GW274150, a potent and highly selective inhibitor of iNOS, reduces experimental renal ischemia/reperfusion injury

Metabolic Adaptations and Functional Activity of Macrophages in Homeostasis and Inflammation

In recent years, the role of cellular metabolism in immunity has come into the focus of many studies. These processes form a basis for the maintenance of tissue integrity and homeostasis, as well as represent an integral part of the immune response, in particular, inflammation. Metabolic adaptations not only ensure energy supply for immune response, but also affect the functions of immune cells by controlling transcriptional and post-transcriptional programs. Studying the immune cell metabolism facilitates the search for new treatment approaches, especially for metabolic disorders. Macrophages, innate immune cells, are characterized by a high functional plasticity and play a key role in homeostasis and inflammation. Depending on the phenotype and origin, they can either perform various regulatory functions or promote inflammation state, thus exacerbating the pathological condition. Furthermore, their adaptations to the tissue-specific microenvironment influence the intensity and type of immune response. The review examines the effect of metabolic reprogramming in macrophages on the functional activity of these cells and their polarization. The role of immunometabolic adaptations of myeloid cells in tissue homeostasis and in various pathological processes in the context of inflammatory and metabolic diseases is specifically discussed. Finally, modulation of the macrophage metabolism-related mechanisms reviewed as a potential therapeutic approach.

Hydrogen Sulfide-Releasing Indomethacin-Derivative (ATB-344) Prevents the Development of Oxidative Gastric Mucosal Injuries

Hydrogen sulfide (H2S) emerged recently as an anti-oxidative signaling molecule that contributes to gastrointestinal (GI) mucosal defense and repair. Indomethacin belongs to the class of non-steroidal anti-inflammatory drugs (NSAIDs) and is used as an effective intervention in the treatment of gout- or osteoarthritis-related inflammation. However, its clinical use is strongly limited since indomethacin inhibits gastric mucosal prostaglandin (PG) biosynthesis, predisposing to or even inducing ulcerogenesis. The H2S moiety was shown to decrease the GI toxicity of some NSAIDs. However, the GI safety and anti-oxidative effect of a novel H2S-releasing indomethacin derivative (ATB-344) remain unexplored. Thus, we aimed here to compare the impact of ATB-344 and classic indomethacin on gastric mucosal integrity and their ability to counteract the development of oxidative gastric mucosal injuries. Wistar rats were pretreated intragastrically (i.g.) with vehicle, ATB-344 (7-28 mg/kg i.g.), or indomethacin (5-20 mg/kg i.g.). Next, animals were exposed to microsurgical gastric ischemia-reperfusion (I/R). Gastric damage was assessed micro- and macroscopically. The volatile H2S level was assessed in the gastric mucosa using the modified methylene blue method. Serum and gastric mucosal PGE2 and 8-hydroxyguanozine (8-OHG) concentrations were evaluated by ELISA. Molecular alterations for gastric mucosal barrier-specific targets such as cyclooxygenase-1 (COX)-1, COX-2, heme oxygenase-1 (HMOX)-1, HMOX-2, superoxide dismutase-1 (SOD)-1, SOD-2, hypoxia inducible factor (HIF)-1α, xanthine oxidase (XDH), suppressor of cytokine signaling 3 (SOCS3), CCAAT enhancer binding protein (C/EBP), annexin A1 (ANXA1), interleukin 1 beta (IL-1β), interleukin 1 receptor type I (IL-1R1), interleukin 1 receptor type II (IL-1R2), inducible nitric oxide synthase (iNOS), tumor necrosis factor receptor 2 (TNFR2), or H2S-producing enzymes, cystathionine γ-lyase (CTH), cystathionine β-synthase (CBS), or 3-mercaptopyruvate sulfur transferase (MPST), were assessed at the mRNA level by real-time PCR. ATB-344 (7 mg/kg i.g.) reduced the area of gastric I/R injuries in contrast to an equimolar dose of indomethacin. ATB-344 increased gastric H2S production, did not affect gastric mucosal PGE2 content, prevented RNA oxidation, and maintained or enhanced the expression of oxidation-sensitive HMOX-1 and SOD-2 in line with decreased IL-1β and XDH. We conclude that due to the H2S-releasing ability, i.g., treatment with ATB-344 not only exerts dose-dependent GI safety but even enhances gastric mucosal barrier capacity to counteract acute oxidative injury development when applied at a low dose of 7 mg/kg, in contrast to classic indomethacin. ATB-344 (7 mg/kg) inhibited COX activity on a systemic level but did not affect cytoprotective PGE2 content in the gastric mucosa and, as a result, evoked gastroprotection against oxidative damage.

Amazonia Phytotherapy Reduces Ischemia and Reperfusion Injury in the Kidneys

Acute kidney injury (AKI) is defined as a sudden decrease in kidney function. Phytomedicines have shown positive effects in the treatment of AKI worldwide. The aim of this study was to evaluate the effect of Abuta grandifolia on the renal function of rats submitted to AKI. A phytochemical study of the plant was performed through liquid chromatography coupled with mass spectrometry (CL-EM) and DPPH and ABTS antioxidant tests. Renal function tests were performed in 20 male adult Wistar rats weighing from 250 to 300 g distributed in the following groups: SHAM (submitted to laparotomy with simulation of renal ischemia); ABUTA (animals that received 400 mg/kg of AG, orally-VO, once a day, for 5 days, with simulation of renal ischemia); I/N (animals submitted to laparotomy for clamping of bilateral renal pedicles for 30 min, followed by reperfusion); ABUTA + I/R (animals that received AG-400 mg/kg, 1× per day, VO, for 5 days, submitted to renal ischemia after treatment with herbal medicine). The results suggest that the consumption of Abuta grandifolia promoted renoprotection, preventing the reduction of renal function induced by ischemia, oxidizing activity, and deleterious effects on the renal tissue, confirmed by the decrease of oxidative metabolites and increase of antioxidants in the animals' organisms.

A novel beneficial role of humanin on intestinal apoptosis and dysmotility in a rat model of ischemia reperfusion injury

A prevalent clinical problem including sepsis, shock, necrotizing enterocolitis, and mesenteric thrombosis is intestinal ischemia/reperfusion (I/R) injury. Humanin (HN), a recently identified mitochondrial polypeptide, exhibits antioxidative and antiapoptotic properties. This work aimed to study the role of HN in a model of experimental intestinal I/R injury and its effect on associated dysmotility. A total of 36 male adult albino rats were allocated into 3 equal groups. Sham group: merely a laparotomy was done. I/R group: for 1 h, clamping of the superior mesenteric artery was done, and then reperfusion was allowed for 2 h later. HN-I/R group: rats underwent ischemia and reperfusion, and 30 min before the reperfusion, they received an intraperitoneal injection of 252 μg/kg of HN. Small intestinal motility was evaluated, and jejunal samples were got for biochemical and histological analysis. I/R group showed elevation of intestinal NO, MDA, TNF- α, and IL-6 and decline of GPx and SOD levels. Furthermore, histologically, there were destructed jejunal villi especially their tips and increased tissue expression of caspase-3 and i-NOS, in addition to reduced small intestinal motility. Compared to I/R group, HN-I/R group exhibited decrease intestinal levels of NO, MDA, TNF- α, and IL-6 and increase GPx and SOD. Moreover, there was noticeable improvement of the histopathologic features and decreased caspase-3 and iNOS immunoreactivity, beside enhanced small intestinal motility. HN alleviates inflammation, apoptosis, and intestinal dysmotility encouraged by I/R. Additionally, I/R-induced apoptosis and motility alterations depend partly on the production of nitric oxide.

Antioxidant and Anti-inflammatory Activity of Sea Cucumber (Holothuria scabra) Active Compounds against KEAP1 and iNOS Protein

Oxidative stress and inflammation have a role in the development of various diseases. Oxidative stress and inflammation are associated with many proteins, including Kelch ECH associating protein 1 (KEAP1) and inducible nitric oxide synthase (iNOS) proteins. The active compounds contained in Holothuria scabra have antioxidant and anti-inflammatory properties. This study aimed to evaluate the antioxidant and anti-inflammatory activity of sea cucumber's active compounds by targeting KEAP1 and iNOS proteins. 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and nitric oxide (NO) scavenging activity of H. scabra extract were measured spectrophotometrically. The 3-dimensional (3D) structures of sea cucumber's active compounds and proteins were obtained from the PubChem and Research Collaboratory for Structural Bioinformatics Protein Data Bank (RCSB PDB) databases. Molecular docking was performed using AutoDock Vina software. Molecular dynamics simulations were carried out using Yet Another Scientific Artificial Reality Application (YASARA) software with environmental parameters according to the cell's physiological conditions. The membrane permeability test was performed using the PerMM web server. The methanol extract of H. scabra had a weak antioxidant activity against DPPH and strong activity against NO radical. Scabraside and holothurinoside G had the most negative binding affinity values when interacting with the active site of KEAP1 and iNOS proteins. Molecular dynamics simulations also showed that both compounds were stable when interacting with KEAP1 and iNOS. However, scabraside and holothurinoside G were difficult to penetrate the cell plasma membrane, which is seen from the high energy transfer value in the lipid acyl chain region of phospholipids. Scabraside and holothurinoside G are predicted to act as antioxidants and anti-inflammations, but in their implementation to in vitro and in vivo study, it is necessary to have liposomes or nanoparticles, or other delivery methods to help these 2 compounds enter the cell.

View of the Renin-Angiotensin System in Acute Kidney Injury Induced by Renal Ischemia-Reperfusion Injury

Renal ischemia-reperfusion injury (RIRI) is a sequence of complicated events that is defined as a reduction of the blood supply followed by reperfusion. RIRI is the leading cause of acute kidney injury (AKI). Among the diverse mediators that take part in RIRI-induced AKI, the renin-angiotensin system (RAS) plays an important role via conventional (angiotensinogen, renin, angiotensin-converting enzyme (ACE), angiotensin (Ang) II, and Ang II type 1 receptor (AT1R)) and nonconventional (ACE2, Ang 1-7, Ang 1-9, AT2 receptor (AT2R), and Mas receptor (MasR)) axes. RIRI alters the balance of both axes so that RAS can affect RIRI-induced AKI. In overall, the alteration of Ang II/AT1R and AKI by RIRI is important to consider. This review has looked for the effects and interactions of RAS activities during RIRI conditions.

Renal Nano-drug delivery for acute kidney Injury: Current status and future perspectives

Acute kidney injury (AKI) causes considerable morbidity and mortality, particularly in the case of post-cardiac infarction or kidney transplantation; however, the site-specific accumulation of small molecule reno-protective agents for AKI has often proved ineffective due to dynamic fluid and solute excretion and non-selectivity, which impedes therapeutic efficacy. This article reviews the current status and future trajectories of renal nanomedicine research for AKI management from pharmacological and clinical perspectives, with a particular focus on appraising nanosized drug carrier (NDC) use for the delivery of reno-protective agents of different pharmacological classes and the effectiveness of NDCs in improving renal tissue targeting selectivity and efficacy of said agents. This review reveals the critical shift in the role of the small molecule reno-protective agents in AKI pharmacotherapy - from prophylaxis to treatment - when using NDCs for delivery to the kidney. We also highlight the need to identify the accumulation sites of NDCs carrying reno-protective agents in renal tissues during in vivo assessments and detail the less-explored pharmacological classes of reno-protective agents whose efficacies may be improved via NDC-based delivery. We conclude the paper by outlining the challenges and future perspectives of NDC-based reno-protective agent delivery for better clinical management of AKI.

Curcumin Protects against Renal Ischemia/Reperfusion Injury by Regulating Oxidative Stress and Inflammatory Response

Objective

The aim of this study was to explore the pharmacological effects of curcumin on oxidative stress and inflammatory response of renal dysfunction induced by renal ischemia/reperfusion (RIRI).

Methods

Fifty male SD rats (Sprague Dawley) were randomly divided into the sham group, RIRI group, and curcumin group (low, medium, and high). The RIRI model was established by clipping the left renal artery for 45 min and then reperfusion for 24 h and resection of the contralateral kidney. In the curcumin group, curcumin was intraperitoneally injected once a day for 3 consecutive days using different dosage regimens. The RIRI group was intraperitoneally administered with normal saline. Renal injury was evaluated by measuring the concentration of creatinine (Cr) and urea nitrogen (BUN) in serum. Oxidative stress was assessed by assessing the level of malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione (GSH), and iron reduction/antioxidant capacity (FRAP) in tissues. In addition, the protective effect of RIRI was investigated by measuring Paller scores, the level of serum inflammatory factors and caspase-3, and the number of apoptotic cells.

Results

Ischemia/reperfusion resulted in increased levels of Cr and BUN in serum and MDA in tissues and decreased levels of SOD, CAT, GPx, GSH, and FRAP. Curcumin pretreatment strikingly increased the level of SOD, CAT, GPx, GSH, IL-10, IFN-γ, and FRAP and significantly decreased MDA, Cr, BUN, IL-8, TNF-α, IL-6, and myeloperoxidase (MPO) expressions in tissues.

Conclusion

Curcumin can relieve the degree of renal injury and improve renal function in ischemia-reperfusion, which may be related to the fact that curcumin can increase SOD content in serum and reduce MDA and FRAP levels in the rat model.

Subacute cadmium exposure promotes M1 macrophage polarization through oxidative stress-evoked inflammatory response and induces porcine adrenal fibrosis

Cadmium (Cd) is a widely distributed environmental pollutant with immunotoxicity and endocrine toxicity. M1/M2 macrophages participate in the immune response and exert an essential influence on fibrosis. Nevertheless, whether Cd can induce porcineadrenal fibrosis by affecting the polarization of M1/M2 macrophages and its potential regulatory mechanism have not been explored. We added 20 mg/kg CdCl₂ to the pig diet for 40 days to investigate the fibrogenic effect of subacute Cd exposure on the adrenal gland. The results indicated that the ACTH and CORT in serum were decreased by 15.26 % and 21.99 %, respectively. The contents of adrenal mineral elements Cd, Cr, Mn were increased up to 34, 1.93, 1.42 folds and Co, Zn, Sn were reduced by 21.57 %, 20.52 %, 15.75 %. Concurrently, the pro-oxidative indicators (LPO, MDA and H₂O₂) were increased by 1.85, 2.20, 2.77 folds and 3.60, 11.15, 4.11 folds upregulated mRNA levels of TLR4, NF-κB, NLRP3 were observed. Subsequently, the expression of M1 macrophages polarization markers (IL-6, iNOS, TNF-α, CCL2 and CXCL9) were raised by 2.03, 2.30, 2.35, 1.58, 1.56 folds, while M2 macrophages (IL-4, CCL24, Arg1, IL-10, MRC1) showed a 62.34 %, 31.88 %, 50.26 %, 74.00 %, 69.34 % downregulation. The expression levels of AMPK subunits and genes related to glycolysis, oxidative phosphorylation (OXPHOS) and fatty acid oxidation (FAO) were also markedly increased. Additionally, the expression level of TGF-β1, Smad2/3 and downstream pro-fibrotic markers was obviously upregulated. Taken together, we conclude that Cd activates the oxidative stress-mediated TLR4/NF-κB/NLRP3 inflammatory signal transduction, leading to porcine adrenal fibrosis by promoting macrophage polarization toward M1.

Pharmacological or genetic inhibition of iNOS prevents cachexia-mediated muscle wasting and its associated metabolism defects

Cachexia syndrome develops in patients with diseases such as cancer and sepsis and is characterized by progressive muscle wasting. While iNOS is one of the main effectors of cachexia, its mechanism of action and whether it could be targeted for therapy remains unexplored. Here, we show that iNOS knockout mice and mice treated with the clinically tested iNOS inhibitor GW274150 are protected against muscle wasting in models of both septic and cancer cachexia. We demonstrate that iNOS triggers muscle wasting by disrupting mitochondrial content, morphology, and energy production processes such as the TCA cycle and acylcarnitine transport. Notably, iNOS inhibits oxidative phosphorylation through impairment of complexes II and IV of the electron transport chain and reduces ATP production, leading to energetic stress, activation of AMPK, suppression of mTOR, and, ultimately, muscle atrophy. Importantly, all these effects were reversed by GW274150. Therefore, our data establish how iNOS induces muscle wasting under cachectic conditions and provide a proof of principle for the repurposing of iNOS inhibitors, such as GW274150 for the treatment of cachexia.

Inducible nitric oxide synthase (iNOS) mediates ethanol-induced redox imbalance and upregulation of inflammatory cytokines in the kidney

Overexpression of the inducible isoform of the enzyme nitric oxide synthase (iNOS) has been associated to pathological processes in the kidney. Ethanol consumption induces the renal expression of iNOS; however, the contribution of this enzyme to the deleterious effects of ethanol in the kidney remains elusive. We examined whether iNOS plays a role in the renal dysfunction and oxidative stress induced by ethanol consumption. With this purpose, male C57BL/6 wild-type (WT) or iNOS-deficient (iNOS^-/-) mice were treated with ethanol (20% v/v) for 10 weeks. Treatment with ethanol increased the expression of Nox4 as well as the concentration of thiobarbituric acid reactive substances and the levels of tumor necrosis factor α in the renal cortex of WT but not iNOS^-/- mice. Augmented serum levels of creatinine and increased systolic blood pressure were found in WT and iNOS^-/- mice treated with ethanol. WT mice treated with ethanol showed increased production of reactive oxygen species and myeloperoxidase activity, but these responses were attenuated in iNOS^-/- mice. We concluded that iNOS played a role in ethanol-induced oxidative stress and pro-inflammatory cytokine production in the kidney. These are mechanisms that may contribute to the renal toxicity induced by ethanol.

Small-Molecule Inhibitors of Reactive Oxygen Species Production

Reactive oxygen species (ROS) are involved in physiological cellular processes including differentiation, proliferation, and apoptosis by acting as signaling molecules or regulators of transcription factors. The maintenance of appropriate cellular ROS levels is termed redox homeostasis, a balance between their production and neutralization. High concentrations of ROS may contribute to severe pathological events including cancer, neurodegenerative, and cardiovascular diseases. In recent years, approaches to target the sources of ROS production directly in order to develop tool compounds or potential therapeutics have been explored. Herein, we briefly outline the major sources of cellular ROS production and comprehensively review the targeting of these by small-molecule inhibitors. We critically assess the value of ROS inhibitors with different mechanisms-of-action, including their potency, mode-of-action, known off-target effects, and clinical or preclinical status, while suggesting future avenues of research in the field.

Metabolic reprogramming in macrophage responses

Macrophages are critical mediators of tissue homeostasis, with the function of tissue development and repair, but also in defense against pathogens. Tumor-associated macrophages (TAMs) are considered as the main component in the tumor microenvironment and play an important role in tumor initiation, growth, invasion, and metastasis. Recently, metabolic studies have revealeded specific metabolic pathways in macrophages are tightly associated with their phenotype and function. Generally, pro-inflammatory macrophages (M1) rely mainly on glycolysis and exhibit impairment of the tricarboxylic acid (TCA) cycle and mitochondrial oxidative phosphorylation (OXPHOS), whereas anti-inflammatory macrophages (M2) are more dependent on mitochondrial OXPHOS. However, accumulating evidence suggests that macrophage metabolism is not as simple as previously thought. This review discusses recent advances in immunometabolism and describes how metabolism determines macrophage phenotype and function. In addition, we describe the metabolic characteristics of TAMs as well as their therapeutic implications. Finally, we discuss recent obstacles facing this area as well as promising directions for future study.

MiR-302b-5p enhances the neuroprotective effect of IGF-1 in methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced Parkinson's disease by regulating inducible nitric-oxide synthase

Parkinson's disease (PD) is a neurodegenerative disease which results in damage in neuronal cells. Insulin-like growth factor (IGF)-1 was previously reported to play a role of neuroprotection in some diseases. Nitric oxide (NO) can also regulate neuronal cells. However, the mechanisms underlying IGF-1 and NO in PD still need to be elucidated. In present study, we explored the interaction between IGF-1 and inducible Nitric-Oxide Synthase (iNOS) in PD progression. We firstly constructed PD models by methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) or MPP⁺ treatment. Then RT-qPCR revealed that IGF-1 expression was downregulated while iNOS expression was upregulated in MPTP model. Moreover, IGF-1 elevation or iNOS depletion enhanced cell viability and blocked cell apoptosis. Rescue assay disclosed iNOS overexpression reversed the effect on viability and apoptosis mediated by IGF-1 upregulation. Furthermore, IGF-1 was identified to positively regulate miR-302b-5p which could target iNOS. MiR-302b-5p could abolish the inhibitory function IGF-1 exerted on cell apoptosis and iNOS could counteract miR-302b-5p upregulation-triggered inhibition on cell apoptosis as well. Besides, we observed the deficiency of miR-302b-5p improved the lesioned neurobehavior of MPTP-treated mice. To sum up, present study proved that miR-302b-5p enhanced the neuroprotective effect of IGF-1 in MPTP-induced PD by regulating iNOS, recommending a novel therapeutic target for PD treatment. SIGNIFICANCE OF THE STUDY: In this study, we mainly explored that IGF-1 was decreased while iNOS was boosted in MPTP-induced PD mice model; IGF-1 suppressed while iNOS promoted MPP⁺ -induced toxicity and apoptosis in SH-SY5Y cells; miR-302b-5p ehanhced the neuroprotective effect of IGF-1 via targeting Inos; deficiency of miR-302b-5p improved the lesioned neurobehavior of MPTP-treated mice.

Vagus Nerve Stimulation Ameliorates Renal Ischemia-Reperfusion Injury through Inhibiting NF-κB Activation and iNOS Protein Expression

OBJECTIVE

In renal ischemia/reperfusion injury (RIRI), nuclear factor κB (NF-κB (NF-κB (NF.

METHODS

Eighteen male Sprague-Dawley rats were randomly allocated into the sham group, the I/R group, and the VNS+I/R group, 6 rats per group. An RIRI model was induced by a right nephrectomy and blockade of the left renal pedicle vessels for 45 min. After 6 h of reperfusion, the blood samples and renal samples were collected. The VNS treatment was performed throughout the I/R process in the VNS+I/R group using specific parameters (20 Hz, 0.1 ms in duration, square waves) known to produce a small but reliable bradycardia. Blood was used for evaluation of renal function and inflammatory state. Renal injury was evaluated via TUNEL staining. Renal samples were harvested to evaluate renal oxidative stress, NF-κB (NF.

RESULTS

The VNS treatment reduces serum creatinine (Cr) and blood urea nitrogen (BUN) levels. Simultaneously, the levels of tumor necrosis factor alpha (TNF-α), interleukin 6 (IL-6), and interleukin 1-beta (IL-1β) were significantly increased in the I/R group, but VNS treatment markedly ameliorated this inflammatory response. Furthermore, the VNS ameliorated oxidant stress and renal injury, indicated by a decrease in 3-nitrotyrosine (3-NT) formation and MDA and MPO levels and an increase in the SOD level compared to that in the I/R group. Finally, the VNS also significantly decreases NF-κB (NF.

CONCLUSION

Our findings indicate that NF-κB activation increased iNOS expression and promoted RIRI and that VNS treatment attenuated RIRI by inhibiting iNOS expression, oxidative stress, and inflammation via NF-κB inactivation.κB (NF-κB (NF.

Protective effect of piperine in ischemia-reperfusion induced acute kidney injury through inhibition of inflammation and oxidative stress

Background and aim

Renal ischemia-reperfusion is associated with inflammation and oxidative stress. As a major compound in black pepper, piperine has anti-inflammatory and anti-oxidative properties. In present study, the protective effects of oral administration of piperine in renal ischemia-reperfusion (IR) induced acute kidney injuries (AKI) were investigated.

Experimental procedure

Male Wistar rats received piperine (10 or 20 mg/kg.bw) or vehicle for 10 days. The artery and vein of both kidneys were then clamped for 30 min, followed by a 24-h reperfusion period. Concentrations of creatinine and urea-nitrogen in descending aorta blood were measured, and malondialdehyde (MDA) and ferric reducing/antioxidant power (FRAP) levels were measured in kidney tissue to evaluate the oxidative stress. Inflammation was evaluated by measuring the TNF-α and ICAM-1 mRNA expression levels in renal cortical tissue using Real Time PCR method and counting leukocytes infiltration to interstitium. Further measured were tissue damages in H & E stained sections.

Results

Renal IR reduced FRAP, while increasing the plasma concentrations of creatinine and urea-nitrogen, tissue MDA level, TNF-α and ICAM-1 mRNA expressions, leukocyte infiltration and histopathologic injuries. Piperine administration significantly reduced the plasma concentrations of creatinine and urea-nitrogen, expression of pro-inflammatory factors, oxidative stress and renal histopathologic injuries. It is to be noted that 20 mg/kg dose was more effective.

Conclusion

Our results suggest piperine protects the kidney against ischemia-reperfusion induced acute kidney injuries by its anti-inflammatory and anti-oxidative properties.

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Renal ischemia-reperfusion increased the inflammation and oxidative stress parameters.

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Ischemia-reperfusion increased histopathological damages and functional parameters.

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Piperine pretreatment significantly reduced the inflammation and oxidative stress.

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Piperine administration ameliorated renal function and histopathologic damages.

SerpinA3 in the Early Recognition of Acute Kidney Injury to Chronic Kidney Disease (CKD) transition in the rat and its Potentiality in the Recognition of Patients with CKD

Recognizing patients at early phases of chronic kidney disease (CKD) is difficult, and it is even more challenging to predict acute kidney injury (AKI) and its transition to CKD. The gold standard to timely identify renal fibrosis is the kidney biopsy, an invasive procedure not usually performed for this purpose in clinical practice. SerpinA3 was identified by high-resolution-mass-spectrometry in urines from animals with CKD. An early and progressive elevation of urinary SerpinA3 (uSerpinA3) was observed during the AKI to CKD transition together with SerpinA3 relocation from the cytoplasm to the apical tubular membrane in the rat kidney. uSerpinA3/alpha-1-antichymotrypsin was significantly increased in patients with CKD secondary to focal and segmental glomerulosclerosis (FSGS), ANCA associated vasculitis (AAV) and proliferative class III and IV lupus nephritis (LN). uSerpinA3 levels were independently and positively associated with renal fibrosis. In patients with class V LN, uSerpinA3 levels were not different from healthy volunteers. uSerpinA3 was not found in patients with systemic inflammatory diseases without renal dysfunction. Our observations suggest that uSerpinA3 can detect renal fibrosis and inflammation, with a particular potential for the early detection of AKI to CKD transition and for the differentiation among lupus nephritis classes III/IV and V.

The Effect of Nitric Oxide on Remote Ischemic Preconditioning in Renal Ischemia Reperfusion Injury in Rats

Although remote ischemic preconditioning (RIPC) is an organ-protective maneuver from subsequent ischemia reperfusion injury (IRI) by application of brief ischemia and reperfusion to other organs, its mechanism remains unclear. However, it is known that RIPC reduces the heart, brain, and liver IRI, and that nitric oxide (NO) is involved in the mechanism of this effect. To identify the role of NO in the protective effect of RIPC in renal IRI, this study examined renal function, oxidative status, and histopathological changes using N-nitro-L-arginine methyl ester (L-NAME), an NO synthase inhibitor. Remote ischemic preconditioning was produced by 3 cycles of 5 minutes ischemia and 5 minutes reperfusion. Blood urea nitrogen, creatinine (Cr), and renal tissue malondialdehyde levels were lower, histopathological damage was less severe, and superoxide dismutase level was higher in the RIPC + IRI group than in the IRI group. The renoprotective effect was reversed by L-NAME. Obtained results suggest that RIPC before renal IRI contributes to improvement of renal function, increases antioxidative marker levels, and decreases oxidative stress marker levels and histopathological damage. Moreover, NO is likely to play an important role in this protective effect of RIPC on renal IRI.

l-NIL prevents the ischemia and reperfusion injury involving TLR-4, GST, clusterin, and NFAT-5 in mice

On renal ischemia-reperfusion (I/R) injury, recruitment of neutrophils during the inflammatory process promotes local generation of oxygen and nitrogen reactive species, which, in turn, are likely to exacerbate tissue damage. The mechanism by which inducible nitric oxide synthase (iNOS) is involved in I/R has not been elucidated. In this work, the selective iNOS inhibitor l- N6-(1-iminoethyl)lysine (l-NIL) and the NOS substrate l-arginine were employed to understand the role of NOS activity on the expression of particular target genes and the oxidative stress elicited after a 30-min of bilateral renal ischemia, followed by 48-h reperfusion in Balb/c mice. The main findings of the present study were that pharmacological inhibition of iNOS with l-NIL during an I/R challenge of mice kidney decreased renal injury, prevented tissue loss of integrity, and improved renal function. Several novel findings regarding the molecular mechanism by which iNOS inhibition led to these protective effects are as follows: 1) a prevention of the I/R-related increase in expression of Toll-like receptor 4 (TLR-4), and its downstream target, IL-1β; 2) reduced oxidative stress following the I/R challenge; noteworthy, this study shows the first evidence of glutathione S-transferase (GST) inactivation following kidney I/R, a phenomenon fully prevented by iNOS inhibition; 3) increased expression of clusterin, a survival autophagy component; and 4) increased expression of nuclear factor of activated T cells 5 (NFAT-5) and its target gene aquaporin-1. In conclusion, prevention of renal damage following I/R by the pharmacological inhibition of iNOS with l-NIL was associated with the inactivation of proinflammatory pathway triggered by TLR-4, oxidative stress, renoprotection (autophagy inactivation), and NFAT-5 signaling pathway.

A Si-rhodamine-based near-infrared fluorescent probe for visualizing endogenous peroxynitrite in living cells, tissues, and animals

An aromatic tertiary amine-functionalized Si-rhodamine dye has been exploited as a near-infrared fluorescent probe for visualizing endogenous peroxynitrite in living cells, tissues, and mice.

Aripiprazole prevents renal ischemia/reperfusion injury in rats, probably through nitric oxide involvement

Renal ischemia/reperfusion (I/R) injury is strongly related to morbidity and mortality. Oxidative stress, inflammation, and apoptosis play key roles in renal dysfunction following renal I/R. Aripiprazole is an atypical antipsychotic which used for the treatment of schizophrenia and bipolar disorder. Recent studies have reported aripiprazole as displaying certain anti-inflammatory effects. Regarding the underlying mechanisms of renal ischemia-reperfusion, therefore, nephroprotective effects might be predicted to be seen with aripiprazole. I/R injury was induced by bilateral clamping of the renal pedicles (45min) followed by reperfusion (24h). The mechanism of aripiprazole-mediated nephroprotection was explored by a combined use of aripiprazole and L-NAME (non-selective nitric oxide synthase inhibitor). Animals were given aripiprazole (2.5, 5, 10 and 20mg/kg) intraperitoneally, 30min before ischemia. L-NAME was administered before the aripiprazole injection. Serum creatinine and blood urea nitrogen were assessed after 24h of reperfusion. Serum levels of malondialdehyde (MDA), TNF-α and IL-1β were measured for rats treated with aripiprazole. The extent of necrosis was measured by the stereology method. Ischemia/reperfusion caused significant renal dysfunction and marked renal injury. Aripiprazole reduced creatinine and blood urea nitrogen. Serum levels of MDA, IL-1β and TNF-α were significantly lower in the aripiprazole group. Aripiprazole treatment also decreased the volume of kidney necrosis. The administration of L-NAME reversed the renoprotective effect of aripiprazole on BUN and creatinine, but enhanced the anti-necrotic effect of aripiprazole. The results show that a single dose of aripiprazole significantly improved renal function following ischemia/reperfusion injury - probably through the involvement of nitric oxide.

Inhibition of Oxidative Stress in Renal Ischemia-Reperfusion Injury

BACKGROUND

Superoxide, nitric oxide (NO), and peroxynitrite are important mediators in the pathogenesis of ischemia-reperfusion (I/R) injury. We tested the renoprotective effects of allopurinol (ALP), a xanthine oxidase inhibitor, N-nitro-L-arginine methyl ester (L-NAME), and 5,10,15,20-tetrakis (N-methyl-4-pyridyl) porphyrinato iron (III) (FeTMPyP) by selective inhibition of superoxide, NO, and peroxynitrite, respectively.

METHODS

Male Sprague-Dawley rats were randomly assigned to 5 groups (n = 6 per group). Group 1 was a sham-operated group. Group 2 was the renal I/R group (30-minute ischemia followed by 24-hour reperfusion). Rats in groups 3, 4, and 5 received ALP, L-NAME, or FeTMPyP, respectively, at 5 minutes before the reperfusion. Serum creatinine (Cr), blood urea nitrogen (BUN), renal tissue malondialdehyde, superoxide dismutase, histological changes, apoptosis, and monocyte infiltration were evaluated. In addition, the combined treatment with ALP and L-NAME was compared with FeTMPyP in a second independent experiment.

RESULTS

The administration of ALP, L-NAME, and FeTMPyP diminished the increase in Cr (P = .0066 for all) and BUN (P = .0066 for ALP; and P = .013 for L-NAME) induced by I/R injury and decreased the histological damage (P = .0066 for all). In addition, ALP, L-NAME, and FeTMPyP attenuated the oxidative stress response as determined by a decrease in malondialdehyde level (P = .0066 for all), apoptotic renal tubular cells (P = .0066 for all), and monocyte infiltration (P = .0066 for all). The combined treatment of ALP and L-NAME decreased Cr and BUN levels to a greater degree than FeTMPyP (P = .016 for Cr; P = .0079 for BUN).

CONCLUSIONS

Superoxide, NO, and peroxynitrite are involved in renal I/R injury. The reduction of peroxynitrite formation, via inhibition of superoxide or NO, or the induction of peroxynitrite decomposition may be beneficial in renal I/R injury.

Nafamostat Mesilate Attenuates Ischemia-Reperfusion-Induced Renal Injury

BACKGROUND

It has been reported that nafamostat mesilate (NM) inhibits inflammatory injury via inhibition of complement activation in ischemic heart, liver, and intestine. However, it is unclear if NM also inhibits apoptosis in ischemia-reperfusion (IR)-injured kidney. We therefore investigated whether NM attenuates IR renal injury that involves inhibition of apoptosis.

METHODS

HK-2 cells and male C57BL/6 mice were used for this study. C57Bl/6 mice were divided into 4 groups: sham, NM (2 mg/kg) + sham, IR injury (IR injury; reperfusion 27 minutes after clamping of both the renal artery and vein), and NM + IR injury. Kidneys were harvested 24 hours after IR injury, and functional and molecular parameters were evaluated. For in vitro studies, HK-2 cells were incubated for 6 hours with mineral paraffin oil to induce hypoxic injury, and then treated with various doses of NM to evaluate the antiapoptotic effects.

RESULTS

Blood urea nitrogen, serum creatinine levels, and renal tissue injury scores in NM + IR-injured mice were significantly lower than those of control IR mice (all P < .01). NM significantly improved cell survival in hypoxic HK-2 cells (P < .01), significantly decreased renal Bax expression (P < .05), and increased renal Bcl-2 protein levels in IR kidneys and hypoxic HK-2 cells compared with those of the sham and control groups. The numbers of terminal deoxynucleotide transferase-mediated dUTP nick-end labeling- and 8-oxo-2'-deoxyguanosine-positive cells were significantly lower in NM + IR-injured kidneys compared with those in control IR-injured mice (P < .05); NM treatment decreased the expression of inducible and endothelial nitric oxide synthase in IR-injured mice (P < .05).

CONCLUSIONS

NM ameliorates IR renal injury via inhibition of apoptosis by, at least in part, lowering nitric oxide overproduction, reducing Bax, and increasing Bcl-2.

Opportunities for the repurposing of PARP inhibitors for the therapy of non-oncological diseases

The recent clinical availability of the PARP inhibitor olaparib (Lynparza) opens the door for potential therapeutic repurposing for non-oncological indications. Considering (a) the preclinical efficacy data with PARP inhibitors in non-oncological diseases and (b) the risk-benefit ratio of treating patients with a compound that inhibits an enzyme that has physiological roles in the regulation of DNA repair, we have selected indications, where (a) the severity of the disease is high, (b) the available therapeutic options are limited, and (c) the duration of PARP inhibitor administration could be short, to provide first-line options for therapeutic repurposing. These indications are as follows: acute ischaemic stroke; traumatic brain injury; septic shock; acute pancreatitis; and severe asthma and severe acute lung injury. In addition, chronic, devastating diseases, where alternative therapeutic options cannot halt disease development (e.g. Parkinson's disease, progressive multiple sclerosis or severe fibrotic diseases), should also be considered. We present a preclinical and clinical action plan for the repurposing of PARP inhibitors.

LINKED ARTICLES

This article is part of a themed section on Inventing New Therapies Without Reinventing the Wheel: The Power of Drug Repurposing. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.2/issuetoc.

Poly(ADP-ribose) polymerase inhibition suppresses inflammation and promotes recovery from adrenal injury in a rat model of acute necrotizing pancreatitis

Background

Poly(ADP-ribose) polymerase (PARP) participates in multi-organ failure in various inflammatory diseases including acute necrotizing pancreatitis (ANP). Since pancreatitis-associated adrenal insufficiency is partly caused by inflammatory damage to the adrenal cortex, we examined whether PARP antagonism could alleviate adrenal insufficiency in a rat model of ANP.

Methods

ANP was induced by retrograde infusion of sodium taurocholate into the bile-pancreatic duct. At 30 min prior to taurocholate infusion, rats were pretreated with the PARP inhibitor 3-Aminobenzamide (3-AB, 20 mg/kg) or vehicle. Pancreatic pathological injury, adrenal histology, neutrophil infiltration, cell apoptosis, and serum corticosterone level were assessed at various times points. Activities of poly(ADP-ribosyl)ated protein (PAR), nuclear factor-kappaB (NF-kB), tumor necrosis factor-α (TNF-α), intercellular adhesion molecule-1 (ICAM-1) and inducible nitric oxide synthase (iNOS) in the adrenal were also examined.

Results

PARP overactivation in ANP rats is associated with reduced serum corticosterone level and marked cellular alterations in adrenocortical tissue. Inflammatory stress caused by ANP reduced adrenal corticosterone release. 3-AB reduced the activation of PARP and inflammatory markers, decreased myeloperoxidase activity, attenuated adrenal morphologic lesions and cells apoptosis, simultaneously improved the impaired adrenal function.

Conclusions

Our data demonstrate the involvement of PARP overactivation in the pathogenesis of adrenal dysfunction after ANP. PARP inhibition may suppress inflammation and promote functional recovery from adrenal injury.

WNT Agonist Decreases Tissue Damage and Improves Renal Function After Ischemia-Reperfusion

Renal ischemia-reperfusion (IR) injury (IRI) after shock states or transplantation causes tissue damage and delayed graft function, respectively. The Wnt/β-catenin signaling pathway plays a critical role in nephrogenesis. We therefore hypothesized that pharmacological activation of the Wnt/β-catenin signaling by the Wnt agonist, a synthetic pyrimidine, could protect kidneys from IRI. Adult male rats were subjected to bilateral clamping of the renal pedicles with microvascular clips for 60 min, followed by reperfusion. The Wnt agonist (5 mg/kg body weight) or vehicle (20% dimethyl sulfoxide in saline) was administered intravenously 1 h before ischemia. Blood and renal tissues were collected 24 h after IR for evaluation. Renal IR caused a significant reduction of β-catenin and its downstream target gene cyclin D1 by 65% and 39%, respectively, compared with the sham, whereas the Wnt agonist restored them to sham levels. The number and intensity of cells staining with the proliferation marker Ki67 in ischematized kidneys were enhanced by the Wnt agonist. The integrity of the renal histological architecture in the Wnt agonist group was better preserved than the vehicle group. The Wnt agonist significantly lowered serum levels of creatinine, aspartate aminotransferase, and lactate dehydrogenase and inhibited the production of interleukin 6 and interleukin 1β and myeloperoxidase activities. Lastly, the Wnt agonist reduced inducible nitric oxide synthase, nitrotyrosine proteins, and 4-hydroxynonenal in the kidneys by 60%, 47%, and 21%, respectively, compared with the vehicle. These results indicate that the Wnt agonist improves renal regeneration and function while attenuating inflammation and oxidative stress in the kidneys after IR. Thus, pharmacologic stimulation of the Wnt/β-catenin signaling provides a beneficial effect on the prevention of renal IRI.

Role of S-methylisothiourea (SMT) in renal ischemia/reperfusion injury in rats

Introduction: Excessive production of nitric oxide (NO) via inducible nitric oxide synthase (iNOS) is associated in renal ischemia reperfusion injury (IRI).

Objectives: This study was designed to investigate the role of S-methylisothiourea (SMT) as selective inhibitor iNOS in renal IRI. Materials and Methods: Male Wistar rats were subjected to 45 minutes of bilateral renal ischemia by occlusion of renal vessels of both kidney followed by 24 hours of reperfusion. Prior to renal IRI, the rats received either vehicle (saline, group 2) or SMT (50 mg/kg, group 3), and were compared with the sham-operated animals (group 1). At the end of reperfusion period, the rats were sacrificed for kidney tissue pathology investigation.

Results: Serum creatinine (Cr), blood urea nitrogen (BUN), nitrite levels, and kidney weight significantly increased in groups 2 and 3 (P < 0.05). Kidney tissue damage scores in groups 2 and 3 were also higher than that in the sham-operated group (P < 0.05).

Conclusion: SMT not only prevent the kidney during IRI, but also promotes kidney function disturbance and severity of renal injury.

Correlation of cystatin C and creatinine based estimates of renal function in children with hydronephrosis

INTRODUCTION

The use of a simple and accurate glomerular filtration rate (GFR) estimating method aiming minute assessment of renal function can be of great clinical importance.

OBJECTIVES

This study aimed to determine the association of a GFR estimating by equation that includes only cystatin C (Gentian equation) to equation that include only creatinine (Schwartz equation) among children.

PATIENTS AND METHODS

A total of 31 children aged from 1 day to 5 years with the final diagnosis of unilateral or bilateral hydronephrosis referred to Besat hospital in Hamadan, between March 2010 and February 2011 were consecutively enrolled. Schwartz and Gentian equations were employed to determine GFR based on plasma creatinine and cystatin C levels, respectively.

RESULTS

The proportion of GFR based on Schwartz equation was 70.19± 24.86 ml/min/1.73 m(2), while the level of this parameter based on Gentian method and using cystatin C was 86.97 ± 21.57 ml/min/1.73 m(2). The Pearson correlation coefficient analysis showed a strong direct association between the two levels of GFR measured by Schwartz equation based on serum creatinine level and Gentian method and using cystatin C (r = 0.594, P < 0.001). The linear association between GFR values measured with the two methods included cystatin C based GFR = 50.8+ 0.515 × Schwartz GFR. The correlation between GFR values measured by using serum creatinine and serum cystatin C measurements remained meaningful even after adjustment for patients' gender and age (r = 0.724, P < 0.001).

CONCLUSION

The equation developed based on cystatin C level is comparable with another equation, based on serum creatinine (Schwartz formula) to estimate GFR in children.

Distant effects of unilateral renal ischemia/reperfusion on contralateral kidney but not lung in rats: the roles of ROS and iNOS

Acute kidney injury is usually associated with distant organ dysfunction. The roles of inducible nitric oxide synthase (iNOS) and reactive oxygen species (ROS) in this phenomenon were investigated following 2 h unilateral renal ischemia and 24 h reperfusion. There were 3 groups of rats subjected to either unilateral ischemia/reperfusion (UIR group), unilateral nephrectomy (UNX group), or sham operation. Two further groups were given α-tocopherol and aminoguanidine with UIR (treated-UIR group) and UNX (treated-UNX group). Plasma nitrite/nitrate and malondialdehyde were elevated only in the UIR group. Creatinine clearance and blood flow increased in non-ischemic kidney of the UIR, but not to the same extent as remnant kidney of the UNX group, while they had equal compensatory rises in absolute Na(+) and K(+) excretion and urine flow. Non-ischemic kidney of the treated-UIR group, but not remnant kidney of the treated-UNX group, showed more elevation in blood flow, whereas both kidneys had reductions in absolute Na(+) excretion and urine flow. Respiratory functional variable were not different between all groups. Therefore, 2 h unilateral renal ischemia and 24 h reperfusion did not affect lung but had distant effects on contralateral kidney partly mediated by ROS and NO-derived from iNOS to dampen compensatory increases in renal hemodynamics and to decrease tubular reabsorption.

Novel resveratrol analogues attenuate renal ischemic injury in rats

BACKGROUND

Renal ischemia-reperfusion (I/R) is a severe clinical complication with no specific treatment. Resveratrol has been shown as a promising experimental agent in renal I/R due to its effect on cellular energy metabolism, oxidative stress, and inflammation. Recently, we identified two biologically active resveratrol analogues (RSVAs), RSVA405 and RSVA314. We hypothesized that both RSAVs would attenuate I/R-induced renal injury.

METHODS

Adult male rats were subjected to renal I/R through bilateral renal pedicle clamping for 60 min, followed by reperfusion. RSVA405 (3 mg/kg Body Weight), RSVA314 (3 mg/kg Body Weight), or vehicle (10% dimethyl sulfoxide and 33% Solutol in phosphate buffered saline) were administered by intraperitoneal injection 1 h before ischemia. Blood and renal tissues were collected 24 h after I/R for evaluation.

RESULTS

Administration of RSVA405 and RSVA314 significantly reduced the serum levels of renal dysfunction and injury markers, including creatinine, blood urea nitrogen, aspartate aminotransferase, and lactate dehydrogenase, compared with vehicle. The protective effect of RSVA405 and RSVA314 was also reflected on histologic evaluation. Both RSVAs reduced the number of apoptotic cells by more than 60% as determined by transferase dUTP nick end labeling assay, compared with vehicle. The renal adenosine triphosphate levels of the vehicle group was decreased to 52.4% of control, whereas those of the RSVA405 and RSVA314 groups were restored to 72.3% and 79.6% of control, respectively. Both RSVAs significantly reduced the protein expression of inducible nitric oxide synthase and nitrotyrosine and the messenger RNA levels of tumor necrosis factor-α, interleukin-6, and interleukin-1β.

CONCLUSIONS

RSVA405 and RSVA314 attenuate I/R-induced renal injury through the modulation of energy metabolism, oxidative stress, and inflammation.

1400W reduces ischemia reperfusion injury in an ex-vivo porcine model of the donation after circulatory death kidney donor

AIM: To investigate the effects of 1400W-a selective inducible nitric oxide synthase (iNOS) inhibitor in a model of donation after circulatory death (DCD) kidneys.

METHODS: Porcine kidneys were retrieved after 25 min warm ischemia. They were then stored on ice for 18 h before being reperfused ex vivo with oxygenated autologous blood on an isolated organ perfusion system. The selective iNOS inhibitor 1400W (10 mg/kg) was administered before reperfusion (n = 6) vs control group (n = 7). Creatinine (1000 μmol/L) was added to the system, renal and tubular cell function and the level of ischemia reperfusion injury were assessed over 3 h of reperfusion using plasma, urine and tissue samples.

RESULTS: Kidneys treated with 1400W had a higher level of creatinine clearance (CrCl) [area under the curve (AUC) CrCl: 2.37 ± 0.97 mL/min per 100 g vs 0.96 ± 0.32 mL/min per 100 g, P = 0.004] and urine output [Total: 320 ± 96 mL vs 156 ± 82 mL, P = 0.008]. There was no significant difference in levels of fractional excretion of sodium (AUC, Fr ex Na+: Control, 186.3% ± 81.7%.h vs 1400W, 153.4% ± 12.1%.h, P = 0.429). Levels of total protein creatinine ratio were significantly lower in the 1400W group after 1 h of reperfusion (1h Pr/Cr: 1400W 9068 ± 6910 mg/L/mmol/L vs Control 21586 ± 5464 mg/L/mmol/L, P = 0.026). Levels of 8-isoprostane were significantly lower in the 1400W group [8-iso/creatinine ratio: Control 239 ± 136 pg/L/mmol/L vs 1400W 139 ± 47 pg/L/mmol/L, P = 0.041].

CONCLUSION: This study demonstrated that 1400W reduced ischaemia reperfusion injury in this porcine kidney model of DCD donor. Kidneys had improved renal function and reduced oxidative stress.

Therapeutic applications of PARP inhibitors: anticancer therapy and beyond

The aim of this article is to describe the current and potential clinical translation of pharmacological inhibitors of poly(ADP-ribose) polymerase (PARP) for the therapy of various diseases. The first section of the present review summarizes the available preclinical and clinical data with PARP inhibitors in various forms of cancer. In this context, the role of PARP in single-strand DNA break repair is relevant, leading to replication-associated lesions that cannot be repaired if homologous recombination repair (HRR) is defective, and the synthetic lethality of PARP inhibitors in HRR-defective cancer. HRR defects are classically associated with BRCA1 and 2 mutations associated with familial breast and ovarian cancer, but there may be many other causes of HRR defects. Thus, PARP inhibitors may be the drugs of choice for BRCA mutant breast and ovarian cancers, and extend beyond these tumors if appropriate biomarkers can be developed to identify HRR defects. Multiple lines of preclinical data demonstrate that PARP inhibition increases cytotoxicity and tumor growth delay in combination with temozolomide, topoisomerase inhibitors and ionizing radiation. Both single agent and combination clinical trials are underway. The final part of the first section of the present review summarizes the current status of the various PARP inhibitors that are in various stages of clinical development. The second section of the present review summarizes the role of PARP in selected non-oncologic indications. In a number of severe, acute diseases (such as stroke, neurotrauma, circulatory shock and acute myocardial infarction) the clinical translatability of PARP inhibition is supported by multiple lines of preclinical data, as well as observational data demonstrating PARP activation in human tissue samples. In these disease indications, PARP overactivation due to oxidative and nitrative stress drives cell necrosis and pro-inflammatory gene expression, which contributes to disease pathology. Accordingly, multiple lines of preclinical data indicate the efficacy of PARP inhibitors to preserve viable tissue and to down-regulate inflammatory responses. As the clinical trials with PARP inhibitors in various forms of cancer progress, it is hoped that a second line of clinical investigations, aimed at testing of PARP inhibitors for various non-oncologic indications, will be initiated, as well.

Emerging role of gasotransmitters in renal transplantation

Once patients with kidney disease progress to end-stage renal failure, transplantation is the preferred option of treatment resulting in improved quality of life and reduced mortality compared to dialysis. Although 1-year survival has improved considerably, graft and patient survival in the long term have not been concurrent, and therefore new tools to improve long-term graft and patient survival are warranted. Over the past decades, the gasotransmitters nitric oxide (NO), carbon monoxide (CO) and hydrogen sulfide (H2S) have emerged as potent cytoprotective mediators in various diseases. All three gasotransmitters are endogenously produced messenger molecules that possess vasodilatory, anti-apoptotic, anti-inflammatory and anti-oxidant properties by influencing an array of intracellular signaling processes. Although many regulatory functions of gasotransmitters have overlapping actions, differences have also been reported. In addition, crosstalk between NO, CO and H2S results in synergistic regulatory effects. Endogenous and exogenous manipulation of gasotransmitter levels modulates several processes involved in renal transplantation. This review focuses on mechanisms of gas-mediated cytoprotection and complex interactions between gasotransmitters in renal transplantation.

Tyrosol attenuates ischemia-reperfusion-induced kidney injury via inhibition of inducible nitric oxide synthase

Tyrosol is a natural phenolic antioxidant compound. Oxidative stress represents one of the important mechanisms underlying ischemia-reperfusion-induced kidney injury. The aim of this study was to investigate the effect of tyrosol against ischemia-reperfusion-induced acute kidney injury. The left kidney of Sprague-Dawley rats was subjected to 45 min of ischemia followed by reperfusion for 6 h. Ischemia-reperfusion caused an increase in peroxynitrite formation and lipid peroxidation. The level of nitric oxide (NO) metabolites and the mRNA of inducible nitric oxide synthase (iNOS) were elevated in ischemia-reperfused kidneys. Administration of tyrosol (100 mg/kg body weight) to rats prior to the induction of ischemia significantly reduced peroxynitrite formation, lipid peroxidation, and the level of NO metabolites. Tyrosol administration also attenuated ischemia-reperfusion-induced NF-κB activation and iNOS expression. Such a treatment improved kidney function. Results suggest that tyrosol may have a protective effect against acute kidney injury through inhibition of iNOS-mediated oxidative stress.

Inhibiting inducible nitric oxide synthase with rutin reduces renal ischemia/reperfusion injury

BACKGROUND

Nitric oxide (NO) seems to play an important role during renal ischemia/reperfusion (I/R) injury. We investigated whether rutin inhibits inducible nitric oxide synthase (iNOS) and reduces 3-nitrotyrosine (3-NT) formation in the kidneys of rats during I/R.

METHODS

Wistar albino rats were nephrectomized unilaterally and, 2 weeks later, subjected to 45 minutes of left renal pedicle occlusion followed by 3 hours of reperfusion. We intraperitoneally administered L-N6-(1-iminoethyl)lysine (L-NIL; 3 mg/kg) for 30 minutes or rutin (1 g/kg) for 60 minutes before I/R. After reperfusion, kidney samples were taken for immunohistochemical analysis of iNOS and 3-NT. We measured plasma nitrite/nitrate and cyclic guanosine monophosphate (cGMP) to evaluate NO levels.

RESULTS

Ischemia/reperfusion caused plasma cGMP to increase significantly. Similarly, plasma nitrite/nitrate was elevated in the I/R group compared with the control group. Histochemical staining was positive for iNOS and 3-NT in the I/R group. Pretreatment with L-NIL or rutin significantly mitigated the elevation of plasma cGMP and nitrite/nitrate. These changes in biochemical parameters were also associated with changes in immunohistochemical appearance. Pretreatment with L-NIL or rutin significantly decreased the incidence and severity of iNOS and 3-NT formation in the kidney tissues.

CONCLUSION

Our findings suggest that high activity of iNOS causes renal I/R injury, and that rutin exerts protective effects, probably by inhibiting iNOS.

Palmitoylethanolamide reduces early renal dysfunction and injury caused by experimental ischemia and reperfusion in mice

This study was designed to assess a protective effect of palmitoylethanolamide (PEA) in the development of inflammation after ischemia-reperfusion injury of the kidney. Moreover, to suggest a possible mechanism, renal ischemia-reperfusion was performed in mice with targeted disruption of peroxisome proliferator-activated receptor α (PPAR-α) gene (PPAR-αKO) to explain whether the observed PEA effect was dependent on PPAR-α pathway. Peroxisome proliferator-activated receptor-αKO and littermate wild-type controls (PPAR-αWT) were subjected to bilateral renal artery occlusion (30 min) and reperfusion (6 h) and received PEA (10 mg/kg i.p.) 15 min before release of clamps. Serum and urinary indicators of renal dysfunction and tubular and reperfusion injury were measured, specifically serum urea, creatinine, aspartate aminotransferase and γ-glutamyl transferase, and creatinine clearance. In addition, renal sections were used for histological scoring of renal injury and for immunologic evidence of nitrotyrosine formation, poly[adenosine diphosphate-ribose] (PAR), and adhesion molecules expression. The oxidative stress-sensitive nuclear factor κB signaling pathway was also investigated by Western blot analysis. Kidney myeloperoxidase activity and malondialdehyde levels were measured for assessment of polymorphonuclear leukocyte cell infiltration and lipid peroxidation, respectively. Apoptotic mechanisms were also investigated. Moreover, the infiltration and activation of mast cells were explored. In vivo, PEA administration during ischemia significantly reduced the increase in (i) creatinine, γ-glutamyl transferase, aspartate aminotransferase; (ii) nuclear translocation of nuclear factor κB p65; (iii) kidney myeloperoxidase activity and malondialdehyde levels; (iv) nitrotyrosine, PAR, and adhesion molecules expression; (v) the infiltration and activation of mast cells; and (vi) apoptosis. Our results clearly demonstrate that PEA significantly attenuated the degree of renal dysfunction, injury, and inflammation caused by ischemia-reperfusion injury. Moreover, the positive effects of PEA were at least in part dependent on PPAR-α pathway.

Arginine-based inhibitors of nitric oxide synthase: therapeutic potential and challenges

In the past three decades, nitric oxide has been well established as an important bioactive molecule implicated in regulation of cardiovascular, nervous, and immune systems. Therefore, it is not surprising that much effort has been made to find specific inhibitors of nitric oxide synthases (NOS), the enzymes responsible for production of nitric oxide. Among the many NOS inhibitors developed to date, inhibitors based on derivatives and analogues of arginine are of special interest, as this category includes a relatively high number of compounds with good potential for experimental as well as clinical application. Though this group of inhibitors covers early nonspecific compounds, modern drug design strategies such as biochemical screening and computer-aided drug design have provided NOS-isoform-specific inhibitors. With an emphasis on major advances in this field, a comprehensive list of inhibitors based on their structural characteristics is discussed in this paper. We provide a summary of their biochemical properties as well as their observed effects both in vitro and in vivo. Furthermore, we focus in particular on their pharmacology and use in recent clinical studies. The potential of newly designed specific NOS inhibitors developed by means of modern drug development strategies is highlighted.

Ischaemic/reperfusion injury: Role of infliximab

Ischaemia/reperfusion (I/R) injury is an underlying complex interrelated patho-physiological process which effects the outcome of many clinical situations, in particular transplantation. Tumor necrosis factor (TNF)-α is a pleiotropic inflammatory cytokine; a trimeric protein encoded within the major histocompatibility complex which plays a pivotal role in this disease process. This review is based at looking into an update, particularly the new insights in the mechanisms of action of TNF antagonist such as infliximab. Infliximab may thus play a dual role in the field of transplantation where it might not only down regulate the I/R injury, it may also have a beneficial role in the reduction of acute rejection.

Stimulation of carnitine palmitoyltransferase 1 improves renal function and attenuates tissue damage after ischemia/reperfusion

BACKGROUND

Renal injury as a result of ischemia/reperfusion (I/R) is a major clinical problem with a high mortality rate and a lack of therapeutic treatment. During I/R, cellular homeostasis is disrupted owing to energy depletion, leading to cell death. Fatty acid β-oxidation is the major metabolic pathway for generating adenosine triphosphate (ATP) in the kidneys, which is governed by carnitine palmitoyltransferase 1 (CPT1). C75 is a synthetic compound that up-regulates CPT1 activity. Thus, we hypothesized that C75 treatment could increase energy production and alleviate renal I/R injury.

METHODS

We subjected male adult rats to renal I/R by bilateral renal pedicle clamping with microvascular clips for 60 min, followed by administration of 8% dimethyl sulfoxide (vehicle) or C75 (3 mg/kg body weight), with 5 animals/group. We collected blood and renal tissues 24 h after reperfusion and subjected them to various measurements and histological examination.

RESULTS

C75 treatment restored the loss of CPT1 activity and intracellular ATP levels in the kidneys after I/R. Administration of C75 significantly lowered serum creatinine, blood urea nitrogen, aspartate aminotransferase, and lactate dehydrogenase levels elevated by I/R. C75 treatment preserved morphological features of the kidneys with a significant improvement in the damage score. In addition, C75 treatment inhibited the increase of TNF-α levels in serum and kidneys, and lowered myeloperoxidase activity in the kidneys after I/R.

CONCLUSIONS

Stimulation of CPT1 activity by C75 recovered ATP depletion, improved renal function, attenuated tissue injury, and inhibited proinflammatory cytokine production and neutrophil infiltration after renal I/R injury. Therefore, enhancing the metabolism pathways for energy production may provide a novel modality to treat renal I/R injury.

Delayed administration of pyroglutamate helix B surface peptide (pHBSP), a novel nonerythropoietic analog of erythropoietin, attenuates acute kidney injury

In preclinical studies, erythropoietin (EPO) reduces ischemia-reperfusion-associated tissue injury (for example, stroke, myocardial infarction, acute kidney injury, hemorrhagic shock and liver ischemia). It has been proposed that the erythropoietic effects of EPO are mediated by the classic EPO receptor homodimer, whereas the tissue-protective effects are mediated by a hetero-complex between the EPO receptor monomer and the β-common receptor (termed "tissue-protective receptor"). Here, we investigate the effects of a novel, selective-ligand of the tissue-protective receptor (pyroglutamate helix B surface peptide [pHBSP]) in a rodent model of acute kidney injury/dysfunction. Administration of pHBSP (10 μg/kg intraperitoneally [i.p.] 6 h into reperfusion) or EPO (1,000 IU/kg i.p. 4 h into reperfusion) to rats subjected to 30 min ischemia and 48 h reperfusion resulted in significant attenuation of renal and tubular dysfunction. Both pHBSP and EPO enhanced the phosphorylation of Akt (activation) and glycogen synthase kinase 3β (inhibition) in the rat kidney after ischemia-reperfusion, resulting in prevention of the activation of nuclear factor-κB (reduction in nuclear translocation of p65). Interestingly, the phosphorylation of endothelial nitric oxide synthase was enhanced by EPO and, to a much lesser extent, by pHBSP, suggesting that the signaling pathways activated by EPO and pHBSP may not be identical.

Post-treatment with the combination of 5-aminoimidazole-4-carboxyamide ribonucleoside and carnitine improves renal function after ischemia/reperfusion injury

Renal ischemia/reperfusion (I/R) injury is a major clinical problem where main metabolic pathways are compromised and cellular homeostasis crashes after ATP depletion. Fatty acids are major energy source in the kidneys. Carnitine palmitoyltransferase I (CPT1), a mitochondrial membrane enzyme, utilizes carnitine to transport fatty acids to mitochondria for the process of β-oxidation and ATP generation. In addition, CPT1 activity is indirectly regulated by adenosine monophosphate-activated protein kinase, which can be activated by 5-aminoimidazole-4-carboxyamide ribonucleoside (AICAR). We hypothesized that administration of carnitine and AICAR could reestablish the energetic balance after reperfusion and ameliorate renal I/R injury. Male adult rats were subjected to renal I/R by bilateral renal pedicle clamping for 60 min, followed by administration of saline (vehicle), carnitine (250 mg/kg BW), AICAR (30 mg/kg BW), or combination of both drugs. Blood and renal tissues were collected 24 h after reperfusion for various measurements. Renal carnitine levels decreased 53% after I/R. The combined treatment significantly increased CPT1 activity and ATP levels and lowered renal malondialdehyde and serum TNF-α levels against the vehicle group. It led to improvement in renal morphology and histological damage score associated with diminution in serum creatinine, blood urea nitrogen, and aspartate aminotransferase levels. Moreover, the combined treatment significantly improved the survival rate in comparison to the vehicle group. In contrast, administration of either drug alone did not show a significant improvement in most of the measurements. In conclusion, enhancing energy metabolism by combination of carnitine and AICAR provides a novel modality to treat renal I/R injury.

Rosiglitazone affects nitric oxide synthases and improves renal outcome in a rat model of severe ischemia/reperfusion injury

Background. Nitric oxide (NO)-signal transduction plays an important role in renal ischemia/reperfusion (I/R) injury. NO produced by endothelial NO-synthase (eNOS) has protective functions whereas NO from inducible NO-synthase (iNOS) induces impairment. Rosiglitazone (RGZ), a peroxisome proliferator-activated receptor (PPAR)-γ agonist exerted beneficial effects after renal I/R injury, so we investigated whether this might be causally linked with NOS imbalance. Methods. RGZ (5 mg/kg) was administered i.p. to SD-rats (f) subjected to bilateral renal ischemia (60 min). Following 24 h of reperfusion, inulin- and PAH-clearance as well as PAH-net secretion were determined. Morphological alterations were graded by histopathological scoring. Plasma NO_x-production was measured. eNOS and iNOS expression was analyzed by qPCR. Cleaved caspase 3 (CC3) was determined as an apoptosis indicator and ED1 as a marker of macrophage infiltration in renal tissue. Results. RGZ improves renal function after renal I/R injury (PAH-/inulin-clearance, PAH-net secretion) and reduces histomorphological injury. Additionally, RGZ reduces NO_x plasma levels, ED-1 positive cell infiltration and CC3 expression. iNOS-mRNA is reduced whereas eNOS-mRNA is increased by RGZ. Conclusion. RGZ has protective properties after severe renal I/R injury. Alterations of the NO pathway regarding eNOS and iNOS could be an explanation of the underlying mechanism of RGZ protection in renal I/R injury.

Delayed graft function in the kidney transplant

Acute kidney injury occurs with kidney transplantation and too frequently progresses to the clinical diagnosis of delayed graft function (DGF). Poor kidney function in the first week of graft life is detrimental to the longevity of the allograft. Challenges to understand the root cause of DGF include several pathologic contributors derived from the donor (ischemic injury, inflammatory signaling) and recipient (reperfusion injury, the innate immune response and the adaptive immune response). Progressive demand for renal allografts has generated new organ categories that continue to carry high risk for DGF for deceased donor organ transplantation. New therapies seek to subdue the inflammatory response in organs with high likelihood to benefit from intervention. Future success in suppressing the development of DGF will require a concerted effort to anticipate and treat tissue injury throughout the arc of the transplantation process.

Erythropoietin preserves the integrity and quality of organs for transplantation after cardiac death

Previous studies have shown that treatment with erythropoietin (EPO) exerts important cytoprotective and antiapoptotic effects. Donor organs recovered after cardiac death (DCD) can alleviate the shortage of organs required for transplantation. However, organs obtained subsequent to cardiac death demonstrate an increased incidence of delayed graft function and primary nonfunction. The aim of this study was to determine the effects of EPO administration to the donor in a porcine model of kidney transplantation under DCD conditions. Landrace pigs received 1,000 IU/kg i.v. EPO 30 min before cardiac arrest. Kidneys were then subjected to 30 min of warm ischemia and were transplanted after 24 h of cold storage. Renal dysfunction, injury, and inflammation were evaluated 4 h after transplantation. Transplantation of kidneys from DCD resulted in significant renal dysfunction, injury, and inflammation. This study provides the first evidence that pretreatment of the donor with a single pharmacologically relevant dose of EPO causes substantial attenuation of the dysfunction and injury associated with the transplantation of kidneys recovered after cardiac death.

Notoginsenoside R1 attenuates renal ischemia-reperfusion injury in rats

Ischemia-reperfusion (I/R) injury of the kidney is a complex pathophysiological process and a major cause of acute renal failure. It has been shown that I/R injury is related to inflammatory responses and activation of apoptotic pathways. Inhibition of certain elements of inflammatory responses and apoptotic pathway seemed to ameliorate renal I/R injury. As an effective element of Panax notoginseng, NR1 has antioxidant, anti-inflammatory, antiapoptotic, and immune-stimulatory activities. Therefore, we speculate that NR1 can attenuate renal I/R injury. Ischemia-reperfusion injury was induced by renal pedicle ligation followed by reperfusion along with a contralateral nephrectomy. Male Sprague-Dawley rats were randomized to four groups: sham group, I/R control group, NR1-1 group (rats treated with NR1, 20 mg.kg.d) and NR1-2 group (rats treated with NR1, 40 mg.kg.d). All animals were killed 72 h after I/R induction. Blood and renal tissues were collected. Renal dysfunction was observed by the level of serum creatinine and histological evaluation. Apoptosis and inflammatory response in the tissue of kidney were detected mainly with molecular biological methods. NR1 attenuated I/R-induced renal dysfunction as indicated by the level of serum creatinine and histological evaluation. It prevented the I/R-induced increases in the levels of proinflammatory cytokine TNF-alpha, myeloperoxidase activity, phosphorylation of p38, and activation of nuclear factor kappaB with cell apoptosis in the kidney and enhanced expression of antiapoptosis cytokine bcl-2. Treatment with NR1 improves renal function after I/R associated with a significant reduction in cell apoptosis and inflammatory responses, which may be related to p38 and nuclear factor kappaB inhibition.