Vascular oxidative stress upregulates angiotensin II type I receptors via mechanisms involving nuclear factor kappa B

Aging and "Age-Related" Diseases - What Is the Relation?

The study explores the intricate relationship between aging and the development of noncommunicable diseases [NCDs], focusing on whether these diseases are inevitable consequences of aging or primarily driven by lifestyle factors. By examining epidemiological data, particularly from hunter-gatherer societies, the study highlights that many NCDs prevalent in modern populations are rare in these societies, suggesting a significant influence of lifestyle choices. It delves into the mechanisms through which poor diet, smoking, and other lifestyle factors contribute to systemic physiological imbalances, characterized by oxidative stress, insulin resistance and hyperinsulinemia, and dysregulation of the sympathetic nervous system, the renin-angiotensin-aldosterone system, and the immune system. The interplay between this pattern and individual factors such as genetic susceptibility, biological variability, epigenetic changes and the microbiome is proposed to play a crucial role in the development of a range of age-related NCDs. Modified biomolecules such as oxysterols and advanced glycation end products also contribute to their development. Specific diseases such as benign prostatic hyperplasia, Parkinson's disease, glaucoma and osteoarthritis are analyzed to illustrate these mechanisms. The study concludes that while aging contributes to the risk of NCDs, lifestyle factors play a crucial role, offering potential avenues for prevention and intervention through healthier living practices. One possible approach could be to try to restore the physiological balance, e.g. through dietary measures [e.g. Mediterranean diet, Okinawan diet or Paleolithic diet] in conjunction with [a combination of] pharmacological interventions and other lifestyle changes.

Iron chelation suppresses secondary bleeding after intracerebral hemorrhage in angiotensin II-infused mice

AIMS

Secondary bleeding and further hematoma expansion (HE) aggravate brain injury after intracerebral hemorrhage (ICH). The majority of HE results from hypertensive ICH. Previous study reported higher iron content in the brains of hypertensive patients. Iron overload exacerbates the risk of hemorrhagic transformation in thromboembolic stroke mice. Whether iron overload during the process of hypertension participates in secondary bleeding of hypertensive ICH remains unclear.

METHODS

Hypertension was induced by continuous infusion of angiotensin II (Ang II) with an osmotic pump into C57BL/6 mice. ICH was simulated by intrastriatal injection of the liquid polymer Onyx-18. Iron chelation and iron overload was achieved by deferoxamine mesylate or iron dextran injection. Secondary bleeding was quantified by measuring the hemoglobin content in the ipsilateral brain hemisphere.

RESULTS

Ang II-induced hypertensive mice showed increased iron accumulation in the brain and expanded secondary hemorrhage after ICH modeling. Moreover, iron chelation suppressed while iron overload aggravated secondary bleeding. Mechanistically, iron exacerbated the loss of contractile cerebral vascular smooth muscle cells (VSMCs), aggravated blood-brain barrier (BBB) leakage in Ang II-induced hypertensive mice, and increased glial and MMP9 accumulation after ICH.

CONCLUSION

Iron overload plays a key role in secondary bleeding after ICH in Ang II-induced hypertensive mice. Iron chelation during the process of Ang II-induced hypertension suppresses secondary bleeding after ICH.

Jares E, Jarvis D, Jassem E, Jenko K, Jiméneracruz Uscanga RD, Johnston SL, Joos G, Jošt M, Julge K, Jung K, Just J, Jutel M, Kaidashev I, Kalayci O, Kalyoncu F, Kapsali J, Kardas P, Karjalainen J, Kasala CA, Katotomichelakis M, Kavaliukaite L, Kazi BS, Keil T, Keith P, Khaitov M, Khaltaev N, Kim Y, Kirenga B, Kleine‐Tebbe J, Klimek L, Koffi N’Goran B, Kompoti E, Kopač P, Koppelman G, KorenJeverica A, Koskinen S, Košnik M, Kostov KV, Kowalski ML, Kralimarkova T, Kramer Vrščaj K, Kraxner H, Kreft S, Kritikos V, Kudlay D, Kuitunen M, Kull I, Kuna P, Kupczyk M, Kvedariene V, Kyriakakou M, Lalek N, Landi M, Lane S, Larenas‐Linnemann D, Lau S, Laune D, Lavrut J, Le L, Lenzenhuber M, Lessa M, Levin M, Li J, Lieberman P, Liotta G, Lipworth B, Liu X, Lobo R, Lodrup Carlsen KC, Lombardi C, Louis R, Loukidis S, Lourenço O, Luna Pech JA, Madjar B, Maggi E, Magnan A, Mahboub B, Mair A, Mais Y, Maitland van der Zee A, Makela M, Makris M, Malling H, Mandajieva M, Manning P, Manousakis M, Maragoudakis P, Marseglia G, Marshall G, Reza Masjedi M, Máspero JF, Matta Campos JJ, Maurer M, Mavale‐Manuel S, Meço C, Melén E, Melioli G, Melo‐Gomes E, Meltzer EO, Menditto E, Menzies‐Gow A, Merk H, Michel J, Micheli Y, Miculinic N, Midão L, Mihaltan F, Mikos N, Milanese M, Milenkovic B, Mitsias D, Moalla B, Moda G, Mogica Martínez MD, Mohammad Y, Moin M, Molimard M, Momas I, Mommers M, Monaco A, Montefort S, Mora D, Morais‐Almeida M, Mösges R, Mostafa B, Mullol J, Münter L, Muraro A, Murray R, Musarra A, Mustakov T, Naclerio R, Nadeau KC, Nadif R, Nakonechna A, Namazova‐Baranova L, Navarro‐Locsin G, Neffen H, Nekam K, Neou A, Nettis E, Neuberger D, Nicod L, Nicola S, Niederberger‐Leppin V, Niedoszytko M, Nieto A, Novellino E, Nunes E, Nyembue D, O’Hehir R, Odjakova C, Ohta K, Okamoto Y, Okubo K, Oliver B, Onorato GL, Pia Orru M, Ouédraogo S, Ouoba K, Paggiaro PL, Pagkalos A, Pajno G, Pala G, Palaniappan S, Pali‐Schöll I, Palkonen S, Palmer S, Panaitescu Bunu C, Panzner P, Papadopoulos NG, Papanikolaou V, Papi A, Paralchev B, Paraskevopoulos G, Park H, Passalacqua G, Patella V, Pavord I, Pawankar R, Pedersen S, Peleve S, Pellegino S, Pereira A, Pérez T, Perna A, Peroni D, Pfaar O, Pham‐Thi N, Pigearias B, Pin I, Piskou K, Pitsios C, Plavec D, Poethig D, Pohl W, Poplas Susic A, Popov TA, Portejoie F, Potter P, Poulsen L, Prados‐Torres A, Prarros F, Price D, Prokopakis E, Puggioni F, Puig‐Domenech E, Puy R, Rabe K, Raciborski F, Ramos J, Recto MT, Reda SM, Regateiro FS, Reider N, Reitsma S, Repka‐Ramirez S, Ridolo E, Rimmer J, Rivero Yeverino D, Angelo Rizzo J, Robalo‐Cordeiro C, Roberts G, Roche N, Rodríguez González M, Rodríguez Zagal E, Rolla G, Rolland C, Roller‐Wirnsberger R, Roman Rodriguez M, Romano A, Romantowski J, Rombaux P, Romualdez J, Rosado‐Pinto J, Rosario N, Rosenwasser L, Rossi O, Rottem M, Rouadi P, Rovina N, Rozman Sinur I, Ruiz M, Ruiz Segura LT, Ryan D, Sagara H, Sakai D, Sakurai D, Saleh W, Salimaki J, Samitas K, Samolinski B, Sánchez Coronel MG, Sanchez‐Borges M, Sanchez‐Lopez J, Sarafoleanu C, Sarquis Serpa F, Sastre‐Dominguez J, Savi E, Sawaf B, Scadding GK, Scheire S, Schmid‐Grendelmeier P, Schuhl JF, Schunemann H, Schvalbová M, Schwarze J, Scichilone N, Senna G, Sepúlveda C, Serrano E, Shields M, Shishkov V, Siafakas N, Simeonov A, FER Simons E, Carlos Sisul J, Sitkauskiene B, Skrindo I, SokličKošak T, Solé D, Sooronbaev T, Soto‐Martinez M, Soto‐Quiros M, Sousa Pinto B, Sova M, Soyka M, Specjalski K, Spranger O, Stamataki S, Stefanaki L, Stellato C, Stelmach R, Strandberg T, Stute P, Subramaniam A, Suppli Ulrik C, Sutherland M, Sylvestre S, Syrigou A, Taborda Barata L, Takovska N, Tan R, Tan F, Tan V, Ping Tang I, Taniguchi M, Tannert L, Tantilipikorn P, Tattersall J, Tesi F, Thijs C, Thomas M, To T, Todo‐Bom A, Togias A, Tomazic P, Tomic‐Spiric V, Toppila‐Salmi S, Toskala E, Triggiani M, Triller N, Triller K, Tsiligianni I, Uberti M, Ulmeanu R, Urbancic J, Urrutia Pereira M, Vachova M, Valdés F, Valenta R, Valentin Rostan M, Valero A, Valiulis A, Vallianatou M, Valovirta E, Van Eerd M, Van Ganse E, Hage M, Vandenplas O, Vasankari T, Vassileva D, Velasco Munoz C, Ventura MT, Vera‐Munoz C, Vicheva D, Vichyanond P, Vidgren P, Viegi G, Vogelmeier C, Von Hertzen L, Vontetsianos T, Vourdas D, Tran Thien Quan V, Wagenmann M, Walker S, Wallace D, Wang DY, Waserman S, Wickman M, Williams S, Williams D, Wilson N, Wong G, Woo K, Wright J, Wroczynski P, Xepapadaki P, Yakovliev P, Yamaguchi M, Yan K, Yeow Yap Y, Yawn B, Yiallouros P, Yorgancioglu A, Yoshihara S, Young I, Yusuf OB, Zaidi A, Zaitoun F, Zar H, Zedda M, Zernotti ME, Zhang L, Zhong N, Zidarn M, Zubrinich C. Cabbage and fermented vegetables: From death rate heterogeneity in countries to candidates for mitigation strategies of severe COVID-19

Large differences in COVID‐19 death rates exist between countries and between regions of the same country. Some very low death rate countries such as Eastern Asia, Central Europe, or the Balkans have a common feature of eating large quantities of fermented foods. Although biases exist when examining ecological studies, fermented vegetables or cabbage have been associated with low death rates in European countries. SARS‐CoV‐2 binds to its receptor, the angiotensin‐converting enzyme 2 (ACE2). As a result of SARS‐CoV‐2 binding, ACE2 downregulation enhances the angiotensin II receptor type 1 (AT₁R) axis associated with oxidative stress. This leads to insulin resistance as well as lung and endothelial damage, two severe outcomes of COVID‐19. The nuclear factor (erythroid‐derived 2)‐like 2 (Nrf2) is the most potent antioxidant in humans and can block in particular the AT₁R axis. Cabbage contains precursors of sulforaphane, the most active natural activator of Nrf2. Fermented vegetables contain many lactobacilli, which are also potent Nrf2 activators. Three examples are: kimchi in Korea, westernized foods, and the slum paradox. It is proposed that fermented cabbage is a proof‐of‐concept of dietary manipulations that may enhance Nrf2‐associated antioxidant effects, helpful in mitigating COVID‐19 severity.

Inhibition of plasma kallikrein mitigates experimental hypertension-enhanced cerebral hematoma expansion

RATIONALE

Hematoma expansion (HE) aggravates brain injury after intracerebral hemorrhage (ICH) and hypertension is a key contributor to HE. Plasma kallikrein (PK) is involved in hemorrhagic transformation in ischemic stroke mice. This study was conducted to explore the role of PK in HE in hypertensive ICH.

METHODS

Hypertension was achieved by continuous infusion of angiotensin II (Ang II) with an osmotic pump in C57BL/6 mice. ICH was achieved by stereotactic intrastriatal injection of blood. PK-specific antibody and platelet glycoprotein VI (GPVI) agonists were administered to intervene in hematoma expansion. The hematoma volume was indicated by the erythrocyte components hemoglobin and carbonic anhydrase-1 in the ipsilateral brain hemisphere.

RESULTS

Ang II-induced hypertensive mice showed enhanced hematoma expansion and worsened neurologic deficits after ICH modeling. Moreover, intrastriatal injection of blood from Ang II-treated mice into normal mice increased the area of secondary hemorrhage more than blood from untreated mice. Mechanistically, elevated PK was found in Ang II-infused mice whereas, inhibition of PK and administration of the GPVI agonist convulxin decreased hematoma expansion and improved neurologic deficits after ICH.

CONCLUSIONS

These findings suggest that PK inhibition and GPVI agonist treatment might serve as potential methods to intervene in HE after ICH.

Nrf2-interacting nutrients and COVID-19: time for research to develop adaptation strategies

There are large between- and within-country variations in COVID-19 death rates. Some very low death rate settings such as Eastern Asia, Central Europe, the Balkans and Africa have a common feature of eating large quantities of fermented foods whose intake is associated with the activation of the Nrf2 (Nuclear factor (erythroid-derived 2)-like 2) anti-oxidant transcription factor. There are many Nrf2-interacting nutrients (berberine, curcumin, epigallocatechin gallate, genistein, quercetin, resveratrol, sulforaphane) that all act similarly to reduce insulin resistance, endothelial damage, lung injury and cytokine storm. They also act on the same mechanisms (mTOR: Mammalian target of rapamycin, PPARγ:Peroxisome proliferator-activated receptor, NFκB: Nuclear factor kappa B, ERK: Extracellular signal-regulated kinases and eIF2α:Elongation initiation factor 2α). They may as a result be important in mitigating the severity of COVID-19, acting through the endoplasmic reticulum stress or ACE-Angiotensin-II-AT₁R axis (AT₁R) pathway. Many Nrf2-interacting nutrients are also interacting with TRPA1 and/or TRPV1. Interestingly, geographical areas with very low COVID-19 mortality are those with the lowest prevalence of obesity (Sub-Saharan Africa and Asia). It is tempting to propose that Nrf2-interacting foods and nutrients can re-balance insulin resistance and have a significant effect on COVID-19 severity. It is therefore possible that the intake of these foods may restore an optimal natural balance for the Nrf2 pathway and may be of interest in the mitigation of COVID-19 severity.

Antioxidant Effects of PS5, a Peptidomimetic of Suppressor of Cytokine Signaling 1, in Experimental Atherosclerosis

The chronic activation of the Janus kinase/signal transducer and activator of the transcription (JAK/STAT) pathway is linked to oxidative stress, inflammation and cell proliferation. Suppressors of cytokine signaling (SOCS) proteins negatively regulate the JAK/STAT, and SOCS1 possesses a small kinase inhibitory region (KIR) involved in the inhibition of JAK kinases. Several studies showed that KIR-SOCS1 mimetics can be considered valuable therapeutics in several disorders (e.g., diabetes, neurological disorders and atherosclerosis). Herein, we investigated the antioxidant and atheroprotective effects of PS5, a peptidomimetic of KIR-SOCS1, both in vitro (vascular smooth muscle cells and macrophages) and in vivo (atherosclerosis mouse model) by analyzing gene expression, intracellular O₂^•− production and atheroma plaque progression and composition. PS5 was revealed to be able to attenuate NADPH oxidase (NOX1 and NOX4) and pro-inflammatory gene expression, to upregulate antioxidant genes and to reduce atheroma plaque size, lipid content and monocyte/macrophage accumulation. These findings confirm that KIR-SOCS1-based drugs could be excellent antioxidant agents to contrast atherosclerosis.

The natural drug DIAVIT is protective in a type II mouse model of diabetic nephropathy

There is evidence to suggest that abnormal angiogenesis, inflammation, and fibrosis drive diabetic nephropathy (DN). However, there is no specific treatment to counteract these processes. We aimed to determine whether DIAVIT, a natural Vaccinium myrtillus (blueberry) and Hippophae Rhamnoides (sea buckthorn) extract, is protective in a model of type II DN. Diabetic db/db mice were administered DIAVIT in their drinking water for 14 weeks. We assessed the functional, structural, and ultra-structural phenotype of three experimental groups (lean+vehicle, db/db+vehicle, db/db+DIAVIT). We also investigated the angiogenic and fibrotic pathways involved in the mechanism of action of DIAVIT. Diabetic db/db mice developed hyperglycaemia, albuminuria, and an increased glomerular water permeability; the latter two were prevented by DIAVIT. db/db mice developed fibrotic glomeruli, endothelial insult, and glomerular ultra-structural changes, which were not present in DIAVIT-treated mice. Vascular endothelial growth factor A (VEGF-A) splicing was altered in the db/db kidney cortex, increasing the pro-angiogenic VEGF-A₁₆₅ relative to the anti-angiogenic VEGF-A₁₆₅b. This was partially prevented with DIAVIT treatment. Delphinidin, an anthocyanin abundant in DIAVIT, increased the VEGF-A₁₆₅b expression relative to total VEGF-A₁₆₅ in cultured podocytes through phosphorylation of the splice factor SRSF6. DIAVIT, in particular delphinidin, alters VEGF-A splicing in type II DN, rescuing the DN phenotype. This study highlights the therapeutic potential of natural drugs in DN through the manipulation of gene splicing and expression.

Vascular Oxidative Stress: Impact and Therapeutic Approaches

Oxidative stress has been defined as an imbalance between oxidants and antioxidants and more recently as a disruption of redox signaling and control. It is generally accepted that oxidative stress can lead to cell and tissue injury having a fundamental role in vascular dysfunction. Physiologically, reactive oxygen species (ROS) control vascular function by modulating various redox-sensitive signaling pathways. In vascular disorders, oxidative stress instigates endothelial dysfunction and inflammation, affecting several cells in the vascular wall. Vascular ROS are derived from multiple sources herein discussed, which are prime targets for therapeutic development. This review focuses on oxidative stress in vascular physiopathology and highlights different strategies to inhibit ROS production.

Renal outcomes with sodium glucose cotransporter 2 (SGLT2) inhibitor, dapagliflozin, in obese insulin-resistant model

A growing body of evidence indicates that obesity and insulin resistance contribute to the progression of renal disease. This study was performed to determine the effects of dapagliflozin, a novel sodium glucose cotransporter 2 (SGLT2) inhibitor, on renal and renal organic anion transporter 3 (Oat3) functions in high-fat diet fed rats, a model of obese insulin-resistance. Twenty-four male Wistar rats were divided into two groups, and received either a normal diet (ND) (n = 6) or a high-fat diet (HFD) (n = 18) for 16 weeks. At week 17, the HFD-fed rats were subdivided into three subgroups (n = 6/subgroup) and received either a vehicle (HFD), dapagliflozin (HFDAP; 1.0 mg/kg/day) or metformin (HFMET; 30 mg/kg/day), by oral gavage for four weeks. Metabolic parameters, renal function, renal Oat3 function, renal oxidative stress, and renal morphology were determined. The results showed that obese insulin-resistant rats induced by HFD feeding had impaired renal function and renal Oat3 function together with increased renal oxidative injury. Dapagliflozin or metformin treatment decreased insulin resistance, hypercholesterolemia, creatinine clearance and renal oxidative stress leading to improved renal function. However, dapagliflozin treatment decreased blood pressure, serum creatinine, urinary microalbumin and increased glucose excretions, and showed a greater ability to ameliorate impaired renal insulin signaling and glomerular barrier damage than metformin. These data suggest that dapagliflozin had greater efficacy than metformin for attenuating renal dysfunction and improving renal Oat3 function, at least in part by reducing renal oxidative stress and modulating renal insulin signaling pathways, and hence ameliorating renal injury.

Dysregulation of the Renin-Angiotensin System and the Vasopressinergic System Interactions in Cardiovascular Disorders

Purpose of Review

In many instances, the renin-angiotensin system (RAS) and the vasopressinergic system (VPS) are jointly activated by the same stimuli and engaged in the regulation of the same processes.

Recent Findings

Angiotensin II (Ang II) and arginine vasopressin (AVP), which are the main active compounds of the RAS and the VPS, interact at several levels. Firstly, Ang II, acting on AT1 receptors (AT1R), plays a significant role in the release of AVP from vasopressinergic neurons and AVP, stimulating V1a receptors (V1aR), regulates the release of renin in the kidney. Secondly, Ang II and AVP, acting on AT1R and V1aR, respectively, exert vasoconstriction, increase cardiac contractility, stimulate the sympathoadrenal system, and elevate blood pressure. At the same time, they act antagonistically in the regulation of blood pressure by baroreflex. Thirdly, the cooperative action of Ang II acting on AT1R and AVP stimulating both V1aR and V2 receptors in the kidney is necessary for the appropriate regulation of renal blood flow and the efficient resorption of sodium and water. Furthermore, both peptides enhance the release of aldosterone and potentiate its action in the renal tubules.

Summary

In this review, we (1) point attention to the role of the cooperative action of Ang II and AVP for the regulation of blood pressure and the water-electrolyte balance under physiological conditions, (2) present the subcellular mechanisms underlying interactions of these two peptides, and (3) provide evidence that dysregulation of the cooperative action of Ang II and AVP significantly contributes to the development of disturbances in the regulation of blood pressure and the water-electrolyte balance in cardiovascular diseases.

Hypertension regulating angiotensin peptides in the pathobiology of cardiovascular disease

Renin angiotensin system (RAS) is an endogenous hormone system involved in the control of blood pressure and fluid volume. Dysregulation of RAS has a pathological role in causing cardiovascular diseases through hypertension. Among several key components of RAS, angiotensin peptides, varying in amino acid length and biological function, have important roles in preventing or promoting hypertension, cardiovascular diseases, stroke, vascular remodeling etc. These peptides are generated by the metabolism of inactive angiotensinogen or its derived peptides by hydrolyzing action of certain enzymes. Angiotensin II, angiotensin (1-12), angiotensin A and angiotensin III bind primarily to angiotensin II type 1 receptor and cause vasoconstriction, accumulation of inflammatory markers to sub-endothelial region of blood vessels and activate smooth muscle cell proliferation. Moreover, when bound to angiotensin II type 2 receptor, angiotensin II works as cardio-protective peptide and halt pathological cell signals. Other peptides like angiotensin (1-9), angiotensin (1-7), alamandine and angiotensin IV also help in protecting from cardiovascular diseases by binding to their respective receptors.

A1166C polymorphism of the angiotensin II type 1 receptor gene contributes to hypertension susceptibility: evidence from a meta-analysis

Background The angiotensin II type 1 receptor (AT1R) gene is a prime candidate for polymorphisms that could contribute to hypertension. A polymorphism in the 3' untranslated region, leading to the transversion of adenine to cytosine at position 1166, has been the most-studied variant. However, the results have been inconsistent, and we therefore performed a meta-analysis to evaluate the association of this polymorphism with hypertension. Methods We conducted an extended a computer-based literature search of PubMed and Web of Knowledge up to November 30, 2015. The extracted data were analysed statistically, and pooled odds ratios with 95% confidence intervals were calculated to assess the strengths of associations using Review Manager software (version 5.2). Results After removing 5 studies that were not consistent with the Hardy-Weinberg equilibrium, we finally collected 41 case-control studies involving 11,837 cases and 11,020 controls to evaluate the association between AT1R polymorphisms and hypertension. We found that the risk of hypertension was higher for allele C than for allele A under the codominant model, significantly higher for genotype CC + AC than for genotype AA under the dominant model, and significantly higher for genotype CC + AC in Caucasians. Conclusion This meta-analysis suggests that the AT1R 1166 CC + AC genotype consistently confers susceptibility to hypertension and that early preventive measures should be applied in clinical settings according to patient genotypes.

Dietary nitrate improves age-related hypertension and metabolic abnormalities in rats via modulation of angiotensin II receptor signaling and inhibition of superoxide generation

Advanced age is associated with increased risk for cardiovascular disease and type 2 diabetes. A proposed central event is diminished amounts of nitric oxide (NO) due to reduced generation by endothelial NO synthase (eNOS) and increased oxidative stress. In addition, it is widely accepted that increased angiotensin II (ANG II) signaling is also implicated in the pathogenesis of endothelial dysfunction and hypertension by accelerating formation of reactive oxygen species. This study was designed to test the hypothesis that dietary nitrate supplementation could reduce blood pressure and improve glucose tolerance in aged rats, via attenuation of NADPH oxidase activity and ANG II receptor signaling. Dietary nitrate supplementation for two weeks reduced blood pressure (10-15mmHg) and improved glucose clearance in old, but not in young rats. These favorable effects were associated with increased insulin responses, reduced plasma creatinine as well as improved endothelial relaxation to acetylcholine and attenuated contractility to ANG II in resistance arteries. Mechanistically, nitrate reduced NADPH oxidase-mediated oxidative stress in the cardiovascular system and increased cGMP signaling. Finally, nitrate treatment in aged rats normalized the gene expression profile of ANG II receptors (AT_1A, AT₂, AT_1A/AT₂ ratio) in the renal and cardiovascular systems without altering plasma levels of renin or ANG II. Our results show that boosting the nitrate-nitrite-NO pathway can partly compensate for age-related disturbances in endogenous NO generation via inhibition of NADPH oxidase and modulation of ANG II receptor expression. These novel findings may have implications for nutrition-based preventive and therapeutic strategies against cardiovascular and metabolic diseases.

Molecular mechanisms in H2O2-induced increase in AT1 receptor gene expression in cardiac fibroblasts: A role for endogenously generated Angiotensin II

The AT1 receptor (AT1R) mediates the manifold actions of angiotensin II in the cardiovascular system. This study probed the molecular mechanisms that link altered redox status to AT1R expression in cardiac fibroblasts. Real-time PCR and western blot analysis showed that H2O2 enhances AT1R mRNA and protein expression via NADPH oxidase-dependent reactive oxygen species induction. Activation of NF-κB and AP-1, demonstrated by electrophoretic mobility shift assay, abolition of AT1R expression by their inhibitors, Bay-11-7085 and SR11302, respectively, and luciferase and chromatin immunoprecipitation assays confirmed transcriptional control of AT1R by NF-κB and AP-1 in H2O2-treated cells. Further, inhibition of ERK1/2, p38 MAPK and c-Jun N-terminal kinase (JNK) using chemical inhibitors or by RNA interference attenuated AT1R expression. Inhibition of the MAPKs showed that while ERK1/2 and p38 MAPK suffice for NF-κB activation, all three kinases are required for AP-1 activation. H2O2 also increased collagen type I mRNA and protein expression. Interestingly, the AT1R antagonist, candesartan, attenuated H2O2-stimulated AT1R and collagen mRNA and protein expression, suggesting that H2O2 up-regulates AT1R and collagen expression via local Angiotensin II generation, which was confirmed by real-time PCR and ELISA. To conclude, oxidative stress enhances AT1R gene expression in cardiac fibroblasts by a complex mechanism involving the redox-sensitive transcription factors NF-κB and AP-1 that are activated by the co-ordinated action of ERK1/2, p38 MAPK and JNK. Importantly, by causally linking oxidative stress to Angiotensin II and AT1R up-regulation in cardiac fibroblasts, this study offers a novel perspective on the pathogenesis of cardiovascular diseases associated with oxidative stress.

Intracellular angiotensin II as a regulator of muscle tone in vascular resistance vessels. Pathophysiological implications

The influence of intracellular angiotensin II on the regulation of potassium current and membrane potential of smooth muscle cells of mesenteric arteries and its relevance for the regulation of vascular tone was reviewed. The presence of components of the renin angiotensin system (RAS) in different cells of the cardiovascular system, was discussed including their presence in the nuclei and mitochondria. Emphasis was given to the opposite effects of intracellular and extracellular angiotensin II (Ang II) on the regulation of potassium current, membrane potential and contractility of vascular resistance vessels and its implication to vascular physiology and pathology and the possible role of epigenetic factors on the expression of angiotensin II (Ang II) and renin in vascular resistance vessels as well as its possible pathophysiological role in hypertension and other cardiovascular diseases.

Thymoquinone Ameliorates Cadmium-Induced Nephrotoxicity, Apoptosis, and Oxidative Stress in Rats is Based on its Anti-Apoptotic and Anti-Oxidant Properties

Cadmium (Cd), an environmental and industrial pollutant, generates free radicals responsible for oxidative stress. Cd can also lead to various renal toxic damage such as the proximal tubules and glomerulus dysfunction. Thymoquinone (TQ) is the main constituent of the essential oil obtained from black seeds (Nigella sativa) and has various pharmacological effects. The aim of the present study was to examine the nephroprotective, anti-oxidant, and anti-apoptotic effect of the TQ against Cd-induced nephrotoxicity. A total of 24 male Wistar albino rats were divided into three groups: control, Cd-treated, and Cd-treated with TQ; each group contain eight animals. The Cd-treated group was injected subcutaneously with CdCl2 dissolved in saline in the amount of 2 ml/kg/day for 30 days, resulting in a dosage of 1 mg/kg Cd. The rats in TQ-treated groups were given TQ (50 mg/kg body weight) once a day orally together with first Cd injection during the study period. The histopathological studies in the kidney of rats also showed that TQ markedly reduced the toxicity of Cd and preserved the normal histological architecture of the renal tissue. Immunohistochemical analysis revealed that TQ significantly decreased the Cd-induced over expression of nuclear factor-κB in renal tissue. Furthermore, TQ treatment resulted in decreased the number of apoptotic cells. TQ significantly suppressed lipid peroxidation, compensated deficits in the anti-oxidant defenses (reduced superoxide dismutase, glutathione peroxidase and catalase activities) in renal tissue resulted from Cd administration. These findings suggest that the nephroprotective potential of TQ in Cd toxicity might be due to its anti-oxidant and anti-apoptotic properties, which could be useful for achieving optimum effects in Cd-induced nephrotoxicity.

Synergistic Antihypertensive Effect of Carthamus tinctorius L. Extract and Captopril in L-NAME-Induced Hypertensive Rats via Restoration of eNOS and AT₁R Expression

This study examined the effect of Carthamus tinctorius (CT) extract plus captopril treatment on blood pressure, vascular function, nitric oxide (NO) bioavailability, oxidative stress and renin-angiotensin system (RAS) in N^ω-Nitro-l-arginine methyl ester (l-NAME)-induced hypertension. Rats were treated with l-NAME (40 mg/kg/day) for five weeks and given CT extract (75 or 150 or 300 or 500 mg/kg/day): captopril (5 mg/kg/day) or CT extract (300 mg/kg/day) plus captopril (5 mg/kg/day) for two consecutive weeks. CT extract reduced blood pressure dose-dependently, and the most effective dose was 300 mg/kg/day. l-NAME-induced hypertensive rats showed abnormalities including high blood pressure, high vascular resistance, impairment of acetylcholine-induced vasorelaxation in isolated aortic rings and mesenteric vascular beds, increased vascular superoxide production and plasma malondialdehyde levels, downregulation of eNOS, low level of plasma nitric oxide metabolites, upregulation of angiotensin II type 1 receptor and increased plasma angiotensin II. These abnormalities were alleviated by treatment with either CT extract or captopril. Combination treatment of CT extract and captopril normalized all the abnormalities found in hypertensive rats except endothelial dysfunction. These data indicate that there are synergistic antihypertensive effects of CT extract and captopril. These effects are likely mediated by their anti-oxidative properties and their inhibition of RAS.

Anti-hypertensive Herbs and their Mechanisms of Action: Part I

The use of herbal therapies for treatment and management of cardiovascular diseases (CVDs) is increasing. Plants contain a bounty of phytochemicals that have proven to be protective by reducing the risk of various ailments and diseases. Indeed, accumulating literature provides the scientific evidence and hence reason d'etre for the application of herbal therapy in relation to CVDs. Slowly, but absolutely, herbal remedies are being entrenched into evidence-based medical practice. This is partly due to the supporting clinical trials and epidemiological studies. The rationale for this expanding interest and use of plant based treatments being that a significant proportion of hypertensive patients do not respond to Modern therapeutic medication. Other elements to this equation are the cost of medication, side-effects, accessibility, and availability of drugs. Therefore, we believe it is pertinent to review the literature on the beneficial effects of herbs and their isolated compounds as medication for treatment of hypertension, a prevalent risk factor for CVDs. Our search utilized the PubMed and ScienceDirect databases, and the criterion for inclusion was based on the following keywords and phrases: hypertension, high blood pressure, herbal medicine, complementary and alternative medicine (CAM), nitric oxide, vascular smooth muscle cell (VSMC) proliferation, hydrogen sulfide, nuclear factor kappa-B, oxidative stress, and epigenetics/epigenomics. Each of the aforementioned keywords was co-joined with herb in question, and where possible with its constituent molecule(s). In this first of a two-part review, we provide a brief introduction of hypertension, followed by a discussion of the molecular and cellular mechanisms. We then present and discuss the plants that are most commonly used in the treatment and management of hypertension.

Endoplasmic reticulum stress increases AT1R mRNA expression via TIA-1-dependent mechanism

As the formation of ribonucleoprotein complexes is a major mechanism of angiotensin II type 1 receptor (AT1R) regulation, we sought to identify novel AT1R mRNA binding proteins. By affinity purification and mass spectroscopy, we identified TIA-1. This interaction was confirmed by colocalization of AT1R mRNA and TIA-1 by FISH and immunofluorescence microscopy. In immunoprecipitates of endogenous TIA- 1, reverse transcription-PCR amplified AT1R mRNA. TIA-1 has two binding sites within AT1R 3'-UTR. The binding site proximal to the coding region is glyceraldehyde-3-phosphate dehydrogenase (GAPDH)-dependent whereas the distal binding site is not. TIA-1 functions as a part of endoplasmic reticulum (ER) stress response leading to stress granule (SG) formation and translational silencing. We and others have shown that AT1R expression is increased by ER stress-inducing factors. In unstressed cells, TIA-1 binds to AT1R mRNA and decreases AT1R protein expression. Fluorescence microscopy shows that ER stress induced by thapsigargin leads to the transfer of TIA-1 to SGs. In FISH analysis AT1R mRNA remains in the cytoplasm and no longer colocalizes with TIA-1. Thus, release of TIA-1-mediated suppression by ER stress increases AT1R protein expression. In conclusion, AT1R mRNA is regulated by TIA-1 in a ER stress-dependent manner.

Angiotensin-(1-7) counteracts the effects of Ang II on vascular smooth muscle cells, vascular remodeling and hemorrhagic stroke: Role of the NFкB inflammatory pathway

Angiotensin (Ang)-(1-7) is a potential vasoprotective peptide. In the present study, we investigated its counteractive effects to Ang II on vascular smooth muscle cells (VSMCs) and intracerebral hemorrhagic stroke (ICH) through inflammatory mechanism. In in vitro experiments, human brain VSMCs (HBVSMCs) were treated with vehicle, Ang II, Ang II+Ang-(1-7), Ang II+A-779 or Ang II+Ang-(1-7)+A-779 (Mas receptor antagonist). HBVSMC proliferation, migration and apoptosis were determined by methyl thiazolyltetrazolium, wound healing assay and flow cytometry, respectively. In in vivo experiments, C57BL/6 mice were divided into vehicle, Ang II, Ang II+Ang-(1-7), Ang II+A-779 or Ang II+Ang-(1-7)+A-779 groups before they were subjected to collagenase-induced ICH or sham surgery. Hemorrhage volume and middle cerebral artery (MCA) remodeling were determined by histological analyses. Levels of NFκB, inhibitor of κBα (IκBα), tumor necrosis factor-α (TNF-α), monocyte chemoattractant protein 1 (MCP-1) and interleukin (IL-8) were measured by western blot or ELISA. We found that 1) Ang II increased HBVSMC migration, proliferation and apoptosis, and increased the blood pressure (BP), neurological deficit score, MCA remodeling and hemorrhage volume in ICH mice. 2) Ang-(1-7) counteracted these effects of Ang II, which was independent of BP, with the down-regulation of NFκB, up-regulation of IκBα, and decreased levels of TNF-α, MCP-1 and IL-8. 3) The beneficial effects of Ang-(1-7) could be abolished by A-779. In conclusion, Ang-(1-7) counteracts the effects of Ang II on ICH via modulating NFκB inflammation pathway in HBVSMCs and cerebral microvessels.

Chronic NF-κB blockade improves renal angiotensin II type 1 receptor functions and reduces blood pressure in Zucker diabetic rats

Background

Both angiotensin II type 1 receptor (AT₁R) and nuclear factor-kappa B (NF-κB) play significant roles in the pathogenesis of hypertension and type 2 diabetes. However, the role of NF-κB in perpetuating renal AT₁ receptors dysfunction remains unclear. The aim of the present study to determine whether blockade of NF-κB, could reverse the exaggerated renal AT₁R function, reduce inflammatory state and oxidative stress, lower blood pressure in Zucker diabetic fatty (ZDF) rats.

Methods

Pyrrolidine dithiocarbamate (PDTC), a NF-κB inhibitor (150 mg/kg in drinking water)or vehicle was administered orally to 12-weeks-old ZDF rats and their respective control lean Zucker (LZ) rats for 4 weeks. Blood pressure was measured weekly by tail-cuff method. AT₁R functions were determined by measuring diuretic and natriuretic responses to AT₁R antagonist (candesartan; 10 μg/kg/min iv). The mRNA and protein levels of NF-κB, oxidative stress maker and AT₁R were determined using quantitative real-time PCR and Western blotting, respectively. The NF-κB-DNA binding activity in renal cortex was measured by Electrophoretic mobility shift assay (EMSA).

Results

As compared with LZ rats, ZDF rats had higher blood pressure, impaired natriuresis and diuresis, accompanied with higher levels of oxidative stress and inflammation. Furthermore, AT₁R expression was higher in renal cortex from ZDF rats; candesartan induced natriresis and diuresis, which was augmented in ZDF rats. Treatment with PDTC lowered blood pressure and improved diuretic and natriuretic effects in ZDF rats; meanwhile, the increased oxidative stress and inflammation were reduced; the increased AT₁R expression and augmented candesartan-mediated natriuresis and diuresis were recoverd in ZDF rats. Our further study investigated the mechanisms of PDTC on AT₁R receptor expression. It resulted that PDTC inhibited NF-κB translocation from cytosol to nucleus, inhibited binding of NF-κB with AT₁R promoter, therefore, reduced AT₁R expression and function.

Conclusions

Our present study indicates blockade of NF-κB, via inhibition of binding of NF-κB with AT₁R promoter, reduces renal AT₁R expression and function, improves oxidative stress and inflammatory/anti-inflammatory balance, therefore, lowers blood pressure and recovers renal function in ZDF rats.

Electronic supplementary material

The online version of this article (doi:10.1186/s12933-015-0239-7) contains supplementary material, which is available to authorized users.

The protective effect of lipoic acid on selected cardiovascular diseases caused by age-related oxidative stress

Oxidative stress is considered to be the primary cause of many cardiovascular diseases, including endothelial dysfunction in atherosclerosis and ischemic heart disease, hypertension, and heart failure. Oxidative stress increases during the aging process, resulting in either increased reactive oxygen species (ROS) production or decreased antioxidant defense. The increase in the incidence of cardiovascular disease is directly related to age. Aging is also associated with oxidative stress, which in turn leads to accelerated cellular senescence and organ dysfunction. Antioxidants may help lower the incidence of some pathologies of cardiovascular diseases and have antiaging properties. Lipoic acid (LA) is a natural antioxidant which is believed to have a beneficial effect on oxidative stress parameters in relation to diseases of the cardiovascular system.

Beneficial effects of ethanol extracts of Red Liriope platyphylla on vascular dysfunction in the aorta of spontaneously hypertensive rats

Some biological effects of Red Liriope platyphylla (RLP) on various chronic diseases including Alzheimer's disease, diabetes and obesity were suggested after a report of the production from Liriope platyphylla (L. platyphylla, LP) roots using a steaming process. To examine the beneficial effects of ethanol extracts RLP (EEtRLP) on the vascular dysfunction of hypertension, alterations in key factors related to vascular regulation and antioxidant conditions were investigated in spontaneously hypertensive rats (SHR) after EEtRLP treatment for 2 weeks. High levels of 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity were detected in 500 or 1,000 mg/mL EEtRLP. Although no significant improvement of systolic blood pressure or aortic wall thickness were observed in the EEtRLP treated group, the expression level of angiotensin converting enzyme (ACE) and ACE2 increased significantly after EEtRLP treatment. Moreover, the concentration of aldosterone and K ion in serum rapidly recovered in the EEtRLP treated group relative to the vehicle treated group. Furthermore, the endothelial nitric oxide synthase (eNOS) expression and superoxide dismutase (SOD) activity were significantly increased in the EEtRLP treated group relative to the vehicle treated group, while the level of malondialdehyde (MDA) and NOx in the serum of the same group were recovered to the level of Wistar Kyoto (WKY) rats. Overall, the results presented herein provide novel evidence that EEtRLP treatment may improve vascular dysfunction in the aorta of the SHR through up regulation of the antioxidant state and down regulation of aldosterone and K ion concentration. These results also suggest that EEtRLP may be a potential candidate for treatment of various chronic diseases showing vascular dysfunction.