Prevention of renal ischemia/reperfusion-induced injury in rats by leflunomide

Leflunomide Treatment Does Not Protect Neural Cells following Oxygen-Glucose Deprivation (OGD) In Vitro

Neonatal hypoxia-ischemia (HI) affects 2-3 per 1000 live births in developed countries and up to 26 per 1000 live births in developing countries. It is estimated that of the 750,000 infants experiencing a hypoxic-ischemic event during birth per year, more than 400,000 will be severely affected. As treatment options are limited, rapidly identifying new therapeutic avenues is critical, and repurposing drugs already in clinical use offers a fast-track route to clinic. One emerging avenue for therapeutic intervention in neonatal HI is to target mitochondrial dysfunction, which occurs early in the development of brain injury. Mitochondrial dynamics are particularly affected, with mitochondrial fragmentation occurring at the expense of the pro-fusion protein Optic Atrophy (OPA)1. OPA1, together with mitofusins (MFN)1/2, are required for membrane fusion, and therefore, protecting their function may also safeguard mitochondrial dynamics. Leflunomide, an FDA-approved immunosuppressant, was recently identified as an activator of MFN2 with partial effects on OPA1 expression. We, therefore, treated C17.2 cells with Leflunomide before or after oxygen-glucose deprivation, an in vitro mimic of HI, to determine its efficacy as a neuroprotection and inhibitor of mitochondrial dysfunction. Leflunomide increased baseline OPA1 but not MFN2 expression in C17.2 cells. However, Leflunomide was unable to promote cell survival following OGD. Equally, there was no obvious effect on mitochondrial morphology or bioenergetics. These data align with studies suggesting that the tissue and mitochondrial protein profile of the target cell/tissue are critical for taking advantage of the therapeutic actions of Leflunomide.

Mitochondrial dynamics in the neonatal brain - a potential target following injury?

The impact of birth asphyxia and its sequelae, hypoxic–ischaemic (HI) brain injury, is long-lasting and significant, both for the infant and for their family. Treatment options are limited to therapeutic hypothermia, which is not universally successful and is unavailable in low resource settings. The energy deficits that accompany neuronal death following interruption of blood flow to the brain implicate mitochondrial dysfunction. Such HI insults trigger mitochondrial outer membrane permeabilisation leading to release of pro-apoptotic proteins into the cytosol and cell death. More recently, key players in mitochondrial fission and fusion have been identified as targets following HI brain injury. This review aims to provide an introduction to the molecular players and pathways driving mitochondrial dynamics, the regulation of these pathways and how they are altered following HI insult. Finally, we review progress on repurposing or repositioning drugs already approved for other indications, which may target mitochondrial dynamics and provide promising avenues for intervention following brain injury. Such repurposing may provide a mechanism to fast-track, low-cost treatment options to the clinic.

The protective effects of sinapic acid on acute renal ischemia/reperfusion injury

Objectives

The aim of this research was to investigate whether sinapic acid (SA) can alleviate oxidative damage, apoptosis, and inflammation in I/R induced renal injury.

Methods

A total of 24 male rats were randomly separated into four groups as six rats in each group. Group 1 (Sham), Group 2 (I/R), Group 3 (I/R + SA, 10 mg/kg), Group 4 (I/R + SA, 20 mg/kg). In order to evaluate kidney function serum BUN, Cr, and AST were measured in an autoanalyzer. SOD, GSH-Px, MDA, PC and NO oxidative stress parameters were measured with spectrophotometric methods and TNF-α, IL-1β, IL-6, KIM-1 and NGAL parameters were measured with the ELISA method. In addition, H&E method and immunohistochemical examinations were performed for histological evaluations of kidney tissue.

Results

SA significantly decreases the increase in kidney damage, inflammation, oxidative stress, cell death and restore the decrease in antioxidant enzyme activities (p<0.05). Pre-treatment of the rats with SA reduces kidney dysfunction and morphological changes.

Conclusions

The development of oxidative stress and lipid peroxidation seems to be the leading factors that accelerate inflammation and cell death during renal IRI. The antioxidant, anti-inflammatory, and anti-apoptotic features of SA displayed a renoprotective effect.

Renoprotective Effects of Origanum majorana Methanolic L and Carvacrol on Ischemia/Reperfusion-Induced Kidney Injury in Male Rats

Background. The most important cause of acute renal failure in normal kidneys is ischemia-reperfusion (I/R) injury. The aim of the current study was to investigate the protective effects of Origanum majorana (OM) methanolic extract, carvacrol, and vitamin E on I/R-induced kidney injury in male rats. Material and Method. Thirty Wistar male rats were randomly allocated into 5 groups; sham, I/R, I/R + OM (300 mg/kg), I/R + carvacrol (75 mg/kg), and I/R + vitamin E (100 mg/kg). Renal function markers, oxidant-antioxidant parameters, and histopathological examination were evaluated. Results. It was exhibited that the urea, creatinine, protein carbonyl, glomerular filtration rate, total thiol, ferric reducing antioxidant power, and histopathological changes markedly reversed in the treatment groups with OM or carvacrol in comparison to the I/R merely group. Conclusion. We conclude that OM extract or its ingredient, carvacrol, exerts renoprotective impacts in I/R-induced kidney injury possibly by scavenging free radicals and increasing antioxidant power.

Notoginsenoside R1 Suppresses Inflammatory Signaling and Rescues Renal Ischemia-Reperfusion Injury in Experimental Rats

Background

Notoginsenoside R1 (NR) is a major dynamic constituent of Panax notoginseng found to possess anti-inflammatory activity against various inflammatory diseases. However, its protective effects against renal ischemia-reperfusion (I/R) injury have not been elucidated. In male Wistar rats, we induced I/R under general anesthesia by occluding the renal artery for 60 min, followed by reperfusion and right nephrectomy.

Material/Methods

Rats were randomized to 4 groups: a sham group, an I/R group, an NR-pretreated (50 mg/kg) before I/R induction group, and an NR control group. All animals were killed at 72 h after I/R induction. Blood and renal tissues were collected, and histological and basic renal function parameters were assessed. In addition, levels of various kidney markers and proinflammatory cytokines were measured using RT-PCR, ELISA, and immunohistochemistry analysis.

Results

After I/R induction, the onset of renal dysfunction was shown by the elevated levels of serum urea, creatinine levels, and histological evaluation, showing a 2-fold increase in the renal failure markers kim-1 and NGAL compared to control rats. Rats pretreated with NR before I/R induction had significantly better renal functions, with attenuated levels of oxidative markers, restored levels of inflammatory cytokines such as tumor necrosis factor-α (TNF-α), tumor growth factor-β1 (TGF-β1), INF-γ, and IL-6, and increased anti-inflammatory cytokine levels (IL-10) compared to I/R-induced rats.

Conclusions

NR suppressed I/R-induced inflammatory cytokines production by suppressing oxidative stress and kidney markers, suggesting that NR is a promising drug candidate for prevention, progression, and treatment of renal dysfunction.

The Effects of Administration of Vitamin D, Infliximab, and Leflunomide on Testosterone Concentrations in Rats under Atorvastatin Therapy

Objective

Statins inhibit the 3-hydroxy-3-methyl-glutaryl-CoA (HMG-CoA) reductase enzyme and thus reduce plasma cholesterol levels. Although decreased cholesterol level is the main target of anti-lipidemic drugs, cholesterol has an important role in the synthesis of lipid-based hormones such as testosterone. In this study, the alterations in serum testosterone levels were examined in rats under atorvastatin therapy and their responses to vitamin D, infliximab, and leflunomide supplementation were evaluated.

Materials and Methods

Wistar rats were treated with atorvastatin (100 mg/kg) for 21 days to induce inhibition of the HMG-CoA reductase enzyme activity. Following statin therapy, rats received vitamin D (0.2 μg/kg/day) orally for 15 days, infliximab (7 mg/kg/day) intraperitoneally in two doses, or leflunomide (10 mg/kg/day) orally in two doses. Subsequently, the alterations in serum testosterone levels were measured by ELISA.

Results

Atorvastatin led to a decrease in the testosterone level compared to the vehicle group. Administration of vitamin D, infliximab, and leflunomide under HMG-CoA inhibition insignificantly increased the testosterone level compared to the atorvastatin control group. Furthermore, it appears that rats under statin administration respond better to treatment with leflunomide by achieving a greater induction in testosterone levels than with vitamin D or infliximab.

Conclusion

Our data provide evidence that administration of vitamin D, infliximab, and leflunomide in rats under atorvastatin treatment may ameliorate the serum testosterone levels.

Antioxidant Properties of Crocus Sativus L. and Its Constituents and Relevance to Neurodegenerative Diseases; Focus on Alzheimer's and Parkinson's Disease

BACKGROUND

Reactive oxygen species and reactive nitrogen species, which are collectively called reactive oxygen-nitrogen species, are the inevitable by-products of cellular metabolic redox reactions, such as oxidative phosphorylation in the mitochondrial respiratory chain, phagocytosis, reactions of biotransformation of exogenous and endogenous substrata in endoplasmic reticulum, eicosanoid synthesis, and redox reactions in the presence of metal with variable valence. Among medicinal plants, there is growing interest in Crocus Sativus L. It is a perennial, stemless herb, belonging to Iridaceae family, cultivated in various countries such as Greece, Italy, Spain, Israel, Morocco, Turkey, Iran, India, China, Egypt and Mexico.

OBJECTIVE

The present study aims to address the protective role of Crocus Sativus L. in neurodegeneration with an emphasis in Parkinson's and Alzheimer's disease.

MATERIALS AND METHODS

An electronic literature search was conducted by two of the authors from 1993 to August 2017. Original articles and systematic reviews (with or without meta-analysis), as well as case reports were selected. Titles and abstracts of papers were screened by a third reviewer to determine whether they met the eligibility criteria, and full texts of the selected articles were retrieved.

RESULTS

Hence, the authors focused on the literature concerning the role of Crocus Sativus L. on its anti-oxidant and neuroprotective properties.

CONCLUSION

Literature findings represented in current review herald promising results for using Crocus Sativus L. and/or its active constituents as antioxidants, anti-inflammatory, and neuroprotective agents.

The Protective Role of Crocus Sativus L. (Saffron) Against Ischemia- Reperfusion Injury, Hyperlipidemia and Atherosclerosis: Nature Opposing Cardiovascular Diseases

Background:

Reactive oxygen species and reactive nitrogen species, which are collective-ly called reactive oxygen-nitrogen species, are inevitable by-products of cellular metabolic redox reac-tions, such as oxidative phosphorylation in the mitochondrial respiratory chain, phagocytosis, reac-tions of biotransformation of exogenous and endogenous substrate in endoplasmic reticulum, eico-sanoid synthesis, and redox reactions in the presence of metal with variable valence. Among medici-nal plants, there is growing interest in Crocus Sativus L. It is a perennial, stemless herb, belonging to Iridaceae family, cultivated in various countries such as Greece, Italy, Spain, Israel, Morocco, Tur-key, Iran, India, China, Egypt and Mexico.

Objective:

The present study aims to address the anti-toxicant role of Crocus Sativus L. in the case of cardiovascular disease and its role towards the cardioprotective role of Crocus Sativus L.

Materials and

Methods:

An electronic literature search was conducted by the two authors from 1993 to August 2017. Original articles and systematic reviews (with or without meta-analysis), as well as case reports were selected. Titles and abstracts of papers were screened by a third reviewer to deter-mine whether they met the eligibility criteria, and full texts of the selected articles were retrieved.

Results:

Our review has indicated that scientific literature confirms the role of Crocus Sativus L. as a cardiovascular-protective agent. The literature review showed that Saffron is a potent cardiovascular-protective agent with a plethora of applications ranging from ischemia-reperfusion injury, diabetes and hypertension to hyperlipidemia.

Conclusion:

Literature findings represented in current review herald promising results for using Crocus Sativus L. and/or its active constituents as a cardiovascular-protective agent and in particular, Crocus Sativus L. manifests beneficial results against ischemia-reperfusion injury, hypertension, hy-perlipidemia and diabetes

The effect of zinc acexamate on oxidative stress, inflammation and mitochondria induced apoptosis in rat model of renal warm ischemia

AIM

Zinc has proved its efficacy in many models of ischemia reperfusion (I/R) injury. In this study, we used zinc acexamate (ZAC) as an exogenous source of zinc against renal I/R injury and we investigated whether its protective effects are mediated by the decrease of oxidative stress, inflammation, and mitochondria induced-apoptosis.

METHODS

Rats were orally pretreated with vehicle or ZAC (10 or 100 mg/kg) 24 h and 30 min prior to 1 h of bilateral renal warm ischemia and 2 h of reperfusion.

RESULTS

Our data showed that 10 mg/kg of ZAC, but not 100 mg/kg, improved renal architecture and function. Also, the low dose of ZAC up-regulated antioxidant enzymes activities and glutathione level and decreased lipids and proteins oxidation. Interestingly, the use of ZAC resulted in a significant reduce of pro-inflammatory cytokines (IL-1ß, IL-6 and MCP-1), enhanced mitochondria integrity and decreased expression of the pro-apoptotic protein caspase-9.

CONCLUSION

We conclude that renal I/R induced oxidative stress, inflammation and apoptosis and that the use of ZAC at 10 mg/kg, but not 100 mg/kg, protects rat kidneys from I/R injury by down-regulating these processes.

Renoprotective approaches and strategies in acute kidney injury

Acute kidney injury (AKI) is a major renal disease associated with high mortality rate and increasing prevalence. Decades of research have suggested numerous chemical and biological agents with beneficial effects in AKI. In addition, cell therapy and molecular targeting have been explored for reducing kidney tissue damage and promoting kidney repair or recovery from AKI. Mechanistically, these approaches may mitigate oxidative stress, inflammation, cell death, and mitochondrial and other organellar damage, or activate cytoprotective mechanisms such as autophagy and pro-survival factors. However, none of these findings has been successfully translated into clinical treatment of AKI. In this review, we analyze these findings and propose experimental strategies for the identification of renoprotective agents or methods with clinical potential. Moreover, we propose the consideration of combination therapy by targeting multiple targets in AKI.

The Protective Effect of γ-aminobutyric Acid on Kidney Injury Induced by Renal Ischemia-reperfusion in Ovariectomized Estradiol-treated Rats

Background:

Renal ischemia-reperfusion injury (IRI) is one of the most important causes of kidney injury, which is possibly gender-related. This study was designed to investigate the role of γ-aminobutyric acid (GABA) against IRI in ovariectomized estradiol-treated rats.

Methods:

Thirty-five ovariectomized Wistar rats were used in six experimental groups. The first three groups did not subject to estradiol treatment and assigned as sham-operated, control, and GABA-treated groups. GABA (50 μmol/kg) and saline were injected in the treated and control groups 30 min before the surgery, respectively. The second three groups received the same treatments but received estradiol valerate (500 μg/kg, intramuscularly) 3 days prior to the surgery. The IRI was induced in the control and treated groups by clamping the renal artery for 45 min and then 24 h of reperfusion. All animals were sacrificed for the measurements.

Results:

The serum levels of creatinine and blood urea nitrogen, kidney weight, and kidney tissue damage score significantly increased in the IRI rats (P < 0.05). GABA significantly decreased the aforementioned parameters (P < 0.05). The uterus weight increased significantly in rats that received estradiol (P < 0.05). Serum and kidney levels of nitrite (nitric oxide metabolite) did not alter significantly. Serum level of malondialdehyde increased significantly in the ovariectomized rats exposed to IRI (P < 0.05).

Conclusions:

It seems that GABA improved IRI in ovariectomized rats. Estradiol was also nephroprotective against IRI. However, co-administration of estradiol and GABA could not protect the kidney against IRI.

Ascorbic acid improves renal microcirculatory oxygenation in a rat model of renal I/R injury

Background and objectives

Acute kidney injury (AKI) is a clinical condition associated with a degree of morbidity and mortality despite supportive care, and ischemia/reperfusion injury (I/R) is one of the main causes of AKI. The pathophysiology of I/R injury is a complex cascade of events including the release of free oxygen radicals followed by damage to proteins, lipids, mitochondria, and deranged tissue oxygenation. In this study, we investigated whether the antioxidant ascorbic acid would be able to largely prevent oxidative stress and consequently, reduce I/R-related injury to the kidneys in terms of oxygenation, inflammation, and renal failure.

Materials and methods

Rats were divided into three groups (n = 6/group): (1) a time control group; (2) a group subjected to renal ischemia for 60 min by high aortic occlusion followed by 2 h of reperfusion (I/R); and (3) a group subjected to I/R and treated with an i.v. 100 mg/kg bolus ascorbic acid 15 min before ischemia and continuous infusion of 50 mg/kg/hour for 2 h during reperfusion (I/R + AA). We measured renal tissue oxidative stress, microvascular oxygenation, renal oxygen delivery and consumption, and renal expression of inflammatory and injury markers.

Results

We demonstrated that aortic clamping and release resulted in increased oxidative stress and inflammation that was associated with a significant fall in systemic and renal hemodynamics and oxygenation parameters. The treatment of ascorbic acid completely abrogated oxidative stress and inflammatory parameters. However, it only partly improved microcirculatory oxygenation and was without any effect on anuria.

Conclusion

The ascorbic acid treatment partly improves microcirculatory oxygenation and prevents oxidative stress without restoring urine output in a severe I/R model of AKI.

Synergistic effects of leflunomide and benazepril in streptozotocin-induced diabetic nephropathy

BACKGROUND

Leflunomide (LEF) and benazepril have renoprotective effects on diabetic nephropathy (DN) through their anti-inflammatory and anti-fibrotic activities. This study investigated whether combined treatment using LEF and benazepril affords superior protection compared with the respective monotherapies.

METHODS

Diabetes was induced with streptozotocin (STZ, 65 mg/kg) by intraperitoneal injection in male Wistar rats. Two weeks after STZ injection, diabetic rats were treated daily for 12 weeks with LEF (10 mg/kg), benazepril (10 mg/kg), or a combination of both. Basic parameters (body weight, fasting blood glucose level, and 24 h urinary protein excretion), histopathology, inflammatory [inflammatory cell infiltration (ED-1), monocyte chemoattractant protein-1 (MCP-1), and Toll-like receptor-2 (TLR-2)] and glomerulosclerotic factors [transforming growth factor-β1 (TGF-β1) and connective tissue growth factor (CTGF)], and oxidative stress (8-hydroxy-2'-deoxyguanosine, 8-OHdG) were studied.

RESULTS

Benazepril or LEF treatment significantly prevented body weight loss and 24 h urinary protein excretion induced by diabetes; combined treatment with LEF and benazepril further improved these parameters compared with giving each drug alone (all p < 0.01). Increased expression of inflammatory (MCP-1 and TLR-2) and glomerulosclerotic (TGF-β1 and CTGF) factors in diabetic rat kidney was reduced by treatment with either LEF or benazepril and was further reduced by the combined administration of the two drugs (p < 0.01). These effects were accompanied by suppression of urinary 8-OHdG excretion. There was no significant between-group difference in blood glucose level.

CONCLUSIONS

LEF treatment lessens DN, and combined treatment with LEF and benazepril provides synergistic effects in preventing DN.

Aryl hydrocarbon receptor agonist, leflunomide, protects the ischemic-reperfused kidney: role of Tregs and stem cells

The aryl hydrocarbon receptor (AHR) has emerged as a major modulator of inflammatory processes. We tested the hypothesis that AHR activation protects the ischemic-reperfused kidney in association with the suppression of the inflammatory response. Accordingly, male mice were treated with the nondioxin AHR agonist, leflunomide (40 mg/kg ip); vehicle-treated animals served as controls. Thereafter, the right kidney was subjected to an ischemia (45 min)-reperfusion (4 h) insult, while the left kidney served as a sham control. Renal cells prepared from ischemic-reperfused kidneys of leflunomide-treated mice displayed preservation of mitochondrial membrane potential (Ψ(m)) and decreased apoptosis and necrosis compared with vehicle-treated ischemic-reperfused kidneys. Leflunomide treatment increased regulatory T cells (Tregs; forkhead box P3+) and IL-10-positive cells but reduced IL-17- and IL-23-expressing cells in both the peripheral blood and kidney cells, indicative of down-regulation of inflammatory responses. Leflunomide treatment also increased mobilization of stems cells subsets (i.e., mesenchymal and hematopoietic stem cells and endothelial progenitor cells) in the peripheral blood and promoted their recruitment into the ischemic-reperfused kidney. Collectively, the results indicate that AHR stimulation may represent a novel renoprotective mechanism likely involving mobilization and recruitment of Tregs and stem cells into the damaged kidney.

Protective effects of phosphodiesterase-4-specific inhibitor rolipram on acute ischemia-reperfusion injury in rat kidney

OBJECTIVE

To investigate the effect of Rolipram, a phosphodiesterase-4-inhibitor, on renal ischemia-reperfusion injury (IRI) in rats.

METHODS

Thirty rats were divided into 5 different groups of 6 rats. Nothing was done to the control group. In the second group, the renal pedicle was clamped for 30 minutes. In the third group, 1 mg/kg of Rolipram was given by intraperitoneal injection 30 minutes before clamping. The fourth group received the same injection when the clamp was placed, as did the fifth group 30 minutes after the clamp was opened. Clamping time was set at 30 minutes. Twenty-four hours later, nephrectomy was performed in all the groups. Half of each kidney was examined histopathologically. Levels of biochemical agents, such as malondialdehyde, superoxide dismutase, and catalase, were measured in the other half.

RESULTS

The malondialdehyde (MDA) levels significantly decreased and reached control levels in the group in which Rolipram was administered 30 minutes after reperfusion (P = .07). The catalase and superoxide dismutase activities obtained from renal homogentisates of the ischemia groups were evaluated; there were striking increases in tissue levels of these 2 enzymes in the groups in which Rolipram was administered during ischemia and 30 minutes after ischemia (P < .001). Histopathologically, there was no significant difference in inflammation between the Rolipram-administrated groups compared with group 1 (control) and group 2 (IRI). Tubular necrosis and apoptosis was significantly lower in group 5 than the other groups, except group 1 (P < .001).

CONCLUSION

We suggest that in surgical procedures that can lead to renal IRI, the administration of Rolipram can decrease oxidative renal tissue damage and the severe deterioration of renal function.

Grape seed proanthocyanidin extract reduces renal ischemia/reperfusion injuries in rats

Activation of reactive oxygen species and inflammation are implicated in renal ischemia/reperfusion (I/R) injuries. This study investigated whether grape seed proanthocyanidin extract (GSPE) protects against renal I/R injury by its effect on reactive oxygen species and the inflammation pathway. Wistar rats were administered GSPE before renal ischemia, followed by reperfusion for 24 hours. Plasma concentrations of urea, creatinine and cystatin C were measured for renal dysfunction. Serum and tissue superoxide dismutase activity and glutathione peroxidase and malondialdehyde levels were measured. Renal sections were analyzed for histological grading of renal injury, and nuclear factor-ĸB activity was determined. GSPE significantly reduced increases in urea, creatinine and cystatin C; increased kidney superoxide dismutase activity and glutathione peroxidase levels and reduced malondialdehyde levels. GSPE reduced histological renal damage and nuclear factor-ĸB activity. These results suggest that GSPE reduces renal dysfunction and injury caused by renal I/R.

Effect of glutamine on the total antioxidant system of rats subjected to renal ischemia and reperfusion

PURPOSE: To evaluate the protective effects of glutamine administered before renal ischemia-reperfusion on plasma antioxidant protection, and lung and renal tissue injury. METHODS: 33 rats underwent right nephrectomy. On the eighth postoperative day, animals were randomized into three groups (n=11): glutamine, control and sham. Each group of animals received, by gavage, a particular diet for 7 days. On day 14 following nephrectomy, the animals were subjected to left renal ischemia-reperfusion. After this, blood samples were collected and the animals were killed. At necropsy the kidney and lung were removed for histology. RESULTS: The levels of total antioxidant capacity were higher in the glutamine group and control group compared with the sham group. The levels of glutathione peroxidase in both the sham and glutamine groups were higher when compared with the control group (p<0.05). The level of superoxide dismutase in the sham group was clearly higher than that in the glutamine and control groups. Histological examination showed no differences between the three groups. CONCLUSION: Prior intake of glutamine improves total antioxidant capacity and increases glutathione peroxidase levels in rats subjected to renal ischemia-reperfusion.

Ozonated autohemotherapy: protection of kidneys from ischemia in rats subjected to unilateral nephrectomy

Background

Ozonated autohemotherapy (OA) has been previously successfully used in the treatment of patients affected by peripheral occlusive arterial disease. OA consists of an intrafemoral reinfusion of autologous blood previously exposed to a mixture of oxygen/ozone (O₂/O₃). This study analyzes the effects of OA in protecting rat kidney from ischemia and ischemia/reperfusion damage.

Methods

We performed OA 30 min before the induction of 60 min renal ischemia or at the induction of 60 min postischemic reperfusion in rats subjected to unilateral nephrectomy. In addition, to evidence the possible protection induced by O₂/O₃ on endothelial functions, the present study analyzes the in vitro effects of O₂/O₃ on oxygen consumption by human umbilical vein endothelial cells (HUVEC).

Results

1) OA preserves rat kidney functions and architecture, as demonstrated by the improved levels of serum creatinine and blood urea nitrogen and by histology; 2) such protection does not correlate with the increase of plasmatic nitric oxide, but is compatible with a focal renal increase of renal βNADPH-diaphorase; 3) treatment of HUVEC with O₂/O₃ significantly increases both the rate of oxygen consumption and the mitochondrial activity assessed by confocal microscopy.

Conclusion

The preservation of the mitochondrial activity of endothelium could in vivo limit the endothelial dysfunction provoked by the Isc or Isc/R processes.

Effect of captopril treatment on recuperation from ischemia/reperfusion-induced acute renal injury

BACKGROUND

Ischemia/reperfusion triggers acute kidney injury (AKI), mainly via aggravating hypoxia, oxidative stress, inflammation and renin-angiotensin system (RAS) activation. We investigated the role of angiotensin-converting enzyme (ACE) inhibition on the progression of AKI in a rat model of ischemia/reperfusion.

METHODS

Ninety-nine Sprague-Dawley rats were subjected to 1 h ischemia/reperfusion and/or left unilateral nephrectomy, with concurrent intraperitoneal implantation of Alzet pump. Via this pump, they were continuously infused with captopril 0.5 mg/kg/day, captopril 2 mg/kg/day or saline. The rats were sacrificed following 24, 48 or 168 h. Blood samples, 24-h urine collections and kidneys were allocated, to evaluate renal function, angiotensin-II, nitric oxide (NO), apoptosis, hypoxia, oxidative stress and inflammation.

RESULTS

Serum creatinine and cystatin-C significantly increased in ischemic rats, coinciding with histopathologic intrarenal damage, decreased NO, augmented angiotensin-II, interleukin (IL)-6, IL-10, transforming growth factor-beta. At the acute reperfusion stage, captopril prevented excessive angiotensin-II synthesis, ameliorated renal dysfunction, inhibited intrarenal inflammation and improved histopathologic findings. Most of the renoprotective effects of captopril were limited predominantly to acute reperfusion stage. Concurrently, captopril significantly decreased NO availability, exacerbated intrarenal hypoxia and augmented oxidative stress.

CONCLUSIONS

At the acute stage of renal ischemia/reperfusion-induced AKI, ACE inhibition substantially contributed to the amelioration of acute injury by improving renal function, inhibiting systemic and intrarenal angiotensin-II, attenuating intrarenal inflammation and preserving renal tissue structure. Later on, at the post-reperfusion stage, most of the beneficial effects of captopril administration on the recuperating post-ischemic kidney were no longer evident. Concurrently, ACE inhibition exacerbated intrarenal hypoxia and accelerated oxidative stress, indicating that renal adaptation to some consequences of ischemia does require bioavailability of RAS components.

Attenuation of renal ischemia and reperfusion injury by human adrenomedullin and its binding protein

BACKGROUND

Acute renal failure secondary to ischemia and reperfusion (I/R) injury poses a significant burden on both surgeons and patients. It carries a high morbidity and mortality rate and no specific treatment currently exists. Major causes of renal I/R injury include trauma, sepsis, hypoperfusion, and various surgical procedures. We have demonstrated that adrenomedullin (AM), a novel vasoactive peptide, combined with AM binding protein-1 (AMBP-1), which augments the activity of AM, is beneficial in various disease conditions. However, it remains unknown whether human AM/AMBP-1 provides any beneficial effects in renal I/R injury. The objective of our study therefore was to determine whether administration of human AM/AMBP-1 can prevent and/or minimize damage in a rat model of renal I/R injury.

METHODS

Male adult rats were subjected to renal I/R injury by bilateral renal pedicle clamping with microvascular clips for 60 min followed by reperfusion. Human AM (12 microg/kg BW) and human AMBP-1 (40 microg/kg BW) or vehicle (52 microg/kg BW human albumin) were given intravenously over 30 min immediately following the clip removal (i.e., reperfusion). Rats were allowed to recover for 24 h post-treatment, and blood and renal tissue samples were collected. Plasma levels of AM were measured using a radioimmunoassay specific for rat AM. Plasma AMBP-1 was measured by Western analysis. Renal water content and serum levels of systemic markers of tissue injury were measured. Serum and renal TNF-alpha levels were also assessed.

RESULTS

At 24 h after renal I/R injury, plasma levels of AM were significantly increased while plasma AMBP-1 was markedly decreased. Renal water content and systemic markers of tissue injury (e.g., creatinine, BUN, AST, and ALT) were significantly increased following renal I/R injury. Serum and renal TNF-alpha levels were also increased post injury. Administration of human AM/AMBP-1 decreased renal water content, and plasma levels of creatinine, BUN, AST, and ALT. Serum and renal TNF-alpha levels were also significantly decreased after AM/AMBP-1 treatment.

CONCLUSION

Treatment with human AM/AMBP-1 in renal I/R injury significantly attenuated organ injury and the inflammatory response. Thus, human AM combined with human AMBP-1 may be developed as a novel treatment for patients with acute renal I/R injury.

Protective effects of leflunomide on intestinal ischemia-reperfusion injury: leflunomide against intestinal ischemia-reperfusion

AIM

The aim of this study was to investigate the possible protective effects of leflunomide, which has antioxidant and anti-inflammatory properties, against intestinal IR injury in rats.

MATERIALS AND METHODS

Forty female Wistar albino rats were divided into six groups: control (n = 5), drug control (n = 7), sham operated (n = 7), IR alone (n = 7), IR plus vehicle (IR + vehicle, n = 7) and IR plus 20 mg/kg leflunomide (IR + Leflunomide, n = 7). While rats were pretreated intragastrically with leflunomide (20 mg/kg) and vehicle in three doses prior to the experiment, respectively, in the IR + Leflunomide and IR + vehicle groups, no additional application was done in the IR alone group. Intestines were exteriorized, and the superior mesenteric artery was occluded for 45 min ischemia, and then the clamp was removed for 120 min reperfusion. After the experiment, the intestines were removed for biochemical and histological examinations. Additionally, blood samples were taken for measurements of antioxidant parameters.

RESULTS

The intestinal IR significantly increased the MDA level and MPO activity; however, treatment with leflunomide reversed those findings (P < 0.05). The CAT activity of the IR + Leflunomide group was significantly higher than in the IR groups (P < 0.05). The SOD activity was increased in the intestinal IR group, and leflunomide treatment reversed that, too (P <0.05). The light microscopic findings showed that IR caused mucosal necrosis and leflunomide treatment reduced the morphological alterations associated with IR (P < 0.05).

CONCLUSION

Intestinal IR injury may be reversed by the anti-inflammatory and antioxidant actions of leflunomide.

The protective effects of ascorbic acid against renal ischemia-reperfusion injury in male rats

There is increasing evidence to suggest that toxic oxygen radicals play an essential role in the pathogenesis of ischemia/reperfusion (I/R) injury in the kidney. This study was designed to investigate the effects of ascorbic acid (AA) in I/R-induced renal injury in rats. Thirty two male Sprague-Dawley rats were divided equally into four groups: group 1 (control; dissection of the right renal pedicle without nephrectomy), group 2 (sham operated; unilateral nephrectomy), group 3 (I/R; unilateral nephrectomy + I/R); and group 4 (AA+I/R; unilateral nephrectomy and I/R treated with ascorbic acid, 250mg kg(-1) i.p., for one hour prior to ischemia). On the 15th day following nephrectomy, groups 3 and 4 were subjected to 45 min of renal pedicle occlusion followed by 3 h of reperfusion. At the end of the treatment period, kidney samples were taken for histological examination or determination of the renal malondialdehyde (MDA) and glutathione (GSH) levels. Serum creatinine, blood urea nitrogen (BUN), and lactate dehydrogenase (LDH) concentrations were measured for the evaluation of renal function. I/R caused a significant decrease in GSH level, which was accompanied with a significant increase in MDA level of kidney tissues. Similarly, serum BUN and creatinine levels, as well as LDH, were elevated in the I/R group as compared to the control group. In group four, AA treatment reversed all the changes in these biochemical indices, as well as histopathological alterations normally induced by I/R. The findings imply that reactive oxygen species play a causal role in I/R-induced renal injury, and that AA exerts renoprotective effects, probably by radical scavenging and antioxidant activities.

Protective effect of rutin on the ischemia/reperfusion induced damage in rat kidney

Reactive oxygen species (ROS) are suggested to participate in ischemia/reperfusion (I/R) injury in the kidney. This study was designed to investigate the effect of rutin, a bioflavonoid, in I/R induced renal injury. Wistar albino rats were unilaterally nephrectomized, and 2 wk later they were subjected to 45 min of left renal pedicle occlusion followed by 3h of reperfusion. Either rutin (1g/kg) or saline was administrated (i.p.) 1h prior to ischemia. At the end of the reperfusion period, kidney samples were taken for determination of renal malondialdehyde (MDA) and glutathione (GSH) levels, manganese-superoxide dismutase (MnSOD) activity and histological examination. Serum creatinine, blood urea nitrogen (BUN), and lactate dehydrogenase (LDH) concentrations were measured for the evaluation of renal function. I/R caused a significant decrease in GSH level and MnSOD activity, which was accompanied by a significant increase in MDA level of kidney tissues. Similarly, serum BUN and creatinine levels, as well as LDH were elevated in the I/R group compared with the control group. Pretreatment of rats with rutin (1g/kg/ i.p.) significantly attenuated renal dysfunction, reduced elevated MDA levels, and restored the depleted MnSOD activity and GSH levels. These beneficial changes in the biochemical parameters were also associated with parallel changes in histopathological appearance. These findings suggest that ROS play a causal role in I/R induced renal injury, and that rutin exerts renal-protective effects, probably by inhibiting ROS and antioxidant activities.

Novel pharmacological approaches to the treatment of renal ischemia-reperfusion injury: a comprehensive review

Renal ischemia-reperfusion (I-R) contributes to the development of ischemic acute renal failure (ARF). Multi-factorial processes are involved in the development and progression of renal I-R injury with the generation of reactive oxygen species, nitric oxide and peroxynitrite, and the decline of antioxidant protection playing major roles, leading to dysfunction, injury, and death of the cells of the kidney. Renal inflammation, involving cytokine/adhesion molecule cascades with recruitment, activation, and diapedesis of circulating leukocytes is also implicated. Clinically, renal I-R occurs in a variety of medical and surgical settings and is responsible for the development of acute tubular necrosis (a characteristic feature of ischemic ARF), e.g., in renal transplantation where I-R of the kidney directly influences graft and patient survival. The cellular mechanisms involved in the development of renal I-R injury have been targeted by several pharmacological interventions. However, although showing promise in experimental models of renal I-R injury and ischemic ARF, they have not proved successful in the clinical setting (e.g., atrial natriuretic peptide, low-dose dopamine). This review highlights recent pharmacological developments, which have shown particular promise against experimental renal I-R injury and ischemic ARF, including novel antioxidants and antioxidant enzyme mimetics, nitric oxide and nitric oxide synthase inhibitors, erythropoietin, peroxisome-proliferator-activated receptor agonists, inhibitors of poly(ADP-ribose) polymerase, carbon monoxide-releasing molecules, statins, and adenosine. Novel approaches such as recent research involving combination therapies and the potential of non-pharmacological strategies are also considered.