Which comes first: Renal inflammation or oxidative stress in spontaneously hypertensive rats?

Recent advancements in targeting the immune system to treat hypertension

Hypertension is the key leading risk factor for death globally, affecting ∼1.3 billion adults, particularly in low- and middle-income countries. Most people living with hypertension have uncontrolled high blood pressure, increasing their likelihood of cardiovascular events. Significant issues preventing blood pressure control include lack of diagnosis, treatment, and response to existing therapy. For example, monotherapy and combination therapy are often unable to lower blood pressure to target levels. New therapies are urgently required to tackle this issue, particularly those that target the mechanisms behind hypertension instead of treating its symptoms. Acting via an increase in systemic and tissue-specific inflammation, the immune system is a critical contributor to blood pressure regulation and is considered an early mechanism leading to hypertension development. Here, we review the immune system's role in hypertension, evaluate clinical trials that target inflammation, and discuss knowledge gaps in pre-clinical and clinical data. We examine the effects of anti-inflammatory drugs colchicine and methotrexate on hypertension and evaluate the blockade of pro-inflammatory cytokines IL-1β and TNF-α on blood pressure in clinical trials. Lastly, we highlight how we can move forward to target specific components of the immune system to lower blood pressure. This includes targeting isolevuglandins, which accumulate in dendritic cells to promote T cell activation and cytokine production in salt-induced hypertension. We discuss the potential of the dietary fibre-derived metabolites short-chain fatty acids, which have anti-inflammatory and blood pressure-lowering effects via the gut microbiome. This would limit adverse events, leading to improved medication adherence and better blood pressure control.

Intrinsically bioactive multifunctional Poly(citrate-curcumin) for rapid lung injury and MRSA infection therapy

Dysregulated inflammation after trauma or infection could result in the further disease and delayed tissue reconstruction. The conventional anti-inflammatory drug treatment suffers to the poor bioavailability and side effects. Herein, we developed an amphiphilic multifunctional poly (citrate-polyglycol-curcumin) (PCGC) nano oligomer with the robust anti-inflammatory activity for treating acute lung injury (ALI) and Methicillin-resistant staphylococcus aureus (MRSA) infected wound. PCGC demonstrated the sustained curcumin release, inherent photoluminescence, good cellular compatibility, hemocompatibility, robust antioxidant activity and enhanced cellular uptake. PCGC could efficiently scavenge nitrogen-based free radicals, oxygen-based free radicals, and intracellular oxygen species, enhance the endothelial cell migration and reduce the expression of pro-inflammatory factors through the NF-κB signal pathway. Combined the anti-inflammation and antioxidant properties, PCGC can shortened the inflammatory process. In animal model of ALI, PCGC was able to reduce the pulmonary edema, bronchial cell infiltration, and lung inflammation, while exhibiting rapid metabolic behavior in vivo. The MRSA-infection wound model showed that PCGC significantly reduced the expression of pro-inflammatory factors, promoted the angiogenesis and accelerated the wound healing. The transcriptome sequencing and molecular mechanism studies further demonstrated that PCGC could inhibit multiple inflammatory related pathways including TNFAIP3, IL-15RA, NF-κB. This work demonstrates that PCGC is efficient in resolving inflammation and promotes the prospect of application in inflammatory diseases as the drug-loaded therapeutic system.

Periodontitis accelerates the onset of hypertension in spontaneously hypertensive rats, while the electrical activation of the carotid sinus nerve delays the beginning of the increase in blood pressure

BACKGROUND

We have previously demonstrated that electrical stimulation of the carotid sinus nerve (CSN) protects the development of periodontitis. In the current study, we evaluated whether periodontitis accelerates the onset of hypertension in spontaneously hypertensive rats (SHR); and whether electrical stimulation of the CSN would delay the onset of hypertension.

METHODS

Three-week old SHR were implanted with electrodes around the CSN for electrical stimulation for 13 days. Bilateral ligation of the first molar and oral administration of Porphyromonas gingivalis induced periodontitis. The femoral artery of the SHR was cannulated, and 24 h later, in a conscious state, the blood pressure was recorded.

RESULTS

Five-week old sham SHR (subjects without electrical stimulation of the CSN) did not demonstrate hypertension. However, when the SHR were submitted to periodontitis they exhibited hypertension at 5 weeks of age. Nevertheless, the stimulation of the CSN prevented the onset of hypertension. Periodontitis promoted alveolar bone loss in SHR; but, electrical stimulation of the CSN prevented this undesirable outcome following the exposure to periodontitis.

CONCLUSION

Periodontitis accelerated the onset of hypertension in SHR; while the electrical stimulation of the CSN delayed the onset of hypertension.

Aerobic training increases renal antioxidant defence and reduces angiotensin II levels, mitigating the high mortality in SHR-STZ model

OBJECTVE

The purpose of the research was to investigate the effects of aerobic training on renal function, oxidative stress, intrarenal renin-angiotensin system, and mortality of hypertensive and diabetic (SHR-STZ) rats.

MATERIALS AND METHODS

Blood pressure, creatinine, urea levels, urinary glucose, urine volume, and protein excretion were reduced in trained SHR-STZ rats.

RESULTS

Aerobic training not only attenuated oxidative stress but also elevated the activity of antioxidant enzymes in the kid'ney of SHR-STZ rats. Training increased intrarenal levels of angiotensin-converting enzymes (ACE and ACE2) as well as the neprilysin (NEP) activity, along with decreased intrarenal angiotensin II (Ang II) levels. Aerobic training significantly improved the survival of STZ-SHR rats.

CONCLUSION

The protective role of aerobic training was associated with improvements in the renal antioxidative capacity, reduced urinary protein excretion along with reduced intrarenal Ang II and increased NEP activity. These findings might reflect a better survival under the combined pathological conditions, hypertension, and diabetes.

The Anti-Inflammatory Action of Pulsed Radiofrequency-A Hypothesis and Potential Applications

In 2013, it was reported that pulsed radiofrequency (PRF) could be applied to obtain a systemic anti-inflammatory effect. Patients with chronic pain and patients with an inflammatory condition from other disciplines could potentially profit from this finding. At that time, intravenous application was used, but since then, it became clear that it could be applied transcutaneously as well. This procedure was named RedoxPRF. This can be used both for regional and for systemic application. Recently, the basic element of the mode of action has been clarified from the analysis of the effects of PRF on a standard model of muscle injury in rats. The objective of this paper is to present a hypothesis on the mode of action of RedoxPRF now that the basic mechanism has become known. Cell stress causes an increased production of free radicals, disturbing the redox equilibrium, causing oxidative stress (OS) either directly or secondarily by other types of stress. Eventually, OS causes inflammation and an increased sympathetic (nervous) system activity. In the acute form, this leads to immune paralysis; in the chronic form, to immune tolerance and chronic inflammation. It is hypothesized that RedoxPRF causes a reduction of free radicals by a recombination of radical pairs. For systemic application, the target cells are the intravascular immune cells that pass through an activated area as on an assembly line. Hypothesis conclusions: 1. RedoxPRF treatment works selectively on OS. It has the unique position of having a point of engagement at the most upstream level of the train of events. 2. RedoxPRF has the potential of being a useful tool in the treatment of inflammatory diseases and possibly of stage 4 cancer. 3. In the treatment of chronic pain, RedoxPRF is an entirely new method because it is different from ablation as well as from stimulation. We propose the term "functional restoration". 4. Controlled studies must be conducted to develop this promising new field in medicine further.

Antibacterial and anti-inflammatory efficacy of N-acetyl cysteine in endodontic treatment: a scoping review

BACKGROUND

This scoping review systematically summarized the available evidence about the efficacy of N-acetyl cysteine (NAC) as an intracanal antibacterial and/or anti-inflammatory.

METHODS

PubMed, Scopus, Web of Science, and Google scholar search engines/databases were searched up to February 2022 to retrieve relevant studies. The studies were evaluated for eligibility criteria, and identifying relevant studies.

RESULTS

Out of 193 studies, 15 fulfilled the inclusion criteria and were processed for data extraction. Thirteen in vitro studies assessed antibacterial/antibiofilm efficacy of NAC, and reported good and promising efficacy: NAC was found as efficacious as the comparators (chlorhexidine, sodium hypochlorite, calcium hydroxide), or even showed higher efficacy. Regarding the anti-inflammatory efficacy of NAC, one in vitro study found it equivalent to, while one clinical trial revealed it more efficacious than calcium hydroxide.

CONCLUSIONS

There is accumulating evidence on the anti-microbial and anti-inflammatory efficacy of NAC in context of endodontics. However, further clinical trials with robust methodology and objective and reliable clinical, biological and microbial outcomes are warranted to translate its use for clinical practice on humans.

Oxidative Stress Parameters as Biomarkers of Cardiovascular Disease towards the Development and Progression

Cardiovascular disease (CVD) remains the leading cause of death globally, with unhealthy lifestyles today greatly increasing the risk. Over the decades, scientific investigation has been carried out on reactive oxygen species (ROS) and their resultant oxidative stress based on their changes made on biological targets such as lipids, proteins, and DNA. Since the existing clinical studies with antioxidants failed to provide relevant findings on CVD prediction, the focus has shifted towards recognition of oxidised targets as biomarkers to predict prognosis and response to accurate treatment. The identification of redox markers could help clinicians in providing risk stratification for CVD events beyond the traditional prognostic and diagnostic targets. This review will focus on how oxidant-related parameters can be applied as biomarkers for CVD based on recent clinical evidence.

DNA, protein and lipid oxidative damage in tissues of spontaneously hypertensive versus normotensive rats

Oxidative damage to protein and lipid macromolecules in target organs in hypertension has been recognized as a major factor contributing to cardiovascular, cerebrovascular, and renal diseases. Data on protein and lipid oxidative damage in spontaneously hypertensive rats are numerous, but there is no information on DNA damage in tissues measured by comet assay. The aim of this study was to determine the baseline damage to DNA, protein, and lipid macromolecules in different organs of spontaneously hypertensive rats. Markers of lipid peroxidation, protein oxidation, and DNA damage were measured in blood, heart, kidney, and liver of 24-week-old spontaneously hypertensive rats. Plasma prooxidant and antioxidant status were determined as well. Age-matched normotensive Wistar rats were used as control. A rise in markers of lipid peroxidation and protein oxidation, malondialdehyde, and advanced oxidation protein products, was detected in all tissues of spontaneously hypertensive rats, with particularly high values in the liver. DNA damage, measured by the comet assay, was significantly higher in all the studied tissues of spontaneously hypertensive rats compared to normotensive control, with more severe damage in the cardiac and renal cells. Significant depletion of the plasma antioxidant barrier in spontaneously hypertensive rats was also observed. This study showed increased damage to all macromolecules in all studied samples of spontaneously hypertensive rats in comparison with control Wistar rats.

Pharmacological Properties and Health Benefits of Eugenol: A Comprehensive Review

The biologically active phytochemicals are sourced from edible and medicinally important plants and are important molecules being used for the formulation of thousands of drugs. These phytochemicals have great benefits against many ailments particularly the inflammatory diseases or oxidative stress-mediated chronic diseases. Eugenol (EUG) is a versatile naturally occurring molecule as phenolic monoterpenoid and frequently found in essential oils in a wide range of plant species. EUG bears huge industrial applications particularly in pharmaceutics, dentistry, flavoring of foods, agriculture, and cosmeceutics. It is being focused recently due to its great potential in preventing several chronic conditions. The World Health Organization (WHO) has declared EUG as a nonmutant and generally recognized as safe (GRAS) molecule. The available literature about pharmacological activities of EUG shows remarkable anti-inflammatory, antioxidant, analgesic, and antimicrobial properties and has a significant effect on human health. The current manuscript summarizes the pharmacological characteristics of EUG and its potential health benefits.

Increased expression of acyl-CoA oxidase 2 in the kidney with plasma phytanic acid and altered gut microbiota in spontaneously hypertensive rats

We performed a DNA microarray analysis of the renal medulla and cortex from spontaneously hypertensive rats (SHRs), stroke-prone SHRs (SHRSPs), and Wistar-Kyoto (WKY) rats to identify pivotal molecules in the kidney associated with the onset of hypertension and found increased expression of acyl-CoA oxidase 2 (Acox2) mRNA. Real-time polymerase chain reaction revealed that Acox2 mRNA expression in the renal medulla and cortex of SHRs and SHRSPs was increased in comparison to WKY rats. These findings indicate that increased renal ACOX2 (an enzyme that induces the β-oxidation of fatty acids) is associated with the onset of hypertension. Immunostaining of ACOX2 in the distal tubules from SHRs was stronger than that in the distal tubules from WKY rats. Western blot analysis showed increased expression of ACOX2 protein in renal medulla from SHRs. Regarding the overexpression of ACOX2, plasma levels of phytanic acid in SHRs were significantly higher than those in WKY rats. There were no differences in other short-chain fatty acids. Plasma phytanic acid was affected by the gut microbiota through the conversion from phytol by yeast in the intestinal tract. We compared the gut microbiota profile in three strains of 5-week-old rats by the terminal-restriction fragment length polymorphism method. The gut microbiota profile and ratio of Firmicutes/Bacteroides differed between SHRs and WKY rats. These findings suggest that the increased expression of ACOX2 in the kidney along with increases in plasma phytanic acid and the altered gut microbiota may be involved in the oxidation in the kidney and the pathogenesis of hypertension.

Antioxidant, Anti-tyrosinase, Anti-α-amylase, and Cytotoxic Potentials of the Invasive Weed Andropogon virginicus

Andropogon virginicus is an invasive weed that seriously threatens agricultural production and economics worldwide. In this research, dried aerial parts of A. virginicus were extracted, applying Soxhlet and liquid-liquid phase methods to acquire the total crude (T-Anvi), hexane (H-Anvi), ethyl acetate (E-Anvi), butanol (B-Anvi), and water (W-Anvi) extracts, respectively. In which, T-Anvi contains the highest total phenolic and flavonoid contents (24.80 mg gallic acid and 37.40 mg rutin equivalents per g dry weight, respectively). Via anti-radical (ABTS and DPPH), and reducing power assays, E-Anvi exhibits the most potent activities (IC₅₀ = 13.96, 43.59 and 124.11 µg/mL, respectively), stronger than butylated hydroxytoluene (BHT), a standard antioxidant, while the lipid peroxidation inhibitory effect of E-Anvi (LPI = 90.85% at the concentration of 500 µg/mL) is close to BHT. E-Anvi shows the most substantial inhibition (IC₅₀ = 2.58 mg/mL) on tyrosinase. Notably, α-amylase is significantly suppressed by H-Anvi (IC₅₀ = 0.72 mg/mL), over twice stronger than the positive control, palmitic acid. In the cytotoxic assay, E-Anvi is the strongest extract inhibiting K562 cells (IC₅₀ = 112.01 µg/mL). Meanwhile, T-Anvi shows the highest prevention on Meg-01 expansion (IC₅₀ = 91.40 µg/mL). Dominant compounds detected in E-Anvi by high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry (HPLC-ESI-MS/MS) are identified as flavonoids. However, among four major compounds identified in H-Anvi by gas chromatography-mass spectrometry (GC-MS), palmitic acid and phytol are the most abundant compounds with peak areas of 27.97% and 16.42%, respectively. In essence, this is the first report describing that A. virginicus is a potential natural source of antioxidants, tyrosinase and α-amylase inhibitors, and anti-chronic myeloid leukemia (CML) agents which may be useful in future therapeutics as promising alternative medicines.

The superoxide scavenger tempol attenuates DNA oxidative injury and spontaneous pain-like behavior in chronic post-cast pain model rats

The mechanism of severe pain occurring because of physical disuse, such as complex regional pain syndrome Type I, has not been elucidated so far. Therefore, to investigate this mechanism, we have developed a model called a chronic post-cast pain (CPCP) model. Oxidative stress-related factors generated in a fixed limb may be triggers for nociceptive signals due to physical disuse. On the basis of the results of our previous studies, we speculated that oxidative stress-related factors in immobilized hind limbs may also be triggers of nociceptive signals due to physical disuse. In this study, we aimed to clarify whether an oxidative stress-related factor is involved in the induction of nociceptive signals. The time course of oxidative damage in the soleus (slow-twitch fiber) and gastrocnemius (fast-twitch fiber) muscles was evaluated by immunostaining of 8-hydroxy-2'-deoxyguanosine (a marker of oxidative damage in DNA). We also investigated the effects of tempol, a scavenger of superoxide, on oxidative damage in DNA, spontaneous pain-related behaviors (licking and/or biting and flinching), and the activation of spinal dorsal horn neurons (c-Fos). Systemic administration of tempol before cast removal attenuated oxidative damage to DNA in immobilized skeletal muscles, suppressed spontaneous pain-related behavior, and suppressed the activation of spinal dorsal horn neurons. We suggest that superoxide generated in immobilized skeletal muscles after cast removal is one of the peripheral factors that trigger nociceptive signals.

Hepatoprotective properties of red betel (Piper crocatum Ruiz and Pav) leaves extract towards H2O2-induced HepG2 cells via anti-inflammatory, antinecrotic, antioxidant potency

BACKGROUND

Prolonged exposure of free radicals, or known as reactive oxygen species (ROS), in hepatic cells may cause oxidative stress. Without proper treatment, it can induce liver injury and fatal hepatic disease, including cirrhosis. Red betel (Piper crocatum Ruiz and Pav) is one of Indonesia's medicinal plants that has been known to exhibit antioxidant, anti-inflammatory activities. This study aims to determine hepatoprotective effect of red betel leaves extract (RBLE) towards liver injury.

METHOD

Hydrogen peroxide-induced HepG2 cells were used as liver injury model·H2O2-induced HepG2 cells were treated with 25 µg/mL and 100 µg/mL RBLE. Several parameters were observed, including TNF-α level through ELISA; necrotic, apoptotic, dead, live cells; and ROS level through flow cytometry analysis; and GPX gene expression through qPCR.

RESULT

The study showed that treatment with RBLE were able to decrease TNF-α level; necrotic and death cells percentage; as well as ROS level. On the other hand, it were able to increase apoptotic and live cells percentage; as well as GPX gene expression. Low concentration (25 µg/mL) of RBLE treatment exhibited stronger anti-inflammatory activity as it was resulted in the lower TNF-α level and were able to switched hepatic cell death pathway from necrosis to apoptosis as shown by the shifted of apoptotic cells and necrotic cells percentage. This lead to lower death cells and ultimately improve live cells percentage. Meanwhile high concentration of RBLE (100 µg/mL) exhibited stronger antioxidant properties as indicated by lower ROS level and higher GPX gene expression.

CONCLUSION

Overall, this study was able to demonstrate hepatoprotective effect of RBLE towards liver injury model through its anti-inflammatory and antioxidant activities.

Hypoxia-mediated regulation of mitochondrial transcription factors in renal epithelial cells: implications for hypertensive renal physiology

Kidneys have a high resting metabolic rate and low partial pressure of oxygen due to enhanced mitochondrial oxygen consumption and ATP production needed for active solute transport. Heightened mitochondrial activity leads to progressively increasing hypoxia from the renal cortex to the renal medulla. Renal hypoxia is prominent in hypertensive rats due to increased sodium reabsorption within the nephrons, which demands higher energy production by oxidative phosphorylation (OXPHOS). Consequently, spontaneously hypertensive rats (SHR) display greater oxygen deficiency (hypoxia) than normotensive Wistar Kyoto rats (WKY). Here, we sought to investigate the expression of key proteins for mitochondrial biogenesis in SHR and WKY, and study the regulation of mitochondrial transcription factors (mtTFs) under in vitro hypoxic conditions in renal epithelial cells. We report that renal expressions of hypoxia-inducible factor-1-alpha (HIF-1α), peroxisome proliferator-activated receptor-gamma coactivator-1-alpha (PGC-1α), mtTFs, and OXPHOS proteins are elevated in SHR compared to WKY. In addition, our experiments in cultured kidney cells demonstrate that acute hypoxia augments the expression of these genes. Furthermore, we show that the transcripts of HIF-1α and mtTFs are positively correlated in various human tissues. We reveal, for the first time to our knowledge, that HIF-1α transactivates mtTF genes by direct interaction with their promoters in rat kidney epithelial cells (NRK-52E) under acute hypoxia. Concomitant increases in the mitochondrial DNA and RNA, and OXPHOS proteins are observed. Taken together, this study suggests that hypoxia within the renal epithelial cells may enhance mitochondrial function to meet the energy demand in proximal tubular cells during prehypertensive stages in kidneys of young SHR.

Inhibition of RAGE by FPS-ZM1 alleviates renal injury in spontaneously hypertensive rats

The current study was designed to examine the protection of RAGE-specific inhibitor FPS-ZM1 against renal injury in spontaneously hypertensive rats (SHR) and investigate the underlying mechanism. The adult male SHR were treated with FPS-ZM1 via oral gavages for 12 weeks, and age-matched male Wistar-Kyoto rats (WKY) were used as control. Treatment of SHR with FPS-ZM1 slightly reduced blood pressure, and significantly improved baroreflex sensitivity in SHR. Treatment of SHR with FPS-ZM1 improved renal function, evidenced by increased glomerular filtration rate and renal blood flow, and reduced plasma creatinine, blood urea nitrogen and urine albumin excretion rate. Histology results revealed that treatment of SHR with FPS-ZM1 alleviated renal injury and reduced tubulointerstitial fibrosis. Treatment of SHR with FPS-ZM1 suppressed activation of NF-κB and reduced expression of pro-inflammatory cytokines including Tnf, Il6, and Il1b. Treatment of SHR with FPS-ZM1 abated oxidative stress and downregulated mRNA levels of components of NADPH oxidase (Nox) including Cyba, Nox1, Nox2, Nox4 and Ncf1 in kidneys. In addition, treatment of SHR with FPS-ZM1 reduced renal AngII levels, downregulated mRNA expression of Ace and upregulated expression of Agtr2. In conclusion, treatment with FPS-ZM1 alleviated hypertension-related renal dysfunction, possibly by suppressing NF-κB-mediated inflammation, abating Nox-mediated oxidative stress, and improving local renal renin-angiotensin system (RAS).

Effect of Treatment with Peptide Extract from Beef Myofibrillar Protein on Oxidative Stress in the Brains of Spontaneously Hypertensive Rats

This study was conducted to determine the effect of beef peptide extract on oxidative stress in the brains of spontaneously hypertensive rats (SHRs). A 3-kDa peptide extract was obtained from beef myofibrillar protein using alkaline-AK (AK3K). Oxidative stress in SHR brains was measured by assessing malondialdehyde (MDA) and reactive oxygen species (ROS) concentrations and superoxide dismutase (SOD), catalase, and glutathione peroxidase (GPx) activity. The SHR brains treated with the AK3K peptide extract (400 mg/kg body weight, AK3K400) showed a significant decrease in MDA and ROS contents by 0.33 and 23.92 μM, respectively (p < 0.05) compared to the control. The SOD activity for AK3K400 was 61.26%, around 20% higher than the control. Furthermore, the SHRs treated with the AK3K peptide extract showed results similar to those obtained using captopril, a hypertension drug, except for the MDA level. The study demonstrates that the beef peptide extract inhibits the generation of oxidative stress in the SHR brain and could possibly be used for neuronal hypertension therapy.

Consumption of Chlorogenic Acids through Coffee and Health Implications

Chlorogenic acids (CGA) are the main antioxidant compounds in the Western diet, due to their high concentrations in coffee associated with the high consumption of the beverage. Until about 10 years ago, like many other phenolic compounds, CGA were thought to be poorly absorbed in the human digestive system. Along the years, large amounts of information on the absorption and metabolism of these compounds have been unveiled, and today, it is known that, on average, about one third of the consumed CGA from coffee is absorbed in the human gastrointestinal tract, although large inter-individual variation exists. Considering results from in vitro animal and human studies, it is possible to conclude that the antioxidant and anti-inflammatory effects of coffee CGA are responsible for, at least to a certain extent, the association between coffee consumption and lower incidence of various degenerative and non-degenerative diseases, in addition to higher longevity.

An Overview on the Anti-inflammatory Potential and Antioxidant Profile of Eugenol

The bioactive compounds found in foods and medicinal plants are attractive molecules for the development of new drugs with action against several diseases, such as those associated with inflammatory processes, which are commonly related to oxidative stress. Many of these compounds have an appreciable inhibitory effect on oxidative stress and inflammatory response, and may contribute in a preventive way to improve the quality of life through the use of a diet rich in these compounds. Eugenol is a natural compound that has several pharmacological activities, action on the redox status, and applications in the food and pharmaceutical industry. Considering the importance of this compound, the present review discusses its anti-inflammatory and antioxidant properties, demonstrating its mechanisms of action and therapeutic potential for the treatment of inflammatory diseases.

Bio-accessible milk casein derived tripeptide (LLY) mediates overlapping anti- inflammatory and anti-oxidative effects under cellular (Caco-2) and in vivo milieu

Inflammation and oxidative stress are closely linked patho-physiological processes which occur concurrently in many diseased conditions. Recently, interdependence between these two processes explains the antioxidant paradox associated with failure to select appropriate agents required for prevention of diseases known to be induced by oxidative stress. Present study established the overlapping anti-inflammatory and anti-oxidative potential along with bio-accessibility of milk casein derived tripeptide (LLY). Tripeptide exhibited anti-inflammatory response under ex vivo conditions by suppressing (P<.01) mice splenocytes proliferation and modulating their cytokines (IFN-γ, IL-10 and TGF-β) with improved phagocytosis of peritoneal macrophages. Conversely, tripeptide displayed extraordinary radical scavenging ability and cellular anti-oxidative potential using chemical assays and H₂O₂ induced oxidative stress model on Caco-2 cells. Under cellular assessment, on one hand tripeptide inhibited (P<.01) intracellular ROS generation and reduced MDA and protein carbonyls but on the other also increased (P<.01) the activity of anti-oxidative enzyme, catalase without much effect on SOD and GPx. This anti-oxidative potential was further established by studying relative expression of genes (Nrf-2 and Keap1) and Nrf-2 nuclear translocation associated with anti-oxidative signaling in Caco-2 cells. Bio-accessibility of tripeptide and its intact transport across Caco-2 cell monolayer was also found to be 1.72±0.22% through PepT1 mediated transport mechanism. Besides, tripeptide displayed strong anti-oxidative and anti-inflammatory potential under in vivo conditions in mice against ethanol induced oxidative stress by elevating (P<.01) liver GSH content and by decreasing (P<.01) the activities of anti-oxidative enzymes, MDA along with reduced expression of CYP2E1, PPAR-α, TNF-α and COX-2 genes than ethanol control.

Oxidative Stress in Patients with Drug Resistant Partial Complex Seizure

Oxidative stress (OS) has been implicated as a pathophysiological mechanism of drug-resistant epilepsy, but little is known about the relationship between OS markers and clinical parameters, such as the number of drugs, age onset of seizure and frequency of seizures per month. The current study’s aim was to evaluate several oxidative stress markers and antioxidants in 18 drug-resistant partial complex seizure (DRPCS) patients compared to a control group (age and sex matched), and the results were related to clinical variables. We examined malondialdehyde (MDA), advanced oxidation protein products (AOPP), advanced glycation end products (AGEs), nitric oxide (NO), uric acid, superoxide dismutase (SOD), glutathione, vitamin C, 4-hydroxy-2-nonenal (4-HNE) and nitrotyrosine (3-NT). All markers except 4-HNE and 3-NT were studied by spectrophotometry. The expressions of 4-HNE and 3-NT were evaluated by Western blot analysis. MDA levels in patients were significantly increased (p ≤ 0.0001) while AOPP levels were similar to the control group. AGEs, NO and uric acid concentrations were significantly decreased (p ≤ 0.004, p ≤ 0.005, p ≤ 0.0001, respectively). Expressions of 3-NT and 4-HNE were increased (p ≤ 0.005) similarly to SOD activity (p = 0.0001), whereas vitamin C was considerably diminished (p = 0.0001). Glutathione levels were similar to the control group. There was a positive correlation between NO and MDA with the number of drugs. The expression of 3-NT was positively related with the frequency of seizures per month. There was a negative relationship between MDA and age at onset of seizures, as well as vitamin C with seizure frequency/month. We detected an imbalance in the redox state in patients with DRCPS, supporting oxidative stress as a relevant mechanism in this pathology. Thus, it is apparent that some oxidant and antioxidant parameters are closely linked with clinical variables.

Diabetic nephropathy: Is there a role for oxidative stress?

Oxidative stress has been implicated in the pathophysiology of diabetic nephropathy. Studies in experimental animal models of diabetes strongly implicate oxidant species as a major determinant in the pathophysiology of diabetic kidney disease. The translation, in the clinical setting, of these concepts have been quite disappointing, and new theories have challenged the concepts that oxidative stress per se plays a role in the pathophysiology of diabetic kidney disease. The concept of mitochondrial hormesis has been introduced to explain this apparent disconnect. Hormesis is intended as any cellular process that exhibits a biphasic response to exposure to increasing amounts of a substance or condition: specifically, in diabetic kidney disease, oxidant species may represent, at determined concentration, an essential and potentially protective factor. It could be postulated that excessive production or inhibition of oxidant species formation might result in an adverse phenotype. This review discusses the evidence underlying these two apparent contradicting concepts, with the aim to propose and speculate on potential mechanisms underlying the role of oxidant species in the pathophysiology of diabetic nephropathy and possibly open future more efficient therapies to be tested in the clinical settings.

Oxidative Stress in Oral Diseases: Understanding Its Relation with Other Systemic Diseases

Oxidative stress occurs in diabetes, various cancers, liver diseases, stroke, rheumatoid arthritis, chronic inflammation, and other degenerative diseases related to the nervous system. The free radicals have deleterious effect on various organs of the body. This is due to lipid peroxidation and irreversible protein modification that leads to cellular apoptosis or programmed cell death. During recent years, there is a rise in the oral diseases related to oxidative stress. Oxidative stress in oral disease is related to other systemic diseases in the body such as periodontitis, cardiovascular, pancreatic, gastric, and liver diseases. In the present review, we discuss the various pathways that mediate oxidative cellular damage. Numerous pathways mediate oxidative cellular damage and these include caspase pathway, PERK/NRF2 pathway, NADPH oxidase 4 pathways and JNK/mitogen-activated protein (MAP) kinase pathway. We also discuss the role of inflammatory markers, lipid peroxidation, and role of oxygen species linked to oxidative stress. Knowledge of different pathways, role of inflammatory markers, and importance of low-density lipoprotein, fibrinogen, creatinine, nitric oxide, nitrates, and highly sensitive C-reactive proteins may be helpful in understanding the pathogenesis and plan better treatment for oral diseases which involve oxidative stress.

Oxidative imbalance and kidney damage in spontaneously hypertensive rats: activation of extrinsic apoptotic pathways

In both humans and animals, essential hypertension acts as a risk factor for subclinical kidney damage and precedes renal dysfunction. Several lines of evidence indicate that hypertension and oxidative stress are closely related. The increase in vascular oxidative stress plays a key role in the pathophysiological consequences of hypertension, including kidney disease. Our study examined this issue in spontaneously hypertensive rat (SHR), a reliable model of essential hypertension. We used SHR 20 weeks old when hypertension is stably developed, vascular remodeling started, but kidney function is preserved. We examined plasmatic pro-oxidant and antioxidant status showing a significant alteration in oxidative balance in SHR. As index of oxidative damage, we evaluated lipid peroxidation in kidney, liver, and skeletal muscle, detecting a significant rise in lipid peroxidation levels in all SHR tissues, particularly relevant in kidney. In addition, we analyzed the expression of cytoplasmic antioxidant enzymes, superoxide dismutase 1 (SOD1) and glutatione S-tranferasi P1 (GSTP1). In SHR liver, SOD1 expression slight increased while we have not detected any variation in other tissues. Concerning GSTP1, SHR renal tissues did not display variations in enzyme expression, while in the other tissues, we observed a significant increase in both monomeric and pro-apoptotic dimeric form of the enzyme. By analyzing apoptotic signal, we founded c-Jun N-terminal kinase (JNK) activation in all SHR tissues, but only kidney presented extrinsic apoptotic pathway activation. Our results suggest that, in hypertensive animals with preserved renal function, despite the remarkable oxidative damage of renal tissues, only the extrinsic apoptotic pathway is activated.

Anti-Inflammatory Activity of Citrus bergamia Derivatives: Where Do We Stand?

Inflammatory diseases affect a large portion of the worldwide population, and chronic inflammation is a major risk factor for several dangerous pathologies. To limit the side effects of both synthetic and biological anti-inflammatory drugs, the use of herbal medicines, nutraceuticals and food supplements has increased tremendously as alternative and/or complementary medicine to treat several pathologies, including inflammation. During the last decades, the biological properties of Citrus bergamia (bergamot) derivatives have obtained important scientific achievements, and it has been suggested their use in a context of a multitarget pharmacological strategy. Here, we present an overview of the anti-inflammatory properties of bergamot extracts that could represent the scientific basis for develop novel and alternative strategies to improve health status and attenuate inflammatory conditions.

Does the Interdependence between Oxidative Stress and Inflammation Explain the Antioxidant Paradox?

Oxidative stress has been implicated in many chronic diseases. However, antioxidant trials are so far largely unsuccessful as a preventive or curative measure. Chronic low-grade inflammatory process, on the other hand, plays a central role in the pathogenesis of a number of chronic diseases. Oxidative stress and inflammation are closely related pathophysiological processes, one of which can be easily induced by another. Thus, both processes are simultaneously found in many pathological conditions. Therefore, the failure of antioxidant trials might result from failure to select appropriate agents that specifically target both inflammation and oxidative stress or failure to use both antioxidants and anti-inflammatory agents simultaneously or use of nonselective agents that block some of the oxidative and/or inflammatory pathways but exaggerate the others. To examine whether the interdependence between oxidative stress and inflammation can explain the antioxidant paradox we discussed in the present review the basic aspects of oxidative stress and inflammation and their relationship and dependence.

Tongxinluo Protects against Hypertensive Kidney Injury in Spontaneously-Hypertensive Rats by Inhibiting Oxidative Stress and Activating Forkhead Box O1 Signaling

Hypertension is an independent risk factor for the progression of chronic renal failure, and oxidative stress plays a critical role in hypertensive renal damage. Forkbox O1(FoxO1) signaling protects cells against oxidative stress and may be a useful target for treating oxidative stress-induced hypertension. Tongxinluo is a traditional Chinese medicine with cardioprotective and renoprotective functions. Therefore, this study aimed to determine the effects of Tongxinluo in hypertensive renal damage in spontaneously hypertensive rats(SHRs)and elucidate the possible involvement of oxidative stress and FoxO1 signaling in its molecular mechanisms. SHRs treated with Tongxinluo for 12 weeks showed a reduction in systolic blood pressure. In addition to increasing creatinine clearance, Tongxinluo decreased urinary albumin excretion, oxidative stress injury markers including malondialdehyde and protein carbonyls, and expression of nicotinamide adenine dinucleotide phosphate oxidase subunits and its activity in SHR kidneys. While decreasing phosphorylation of FoxO1, Tongxinluo also inhibited the phosphorylation of extracellular signal-regulated kinase1/2 and p38 and enhanced manganese superoxide dismutase and catalase activities in SHR kidneys. Furthermore, histology revealed attenuation of glomerulosclerosis and renal podocyte injury, while Tongxinluo decreased the expression of α-smooth muscle actin, extracellular matrixprotein, transforming growth factor β1 and small mothers against decapentaplegic homolog 3,and improved tubulointerstitial fibrosis in SHR kidneys. Finally, Tongxinluo inhibited inflammatory cell infiltration as well as expression of tumor necrosis factor-α and interleukin-6. In conclusion, Tongxinluo protected SHRs against hypertension-induced renal injury by exerting antioxidant, antifibrotic, and anti-inflammatory activities. Moreover, the underlying mechanisms of these effects may involve inhibition of oxidative stress and functional activation of FoxO1 signaling.

Antioxidants in Cardiovascular Therapy: Panacea or False Hope?

Oxidative stress is a key feature of the atherothrombotic process involved in the etiology of heart attacks, ischemic strokes, and peripheral arterial disease. It stands to reason that antioxidants represent a credible therapeutic option to prevent disease progression and thereby improve outcome, but despite positive findings from in vitro studies, clinical trials have failed to consistently show benefit. The aim of this review is to re-appraise the concept of antioxidants in the prevention and management of cardiovascular disease. In particular, the review will explore the reasons behind failed antioxidant strategies with vitamin supplements and will evaluate how flavonoids might improve cardiovascular function despite bioavailability that is not sufficiently high to directly influence antioxidant capacity. As well as reaching conclusions relating to those antioxidant strategies that might hold merit, the major myths, limitations, and pitfalls associated with this research field are explored.

Renal autoregulation in health and disease

Intrarenal autoregulatory mechanisms maintain renal blood flow (RBF) and glomerular filtration rate (GFR) independent of renal perfusion pressure (RPP) over a defined range (80-180 mmHg). Such autoregulation is mediated largely by the myogenic and the macula densa-tubuloglomerular feedback (MD-TGF) responses that regulate preglomerular vasomotor tone primarily of the afferent arteriole. Differences in response times allow separation of these mechanisms in the time and frequency domains. Mechanotransduction initiating the myogenic response requires a sensing mechanism activated by stretch of vascular smooth muscle cells (VSMCs) and coupled to intracellular signaling pathways eliciting plasma membrane depolarization and a rise in cytosolic free calcium concentration ([Ca(2+)]i). Proposed mechanosensors include epithelial sodium channels (ENaC), integrins, and/or transient receptor potential (TRP) channels. Increased [Ca(2+)]i occurs predominantly by Ca(2+) influx through L-type voltage-operated Ca(2+) channels (VOCC). Increased [Ca(2+)]i activates inositol trisphosphate receptors (IP3R) and ryanodine receptors (RyR) to mobilize Ca(2+) from sarcoplasmic reticular stores. Myogenic vasoconstriction is sustained by increased Ca(2+) sensitivity, mediated by protein kinase C and Rho/Rho-kinase that favors a positive balance between myosin light-chain kinase and phosphatase. Increased RPP activates MD-TGF by transducing a signal of epithelial MD salt reabsorption to adjust afferent arteriolar vasoconstriction. A combination of vascular and tubular mechanisms, novel to the kidney, provides for high autoregulatory efficiency that maintains RBF and GFR, stabilizes sodium excretion, and buffers transmission of RPP to sensitive glomerular capillaries, thereby protecting against hypertensive barotrauma. A unique aspect of the myogenic response in the renal vasculature is modulation of its strength and speed by the MD-TGF and by a connecting tubule glomerular feedback (CT-GF) mechanism. Reactive oxygen species and nitric oxide are modulators of myogenic and MD-TGF mechanisms. Attenuated renal autoregulation contributes to renal damage in many, but not all, models of renal, diabetic, and hypertensive diseases. This review provides a summary of our current knowledge regarding underlying mechanisms enabling renal autoregulation in health and disease and methods used for its study.

Roles of inflammation, oxidative stress, and vascular dysfunction in hypertension

Hypertension is a complex condition and is the most common cardiovascular risk factor, contributing to widespread morbidity and mortality. Approximately 90% of hypertension cases are classified as essential hypertension, where the precise cause is unknown. Hypertension is associated with inflammation; however, whether inflammation is a cause or effect of hypertension is not well understood. The purpose of this review is to describe evidence from human and animal studies that inflammation leads to the development of hypertension, as well as the evidence for involvement of oxidative stress and endothelial dysfunction--both thought to be key steps in the development of hypertension. Other potential proinflammatory conditions that contribute to hypertension-such as activation of the sympathetic nervous system, aging, and elevated aldosterone--are also discussed. Finally, we consider the potential benefit of anti-inflammatory drugs and statins for antihypertensive therapy. The evidence reviewed suggests that inflammation can lead to the development of hypertension and that oxidative stress and endothelial dysfunction are involved in the inflammatory cascade. Aging and aldosterone may also both be involved in inflammation and hypertension. Hence, in the absence of serious side effects, anti-inflammatory drugs could potentially be used to treat hypertension in the future.

Female spontaneously hypertensive rats have a compensatory increase in renal regulatory T cells in response to elevations in blood pressure

Female spontaneously hypertensive rats (SHR) have more regulatory T cells (Tregs) in their kidneys than males. The goal of this study was to determine the impact of blood pressure (BP) on the renal immune profile. We hypothesize that increases in BP promote a proinflammatory renal T cell and cytokine profile in SHR, although females will have greater hormone-dependent increases in Tregs and males will have greater increases in Th17 cells. Renal T cell and cytokine profiles were assessed in male and female Wistar-Kyoto rats and male and female SHR treated with vehicle or hydrochlorothiazide and reserpine (HCTZ) from 6 to 12 (6-HCTZ) or 11 to 13 weeks of age (2-HCTZ). Regardless of sex, SHR had a more proinflammatory renal immune profile than Wistar-Kyoto rats. 6-HCTZ attenuated age-related increases in BP and 2-HCTZ reversed hypertension compared with vehicle-treated SHR. Neither 6-HCTZ nor 2-HCTZ altered CD3(+), CD4(+), or CD8(+) T cells in either sex. Both treatments decreased Tregs only in female SHR abolishing sex differences in Tregs. 6-HCTZ has no impact on Th17 cells in either sex and 2-HCTZ had a minimal impact on renal Th17 cells. To further assess mechanisms mediating sex differences in the renal immune profile, male and female SHR were gonadectomized to determine the impact of sex hormones. Gonadectomy increased proinflammatory markers in both sexes, suggesting that both male and female sex hormones are anti-inflammatory. In conclusion, BP contributes to sex differences in the renal T-cell profile of SHR; female SHR increase renal Tregs in response to increases in BP.

A synthetic peptide from transforming growth factor-β₁ type III receptor inhibits NADPH oxidase and prevents oxidative stress in the kidney of spontaneously hypertensive rats

AIMS

The NADPH oxidases constitute a major source of superoxide anion (·O2(-)) in hypertension. Several studies suggest an important role of NADPH oxidases in different effects mediated by transforming growth factor-β₁ (TGF-β₁). We investigated whether a chronic treatment with P144, a peptide synthesized from type III TGF-β₁ receptor, inhibited NADPH oxidases in the renal cortex of spontaneously hypertensive rats (SHR).

RESULTS

Here, we show that chronic administration of P144 significantly reduced the NADPH oxidase expression and activity as well as the oxidative stress observed in control vehicle-treated SHR (V-SHR). In addition, P144 was also able to reduce the significant increase in the renal fibrosis and in mRNA expression of different components of collagen metabolism, as well as in the levels of connective tissue growth factor observed in V-SHR. Finally, TGF-β₁-stimulated NRK52E exhibited a significant increase in NADPH oxidase expression and activity as well as a TGF-β₁-dependent intracellular pathway that were inhibited in the presence of P144.

INNOVATION

Our experimental evidence suggests that reversing oxidative stress may be therapeutically useful in preventing fibrosis-associated renal damage. We show here that (i) the TGF-β₁-NADPH oxidases axis is crucial in the development of fibrosis in an experimental hypertensive renal disease animal model, and (ii) the use of P144 reverses TGF-β₁-dependent NADPH oxidase activity; thus, P144 may be considered a novel therapeutic tool in kidney disease associated with hypertension.

CONCLUSION

We demonstrate that P144 inhibits NADPH oxidases and prevents oxidative stress in kidneys from hypertensive rats. Our data also suggest that these effects are associated with the renal antifibrotic effect of P144.

Antioxidant and pro-oxidant effects of oil palm (Elaeis guineensis) leaves extract in experimental diabetic nephropathy: a duration-dependent outcome

Background

Catechins-rich oil palm (Elaeis guineensis) leaves extract (OPLE) is known to have antioxidant activity. Several polyphenolic compounds reported as antioxidants such as quercetin, catechins and gallic acid have been highlighted to have pro-oxidant activity at high doses. Therefore, the present study was conducted to investigate the antioxidant and pro-oxidant effects of chronically administering high dose of OPLE (1000 mg kg^-1) in an animal model of diabetic nephropathy (DN).

Methods

Animal body weight, indexes of glycaemia, renal function and morphology were assessed in diabetic animals with and without OPLE (1000 mg kg^-1) for 4 and 12 weeks respectively. Oxidative stress was quantified by measuring levels of 8-hydroxy-2’-deoxyguanosine (8-OHdG), lipid peroxides (LPO) and reduced glutathione (GSH). Transforming growth factor-beta1 (TGF-β1), a key mediator of extracellular matrix accumulation, was analysed in plasma. The mechanisms of OPLE action were evaluated by assessing nicotinamide adenine dinucleotide phosphate (NADPH) oxidase subunits (p22phox and p67phox) expression.

Results

Oral administration with high dose of catechins-rich OPLE (1000 mg kg^-1) to STZ-induced diabetic rats for 4 weeks attenuated renal dysfunction (hyperfiltration, proteinuria) and development of glomerulosclerosis and tubulointerstitial fibrosis, features that are associated with DN. Suppression of increases in oxidative stress markers (8-OHdG, LPO) and the fibrotic cytokine, TGF-β1 was observed. OPLE also reduced renal expression of NADPH oxidase subunits p22phox and p67phox. In contrast and surprisingly, identical dose of OPLE when administered to diabetic animals for 12 weeks caused worsening of renal dysfunction, histopathology in addition to further elevation of oxidative stress marker (LPO) and TGF-β1. These unfavourable effects of prolonged treatment with 1000 mg kg^-1 OPLE were accompanied by increase expression of one of the NADPH oxidase subunits, p22phox.

Conclusion

Our study indicates that chronic administration of 1000 mg kg^-1 OPLE exerts both antioxidant and pro-oxidant effects in DN depending on the duration of treatment. The present study also reveals that the antioxidant/pro-oxidant effects of OPLE are in part, due to modulation of NADPH activity.

Evaluation of the antihypertensive properties of yellow passion fruit pulp (Passiflora edulis Sims f. flavicarpa Deg.) in spontaneously hypertensive rats

Various species of the genus Passiflora have been extensively used in traditional medicine as sedatives, anxiolytics, diuretics and analgesics. In the present study, after the identification and quantification of phytochemical compounds from yellow passion fruit pulp by liquid chromatography-photodiode array-mass spectrometry (HPLC-PDA-MS/MS), its antihypertensive effect was investigated on spontaneously hypertensive rats. Additionally, the renal function, evaluated by kidney/body weight, serum creatinine, proteinuria, urinary flow, reduced glutathione (GSH) levels and thiobarbituric acid-reactive substances (TBARS) and mutagenicity in bone marrow cells were assessed to evaluate the safety of passion fruit consumption. Yellow passion fruit pulp (5, 6 or 8 g/kg b.w.) was administered by gavage once a day for 5 consecutive days. HLPC-PDA-MS/MS analysis revealed that yellow passion fruit pulp contains phenolic compounds, ascorbic acid, carotenoids and flavonoids. The highest dose of passion fruit pulp significantly reduced the systolic blood pressure, increased the GSH levels and decreased TBARS. There were no changes in renal function parameters or the frequency of micronuclei in bone marrow cells. In conclusion, the antihypertensive effect of yellow passion fruit pulp, at least in part, might be due to the enhancement of the antioxidant status. The exact mechanisms responsible by this effect need further investigation.

Role of the immune system in hypertension: modulation by dietary antioxidants

Hypertension is a major health problem worldwide. Individuals with hypertension are at an increased risk for stroke, heart disease, and kidney failure. Although the etiology of essential hypertension has a genetic component, lifestyle factors such as diet play an important role. Insulin resistance is a common feature of hypertension in both humans and animal models affecting glucose and lipid metabolism producing excess aldehydes including methylglyoxal. These aldehydes react with proteins to form conjugates called advanced glycation end products (AGEs). This alters protein structure and function and can affect vascular and immune cells leading to their activation and secretion of inflammatory cytokines. AGEs also act via receptors for advanced glycation end products on these cells altering the function of antioxidant and metabolic enzymes, and ion channels. This results in an increase in cytosolic free calcium, decrease in nitric oxide, endothelial dysfunction, oxidative stress, peripheral vascular resistance, and infiltration of vascular and kidney tissue with inflammatory cells leading to hypertension. Supplementation with dietary antioxidants including vitamins C, E, or B(6), thiols such as cysteine and lipoic acid, have been shown to lower blood pressure and plasma inflammatory cytokines in animal models and humans with essential hypertension. A well-balanced diet rich in antioxidants that includes vegetables, fruits, low fat dairy products, low salt, and includes whole grains, poultry, fish and nuts, lowers blood pressure and vascular inflammation. These antioxidants may achieve their antihypertensive and anti-inflammatory/immunomodulatory effects by reducing AGEs and improving insulin resistance and associated alterations. Dietary supplementation with antioxidants may be a beneficial, inexpensive, front-line alterative treatment modality for hypertension.

Upregulation of catalase and downregulation of glutathione peroxidase activity in the kidney precede the development of hypertension in pre-hypertensive SHR

Although oxidative stress has been implicated in the pathogenesis of hypertension in spontaneously hypertensive rats (SHRs), there is little information on the levels of primary antioxidant enzymes status (AOEs) in pre-hypertensive SHR. This study therefore determined the activities of primary AOEs and their mRNA levels, levels of hydrogen peroxide (H2O2), malondialdehyde (MDA) and total antioxidant status (TAS) in whole kidneys of SHR and age-matched Wistar-Kyoto (WKY) rats aged between 2 and 16 weeks. Compared with age-matched WKY rats, catalase (CAT) activity was significantly higher from the age of 2 weeks (P<0.001) and glutathione peroxide (GPx) activity was lower from the age of 3 weeks (P<0.001) in SHR. CAT mRNA levels were significantly higher in SHR aged 2, 4, 6 and 12 weeks. GPx mRNA levels were significantly lower in SHR at 8 and 12 weeks. Superoxide dismutase activity or its mRNA levels were not different between the two strains. H2O2 levels were significantly lower in SHR from the age of 8 weeks (P<0.01). TAS was significantly higher in SHR from the age of 3 weeks (P<0.05). MDA levels were only significantly higher at 16 weeks of age in the SHR (P<0.05). The data suggest that altered renal CAT and GPx mRNA expression and activity precede the development of hypertension in SHR. The raised CAT activity perhaps contributes to the higher TAS and lower H2O2 levels in SHR. In view of these findings, the precise role of oxidative stress in the pathogenesis of hypertension in SHR needs to be investigated further.

The antihypertensive effect of arginine

Hypertension is a leading cause of morbidity and mortality worldwide. Individuals with hypertension are at increased risk of stroke, heart disease and kidney failure. Although the etiology of essential hypertension has a genetic component, lifestyle factors such as diet play an important role. Reducing dietary salt is effective in lowering blood pressure in salt-sensitive individuals. Insulin resistance and altered glucose metabolism are common features of hypertension in humans and animal models, with or without salt sensitivity. Altered glucose metabolism leads to increased formation of advanced glycation end products. Insulin resistance is also linked to oxidative stress, and alterations in the nitric oxide pathway and renin angiotensin system. A diet rich in protein containing the semiessential amino acid, arginine, and arginine treatment, lowers blood pressure in humans and in animal models. This may be due to the ability of arginine to improve insulin resistance, decrease advanced glycation end products formation, increase nitric oxide, and decrease levels of angiotensin II and oxidative stress, with improved endothelial cell function and decreased peripheral vascular resistance. The Dietary Approaches to Stop Hypertension (DASH) study demonstrated that the DASH diet, rich in vegetables, fruits and low-fat dairy products; low in fat; and including whole grains, poultry, fish and nuts, lowered blood pressures even more than a typical North American diet with similar reduced sodium content. The DASH diet is rich in protein; the blood pressure-lowering effect of the DASH diet may be due to its higher arginine-containing protein, higher antioxidants and low salt content.

The antihypertensive effect of cysteine

Hypertension is a leading cause of morbidity and mortality worldwide. Individuals with hypertension are at an increased risk for stroke, heart disease and kidney failure. Essential hypertension results from a combination of genetic and lifestyle factors. One such lifestyle factor is diet, and its role in the control of blood pressure has come under much scrutiny. Just as increased salt and sugar are known to elevate blood pressure, other dietary factors may have antihypertensive effects. Studies including the Optimal Macronutrient Intake to Prevent Heart Disease (OmniHeart) study, Multiple Risk Factor Intervention Trial (MRFIT), International Study of Salt and Blood Pressure (INTERSALT) and Dietary Approaches to Stop Hypertension (DASH) study have demonstrated an inverse relationship between dietary protein and blood pressure. One component of dietary protein that may partially account for its antihypertensive effect is the nonessential amino acid cysteine. Studies in hypertensive humans and animal models of hypertension have shown that N-acetylcysteine, a stable cysteine analogue, lowers blood pressure, which substantiates this idea. Cysteine may exert its antihypertensive effects directly or through its storage form, glutathione, by decreasing oxidative stress, improving insulin resistance and glucose metabolism, lowering advanced glycation end products, and modulating levels of nitric oxide and other vasoactive molecules. Therefore, adopting a balanced diet containing cysteine-rich proteins may be a beneficial lifestyle choice for individuals with hypertension. An example of such a diet is the DASH diet, which is low in salt and saturated fat; includes whole grains, poultry, fish and nuts; and is rich in vegetables, fruits and low-fat dairy products.

Female spontaneously hypertensive rats have greater renal anti-inflammatory T lymphocyte infiltration than males

T cells contribute to hypertension in male experimental models; data in females is lacking even though women are more likely to develop immune disorders. The goal of this study was to determine whether immune cells contribute to hypertension in female spontaneously hypertensive rats (SHR) and define the T cell profile in whole blood and kidneys of male and female SHR. We hypothesized that inflammatory cells contribute to hypertension in female SHR; however, male SHR have a higher blood pressure so we hypothesize they will have a heightened inflammatory profile. The lymphocyte inhibitor mycophenolate mofetil (MMF) was administered in a dose-dependent manner to SHR. At the highest dose (50 mg·kg(-1)·day(-1)), blood pressure was significantly decreased in both sexes, yet the percent decrease in blood pressure was greater in females (female: 12 ± 1%; males: 7 ± 1%, P = 0.01). Circulating and renal T cell profiles were defined using analytical flow cytometry. Female SHR had more circulating CD3(+), CD4(+), and pro-inflammatory CD3(+)CD4(+)RORγ(+) Th17 cells, whereas males had more immune-suppressive CD3(+)CD4(+)Foxp3(+) T regulatory cells. In the kidney, females had greater numbers of CD8(+) and T regulatory cells than males, whereas males had greater CD4(+) and Th17 cell infiltration. MMF decreased circulating and renal T cells in both sexes (P < 0.0001), although the effect of MMF on T cell subtypes was sex specific with females having greater sensitivity to MMF-induced decreases in lymphocytes. In conclusion, there is a lymphocyte contribution to the maintenance of hypertension in the female SHR and sex of the animal impacts the T cell profile.

The dietary phase 2 protein inducer sulforaphane can normalize the kidney epigenome and improve blood pressure in hypertensive rats

BACKGROUND

Our previous studies have shown that broccoli sprouts high in the glucosinolate glucoraphanin decreases renal and vascular oxidative stress and inflammation as well as blood pressure in spontaneously hypertensive stroke-prone (SHRSP) rats. The objective of this study was to determine whether the metabolite of glucoraphanin, sulforaphane, was responsible for this improved blood pressure and whether this is associated with normalization of renal methylated DNA.

METHODS

Sulforaphane was given by gavage to SHRSP and Sprague Dawley (SD) rats over 4 months and blood pressure measured under anesthesia just before euthanasia. Renovascular morphology was determined by histology and methylated deoxycytosine levels analyzed using high-performance liquid chromatography.

RESULTS

Mean arterial pressure was 20% higher in vehicle-treated SHRSP when compared to SD. Sulforaphane administration to SHRSP improved blood pressure and lowered this difference to 11%. Vehicle-treated SHRSP had significantly increased wall:lumen ratios in renal arteries, increased numbers of vascular smooth muscle cells (VSMCs), increased renal protein nitration, and decreased (11%) renal DNA methylation compared to SD. Sulforaphane administration to SHRSP significantly lowered arterial wall:lumen ratio by 35%, reduced the number of VSMCs, reduced the level of protein nitration, and increased methylated deoxycytosine levels by 14%.

CONCLUSIONS

Sulforaphane administration rectified pathological abnormalities in SHRSP kidneys and significantly improved blood pressure. This was associated with normalization of global kidney DNA methylation suggesting that DNA methylation could be associated with hypertension.

Apocynin attenuates oxidative stress and hypertension in young spontaneously hypertensive rats independent of ADMA/NO pathway

Both NADPH oxidase-derived reactive oxygen species (ROS) and asymmetric dimethylarginine (ADMA) are increased in hypertension. Apocynin, an NADPH oxidase inhibitor, could inhibit ROS, thus we tested whether apocynin can block NADPH oxidase and prevent increases of ADMA and blood pressure (BP) in spontaneously hypertensive rats (SHRs). SHRs and Wistar Kyoto (WKY) rats, aged 4 weeks, were assigned to four groups: untreated SHRs and WKY rats, SHRs and WKY rats that received 2.5 mM apocynin for 8 weeks. BP was significantly higher in SHRs compared to WKY rats, which was attenuated by apocynin. Apocynin prevented p47phox translocation in SHR kidneys, but not the increase of superoxide and H(2)O(2). Additionally, apocynin did not protect SHRs against increased ADMA. Apocynin blocks NADPH oxidase to attenuate hypertension, but has little effect on the ADMA/nitric oxide (NO) pathway in young SHRs. The reduction of ROS and the preservation of NO simultaneously might be a better approach to restoring ROS-NO balance to prevent hypertension.

Soluble epoxide hydrolase in the generation and maintenance of high blood pressure in spontaneously hypertensive rats

We hypothesized that perinatal inhibition of soluble epoxide hydrolase (SEH), which metabolizes epoxyeicosatrienoic acids in the arachidonic acid (AA) cascade, with an orally active SEH inhibitor, 12-(3-adamantan-1-yl-ureido)-dodecanoic acid (AUDA), would persistently reduce blood pressure (BP) in adult SHR despite discontinuation of AUDA at 4 wk of age. Renal cytoplasmic epoxide hydrolase-2 (Ephx2) gene expression was enhanced in SHR vs. WKY from 2 days to 24 wk. Effects of perinatal treatment with AUDA, supplied to SHR dams until 4 wk after birth, on BP in female and male offspring and renal oxylipin metabolome in female offspring were observed and contrasted to female SHR for direct effects of AUDA (8-12 wk). Briefly, inhibition of SEH was effective in persistently reducing BP in female SHR when applied during the perinatal phase. This was accompanied by marked increases in major renal AA epoxides and decreases in renal lipoxygenase products of AA. Early inhibition of SEH induced a delayed increase in renal 5-HETE at 24 wk, in contrast to a decrease at 2 wk. Inhibition of SEH in female SHR from 8 to 12 wk did not reduce BP but caused profound decreases in renal 15(S)-HETrE, LTB4, TBX2, 5-HETE, and 20-HETE and increases in TriHOMEs. In male SHR, BP reduction after perinatal AUDA was transient. Thus, Ephx2 transcription and SEH activity in early life may initiate mechanisms that eventually contribute to high BP in adult female SHR. However, programmed BP-lowering effects of perinatal SEH inhibition in female SHR cannot be simply explained by persistent reduction in renal SEH activity but rather by more complex and temporally dynamic interactions between the renal SEH, lipoxygenase, and cyclooxygenase pathways.

Proteomics in investigation of protein nitration in kidney disease: technical challenges and perspectives from the spontaneously hypertensive rat

Kidneys are the mammalian organs with widest range of oxidative status ranging from the well-perfused cortex to the relatively anoxic medulla. This organ is of key interest from the perspective of hypertension, an important contributor to human mortality, and there has been growing use of the spontaneously hypertensive rat (SHR) as a model to explore oxidative stress in hypertensive kidney. Nitrosative stress is often associated with oxidative stress and, like oxidative stress, can lead to covalent modification of protein side-chains. It is especially relevant to kidney because of high levels of both nitrite/nitrate and nitric oxide synthase in medulla. Because of their relatively low abundance and their well-known role in signal transduction, nitration of tyrosines to 3-nitrotyrosines (3NT) is of particular interest in this regard. This modification has the potential to contribute to changes in regulation, in protein activity and may provide a means of specific targeting of key proteins. Mass spectrometry (MS) offers a promising route to detecting this modification. This review surveys protein nitration in kidney disease and highlights opportunities for MS detection of nitrated residues in the SHR.

Superoxide anion and hydrogen peroxide-induced signaling and damage in angiotensin II and aldosterone action

The formation of reactive oxygen species (ROS) can be induced by xenobiotic substances, such as redox cycling molecules, but also by endogenous substances such as hormones and cytokines. Recent research shows the importance of ROS in cellular signaling. Here, the signaling pathways of the two blood pressure-regulating hormones angiotensin II and aldosterone are presented, focusing on both their physiological effects and the change of signaling owing to the action of increased concentrations or prolonged exposure. When present in high concentrations, both angiotensin II and aldosterone, as various other endogenous substances, activate NADPH oxidase, which produces superoxide. In this review the generation of superoxide anions and hydrogen peroxide in cells stimulated with angiotensin II or aldosterone, as well as the subsequently induced signaling processes and DNA damage is discussed.

Polyphenol-containing azuki bean (Vigna angularis) seed coats attenuate vascular oxidative stress and inflammation in spontaneously hypertensive rats

We investigated the effects of azuki bean (Vigna angularis) seed coats (ABSC), which contain polyphenols, on the vascular oxidative stress and inflammation associated with hypertension. Spontaneously hypertensive rats (SHR) and control normotensive Wistar-Kyoto (WKY) rats were divided into 2 groups each. One group was fed 0% ABSC; the other, a 1.0% ABSC-containing diet. Tail systolic blood pressure (SBP) was examined throughout ABSC treatment. At 8 weeks, vascular superoxide (O(2)(-)) production was measured by lucigenin-enhanced chemiluminescence. mRNA expressions of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase subunits, macrophage chemoattractant protein-1 (MCP-1) and its receptor C-C chemokine receptor 2 (CCR2) in the aorta were analyzed by reverse transcriptase-polymerase chain reaction. Protein expressions of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) were determined by western blotting. Polyphenol-containing ABSC suppressed the elevation of SBP throughout the treatment period. The NADPH-stimulated O(2)(-) level decreased significantly in the aorta of ABSC-treated SHR compared with the level of untreated SHR. The p47phox and Nox4 mRNA expression increased significantly in untreated SHR compared with that in WKY rats. Conversely, the level of p47phox mRNA was significantly lower in ABSC-treated SHR than in untreated SHR. The protein abundance of both iNOS and COX-2 was significantly decreased in the aorta of the ABSC-treated SHR compared with this abundance in untreated SHR. The MCP-1 and CCR2 mRNA expressions increased in untreated SHR, and these levels were significantly lower in ABSC-treated SHR. In conclusion, our results suggested that polyphenol-containing ABSC could attenuate vascular oxidative stress and inflammation during the progression of hypertension, and this may lead to an improvement in hypertension.

Tempol or candesartan prevents high-fat diet-induced hypertension and renal damage in spontaneously hypertensive rats

BACKGROUND

Obesity has been strongly associated with the development and aggravation of hypertension and chronic kidney disease. To date, the systemic renin-angiotensin system (RAS) has been known to involve in obesity-induced tissue damage and hypertension. However, the intrarenal mechanism whereby obesity induces and aggravates hypertension and renal disease remains poorly understood. Therefore, we investigated the role of intrarenal RAS and oxidative stress in diet-induced hypertension and renal inflammation in spontaneously hypertensive rats (SHR) fed a high-fat diet.

METHODS

Male SHR and Wistar-Kyoto rats (WKY) were divided into eight groups: normal-fat diet-fed WKY (WKY-NF), high-fat diet-fed WKY (WKY-HF), high-fat diet-fed tempol-treated WKY (WKY-HF/T), high-fat diet-fed candesartan-treated WKY (WKY-HF/C), normal-fat diet-fed SHR (SHR-NF), high-fat diet-fed SHR (SHR-HF), high-fat diet-fed tempol-treated SHR (SHR-HF/T) and high-fat diet-fed candesartan-treated SHR (SHR-HF/C). After 12 weeks of treatment, haemodynamic measurements and histological assessment of the kidney were performed.

RESULTS

At the end of week 12, the high-fat fed SHR gained more body weight, their systolic blood pressure was further elevated and glucose intolerance induced. There was no significant difference in the insulin resistance index, serum lipid profile, plasma renin activity and serum aldosterone levels according to diet. However, the high-fat diet resulted in increases in immunohistochemical stains of renin and angiotensin II in the kidney. The real-time PCR also demonstrated significant increases in mRNA levels of renin, angiotensinogen and angiotensin-converting enzyme in the kidney, reflecting enhanced activation of the intrarenal RAS, which findings were also shown by Western blot analysis for renin and angiotensin II type 1 receptor. The expression of ED-1, osteopontin and TGF-beta1 in the renal cortex were prominently enhanced in the SHR-HF group with the increased intrarenal lipid concentrations and oxidative stress. Administration of tempol or candesartan in the high-fat diet-induced SHR inhibited the elevation of the systolic blood pressure, intrarenal lipid concentrations, oxidative stress and the degree of renal inflammation to the levels of, or more than, the SHR-NF with no differences in the body weight and periepididymal fat weight, compared to those in the SHR-HF group without such treatment.

CONCLUSIONS

Our study suggests that a high-fat diet induces fatty kidneys, aggravation of blood pressure and renal inflammation in the SHR. Blockade of oxidative stress by tempol or of RAS by candesartan ameliorates the increase in blood pressure and renal inflammation and improves intrarenal lipid accumulation. Therefore, antioxidants or angiotensin receptor blockers can prevent diet-induced hypertension and renal inflammation in hypertensive rats.

Green tea (Camellia sinensis) attenuates nephropathy by downregulating Nox4 NADPH oxidase in diabetic spontaneously hypertensive rats

Green tea (GT), through its antioxidant properties, may be useful to treat or prevent human diseases. Because several lines of evidence suggest that oxidative stress contributes to the pathogenesis of diabetic nephropathy, we tested the hypothesis that GT prevents diabetes and hypertension-related renal oxidative stress, attenuating renal injury. Spontaneously hypertensive rats (SHR) with streptozotocin-induced diabetes and nondiabetic SHR were treated daily with tap water or freshly prepared GT (13.3 g/L). After 12 wk, the systolic blood pressure did not differ between treated and untreated nondiabetic or diabetic rats. However, body weight was less (P < 0.05) and glycemia was greater in diabetic SHR rats than in nondiabetic rats. Renal oxidative stress variables such as 8-hydroxy-2'-deoxyguanosine (8-OHdG) and nitrotyrosine expression, NADPH oxidase-dependent superoxide generation, and the expression of renal cortex Nox4 were greater (P < 0.05) in diabetic rats that received water (DW) than in nondiabetic rats that received water (CW). The 8-OHdG and NADPH oxidase-dependent superoxide generation were significantly less in rats treated with GT. Nitrotyrosine and Nox4 expression were significantly less in diabetic rats that received GT (DGT) than in DW. Likewise, the indices of renal injury, albuminuria, and renal expression of collagen IV were significantly greater in DW than in CW. These differences were significantly less in DGT than in DW. GT reestablished the redox state and reduced the indicators of nephropathy without altering glycemia and blood pressure levels in diabetic SHR. These findings suggest that the consumption of GT may ameliorate nephropathy in diabetic hypertensive patients.

Kidney fibrosis in hypertensive rats: role of oxidative stress

Fibrosis of the glomerulus and the tubulointerstitium occurs in patients with hypertension. Studies have shown that renal oxidative stress appears in hypertensive kidney disease. The potential role of oxidative stress in renal fibrogenesis remains to be elucidated. Herein, we tested the hypothesis that oxidative stress contributes to the development of renal fibrosis during hypertension.Sprague-Dawley rats received angiotensin II (AngII; 9 microg/h s.c.) for 4 weeks with/without co-treatment of antioxidants, apocynin and tempol (120 mg/kg/day each, p.o.). Untreated rats served as controls. Appearance of renal oxidative stress and its effect on the expression of transforming growth factor (TGF)-beta(1), population of myofibroblasts, collagen synthesis/degradation and fibrosis in kidneys were examined. Chronic AngII infusion elevated systemic blood pressure (228 +/- 6 mm Hg), which was accompanied with extensive renal fibrosis and oxidative stress represented as upregulated NADPH oxidase and suppressed superoxide dismutase (SOD). Co-treatment with antioxidants led to: (1) markedly decreased renal NADPH oxidase; (2) significantly attenuated gene expression of TGF-beta(1), type I collagen, and tissue inhibitors of matrix metalloproteinase (TIMP)-I/-II in the kidney; (3) largely reduced population of myofibroblasts in both the cortex and medulla; (4) significantly reduced renal collagen volume, and (5) partially suppressed blood pressure (190 +/- 8 mm Hg). Thus, prolonged AngII administration promotes renal oxidative stress, which is associated with hypertensive renal disease. AngII induces renal oxidative stress by increasing NADPH oxidase and reducing SOD in the kidney, which, in turn, upregulates collagen synthesis, while suppressing collagen degradation, thereby promoting the development of fibrosis in kidneys of hypertensive rats.