Attenuation of Cyclosporine-Induced Renal Dysfunction by Catechin: Possible Antioxidant Mechanism

Natural Reno-Protective Agents against Cyclosporine A-Induced Nephrotoxicity: An Overview

CA (cyclosporine A) is a powerful immunosuppressing agent that is commonly utilized for treating various autoimmune illnesses and in transplantation surgery. However, its usage has been significantly restricted because of its unwanted effects, including nephrotoxicity. The pathophysiology of CA-induced kidney injury involves inflammation, apoptosis, tubular injury, oxidative stress, and vascular injury. Despite the fact that exact mechanism accountable for CA's effects is inadequately understood, ROS (reactive oxygen species) involvement has been widely proposed. At present, there are no efficient methods or drugs for treating CA-caused kidney damage. It is noteworthy that diverse natural products have been investigated both in vivo and in-vitro for their possible preventive potential in CA-produced nephrotoxicity. Various extracts and natural metabolites have been found to possess a remarkable potential for restoring CA-produced renal damage and oxidative stress alterations via their anti-apoptosis, anti-inflammatory, and antioxidative potentials. The present article reviews the reported studies that assess the protective capacity of natural products, as well as dietary regimens, in relation to CA-induced nephrotoxicity. Thus, the present study presents novel ideas for designing and developing more efficient prophylactic or remedial strategies versus CA passive influences.

The progress and prospect of natural components in rhubarb (Rheum ribes L.) in the treatment of renal fibrosis

Background: Renal fibrosis is a key pathological change that occurs in the progression of almost all chronic kidney diseases . CKD has the characteristics of high morbidity and mortality. Its prevalence is increasing each year on a global scale, which seriously affects people’s health and quality of life. Natural products have been used for new drug development and disease treatment for many years. The abundant natural products in R. ribes L. can intervene in the process of renal fibrosis in different ways and have considerable therapeutic prospects.

Purpose: The etiology and pathology of renal fibrosis were analyzed, and the different ways in which the natural components of R. ribes L. can intervene and provide curative effects on the process of renal fibrosis were summarized. Methods: Electronic databases, such as PubMed, Life Science, MEDLINE, and Web of Science, were searched using the keywords ‘R. ribes L.’, ‘kidney fibrosis’, ‘emodin’ and ‘rhein’, and the various ways in which the natural ingredients protect against renal fibrosis were collected and sorted out.

Results: We analyzed several factors that play a leading role in the pathogenesis of renal fibrosis, such as the mechanism of the TGF-β/Smad and Wnt/β-catenin signaling pathways. Additionally, we reviewed the progress of the treatment of renal fibrosis with natural components in R. ribes L. and the intervention mechanism of the crucial therapeutic targets.

Conclusion: The natural components of R. ribes L. have a wide range of intervention effects on renal fibrosis targets, which provides new ideas for the development of new anti-kidney fibrosis drugs.

Modulatory effects of catechin hydrate on benzo[a]pyrene-induced nephrotoxicity in adult male albino rats

Benzo [a] pyrene (B[a]P) is a potent mutagen and carcinogen, considered one of the commonest concomitants in the environment. The study aimed to evaluate the effect of catechin hydrate on benzo pyrene-induced kidney toxicity. Thirty-six adult male albino rats were divided into six groups: group I untreated control, group II received 10 mL/kg of corn oil (solvent of benzo [a] pyrene) twice a week, group III received 1 mL/kg 0.5% dimethyl sulfoxide (DMSO) (solvent of catechin) once per day, group IV received 50 mg/kg body weight of benzo[a]pyrene twice a week, group V received 20 mg/kg body weight of catechin in 1 mL/kg 0.5% DMSO once daily, and group VI received both catechin+benzo [a] pyrene with the same doses. All treatment was given by oral gavage for four weeks. At the end of the experiment, blood samples were collected for biochemical investigations, tissues were obtained for genotoxicity, RT-PCR, and histopathological studies. B[a]P exposure induced an increase in serum urea and creatinine levels along with severe renal histopathological changes. Our results showed a subsequent decrease in the antioxidant enzyme activities (catalase and superoxide dismutase), and conversely, (malondialdehyde) levels markedly elevated. Also, B[a]P induced DNA damage as well as activated an apoptotic pathway confirmed by upregulation of Bax, caspase-3, and downregulation of Bcl-2 expression. However, treatment with catechin-corrected kidney functions and antioxidant enzymes as well as regulated apoptosis. Histological results also supported the protective effects of catechin. These findings suggested that catechin hydrate is an effective natural product that attenuates benzo pyrene-induced kidney toxicity.

Catechin ameliorates Porphyromonas gingivalis-induced inflammation via the regulation of TLR2/4 and inflammasome signaling

BACKGROUND

Porphyromonas gingivalis is a major periodontopathogen found in patients with chronic periodontitis that can lead to alveolar bone or tooth loss. Interleukin-1β (IL-1β), a proinflammatory cytokine, is most relevant to the pathogenesis of periodontitis. Catechin is one of the main polyphenol compounds found in green tea and possesses a range of health benefits. This study examined the anti-inflammatory effects of catechin in THP-1-derived macrophages infected with P. gingivalis as well as its effects on P. gingivalis-induced periodontitis in a mouse model.

METHODS

The cytokine levels and relevant protein expression in THP-1 cells were measured using an enzyme-linked immunosorbent assay and Western blot analysis, respectively. An apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) pyroptosome formation was measured by confocal laser scanning microscopy. Micro-computed tomography was used to determine the level of bone loss induced by a P. gingivalis oral infection.

RESULTS

Catechin attenuated the production of IL-1β by inhibiting pro-IL-1β expression via the downregulation of nuclear factor-κB, p38 mitogen-activated protein kinase, and Toll-like receptor signaling. In addition, catechin inhibited the activation of inflammasomes induced by P. gingivalis, but did not affect the growth of P. gingivalis. Catechin reduced the level of alveolar bone loss in a P. gingivalis-induced periodontitis mouse model.

CONCLUSION

Catechin possesses anti-inflammatory properties by reducing the level of IL-1β production, suggesting that it can potentially be used for the prevention and treatment of periodontal inflammation caused by P. gingivalis.

Establishment and Validation of an In Vitro Screening Method for Traditional Chinese Medicine-Induced Nephrotoxicity

Renal injury is among the adverse drug reactions (ADRs) caused by herbal medicine products (HMPs). Traditional Chinese medicines (TCMs) have been practiced for over 2000 years in China and East Asia, and herbs are currently used worldwide for the treatment and prevention of chronic and acute disease. Operetta high content analysis (HCA, PerkinElmer, Waltham, MA, USA), which is an in vitro, sensitive, reproducible, multiparametric screening method, was used to evaluate the cytotoxicity of HMPs in cultures of HEK293 human embryo kidney cells. Cytotoxic results were validated by an animal-based subacute toxicity assay. The renal safety of 18 active pharmaceutical agents from 13 TCM herbs with known nephrotoxic potential was evaluated in HEK293 human embryonic kidney cells. A panel of five parameters, cell viability, nuclear area, nuclear roundness, mitochondrial mass, and mitochondrial membrane potential, was utilized to evaluate drug-induced renal mitochondrial and nuclear injury. HCA can be a useful tool for preclinical screening and postclinical evaluation of HMPs. The nephrotoxicity of diosbulbin B and other HMPs was evident at a concentration as low as 0.01 μM.

Catechin supplementation prevents kidney damage in rats repeatedly exposed to cadmium through mitochondrial protection

Nephrotoxicity is recognized as a serious disorder affected by chronic cadmium exposure. Imbalance between radical generation and elimination is considered a critical factor involved in the initiation and progression of renal injury caused by this heavy metal. The present study investigated the possible protection by catechin, a natural phenolic antioxidant, against cadmium nephrotoxicity and elucidated its potential mechanism. Male Wistar rats were assigned to receive vehicle, cadmium (CdCl₂ 2 mg/kg, i.p.) and cadmium plus catechin (25, 50, and 100 mg/kg, orally, respectively). After 4 weeks of treatment, rats exposed to cadmium demonstrated a marked rise in blood urea nitrogen and creatinine, a fall in creatinine clearance, and renal pathologies like severe tubular damage, apoptosis, and abnormal mitochondrial structure. Significant increases in malondialdehyde, nitric oxide, and tumor necrosis factor-alpha, while reductions in antioxidant thiols, superoxide dismutase, and catalase, were also detected in the kidney tissues of cadmium-intoxicated rats. These alterations were associated with mitochondrial dysfunction as supported by an increase in mitochondrial reactive oxygen species production and a decline in mitochondrial membrane potential. Treatment with catechin significantly attenuated all the changes caused by cadmium. These findings suggest that catechin effectively protects the kidney against toxic effect of cadmium, presumably through its antioxidant, anti-inflammation, and mitochondrial protection. The study outcomes not only add evidence to reinforce the medical benefits of catechin but also, most importantly, give rise to a prospect of developing renal preventive strategy for individuals who are at risk of cadmium contamination by means of catechin supplementation.

Endothelin ETA receptor/lipid peroxides/COX-2/TGF-β1 signalling underlies aggravated nephrotoxicity caused by cyclosporine plus indomethacin in rats

BACKGROUND AND PURPOSE

Cyclosporine (CSA) and non-steroidal anti-inflammatory drugs (NSAIDs) are co-prescribed for some arthritic conditions. We tested the hypothesis that this combined regimen elicits exaggerated nephrotoxicity in rats via the up-regulation of endothelin (ET) receptor signalling.

EXPERIMENTAL APPROACH

The effects of a 10 day treatment with CSA (20 mg · kg(-1) · day(-1)), indomethacin (5 mg · kg(-1) · day(-1)) or their combination on renal biochemical, inflammatory, oxidative and structural profiles were assessed. The roles of ETA receptor and COX-2 pathways in the interaction were evaluated.

KEY RESULTS

Oral treatment with CSA or indomethacin elevated serum urea and creatinine, caused renal tubular atrophy and interstitial fibrosis, increased renal TGF-β1, and reduced immunohistochemical expressions of ETA receptors and COX-2. CSA, but not indomethacin, increased renal ET-1, the lipid peroxidation product malondialdehyde (MDA) and GSH activity. Compared with individual treatments, simultaneous CSA/indomethacin exposure caused: (i) greater elevations in serum creatinine and renal MDA; (ii) loss of the compensatory increase in GSH; (iii) renal infiltration of inflammatory cells and worsening of fibrotic and necrotic profiles; and (iv) increased renal ET-1 and decreased ETA receptor and COX-2 expressions. Blockade of ETA receptors by atrasentan ameliorated the biochemical, structural, inflammatory and oxidative abnormalities caused by the CSA/indomethacin regimen. Furthermore, atrasentan partly reversed the CSA/indomethacin-evoked reductions in the expression of ETA receptor and COX-2 protein.

CONCLUSIONS AND IMPLICATIONS

The exaggerated oxidative insult and associated dysregulation of the ETA receptor/COX-2/TGF-β1 signalling might account for the aggravated nephrotoxicity caused by the CSA/indomethacin regimen. The potential renoprotective effect of ETA receptor antagonism might be exploited therapeutically.

The effects of grape seed on apoptosis-related gene expression and oxidative stress in streptozotocin-induced diabetic rats

BACKGROUND

Diabetic nephropathy is the most common cause of end-stage renal disease. Emerging evidences indicate that many mechanistic pathways including apoptosis play an important role in the pathogenesis and progression of macrovascular and microvascular complications of diabetes mellitus. The aim of the present study is to show the effects of grape seed extract (GSE) on oxidative stress and apoptosis in the kidney of streptozotocin-induced diabetic rats.

MATERIALS AND METHODS

The study included control group, diabetic group without treatment and diabetic group treated with GSE (n=7) group. GSE was given orally (100 mg/kg/day) for six weeks. Following parameters were evaluated; oxidative stress index, caspase 1, IL1-alpha, caspase 2, IL1-beta, BCL2-associated agonist of cell death (BAD), X-linked inhibitor of apoptosis (XIAP), DNA fragmentation factor, alpha subunit and beta bubunit (DFFA, DFFB), BH3 interacting domain death agonist (BID), caspase 6, Bcl2-like 1 (BCL-XL), caspase 8, tumor necrosis factor receptor superfamily, member 1 b (TNFRSF1B) and IAP-binding mitochondrial protein (DIABLO).

RESULTS

Oxidative stress index levels were significantly increased in the kidney of diabetic group without treatment compared to control group, and decreased in diabetic+GSE group compared to diabetic group without treatment. In the kidney of diabetic group without treatment, caspase 1, IL-1 alpha, BAD, DFFA, DFFB and caspase-6 gene expressions were significantly higher compared to control group. In diabetic+GSE group caspase 1, caspase 2, XIAP, DFFA, BID, BCL-XL and TNFRSF1B genes were significantly decreased compared to control group.

CONCLUSIONS

Grape seed reduces oxidative stress and apoptosis gene expression suggesting the protective effect on diabetic nephropathy.

(+)-Catechin ameliorates diabetic nephropathy by trapping methylglyoxal in type 2 diabetic mice

SCOPE

Accumulation of glycolytic metabolite methylglyoxal (MG) in diabetic kidney is thought to contribute to the pathogenesis of nephropathy, either as a direct toxin or as a precursor for advanced glycation end products (AGEs). Using (+)-catechin (CE), a novel MG trapper, we investigated whether MG trapping is sufficient to prevent the progression of diabetic nephropathy in type 2 diabetic mice.

METHODS AND RESULTS

CE markedly trapped exogenous MG in a time- and dose-dependent manner and formed mono-MG-CE and di-MG-CE adducts, which were characterized by HPLC-ESI-Q-TOFMS. In vivo, CE administration for 16 wk significantly ameliorated renal dysfunction in type 2 diabetic db/db mice, partially due to MG trapping, which in turn inhibited AGEs formation and lowered proinflammatory cytokines, including tumor necrosis factor α and IL-1β. Similarly, the MG trapping and cellular signaling inhibition effects of CE were observed in human endothelium-derived cells under high glucose conditions.

CONCLUSION

CE might ameliorate renal dysfunction in diabetic mice as consequences of inhibiting AGEs formation and cutting off inflammatory pathway via MG trapping. Thus, CE may be a potential natural product as an MG scavenger against diabetes-related complications.

L-carnitine protects against cyclosporine-induced pancreatic and renal injury in rats

BACKGROUND

L-carnitine has protective effects against various types of injury. This study was designed to evaluate the beneficial effects of L-carnitine on pancreatic and renal injuries caused by cyclosporine (CsA).

METHODS

Rats maintained on a low sodium diet were given vehicle (olive oil, 1 mL/kg/d), CsA (15 mg/kg/d), L-carnitine (50 or 200 mg/kg/d), or a combination of CsA and L-carnitine for 4 weeks. The impact of L-carnitine on pancreatic injury was assessed by blood glucose levels, plasma insulin concentrations, and hemoglobulin A1c (HbA1c). In addition, the protective effects of L-carnitine against CsA-induced kidney injury were evaluated in terms of renal function, histopathology (inflammatory cell influx and tubulointerstitial fibrosis), oxidative stress (8-hydroxy 2'-deoxyguanosine, 8-OHdG), transforming growth factor-betal (TGF-β1), apoptosis (caspase-3), and autophagy (LC3-II).

RESULTS

CsA treatment caused diabetes, renal dysfunction, tubulointerstitial inflammation (ED-1-positive cells), and fibrosis, which were accompanied by an increase in 8-OHdG production and upregulation of TGF-β1, caspase-3, and LC3-II. Concomitant administration of L-carnitine increased plasma insulin concentrations, decreasing plasma glucose and HbA1c levels. In the kidney, L-carnitine induced dose-dependent improvement of renal function, inflammation, and fibrosis in parallel with suppression of the expression of TGF-β1 and 8-OHdG. Furthermore, the administration of L-carnitine at a high dose inhibited the expression of caspase-3 and LC3-II.

CONCLUSION

These findings suggest that L-carnitine has a protective effect against CsA-induced pancreatic and renal injuries.

Delayed treatment with oleanolic acid attenuates tubulointerstitial fibrosis in chronic cyclosporine nephropathy through Nrf2/HO-1 signaling

Background

Nuclear factor erythroid-2-related factor-2 (Nrf2) is known to protect against tissue injury by orchestrating antioxidant and detoxification responses to oxidative stress. This study investigated whether upregulation of Nrf2-dependent signaling by oleanolic acid (OA), which is known to activate Nrf2, could attenuate renal inflammation and fibrosis in cyclosporine (CsA)-induced kidney injury.

Methods

Male ICR mice were divided into four treatment groups: Vehicle (VH, n = 6), VH + OA (n = 6), CsA (n = 8), and CsA + OA (n = 8). For the OA-treated groups, OA (25 mg/kg/day) was administered by intraperitoneal injection for the final week of the 4-week experimental period. Renal function, morphologies and signaling were evaluated at the end of the study.

Results

Treatment with CsA resulted in decreased kidney function and urine osmolality and increased urine volume and urinary albumin levels. The CsA-induced changes were improved by OA treatment. Specifically, administration of OA decreased tubulointerstitial fibrosis and inflammation scores that were increased in CsA-treated mice. Furthermore, OA treatment decreased urinary 8-hydroxy-2′-deoxyguanosine (8-OHdG) and 8-epi-prostaglandin F2α (8-iso-PGF2α) levels. The beneficial effects of OA were attributed to an increased ratio of nuclear/total Nrf2 and subsequently enhanced expression of heme oxygenase (HO)-1, as well as a stable level of Kelch-like ECH-associated protein 1 (Keap1) expression, indicating that OA enhanced nuclear translocation of Nrf2. Increased apoptotic cell death and a high ratio of B cell leukaemia/lymphoma 2 (Bcl-2)-associated X protein (Bax) to Bcl-2 in CsA-treated mice were also significantly ameliorated by OA treatment.

Conclusion

Our results suggest that OA activates Nrf2/HO-1 signaling in chronic CsA nephropathy, which may have beneficial effects on inflammation and oxidative stress.

Multiple antioxidants and L-arginine modulate inflammation and dyslipidemia in chronic renal failure rats

The kidney is an important source of L-arginine, the endogenous precursor of nitric oxide (NO). Surgical problems requiring extensive renal mass reduction (RMR) decrease renal NO production, leading to multiple hemodynamic and homeostatic disorders manifested by hypertension, oxidative stress, and increased inflammatory cytokines. Using the RMR model of chronic renal failure (CRF), we assessed the effects of twelve weeks' administration of L-arginine and/or a mixture of antioxidants (L-carnitine, catechin, vitamins E and C) on plasma cytokines, soluble intercellular adhesion molecule-1 (sICAM-1), nitrate and nitrites (NO(2)/NO(3)), lipid profile, blood pressure, and renal function. CRF rats showed increased plasma IL-1 alpha, IL1-beta, IL-6, TNF-alpha, and sICAM-1 levels and decreased anti-inflammatory cytokines IL-4 and 10 levels, hypertension, and dyslipidemia. L-arginine treatment improved kidney functions, decreased systolic blood pressure, and decreased inflammatory cytokines levels. Antioxidants administration decreased inflammatory cytokines and sICAM-1 levels and increased IL-4 levels. Combined use of both L-arginine and the antioxidant mixture were very effective in their tendency to recover normal values of kidney functions, plasma cytokines, sICAM-1, blood pressure, NO(2)/NO(3), cholesterol, and triglycerides concentrations. Indeed, the effects of L-arginine and the antioxidants on the reduction of proinflammatory cytokines may open new perspectives in the treatment of uremia.

Protective effect of catechin on apoptosis of the lens epithelium in rats with N-methyl-N-nitrosourea-induced cataracts

Purpose

To investigate the effect of catechin on apoptotic cell death in the lens epithelium of rats with cataract.

Methods

Cataract was induced by intraperitoneal injection of 100 mg/kg N-methyl-N-nitrosourea (MNU) to ten day-old Sprague-Dawley rats. The neonatal rats were randomly divided into five groups (n=15 in each group): a control group, and four cataract-induction groups, treated with either 0, 50, 100, 200 mg/kg catechin. We performed slit-lamp biomicroscopic analysis, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay, Western-blot for Bcl-2 and Bax, and immunohistochemistry for caspase-3.

Results

Apoptotic cell death in lens epithelial cells that increased following cataract formation in rats was suppressed by cathechin.

Conclusions

Catechin inhibited cataract-induced apoptotic cell death in the lens epithelium and may prove useful for the prevention of cataract progression.

Lipid peroxidation and antioxidant enzyme activities in cancerous bladder tissue and their relation with bacterial infection: a controlled clinical study

It is well known that antioxidants and reactive oxygen species play an important role in carcinogenesis. In this study, we attempted to evaluate antioxidant enzyme activities and lipid peroxidation levels in cancerous bladder tissue and to determine their relationship with bacterial infection. Bacterial culture was made from all urine samples using Blood and Eosin Methylene Blue agars for checking the presence of bacterial infections. We measured thiobarbituric acid reactive substances (TBARs) and activities of xanthine oxidase (XO), superoxide dismutase (SOD), glutathione peroxidase (GSH-PX), and catalase (CAT) in cancerous tissues of 25 bladder cancer patients, in noncancerous adjacent bladder tissues of 13 out of these 25 patients, and in control bladder tissues of 15 patients with a non-neoplastic genitourinary disease. TBARs levels increased and XO, SOD, GSH-PX, and CAT activities decreased significantly in cancerous bladder tissues. TBARS, XO, and SOD levels were not significantly different between noncancerous adjacent tissue and control bladder tissue. Statistically significantly lower GSH-PX and higher CAT activities were observed in noncancerous adjacent bladder tissue compared with cancerous tissue. GSH-PX level of tumor tissue was correlated significantly with tumor grade (r=-0.425, P=0.034). Results suggested that pathway activity of free radicals were accelerated in the cancerous human bladder tissues via increased TBARs levels and decreased enzyme activities of XO, SOD, GSH-PX, and CAT, which implicated a severe exposure of cancerous tissues to oxidative stress.

S-allylcysteine attenuates renal injury by altering the expressions of iNOS and matrix metallo proteinase-2 during cyclosporine-induced nephrotoxicity in Wistar rats

Cyclosporine A (CsA) is the first choice immunosuppressant used for the prevention of allograft rejection in solid organ transplantation and immune-mediated diseases. Reactive oxygen species-induced oxidative stress and lipid peroxidation are implicated in the pathophysiology of CsA-induced renal injury. In this work, we have studied the effect of a garlic-derived compound, S-allylcysteine (SAC) on CsA-induced nephrotoxicity. CsA-induced nephrotoxicity was assessed in terms of increased activities of serum marker enzymes and levels of kidney markers. CsA administration induced significant elevation in lipid peroxidation along with abnormal levels of enzymic and non-enzymic antioxidants in the kidneys of the rats. SAC administration improved renal function by bringing about a significant decrease in peroxidative levels and increase in antioxidant status. Elevated expressions of inducible nitric oxide synthase (iNOS) and nuclear factor kappa B (NF-kappaB) due to CsA administration were reduced by SAC treatment. An increase in the expression of matrix metalloproteinase-2 (MMP-2) was evident in CsA-induced groups of rats, which was moderately reduced in SAC treated rats. An increase in the levels of serum constituent's urea, uric acid and creatinine was observed in the CsA-induced rats, which was reduced upon treatment with SAC. These results indicate that SAC has a protective action against CsA-induced nephrotoxicity which is also supported by histopathological studies. A comparative study of the antioxidant vitamin C and SAC is more valuable to assess the efficacy of the drug that can be used for the treatment of nephrotoxicity.

Black Grape and Garlic Extracts Protect Against Cyclosporine A Nephrotoxicity

The aim of this study was to determine if the natural antioxidant foods, dried black grape and garlic, protect against cyclosporine nephrotoxicity. Forty-two Sprague-Dawley rats were given Cyclosporine A (CsA) orally for 10 days, with the antioxidant food supplementation begun 3 days before CsA treatment and continued during the study period (totaling 13 days). In each group (control, CsA alone, CsA plus black grape, CsA plus aqueous garlic extract, aqueous garlic extract alone and black grape alone), there were 7 animals. At the end of the study period, the animals were sacrificed; their kidneys were removed and prepared for biochemical and histopathological investigations. Oxidant (xanthine oxidase enzyme and malondialdehyde) and antioxidant (superoxide dismutase, glutathione peroxidase and catalase enzymes) parameters were measured in the kidney tissues of the groups. Histopathological examinations of the tissues were also performed. It has been found that CsA creates oxidant load to the kidneys through both xanthine oxidase activation and impaired antioxidant defense system, which accelerates oxidation reactions in the kidney tissue. Supplementation with either dried black grape or aqueous garlic extract led to reduced malondialdehyde level in the kidney tissue possibly, by preventing oxidant reactions. In conclusion, the results suggest that impaired oxidant/antioxidant balance may play part in the CsA-induced nephrotoxicity, and some foods with high antioxidant power may ameliorate this toxicity, in agreement with studies with antioxidant vitamins.

Polymeric Micellar Delivery Reduces Kidney Distribution and Nephrotoxic Effects of Cyclosporine A After Multiple Dosing

The aim of this study was to test the ability of poly(ethylene oxide)-b-poly (epsilon-caprolactone) (PEO-b-PCL) micelles to reduce the renal uptake and nephrotoxicity of Cyclosporine A (CyA) after multiple dose administration. Sprague-Dawley rats received CyA i.v. at a dose of 20 mg/kg/day delivered as the commercial formulation (Sandimmune) or polymeric micellar formulation (PM-CyA). Cremophor EL (the solubilizing agent in Sandimmune), unloaded PEO-b-PCL micelles, or normal saline were also administered i.v. to control rats. After 7 days, kidney function was assessed through measurement of creatinine (CLcr) and urea clearances, as well as electrolyte concentrations in plasma. Blood and kidney were collected and assayed for CyA. Sandimmune administration led to decreased CLcr, and increased urea and potassium levels in plasma. In contrast, functional nephrotoxicity with the PM-CyA was not apparent, as the CLcr did not change significantly. The rate of increase in body weight in control rats was 3.1-3.4% per day. Weight gains (1.8% per day) were also noted in the rats given PM-CyA, although the body weight of animals receiving Sandimmune remained constant. Compared to Sandimmune, polymeric micelles reduced kidney uptake of CyA by 2.6-fold, and increased CyA levels in blood by 2.1-fold. The results show a potential for PEO-b-PCL micelles in restricting the nephrotoxicity of CyA.

Protective effects of a combination of quercetin and vitamin E against cyclosporine A-induced oxidative stress and hepatotoxicity in rats

AIM

Cyclosporine A (CsA) is the most widely used immunosuppressive drug in transplant surgery. It is able to generate reactive oxygen species (ROS) and cause lipid peroxidation (thiobarbituric acid-reacting substances [TBARS]), which will directly result in CsA hepatotoxicity.

METHODS

In this study, the potential of quercetin (Q) and vitamin E (E), in attenuating CsA-induced liver dysfunction in rats was investigated. Male Sprague-Dawley rats were divided into six groups and treated with either olive oil, ethanol + olive oil, CsA, CsA + E, CsA + Q, or CsA + E + Q for both 4 and 8 weeks. Hepatotoxicity was assessed by morphological alterations in tissue architecture and by reduced serum total protein and increased serum alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase.

RESULTS

The results indicated that CsA treatment increases TBARS and decreases activities of catalase (CAT) and glutathione peroxidase (GPx) in the rat liver. The co-administration of E and Q with CsA treatment improved both liver morphology changes and function. A combination of these antioxidants significantly reduced TBARS and increased CAT and GPx activities in the hepatic tissue.

CONCLUSION

Our data demonstrates that E + Q plays a protective role against the imbalance elicited by CsA between the production of free radicals and antioxidant defence systems, and suggests that a combination of these two antioxidants may find clinical application where cellular damage is a consequence of ROS.

Possible carcinogenic risks of copper gluconate and their prevention by co-administered green tea catechins evaluated by a rat medium-term multi-organ carcinogenicity bioassay protocol

Carcinogenic risks of copper gluconate, green tea catechins and their combined exposure were evaluated using a rat medium-term multi-organ carcinogenicity bioassay protocol. Male BrlHan:WIST@Jcl (GALAS) rats were given N-nitrosodiethylamine (DEN), N-methylnitrosourea (MNU), 1,2-dimethylhydrazine (DMH), N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) and 2,2'-dihydroxy-di-n-propylnitrosamine (DHPN) for a total multiple initiation period of 4 weeks (DMBDD treatment). Rats were then given a diet containing copper gluconate at a concentration of 0, 10, 300, 3000 or 6000 ppm with or without a co-administration of catechins starting 1 week later by admixing in the drinking water at a concentration of 5000 ppm. All survivors were sacrificed at the end of week 29. Number of putatively preneoplastic, glutathione S-transferase placental form-positive, liver lesions significantly increased by copper gluconate of 300 ppm or greater. In addition, both incidence and grade of hyperplasia in the forestomach significantly increased by copper gluconate of 6000 ppm. Catechins, exerting no effects by themselves, inhibited these effects of copper gluconate. The present results indicate that copper gluconate may possess carcinogenic risks for the liver and forestomach at its high dose level, and that co-administered green tea catechins may exert preventive effects.

Catechin combined with vitamins C and E ameliorates insulin resistance (IR) and atherosclerotic changes in aged rats with chronic renal failure (CRF)

Aging is an inevitable biological process associated with increased oxidative stress and accumulation of asymmetric dimethylarginine (ADMA) a known endogenous inhibitor of nitric oxide synthase. Atherosclerosis and IR constitute major risk factors for cardiovascular mortality in elderly with chronic kidney disease (CKD). We investigated the impact of catechin, vitamins E and C supplementation on insulin sensitivity, redox state, ADMA, nitrate and nitrite (NO(2)(-)/NO(3)(-)) levels and histological picture of heart and large blood vessels of aged rats with CRF. Findings of the present study revealed that aging in rats is associated with hyperinsulinemia, hyperlipidemia, IR indicated by higher homeostasis model assessment (HOMA)-index, increased lipid peroxidation product malondialdehyde (MDA), ADMA, and blood pressure (BP), but decreased antioxidant capacity and NO(2)(-)/NO(3)(-) levels. CRF exaggerated all these findings and caused thickened intima of carotid arteries and myocardial hypertrophy. Treatment with catechin, vitamins E and C increases the antioxidant capacity and NO(2)(-)/NO(3)(-) production but, decreases MDA, ADMA and BP levels. Also it keeps insulin sensitivity and normal intima/media thickness of carotid arteries. We conclude that decreased nitric oxide (NO) availability due to ADMA accumulation may be responsible for IR and associated atherosclerotic changes in aged rats with CRF. Catechin, vitamins E and C supplementation may moderate oxidative stress of renal failure, prevent ADMA accumulation, and counteract IR and atherosclerotic changes in the elderly.

COMPARISON OF THE EFFECTS OF VITAMIN E AND/OR QUERCETIN IN ATTENUATING CHRONIC CYCLOSPORINE A-INDUCED NEPHROTOXICITY IN MALE RATS

1. The aim of the present study was to investigate the effects of vitamin E and/or quercetin (Q) on renal function, oxygen radical concentrations in the kidney and some anti-oxidant enzyme activities in rats treated with cyclosporine A (CsA). 2. Groups of rats (270 +/- 15 g), on standard rat chow and water, received all their treatments by gavage for either 4 or 8 weeks. Control groups received either olive oil (0.5 mL) or 25% ethanol (0.5 mL) + olive oil (0.5 mL) per day as vehicle. All experimental groups received 25 mg CsA/kg per day in 0.5 mL olive oil. The vitamin E group received 100 mg vitamin E/kg per day in olive oil in addition to CsA treatment. The quercetin group received 15 mg of Q/kg per day in 0.5 mL of 25% ethanol in addition to CsA treatment. The vitamin E + quercetin group received the two anti-oxidants at the concentrations given in addition to CsA treatment. 3. Quercetin, at a concentration less than one-quarter of vitamin E, was more efficient in lowering blood urea nitrogen, serum creatinine and kidney malondialdehyde in CsA-treated rats. However, neither of the two anti-oxidants was able to normalize these analytes to control values after either 4 or 8 weeks treatment. 4. Quercetin (50 micromol/kg per day) elevated all renal anti-oxidant enzyme activities to values observed in the negative controls. However, vitamin E (232 micromol/kg per day) only normalized glutathione peroxidase activity at the end of either 4 or 8 weeks treatment. Combination treatment with the two anti-oxidants abolished all the ill-effects of CsA. 5. Combination treatment with the two anti-oxidants of renal transplant patients receiving CsA may be beneficial in ameliorating the chronic nephrotoxic effects of the important immunosuppressive drug CsA.

Effect of gallic acid on high fat diet-induced dyslipidaemia, hepatosteatosis and oxidative stress in rats

Gallic acid (GA) is a naturally abundant plant phenolic compound in the human diet and is known to reduce the risk of disease. In this study, the anti-obesity effect of GA in an animal model of diet-induced obesity was investigated. Obesity was induced in male Wistar rats by feeding them a high-fat diet (HFD). GA was given as a supplement at the levels of 50 and 100 mg/kg rat for a period of 10 weeks. The results showed that the body weight, organ weight of the liver and adipose tissue weights of peritoneal and epididymal tissues in the HFD+GA groups were significantly decreased as compared with the HFD group. Serum TAG, phospholipid, total cholesterol, LDL-cholesterol, insulin and leptin levels in the HFD+GA groups were significantly decreased as compared with the HFD group. Histological study showed that the lipid droplets of rats with HFD+GA diets were significantly smaller than those with HFD diets. Hepatic TAG and cholesterol levels in HFD+GA groups were significantly decreased as compared with the HFD group. Moreover, the consumption of GA reduced oxidative stress and GSSG content and enhanced the levels of glutathione, GSH peroxidase, GSH reductase and GSH S-transferase in the hepatic tissue of rats with HFD-induced obesity. These results demonstrate that intake of GA can be beneficial for the suppression of HFD-induced dyslipidaemia, hepatosteatosis and oxidative stress in rats.

Green tea extract inhibits paraquat-induced pulmonary fibrosis by suppression of oxidative stress and endothelin-l expression

Paraquat-induced pulmonary fibrosis involves two factors, direct injury by oxygen free radicals and indirect injury by inflammatory cells and fibroblasts. Endothelin-1 (ET-1) has been shown to act as a mediator of pulmonary fibrosis, and its formation increases during oxidative stress. We investigated whether green tea extract (GTE), which has antioxidant properties, inhibits paraquat-induced pulmonary fibrosis and whether ET-1 is involved in this process. Paraquat (0.3 mg/kg) was instilled into the right lungs of rats, following which the rats were either not further treated (Group P, n = 7), or they were administered 1% GTE mixed with feed (Group PG; n = 7) or the ET(A) receptor antagonist ZD2574 (10 mg/kg through gavage; Group PZ; n = 7) for two weeks. As control, we used rats instilled with saline (Group N; n = 6). Two weeks after paraquat instillation, we assayed the degree of pulmonary fibrosis by light microscopic morphometry and hydroxyproline content; lipid peroxidation as a marker of oxidative stresses by measurement of malondialdehyde (MDA); ET-1 by immunohistochemistry; and prepro-ET-1 mRNA expression by reverse transcription-polymerase chain reaction. Compared with Group N, significant pulmonary fibrosis was observed in Group P, accompanied by increases in MDA, ET-1, and prepro-ET-1 mRNA expression. Compared with Group P, Group PG showed significant decreases in pulmonary fibrosis, along with decreases in MDA, ET-1, and prepro-ET-1 mRNA expression. We also observed significant decreases in pulmonary fibrosis in Group PZ compared with Group P. These findings suggest that GTE inhibits paraquat-induced pulmonary fibrosis by suppression of oxidative stress and ET-1 expression.

Spirulina attenuates cyclosporine-induced nephrotoxicity in rats

Cyclosporine (CsA) causes a dose-related decrease in renal function in experimental animals and humans. The generation of reactive oxygen species (ROS) has been implicated in CsA-induced nephrotoxicity. It was previously shown that Spirulina, a blue-green algae, with antioxidant properties effectively attenuated the doxorubicin-induced cardiotoxicity in mice and cisplatin-induced nephrotoxicity in rat. The present study investigated the nephroprotective role of Spirulina against CsA-induced nephrotoxicity in rats. Spirulina (500 mg kg(-1) b.w.) was administered orally for 3 days before and 14 days concurrently with CsA (50 mg kg-1 b.w.). Rats treated with CsA showed nephrotoxicity as evidenced from a significant elevation in plasma urea, creatinine, urinary N-acetyl-beta-D-glucosaminidase (beta-NAG) and a decrease in creatinine and lithium clearance. Pretreatment with Spirulina protected the rats from CsA-induced nephrotoxicity. The CsA-induced rise in plasma urea and creatinine and the decrease in creatinine and lithium clearance were attenuated by Spirulina. There was a significant increase in plasma and kidney tissue MDA with CsA. Spirulina prevented the rise in plasma and kidney tissue MDA. Histopathology of the kidney from CsA-treated rats showed severe isometric vacuolization and widening of the interstitium. However, pretreatment with Spirulina prevented such changes, and the kidney morphology was comparable to that of the control. Spirulina treatment did not alter the blood CsA levels. These results suggest that Spirulina has a protective effect against nephrotoxicity induced by CsA. This study further supports the crucial role of the antioxidant nature of Spirulina in protecting against CsA-induced oxidative stress.

Catechin prevents tamoxifen-induced oxidative stress and biochemical perturbations in mice

Natural antioxidants like catechin are now known to have a modulatory role on physiological functions and biotransformation reactions involved in the detoxification process, thereby affording protection from toxic metabolic actions of xenobiotics. Reactive oxygen intermediates have been demonstrated to play an etiological role in anticancer drug-induced toxicity. This study was performed to explore the modulatory and protective effect of catechin on the toxicity of an anticancer drug, tamoxifen (TAM) with special reference to protection against disruption of glutathione metabolizing and antioxidant enzymes. TAM treatment resulted in a significant increase in the lipid peroxidation (LPO), H(2)O(2) generation and protein carbonyl (PC) contents in the liver and kidney as compared to controls while catechin+TAM-treated group showed significant decrease in LPO levels, H(2)O(2) generation and PC contents in liver and kidney when compared with TAM-treated group. Non-enzymatic antioxidants like reduced glutathione (GSH) and low molecular antioxidants like ascorbic acid (AsA) also showed normalcy due to exogenous catechin administration. Catechin pre-treatment showed restoration in the level of cytochrome P450 (CYP) content and in the activities of glutathione metabolizing enzymes, viz., glutathione-S-transferase (GST), glutathione reductase (GR) and glutathione peroxidase (GPx) and other antioxidant enzymes such as, glucose-6-phosphate dehydrogenase (G6-PD), catalase (CAT) and superoxide dismutase (SOD) in both liver and kidney when compared to TAM-treated animals. The results of the study show that catechin supplementation might be helpful in abrogation of TAM toxicity during chemotherapy. Additionally, it makes it a prophylactic and preventive agent of anticancer drug-induced oxidative stress.

Investigating the protective effects of aged garlic extract on cyclosporin-induced nephrotoxicity in rats

Cyclosporin A (CsA) nephrotoxicity has been described in solid organ recipients and in the patients who were treated for autoimmune diseases. Reactive oxygen species-induced oxidative stress and lipid peroxidations are implicated in the pathophysiology of CsA-induced renal injury. Aged garlic extract (AGE) has been reported to exhibit potent antioxidative and free radical scavenging abilities in various disease conditions. The present study was designed to investigate whether AGE could possibly have a protective effect against nephrotoxicity induced by CsA. Male Wistar rats were treated orally with CsA (50 mg/kg/day), CsA + AGE (0.25, 0.5, 1, and 2 g/kg/day started 3 days before the first dose of CsA), or the vehicle of CsA for a period of 10 days. Blood urea nitrogen, serum creatinine, creatinine clearance, and renal histopathological changes were evaluated after 24 h of the last treatment. CsA caused an increase in blood urea nitrogen and serum creatinine by 117 and 100%, respectively, whereas it decreased creatinine clearance by 78% compared with the vehicle-treated rats (all P < 0.001). AGE treatment (0.5, 1 and 2 g/kg) significantly protected animals against CsA-induced biochemical changes, albeit blood urea nitrogen and creatinine clearance in the 0.5 g/kg AGE treated-animals were only partially restored. Kidney sections taken from CsA-treated rats showed severe vacuolations and tubular necrosis. These histopathological changes were markedly improved by pretreatment of rats with AGE at the dose of 0.5--2 g/kg. The results indicate that AGE ameliorates renal dysfunction and morphological changes induced by CsA, and imply that it could be a beneficial remedy for attenuating the CsA nephrotoxicity.

Effects of cyclosporine on oxidant/antioxidant status in rat ovary tissues: Protective role of black grape extract

OBJECTIVES

It has been demonstrated that immunosuppressive drug cyclosporine A (CsA) increases the synthesis of reactive oxygen species (ROS) and lipid peroxidation products in vitro and in vivo studies, but its possible toxic effects in ovary tissue have not been defined yet. This study was designed to elucidate possible relation between CsA treatment and oxidant/antioxidant status in rat ovary tissue and, to determine if antioxidant supplementation is beneficial.

METHODS

CsA and black grape extracts were given to rats orally for 10 days. In each group (control, CsA, CsA plus black grape and black grape alone), there were 7 animals (28 rats in total). After the animals were sacrificed, their ovaries were removed to be used in the measurement of malondialdehyde (MDA) level and activities of superoxide dismutase (SOD), catalase (CAT) and xanthine oxidase (XO) enzymes.

RESULTS

In the control, CsA plus black grape and black grape alone groups, MDA levels were significantly lower than CsA group. Xanthine oxidase activities were significantly higher in CsA and CsA plus black grape groups than control group. In addition, XO activity was significantly lower in black grape alone group than all the other groups including control group. There were no significant differences in the activities of SOD and CAT enzymes between the groups.

CONCLUSION

The results suggest that CsA leads to oxidant stress and peroxidation in rat ovary tissues mainly due to increased XO activity. It has been suggested that this oxidant stress and peroxidation reactions can be prevented by antioxidant food supplementation like black grape.

Provinol prevents CsA-induced nephrotoxicity by reducing reactive oxygen species, iNOS, and NF-kB expression

Cyclosporine A (CsA) use is associated with several side effects, the most important of which is nephrotoxicity that includes, as we previously showed, tubular injury and interstitial fibrosis. Recently, many researchers have been interested in minimizing these effects by pharmacological interventions. To do this, we tested whether the administration of a red wine polyphenol, Provinol (PV), prevents the development of CsA-induced nephrotoxicity. Rats were treated for 21 days and divided into four groups: control; group treated with PV (40 mg/kg/day by oral administration in tap water); group treated with CsA (15 mg/kg/day by subcutaneous injection); group treated with CsA plus PV. CsA produced a significant increase of systolic blood pressure; it did not affect urinary output, but caused a significant decrease in creatinine clearance. These side effects were associated with an increase in conjugated dienes, which are lipid peroxidation products, inducible NO-synthase (iNOS), and nuclear factor (NF)-kB, which are involved in antioxidant damage. However, PV prevented these negative effects through a protective mechanism that involved reduction of both oxidative stress and increased iNOS and NF-kB expression induced by CsA. These results provide a pharmacological basis for the beneficial effects of plant-derived polyphenols against CsA-induced renal damage associated with CsA.

Hierarchical change in antioxidant enzyme gene expression and activity in acute cardiac rejection: Role of inducible nitric oxide synthase

Reactive oxygen and nitrogen may mediate inflammation injury, but the status of the antioxidant defense system that might influence this process is unknown. In the present study, we examined the expression profile of the antioxidant enzymes, manganese superoxide dismutase (MnSOD), catalase and glutathione peroxidase (GPX) in acutely rejecting cardiac allografts and the potential role of inducible nitric oxide synthase (iNOS) in modulating antioxidant gene expression and activity. Donor hearts from Lewis (isograft) or Wistar-Furth (allograft) rats were transplanted into Lewis recipient rats. A subset of the allografts received L-N6-(1-imino-ethyl) lysine (L-NIL), a specific iNOS inhibitor, beginning the day of surgery until the day of harvesting. Catalase and glutathione peroxidase (GPX) protein levels were significantly decreased by postoperative day 4 (POD4) and postoperative day 5 (POD5), respectively, in allografts compared to isografts. While CuZn superoxide dismutase (CuZn SOD) levels were unchanged, there was a 50% decrease in MnSOD protein in allografts at postoperative day 6 (POD6). The sequential loss in antioxidant protein levels was not due to transcriptional regulation since there was no change in RNA levels for any of the genes tested. L-NIL did not alter catalase protein; however, the loss of MnSOD protein at POD6 was prevented by L-NIL. Consistent with a decrease in antioxidant protein levels, there was a sequential loss in enzyme activity for MnSOD, catalase and GPX. L-NIL however, restored MnSOD and GPX activities but not catalase activity. Treatment with CsA restored both protein and enzyme activities of GPX and MnSOD but not catalase. These results indicate that the loss in MnSOD and GPX protein and activity in allografts occurs via an iNOS-dependent mechanism whereas the decrease in catalase appears to be iNOS-independent. This suggests a differential role for iNOS in regulating post-translational modification of individual antioxidant enzymes in acute cardiac transplantation.

Reduction of erythrocyte catalase and superoxide dismutase activities in male inhabitants of a cadmium-polluted area in Jinzu river basin, Japan

Cadmium (Cd) is a toxic heavy metal which causes oxidative damage in organisms. In this study, we investigated the activities of the antioxidant enzymes erythrocyte catalase and copper/zinc superoxide dismutase (Cu/Zn-SOD) in 22 male inhabitants of the Cd-polluted Jinzu River basin in Toyama Prefecture, Japan (Cd group). The reference group consisted of 21 male inhabitants from an area that was not polluted with Cd (reference group). Urinary Cd levels and two renal tubular dysfunction markers in urine, alpha1-microglobulin (alpha1-m) level and N-acetyl-beta-D-glucosaminidase (NAG) activity, were significantly elevated in the Cd group. Catalase and Cu/Zn-SOD activities were significantly reduced in the Cd group as compared to the reference group. Significant negative correlation was observed between the activities of these two antioxidant enzymes and urinary Cd levels. We also observed significant negative correlations between activities of these two antioxidant enzymes and the renal tubular dysfunction markers. Our results indicate that erythrocyte catalase and Cu/Zn-SOD activities are reduced as a result of long-term Cd exposure. This may be linked to renal tubular dysfunction in the inhabitants of the Cd-polluted area.