Short-term use of telmisartan attenuates oxidation and improves Prdx2 expression more than antioxidant β-blockers in the cardiovascular systems of spontaneously hypertensive rats

Serum Malondialdehyde Levels in Hypertensive Patients: A Non-invasive Marker of Oxidative Stress. A Systematic Review and Meta-analysis

INTRODUCTION

Previous analyses have reported a higher malondialdehyde (MDA) serum level in hypertensive patients (HTs) compared to normotensive subjects (NTs).

AIM

We performed a systematic review and meta-analysis of these studies to offer a comprehensive information on this issue.

METHODS

The PubMed, EMBASE and Web of Science databases were analysed to locate English-language articles published from January 1, 2000 up to January 1 2021. Studies were identified using the following MeSH terms: "Malondialdehyde" AND "Arterial hypertension". The difference of MDA serum levels between HTs and NTs was expressed as standardized mean difference (SMD) with 95% CI using a random-effect model.

RESULTS

A total of of 4102 patients (2158 HTs and 1944 NTs, mean age 52.7 and 48.0 years, respectively) were included in 17 studies. Pooled mean MDA serum levels in HTs and NTs were 4.91 [standard error (SE): 0.34, 95% CI 4.23-5.59)] and 3.43 [SE 0.15, 95% CI 3.18-3.78] nmol/L, respectively. The SMD between HTs and NTs was 3.23 nmol/L (95% CI 2.54-3.92; Z-score for overall effect: 9.17, p < 0.0001, I² = 98.6%). Egger's test resulted significant at p = 0.009 while Begg's test was not, p = 0.11. Subsequent adjustment via the trim-and-fill method did not predict a new model (studies trimmed = 0). Meta-regression analysis found no correlations either between SMD and age (p = 0.95) or BMI (p = 0.96) but a significant one considering the latitude of the study site as moderator variable (p = 0.001).

CONCLUSIONS

Among patients with HTs, serum MDA appears to have the greatest potential as non-invasive biomarkers of oxidative stress and endothelial dysfunction (ED).

Telmisartan alleviates alcohol-induced liver injury by activation of PPAR-γ/ Nrf-2 crosstalk in mice

Excessive consumption of alcohol may induce severe liver damage, in part via oxidative stress and inflammatory responses, which implicates these processes as potential therapeutic approaches. Prior literature has shown that Telmisartan (TEL) may provide protective effects, presumably mediated by its anti-oxidant and anti-inflammatory activities. The purpose of this study was to determine TEL's hepatoprotective effects and to identify its possible curative mechanisms in alcoholic liver disease. A mouse chronic alcohol plus binge feedings model was used in the current study for induction of alcoholic liver disease (ALD). Our results showed that TEL (10 mg/kg/day) has the ability to reduce serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (ALP). TEL also increased the activity of superoxide dismutase (SOD) and glutathione (GSH) with concomitant reduction of nitric oxide (NO) malonaldehyde (MDA) in the liver homogenate. Moreover, TEL downregulated nuclear factor kappa B (NF-κB) expression and decreased liver content of interleukin-6 (IL-6), interleukin-1β (IL-1β), and tumor necrosis factor-α (TNF-α). These anti-inflammatory and anti-oxidant activities were associated with a significant increase in the expression of nuclear factor erythroid 2-related factor 2 (Nrf-2), peroxisome proliferator-activated receptors -γ (PPAR-γ), and heme oxygenase-1 (Hmox-1). In conclusion, TEL's hepatoprotective effects against ALD may be attributable to its anti-inflammatory and anti-oxidant activities which may be in part via the modulation of PPAR-γ/ Nrf-2/ NF-κB crosstalk.

Angiotensin II Attenuates the Bioactivities of Human Endothelial Progenitor Cells via Downregulation of β2-Adrenergic Receptor

Cross talks between the renin-angiotensin system (RAS), sympathetic nervous system, and vascular homeostasis are tightly coordinated in hypertension. Angiotensin II (Ang II), a key factor in RAS, when abnormally activated, affects the number and bioactivity of circulating human endothelial progenitor cells (hEPCs) in hypertensive patients. In this study, we investigated how the augmentation of Ang II regulates adrenergic receptor-mediated signaling and angiogenic bioactivities of hEPCs. Interestingly, the short-term treatment of hEPCs with Ang II drastically attenuated the expression of beta-2 adrenergic receptor (ADRB2), but did not alter the expression of beta-1 adrenergic receptor (ADRB1) and Ang II type 1 receptor (AT1R). EPC functional assay clearly demonstrated that the treatment with ADRB2 agonists significantly increased EPC bioactivities including cell proliferation, migration, and tube formation abilities. However, EPC bioactivities were decreased dramatically when treated with Ang II. Importantly, the attenuation of EPC bioactivities by Ang II was restored by treatment with an AT1R antagonist (telmisartan; TERT). We found that AT1R binds to ADRB2 in physiological conditions, but this binding is significantly decreased in the presence of Ang II. Furthermore, TERT, an Ang II-AT1R interaction blocker, restored the interaction between AT1R and ADRB2, suggesting that Ang II might induce the dysfunction of EPCs via downregulation of ADRB2, and an AT1R blocker could prevent Ang II-mediated ADRB2 depletion in EPCs. Taken together, our report provides novel insights into potential therapeutic approaches for hypertension-related cardiovascular diseases.

Galectin-3 down-regulates antioxidant peroxiredoxin-4 in human cardiac fibroblasts: a new pathway to induce cardiac damage

Galectin-3 (Gal-3) is increased in heart failure (HF) and promotes cardiac fibrosis and inflammation. We investigated whether Gal-3 modulates oxidative stress in human cardiac fibroblasts, in experimental animal models and in human aortic stenosis (AS). Using proteomics and immunodetection approaches, we have identified that Gal-3 down-regulated the antioxidant peroxiredoxin-4 (Prx-4) in cardiac fibroblasts. In parallel, Gal-3 increased peroxide, nitrotyrosine, malondialdehyde, and N-carboxymethyl-lysine levels and decreased total antioxidant capacity. Gal-3 decreased prohibitin-2 expression without modifying other mitochondrial proteins. Prx-4 silencing increased oxidative stress markers. In Gal-3-silenced cells and in heart from Gal-3 knockout mice, Prx-4 was increased and oxidative stress markers were decreased. Pharmacological inhibition of Gal-3 with modified citrus pectin restored cardiac Prx-4 as well as prohibitin-2 levels and improved oxidative status in spontaneously hypertensive rats. In serum from 87 patients with AS, Gal-3 negatively correlated with total antioxidant capacity and positively correlated with peroxide. In myocardial biopsies from 26 AS patients, Gal-3 up-regulation paralleled a decrease in Prx-4 and in prohibitin-2. Cardiac Gal-3 inversely correlated with Prx-4 levels in myocardial biopsies. These data suggest that Gal-3 decreased Prx-4 antioxidant system in cardiac fibroblasts, increasing oxidative stress. In pathological models presenting enhanced cardiac Gal-3, the decrease in Prx-4 expression paralleled increased oxidative stress. Gal-3 blockade restored Prx-4 expression and improved oxidative stress status. In AS, circulating levels of Gal-3 could reflect oxidative stress. The alteration of the balance between antioxidant systems and reactive oxygen species production could be a new pathogenic mechanism by which Gal-3 induces cardiac damage in HF.

Telmisartan protects chronic intermittent hypoxic mice via modulating cardiac renin-angiotensin system activity

BACKGROUND

To explore the effects of chronic intermittent hypoxia (CIH), which mimics sleep apnea syndrome, on the cardiac renin angiotensin system (RAS), and to investigate the cardiac protection of an angiotensin receptor blocker (ARB)telmisartan (TERT) against CIH.

METHODS

32 healthy male C57B6J mice were randomly divided into CIH, ARB, blank and air control groups. CIH lasted for 12 weeks. Cardiac angiotensin converting enzyme (ACE), angiotensin converting enzyme 2 (ACE 2) and angiotensin II (Ang II) were evaluated by immunohistochemistry. Myocardial apoptosis were assessed by TUNEL assay and myocardial cell ultrastructure were observed under transmission electron microscope.

RESULTS

Cardiac ACE expression was higher in the CIH group than in blank and air control groups, which was decreased with TERT treatment. TERT treatment elevated the expression of cardiac ACE 2 and Ang II compared with CIH group. Myocardial cell and capillary endothelial cell apoptosis, mitochondrial injury were most severe in CIH groups, which were mitigated with TERT treatment.

CONCLUSIONS

CIH changes the expression of cardiac ACE, ACE2 and Ang II, which may cause myocardial damage. TERT protects mice from CIH-linked cardiac damage via modulating the activity of RAS in the hearts.

Modulation of cardiac stem cell characteristics by metoprolol in hypertensive heart disease

Cardiac stem cells (CSCs) play a vital role in cardiac remodeling. Uncontrolled hypertension leads to cardiac hypertrophy, followed by cardiac failure. Pathological remodeling is associated with enhanced oxidative stress. Decreased cardiac stem cell efficiency is speculated in heart diseases. Maintaining a healthy stem cell population is essential for preventing progressive cardiac remodeling. Some anti-hypertensive drugs are cardioprotective. However, the effect of these drugs on CSCs has not been investigated. Metoprolol is a cardioprotective anti-hypertensive agent. To examine whether metoprolol can prevent the deterioration of CSC efficiency, spontaneously hypertensive rats (SHRs) were treated with this drug, and the effects on stem cell function were evaluated. Six-month-old male SHRs were treated with metoprolol (50 mg × kg^-1per day) for 2 months. The effectiveness of the treatment at reducing blood pressure and reducing hypertrophy was ensured, and the animals were killed. Cardiac stem cells were isolated from the atrial tissue, and the effect of metoprolol on stem cell migration, proliferation, differentiation, and survival was evaluated by comparing the treated SHRs with untreated SHRs and normotensive Wistar rats. Compared to the Wistar rats, the SHR rats presented with a decrease in stem cell migration and proliferation and an increase in intracellular oxidative stress and senescence. Treating SHRs with metoprolol increased CSC migration and proliferation potential and stemness retention. Cellular senescence and oxidative stress were reduced. The attributes of stem cells from the metoprolol-treated SHRs were comparable to those of the Wistar rats. The restoration of stem cell efficiency is expected to prevent hypertension-induced progressive cardiac remodeling.

Enhanced Mitochondrial Transient Receptor Potential Channel, Canonical Type 3-Mediated Calcium Handling in the Vasculature From Hypertensive Rats

BACKGROUND

Mitochondrial Ca2+ homeostasis is fundamental to the regulation of mitochondrial reactive oxygen species (ROS) generation and adenosine triphosphate production. Recently, transient receptor potential channel, canonical type 3 (TRPC3), has been shown to localize to the mitochondria and to play a role in maintaining mitochondrial calcium homeostasis. Inhibition of TRPC3 attenuates vascular calcium influx in spontaneously hypertensive rats (SHRs). However, it remains elusive whether mitochondrial TRPC3 participates in hypertension by increasing mitochondrial calcium handling and ROS production.

METHODS AND RESULTS

In this study we demonstrated increased TRPC3 expression in purified mitochondria in the vasculature from SHRs, which facilitates enhanced mitochondrial calcium uptake and ROS generation compared with Wistar-Kyoto rats. Furthermore, inhibition of TRPC3 by its specific inhibitor, Pyr3, significantly decreased the vascular mitochondrial ROS production and H2O2 synthesis and increased adenosine triphosphate content. Administration of telmisartan can improve these abnormalities. This beneficial effect was associated with improvement of the mitochondrial respiratory function through recovering the activity of pyruvate dehydrogenase in the vasculature of SHRs. In vivo, chronic administration of telmisartan suppressed TRPC3-mediated excessive mitochondrial ROS generation and vasoconstriction in the vasculature of SHRs. More importantly, TRPC3 knockout mice exhibited significantly ameliorated hypertension through reduction of angiotensin II-induced mitochondrial ROS generation.

CONCLUSIONS

Together, we give experimental evidence for a potential mechanism by which enhanced TRPC3 activity at the cytoplasmic and mitochondrial levels contributes to redox signaling and calcium dysregulation in the vasculature from SHRs. Angiotensin II or telmisartan can regulate [Ca2+]mito, ROS production, and mitochondrial energy metabolism through targeting TRPC3.

Protective effects of telmisartan and tempol on lipopolysaccharide-induced cognitive impairment, neuroinflammation, and amyloidogenesis: possible role of brain-derived neurotrophic factor

Angiotensin II has pro-inflammatory and pro-oxidant potentials. We investigated the possible protective effects of the Angiotensin II receptor blocker telmisartan, compared with the superoxide scavenger tempol, on lipopolysaccharide (LPS)-induced cognitive decline and amyloidogenesis. Briefly, mice were allocated into a normal control group, an LPS control group, a tempol treatment group, and 2 telmisartan treatment groups. A behavioral study was conducted followed by a biochemical study via assessment of brain levels of beta amyloid (Aβ) and brain-derived neurotropic factor (BDNF) as amyloidogenesis and neuroplasticity markers, tumor necrosis factor alpha (TNF-α), nitric oxide end products (NOx), neuronal and inducible nitric oxide synthase (nNOS and iNOS) as inflammatory markers, and superoxide dismutase (SOD), malondialdehyde (MDA), glutathione reduced (GSH), and nitrotyrosine (NT) as oxido-nitrosative stress markers. Finally, histopathological examination of cerebral cortex, hippocampus, and cerebellum sections was performed using routine and special Congo red stains. Tempol and telmisartan improved cognition, decreased brain Aβ deposition and BDNF depletion, decreased TNF-α, NOx, nNOS, iNOS, MDA, and NT brain levels, and increased brain SOD and GSH contents, parallel to confirmatory histopathological evidences. In conclusion, tempol and telmisartan are promising drugs in managing cognitive impairment and amyloidogenesis, at least via upregulation of BDNF with inhibition of neuroinflammation and oxido-nitrosative stress.

Vascular structural and functional changes: their association with causality in hypertension: models, remodeling and relevance

Essential hypertension is a complex multifactorial disease process that involves the interaction of multiple genes at various loci throughout the genome, and the influence of environmental factors such as diet and lifestyle, to ultimately determine long-term arterial pressure. These factors converge with physiological signaling pathways to regulate the set-point of long-term blood pressure. In hypertension, structural changes in arteries occur and show differences within and between vascular beds, between species, models and sexes. Such changes can also reflect the development of hypertension, and the levels of circulating humoral and vasoactive compounds. The role of perivascular adipose tissue in the modulation of vascular structure under various disease states such as hypertension, obesity and metabolic syndrome is an emerging area of research, and is likely to contribute to the heterogeneity described in this review. Diversity in structure and related function is the norm, with morphological changes being causative in some beds and states, and in others, a consequence of hypertension. Specific animal models of hypertension have advantages and limitations, each with factors influencing the relevance of the model to the human hypertensive state/s. However, understanding the fundamental properties of artery function and how these relate to signalling mechanisms in real (intact) tissues is key for translating isolated cell and model data to have an impact and relevance in human disease etiology. Indeed, the ultimate aim of developing new treatments to correct vascular dysfunction requires understanding and recognition of the limitations of the methodologies used.

Aliskiren and l-arginine treatments restore depressed baroreflex sensitivity and decrease oxidative stress in renovascular hypertension rats

Renovascular hypertension is characterized by increased angiotensin II and oxidative stress, and by endothelial dysfunction. The purpose of this study was to test whether the administration of aliskiren (ALSK) and l-arginine (l-ARG) would restore impaired baroreflex sensitivity and reduce oxidative stress in a rat renovascular hypertension model. Hypertension was induced by clipping the left renal artery, and the following five groups were created: SHAM; two-kidney, 1-clip (2K1C); 2K1C plus ALSK (ALSK); 2K1C plus l-ARG (l-ARG); and 2K1C plus ALSK+l-ARG (ALSK+l-ARG). After 21 days of treatment, only the ALSK+l-ARG group was effective in normalizing the arterial pressure (108.8±2.8 mm Hg). The l-ARG and ALSK+l-ARG groups did not show hypertrophy of the left ventricle. All the treatments restored the depressed baroreflex sensitivity to values found in the SHAM group. Acute administration of TEMPOL restored the depressed baroreflex sensitivity in the 2K1C group to values that resembled those presented by the other groups. All treatments were effective for an increase in the antioxidant pathway and reduction in the oxidative pathway. In conclusion, the treatment with ALSK or l-ARG reduced oxidative stress and restored reduced baroreflex sensitivity in renovascular hypertension. In addition, the treatments were able to normalize blood pressure and reverse left ventricular hypertrophy when used in combination.

Angiotensin II type 1 receptor antagonists in animal models of vascular, cardiac, metabolic and renal disease

We have reviewed the effects of angiotensin II type 1 receptor antagonists (ARBs) in various animal models of hypertension, atherosclerosis, cardiac function, hypertrophy and fibrosis, glucose and lipid metabolism, and renal function and morphology. Those of azilsartan and telmisartan have been included comprehensively whereas those of other ARBs have been included systematically but without intention of completeness. ARBs as a class lower blood pressure in established hypertension and prevent hypertension development in all applicable animal models except those with a markedly suppressed renin-angiotensin system; blood pressure lowering even persists for a considerable time after discontinuation of treatment. This translates into a reduced mortality, particularly in models exhibiting marked hypertension. The retrieved data on vascular, cardiac and renal function and morphology as well as on glucose and lipid metabolism are discussed to address three main questions: 1. Can ARB effects on blood vessels, heart, kidney and metabolic function be explained by blood pressure lowering alone or are they additionally directly related to blockade of the renin-angiotensin system? 2. Are they shared by other inhibitors of the renin-angiotensin system, e.g. angiotensin converting enzyme inhibitors? 3. Are some effects specific for one or more compounds within the ARB class? Taken together these data profile ARBs as a drug class with unique properties that have beneficial effects far beyond those on blood pressure reduction and, in some cases distinct from those of angiotensin converting enzyme inhibitors. The clinical relevance of angiotensin receptor-independent effects of some ARBs remains to be determined.

Abnormal correlation of circulating endothelial progenitor cells and endothelin-1 concentration may contribute to the development of arterial hypertension in childhood acute lymphoblastic leukemia survivors

It is well known that the rate of arterial hypertension (AH) in childhood acute lymphoblastic leukemia (ALL) survivors is significantly higher than that in the healthy pediatric population; however, the mechanism of this phenomenon is not fully understood. The developing cardiovascular system in children is thought to be highly susceptible to the toxic effects of chemotherapy, which causes damage to the blood vessel wall, including the endothelium. Endothelin-1 (ET-1) is a marker of endothelial damage, and it contributes to AH. Endothelial progenitor cells (EPCs) are derived from the bone marrow and participate in the process of blood vessel repair. The aim of this study was to determine the relationship between the rate of circulating EPCs and plasma levels of ET-1 with respect to hypertension in childhood ALL survivors. The study included 88 childhood ALL survivors and 44 healthy children as controls. All patients and controls had 24-h blood pressure monitoring with a HolCARD CR-07 device. The number of EPCs and the ET-1 serum concentration were measured in the peripheral blood of patients and controls using flow cytometry and enzyme-linked immunosorbent assay, respectively. A correlation was found between the number of EPCs and the ET-1 concentration in the peripheral blood of healthy children and normotensive ALL survivors. However, such a correlation was not found in hypertensive childhood ALL survivors. We conclude that dysregulation of the 'ET-1 and EPC axis' may contribute to the development of AH in some childhood ALL survivors.

Biomarkers of lipid peroxidation related to hypertension in aging

The aim of this clinical study was to evaluate the influence of aging on the levels of lipid peroxidation (quantified as thiobarbituric acid-reactive substances (TBARS) content), lipid hydroperoxide (LOOH), hexanoyl lysine (HEL), 8-iso-prostaglandin F2α (8-iso-PGF2α) and total antioxidant capacity (TAC), and determine their relationships to the demographic and cardiovascular risk factors in elderly hypertensive (HT) patients. This study consisted of four groups: two elderly groups with 30 HT patients (11 males, 19 females) and 30 normotensive healthy volunteers (15 males, 15 females), and two young groups with 30 HT patients (13 males, 17 females) and 30 normotensive healthy volunteers (12 males, 18 females). In the elderly control group, the TBARS, LOOH, HEL and 8-iso-PGF2α levels, and the carotid intima media thickness (CIMT) were significantly higher than in the young control group. The TBARS, LOOH, HEL and 8-iso-PGF2α levels and the CIMT measurements were significantly higher in the elderly HT group than in the young HT group. In addition, the TAC levels were significantly lower in the elderly and young HT groups than in the elderly and young control groups. The CIMT was significantly positively correlated with TBARS (r=0.40, P<0.001), HEL (r= 0.30, P=0.001), LOOH (r= 0.44, P<0.001) and 8-iso-PGF2α (r= 0.32, P<0.001) in all of the HT groups. It seems that in elderly patients, the LOOH and TBARS are better biomarkers of lipid peroxidation in hypertension in terms of sensitivity. In all of the HT groups, 8-iso-PGF2α had the highest sensitivity. Hypertension is associated with lipid peroxidation due to an impaired oxidant/antioxidant status. Increased lipid peroxidation and decreased antioxidants with aging indicate that peroxidative damage further increases with higher blood pressure and the aging process.