Exploiting the Pleiotropic Antioxidant Effects of Established Drugs in Cardiovascular Disease

Endothelial dysfunction, platelet hyperactivity, hypertension, and the metabolic syndrome: molecular insights and combating strategies

Metabolic syndrome (MetS) is a multifaceted condition that increases the possibility of developing atherosclerotic cardiovascular disease. MetS includes obesity, hypertension, dyslipidemia, hyperglycemia, endothelial dysfunction, and platelet hyperactivity. There is a concerning rise in the occurrence and frequency of MetS globally. The rising incidence and severity of MetS need a proactive, multipronged strategy for identifying and treating those affected. For many MetS patients, achieving recommended goals for healthy fat intake, blood pressure control, and blood glucose management may require a combination of medicine therapy, lifestyles, nutraceuticals, and others. However, it is essential to note that lifestyle modification should be the first-line therapy for MetS. In addition, MetS requires pharmacological, nutraceutical, or other interventions. This review aimed to bring together the etiology, molecular mechanisms, and dietary strategies to combat hypertension, endothelial dysfunction, and platelet dysfunction in individuals with MetS.

Role of CD40(L)-TRAF signaling in inflammation and resolution—a double-edged sword

Cardiovascular diseases (CVD) and cardiovascular risk factors are the leading cause of death in the world today. According to the Global Burden of Disease Study, hypertension together with ischemic heart and cerebrovascular diseases is responsible for approximately 40% of all deaths worldwide. The major pathomechanism underlying almost all CVD is atherosclerosis, an inflammatory disorder of the vascular system. Recent large-scale clinical trials demonstrated that inflammation itself is an independent cardiovascular risk factor. Specific anti-inflammatory therapy could decrease cardiovascular mortality in patients with atherosclerosis (increased markers of inflammation). Inflammation, however, can also be beneficial by conferring so-called resolution, a process that contributes to clearing damaged tissue from cell debris upon cell death and thereby represents an essential step for recovery from, e.g., ischemia/reperfusion damage. Based on these considerations, the present review highlights features of the detrimental inflammatory reactions as well as of the beneficial process of immune cell-triggered resolution. In this context, we discuss the polarization of macrophages to either M1 or M2 phenotype and critically assess the role of the CD40L-CD40-TRAF signaling cascade in atherosclerosis and its potential link to resolution. As CD40L can bind to different cellular receptors, it can initiate a broad range of inflammatory processes that may be detrimental or beneficial. Likewise, the signaling of CD40L downstream of CD40 is mainly determined by activation of TRAF1-6 pathways that again can be detrimental or beneficial. Accordingly, CD40(L)-based therapies may be Janus-faced and require sophisticated fine-tuning in order to promote cardioprotection.

Repositioning Linagliptin for the Mitigation of Cadmium-Induced Testicular Dysfunction in Rats: Targeting HMGB1/TLR4/NLRP3 Axis and Autophagy

Cadmium, a ubiquitous environmental toxicant, disrupts testicular function and fertility. The dipeptidyl peptidase-4 inhibitor linagliptin has shown pronounced anti-inflammatory and anti-apoptotic features; however, its effects against cadmium-evoked testicular impairment have not been examined. Herein, the present study investigated targeting inflammation, apoptosis, and autophagy by linagliptin for potential modulation of cadmium-induced testicular dysfunction in rats. After 60 days of cadmium chloride administration (5 mg/kg/day, by gavage), testes, epididymis, and blood were collected for analysis. The present findings revealed that linagliptin improved the histopathological lesions, including spermatogenesis impairment and germ cell loss. Moreover, it improved sperm count/motility and serum testosterone. The favorable effects of linagliptin were mediated by curbing testicular inflammation seen by dampening of HMGB1/TLR4 pathway and associated lowering of nuclear NF-κBp65. In tandem, linagliptin suppressed the activation of NLRP3 inflammasome/caspase 1 axis with consequent lowering of the pro-inflammatory IL-1β and IL-18. Jointly, linagliptin attenuated testicular apoptotic responses seen by Bax downregulation, Bcl-2 upregulation, and suppressed caspase 3 activity. With respect to autophagy, linagliptin enhanced the testicular autophagy flux seen by lowered accumulation of p62 SQSTM1 alongside upregulation of Beclin 1. The observed autophagy stimulation was associated with elevated AMPK (Ser487) phosphorylation and lowered mTOR (Ser2448) phosphorylation, indicating AMPK/mTOR pathway activation. In conclusion, inhibition of testicular HMGB1/TLR4/NLRP3 pro-inflammatory axis and apoptosis alongside stimulation of autophagy were implicated in the favorable actions of linagliptin against cadmium-triggered testicular impairment.

Modulation of Reactive Oxygen Species Homeostasis as a Pleiotropic Effect of Commonly Used Drugs

Age-associated diseases represent a growing burden for global health systems in our aging society. Consequently, we urgently need innovative strategies to counteract these pathological disturbances. Overwhelming generation of reactive oxygen species (ROS) is associated with age-related damage, leading to cellular dysfunction and, ultimately, diseases. However, low-dose ROS act as crucial signaling molecules and inducers of a vaccination-like response to boost antioxidant defense mechanisms, known as mitohormesis. Consequently, modulation of ROS homeostasis by nutrition, exercise, or pharmacological interventions is critical in aging. Numerous nutrients and approved drugs exhibit pleiotropic effects on ROS homeostasis. In the current review, we provide an overview of drugs affecting ROS generation and ROS detoxification and evaluate the potential of these effects to counteract the development and progression of age-related diseases. In case of inflammation-related dysfunctions, cardiovascular- and neurodegenerative diseases, it might be essential to strengthen antioxidant defense mechanisms in advance by low ROS level rises to boost the individual ROS defense mechanisms. In contrast, induction of overwhelming ROS production might be helpful to fight pathogens and kill cancer cells. While we outline the potential of ROS manipulation to counteract age-related dysfunction and diseases, we also raise the question about the proper intervention time and dosage.

Vascular endotheliitis associated with infections: Its pathogenetic role and therapeutic implication

Vascular endothelial cells are major participants in and regulators of immune responses and inflammation. Vascular endotheliitis is regarded as a host immune-inflammatory response of the endothelium forming the inner surface of blood vessels in association with a direct consequence of infectious pathogen invasion. Vascular endotheliitis and consequent endothelial dysfunction can be a principle determinant of microvascular failure, which would favor impaired perfusion, tissue hypoxia, and subsequent organ failure. Emerging evidence suggests the role of vascular endotheliitis in the pathogenesis of coronavirus disease 2019 (COVID-19) and its related complications. Thus, once initiated, vascular endotheliitis and resultant cytokine storm cause systemic hyperinflammation and a thrombotic phenomenon in COVID-19, leading to acute respiratory distress syndrome and widespread organ damage. Vascular endotheliitis also appears to be a contributory factor to vasculopathy and coagulopathy in sepsis that is defined as life-threatening organ dysfunction due to a dysregulated response of the host to infection. Therefore, protecting endothelial cells and reversing vascular endotheliitis may be a leading therapeutic goal for these diseases associated with vascular endotheliitis. In this review, we outline the etiological and pathogenic importance of vascular endotheliitis in infection-related inflammatory diseases, including COVID-19, and possible mechanisms leading to vascular endotheliitis. We also discuss pharmacological agents which may be now considered as potential endotheliitis-based treatment modalities for those diseases.

Oral N-acetylcysteine as an adjunct to standard medical therapy improved heart function in cases with stable class II and III systolic heart failure

BACKGROUND

This research attempted to assess whether N-acetylcysteine (NAC) as adjunctive therapy can be useful in the treatment of patients with heart failure (HF).

METHODS

Fifty-five cases with diagnosed systolic HF and stable symptomatic New York Heart Association (NYHA) functional class II and III and on optimal medical treatment of HF for at least 3 months were assigned for receiving oral NAC (600 mg twice daily) or placebo for 12 weeks. The outcomes were changes in the echocardiographic hemodynamic indices as well as the patients' functional capacity assessed by NYHA classification over a 12-week treatment.

RESULTS

Compared to placebo, NAC more significantly improved the systolic left ventricular (LV) function expressed as the ejection fraction and Tei index. These changes are accompanied by more improvement in other LV echocardiographic indices including LV end-diastolic volume index and LV global longitudinal strain in the patients receiving NAC in comparison with those receiving placebo. In parallel with the improvement of LV function, right ventricular (RV) function expressed as RV fractional area change and RV Tei-index also got more improvement in those receiving NAC than those receiving placebo. However, the change in RV global longitudinal strain did not show a significant difference between study groups. Additionally, at week 12, the distribution of the NYHA functional class also shifted toward a better outcome in the NAC group in comparison with the placebo group; however, it was not significant.

CONCLUSIONS

These preliminary data support experimental findings showing that NAC supplementation is able to improve heart function.

TRIAL REGISTRATION

The registration of the trial was done at the Iranian Registry of Clinical Trials ( www.irct.ir ). Identifier code: IRCT20120215009014N333. Registration date: 2020-01-11.

Disturbed Lipid Metabolism in Diabetic Patients with Manifest Coronary Artery Disease Is Associated with Enhanced Inflammation

Background: Diabetic vasculopathy plays an important role in the pathophysiology of coronary artery disease (CAD) with oxidative stress as a strong mediator. This study aims to elucidate the underlying pathomechanisms of diabetic cardiac vasculopathy leading to coronary disease with an emphasis on the role of oxidative stress. Therefore, novel insights into antioxidant pathways might contribute to new strategies in the treatment and prevention of diabetic CAD. Methods: In 20 patients with insulin-dependent or non-insulin dependent diabetes mellitus (IDDM/NIDDM) and 39 non-diabetic (CTR) patients, myocardial markers of oxidative stress, vasoactive proteins, endothelial nitric oxide synthase (eNOS), activated phosphorylated eNOS (p-eNOS), and antioxidant enzymes, e.g., tetrahydrobiopterin generating dihydrofolate reductase (DHFR), heme oxygenase (HO-1), as well as serum markers of inflammation, e.g., E-selectin, interleukin-6 (IL-6), and lipid metabolism, e.g., high- and low-density lipoptrotein (HDL- and LDL-cholesterol) were determined in specimens of right atrial tissue and in blood samples from type 2 diabetic and non-diabetic patients undergoing coronary artery bypass graft (CABG) surgery. Results: IDDM/NIDDM increased markers of inflammation (e.g., E-selectin, p = 0.005 and IL-6, p = 0.051), decreased the phosphorylated myocardial p-eNOS (p = 0.032), upregulated the myocardial stress response protein HO-1 (p = 0.018), and enhanced the serum LDL-/HDL-cholesterol ratio (p = 0.019). However, the oxidative stress markers in the myocardium and the expression of vasoactive proteins (eNOS, DHFR) showed only marginal adverse changes in patients with IDDM/NIDDM. Conclusion: Dyslipidemia and myocardial inflammation seem to be the major determinants of diabetic CAD complications. Dysregulation in pro-oxidative enzymes might be attributable to the severity of CAD and oxidative stress levels in all included patients undergoing CABG.

Vascular and Cardiac Oxidative Stress and Inflammation as Targets for Cardioprotection

Cardiac and vascular diseases are often associated with increased oxidative stress and inflammation, and both may contribute to the disease progression. However, successful applications of antioxidants in the clinical setting are very rare and specific anti-inflammatory therapeutics only emerged recently. Reasons for this rely on the great diversity of oxidative stress and inflammatory cells that can either act as cardioprotective or cause tissue damage in the heart. Recent large-scale clinical trials found that highly specific anti-inflammatory therapies using monoclonal antibodies against cytokines resulted in lower cardiovascular mortality in patients with pre-existing atherosclerotic disease. In addition, unspecific antiinflammatory medication and established cardiovascular drugs with pleiotropic immunomodulatory properties such as angiotensin converting enzyme (ACE) inhibitors or statins have proven beneficial cardiovascular effects. Normalization of oxidative stress seems to be a common feature of these therapies, which can be explained by a close interaction/crosstalk of the cellular redox state and inflammatory processes. In this review, we give an overview of cardiac reactive oxygen species (ROS) sources and processes of cardiac inflammation as well as the connection of ROS and inflammation in ischemic cardiomyopathy in order to shed light on possible cardioprotective interventions.

Research Progress on Catalpol as Treatment for Atherosclerosis

Coronary atherosclerotic heart disease, cerebrovascular disease, and peripheral artery disease are common diseases with high morbidity and mortality rates and must be addressed. Their most frequent complications, including myocardial infarction and stroke, are caused by spontaneous thrombotic occlusion and are the most frequent cause of death worldwide. Atherosclerosis (AS) is the most widespread underlying pathological change for the above diseases. Therefore, drugs that interfere with this pathophysiological process must be incorporated in the treatment. Chinese traditional and herbal drugs can effectively treat AS. With the development of traditional Chinese medicine, the active ingredients in common Chinese medicinal materials must be thoroughly purified prior to their application in western medicine. Various proprietary Chinese medicine preparations with remarkable effects have been used in AS treatment. Catalpol, the active component of Rehmannia glutinosa, belongs to iridoid terpene and has anti-inflammatory, antioxidant, insulin resistance improvement, and other related effects. Several reviews have been conducted on this compound and its actions against osteoporosis, neurodegenerative diseases, Alzheimer's disease (AD), Parkinson's disease (PD) and diabetes and its complications. The current review focused on catalpol's effect on atherosclerotic plaque formation in different animal models. The potential mechanisms of catalpol to ameliorate AS were also summarized in terms of oxidative stress, inflammation, cell aging, apoptosis, and activation of the silent information regulator factor 2-related enzyme 1 (SIRT1) pathway.

Analysis of Global Oxidative Status Using Multimarker Scores Reveals a Specific Association Between Renal Dysfunction and Diuretic Therapy in Older Adults

Aging and chronic kidney disease (CKD) are important interrelated cardiovascular risk (CVR) factors linked to oxidative stress, but this relationship has not been well studied in older adults. We assessed the global oxidative status in an older population with normal to severely impaired renal function. We determined the oxidative status of 93 older adults (mean age 85 years) using multimarker scores. OxyScore was computed as index of systemic oxidative damage by analyzing carbonyl groups, oxidized low-density lipoprotein, 8-hydroxy-2'-deoxyguanosine, and xanthine oxidase activity. AntioxyScore was computed as index of antioxidant defense by analyzing catalase and superoxide dismutase (SOD) activity and total antioxidant capacity. OxyScore and AntioxyScore were higher in subjects with estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m2 than in peers with eGFR >60 mL/min/1.73 m2, with protein carbonyls, catalase, and SOD activity as major drivers. Older adults with a recent cardiovascular event had similar OxyScore and AntioxyScore as peers with eGFR >60 mL/min/1.73 m2. Multivariate linear regression analysis revealed that both indices were associated with decreased eGFR independently of traditional CVR factors. Interestingly, AntioxyScore was also associated with diuretic treatment, and a more pronounced increase was seen in subjects receiving combination therapy. The associations of AntioxyScore with diuretic treatment and eGFR were mutually independent. In conclusion, eGFR is the major contributor to the imbalance in oxidative stress in this older population. Given the association between oxidative stress, CKD, and CVR, the inclusion of renal function parameters in CVR estimators for older populations, such as the SCORE-OP, might improve their modest performance.

Redox-related biomarkers in human cardiovascular disease - classical footprints and beyond

Global epidemiological studies show that chronic non-communicable diseases such as atherosclerosis and metabolic disorders represent the leading cause of premature mortality and morbidity. Cardiovascular disease such as ischemic heart disease is a major contributor to the global burden of disease and the socioeconomic health costs. Clinical and epidemiological data show an association of typical oxidative stress markers such as lipid peroxidation products, 3-nitrotyrosine or oxidized DNA/RNA bases with all major cardiovascular diseases. This supports the concept that the formation of reactive oxygen and nitrogen species by various sources (NADPH oxidases, xanthine oxidase and mitochondrial respiratory chain) represents a hallmark of the leading cardiovascular comorbidities such as hyperlipidemia, hypertension and diabetes. These reactive oxygen and nitrogen species can lead to oxidative damage but also adverse redox signaling at the level of kinases, calcium handling, inflammation, epigenetic control, circadian clock and proteasomal system. The in vivo footprints of these adverse processes (redox biomarkers) are discussed in the present review with focus on their clinical relevance, whereas the details of their mechanisms of formation and technical aspects of their detection are only briefly mentioned. The major categories of redox biomarkers are summarized and explained on the basis of suitable examples. Also the potential prognostic value of redox biomarkers is critically discussed to understand what kind of information they can provide but also what they cannot achieve.

Discovery of new therapeutic redox targets for cardioprotection against ischemia/reperfusion injury and heart failure

Global epidemiological studies reported a shift from maternal/infectious communicable diseases to chronic non-communicable diseases and a major part is attributable to atherosclerosis and metabolic disorders. Accordingly, ischemic heart disease was identified as a leading risk factor for global mortality and morbidity with a prevalence of 128 million people. Almost 9 million premature deaths can be attributed to ischemic heart disease and subsequent acute myocardial infarction and heart failure, also representing a substantial socioeconomic burden. As evidenced by typical oxidative stress markers such as lipid peroxidation products or oxidized DNA/RNA bases, the formation of reactive oxygen species by various sources (NADPH oxidases, xanthine oxidase and mitochondrial resperatory chain) plays a central role for the severity of ischemia/reperfusion damage. The underlying mechanisms comprise direct oxidative damage but also adverse redox-regulation of kinase and calcium signaling, inflammation and cardiac remodeling among others. These processes and the role of reactive oxygen species are discussed in the present review. We also present and discuss potential targets for redox-based therapies that are either already established in the clinics (e.g. guanylyl cyclase activators and stimulators) or at least successfully tested in preclinical models of myocardial infarction and heart failure (mitochondria-targeted antioxidants). However, reactive oxygen species have not only detrimental effects but are also involved in essential cellular signaling and may even act protective as seen by ischemic pre- and post-conditioning or eustress - which makes redox therapy quite challenging.

Predicting the Potency of Anti-Alzheimer’s Drug Combinations Using Machine Learning

Clinical trials of single drugs intended to slow the progression of Alzheimer’s Disease (AD) have been notoriously unsuccessful. Combinations of repurposed drugs could provide effective treatments for AD. The challenge is to identify potentially effective combinations. To meet this challenge, machine learning (ML) was used to extract the knowledge from two leading AD databases, and then “the machine” predicted which combinations of the drugs in common between the two databases would be the most effective as treatments for AD. Specifically, three-layered artificial neural networks (ANNs) with compound, gated units in their internal layer were trained using ML to predict the cognitive scores of participants, separately in either database, given other data fields including age, demographic variables, comorbidities, and drugs taken. The predictions from the separately trained ANNs were statistically highly significantly correlated. The best drug combinations, jointly determined from both sets of predictions, were high in nonsteroidal anti-inflammatory drugs; anticoagulant, lipid-lowering, and antihypertensive drugs; and female hormones. The results suggest that the neurodegenerative processes that underlie AD and other dementias could be effectively treated using a combination of repurposed drugs. Predicted drug combinations could be evaluated in clinical trials.

Activation of autophagy by sitagliptin attenuates cadmium-induced testicular impairment in rats: Targeting AMPK/mTOR and Nrf2/HO-1 pathways

AIMS

Cadmium (Cd) is a prevalent environmental contaminant that incurs deleterious health effects, including testicular impairment. Sitagliptin, a selective dipeptidyl peptidase-4 (DPP-4) inhibitor, has demonstrated marked cardio-, hepato-, and reno-protective actions, however, its impact on Cd-triggered testicular dysfunction has not been formerly investigated. Hence, the present study aimed to explore the probable beneficial impact of sitagliptin against Cd-evoked testicular impairment which may add to its potential clinical utility. The underlying mechanisms pertaining to the balance between testicular autophagy and apoptosis were explored, including the AMPK/mTOR and Nrf2/HO-1 pathways.

MATERIALS AND METHODS

The testicular tissues were examined using histopathology, immunohistochemistry, Western blotting, and ELISA. Sitagliptin (10 mg/kg/day, by gavage) was administered for 4 consecutive weeks.

KEY FINDINGS

Sitagliptin attenuated the testicular impairment via improvement of the relative testicular weight, sperm count/motility, sperm abnormalities, and serum testosterone. Additionally, sitagliptin counteracted Cd-induced histologic aberrations/disrupted spermatogenesis. Interestingly, sitagliptin augmented the defective autophagy as demonstrated by upregulating Beclin 1 protein expression and lowering p62 SQSTM1 protein accumulation. These effects were mediated via the activation of testicular AMPK/mTOR pathway as proven by increasing p-AMPK (Ser485, Ser491)/total AMPK and diminishing p-mTOR (Ser2448)/total mTOR protein expression. Additionally, sitagliptin suppressed the testicular apoptotic events via downregulating Bax and upregulating Bcl-2 protein expression. In tandem, sitagliptin suppressed the oxidative stress through lowering lipid peroxides and activating Nrf2/HO-1 pathway via upregulating the protein expression of Nrf2, and the downstream effectors HO-1 and GPx.

SIGNIFICANCE

Sitagliptin attenuated Cd-induced testicular injury via boosting the autophagy/apoptosis ratio through activation of AMPK/mTOR and Nrf2/HO-1 pathways.

Ref-1 protects against FeCl3-induced thrombosis and tissue factor expression via the GSK3β-NF-κB pathway

Arterial thrombosis and its associated diseases are considered to constitute a major healthcare problem. Arterial thrombosis, defined as blood clot formation in an artery that interrupts blood circulation, is associated with many cardiovascular diseases. Oxidative stress is one of many important factors that aggravates the pathophysiological process of arterial thrombosis. Apurinic/apyrimidinic endonuclease 1/redox factor-1 (Ref-1) has a multifunctional role in cells that includes the regulation of oxidative stress and anti-inflammatory function. The aim of this study was to investigate the therapeutic effect of adenovirus-mediated Ref-1 overexpression on arterial thrombosis induced by 60% FeCl₃ solution in rats. Blood flow was measured to detect the time to occlusion, thrombus formation was detected by hematoxylin and eosin staining, reactive oxygen species (ROS) levels were detected by high-performance liquid chromatography, and the expression of tissue factor and other proteins was detected by Western blot. FeCl₃ aggravated thrombus formation in carotid arteries and reduced the time to artery occlusion. Ref-1 significantly delayed arterial obstruction via the inhibition of thrombus formation, especially by downregulating tissue factor expression through the Akt-GSK3β-NF-κB signaling pathway. Ref-1 also reduced the expression of vascular inflammation markers ICAM-1 and VCAM-1, and reduced the level of ROS that contributed to thrombus formation. The results showed that adenovirus-mediated Ref-1 overexpression reduced thrombus formation in the rat carotid artery. In summary, Ref-1 overexpression had anti-thrombotic effects in a carotid artery thrombosis model and could be a target for the treatment of arterial thrombosis.

Revisiting pharmacology of oxidative stress and endothelial dysfunction in cardiovascular disease: Evidence for redox-based therapies

According to the latest Global Burden of Disease Study data, non-communicable diseases in general and cardiovascular disease (CVD) in particular are the leading cause of premature death and reduced quality of life. Demographic shifts, unhealthy lifestyles and a higher burden of adverse environmental factors provide an explanation for these findings. The expected growing prevalence of CVD requires enhanced research efforts for identification and characterisation of novel therapeutic targets and strategies. Cardiovascular risk factors including classical (e.g. hypertension, diabetes, hypercholesterolaemia) and non-classical (e.g. environmental stress) factors induce the development of endothelial dysfunction, which is closely associated with oxidant stress and vascular inflammation and results in CVD, particularly in older adults. Most classically successful therapies for CVD display vasoprotective, antioxidant and anti-inflammatory effects, but were originally designed with other therapeutic aims. So far, only a few 'redox drugs' are in clinical use and many antioxidant strategies have not met expectations. With the present review, we summarise the actual knowledge on CVD pathomechanisms, with special emphasis on endothelial dysfunction, adverse redox signalling and oxidative stress, highlighting the preclinical and clinical evidence. In addition, we provide a brief overview of established CVD therapies and their relation to endothelial dysfunction and oxidative stress. Finally, we discuss novel strategies for redox-based CVD therapies trying to explain why, despite a clear link between endothelial dysfunction and adverse redox signalling and oxidative stress, redox- and oxidative stress-based therapies have not yet provided a breakthrough in the treatment of endothelial dysfunction and CVD.

Reductive Stress Causes Pathological Cardiac Remodeling and Diastolic Dysfunction

Aims: Redox homeostasis is tightly controlled and regulates key cellular signaling pathways. The cell's antioxidant response provides a natural defense against oxidative stress, but excessive antioxidant generation leads to reductive stress (RS). This study elucidated how chronic RS, caused by constitutive activation of nuclear erythroid related factor-2 (caNrf2)-dependent antioxidant system, drives pathological myocardial remodeling. Results: Upregulation of antioxidant transcripts and proteins in caNrf2-TG hearts (TGL and TGH; transgenic-low and -high) dose dependently increased glutathione (GSH) redox potential and resulted in RS, which over time caused pathological cardiac remodeling identified as hypertrophic cardiomyopathy (HCM) with abnormally increased ejection fraction and diastolic dysfunction in TGH mice at 6 months of age. While the TGH mice exhibited 60% mortality at 18 months of age, the rate of survival in TGL was comparable with nontransgenic (NTG) littermates. Moreover, TGH mice had severe cardiac remodeling at ∼6 months of age, while TGL mice did not develop comparable phenotypes until 15 months, suggesting that even moderate RS may lead to irreversible damages of the heart over time. Pharmacologically blocking GSH biosynthesis using BSO (l-buthionine-SR-sulfoximine) at an early age (∼1.5 months) prevented RS and rescued the TGH mice from pathological cardiac remodeling. Here we demonstrate that chronic RS causes pathological cardiomyopathy with diastolic dysfunction in mice due to sustained activation of antioxidant signaling. Innovation and Conclusion: Our findings demonstrate that chronic RS is intolerable and adequate to induce heart failure (HF). Antioxidant-based therapeutic approaches for human HF should consider a thorough evaluation of redox state before the treatment.

Regulation of Vascular Function and Inflammation via Cross Talk of Reactive Oxygen and Nitrogen Species from Mitochondria or NADPH Oxidase-Implications for Diabetes Progression

Oxidative stress plays a key role for the development of cardiovascular, metabolic, and neurodegenerative disease. This concept has been proven by using the approach of genetic deletion of reactive oxygen and nitrogen species (RONS) producing, pro-oxidant enzymes as well as by the overexpression of RONS detoxifying, antioxidant enzymes leading to an amelioration of the severity of diseases. Vice versa, the development and progression of cardiovascular diseases is aggravated by overexpression of RONS producing enzymes as well as deletion of RONS detoxifying enzymes. We have previously identified cross talk mechanisms between different sources of RONS, which can amplify the oxidative stress-mediated damage. Here, the pathways and potential mechanisms leading to this cross talk are analyzed in detail and highlighted by selected examples from the current literature and own data including hypoxia, angiotensin II (AT-II)-induced hypertension, nitrate tolerance, aging, and others. The general concept of redox-based activation of RONS sources via “kindling radicals” and enzyme-specific “redox switches” as well as the interaction with redox-sensitive inflammatory pathways are discussed. Here, we present evidence for the existence of such cross talk mechanisms in the setting of diabetes and critically assess their contribution to the severity of diabetic complications.

Oxidative stress and inflammation contribute to traffic noise-induced vascular and cerebral dysfunction via uncoupling of nitric oxide synthases

Environmental pollution and non-chemical stressors such as mental stress or traffic noise exposure are increasingly accepted as health risk factors with substantial contribution to chronic noncommunicable diseases (e.g. cardiovascular, metabolic and mental). Whereas the mechanisms of air pollution-mediated adverse health effects are well characterized, the mechanisms of traffic noise exposure are not completely understood, despite convincing clinical and epidemiological evidence for a significant contribution of environmental noise to overall mortality and disability. The initial mechanism of noise-induced cardiovascular, metabolic and mental disease is well defined by the „noise reaction model“ and consists of neuronal activation involving the hypothalamic-pituitary-adrenal (HPA) axis as well as the sympathetic nervous system, followed by a classical stress response via cortisol and catecholamines. Stress pathways are initiated by noise-induced annoyance and sleep deprivation/fragmentation. This review highlights the down-stream pathophysiology of noise-induced mental stress, which is based on an induction of inflammation and oxidative stress. We highlight the sources of reactive oxygen species (ROS) involved and the known targets for noise-induced oxidative damage. Part of the review emphasizes noise-triggered uncoupling/dysregulation of endothelial and neuronal nitric oxide synthase (eNOS and nNOS) and its central role for vascular dysfunction.

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Exposure to (traffic) noise causes non-auditory (indirect) cardiovascular and cerebral health harms via neuronal activation.

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Noise activates the HPA axis and sympathetic nervous system increasing levels of stress hormones, vasoconstrictors and ROS.

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Noise induces inflammation and stimulates several ROS sources leading to cerebral and cardiovascular oxidative damage.

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Noise leads to eNOS and nNOS uncoupling contributing to cardiometabolic disease and cognitive impairment.

Abnormal Ca2+ handling contributes to the impairment of aortic smooth muscle contractility in Zucker diabetic fatty rats

Vascular dysfunction is a common pathological basis for complications in individuals affected by diabetes. Previous studies have established that endothelial dysfunction is the primary contributor to vascular complications in type 2 diabetes (T2DM). However, the role of vascular smooth muscle cells (VSMCs) in vascular complications associated with T2DM is still not completely understood. The aim of this study is to explore the potential mechanisms associated with Ca²⁺ handling dysfunction and how this dysfunction contributes to diabetic vascular smooth muscle impairment. The results indicated that endothelium-dependent vasodilation was impaired in diabetic aortae, but endothelium-independent vasodilation was not altered. Various vasoconstrictors such as phenylephrine, U46619 and 5-HT could induce vasoconstriction in a concentration-dependent manner, such that the dose-response curve was parallel shifted to the right in diabetic aortae, compared to the control. Vasoconstrictions mediated by L-type calcium (Cav1.2) channels were attenuated in diabetic aortae, but effects mediated by store-operated calcium (SOC) channels were enhanced. Intracellular Ca²⁺ concentration ([Ca²⁺]_i) in VSMCs was detected by Fluo-4 calcium fluorescent probes, and demonstrated that SOC-mediated Ca²⁺ entry was increased in diabetic VSMCs. VSMC-specific knockout of STIM1 genes decreased SOC-mediated and phenylephrine-induced vasoconstrictive response in mice aortae. Additionally, Orai1 expression was up-regulated, Cav1.2 expression was downregulated, and the phenotypic transformation of diabetic VSMCs was determined in diabetic aortae. The overexpression of Orai1 markedly promoted the OPN expression of VSMCs, whereas SKF96365 (SOC channel blocker) reversed the phenotypic transformation of diabetic VSMCs. Our results demonstrated that the vasoconstriction response of aortic smooth muscle was weakened in type 2 diabetic rats, which was related to the downregulation of the Cav1.2 channel and the up-regulation of the SOC channel signaling pathway.

Lifetime cardiovascular risk is associated with a multimarker score of systemic oxidative status in young adults independently of traditional risk factors

Cardiovascular risk (CVR) tends to be estimated in the short-term, which underestimates lifetime (LT)-CVR of young subjects. We determined whether LT-CVR is associated with a multimarker score of oxidative status in young adults and whether this association is independent of traditional CVR factors. Seventy-two young adults were stratified into: (1) low or (2) high LT-CVR, and (3) stable coronary artery disease (SCAD). CVR was estimated with QRisk and atherosclerotic CV disease (ASCVD) risk estimators, or second manifestations of arterial disease (SMART). Risk score. oxidative damage was determined by measuring carbonyls, oxidized LDL (oxLDL), 8-hydroxy-2'-deoxyguanosine (8-OHdG), and xanthine oxidase activity. Antioxidant defence was determined by total antioxidant capacity (TAC), catalase (CAT) activity and superoxide dismutase (SOD) activity. Multimarker scores of systemic oxidative damage (OxyScore) and antioxidant defence (AntioxyScore) were computed as standardized variables. Subjects with high LT-CVR had significantly higher levels of oxLDL, 8-OHdG, TAC, and CAT activity than subjects with low LT-CVR or with SCAD. QRisk and ASCVD estimators correlated positively with oxLDL, TAC, and CAT activity, while SMART Risk Score correlated with carbonyls and SOD activity. OxyScore and AntioxyScore were significantly higher in subjects with high LT-CVR than with low LT-CVR or with SCAD. OxyScore, but not AntioxyScore, was associated with LT-CVR independently of each traditional CVR factor. This study for the first time demonstrates a positive association between oxidative stress and the risk of first and recurrent CV events in young adults.

Effects of quercetin, sitagliptin alone or in combination in testicular toxicity induced by doxorubicin in rats

Objective

This study aimed to evaluate the effect of quercetin and/or sitagliptin on testicular damage induced by doxorubicin (DOX).

Methodology

Twenty-five male Wistar rats, weighing 240±20 g, were randomly divided into five groups as follows: a negative control group; that was treated with 1 mL of 0.9% sodium chloride; a DOX-treated group received Intraperitoneal (I.P.) DOX injection (3 mg/kg); a group treated with quercetin 80 mg/kg + sitagliptin 10 mg/kg + DOX; a group treated with quercetin 80 mg/kg + DOX; and a group treated with sitagliptin 10 mg/kg+ DOX. All treatment were given orally daily for 21 days with I.P. DOX 3 mg/kg injection for the treatment groups at days 8, 10, 12, 15, 17, and 19. On day 22, blood was collected for analysis of testosterone, luteinizing hormone (LH), follicle-stimulating hormone (FSH), alkaline phosphatase (ALP), lactate dehydrogenase (LDH), glutathione peroxidase (GPx), and total antioxidant capacity (TAOC). The testes were also removed and sent for histopathological examination.

Results

The study revealed that the combination of quercetin with sitagliptin produced a significant increase in testosterone and FSH levels with a non-significant increase in LH level. This combination also non-significantly decreased the level of ALP and LDH and restored the GPx level with enhancing TAOC.

Conclusion

The results suggest quercetin/sitagliptin combination as a promising therapeutic modality for attenuation of DOX-induced testicular toxicity in rats, and the main mechanism involved in such effect could be due to the antioxidant and anti-inflammatory properties of both agents.

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Changes in microparticle profiles by vitamin D receptor activation in chronic kidney disease - a randomized trial

Background

Microparticles (MPs) are biomarkers and mediators of disease through their expression of surface receptors, reflecting activation or stress in their parent cells. Endothelial markers, ICAM-1 and VCAM-1, are implicated in atherosclerosis and associated with cardiovascular risk. Chronic kidney disease (CKD) patients have endothelial dysfunction and high levels of endothelial derived MPs. Vitamin D treatment has been reported to ameliorate endothelial function in CKD patients. We aimed to examine cell specific MP profiles and concentrations of MPs expressing the atherosclerotic markers ICAM-1 and VCAM-1 after treatment with paricalcitol in patients with CKD stage 3–4.

Methods

Sub-study of the previously reported SOLID trial where 36 patients were randomly assigned to placebo, 1 or 2 μg paricalcitol, for 12 weeks. MPs were measured by flow cytometry after labelling with antibodies against endothelial (CD62E), platelet (CD62P, CD41, CD154) leukocyte (CD45) and vascular (CD54, CD106) markers.

Results

Patients had a mean age of 65 years with a mean eGFR of 40 mL/min/1.73m². Concentrations of ICAM-1 positive MPs were significantly reduced by treatment (repeated measures ANOVA p = 0.04). Repeated measures MANOVA of concentrations of endothelial, platelet and leukocyte MPs showed sustained levels in the 2 μg treatment group (p = 0.85) but a decline in the 1 μg (p = 0.04) and placebo groups (p = 0.005).

Conclusions

Treatment with paricalcitol reduces concentrations of ICAM-1 positive MPs. This is accompanied by sustained concentrations of all cell specific MPs in the 2 μg group, and decreasing concentrations in the other groups, possibly due to a more healthy and reactive endothelium with paricalcitol treatment.

Vascular Inflammation and Oxidative Stress: Major Triggers for Cardiovascular Disease

Cardiovascular disease is a leading cause of death and reduced quality of life, proven by the latest data of the Global Burden of Disease Study, and is only gaining in prevalence worldwide. Clinical trials have identified chronic inflammatory disorders as cardiovascular risks, and recent research has revealed a contribution by various inflammatory cells to vascular oxidative stress. Atherosclerosis and cardiovascular disease are closely associated with inflammation, probably due to the close interaction of inflammation with oxidative stress. Classical therapies for inflammatory disorders have demonstrated protective effects in various models of cardiovascular disease; especially established drugs with pleiotropic immunomodulatory properties have proven beneficial cardiovascular effects; normalization of oxidative stress seems to be a common feature of these therapies. The close link between inflammation and redox balance was also supported by reports on aggravated inflammatory phenotype in the absence of antioxidant defense proteins (e.g., superoxide dismutases, heme oxygenase-1, and glutathione peroxidases) or overexpression of reactive oxygen species producing enzymes (e.g., NADPH oxidases). The value of immunomodulation for the treatment of cardiovascular disease was recently supported by large-scale clinical trials demonstrating reduced cardiovascular mortality in patients with established atherosclerotic disease when treated by highly specific anti-inflammatory therapies (e.g., using monoclonal antibodies against cytokines). Modern antidiabetic cardiovascular drugs (e.g., SGLT2 inhibitors, DPP-4 inhibitors, and GLP-1 analogs) seem to share these immunomodulatory properties and display potent antioxidant effects, all of which may explain their successful lowering of cardiovascular risk.

CD40L controls obesity-associated vascular inflammation, oxidative stress, and endothelial dysfunction in high fat diet-treated and db/db mice

Aims

CD40 ligand (CD40L) signaling controls vascular oxidative stress and related dysfunction in angiotensin-II-induced arterial hypertension by regulating vascular immune cell recruitment and platelet activation. Here we investigated the role of CD40L in experimental hyperlipidemia.

Methods and results

Male wild type and CD40L-/- mice (C57BL/6 background) were subjected to high fat diet for sixteen weeks. Weight, cholesterol, HDL, and LDL levels, endothelial function (isometric tension recording), oxidative stress (NADPH oxidase expression, dihydroethidium fluorescence) and inflammatory parameters (inducible nitric oxide synthase, interleukin-6 expression) were assessed. CD40L expression, weight, leptin and lipids were increased, and endothelial dysfunction, oxidative stress and inflammation were more pronounced in wild type mice on a high fat diet, all of which was almost normalized by CD40L deficiency. Similar results were obtained in diabetic db/db mice with CD40/TRAF6 inhibitor (6877002) therapy. In a small human study higher serum sCD40L levels and an inflammatory phenotype were detected in the blood and Aorta ascendens of obese patients (body mass index > 35) that underwent by-pass surgery.

Conclusion

CD40L controls obesity-associated vascular inflammation, oxidative stress and endothelial dysfunction in mice and potentially humans. Thus, CD40L represents a therapeutic target in lipid metabolic disorders which is a leading cause in cardiovascular disease.

New Therapeutic Implications of Endothelial Nitric Oxide Synthase (eNOS) Function/Dysfunction in Cardiovascular Disease

The Global Burden of Disease Study identified cardiovascular risk factors as leading causes of global deaths and life years lost. Endothelial dysfunction represents a pathomechanism that is associated with most of these risk factors and stressors, and represents an early (subclinical) marker/predictor of atherosclerosis. Oxidative stress is a trigger of endothelial dysfunction and it is a hall-mark of cardiovascular diseases and of the risk factors/stressors that are responsible for their initiation. Endothelial function is largely based on endothelial nitric oxide synthase (eNOS) function and activity. Likewise, oxidative stress can lead to the loss of eNOS activity or even “uncoupling” of the enzyme by adverse regulation of well-defined “redox switches” in eNOS itself or up-/down-stream signaling molecules. Of note, not only eNOS function and activity in the endothelium are essential for vascular integrity and homeostasis, but also eNOS in perivascular adipose tissue plays an important role for these processes. Accordingly, eNOS protein represents an attractive therapeutic target that, so far, was not pharmacologically exploited. With our present work, we want to provide an overview on recent advances and future therapeutic strategies that could be used to target eNOS activity and function in cardiovascular (and other) diseases, including life style changes and epigenetic modulations. We highlight the redox-regulatory mechanisms in eNOS function and up- and down-stream signaling pathways (e.g., tetrahydrobiopterin metabolism and soluble guanylyl cyclase/cGMP pathway) and their potential pharmacological exploitation.

Benefits of multiple micronutrient supplementation in heart failure: A comprehensive review

BACKGROUND

Multiple micronutrient supplementation has been suggested to have a role on health outcomes in patients with heart failure (HF), but the evidence is inconclusive.

OBJECTIVE

To elucidate the role of multiple micronutrient supplementation in heart failure we performed a comprehensive review of the literature.

METHODS AND RESULTS

The search in databases included PUBMED (until June 2018) to detect randomized controlled trials (RCTs) and meta-analyzes that investigated the impact of micronutrient supplementation in HF.

RESULTS

With more than 2357 titles and abstracts reviewed, we included only the studies suitable for the final review. Whether alone or in combination, micronutrients have been found to improve the health outcomes of patients with HF by improving symptoms, work capacity and left ventricular ejection fraction (LVEF), thus increasing the quality of life in these patients.

CONCLUSION

Future studies are needed to document the effects of multiple micronutrient associations in order to include them in nutritional guidelines to increase survival and to improve quality of life in patients with heart failure.

Advances in the relationship between Kruppel-like factor 15 and cardiovascular disease research

Kruppel-like factor 15 (KLF15) is a subtype of the Kruppel-like family of transcription factors (KLFs). KLFs have three high-fidelity zinc fingers at the carboxyl terminus that enable them to regulate the biological processes of proliferation, differentiation, cellular development, and apoptosis. KLF15 is highly expressed in the kidney, pancreas, and cardiac and skeletal muscle, and plays an essential role in the development and occurrence of multiple system diseases. In this paper, we underscored the important relationship between KLF15 and cardiovascular diseases such as atherosclerosis, heart failure, arrhythmia, aortic lesions, etc. On this basis, we identified KLF15 as a potential therapeutic target for the treatment of cardiovascular disease.

Cafestol Inhibits Cyclic-Strain-Induced Interleukin-8, Intercellular Adhesion Molecule-1, and Monocyte Chemoattractant Protein-1 Production in Vascular Endothelial Cells

Moderate coffee consumption is inversely associated with cardiovascular disease mortality; however, mechanisms underlying this causal effect remain unclear. Cafestol, a diterpene found in coffee, has various properties, including an anti-inflammatory property. This study investigated the effect of cafestol on cyclic-strain-induced inflammatory molecule secretion in vascular endothelial cells. Cells were cultured under static or cyclic strain conditions, and the secretion of inflammatory molecules was determined using enzyme-linked immunosorbent assay. The effects of cafestol on mitogen-activated protein kinases (MAPK), heme oxygenase-1 (HO-1), and sirtuin 1 (Sirt1) signaling pathways were examined using Western blotting and specific inhibitors. Cafestol attenuated cyclic-strain-stimulated intercellular adhesion molecule-1 (ICAM-1), monocyte chemoattractant protein- (MCP-) 1, and interleukin- (IL-) 8 secretion. Cafestol inhibited the cyclic-strain-induced phosphorylation of extracellular signal-regulated kinase and p38 MAPK. By contrast, cafestol upregulated cyclic-strain-induced HO-1 and Sirt1 expression. The addition of zinc protoporphyrin IX, sirtinol, or Sirt1 silencing (transfected with Sirt1 siRNA) significantly attenuated cafestol-mediated modulatory effects on cyclic-strain-stimulated ICAM-1, MCP-1, and IL-8 secretion. This is the first study to report that cafestol inhibited cyclic-strain-induced inflammatory molecule secretion, possibly through the activation of HO-1 and Sirt1 in endothelial cells. The results provide valuable insights into molecular pathways that may contribute to the effects of cafestol.

Protective effects of melatonin and glucagon-like peptide-1 receptor agonist (liraglutide) on gastric ischaemia-reperfusion injury in high-fat/sucrose-fed rats

Ischaemia-reperfusion (I-R) injury is a serious pathology that is often encountered with thrombotic events, during surgery when blood vessels are cross-clamped, and in organs for transplantation. Increased oxidative stress is the main pathology in I-R injury, as assessed in studies on the heart, kidney, and brain with little data available on gastric I-R (GI-R). Liraglutide is a GLP-1 receptor agonist that has insulinotropic and weight reducing actions, and melatonin that has been much studied as a chronotropic hormone; have also studied as being anti-oxidative stress agents. Herein, we aimed to explore the effects of liraglutide and melatonin on GI-R injury with high-fat/sucrose diet. Rats were divided into six groups; two diet-control, two melatonin- and two liraglutide-pretreated groups. All rats were subjected to 30 minutes of gastric ischaemia followed by 1 hour of reperfusion. Gastric tissues were assessed for the percentage of DNA fragmentation, myeloperoxidase activity, total oxidant status, total antioxidant capacity, oxidative stress index, BMI and histopathological examination. We showed that high-fat feeding for four weeks prior to GI-R significantly increased BMI, oxidative stress indices and decreased total antioxidant capacity, with a neutral effect on apoptosis compared to controls. Pretreatment with either melatonin (10 mg/kg per day orally) or liraglutide (25 μg/kg per day ip) reverses these effects. Furthermore, both drugs reduced weight only in HFS-fed rats. Both liraglutide and melatonin have nearly similar protective effects on gastric I-R injury through decreasing the oxidative stress and apoptosis.

Scutellarin protects against vascular endothelial dysfunction and prevents atherosclerosis via antioxidation

BACKGROUND

Scutellarin is the major constituent responsible for the clinical benefits of Erigeron breviscapus (Vant.) Hand.-Mazz which finds a long history of ethnopharmacological use in Traditional Chinese Medicine. Scutellarin as a pure compound is now under investigation for its protections against various tissue injuries.

PURPOSE

This study aims to examine the effects of scutellarin on oxidative stress-induced vascular endothelial dysfunction and endothelial cell damage, and then to evaluate the therapeutic efficacy of scutellarin in preventing atherosclerosis in rats.

METHODS

Radical scavenging ability of scutellarin was determined in vitro. Impact of scutellarin on endothelium-dependent relaxation (EDR) of rabbit thoracic aortic rings upon 1, 1-diphenyl-2-picrylhydrazyl (DPPH) challenge was measured. Influences of scutellarin pre-treatment on the levels of reactive oxygen species (ROS), activities of antioxidant enzymes superoxide dismutase (SOD), glutathione peroxidase and catalase, and the expression of SOD1 and NADPH oxidase 4 (Nox4) in human umbilical vein endothelial cells (HUVECs) injured by H₂O₂ were examined. Anti-atherosclerotic effect of scutellarin was evaluated in rats fed with high fat diet (HFD).

RESULTS

Scutellarin showed potent antioxidant activity in vitro. Pretreatment of scutellarin retained the EDR of rabbit thoracic aortic rings damaged by DPPH. In H₂O₂ injured-HUVECs the deleterious alterations in ROS levels and antioxidant enzymes activity were reversed by scutellarin and the mRNA and protein expression of SOD1 and Nox4 were restored also. Oral administration of scutellarin dose-dependently ameliorated hyperlipidemia in HFD-fed rats and alleviated oxidative stress in rat serum, mimicking the effects of reference drug atorvastatin.

CONCLUSION

Scutellarin protects against oxidative stress-induced vascular endothelial dysfunction and endothelial cell damage in vitro and prevents atherosclerosis in vivo through antioxidation. The results rationalize further investigation into the clinical use of scutellarin in cardiovascular diseases.

Purification and activity characterization of polysaccharides in the medicinal lichen Umbilicaria tornata from Taibai Mountain, China

Water-soluble polysaccharides from Umbilicaria tornata (UTP) were purified and preliminarily characterized. The antioxidant and antitumor activities of crude UTP and two purified fractions (UTP-1 and UTP-2) were evaluated using in vitro experiments. The results showed that the molecular weights of UTP-1 and UTP-2 were 84.86 and 28.66 kDa, respectively. Both UTP-1 and UTP-2 were composed of glucose and xylose, with their molar ratios being 1.3:0.9 and 0.9:4.6, respectively. In addition, crude UTP, UTP-1 and UTP-2 showed dose-dependent DPPH and hydroxyl radical scavenging and reducing activities. However, crude UTP exhibited stronger antioxidant activity than UTP-1 and UTP-2, particularly in terms of DPPH radicals. Crude UTP and the two purified fractions inhibited the growth of HeLa, HepG2, A375, MCF-7, SGC7901 and Caco2 cancer cells in vitro. Compared with UTP-1 and UTP-2, crude UTP presented significantly higher antitumor activity in vitro against HeLa and HepG2 cells (p < 0.05). These findings provide a scientific basis for the deeper exploration and resource development of U. tornata.

Time Response of Oxidative/Nitrosative Stress and Inflammation in LPS-Induced Endotoxaemia-A Comparative Study of Mice and Rats

Sepsis is a severe and multifactorial disease with a high mortality rate. It represents a strong inflammatory response to an infection and is associated with vascular inflammation and oxidative/nitrosative stress. Here, we studied the underlying time responses in the widely used lipopolysaccharide (LPS)-induced endotoxaemia model in mice and rats. LPS (10 mg/kg; from Salmonella Typhosa) was intraperitoneally injected into mice and rats. Animals of every species were divided into five groups and sacrificed at specific points in time (0, 3, 6, 9, 12 h). White blood cells (WBC) decreased significantly in both species after 3 h and partially recovered with time, whereas platelet decrease did not recover. Oxidative burst and iNOS-derived nitrosyl-iron hemoglobin (HbNO) increased with time (maxima at 9 or 12 h). Immune cell infiltration (CD68 and F4/80 content) showed an increase with time, which was supported by increased vascular mRNA expression of VCAM-1, P-selectin, IL-6 and TNF-α. We characterized the time responses of vascular inflammation and oxidative/nitrosative stress in LPS-induced endotoxaemic mice and rats. The results of this study will help to interpret and compare data from different animal species in LPS-induced endotoxaemia models for the identification of new drug targets.

European contribution to the study of ROS: A summary of the findings and prospects for the future from the COST action BM1203 (EU-ROS)

The European Cooperation in Science and Technology (COST) provides an ideal framework to establish multi-disciplinary research networks. COST Action BM1203 (EU-ROS) represents a consortium of researchers from different disciplines who are dedicated to providing new insights and tools for better understanding redox biology and medicine and, in the long run, to finding new therapeutic strategies to target dysregulated redox processes in various diseases. This report highlights the major achievements of EU-ROS as well as research updates and new perspectives arising from its members. The EU-ROS consortium comprised more than 140 active members who worked together for four years on the topics briefly described below. The formation of reactive oxygen and nitrogen species (RONS) is an established hallmark of our aerobic environment and metabolism but RONS also act as messengers via redox regulation of essential cellular processes. The fact that many diseases have been found to be associated with oxidative stress established the theory of oxidative stress as a trigger of diseases that can be corrected by antioxidant therapy. However, while experimental studies support this thesis, clinical studies still generate controversial results, due to complex pathophysiology of oxidative stress in humans. For future improvement of antioxidant therapy and better understanding of redox-associated disease progression detailed knowledge on the sources and targets of RONS formation and discrimination of their detrimental or beneficial roles is required. In order to advance this important area of biology and medicine, highly synergistic approaches combining a variety of diverse and contrasting disciplines are needed.

Peripheral artery disease, redox signaling, oxidative stress - Basic and clinical aspects

Reactive oxygen and nitrogen species (ROS and RNS, e.g. H2O2, nitric oxide) confer redox regulation of essential cellular signaling pathways such as cell differentiation, proliferation, migration and apoptosis. At higher concentrations, ROS and RNS lead to oxidative stress and oxidative damage of biomolecules (e.g. via formation of peroxynitrite, fenton chemistry). Peripheral artery disease (PAD) is characterized by severe ischemic conditions in the periphery leading to intermittent claudication and critical limb ischemia (end stage). It is well known that redox biology and oxidative stress play an important role in this setting. We here discuss the major pathways of oxidative stress and redox signaling underlying the disease progression with special emphasis on the contribution of inflammatory processes. We also highlight therapeutic strategies comprising pharmacological (e.g. statins, angiotensin-converting enzyme inhibitors, phosphodiesterase inhibition) and non-pharmacological (e.g. exercise) interventions. Both of these strategies induce potent indirect antioxidant and anti-inflammatory mechanisms that may contribute to an improvement of PAD associated complications and disease progression by removing excess formation of ROS and RNS (e.g. by ameliorating primary complications such as hyperlipidemia and hypertension) as well as the normalization of the inflammatory phenotype suppressing the progression of atherosclerosis.

Redox regulation of cardiovascular inflammation - Immunomodulatory function of mitochondrial and Nox-derived reactive oxygen and nitrogen species

Oxidative stress is a major hallmark of cardiovascular diseases although a causal link was so far not proven by large clinical trials. However, there is a close association between oxidative stress and inflammation and increasing evidence for a causal role of (low-grade) inflammation for the onset and progression of cardiovascular diseases, which may serve as the missing link between oxidative stress and cardiovascular morbidity and mortality. With the present review we would like to highlight the multiple redox regulated pathways in inflammation, discuss the sources of reactive oxygen and nitrogen species that are of interest for these processes and finally discuss the importance of angiotensin II (AT-II) as a trigger of cardiovascular inflammation and the initiation and progression of cardiovascular diseases.

Integrated evaluation of HPLC and UV fingerprints for the quality control of Danshen tablet by systematic quantified fingerprint method combined with antioxidant activity

Danshen tablet, which consists of Salviae Miltiorrhizae Radix et Rhizoma, Notoginseng Radix et Rhizoma and Borneolum syntheticum, has been widely used in the therapy of cardiovascular disease. The aim of this study was to develop comprehensive evaluation methods for the quality control of Danshen tablet. First, five-wavelength fusion fingerprint was established to avoid one-sidedness of a single wavelength. Then, the ultraviolet spectrum fingerprint was applied to reflect the information of unsaturated bond and conjugated system of chemical substances in Danshen tablet. The similarity analyses of these two fingerprints were performed by systematic quantified fingerprint method in terms of qualitative and quantitative aspects. After that, the evaluation results of high-performance liquid chromatography and ultraviolet fingerprints were integrated by the mean algorithm, which could reduce the error caused by single method. The integrated evaluation results showed that 30 batches of samples were classified into seven grades. Finally, the fingerprint-efficacy relationship was established using an on-line antioxidant system and partial least-squares model to explore the connection between chemical components and antioxidant activities. The methods established in this paper were found suitable for the analysis of Danshen tablet.

Hypaphorine Attenuates Lipopolysaccharide-Induced Endothelial Inflammation via Regulation of TLR4 and PPAR-γ Dependent on PI3K/Akt/mTOR Signal Pathway

Endothelial lesion response to injurious stimuli is a necessary step for initiating inflammatory cascades in blood vessels. Hypaphorine (Hy) from different marine sources is shown to exhibit anti-inflammatory properties. However, the potential roles and possible molecular mechanisms of Hy in endothelial inflammation have yet to be fully clarified. We showed that Hy significantly inhibited the positive effects of lipopolysaccharide (LPS) on pro-inflammatory cytokines expressions, including tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), monocyte chemoattractant protein 1 (MCP-1) and vascular cellular adhesion molecule-1 (VCAM-1), as well as induction of the phosphorylation of Akt and mTOR in HMEC-1 cells. The downregulated peroxisome proliferator-activated receptor γ (PPAR-γ) and upregulated toll-like receptor 4 (TLR4) expressions in LPS-challenged endothelial cells were prevented by Hy. Inhibition of both PI3K and mTOR reversed LPS-stimulated increases in TLR4 expressions and decreases in PPAR-γ levels. Genetic silencing of TLR4 or PPAR-γ agonist pioglitazone obviously abrogated the levels of pro-inflammatory cytokines in LPS-treated HMEC-1 cells. These results suggest that Hy may exert anti-inflammatory actions through the regulation of TLR4 and PPAR-γ dependent on PI3K/Akt/mTOR signal pathways. Hy may be considered as a therapeutic agent that can potentially relieve or ameliorate endothelial inflammation-associated diseases.

Functional and Biochemical Endothelial Profiling In Vivo in a Murine Model of Endothelial Dysfunction; Comparison of Effects of 1-Methylnicotinamide and Angiotensin-converting Enzyme Inhibitor

Although it is known that 1-methylnicotinamide (MNA) displays vasoprotective activity in mice, as yet the effect of MNA on endothelial function has not been demonstrated in vivo. Here, using magnetic resonance imaging (MRI) we profile the effects of MNA on endothelial phenotype in mice with atherosclerosis (ApoE/LDLR^-/-) in vivo, in comparison to angiotensin (Ang) -converting enzyme (ACE) inhibitor (perindopril), with known vasoprotective activity. On a biochemical level, we analyzed whether MNA- or perindopril-induced improvement in endothelial function results in changes in ACE/Ang II-ACE2/Ang-(1–7) balance, and L-arginine/asymmetric dimethylarginine (ADMA) ratio. Endothelial function and permeability were evaluated in the brachiocephalic artery (BCA) in 4-month-old ApoE/LDLR^-/- mice that were non-treated or treated for 1 month or 2 months with either MNA (100 mg/kg/day) or perindopril (10 mg/kg/day). The 3D IntraGate^®FLASH sequence was used for evaluation of BCA volume changes following acetylcholine (Ach) administration, and for relaxation time (T₁) mapping around BCA to assess endothelial permeability using an intravascular contrast agent. Activity of ACE/Ang II and ACE2/Ang-(1–7) pathways as well as metabolites of L-arginine/ADMA pathway were measured using liquid chromatography/mass spectrometry-based methods. In non-treated 6-month-old ApoE/LDLR^-/- mice, Ach induced a vasoconstriction in BCA that amounted to –7.2%. 2-month treatment with either MNA or perindopril resulted in the reversal of impaired Ach-induced response to vasodilatation (4.5 and 5.5%, respectively) and a decrease in endothelial permeability (by about 60% for MNA-, as well as perindopril-treated mice). Improvement of endothelial function by MNA and perindopril was in both cases associated with the activation of ACE2/Ang-(1–7) and the inhibition of ACE/Ang II axes as evidenced by an approximately twofold increase in Ang-(1–9) and Ang-(1–7) and a proportional decrease in Ang II and its active metabolites. Finally, MNA and perindopril treatment resulted in an increase in L-arginine/ADMA ratio by 107% (MNA) and 140% (perindopril), as compared to non-treated mice. Functional and biochemical endothelial profiling in ApoE/LDLR^-/- mice in vivo revealed that 2-month treatment with MNA (100 mg/kg/day) displayed a similar profile of vasoprotective effect as 2-month treatment with perindopril (10 mg/kg/day): i.e., the improvement in endothelial function that was associated with the beneficial changes in ACE/Ang II-ACE2/Ang (1–7) balance and in L-arginine/ADMA ratio in plasma.

Effect of a plant sterol-enriched spread on biomarkers of endothelial dysfunction and low-grade inflammation in hypercholesterolaemic subjects

Plant sterols (PS) lower LDL-cholesterol, an established risk factor for CHD. Endothelial dysfunction and low-grade inflammation are two important features in the development of atherosclerosis. Whether PS affect biomarkers of endothelial function and low-grade inflammation is not well studied. The aim of the present study was to investigate the effect of regular intake of PS on biomarkers of endothelial dysfunction and low-grade inflammation. In a double-blind, randomised, placebo-controlled, parallel-group study, which was primarily designed to investigate the effect of PS intake on vascular function (clinicaltrials.gov: NCT01803178), 240 hypercholesterolaemic but otherwise healthy men and women consumed a low-fat spread with added PS (3 g/d) or a placebo spread for 12 weeks. Endothelial dysfunction biomarkers (both vascular and intracellular adhesion molecules 1 and soluble endothelial-selectin) and low-grade inflammation biomarkers (C-reactive protein, serum amyloid A, IL-6, IL-8, TNF-α and soluble intercellular adhesion molecule-1) were measured using a multi-array detection system based on electrochemiluminescence technology. Biomarkers were combined using z-scores. Differences in changes from baseline between the PS and the placebo groups were assessed. The intake of PS did not significantly change the individual biomarkers of endothelial dysfunction and low-grade inflammation. The z-scores for endothelial dysfunction (−0·02; 95 % CI −0·15, 0·11) and low-grade inflammation (−0·04; 95 % CI −0·16, 0·07) were also not significantly changed after PS intake compared with placebo. In conclusion, biomarkers of endothelial dysfunction and low-grade inflammation were not affected by regular intake of 3 g/d PS for 12 weeks in hypercholesterolaemic men and women.

Glucagon-like peptide-1 receptor signalling reduces microvascular thrombosis, nitro-oxidative stress and platelet activation in endotoxaemic mice

BACKGROUND AND PURPOSE

Excessive inflammation in sepsis causes microvascular thrombosis and thrombocytopenia associated with organ dysfunction and high mortality. The present studies aimed to investigate whether inhibition of dipeptidyl peptidase-4 (DPP-4) and supplementation with glucagon-like peptide-1 (GLP-1) receptor agonists improved endotoxaemia-associated microvascular thrombosis via immunomodulatory effects.

EXPERIMENTAL APPROACH

Endotoxaemia was induced in C57BL/6J mice by a single injection of LPS (17.5 mg kg^-1 for survival and 10 mg kg^-1 for all other studies). For survival studies, treatment was started 6 h after LPS injection. For all other studies, drugs were injected 48 h before LPS treatment.

KEY RESULTS

Mice treated with LPS alone showed severe thrombocytopenia, microvascular thrombosis in the pulmonary circulation (fluorescence imaging), increased LDH activity, endothelial dysfunction and increased markers of inflammation in aorta and whole blood (leukocyte-dependent oxidative burst, nitrosyl-iron haemoglobin, a marker of nitrosative stress, and expression of inducible NOS). Treatment with the DPP-4 inhibitor linagliptin or the GLP-1 receptor agonist liraglutide, as well as genetic deletion of DPP-4 (DPP4^-/- mice) improved all these parameters. In GLP-1 receptor-deficient mice, both linagliptin and liraglutide lost their beneficial effects and improvement of prognosis. Incubation of platelets and cultured monocytes (containing GLP-1 receptor protein) with GLP-1 receptor agonists inhibited the monocytic oxidative burst and platelet activation, with a GLP-1 receptor-dependent elevation of cAMP levels and PKA activation.

CONCLUSIONS AND IMPLICATIONS

GLP-1 receptor activation in platelets by linagliptin and liraglutide strongly attenuated endotoxaemia-induced microvascular thrombosis and mortality by a cAMP/PKA-dependent mechanism, preventing systemic inflammation, vascular dysfunction and end organ damage.

LINKED ARTICLES

This article is part of a themed section on Redox Biology and Oxidative Stress in Health and Disease. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.12/issuetoc.

Targeting vascular (endothelial) dysfunction

Cardiovascular diseases are major contributors to global deaths and disability-adjusted life years, with hypertension a significant risk factor for all causes of death. The endothelium that lines the inner wall of the vasculature regulates essential haemostatic functions, such as vascular tone, circulation of blood cells, inflammation and platelet activity. Endothelial dysfunction is an early predictor of atherosclerosis and future cardiovascular events. We review the prognostic value of obtaining measurements of endothelial function, the clinical techniques for its determination, the mechanisms leading to endothelial dysfunction and the therapeutic treatment of endothelial dysfunction. Since vascular oxidative stress and inflammation are major determinants of endothelial function, we have also addressed current antioxidant and anti-inflammatory therapies. In the light of recent data that dispute the prognostic value of endothelial function in healthy human cohorts, we also discuss alternative diagnostic parameters such as vascular stiffness index and intima/media thickness ratio. We also suggest that assessing vascular function, including that of smooth muscle and even perivascular adipose tissue, may be an appropriate parameter for clinical investigations.

LINKED ARTICLES

This article is part of a themed section on Redox Biology and Oxidative Stress in Health and Disease. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.12/issuetoc.

Entacapone is an Antioxidant More Potent than Vitamin C and Vitamin E for Scavenging of Hypochlorous Acid and Peroxynitrite, and the Inhibition of Oxidative Stress-Induced Cell Death

Background

Entacapone (ENT), a clinical drug for the treatment of Parkinson’s disease, has been shown to have antioxidant effects, but little is known about its antioxidant mechanisms. The objective of the current study was to determine the antioxidant activity of ENT against different species of oxidants and compared it with that of vitamin C and vitamin E. We also determined the effect of ENT on oxidative stress-induced cell death in human umbilical vein endothelial cells (HUVECs).

Material/Methods

The total antioxidant activities of ENT, vitamin C and vitamin E were determined with a standard DPPH-scavenging assay. Specific assays to determine ENT’s scavenging activity on hypochlorous acid (HOCl), peroxynitrite (ONOO⁻), and hydrogen peroxide (H₂O₂), and the chelating effect on Fe(II) were used. H₂O₂-induced cell death in HUVECs was determined with the MTT assay.

Results

ENT (10 and 20 μM) scavenged 60% and 83% of DPPH activity, respectively. These percentages were greater than those resulting from using the same concentrations of vitamin C and vitamin E. ENT’s HOCl-scavenging activity was concentration-dependent and 8 to 20 times stronger than those of vitamin C and vitamin E. ENT’s ONOO⁻-scavenging activity was 8% to 30% stronger than that of vitamin C. However, ENT, vitamin C, and vitamin E were not able to directly scavenge H₂O₂, and did not show any chelating effect on Fe(II). Importantly ENT, but not vitamin C or vitamin E, inhibited H₂O₂-induced cell death in HUVECs.

Conclusions

ENT is an antioxidant that can scavenge toxic HOCl and ONOO⁻ species and inhibit oxidative stress-induced cell death more effectively than vitamin C and vitamin E. ENT may have new clinical applications as an antioxidant in the treatment of ROS-induced diseases including cardiovascular disease, cancer, and neurodegenerative diseases.