Upregulation of renal eNOS by high-sodium diet facilitates hypertension in doxorubicin-treated rats through enhanced oxidative stress

Propolis Extract Reduces Doxorubucin-Induced Brain Damage by Regulating Inflammation, ER Stress, Oxidative Stress, and Apoptosis

Doxorubicin (DOX) is the most widely used chemotherapeutic agent to treat various tumors. DOX treatment can damage many organs, including the brain, by causing oxidative stress. Several antioxidant substances can lessen the effects of DOX or make antioxidant defense systems work faster. Propolis (PROP) is a powerful agent with various healing effects, including antioxidant, antiproliferative, and anti-inflammatory. The point of this study is to look at the histopathological changes, apoptosis, and antioxidant effects of DOX on brain damage in rats. To find out what kinds of phytochemicals were in PROP from the Karlıova region of Bingöl province, ultra-high-performance liquid chromatography (UHPLC-Orbitrap-HRMS) was used. Then, we made an ethanol extract of it. A total of 28 healthy male Wistar albino rats, each 12 weeks old and weighing between 220 and 250 g, were included in the study. Rats were divided into four groups: control, PROP, DOX, and PROP+DOX. We applied the relevant treatments to the determined groups. Following the application, we decapitated the rats under the appropriate conditions and collected blood and brain tissue samples. We examined oxidative stress parameters in blood samples and used brain tissue samples for histopathological, biochemical, and molecular analyses. We determined DOX levels in the brain tissue samples using UHPLC-Orbitrap-HRMS. The findings obtained showed that the PROP extract improved DOX-induced brain tissue damage. In addition, PROP extract attenuated DOX-induced brain tissue inflammation, ER stress, apoptosis, and oxidative stress.

Silver Nanoparticles Loaded with Oleuropein Reduce Doxorubicin-Induced Testicular Damage by Regulating Endoplasmic Reticulum Stress, and Apoptosis

Doxorubicin (DOX) is the most used chemotherapeutic agent for treating solid tumors. DOX treatment may lead to testicular damage using oxidative stress, resulting in infertility. These adverse effects may be prevented by the activation of antioxidant systems. Oleuropein (OLE) is a powerful flavonoid with several ameliorative effects, including antioxidative, antiproliferative, and anti-inflammatory. It would be more efficient and applicable in treating chronic human diseases if its poor bioavailability improves with a nano-delivery system. The current study aims to assess the histopathological changes and antioxidative effects of OLE loaded with silver nanoparticles oleuropein (OLE-AgNP) on the testicular injury triggered by DOX in rats. Forty-eight male albino rats were randomly divided into six groups as follows: the control, DOX (2.5 mg/kg), OLE (50 mg/kg), AgNP (100 mg/kg), OLE + AgNP (50 mg/kg), OLE (50 mg/kg) + DOX (2.5 mg/kg), AgNP (100 mg/kg) + DOX (2.5 mg/kg), and OLE-AgNP (50 mg/kg) + DOX (2.5 mg/kg) for 11 days. Oxidative stress, inflammation, apoptosis, endoplasmic reticulum stress markers, sperm analysis, and histopathological analyses were performed on testicular tissues taken from rats decapitated after the applications and compared between the experimental groups. The tissue MDA level was lower in the OLE and OLE+AgNP-treated groups than in the DOX-treated group. In addition, SOD and GSH levels significantly increased in both the OLE and OLE+AgNP-treated groups compared to the DOX group. Both OLE and OLE+AgNP, particularly OLE+AgNP, ameliorated DOX-induced testicular tissue injury, as evidenced by reduced injury and improved seminiferous tubules and spermatocyte area. In addition, OLE and OLE+AgNP, especially OLE+AgNP, inhibited DOX-induced testicular tissue inflammation, apoptosis, and endoplasmic reticulum stress. The findings suggest that nanotechnology and the production of OLE+AgNP can ameliorate DOX-induced testicular damage.

Dapagliflozin protects against doxorubicin-induced nephrotoxicity associated with nitric oxide pathway-A translational study

Doxorubicin (Dox) is a potent anticancer agent, but its associated organ toxicity, including nephrotoxicity, restricts clinical applications. Dapagliflozin (DAPA), a sodium-glucose cotransporter-2 inhibitor, has been shown to slow the progression of kidney disease in patients with and without diabetes. However, the effect of DAPA to counteract Dox-induced nephrotoxicity remains uncertain. Therefore, in this study, we aimed to elucidate the effects of DAPA in mitigating Dox-induced nephrotoxicity. We analyzed the Taiwan National Health Insurance Database to evaluate the incidence of renal failure among breast cancer patients receiving Dox treatment compared to those without. After adjusting for age and comorbidities, we found that the risk of renal failure was significantly higher in Dox-treated patients (incidence rate ratio, 2.45; confidence interval, 1.41-4.26; p = 0.0014). In a parallel study, we orally administered DAPA to Sprague-Dawley rats for 6 weeks, followed by Dox for 4 weeks. DAPA ameliorated Dox-induced glomerular atrophy, renal fibrosis, and dysfunction. Furthermore, DAPA effectively suppressed Dox-induced apoptosis and reactive oxygen species production. On a cellular level, DAPA in HK-2 cells mitigated Dox-mediated suppression of the endothelial NOS pathway and reduced Dox-induced activities of reactive oxygen species and apoptosis-associated proteins. DAPA improved Dox-induced apoptosis and renal dysfunction, suggesting its potential utility in preventing nephrotoxicity in patients with cancer undergoing Dox treatment.

Salt Sensitivity of Blood Pressure in Blacks and Women: A Role of Inflammation, Oxidative Stress, and Epithelial Na+ Channel

Significance: Salt sensitivity of blood pressure (SSBP) is an independent risk factor for mortality and morbidity due to cardiovascular disease, and disproportionately affects blacks and women. Several mechanisms have been proposed, including exaggerated activation of sodium transporters in the kidney leading to salt retention and water. Recent Advances: Recent studies have found that in addition to the renal epithelium, myeloid immune cells can sense sodium via the epithelial Na+ channel (ENaC), which leads to activation of the nicotinamide adenine dinucleotide phosphate oxidase enzyme complex, increased fatty acid oxidation, and production of isolevuglandins (IsoLGs). IsoLGs are immunogenic and contribute to salt-induced hypertension. In addition, aldosterone-mediated activation of ENaC has been attributed to the increased SSBP in women. The goal of this review is to highlight mechanisms contributing to SSBP in blacks and women, including, but not limited to increased activation of ENaC, fatty acid oxidation, and inflammation. Critical Issues: A critical barrier to progress in management of SSBP is that its diagnosis is not feasible in the clinic and is limited to expensive and laborious research protocols, which makes it difficult to investigate. Yet without understanding the underlying mechanisms, this important risk factor remains without treatment. Future Directions: Further studies are needed to understand the mechanisms that contribute to differential blood pressure responses to dietary salt and find feasible diagnostic tools. This is extremely important and may go a long way in mitigating the racial and sex disparities in cardiovascular outcomes. Antioxid. Redox Signal. 35, 1477-1493.

Nutritional interventions based on dietary restriction and nutrient reductions for the prevention of doxorubicin chemotherapy side effects

BACKGROUND: Doxorubicin (DOX) is one of most used chemotherapeutic drugs, but it has important adverse effects. Nutrition has a critical role to prevent or minimize chemotherapy side effects. Caloric and nutrient restriction has been widely studied in different health fields showing extensive beneficial effects. Given the importance of these interventions, it is expected that some of them have benefits in patients under DOX chemotherapy. OBJECTIVE: This review aimed to compile published studies evaluating the effects of different dietary intetrventions based on restriction of calories or certain nutrients against DOX-induced damage and toxicity. RESULTS: Caloric restriction and partial reduction of fat have shown to reduce DOX cardiotoxicity correlating with a reduction of oxidative stress. Reduction of dietary fat was proved to act in the same sense at liver and kidney. Studies in relation to protein reduction is more elevated has focused only on kidneys and bone, and under certain circumstances, these interventions could increase susceptibility to DOX toxicity. CONCLUSIONS: The promising effects of restriction of dietary fat, protein and sodium on differerent organs have been supported by a greater number of studies among all the dietary interventions evaluated. Still, clinical studies are necessary to confirm the potential usefulness of these interventions.

Is renal thrombotic angiopathy an emerging problem in the treatment of ovarian cancer recurrences?

BACKGROUND AND OBJECTIVE

Ovarian cancer is usually diagnosed at an advanced stage, with most patients undergoing surgery followed by platinum- and taxane-based chemotherapy. After initial clinical remission, the majority recur, leading to additional treatments, including not only platinums and taxanes but also pegylated liposomal doxorubicin (PLD), gemcitabine, topotecan, and, more recently, bevacizumab, which may extend survival times. PLD, in particular, has been extensively studied by our group, with encouraging therapeutic results. We, however, observed instances of chronic kidney disease (CKD) developing among patients who received long-term treatment for recurrent ovarian cancer. To document the frequency and contributing factors to the emergence of CKD, we initiated a retrospective review at two institutions.

PATIENTS AND METHODS

Fifty-six consecutive patients with recurrent ovarian cancer receiving treatment at New York University Cancer Institute were reviewed for the presence of renal disease in 1997-2010. At Shaare Zedek Medical Center, 73 consecutive patients with ovarian cancer were reviewed in 2002-2010. Patients were diagnosed with CKD if they had an estimated GFR <60 mL/minute per 1.73 m2 for >3 months and were staged according to the National Kidney Foundation guidelines.

RESULTS

Thirteen patients (23%) developed stage ≥3 CKD. Three patients had renal biopsies performed that showed thrombotic microangiopathy.

CONCLUSIONS

CKD is emerging as a potential long-term consequence of current chemotherapy for recurrent ovarian cancer.

Salt-induced hemodynamic regulation mediated by nitric oxide

Excess daily salt intake impairs vasodilatation and enhances vasoconstriction, resulting in reduction of regional blood flow and elevation of blood pressure in healthy individuals and hypertensive patients with either salt sensitivity or not tested for salt sensitivity or not evaluated for salt sensitivity. The mechanism may involve decreased production of nitric oxide via endothelial nitric oxide synthase (eNOS), impaired bioavailability of nitric oxide, and elevated plasma levels of asymmetric dimethylarginine (ADMA). Experimental animals, irrespective of salt sensitivity, although less extensive in those with salt-resistance, fed a high-salt diet have deteriorated endothelial functions; the mechanisms involved include an impairment of eNOS activation, a decrease in eNOS expression, and an increase in oxidative stress and ADMA. The imbalance of interactions between nitric oxide and angiotensin II is also involved in salt sensitivity. Deficiency of nitric oxide formed via neuronal NOS and inducible NOS may contribute to salt-induced hypertension. Reduced daily salt intake, therefore, would be the most rational prophylactic measure against the development of hypertension.

The effect of salt on renal damage in eNOS-deficient mice

African Americans have an increased incidence of end-stage renal disease and are characterized as having reduced bioavailability of nitric oxide and salt-sensitivity. We propose that endothelial nitric oxide synthase (eNOS) knockout mice (eNOS(-/-)) are a suitable model of hypertension-associated renal injury as seen in African Americans. Therefore, the purpose of this study was to determine whether older eNOS(-/-) mice have hypertension-associated renal injury and if dietary salt modulates this injury. Six-month-old eNOS(-/-) mice were placed on 0.12%, 0.45% or 8% NaCl diet for 8 weeks and blood pressure measured weekly; kidneys were collected for pathology evaluation and scoring at the end of the 8-week period. Mice deficient of eNOS were hypertensive at baseline compared with control mice in all three groups (128+/-3 vs. 112+/-3, P<0.05). Blood pressure was significantly elevated from baseline in eNOS(-/-) on 0.45 and 8% salt diets (P<0.02). The composite renal pathology scores for eNOS(-/-) mice were significantly greater than wild-type mice, indicating high salt intake exacerbates the injury (P<0.001 vs. normal salt diet). eNOS(-/-) mice may be used as a model of salt-induced and hypertension-associated renal injury as seen in African Americans.

Chronic oxidative stress as a mechanism for radiation nephropathy

Suppression of the renin-angiotensin system has proven efficacy for mitigation and treatment of radiation nephropathy, and it has been hypothesized that this efficacy is due to suppression of radiation-induced chronic oxidative stress. It is known that radiation exposure leads to acute oxidative stress, but direct evidence for radiation-induced chronic renal oxidative stress is sparse. We looked for evidence of oxidative stress after total-body irradiation in a rat model, focusing on the period before there is physiologically significant renal damage. No statistically significant increase in urinary 8-isoprostane (a marker of lipid peroxidation) or carbonylated proteins (a marker of protein oxidation) was found over the first 42 days after irradiation, while a small but statistically significant increase in urinary 8-hydroxydeoxy-guanosine (a marker of DNA oxidation) was detected at 35-55 days. When we examined renal tissue from these animals, we found no significant increase in either DNA or protein oxidation products over the first 89 days after irradiation. Using five different standard methods for detecting oxidative stress in vivo, we found no definitive evidence for radiation-induced renal chronic oxidative stress. If chronic oxidative stress is part of the pathogenesis of radiation nephropathy, it does not leave widespread or easily detectable evidence behind.

Influence of salt on subcellular localization of nitric oxide synthase activity and expression in the renal inner medulla

1. The aims of this study were: (i) to characterize the subcellular localization of nitric oxide synthase (NOS) 1 and NOS3 activity and expression within the cytosolic, plasma membrane and intracellular membrane subcellular fractions of the renal inner medulla of rats; and (ii) to determine whether NOS1 and NOS3 activity and expression in subcellular fractions of the renal inner medulla are regulated by dietary salt intake. Although the NOS system is important in maintaining Na(+) and water homeostasis, the identity of the NOS isoform that is sensitive to dietary Na(+) remains unclear. In addition, subcellular localization of both NOS1 and NOS3 has been shown to regulate enzymatic activity and influence the ability of NOS to produce nitric oxide (NO). 2. Renal inner medullae were dissected from male Sprague-Dawley rats and separated into cytosolic, plasma membrane and intracellular membrane fractions for measurement of NOS activity and western blot analysis. 3. On a normal-salt diet, NOS activity and NOS1 and NOS3 protein expression were present in all three subcellular fractions, although total NOS activity was enriched in the intracellular membrane fraction. In response to a high-salt diet, urinary nitrate/nitrite (NO(x)) increased. Despite an increase in NO(x) excretion, total NOS activity in the renal inner medullary homogenate was decreased. There were no detectable differences in NOS activity in the subcellular fractions. Expression of NOS1 protein was decreased in the cytoplasmic and plasma membrane fractions, although maintained in the intracellular membrane fraction, in response to high salt. Expression of NOS3 protein was unaffected by high salt. 4. In conclusion, we hypothesize that NOS1 localization in the intracellular membrane is important in increasing NO production to aid Na(+) and water homeostasis.

Role of endothelial-derived nitric oxide in hypertension and renal disease

PURPOSE OF REVIEW

To highlight recent advances in the field of endothelial-derived nitric oxide regulation of blood pressure and renal homeostasis.

RECENT FINDINGS

Many laboratories have dissected a role for nitric oxide in regulating blood pressure and renal function. In models of hypertension, and chronic and acute renal disease, the loss of nitric oxide bioavailability may occur due to inactivation of endothelial nitric oxide synthase, synthesis of endogenous inhibitors or oxidative inactivation of nitric oxide.

SUMMARY

Understanding the molecular mechanisms of nitric oxide synthesis may lead to novel diagnostics and treatments for cardiovascular disorders.