic volume index, end-systolic diameter, and carotid arterial blood flow output in rats. DG administration also improved hemorheological parameters, myocardial damage biomarkers, and oxidative stress indexes. The findings showed that DG administration inhibited neutrophil infiltration and reduced the serum interleukin-1 beta (IL-1β) level and myocardial IL-1β maturation. Moreover, DG administration inhibited caspase-1 activity and activated adenosine monophosphate-activated protein kinase (AMPK) phosphorylation in rat hearts. These results suggested that DG administration inhibits inflammasome activity and IL-1β release through the AMPK pathway. Our findings support the clinical efficacy of DG and partially reveal its mechanism, which is beneficial for understanding the therapeutic effects of this protective traditional Chinese patent drug.

Maternal diabetes up-regulates NOX2 and enhances myocardial ischaemia/reperfusion injury in adult offspring

Offspring of diabetic mothers are at risk of cardiovascular diseases in adulthood. However, the underlying molecular mechanisms are not clear. We hypothesize that prenatal exposure to maternal diabetes up‐regulates myocardial NOX2 expression and enhances ischaemia/reperfusion (I/R) injury in the adult offspring. Maternal diabetes was induced in C57BL/6 mice by streptozotocin. Glucose‐tolerant adult offspring of diabetic mothers and normal controls were subjected to myocardial I/R injury. Vascular endothelial growth factor (VEGF) expression, ROS generation, myocardial apoptosis and infarct size were assessed. The VEGF‐Akt (protein kinase B)‐mammalian target of rapamycin (mTOR)‐NOX2 signalling pathway was also studied in cultured cardiomyocytes in response to high glucose level. In the hearts of adult offspring from diabetic mothers, increases were observed in VEGF expression, NOX2 protein levels and both Akt and mTOR phosphorylation levels as compared to the offspring of control mothers. After I/R, ROS generation, myocardial apoptosis and infarct size were all significantly higher in the offspring of diabetic mothers relative to offspring of control mothers, and these differences were diminished by in vivo treatment with the NADPH oxidase inhibitor apocynin. In cultured cardiomyocytes, high glucose increased mTOR phosphorylation, which was inhibited by the PI3 kinase inhibitor LY294002. Notably, high glucose‐induced NOX2 protein expression and ROS production were inhibited by rapamycin. In conclusion, maternal diabetes promotes VEGF‐Akt‐mTOR‐NOX2 signalling and enhances myocardial I/R injury in the adult offspring. Increased ROS production from NOX2 is a possible molecular mechanism responsible for developmental origins of cardiovascular disease in offspring of diabetic mothers.

Cardiomyocytes Sense Matrix Rigidity through a Combination of Muscle and Non-muscle Myosin Contractions

Mechanical properties are cues for many biological processes in health or disease. In the heart, changes to the extracellular matrix composition and cross-linking result in stiffening of the cellular microenvironment during development. Moreover, myocardial infarction and cardiomyopathies lead to fibrosis and a stiffer environment, affecting cardiomyocyte behavior. Here, we identify that single cardiomyocyte adhesions sense simultaneous (fast oscillating) cardiac and (slow) non-muscle myosin contractions. Together, these lead to oscillating tension on the mechanosensitive adaptor protein talin on substrates with a stiffness of healthy adult heart tissue, compared with no tension on embryonic heart stiffness and continuous stretching on fibrotic stiffness. Moreover, we show that activation of PKC leads to the induction of cardiomyocyte hypertrophy in a stiffness-dependent way, through activation of non-muscle myosin. Finally, PKC and non-muscle myosin are upregulated at the costameres in heart disease, indicating aberrant mechanosensing as a contributing factor to long-term remodeling and heart failure.

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Talin in cardiomyocytes is unstretched, cyclically stretched, or continuously stretched

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Talin stretching depends on stiffness, myofibrillar tension, and non-myofibrillar tension

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Non-myofibrillar contractility requires PKC, Src, FHOD1, and non-muscle myosin

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PKC and non-muscle myosin activity are enhanced in cardiac disease

Mechanisms contributing to cardiac remodelling

Cardiac remodelling is classified as physiological (in response to growth, exercise and pregnancy) or pathological (in response to inflammation, ischaemia, ischaemia/reperfusion (I/R) injury, biomechanical stress, excess neurohormonal activation and excess afterload). Physiological remodelling of the heart is characterized by a fine-tuned and orchestrated process of beneficial adaptations. Pathological cardiac remodelling is the process of structural and functional changes in the left ventricle (LV) in response to internal or external cardiovascular damage or influence by pathogenic risk factors, and is a precursor of clinical heart failure (HF). Pathological remodelling is associated with fibrosis, inflammation and cellular dysfunction (e.g. abnormal cardiomyocyte/non-cardiomyocyte interactions, oxidative stress, endoplasmic reticulum (ER) stress, autophagy alterations, impairment of metabolism and signalling pathways), leading to HF. This review describes the key molecular and cellular responses involved in pathological cardiac remodelling.

The Impact of Environmental Factors in Influencing Epigenetics Related to Oxidative States in the Cardiovascular System

Oxidative states exert a significant influence on a wide range of biological and molecular processes and functions. When their balance is shifted towards enhanced amounts of free radicals, pathological phenomena can occur, as the generation of reactive oxygen species (ROS) in tissue microenvironment or in the systemic circulation can be detrimental. Epidemic chronic diseases of western societies, such as cardiovascular disease, obesity, and diabetes correlate with the imbalance of redox homeostasis. Current advances in our understanding of epigenetics have revealed a parallel scenario showing the influence of oxidative stress as a major regulator of epigenetic gene regulation via modification of DNA methylation, histones, and microRNAs. This has provided both the biological link and a potential molecular explanation between oxidative stress and cardiovascular/metabolic phenomena. Accordingly, in this review, we will provide current insights on the physiological and pathological impact of changes in oxidative states on cardiovascular disorders, by specifically focusing on the influence of epigenetic regulation. A special emphasis will highlight the effect on epigenetic regulation of human's current life habits, external and environmental factors, including food intake, tobacco, air pollution, and antioxidant-based approaches. Additionally, the strategy to quantify oxidative states in humans in order to determine which biological marker could best match a subject's profile will be discussed.

Redox regulation of ischemic limb neovascularization - What we have learned from animal studies

Mouse hindlimb ischemia has been widely used as a model to study peripheral artery disease. Genetic modulation of the enzymatic source of oxidants or components of the antioxidant system reveal that physiological levels of oxidants are essential to promote the process of arteriogenesis and angiogenesis after femoral artery occlusion, although mice with diabetes or atherosclerosis may have higher deleterious levels of oxidants. Therefore, fine control of oxidants is required to stimulate vascularization in the limb muscle. Oxidants transduce cellular signaling through oxidative modifications of redox sensitive cysteine thiols. Of particular importance, the reversible modification with abundant glutathione, called S-glutathionylation (or GSH adducts), is relatively stable and alters protein function including signaling, transcription, and cytoskeletal arrangement. Glutaredoxin-1 (Glrx) is an enzyme which catalyzes reversal of GSH adducts, and does not scavenge oxidants itself. Glrx may control redox signaling under fluctuation of oxidants levels. In ischemic muscle increased GSH adducts through Glrx deletion improves in vivo limb revascularization, indicating endogenous Glrx has anti-angiogenic roles. In accordance, Glrx overexpression attenuates VEGF signaling in vitro and ischemic vascularization in vivo. There are several Glrx targets including HIF-1α which may contribute to inhibition of vascularization by reducing GSH adducts. These animal studies provide a caution that excess antioxidants may be counter-productive for treatment of ischemic limbs, and highlights Glrx as a potential therapeutic target to improve ischemic limb vascularization.

High-throughput screening identifies microRNAs that target Nox2 and improve function after acute myocardial infarction

Myocardial infarction (MI) is the most common cause of heart failure. Excessive production of ROS plays a key role in the pathogenesis of cardiac remodeling after MI. NADPH with NADPH oxidase (Nox)2 as the catalytic subunit is a major source of superoxide production, and expression is significantly increased in the infarcted myocardium, especially by infiltrating macrophages. While microRNAs (miRNAs) are potent regulators of gene expression and play an important role in heart disease, there still lacks efficient ways to identify miRNAs that target important pathological genes for treating MI. Thus, the overall objective was to establish a miRNA screening and delivery system for improving heart function after MI using Nox2 as a critical target. With the use of the miRNA-target screening system composed of a self-assembled cell microarray (SAMcell), three miRNAs, miR-106b, miR-148b, and miR-204, were identified that could regulate Nox2 expression and its downstream products in both human and mouse macrophages. Each of these miRNAs were encapsulated into polyketal (PK3) nanoparticles that could effectively deliver miRNAs into macrophages. Both in vitro and in vivo studies in mice confirmed that PK3-miRNAs particles could inhibit Nox2 expression and activity and significantly improve infarct size and acute cardiac function after MI. In conclusion, our results show that miR-106b, miR-148b, and miR-204 were able to improve heart function after myocardial infarction in mice by targeting Nox2 and possibly altering inflammatory cytokine production. This screening system and delivery method could have broader implications for miRNA-mediated therapeutics for cardiovascular and other diseases.NEW & NOTEWORTHY NADPH oxidase (Nox)2 is a promising target for treating cardiovascular disease, but there are no specific inhibitors. Finding endogenous signals that can target Nox2 and other inflammatory molecules is of great interest. In this study, we used high-throughput screening to identify microRNAs that target Nox2 and improve cardiac function after infarction.