Effects of resveratrol on glycerol-induced renal injury

Protective effects of vitamin D3 (cholecalciferol) on vancomycin-induced oxidative nephrotoxic damage in rats

CONTEXT

Vancomycin (VCM), an important antibiotic against refractory infections, has been used to treat secondary infections in severe COVID-19 patients. Regrettably, VCM treatment has been associated with nephrotoxicity. Vitamin D₃ can prevent nephrotoxicity through its antioxidant effect.

OBJECTIVE

This study tests the antioxidant effect of vitamin D₃ in the prevention of VCM-induced nephrotoxicity.

MATERIALS AND METHODS

Wistar Albino rats (21) were randomly divided into 3 groups: (A) control; (B) VCM 300 mg/kg daily for 1 week; and (C) VCM plus vitamin D₃ 500 IU/kg daily for 2 weeks. All the rats were sacrificed and serum was separated to determine kidney function parameters. Their kidneys were also dissected for histological examination and for oxidative stress markers.

RESULTS

Lipid peroxidation, creatinine, and urea levels decreased significantly (p < 0.0001) in the vitamin D₃-treated group (14.46, 84.11, 36.17%, respectively) compared to the VCM group that was given VCM (MIC<2 μg/mL) only. A significant increase was observed in superoxide dismutase levels in the vitamin D₃-treated group (p < 0.05) compared to rats without treatment. Furthermore, kidney histopathology of the rats treated with vitamin D₃ showed that dilatation, vacuolization and necrosis tubules decreased significantly (p < 0.05) compared with those in the VCM group. Glomerular injury, hyaline dystrophy, and inflammation improved significantly in the vitamin D₃ group (p < 0.001, p < 0.05, p < 0.05, respectively) compared with the VCM group.

DISCUSSION AND CONCLUSIONS

Vitamin D₃ can prevent VCM nephrotoxicity. Therefore, the appropriate dose of this vitamin must be determined, especially for those infected with COVID-19 and receiving VCM, to manage their secondary infections.

Administration of a single dose of lithium ameliorates rhabdomyolysis-associated acute kidney injury in rats

Rhabdomyolysis is characterized by muscle damage and leads to acute kidney injury (AKI). Clinical and experimental studies suggest that glycogen synthase kinase 3β (GSK3β) inhibition protects against AKI basically through its critical role in tubular epithelial cell apoptosis, inflammation and fibrosis. Treatment with a single dose of lithium, an inhibitor of GSK3β, accelerated recovery of renal function in cisplatin and ischemic/reperfusion-induced AKI models. We aimed to evaluate the efficacy of a single dose of lithium in the treatment of rhabdomyolysis-induced AKI. Male Wistar rats were allocated to four groups: Sham, received saline 0.9% intraperitoneally (IP); lithium (Li), received a single IP injection of lithium chloride (LiCl) 80 mg/kg body weight (BW); glycerol (Gly), received a single dose of glycerol 50% 5 mL/kg BW intramuscular (IM); glycerol plus lithium (Gly+Li), received a single dose of glycerol 50% IM plus LiCl IP injected 2 hours after glycerol administration. After 24 hours, we performed inulin clearance experiments and collected blood / kidney / muscle samples. Gly rats exhibited renal function impairment accompanied by kidney injury, inflammation and alterations in signaling pathways for apoptosis and redox state balance. Gly+Li rats showed a remarkable improvement in renal function as well as kidney injury score, diminished CPK levels and an overstated decrease of renal and muscle GSK3β protein expression. Furthermore, administration of lithium lowered the amount of macrophage infiltrate, reduced NFκB and caspase renal protein expression and increased the antioxidant component MnSOD. Lithium treatment attenuated renal dysfunction in rhabdomyolysis-associated AKI by improving inulin clearance and reducing CPK levels, inflammation, apoptosis and oxidative stress. These therapeutic effects were due to the inhibition of GSK3β and possibly associated with a decrease in muscle injury.

Gamma oryzanol loaded into micelle-core/chitosan-shell: from translational nephroprotective potential to emphasis on sirtuin-1 associated machineries

Gamma oryzanol (ORZ) is a nutraceutical that is poorly water soluble with poor intestinal absorption. In the current work, ORZ was nanoformulated into uncoated and chitosan coated micelles based on methoxy-poly(ethylene glycol)-b-poly(ε-caprolactone) (mPEG-PCL) and poly(ε-caprolactone)-b-methoxy-poly(ethylene glycol)-b-poly(ε-caprolactone) (PCL-PEG-PCL) copolymers for augmenting ORZ oral delivery. The physicochemical properties, morphological study, in-vitro release and safety of the nanoplaforms were determined. Importantly, the nephroprotective competence of the nanoplaforms was analyzed against acute kidney injury (AKI) rat model and the sirtuin-1 associated machineries were assessed. The results revealed that the micelles exerted particle size (PS) from 97.9 to 117.8 nm that was markedly increased after chitosan coating. The reversal of zeta potential from negative to highly positive further confirmed efficient coating. In vitro release profiles demonstrated prolonged release pattern. The nanoforms conferred higher cell viability values than free ORZ on Vero cell line. The designed micelles displayed augmented nephroprotection compared to free ORZ with the supremacy of CS coated micelles over uncoated ones in restoring kidney parameters to normal levels. The attenuated AKI was fulfilled via the modulation of sirtuin-1 signaling pathways translated by restoring the histological features, increasing renal antioxidant states, renal autophagy and decreasing renal inflammation and renal apoptosis. These outcomes confirmed that surface modification with chitosan had a considerable leverage on micelles safety, release behavior and in vivo performance.

Rhabdomyolysis-induced acute kidney injury and concomitant apoptosis induction via ROS-mediated ER stress is efficaciously counteracted by epigallocatechin gallate

Rhabdomyolysis induced acute kidney injury (RIAKI) is a life-threatening condition responsible for approximately 19-58% of AKI cases worldwide. We performed an intramuscular injection of glycerol (10 mL/kg) in male wistar rats to induce AKI. Epigallocatechin gallate (EGCG) was administered for 3 consecutive days to evaluate its protective effects. We observed significant downregulation in serum creatinine, blood urea nitrogen (BUN) and LDH at different time points on EGCG treatment groups in a dose-dependent manner. Similarly, H&E staining also revealed that EGCG was able to reduce the formation of damaged tubules and tubular necrosis which was prominently spread throughout the kidney tissue of glycerol treatment group. Concomitantly, we observed upregulated inflammation, ER stress and elevated oxidative stress in the glycerol treated group only, which was significantly normalized upon EGCG treatment in both in vitro and in vivo studies. The occurrence of apoptosis in kidney tubules was found to be relatively higher in glycerol treated group and H₂O₂ treated HEK-293 cells. The results obtained after EGCG treatment revealed a significant decrease in apoptotic cell population, which was further validated by immunofluorescence staining against p53 and comet assay in HEK-293 cells and p53 IHC in kidney tissues. Western blotting also revealed a systemic downregulation of intrinsic mitochondrial apoptotic pathway markers such as bax, bcl-2, pro and cleaved caspase 3, caspase 9 and PARP1. Additionally, the results for flow cytometry analysis and TUNEL assay corroborated apoptotic equilibrium. Conclusively, we reckon EGCG as a multi-therapeutic natural product that can be used the for treatment of AKI.

Ethnobotanical, pharmacological, phytochemical, and clinical investigations on Moroccan medicinal plants traditionally used for the management of renal dysfunctions

ETHNOPHARMACOLOGICAL RELEVANCE

Renal disease is a significant public health concern that affects people all over the world. The main limitations of conventional therapy are the adverse reaction on human health and the expensive cost of drugs. Indeed, it is necessary to develop new therapeutic strategies that are less expensive and have fewer side effects. As a consequence of their natural compounds, medicinal plants can be used as an alternative therapy to cure various ailments including kidney diseases.

OBJECTIVE

of the study: This review paper has two principal goals: (1) to inventory and describe the plants and their ancestral use by Moroccan society to cure renal problems, (2) to link traditional use with scientific confirmations (preclinical and clinical).

METHODS

To analyze pharmacological effects, phytochemical, and clinical trials of plants, selected for renal therapy, a bibliographical search was undertaken by examining ethnobotanical investigations conducted in Morocco between 1991 and 2019 and consulting peer-reviewed papers from all over the world.

RESULTS

Approximately 290 plant species, spanning 81 families and 218 genera have been reported as being utilized by Moroccans to manage renal illness. The most frequently mentioned species in Morocco were Herniaria hirsuta subsp. cinerea (DC.), Petroselinum crispum (Mill.) Fuss and Rosmarinus officinalis L. The leaves were the most frequently used plant parts, followed by the whole plant. Decoction and infusion were the most popular methods of preparation. A record of 71 plant species was studied in vitro and/or in vivo for their therapeutic efficacy against kidney disorders, including 10 plants attempting to make it to the clinical stage. Twenty compounds obtained from 15 plants have been studied for the treatment of kidney diseases.

CONCLUSION

Medicinal herbs could be a credible alternative therapy for renal illness. However, additional controlled trials are required to confirm their efficiency in patients with kidney failure. Overall, this work could be used as a database for future exploration.

Novel Chalcone BDD-39 Mitigated Diabetic Nephropathy through the Activation of Nrf2/ARE Signaling

BACKGROUND

In this study, we investigated the Nrf2/ARE signaling pathway activating capacity of Biphenyl Diester Derivative-39 (BDD-39) in diabetic nephropathy in order to elucidate the mechanism surrounding its antidiabetic potential.

OBJECTIVES

Protein expressions of Nrf2, HO-1, NQO-1 and biomarkers of kidney fibrosis were executed after which mRNA levels of Nrf2, HO-1 and NQO-1 were estimated after creating the models following BBD-39 treatment.

METHODS

Type 2 diabetes model was established in mice with high-fat diet feeding combined with streptozocin intraperitoneal administration. The diabetic mice were then treated with BDD-39 (15, 45mg· kg-1· d-1, ig) or a positive control drug resveratrol (45mg· kg-1·d-1, ig) for 8 weeks. Staining techniques were used to investigate collagen deposition in the glomerulus of the renal cortex and also to investigate the expression and localization of Nrf2 and extracellular matrix (ECM) proteins (collagen IV and laminin) in vitro and in vivo. Furthermore, we studied the mechanism of action of BDD-39 using RNA-mediated Nrf2 silencing technique in mouse SV40 glomerular mesangial cells (SV40 GM cells).

RESULTS

We found that BDD-39 activates Nrf2/ARE signaling pathway, promotes Nrf2 nuclear translocation (Nrf2nuc/Nrf2cyt) and modulate prominent biomarkers of kidney fibrosis at the protein level. However, BDD-39 could not activate Nrf2/ARE signaling in RNA-mediated Nrf2-silenced HG-cultured SV40 GM cells.

CONCLUSION

Taken together, this study demonstrates for the first time that BDD-39 ameliorates experimental DN through attenuation of renal fibrosis progression and modulation of Nrf2/ARE signaling pathway.

An updated pharmacological insight of resveratrol in the treatment of diabetic nephropathy

As one of the most common complications of diabetes, nephropathy develops in approximately 40% of diabetic individuals. Although end stage kidney disease is known as one of the most consequences of diabetic nephropathy, the majority of diabetic individuals might die from cardiovascular diseases and infections before renal replacement treatment. Moreover, the routine medical treatments for diabetes hold undesirable side effects. The explosive prevalence of diabetes urges clinicians and scientists to investigate the complementary or alternative therapies. Phytochemicals are emerging as alternatives with a wide range of therapeutic effects on various pathologies, including diabetic kidney disease. Of those phytochemicals, resveratrol, a natural polyphenolic stilbene, has been found to exert a broad spectrum of health benefits via various signaling molecules. In particular, resveratrol has gained a great deal of attention because of its anti-oxidative, anti-inflammatory, anti-diabetic, anti-obesity, cardiovascular-protective, and anti-tumor properties. In the renal system, emerging evidence shows that resveratrol has already been used to ameliorate chronic or acute kidney injury. This review critically summarizes the current findings and molecular mechanisms of resveratrol in diabetic renal damage. In addition, we will discuss the adverse and inconsistent effects of resveratrol in diabetic nephropathy. Although there is increasing evidence that resveratrol affords great potential in diabetic nephropathy therapy, these results should be treated with caution before its clinical translation. In addition, the unfavorable pharmacokinetics and/or pharmacodynamics profiles, such as poor bioavailability, may limit its extensive clinical applications. It is clear that further research is needed to unravel these limitations and improve its efficacy against diabetic nephropathy. Increasing investigation of resveratrol in diabetic kidney disease will not only help us better understand its pharmacological actions, but also provide novel potential targets for therapeutic intervention.

Toll-Like Receptors in Acute Kidney Injury

Acute kidney injury (AKI) is an important health problem, affecting 13.3 million individuals/year. It is associated with increased mortality, mainly in low- and middle-income countries, where renal replacement therapy is limited. Moreover, survivors show adverse long-term outcomes, including increased risk of developing recurrent AKI bouts, cardiovascular events, and chronic kidney disease. However, there are no specific treatments to decrease the adverse consequences of AKI. Epidemiological and preclinical studies show the pathological role of inflammation in AKI, not only at the acute phase but also in the progression to chronic kidney disease. Toll-like receptors (TLRs) are key regulators of the inflammatory response and have been associated to many cellular processes activated during AKI. For that reason, a number of anti-inflammatory agents targeting TLRs have been analyzed in preclinical studies to decrease renal damage during AKI. In this review, we updated recent knowledge about the role of TLRs, mainly TLR4, in the initiation and development of AKI as well as novel compounds targeting these molecules to diminish kidney injury associated to this pathological condition.

Acute kidney injury induced by glycerol is worsened by orchiectomy and attenuated by testosterone replacement

Although several studies have demonstrated that the male gender represents an independent risk factor for renal disease, evidence shows that androgens exert renal protective actions. The findings are controversial and no studies have evaluated the effects of orchiectomy and testosterone replacement on glycerol-induced renal injury. Male Wistar rats were submitted to orchiectomy or sham surgery and divided into four groups: SC, sham control rats injected with NaCl; SG, sham rats injected with glycerol; OG, orchiectomized rats injected with glycerol; OGT, orchiectomized rats injected with glycerol and testosterone. Testosterone was administered daily for 14 days in the OGT group. After 11 days of testosterone replacement in the OGT group, SC rats were submitted to a saline injection, while SG, OG and OGT rats received glycerol. All rats were euthanized three days after injections. OG rats presented higher serum creatinine and urea, and sodium excretion, compared to SC and SG, while testosterone attenuated these changes. Acute tubular necrosis was also mitigated by testosterone. Renal immunostaining for macrophages, lymphocytes and NF-κB was higher in OG compared to SC and SG. In addition, renal interleukin-1β, Caspase 3 and AT1 gene expression was higher in OG rats compared to SG. Testosterone attenuated these alterations, except the NF-κB immunostaining. The renal NO was lower in OG rats compared to SG. Only the OG rats presented decreases in serum NO and renal HO-1, and increased TNF-α, angiotensinogen and AT1 expression compared to SC. We conclude that orchiectomy worsened glycerol-induced kidney injury, while testosterone attenuated this renal damage.

Recovery Of Bone And Muscle Mass In Patients With Chronic Kidney Disease And Iron Overload On Hemodialysis And Taking Combined Supplementation With Curcumin And Resveratrol

Introduction

Malnutrition is common in haemodialysis patients and closely related to morbidity and mortality. We evaluated the effect of twelve weeks of supplementation with resveratrol and curcumin on recovery of bone and muscle mass and protein oxidation, lipid peroxidation on patients with chronic kidney disease and iron overload undergoing hemodialysis, we performed a randomized, double-blind, placebo-controlled trial.

Methods

We included a total of 40 patients, were randomly assigned to two groups, 20 to the group with antioxidant supplementation (Resveratrol + Curcumin) (Group A), treated with a daily oral dose of 500 mg of Resveratrol and 500 mg of Curcumin, and 20 to the control group treated with placebo (Group B).

Results

Significant differences were found in the body composition of the patients between both groups. There was a significant difference in Body Mass Index (BMI) values (p = 0.002), fat percentage (p = 0.007), muscle mass (p = 0.01) bone mass (p = 0.01), as well as in the score of the subjective global evaluation (p = 0.03). Also differences were found between the basal and final serum levels of Triglycerides (TG) (p = 0.01), VLDL (p = 0.003). A significant decrease in the levels of serum ferritin (2003.69 ± 518.73 vs 1795.65 ± 519.00 ng/mL; p = 0.04). Nor were significant differences observed between the baseline and the final Thiobarbituric Acid Reactive Substances (TBARS) values (70.45 ± 69.21 vs 50.19 ± 32.62, p = 0.24). The same results was obtained for carbonyl values (2.67 ± 0.75 vs 2.50 ± 0.85; p = 0.50).

Discussion

The present study is the first assay on patients with chronic kidney disease and iron overload that demonstrates the beneficial effects of combined supplementation with Curcumin and Resveratrol on muscle and bone mass. There was a significant decrease in circulating levels of ferritin, to finding that remarkably novel.

Protective effect of calcitriol on rhabdomyolysis-induced acute kidney injury in rats

Glycerol injection in rats can lead to rhabdomyolysis, with the release of the intracellular muscle content to the extracellular compartment and acute kidney injury (AKI). Oxidative stress and the inflammatory processes contribute to the disturbances in renal function and structure observed in this model. This study evaluated the effect of calcitriol administration in AKI induced by rhabdomyolysis and its relationship with oxidative damage and inflammatory process. Male Wistar Hannover rats were treated with calcitriol (6 ng/day) or vehicle (0.9% NaCl) for 7 days and were injected with 50% glycerol or saline 3 days after the beginning of calcitriol or saline administration. Four days after glycerol or saline injection, urine, plasma and renal tissue samples were collected for renal function and structural analysis. The oxidative stress and the inflammatory processes were also evaluated. Glycerol-injected rats presented increased sodium fractional excretion and decreased glomerular filtration rates. These alterations were associated with tubular injury in the renal cortex. These animals also presented increased oxidative damage, apoptosis, inflammation, higher urinary excretion of vitamin D-binding protein and decreased cubilin expression in renal tissue. All these alterations were less intense in calcitriol-treated animals. This effect was associated with decreases in oxidative damage and inflammation.

Application of Herbal Traditional Chinese Medicine in the Treatment of Acute Kidney Injury

Acute kidney injury (AKI) is a clinical syndrome characterized by a rapid loss of renal function, which may further develop into chronic kidney damage (CKD) or even end-stage renal disease (ESRD). AKI is a global health problem associated with high morbidity and costly treatments, and there is no specific or effective strategy to treat AKI. In recent years, Traditional Chinese Medicine (TCM) has attracted more attention, with lines of evidence showing that application of TCM improved AKI, and the mechanisms of action for some TCMs have been well illustrated. However, reviews summarizing the progress in this field are still lacking. In this paper, we reviewed TCM preparations and TCM monomers in the treatment of AKI over the last 10 years, describing their renal protective effects and mechanisms of action, including alleviating inflammation, programmed cell death, necrosis, and reactive oxygen species. By focusing on the mechanisms of TCMs to improve renal function, we provide effective complementary evidence to promote the development of TCMs to treat AKI. Moreover, we also summarized TCMs with nephrotoxicity, which provides a more comprehensive understanding of TCMs in the treatment of AKI. This review may provide a theoretical basis for the clinical application of TCMs in the future.

Prior intake of Brazil nuts attenuates renal injury induced by ischemia and reperfusion

Introduction:

Ischemia-reperfusion (IR) injury results from inflammation and oxidative stress, among other factors. Because of its anti-inflammatory and antioxidant properties, the Brazil nut (BN) might attenuate IR renal injury.

Objective:

The aim of the present study was to investigate whether the intake of BN prevents or reduces IR kidney injury and inflammation, improving renal function and decreasing oxidative stress.

Methods:

Male Wistar rats were distributed into six groups (N=6/group): SHAM (control), SHAM treated with 75 or 150 mg of BN, IR, and IR treated with 75 or 150 mg of BN. The IR procedure consisted of right nephrectomy and occlusion of the left renal artery with a non-traumatic vascular clamp for 30 min. BN was given daily and individually for 7 days before surgery (SHAM or IR) and maintained until animal sacrifice (48h after surgery). We evaluated the following parameters: plasma creatinine, urea, and phosphorus; proteinuria, urinary output, and creatinine clearance; plasmatic TBARS and TEAC; kidney expression of iNOS and nitrotyrosine, and macrophage influx.

Results:

Pre-treatment with 75 mg of BN attenuated IR-induced renal changes, with elevation of creatinine clearance and urinary output, reducing proteinuria, urea, and plasmatic phosphorus as well as reducing kidney expression of iNOS, nitrotyrosine, and macrophage influx.

Conclusion:

Low intake of BN prior to IR-induced kidney injury improves renal function by inhibition of macrophage infiltration and oxidative stress.

Previous Exercise Training Reduces Markers of Renal Oxidative Stress and Inflammation in Streptozotocin-Induced Diabetic Female Rats

The aim of this study is to evaluate the effects of regular moderate exercise training initiated previously or after induction of diabetes mellitus on renal oxidative stress and inflammation in STZ-induced diabetic female rats. For this purpose, Wistar rats were divided into five groups: sedentary control (SC), trained control (TC), sedentary diabetic (SD), trained diabetic (TD), and previously trained diabetic (PTD). Only the PTD group was submitted to treadmill running for 4 weeks previously to DM induction with streptozotocin (40 mg/kg, i.v). After confirming diabetes, the PTD, TD, and TC groups were submitted to eight weeks of exercise training. At the end of the training protocol, we evaluated the following: glycosuria, body weight gain, plasma, renal and urinary levels of nitric oxide and thiobarbituric acid reactive substances, renal glutathione, and immunolocalization of lymphocytes, macrophages, and nuclear factor-kappa B (NF-κB/p65) in the renal cortex. The results showed that exercise training reduced glycosuria, renal TBARS levels, and the number of immune cells in the renal tissue of the TD and PTD groups. Of note, only previous exercise increased weight gain and urinary/renal NO levels and reduced NF-κB (p65) immunostaining in the renal cortex of the PTD group. In conclusion, our study shows that exercise training, especially when initiated previously to diabetes induction, promotes protective effects in diabetic kidney by reduction of renal oxidative stress and inflammation markers in female Wistar rats.

Allopurinol attenuates rhabdomyolysis-associated acute kidney injury: Renal and muscular protection

BACKGROUND

Acute kidney injury (AKI) is the most severe complication of rhabdomyolysis. Allopurinol (Allo), a xanthine oxidase inhibitor, has been in the spotlight in the last decade due to new therapeutic applications related to its potent antioxidant effect. The aim of this study was to evaluate the efficacy of Allo in the prevention and treatment of rhabdomyolysis-associated AKI.

METHODS

Male Wistar rats were divided into five groups: saline control group; prophylactic Allo (300mg/L of drinking water, 7 days); glycerol (50%, 5ml/kg, IM); prophylactic Allo + glycerol; and therapeutic Allo (50mg/Kg, IV, 30min after glycerol injection) + glycerol.

RESULTS

Glycerol-injected rats showed markedly reduced glomerular filtration rate associated with renal vasoconstriction, renal tubular damage, increased oxidative stress, apoptosis and inflammation. Allo ameliorated all these alterations. We found 8-isoprostane-PGF_2a (F2-IsoP) as a main factor involved in the oxidative stress-mediated renal vasoconstriction following rhabdomyolysis. Allo reduced F2-IsoP renal expression and restored renal blood flow. Allo also reduced oxidative stress in the damaged muscle, attenuated muscle lesion/inflammation and accelerated muscular recovery. Moreover, we showed new insights into the pathogenesis of rhabdomyolysis-associated AKI, whereas Allo treatment reduced renal inflammation by decreasing renal tissue uric acid levels and consequently inhibiting the inflammasome cascade.

CONCLUSIONS

Allo treatment attenuates renal dysfunction in a model of rhabdomyolysis-associated AKI by reducing oxidative stress (systemic, renal and muscular), apoptosis and inflammation. This may represent a new therapeutic approach for rhabdomyolysis-associated AKI - a new use for an old and widely available medication.

Nephroprotective effect of ethanolic extract of Azima tetracantha root in glycerol induced acute renal failure in Wistar albino rats

The gravity of the impact of renal failure on human health is well known and as there is no specific pharmacotherapy for renal failure, the current study was undertaken to evaluate the effect of root extract of Azima tetracantha, an ancient medicinal plant used in Siddha and Ayurvedhic systems of medicine. The experiment was done in glycerol-induced acute renal failure in Wistar albino rats. Thirty rats were divided into five groups. Group 1 was given normal saline (10 ml/kg) per oral, group 2 with single dose of hypertonic glycerol (8 ml/kg) by intramuscular injection into the hind limbs, group 3 with glycerol and ethanolic extract of A. tetracantha root (ATR) 250 mg/kg, group 4, glycerol and ATR 500 mg/kg and group 5, 500 mg/kg ATR. Extract was given orally 60 min prior to glycerol injection. 24 h urine output, serum creatinine, blood urea nitrogen, total proteins and albumin were measured for all the groups. Kidneys were examined for histopathological changes. The antioxidant activity of the extract was tested in vitro and in vivo. Rats treated with ATR showed significant improvement in biochemical parameters and histopathological changes compared to glycerol treated group. The protective effect was highly significant at 500 mg/kg. Both in vitro and in vivo assays showed significant antioxidant activity. The in vitro activity was comparable to vitamin-C. The ethanolic extract of ATR has nephroprotective effect in glycerol-induced acute renal failure and the mechanism of action could be the antioxidant effect.

Pharmacological models and approaches for pathophysiological conditions associated with hypoxia and oxidative stress

Hypoxia is the failure of oxygenation at the tissue level, where the reduced oxygen delivered is not enough to satisfy tissue demands. Metabolic depression is the physiological adaptation associated with reduced oxygen consumption, which evidently does not cause any harm to organs that are exposed to acute and short hypoxic insults. Oxidative stress (OS) refers to the imbalance between the generation of reactive oxygen species (ROS) and the ability of endogenous antioxidant systems to scavenge ROS, where ROS overwhelms the antioxidant capacity. Oxidative stress plays a crucial role in the pathogenesis of diseases related to hypoxia during intrauterine development and postnatal life. Thus, excessive ROS are implicated in the irreversible damage to cell membranes, DNA, and other cellular structures by oxidizing lipids, proteins, and nucleic acids. Here, we describe several pathophysiological conditions and in vivo and ex vivo models developed for the study of hypoxic and oxidative stress injury. We reviewed existing literature on the responses to hypoxia and oxidative stress of the cardiovascular, renal, reproductive, and central nervous systems, and discussed paradigms of chronic and intermittent hypobaric hypoxia. This systematic review is a critical analysis of the advantages in the application of some experimental strategies and their contributions leading to novel pharmacological therapies.

Resveratrol attenuates renal injury and fibrosis by inhibiting transforming growth factor-β pathway on matrix metalloproteinase 7

Renal injury has a strong relationship to the subsequent development of renal fibrosis. In developing renal fibrosis, tubular epithelial cells in the kidney underwent epithelial-mesenchymal transition (EMT). Matrix metalloproteinase 7 (MMP7) was reported to reduce E-cadherin and induce EMT by up-regulation of β-catenin/lymphoid enhancer-binding factor 1 (LEF1) signaling. In this research, we tried to evaluate the role of resveratrol (RSV) on EMT process in renal injury and fibrosis. Human tubular epithelial cell HK-2 cells were treated with aristolochic acid (AAs) and transforming growth factor-β(TGF-β) to induce EMT with or without the administration of RSV. The inhibitory role of RSV on EMT in renal injury and fibrosis was determined by Western blotting, real-time PCR, and immunofluorescence staining. The EMT repressing role of RSV was also evaluated in vivo by renal ischemia-reperfusion (I/R) injury and unilateral ureteral obstruction (UUO) models. The underlying mechanism was investigated by shRNA interfering MMP7 and sirtuin 1 (SIRT1) expression. The results indicated that RSV reversed human kidney 2 (HK-2) cell EMT, renal I/R injury, and renal fibrosis. MMP7 inhibition was responsible for RSV-induced EMT repression. SIRT1 was up-regulated by RSV inhibited TGF-β pathway on MMP7 via deacetylating Smad4. In conclusion, RSV attenuated renal injury and fibrosis by inhibiting EMT process which was attributed to the fact that the up-regulated SIRT1 by RSV deacetylated Smad4 and inhibited MMP7 expression.

Pathophysiological role of different tubular epithelial cell death modes in acute kidney injury

The histological substrate of many forms of intrinsic acute kidney injury (AKI) has been classically attributed to tubular necrosis. However, more recent studies indicate that necrosis is not the main form of cell death in AKI and that other forms such as apoptosis, regulated necrosis (i.e. necroptosis and parthanatos), autophagic cell death and mitotic catastrophe, also participate in AKI and that their contribution depends on the cause and stage of AKI. Herein, we briefly summarize the main characteristics of the major types of cell death and we also critically review the existing evidence on the occurrence of different types of cell death reported in the most common experimental models of AKI and human specimens. We also discuss the pathophysiological mechanisms linking tubule epithelial cell death with reduced glomerular filtration, azotaemia and hydroelectrolytic imbalance. For instance, special relevance is given to the analysis of the inflammatory component of some forms of cell death over that of others, as an important and differential pathophysiological determinant. Finally, known molecular mechanisms and signalling pathways involved in each cell death type pose appropriate targets to specifically prevent or reverse AKI, provided that further knowledge of their participation and repercussion in each AKI syndrome is progressively increased in the near future.

Anti-Inflammatory and Organ-Protective Effects of Resveratrol in Trauma-Hemorrhagic Injury

Resveratrol, a natural polyphenolic compound of grape and red wine, owns potential anti-inflammatory effects, which results in the reduction of cytokines overproduction, the inhibition of neutrophil activity, and the alteration of adhesion molecules expression. Resveratrol also possesses antioxidant, anti-coagulation and anti-aging properties, and it may control of cell cycle and apoptosis. Resveratrol has been shown to reduce organ damage following traumatic and shock-like states. Such protective phenomenon is reported to be implicated in a variety of intracellular signaling pathways including the activation of estrogen receptor, the regulation of the sirtuin 1/nuclear factor-kappa B and mitogen-activated protein kinases/hemeoxygenase-1 pathway, and the mediation of proinflammatory cytokines and reactive oxygen species formation and reaction. In the recent studies, resveratrol attenuates hepatocyte injury and improves cardiac contractility due to reduction of proinflammatory mediator expression and ameliorates hypoxia-induced liver and kidney mitochondrial dysfunction following trauma and hemorrhagic injuries. Moreover, through anti-inflammatory effects and antioxidant properties, the resveratrol is believed to protect organ function in trauma-hemorrhagic injury. In this review, the organ-protective and anti-inflammatory effects of resveratrol in trauma-hemorrhagic injury will be discussed.

Macrophage depletion ameliorates glycerol-induced acute kidney injury in mice

BACKGROUND

This study was conducted to elucidate the role of renal macrophages in the development of acute kidney injury (AKI) in a glycerol (Gly)-induced rhabdomyolysis mouse model.

METHODS

The experimental model of rhabdomyolysis requires injecting 50% Gly (10 ml/kg) intramuscularly into mice. Control mice were injected into the tail vein with the liposomal vehicle. Liposome-encapsulated clodronate (LEC)-only mice were injected with LEC. Gly-only mice were injected with Gly into a hind limb. LEC+Gly-treated mice were injected intravenously with 100 μl of LEC 24 h prior to Gly injection. Mice were sacrificed 24 h after Gly injection.

RESULTS

Gly injection increased the serum creatinine level, and induced tubular damage. Renal CD45(+)CD11b(+)Ly6c(+) or CD45(+)CD11b(+)Ly6c(+)F4/80(+) macrophages were decreased by pretreatment with LEC in both normal and injured kidneys. Macrophage depletion prevented Gly-induced apoptotic death of tubular epithelial cells by decreasing caspase-9, ERK and p53, while increasing Bcl-2 expression. Expression of the inflammatory mediators NF-κB, MCP-1, ICAM-1, iNOS and COX-2 were also decreased with LEC pretreatment of mice injected with Gly.

CONCLUSION

These results support the hypothesis that depletion of macrophages prevents renal dysfunction by abrogating apoptosis and attenuating inflammation during AKI.

The heme oxygenase system suppresses perirenal visceral adiposity, abates renal inflammation and ameliorates diabetic nephropathy in Zucker diabetic fatty rats

The growing incidence of chronic kidney disease remains a global health problem. Obesity is a major risk factor for type-2 diabetes and renal impairment. Perirenal adiposity, by virtue of its anatomical proximity to the kidneys may cause kidney disease through paracrine mechanisms that include increased production of inflammatory cytokines. Although heme-oxygenase (HO) is cytoprotective, its effects on perirenal adiposity and diabetic nephropathy in Zucker-diabetic fatty rats (ZDFs) remains largely unclear. Upregulating the HO-system with hemin normalised glycemia, reduced perirenal adiposity and suppressed several pro-inflammatory/oxidative mediators in perirenal fat including macrophage-inflammatory-protein-1α (MIP-1α), endothelin (ET-1), 8-isoprostane, TNF-α, IL-6 and IL-1β. Furthermore, hemin reduced ED1, a marker of pro-inflammatory macrophage-M1-phenotype, but interestingly, enhanced markers associated with anti-inflammatory M2-phenotype such as ED2, CD206 and IL-10, suggesting that hemin selectively modulates macrophage polarization towards the anti-inflammatory M2-phenotype. These effects were accompanied by increased adiponectin, HO-1, HO-activity, atrial-natriuretic peptide (ANP), and its surrogate marker, urinary-cGMP. Furthermore, hemin reduced renal histological lesions and abated pro-fibrotic/extracellular-matrix proteins like collagen and fibronectin that deplete nephrin, an important transmembrane protein which forms the scaffolding of the podocyte slit-diaphragm allowing ions to filter but not massive excretion of proteins, hence proteinuria. Correspondingly, hemin increased nephrin expression in ZDFs, reduced markers of renal damage including, albuminuria/proteinuria, but increased creatinine-clearance, suggesting improved renal function. Conversely, the HO-blocker, stannous-mesoporphyrin nullified the hemin effects, aggravating glucose metabolism, and exacerbating renal injury and function. The hemin effects were less-pronounced in Zucker-lean controls with healthy status, suggesting greater selectivity of HO in ZDFs with disease. We conclude that the concomitant reduction of pro-inflammatory/oxidative mediators, macrophage infiltration and profibrotic/extracellular-matrix proteins, coupled to increased nephrin, adiponectin, ANP, cGMP and creatinine clearance may account for improved renal function in hemin-treated ZDFs. These findings suggest that HO-inducers like hemin may be explored against the co-morbidity of perirenal adiposity and diabetic nephropathy.

Renal protective effects of resveratrol

Resveratrol (3,5,4′-trihydroxystilbene), a natural polyphenolic compound found in grapes and red wine, is reported to have beneficial effects on cardiovascular diseases, including renal diseases. These beneficial effects are thought to be due to this compound's antioxidative properties: resveratrol is known to be a robust scavenger of reactive oxygen species (ROS). In addition to scavenging ROS, resveratrol may have numerous protective effects against age-related disorders, including renal diseases, through the activation of SIRT1. SIRT1, an NAD⁺-dependent deacetylase, was identified as one of the molecules through which calorie restriction extends the lifespan or delays age-related diseases, and this protein may regulate multiple cellular functions, including apoptosis, mitochondrial biogenesis, inflammation, glucose/lipid metabolism, autophagy, and adaptations to cellular stress, through the deacetylation of target proteins. Previous reports have shown that resveratrol can ameliorate several types of renal injury, such as diabetic nephropathy, drug-induced injury, aldosterone-induced injury, ischemia-reperfusion injury, sepsis-related injury, and unilateral ureteral obstruction, in animal models through its antioxidant effect or SIRT1 activation. Therefore, resveratrol may be a useful supplemental treatment for preventing renal injury.

Immune and inflammatory role in renal disease

Chronic and acute renal diseases, irrespective of the initiating cause, have inflammation and immune system activation as a common underlying mechanism. The purpose of this review is to provide a broad overview of immune cells and inflammatory proteins that contribute to the pathogenesis of renal disease, and to discuss some of the physiological changes that occur in the kidney as a result of immune system activation. An overview of common forms of acute and chronic renal disease is provided, followed by a discussion of common therapies that have anti-inflammatory or immunosuppressive effects in the treatment of renal disease.

Montelukast abrogates rhabdomyolysis-induced acute renal failure via rectifying detrimental changes in antioxidant profile and systemic cytokines and apoptotic factors production

In addition to antiasthmatic effect, the cysteinyl leukotriene receptor 1 (CysLT₁) antagonist montelukast shows renoprotective effect during ischemia/reperfusion and cyclosporine-induced renal damage. Here, we proposed that montelukast protects against rhabdomyolysis-induced acute renal failure. Compared with saline-treated rats, at 48 h following the induction of rhabdomyolysis using intramuscular glycerol (10 ml 50% glycerol/kg), significant elevations in serum levels of urea, creatinine, phosphate and acute renal tubular necrosis were observed. This was associated with elevations in serum Fas, interleukin-10, tumor necrotic factor-alpha, and transforming growth factor-beta1 and renal malondialdehyde and nitrite and detrimental reductions in renal catalase and superoxide dismutase activities. The effects of rhabdomyolysis on renal functional, biochemical and structural integrity and the associated changes in cytokines and Fas levels were abolished upon concurrent administration of montelukast (10 mg/kg i.p.) for 3 days (1 day before and 2 days after induction of rhabdomyolysis). Alternatively, administration of the anti-oxidant, α-tocopherol (400 mg/kg i.m.) for 3 days, succeeded in alleviating renal oxidative stress, but had no significant effect on the circulating levels of most cytokines and partially restored kidney functional and structural damage. Serum level of interleukin-6 was not altered by rhabdomyolysis but showed significant elevations in rats treated with montelukast or α-tocopherol. Collectively, motelukast abrogated functional and structural renal damage induced by rhabdomyolysis via ameliorating renal oxidative stress and modulation of systemic cytokines and apoptotic factors production. The results of this work are expected to open new avenues for early prevention of rhabdomyolysis-induced acute renal failure using selective CysLT₁ antagonists such as montelukast.

Recovery from glycerol-induced acute kidney injury is accelerated by suramin

Acute kidney injury (AKI) is a common and potentially life-threatening complication after ischemia/reperfusion and exposure to nephrotoxic agents. In this study, we examined the efficacy and mechanism(s) of suramin in promoting recovery from glycerol-induced AKI, a model of rhabdomyolysis-induced AKI. After intramuscular glycerol injection (10 ml of 50% glycerol per kilogram) into male Sprague-Dawley rats, serum creatinine maximally increased at 24 to 72 h and then decreased at 120 h. Creatinine clearance (CrCl) decreased 75% at 24 to 72 h and increased at 120 h. Suramin (1 mg/kg i.v.) administered 24 h after glycerol accelerated recovery of renal function as demonstrated by increased CrCl, decreased renal kidney injury molecule-1, and improved histopathology 72 h after glycerol injection. Suramin treatment decreased interleukin-1β (IL-1β) mRNA, transforming growth factor-β(1) (TGF-β(1)), phospho-p65 of nuclear factor-κB (NF-κB), and cleaved caspase-3 at 48 h compared with glycerol alone. Suramin treatment also decreased glycerol-induced activation of intracellular adhesion molecule-1 (ICAM-1) and leukocyte infiltration at 72 h. Urinary/renal neutrophil gelatinase-associated lipocalin 2 (NGAL) levels, hemeoxygenase-1 expression, and renal cell proliferation were increased by suramin compared with glycerol alone at 72 h. Mechanistically, suramin decreases early glycerol-induced proinflammatory (IL-1β and NF-κB) and growth inhibitory (TGF-β(1)) mediators, resulting in the prevention of late downstream inflammatory effects (ICAM-1 and leukocyte infiltration) and increasing compensatory nephrogenic repair. These results support the hypothesis that delayed administration of suramin is effective in abrogating apoptosis, attenuating inflammation, and enhancing nephrogenic repair after glycerol-induced AKI.

Effects of resveratrol on biomarkers of oxidative stress and on the activity of delta aminolevulinic acid dehydratase in liver and kidney of streptozotocin-induced diabetic rats

The present study investigated the effects of resveratrol (RV), a polyphenol with potent antioxidant properties, on oxidative stress parameters in liver and kidney, as well as on serum biochemical parameters of streptozotocin (STZ)-induced diabetic rats. Animals were divided into six groups (n = 8): control/saline; control/RV 10 mg/kg; control/RV 20 mg/kg; diabetic/saline; diabetic/RV10 mg/kg; diabetic/RV 20 mg/kg. After 30 days of treatment with resveratrol the animals were sacrificed and the liver, kidney and serum were used for experimental determinations. Results showed that TBARS levels were significantly increased in the diabetic/saline group and the administration of resveratrol prevented this increase in the diabetic/RV10 and diabetic/RV20 groups (P < 0.05). The activities of catalase (CAT), superoxide dismutase (SOD) and aminolevulinic acid dehydratase (δ-ALA-D) and the levels of non protein thiols (NPSH) and vitamin C presented a significant decrease in the diabetic/saline group when compared with the control/saline group (P < 0.05). The treatment with resveratrol was able to prevent these decrease improving the antioxidant defense of the diabetic/RV10 and diabetic/RV20 groups (P < 0.05). In addition, the elevation in serum alanine aminotransferase (ALT), aspartate aminotransferase (AST) and γ-glutamiltransferase (γ-GT) activities as well as in levels of urea, creatinine, cholesterol and triglycerides observed in the diabetic/saline group were reverted to levels close to normal by the administration of resveratrol in the diabetic/RV10 and diabetic/RV20 groups (P < 0.05). These findings suggest that resveratrol could have a protector effect against hepatic and renal damage induced by oxidative stress in the diabetic state, which was evidenced by the capacity of this polyphenol to modulate the antioxidant defense and to decrease the lipid peroxidation in these tissues.

Oxidative stress as a mechanism underlying sulfasalazine-induced toxicity

INTRODUCTION

Sulfasalazine (SASP) is a drug commonly used in the treatment of inflammatory bowel diseases (IBD) such as ulcerative colitis and Crohn's disease (CD) and rheumatoid arthritis (RA). A high incidence of side effects limits therapy with this drug. Getting a wider knowledge of drug pharmacology, indications and side effects is essential to ensure the best possible clinical care, minimizing toxicity and inappropriate use.

AREAS COVERED

This paper gives an overview of recent research about SASP and its main adverse effects, highlighting the mechanisms underlying them. To give an overview and comment on the data available so far on this topic, relevant literature was identified using a PubMed search of articles published up to December 2009. Search terms included: 'sulfasalazine', 'oxidative stress, 'renal effects', 'hepatotoxicity' and 'male fertility'. Original papers were reviewed and relevant citations from these articles were also considered.

EXPERT OPINION

Although SASP and 5-aminosalicylic acid also scavenge ROS, which may account for some of their anti-inflammatory properties, the reaction with ROS may also generate toxic free radicals; hence, the ability of other antioxidants to suppress the toxicity of SASP in vivo. Further investigations, particularly about SASP mechanism, are still needed.

Macrophage depletion attenuates chronic cyclosporine A nephrotoxicity

BACKGROUND

Cyclosporine A (CsA)-induced chronic nephrotoxicity is characterized by renal dysfunction and interstitial fibrosis. Early and progressive renal macrophage influx, correlating with latter interstitial fibrotic areas, has been associated with CsA treatment. This study investigated the role of macrophages, the nitric oxide (NO) pathway, and the oxidative stress on chronic CsA nephrotoxicity.

METHODS

The macrophages were depleted by clodronate liposomes. Animals were distributed into four groups: vehicle (olive oil for 21 days), CsA 7.5 mg/kg per day (21 days), CsA plus clodronate (5 mg/mL intraperitoneally on days -4, 1, 4, 11, and 18 of CsA treatment), or vehicle plus clodronate. On day 22, glomerular filtration rate, renal blood flow, renal tubulointerstitial fibrosis, CsA blood levels, serum malondialdehyde and renal tissue immunohistochemistry for macrophages, inducible NO synthase, transforming growth factor-beta, nuclear factor-kbeta, alpha-smooth muscle actin, vimentin, and nitrotyrosine were assessed.

RESULTS

CsA-induced increase in the macrophage was prevented by clodronate. Macrophage depletion attenuated the reductions in the glomerular filtration rate and renal blood flow, the development of tubulointerstitial fibrosis, malondialdehyde increase and increases in nuclear factor-kbeta, transforming growth factor-beta, vimentin, inducible NO synthase, and nitrotyrosine expression provoked by CsA. Clodronate did not affect alpha-smooth muscle actin expression and CsA blood levels.

CONCLUSIONS

Renal macrophage influx plays an important role in CsA-induced chronic nephrotoxicity. The NO pathway and oxidative stress are likely mechanisms involved in the genesis of this form of renal injury.

Resveratrol, a dietary polyphenolic phytoalexin, is a functional scavenger of peroxynitrite

Oxidant damage from reactive oxygen species (ROS) and reactive nitrogen species (RNS) is a major contributor to the cellular damage seen in numerous types of renal injury. Resveratrol (trans-3,4',5-trihydroxystilbene) is a phytoalexin found naturally in many common food sources. The anti-oxidant properties of resveratrol are of particular interest because of the fundamental role that oxidant damage plays in numerous forms of kidney injury. To examine whether resveratrol could block damage to the renal epithelial cell line, mIMCD-3, cells were exposed to the peroxynitrite donor 5-amino-3-(4-morpholinyl)-1,2,3-oxadiazolium chloride (SIN-1). Resveratrol produced a concentration-dependent inhibition of cytotoxicity induced by SIN-1. To examine the mechanism of protection, resveratrol was incubated with authentic peroxynitrite and found to block nitration of bovine serum albumin with an EC(50) value of 22.7 microM, in contrast to the known RNS scavenger, N-acetyl-l-cysteine, which inhibited nitration with an EC(50) value of 439 microM. These data suggested that resveratrol could provide functional protection by directly scavenging peroxynitrite. To examine whether resveratrol was a substrate for peroxynitrite oxidation, resveratrol was reacted with authentic peroxynitrite. Resveratrol nitration products and dimers were detected using liquid chromatograph with tandem electrospray mass spectrometry. Similar products were detected in the media of cells treated with SIN-1 and resveratrol. Taken collectively, the data suggest that resveratrol is able to provide functional protection of renal tubular cells, at least in part, by directly scavenging the RNS peroxynitrite. This property of resveratrol may contribute to the understanding of its anti-oxidant activities.

Involvement of catalase in the protective effect of binaphthyl diselenide against renal damage induced by glycerol

In the present study, the protective effect of binapthyl diselenide [(NapSe)(2)] was investigated on glycerol-induced renal damage in rats. Adult male Wistar rats were treated with (NapSe)(2) (50 mg/kg, orally) or vehicle. After 24 h (NapSe)(2) treatment, the animals received an intramuscular injection of glycerol (8 ml/kg, dissolved in saline) or vehicle as a divided dose into the hind limbs. Twenty-four hours afterwards, rats were euthanized and the levels of urea and creatinine were measured in plasma. Non-protein thiol (NPSH) levels and catalase (CAT) activity were evaluated in renal homogenates. Histopathological evaluations were also performed in kidneys of rats. The rats exposed to glycerol presented swelling of the proximal and distal tubules with evidence of cell damage and death. Glycerol-exposed rats presented an increase in renal failure markers (plasmatic urea and creatinine levels) and a reduction in renal CAT activity. No change was observed in NPSH levels in kidneys of rats exposed to glycerol. (NapSe)(2) protected against the alterations caused by glycerol in rats. (NapSe)(2) increased per se NPSH levels (33%) in kidneys of rats. In conclusion, the results demonstrated that treatment with (NapSe)(2) protected against renal damage induced by glycerol in rats, probably due to its antioxidant effect.

Diphenyl diselenide protects against glycerol-induced renal damage in rats

In this study we evaluated the effect of diphenyl diselenide (PhSe)(2) on glycerol-induced acute renal failure in rats. Rats were pre-treated by gavage every day with (PhSe)(2 )(7.14 mg kg(-1)) for 7 days. On the eighth day, rats received an intramuscular injection of glycerol (8 mL kg(-1)). Twenty-four hours afterwards, rats were euthanized and the levels of urea and creatinine were measured in plasma. Catalase (CAT), glutathione peroxidase (GPx), glutathione S-transferase (GST), delta-aminolevulinate dehydratase (delta-ALA-D) and Na(+), K(+)-ATPase activities and ascorbic acid levels were evaluated in renal homogenates. Histopathological evaluations were also performed. The results demonstrated that (PhSe)(2) was able to protect against the increase in urea and creatinine levels and histological alterations in kidney induced by glycerol. (PhSe)(2) protected against the inhibition in delta-ALA-D, CAT and GPx activities and the reduction in ascorbic acid levels induced by glycerol in kidneys of rats. In conclusion, the present results indicate that (PhSe)(2) was effective in protecting against acute renal failure induced by glycerol.

Effect of resveratrol on tubular damage and interstitial fibrosis in kidneys of rats exposed to cigarette smoke

The aim of this study was to evaluate the effect of resveratrol on kidney tissue of rats exposed to cigarette smoke. Forty adult male Wistar Albino rats were divided into four groups. Animals in group 1 was the control group. For 6 weeks, group 2 was exposed to cigarette smoke; group 3 received daily intraperitoneal injections of resveratrol (10 mg/kg/d); and group 4 was exposed to both cigarette smoke and intraperitoneal resveratrol. All rats were sacrificed with cervical dislocation. The kidney tissues were obtained, fixed in Bouin's fixative and embeded in paraffin blocks. Samples were sectioned to 4-5 microns thickness, stained with hematoxylin/eosin (H/E), Masson's trichromic, periodic acid-schiff (PAS) and were examined by light microscopy for tubular injury and interstitial fibrosis. Results were compared by non-parametric tests. Hydropic degeneration, tubular atrophy, tubulo-interstitial fibrosis, interstitial cell infiltration, vacuolar degeneration and desquamation were prominent in group 2. In group 4, hydropic degeneration, epithelial cell vacuolization and desquamation was not observed, but occasional tubular atrophy and dilation were observed. Our study suggests that, some morphological alterations in the rat kidney, due to cigarette smoke may be prevented by resveratrol.

Is the use of resveratrol in the treatment and prevention of obesity premature?

Obesity is a multi-faceted disease, predisposing sufferers to numerous co-morbidities such as epithelial dysfunction and insulin resistance which ultimately result in CVD. Visceral adipose tissue in particular is associated with inflammation due to the release of pro-inflammatory cytokines by adipocytes. Inflammation seems to be rather central in causing damage to endothelial cells as well as exerting negative effects on glucose metabolism, ultimately leading to insulin resistance. Resveratrol is a naturally occurring phenolic substance which has been found to display anti-inflammatory, vasoprotective and insulin-sensitising effects, among others. The popularity of resveratrol use is escalating in the treatment of various ailments including obesity in adults. The use of the substance in childhood obesity is, however, a worrying factor, as no studies have as yet been performed on adolescent animals and there is evidence of kidney toxicity of resveratrol and its metabolites at intake levels below those currently approved as safe. Another cause for concern is the uncertainty surrounding long-term, low-dose administration of the substance in humans. The supplement should thus not be recommended for use in the prevention and treatment of obesity until conclusive research is established on the safety of long-term usage of resveratrol in both children and adults.

Inhibition of suicidal erythrocyte death by resveratrol

AIMS

Pleiotropic effects of resveratrol include antioxidant activity and inhibition of cyclooxygenase with decrease of PGE(2) formation. In erythrocytes oxidation and PGE(2) activate Ca(2+)-permeable cation channels. The Ca(2+)-entry leads to activation of Ca(2+)-sensitive K(+) channels with subsequent cell shrinkage and cell membrane scrambling with phosphatidylserine exposure at the erythrocyte surface. Cell shrinkage and phosphatidylserine exposure are hallmarks of suicidal erythrocyte death or eryptosis. Eryptotic cells adhere to the vascular wall thus compromising microcirculation and are cleared from circulating blood thus leading to anemia. The present experiments explored whether resveratrol influences eryptosis.

MAIN METHODS

Erythrocyte phosphatidylserine exposure was identified by annexin V-binding, cell volume estimated from forward scatter and cytosolic Ca(2+) activity determined utilizing Fluo3 fluorescence in FACS analysis.

KEY FINDINGS

Energy depletion (48 h glucose removal) significantly increased Fluo3 fluorescence and annexin V-binding and decreased forward scatter, effects significantly blunted by resveratrol (>/=5 microM). Moreover, oxidative stress (30 min 0.3 mM tert-butylhydroperoxide) and isoosmotic cell shrinkage (48 h replacement of extracellular chloride by gluconate) similarly triggered eryptosis, effects again significantly blunted in the presence of resveratrol.

SIGNIFICANCE

Resveratrol is a potent inhibitor of suicidal erythrocyte death during energy depletion, oxidative stress and isoosmotic cell shrinkage. The nutrient could thus counteract anemia and impairment of microcirculation under conditions with excessive eryptosis.

Protective effect of resveratrol on acute endotoxemia-induced nephrotoxicity in rat through nitric oxide independent mechanism

Lipopolysaccharide (LPS) is a glycolipid component of the cell wall of gram negative bacteria inducing deleterious effects on the kidney. Endotoxemia-induced nephrotoxicity is characterized by disturbed intracellular redox balance and reactive oxygen species (ROS) accumulation leading to DNA, proteins and membrane lipid damages. Resveratrol (trans-3,5,4'-trihydroxystilbene) is a polyphenol displaying antioxidant and anti-inflammatory properties. This study investigated its effects on LPS-induced nephrotoxicity in rats. Resveratrol counteracted all LPS-induced changes in renal haemodynamic parameters. In the kidney resveratrol abrogated LPS-induced lipoperoxidation and antioxidant enzyme activities depletion as superoxide dismutase (SOD) and catalase (CAT) but not peroxidase (POD) activity. LPS increased plasma and urine nitric oxide (NO) level and resveratrol reversed them. More importantly, LPS-induced iron mobilization from plasma to kidney, which was also abolished by resveratrol treatment. All these results suggest that resveratrol exerted strong antioxidant properties against LPS-induced nephrotoxicity and that its mode of action seemed to involve iron shuttling proteins.

Potential of resveratrol in anticancer and anti-inflammatory therapy

Phytochemicals present in food have shown significant prospects in the treatment and management of a vast array of human diseases. Resveratrol is a stilbene-type aromatic phytoalexin predominantly found in grapes, peanuts, berries, turmeric, and other food products. Resveratrol has been reported to exhibit several physiological activities including anticancer and anti-inflammatory activities in vitro and in experimental animal models, as well as in humans. Anticancer activity of this compound is mainly due to induction of apoptosis via several pathways, as well as alteration of gene expressions, all leading to a decrease in tumor initiation, promotion, and progression. Resveratrol exhibits anti-inflammatory activity through modulation of enzymes and pathways that produce mediators of inflammation and also induction of programmed cell death in activated immune cells. Resveratrol has been shown to produce no adverse effects, even when consumed at high concentrations. Hence, resveratrol possesses good potential to be used as an adjunctive or alternative therapy for cancer and inflammatory diseases.

Lipid peroxidation and antioxidant status in kidney and liver of rats treated with sulfasalazine

Sulfasalazine (SASP) is a drug commonly used in the treatment of inflammatory bowel diseases (IBD). In this study, the changes in endogenous antioxidant capacity and oxidative damage in liver and kidney of SASP-treated rats were investigated. Adult male Sprague-Dawley rats were orally given 0, 300, or 600 mg SASP/kg body weight for 14 days. One half of the animals in each group remained 14 additional days without SASP treatment. At the end of the experimental period, rats were euthanized and liver and kidney were removed. In both organs, the following stress markers were determined: reduced glutathione (GSH), oxidized glutathione (GSSG), glutathione reductase (GR), glutathione peroxidase (GPx), glutathione-S-transferase (GST), superoxide dismutase (SOD), catalase (CAT), and thiobarbituric acid-reactive substances (TBARS). Moreover, histological examination of kidneys showed phagolysosomes after 14 days of SASP withdrawal. A dropsical degeneration was also observed in renal tissue. Oral SASP administration induced a significant increase in TBARS levels in both liver and kidney. After 2 weeks without SASP administration, a recovery of these levels was noted. SOD activity was significantly reduced, while CAT activity significantly increased at 600 mg SASP/(kg day). In kidney, GPx activity significantly increased, while GST activity and GSH levels were significantly reduced at 600 mg SASP/(kg day). These results suggest that in male rats, oxidative damage can be a mechanism for nephro- and hepatotoxicity related with SASP treatment.

Troxerutin protects the mouse kidney from d-galactose-caused injury through anti-inflammation and anti-oxidation

This study was carried out to investigate the protective effect of troxerutin against D-galactose (D-gal)-induced renal injury in mice. Hematoxylin and eosin (H&E) stained sections of kidneys revealed D-gal could cause renal injury and troxerutin could significantly attenuate the injury. We further investigated the mechanisms involved in the protective effects of troxerutin on mouse kidney. The following antioxidant defense enzymes were measured: cytosolic Cu/Zn superoxide dismutase (SOD-1), catalase (CAT) and glutathione peroxidase (GPx). The content of the lipid peroxidation product malondialdehyde (MDA) was also analyzed. In D-gal-treated mice, antioxidant enzymes activities were significantly decreased and the level of MDA was significantly higher than those in the vehicle controls. Our results indicated that the protective effect of troxerutin against D-gal induced renal injury might be caused, at least in part, by increasing the activity of antioxidant enzymes with a reduction in lipid peroxidation product. Furthermore, we also examined the inflammatory signal mediators of nuclear factor-kappaB (NF-kappaB), inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2) and prostanoid receptor subtype EP2 by Western blot. After treatment with D-gal, the NF-kappaB p65, iNOS, COX-2 and EP2 were markedly upregulated. Upon co-treatment with the troxerutin, however, the expressions of the NF-kappaB p65, iNOS, COX-2 and EP2 markedly reduced, compared to D-gal treatment alone. These results indicated that troxerutin has significantly inhibitory effects on the NF-kappaB-mediated inflammatory response. These findings suggest troxerutin could attenuate renal injury induced by D-gal probably through its antioxidant and anti-inflammation properties.