Role of reactive oxygen metabolites in experimental glomerular disease

Renoprotective Effects of Mineralocorticoid Receptor Antagonists Against Diabetic Kidney Disease

Diabetic kidney disease (DKD) is a growing epidemic worldwide and a leading cause of end-stage kidney disease. Mineralocorticoid receptor (MR) blockade using Finerenone is a recently approved therapeutic approach to slow down the progression of DKD in patients with type 2 diabetes in addition to other therapies such as angiotensin-II converting enzyme inhibitors (ACEIs), angiotensin II receptor blockers (ARBs), sodium-glucose co-transporter 2 (SGLT2) inhibitors, and glucagon-like peptide 1 (GLP-1) analogs. This review elaborates on the pathophysiologic pathways activated by aldosterone (the human mineralocorticoid) in DKD, the pharmacology of three different generations of mineralocorticoid receptor antagonists (MRAs), specifically, spironolactone, eplerenone, and finerenone, and the mechanisms by which these MRAs elicit their protective effects on the kidney under diabetic settings.

L-methionine protects against nephrotoxicity induced by methotrexate through modulation of redox status and inflammation

Objective: Methotrexate (MTX) is a drug used in the treatment of cancer and autoimmune disorders; however, its clinical use is limited because of serious side effects including renal toxicity. This study aimed to investigate the protective effect of Lmethionine (L-Met) on MTX toxicity in the kidneys of rats.Methods: Thirty male rats were divided equally into five groups: control (saline), Met400 (400 mg/kg L-Met), MTX (20 mg/kg MTX), MTX-Met300 (300 mg/kg L-Met and 20 mg/kg MTX), and MTX-Met400 (400 mg/kg L-Met and 20 mg/kg MTX). Rats were euthanized one day after the last dose administration (day 16) and serum and renal tissue samples were collected. Renal function and injury indices, oxidative stress/antioxidant indices and proinflammatory cytokines were evaluated.Results: The results showed that L-Met could effectively counteract the nephrotoxic effects of MTX, in a dose-related manner, by improving most of the tested parameters. Furthermore, the higher dose of L-Met was able to restore several parameters to normal levels. In addition, investigation of MTX-induced hematological changes revealed a corrective potential of L-Met.Conclusion: L-Met can be an effective adjuvant therapy to modulate renal toxicity associated with MTX because of its antioxidant and antiinflammatory effects.

Sodium Pyruvate Nasal Spray Reduces the Severity of Nasal Inflammation and Congestion in Patients with Allergic Rhinitis

Background: As an anti-inflammatory and antioxidant, sodium pyruvate significantly reduces inflammatory cytokines and oxygen radicals such as interleukin (IL) IL-6, IL-8, Monocyte Chemoattractant Protein-1, and hydrogen peroxide. Thus, sodium pyruvate holds promise as a treatment for many respiratory diseases, including allergic rhinitis (AR). Novel treatments for AR are needed as current medications, including steroids, often fail to treat severe symptoms. Methods: The data from five human clinical studies were analyzed to determine the effect of 20 mM sodium pyruvate nasal spray (N115) in patients with AR. Nasal inflammation scores were compared to a placebo control or a no-treatment baseline control. Three studies were open-labeled and two were appropriately blinded to both patients and clinicians using computer randomization of subjects. Results: The intranasal administration of sodium pyruvate significantly improved nasal inflammation scores in all five clinical trials of patients with AR (p < 0.0001 in all trials). Conclusions: These results give credence to the overall ability of sodium pyruvate, administered by nasal spray, to treat inflammation of the nasal airways.

A Review of the Mechanism of Vascular Endothelial Injury in Immunoglobulin A Vasculitis

Immunoglobulin A (IgA) vasculitis (IgAV), also known as Henoch-Schönlein purpura, is the most common form of childhood vasculitis. It is characterized by cutaneous hemorrhage, resulting from red blood cell leakage into the skin or mucosae, possibly caused by damage to small blood vessels. These acute symptoms usually disappear without treatment. Endothelial cells are distributed on the inner surfaces of blood vessels and lymphatic vessels, and have important functions in metabolism and endocrine function, as well as being the primary targets of external stimuli and endogenous immune activity. Injury to endothelial cells is a feature of IgA vasculitis. Endothelial cell damage may be related to the deposition of immune complexes, the activation of complement, inflammatory factors, and chemokines, oxidative stress, hemodynamics, and coagulation factors. Both epigenetic mechanisms and genetic diversity provide a genetic background for endothelial cell injury. Here, research on the role of endothelial cells in allergic IgA vasculitis is reviewed.

Effect of ethanolic extract of Rosa centifolia against doxorubicin induced nephrotoxicity in albino rats

BACKGROUND

Efficacy of Anthracycline derivative Doxorubicin (Dox) has been proven in several malignancies such as breast cancer, Hodgkin and non-Hodgkin lymphoma, acute leukemia, lung, thyroid and ovarian cancer. However its clinical usefulness is restricted due to its cardiotoxicity and nephrotoxicity. Rosa centifolia belongs to family Rosaceae and in Ayurveda it is claimed for use in renal disorders. The main phyto-constituents of the plant are terpenoids, glycosides, flavonoids, tannins, phenolic compounds, pro-antroocyanides, pectin and riboflavin.

OBJECTIVE

To investigate the ameliorative role of ethanolic extract of petals of R. centifolia in doxorubicin induced nephrotoxicity in rats.

MATERIALS AND METHODS

Nephrotoxicity was produced by administration of doxorubicin (2.5 mg/kg b.w., i.p. alternate day) in six equal injections for two weeks to achieve a cumulative concentration of 15 mg/kg. Low (LERC - 100 mg/kg p.o.) and high (HERC - 200 mg/kg p.o.) dosees of ethanolic extract of petals of R. centifolia was administered as a pretreatment prior to doxorubicin administration. The general parameters such as body weight, food and water intake were measured throughout the study period. Serum biomarkers such as blood urea nitrogen (BUN), serum creatinine and albumin were measured before treatment and at the end of the experiments. Anti-oxidant enzymes such as glutathione (GSH), melonldehyde (MDA), catalase (CAT) and superoxide dismutase (SOD) were monitored after the last dose. Nephrotoxicity was assessed through histopathological analysis.

RESULTS

The repeated administration of doxorubicin produces several morphological changes including reduction in the body weight as well as decreased food and water consumption. Serum biomarkers such as BUN, serum creatinine were increased and albumin concentration was decreased. The GSH, SOD and CAT concentrations were decreased, whereas MDA concentration was increased. Deteriorating changes in the histological architecture of kidney tissue were observed. In the LERC and HERC pretreated groups following changes were observed in dose dependent manner: increase in body weight, food and water intake (p < 0.05 and p < 0.01), decrease in the BUN (p < 0.05 and p < 0.01) and serum creatinine (p < 0.05 and p < 0.05) concentrations respectively. The significant increase in the albumin (p < 0.01) concentration was observed only in HERC. The pretreatment with LERC and HERC increased the antioxidant enzymes concentrations i.e. GSH (p < 0.01 and p < 0.01), SOD (p < 0.01 and p < 0.01), CAT (p < 0.05 and p < 0.01) and decreased the MDA concentration (p < 0.05 and p < 0.01) respectively. Histopathological studies showed that the pretreatment with low and high doses of ethanolic extract of petals of Rosa centifolia LERC and HERC groups minimized the tubular damage and reduced the inflammation as compared to doxorubicin treated group.

CONCLUSION

The biochemical and histopathological data from the present study clearly support the nephroprotective effect of ethanolic extract of petals of R. centifolia, which might be credited to its anti-oxidant property.

Leaves of Lavender Protect Adult Mice from Hydrogen Peroxide-induced Injury: Evidence fromin vitro and in vivo Tests

Medicinal plants and their secondary metabolites have long been a rich source of biologically active compounds that can prevent many diseases. In this context, we investigated the antioxidant activities of the essential oil of Lavandula officinalis and tested its potency against hepatic and renal toxicity induced by hydrogen peroxide in adult male mice based on measurements of biochemical parameters, oxidative stress, and tissue damage in both organs. We proved a remarkable antioxidant power of this plant (in vitro) by correcting the harmful effects of the prooxidant (in vivo). It can be concluded that lavender is an aromatic plant capable of reducing the stress caused by reactive oxygen species.

A Multiplatform Approach for the Discovery of Novel Drug-Induced Kidney Injury Biomarkers

Drug-induced kidney injury (DIKI) is a common toxicity observed in pharmaceutical development. We demonstrated the use of label-free liquid chromatography-mass spectrometry (LC-MS) and multiplex liquid chromatography-single reaction monitoring (LC-SRM) as practical extensions of standard immunoassay based safety biomarker assessments for identification of new toxicity marker candidates and for improved mechanistic understanding. Two different anticancer drugs, doxorubicin (DOX) and cisplatin (cis-diamminedichloridoplatinum, CDDP), were chosen as the toxicants due to their different modes of nephrotoxicity. Analyses of urine samples from toxicant treated and untreated rats were compared to identify biochemical analytes that changed in response to toxicant exposure. A discovery (label-free LC-MS) and targeted proteomics (multiplex LC-SRM) approach was used in combination with well established immunoassay experiments for the identification of a panel of urinary protein markers related to drug induced nephrotoxicity in rats. The initial generation of an expanded set of markers was accomplished using the label-free LC-MS discovery screen and ELISA based analysis of six nephrotoxicity biomarker proteins. Diagnostic performance of the expanded analyte set was statistically compared to conventional nephrotoxicity biomarkers. False discovery rate (FDR) analysis revealed 18 and 28 proteins from the CDDP and DOX groups, respectively, exhibiting significant differences between the vehicle and treated groups. Multiplex SRM assays were constructed to more precisely quantify candidate markers selected from the discovery screen and immunoassay experiments. To evaluate the sensitivity and specificity for each of the candidate biomarkers, histopathology severity scores were used as a benchmark for renal injury followed by receiver-operating characteristic (ROC) curve analysis on selected biomarkers. Further examination of the best performing analytes revealed relevant biological significance after consideration of anatomical localization and functional roles. In summary, the inclusion of mass spectrometry together with conventional ELISA based assays resulted in the identification of an expanded set of biomarkers with a realistic potential for providing additional beneficial information in mechanistic investigations of drug induced kidney injury and with similar responsiveness to conventionally applied indicators of renal injury.

Targeting Iron Homeostasis in Acute Kidney Injury

Iron is an essential metal involved in several major cellular processes required to maintain life. Because of iron's ability to cause oxidative damage, its transport, metabolism, and storage is strictly controlled in the body, especially in the small intestine, liver, and kidney. Iron plays a major role in acute kidney injury and has been a target for therapeutic intervention. However, the therapies that have been effective in animal models of acute kidney injury have not been successful in human beings. Targeting iron trafficking via ferritin, ferroportin, or hepcidin may offer new insights. This review focuses on the biology of iron, particularly in the kidney, and its implications in acute kidney injury.

The serine protease inhibitor camostat mesilate attenuates the progression of chronic kidney disease through its antioxidant effects

BACKGROUND/AIMS

We have so far demonstrated the renoprotective effect of camostat mesilate (CM) in 5/6 nephrectomized rats at least partly through its antioxidant effect. However, precise mechanisms were not fully clarified. Therefore, we now examined the renoprotective and antioxidant mechanisms of CM by using the adenine-induced chronic kidney disease (CKD) rat model.

METHODS

In protocol 1, we analyzed the effect of CM on CKD. Rats were fed on a 0.75% adenine diet for 3 weeks to induce CKD followed by the experimental period with vehicle, CM, or hydralazine (HYD) treatment for 5 weeks. In protocol 2, we examined the safety of CM and HYD on the normal rats. In addition, we explored free radical scavenging activities of CM and its metabolites in vitro using electron paramagnetic resonance (EPR) spectroscopy.

RESULTS

CM, but not HYD, significantly reduced the serum creatinine levels, although both treatments showed similar reduction in the blood pressure. CM decreased mRNA expression and protein levels of fibrotic markers, the severity of renal fibrosis, the accumulation of oxidative stress, and the expression of NADPH oxidase components in the kidney. In the protocol 2, there were no statistically significant differences in general parameters except for the systolic blood pressure in HYD group. EPR study revealed that CM and its metabolites have potent hydroxyl radical scavenging activities in vitro.

CONCLUSION

Our findings indicate that CM significantly ameliorates the progression of CKD partly through its antioxidant effect independently from its blood pressure-lowering effect. Our results suggest the possibility that CM could be a new therapeutic agent that could arrest the progression of CKD.

Platelets in inflammation: regulation of leukocyte activities and vascular repair

There is now a large body of evidence that platelets are central actors of inflammatory reactions. Indeed, platelets play a significant role in a variety of inflammatory diseases. These diseases include conditions as varied as atherosclerosis, arthritis, dermatitis, glomerulonephritis, or acute lung injury. In this context, one can note that inflammation is a convenient but imprecise catch-all term that is used to cover a wide range of situations. Therefore, when discussing the role of platelets in inflammation, it is important to clearly define the pathophysiological context and the exact stage of the reaction. Inflammatory reactions are indeed multistep processes that can be either acute or chronic, and their sequence can vary greatly depending on the situation and organ concerned. Here, we focus on how platelets contribute to inflammatory reactions involving recruitment of neutrophils and/or macrophages. Specifically, we review past and recent data showing that platelets intervene at various stages of these reactions to regulate parameters such as endothelial permeability, the recruitment of neutrophils and macrophages and their effector functions, as well as inflammatory bleeding. The mechanisms underlying these various modulating effect of platelets are also discussed.

Determination of relative Notch1 and gamma-secretase-related gene expression in puromycin-treated microdissected rat kidneys

Notch signaling pathways are involved in the regulation of cell differentiation and are highly conserved across species. Notch ligand binding leads to gamma-secretase-mediated proteolytic cleavage of the Notch receptor releasing the Notch intracellular domain, resulting in its subsequent translocation into the nucleus and gene expression regulation. To investigate the level of expression of Notch signaling pathway components in microanatomic regions following renal injury, kidneys from untreated, vehicle control, and puromycin aminonucleoside (PA, 150 mg/kg)-treated rats were evaluated. Frozen tissue sections from rats were microdissected using laser capture microdissection (LCM) to obtain glomeruli, cortical (proximal) tubules, and collecting ducts, and relative gene expression levels of Presenilin1, Notch1 and Hes1 were determined. In untreated rats, the Notch1 expression in glomeruli was higher than in the proximal tubules and similar to that in collecting ducts, whereas Presenilin1 and Hes1 expressions were highest in the collecting ducts, followed by cortical tubules and glomeruli. Following PA-induced renal injury, Hes1 gene expression increased significantly in the glomeruli and tubules compared to the collecting ducts where no injury was observed microscopically. Although these data present some evidence of change in Notch signaling related to injury, the expression of Presenilin1, Notch1, and Hes1 in the microanatomic regions of the kidney following PA treatment were not significantly different when compared to controls. These results demonstrate that there are differences in Notch-related gene expression in the different microanatomic regions of the kidneys in rats and suggest a minimal role for Notch in renal injury induced by PA. In addition, this work shows that LCM coupled with the RT-PCR can be used to determine the relative differences in target gene expression within regions of a complex organ.

Urgent call for reconsideration of chronic kidney disease

Circulating toxins namely: free radicals, cytokines and metabolic products induce glomerular endothelial dysfunction, hemodynamic maladjustment and chronic ischemic state;this leads to tubulointerstitial fibrosis in chronic kidney disease (CKD). Altered vascular homeostasis observed in late stage CKD revealed defective angiogenesis and impaired nitric oxide production explaining therapeutic resistance to vasodilator treatment in late stage CKD. Under current practice, CKD patients are diagnosed and treated at a rather late stage due to the lack of sensitivity of the diagnostic markers available. This suggests the need for an alternative therapeutic strategy implementing the therapeutic approach at an early stage. This view is supported by the normal or mildly impaired vascular homeostasis observed in early stage CKD. Treatment at this early stage can potentially enhance renal perfusion, correct the renal ischemic state and restore renal function. Thus, this alternative therapeutic approach would effectively prevent end-stage renal disease.

Effect of a serine protease inhibitor on the progression of chronic renal failure

The number of the chronic renal failure (CRF) patients is increasing explosively. Hypertension, proteinuria, inflammation, fibrosis, and oxidative stress are intertwined in a complicated manner that leads to the progression of CRF. However, the therapeutic strategies to delay its progression are limited. Since serine proteases are involved in many processes that contribute to these risk factors, we investigated the effects of a synthetic serine protease inhibitor, camostat mesilate (CM), on the progression of CRF in 5/6 nephrectomized (Nx) rats. Eighteen male Sprague-Dawley rats were divided into three groups: a sham-operated group ( n = 6), a vehicle-treated Nx group ( n = 6), and a CM-treated Nx group ( n = 6). Following the 9-wk study period, both proteinuria and serum creatinine levels were substantially increased in the vehicle-treated Nx group, and treatment with CM significantly reduced proteinuria and serum creatinine levels. The levels of podocyte-associated proteins in glomeruli, such as nephrin and synaptopodin, were markedly decreased by 5/6 nephrectomy, and this was significantly ameliorated by CM. CM also suppressed the levels of inflammatory and fibrotic marker mRNAs including transforming growth factor-β1, TNF-α, collagen types I, III, and IV, and reduced glomerulosclerosis, glomerular hypertrophy, and interstitial fibrosis in histological studies. Furthermore, CM decreased the expression of NADPH oxidase component mRNAs, as well as reactive oxygen species generation and advanced oxidative protein product levels. Our present results strongly suggest the possibility that CM could be a useful therapeutic agent against the progression of CRF.

Protective Effect of Propolis Ethanol Extract on Ethanol-Induced Renal Toxicity: Anin VivoStudy

Acute p.o. administration of absolute ethanol (10 ml/kg) to fasted mice would produce extensive renal failure. Pretreatment with p.o. administration of propolis ethanol extract (PEE) could prevent such renal failure effectively and dose dependently. This renal protective effect of PEE may be contributed, at least in part, to its antioxidative activity. The maximal antioxidative effect against absolute ethanol (AE)-induced renal failure could be observed 1 hour after PEE administration. In order to further investigate the renal protective mechanism of PEE, lipid peroxidation and superoxide scavenging activity were conducted in vivo. PEE exhibited dose-dependent antioxidative effects on lipid peroxidation in mice renal homogenate. Results indicated that mice with acute renal failure have higher malonic dialdehyde (MDA) levels compared with those in PEE administered mice. It was concluded that the renal protective mechanism of PEE could be contributed, at least in part, to its prominent superoxide scavenging effect; hence, it could protect, indirectly, the kidney from superoxide-induced renal damages.

Modulatory effects of non-steroidal anti-inflammatory drugs on the luminol and lucigenin amplified chemiluminescence of equine neutrophils

The purpose of this study was to explore the potential modulation of equine neutrophil oxidative burst by a series of classical NSAIDs which was subsequently monitored by the luminol or lucigenin-enhanced chemiluminescence (CL) technique. A significant dose-dependent inhibition of the luminol CL was observed with the majority of investigated drugs. This inhibition was very significant for phenylbutazone and Indomethacin; while for aspirin, a higher concentration is required. The action of Ketoprofen was significant during the first 5 min and only when the concentration was above 1 mM. Indomethacin and acetylsalicylic acid result in an inhibition dose-dependent of luminol CL. On the other hand, the phenylbutazone showed an inhibiting effect when used either luminol or lucigenin though luminol is slightly better. When the ketoprofen is considered, an inhibiting effect of luminal CL was observed but less significant than the other NSAIDs investigated. The flunixin meglumine enhances strongly the CL.

Correlation between Oxidative Stress and Thyroid Function in Patients with Nephrotic Syndrome

Background. The present study is to look for a correlation between oxidative stress and thyroid function in patients with the nephrotic syndrome in the remission phase as well as in a persistent proteinuric state. Introduction. Nephrotic syndrome is a form of chronic kidney disease due to which blood loses protein through the urine. We wanted to know if there was an increased loss of thyroid hormones in urine affecting thyroid function. Methods. 60 patients with nephrotic syndrome and 20 healthy non-proteinuric individuals as control subjects were enrolled in the study. We measured their serum tri-iodothyronine, thyroxine and thyroid-stimulating hormone. Estimation of lipid peroxidation (LPx) catalase, superoxide dismutase (SOD), and Glutathione peroxidase (GPx) were carried out by standard methods. Results. TSH was elevated in the nephrotic patients compared to controls, while TT4 and TT3 were significantly lower in the patients than in controls. Lipid Peroxidation and GPx were significantly higher in the nephrotic syndrome patients than in the controls, while SOD and catalase were significantly lower than in patients than in the control subjects. Conclusion. Nephrotic patients can lose significant amounts of thyroid hormones along with protein in urine, which can affect thyroid status, but this is reversible on remission.

High glucose concentration affects the oxidant-antioxidant balance in cultured mouse podocytes

Hyperglycemia is well-recognized and has long-term complications in diabetes mellitus and diabetic nephropathy. In podocytes, the main component of the glomerular barrier, overproduction of reactive oxygen species (ROS) in the presence of high glucose induces dysfunction and increases excretion of albumin in urine. This suggests an impaired antioxidant defense system has a role in the pathogenesis of diabetic nephropathy. We studied expression of NAD(P)H oxidase subunits by Western blotting and immunofluorescence and the activities of the oxidant enzyme, NAD(P)H, and antioxidant enzymes, superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT), in mouse podocytes cultured in a high glucose concentration (30  mM). We found long-term (3 and 5 days) exposure of mouse podocytes to high glucose concentrations caused oxidative stress, as evidenced by increased expression of Nox4 and activities of NAD(P)H oxidase (Δ 182%) and SOD (Δ 39%) and decreased activities of GPx (Δ -40%) and CAT (Δ -35%). These biochemical changes were accompanied by a rise in intracellular ROS production and accumulation of hydrogen peroxide in extracellular space. The role of Nox4 in ROS generation was confirmed with Nox4 siRNA. In conclusion, high glucose concentration affects the oxidant-antioxidant balance in mouse podocytes, resulting in enhanced generation of superoxide anions and its attenuated metabolism. These observations suggest free radicals may play an important role in the pathogenesis of diabetic nephropathy.

Experimental depression induces renal oxidative stress in rats

Depression has been associated to inflammatory and oxidative events. Previous report has shown renal oxidative stress in patients with depression. In order to analyze if depressive status is related to renal oxidative and inflammatory events, Sprague Dawley rats were submitted to forced swimming test (FST) and the renal oxidative metabolism, monocyte-macrophage infiltration and Angiotensin II (Ang II) expression were determined. Rats were submitted to FST daily (30 min) for 15 days. Motor activity was analyzed before FST. Kidney sections were homogenized to measure nitric oxide (NO), malondialdehyde (MDA), reduced glutathione (GSH) and catalase activity by enzymatic and biochemical methods. Renal frozen sections were studied for superoxide anion (O2-), monocyte/macrophage infiltration and Ang II expression by histochemical and immunofluorescence methods. In addition, three groups of FST rats were treated with losartan, sertraline or water for 18 days with further renal O2-analysis. In the FST group, struggle time, motor activity, food intake and body weight gain were found decreased. Increased number of glomerular, interstitial and tubular O2-positive cells was observed in FST rats. High renal content of nitrite/nitrate (NO), MDA and decreased amount of GSH were found in FST rats. Values of renal ED-1 or Ang II positive cells in FST rats remained similar to controls; however, AT1 receptor blocking (losartan) and sertraline reduced both depressive-like behavior and renal O2-expression. These data suggests that depression-like behavior in rats is involved in kidney oxidative stress probably mediated by AT1 receptors.

Doxorubicin induced nephrotoxicity: protective effect of nicotinamide

Introduction. Nephrotoxicity is one of the important side effects of anthracycline antibiotics. The aim of this study was to investigate the effects of nicotinamide (NAD), an antioxidant agent, against nephrotoxicity induced by doxorubicin (DXR). Methods. The rats were divided into control, NAD alone, doxorubicin (20 mg/kg, i.p.) and DXR plus NAD (200 mg/kg, i.p.) groups. At the end of the 10th day, kidney tissues were removed for light microscopy and analysis. The level of tissues' catalase (CAT), glutathione (GSH), glutathione peroxidase (GPx), inducible nitric oxide (iNOS) and endothelial nitric oxide (eNOS) activities were determined. Results. The activities of CAT, GPx, and GSH were decreased, and Po was increased in renal tissue of doxorubicin group compared with other groups. The tissue of the doxorubicin group showed some histopathological changes such as glomerular vacuolization and degeneration, adhesion to Bowman's capsule and thickening and untidiness of tubular and glomerular capillary basement membranes. Histopathological examination showed that NAD prevented partly DXR-induced tubular and glomerular damage. Conclusions. Pretreatment with NAD protected renal tissues against DXR-induced nephrotoxicity. Preventive effects of NAD on these renal lesions may be via its antioxidant and anti-inflammatory action.

Failure of regulation results in an amplified oxidation burst by neutrophils in children with primary nephrotic syndrome

The mechanism responsible for proteinuria in non-genetic idiopathic nephrotic syndrome (iNS) is unknown. Animal models suggest an effect of free radicals on podocytes, and indirect evidence in humans confirm this implication. We determined the oxidative burst by blood CD15+ polymorphonucleates (PMN) utilizing the 5-(and-6)-carboxy-2',7'-dichlorofluorescin diacetate (DCF-DA) fluorescence assay in 38 children with iNS. Results were compared with PMN from normal subjects and patients with renal pathologies considered traditionally to be models of oxidative stress [six anti-neutrophil cytoplasmic autoantibody (ANCA) vasculitis, seven post-infectious glomerulonephritis]. Radicals of oxygen (ROS) production was finally determined in a patient with immunodeficiency, polyendocrinopathy, enteropathy X-linked (IPEX) and in seven iNS children after treatment with Rituximab. Results demonstrated a 10-fold increase of ROS production by resting PMN in iNS compared to normal PMN. When PMN were separated from other cells, ROS increased significantly in all conditions while a near-normal production was restored by adding autologous cells and/or supernatants in controls, vasculitis and post-infectious glomerulonephritis but not in iNS. Results indicated that the oxidative burst was regulated by soluble factors and that this regulatory circuit was altered in iNS. PMN obtained from a child with IPEX produced 100 times more ROS during exacerbation of clinical symptoms and restored to a near normal-level in remission. Rituximab decreased ROS production by 60%. In conclusion, our study shows that oxidant production is increased in iNS for an imbalance between PMN and other blood cells. Regulatory T cells (Tregs) and CD20 are probably involved in this regulation. Overall, our observations reinforce the concept that oxidants deriving from PMN are implicated in iNS.

Increased Oxidative Stress in the Mouse Adriamycin Model of Glomerulosclerosis Is Accompanied by Deposition of Ferric Iron and Altered GGT Activity in Renal Cortex

Chronic renal failure evolves inevitable towards glomerular and tubulo-interstitial sclerosis. This pathological process involves a disturbed redox status of the kidney tissue, leading to irreversible damage. In this study we investigate in an adriamycin model of chronic renal failure in mice the evolution of in vivo hydrogen peroxide production, and the possible role of gamma-glutamyl transpeptidase and ferric iron in the process. Histological changes and ferric iron deposits are evaluated by histochemical staining. To evaluate oxidative stress residual catalase activity, TBARS formation and gamma-glutamyl transpeptidase activity are measured spectrophotometrically. While catalase activity remains the same, a decreased residual catalase activity indicates an increased formation of hydrogen peroxide. Both the activity of gamma-glutamyl transpeptidase and TBARS formation is increased at early stages of the disease. Ferric iron is clearly present in the proximal tubule. Twenty days after adriamycin injection all parameters decrease, probably due to the destruction of the tissue. Our data show the involvement of oxidative stress in the progression of adriamycin induced renal failure in mice. Both radical production and oxidative damage are measurable, while the altered activity of gamma-glutamyl transpeptidase and the deposition of ferric iron suggest the involvement of these factors in the development of a disturbed redox status in the kidney cortex.

Inducible rodent models of acquired podocyte diseases

Glomerular diseases remain the leading cause of chronic and end-stage kidney disease. Significant advances in our understanding of human glomerular diseases have been enabled by the development and better characterization of animal models. Diseases of the glomerular epithelial cells (podocytes) account for the majority of proteinuric diseases. Rodents have been extensively used experimentally to better define mechanisms of disease induction and progression, as well as to identify potential targets and therapies. The development of podocyte-specific genetically modified mice has energized the research field to better understand which animal models are appropriate to study acquired podocyte diseases. In this review we discuss inducible experimental models of acquired nondiabetic podocyte diseases in rodents, namely, passive Heymann nephritis, puromycin aminonucleoside nephrosis, adriamycin nephrosis, liopolysaccharide, crescentic glomerulonephritis, and protein overload nephropathy models. Details are given on the model backgrounds, how to induce each model, the interpretations of the data, and the benefits and shortcomings of each. Genetic rodent models of podocyte injury are excluded.

Oxidants in chronic kidney disease

Chronic kidney disease is a worldwide public health problem that affects approximately 10% of the US adult population and is associated with a high prevalence of cardiovascular disease and high economic cost. Chronic renal insufficiency, once established, tends to progress to end-stage kidney disease, suggesting some common mechanisms for ultimately causing scarring and further nephron loss. This review defines the term reactive oxygen metabolites (ROM), or oxidants, and presents the available experimental evidence in support of the role of oxidants in diabetic and nondiabetic glomerular disease and their role in tubulointerstitial damage that accompanies progression. It concludes by reviewing the limited human data that provide some proof of concept that the observations in experimental models may be relevant to human disease.

Vitamin E in renal therapeutic regiments

Administration of vitamin E in children with immunoglobulin A (IgA) nephropathy, focal segmental glomerulosclerosis (FSGS) and type I diabetes demonstrated potential towards ameliorating progression. Oral vitamin E therapy reduced endothelial dysfunction, lipid peroxidation and oxidative stress in patients with chronic kidney failure (CKF). Moreover, the use of vitamin E-bonded hemodialyzers reduced atherosclerotic changes, erythropoietin dosage and muscular cramps in patients on hemodialysis (HD). However, several controlled clinical trials failed to document beneficial effects on the study subjects' cardiovascular and renal outcomes. A recent report of increased all-cause mortality in adult patients receiving high dose vitamin E therapy has caused considerable concern and debate. These issues regarding the efficacy and safety of vitamin E in renal therapeutic regimens will be reviewed in this article.

Modulating the Progression in IgA Nephropathy

IgA nephropathy affects almost 1% of the population and yet the diagnosis is often missed. This significant kidney disease is often progressive with 25% of the patients going on to end-stage kidney disease over the course of 25 years. This minireview describes the clinical presentations in children and young adults. Therapeutic options are discussed including angiotensin-converting enzyme blockade, steroids, cytotoxics, tonsillectomy, fish oil, vitamin E, singly or in combination, in order to modulate the rate of progression.

Tempol reduces oxidative stress and restores renal dopamine D1-like receptor- G protein coupling and function in hyperglycemic rats

Dopamine via activation of renal D1-like receptors inhibits the activities of Na-K-ATPase and Na/H exchanger and subsequently increases sodium excretion. Decreased renal dopamine production and sodium excretion are associated with hyperglycemic conditions. We have earlier reported D1-like receptor-G protein uncoupling and reduced response to D1-like receptor activation in streptozotocin (STZ)-treated hyperglycemic rats (Marwaha A, Banday AA, and Lokhandwala MF. Am J Physiol Renal Physiol 286: F451-F457, 2004). The present study was designed to test the hypothesis that oxidative stress associated with hyperglycemia increases basal D1-like receptor serine phosphorylation via activation of the PKC-G protein receptor kinase (GRK) pathway, resulting in loss of D1-like receptor-G protein coupling and function. We observed that STZ-treated rats exhibited oxidative stress as evidenced by increased lipid peroxidation. Furthermore, PKC activity and expression of PKC-betaI- and -delta-isoforms were increased in STZ-treated rats. In addition, in STZ-treated rats there was increased GRK2 translocation to proximal tubular membrane and increased basal serine D1-like receptor phosphorylation. Supplementation with the antioxidant tempol lowered oxidative stress in STZ-treated rats, led to normalization of PKC activity, and prevented GRK2 translocation. Furthermore, tempol supplementation in STZ-treated rats restored D1-like receptor-G protein coupling and inhibition of Na-K-ATPase activity on D1-like receptor agonist stimulation. The functional consequence was the restoration of the natriuretic response to D1-like receptor activation. We conclude that oxidative stress associated with hyperglycemia causes an increase in activity and expression of PKC. This leads to translocation of GRK2, subsequent phosphorylation of the D1-like receptor, its uncoupling from G proteins and loss of responsiveness to agonist stimulation.

Superoxide dismutase mimetic preserves the glomerular capillary permeability barrier to protein

Overproduction of superoxide (O2*) occurs in glomerular disease and may overwhelm the capacity of superoxide dismutase (SOD), thereby intensifying oxidant injury by O2* and related radical species that disrupt the glomerular capillary permeability barrier to protein. We examined the efficacy of the SOD mimetic tempol in preserving glomerular permeability to protein using 1) a rat model of glomerular immune injury induced by an antiglomerular basement membrane antibody (anti-GBM), and 2) isolated rat glomeruli in which injury was induced by the cytokine tumor necrosis factor-alpha (TNFalpha). To induce glomerular immune injury, rats received anti-GBM using a protocol that results in prominent infiltration of glomeruli by macrophages and in which macrophage-derived TNFalpha has been shown to mediate albuminuria. To increase glomerular capillary permeability to albumin (P(alb)) ex vivo, isolated glomeruli were incubated with TNFalpha at concentrations (0.5-4.0 microg/ml) known to stimulate O2* production. Increments in P(alb) were detected by measuring changes in glomerular volume in response to an applied oncotic gradient. Significant increases in the urine excretion of albumin and F(2alpha)-isoprostane were observed in rats with glomerular immune injury without a significant change in systolic blood pressure. Tempol treatment significantly reduced urine isoprostane and albumin excretion. In isolated glomeruli, TNFalpha increased P(alb) and tempol abrogated this effect, both in a dose-dependent manner. These observations indicate that SOD mimetics can preserve the glomerular permeability barrier to protein under conditions of oxidative stress from O2* production.

Puromycin-based purification of rat brain capillary endothelial cell cultures. Effect on the expression of blood-brain barrier-specific properties

One of the main difficulties with primary rat brain endothelial cell (RBEC) cultures is obtaining pure cultures. The variation in purity limits the achievement of in vitro models of the rat blood-brain barrier. As P-glycoprotein expression is known to be much higher in RBECs than in any contaminating cells, we have tested the effect of five P-glycoprotein substrates (vincristine, vinblastine, colchicine, puromycin and doxorubicin) on RBEC cultures, assuming that RBECs would resist the treatment with these toxic compounds whereas contaminating cells would not. Treatment with either 4 microg/mL puromycin for the first 2 days of culture or 3 microg/mL puromycin for the first 3 days showed the best results without causing toxicity to the cells. Transendothelial electrical resistance was significantly increased in cell monolayers treated with puromycin compared with untreated cell monolayers. When cocultured with astrocytes in the presence of cAMP, the puromycin-treated RBEC monolayer showed a highly reduced permeability to sodium fluorescein (down to 0.75 x 10(-6) cm/s) and a high electrical resistance (up to 500 Omega x cm(2)). In conclusion, this method of RBEC purification will allow the production of in vitro models of the rat blood-brain barrier for cellular and molecular biology studies as well as pharmacological investigations.

Effects of Simvastatin on Oxidative Stress in Streptozotocin-Induced Diabetic Rats: A Role for Glomeruli Protection

AIMS

To study the effects of simvastatin on oxidative stress in rats with early stage diabetic nephropathy.

METHODS

60 male Sprague-Dawley rats were divided into three groups: control group (CN), streptozotocin (STZ)-induced diabetic rats group (DM) and STZ-induced diabetic rats group treated with simvastatin (DM+S). The following parameters were measured at weeks 6 and 12 in similar rats chosen randomly from each group: body and kidney weight, 24-hour urinary albumin excretion (UAE), biochemical indexes including blood glucose (GLU), low-density lipoprotein (LDL), high-density lipoprotein (HDL), triglycerides (TG), serum creatinine (SCr), antioxidant enzymes including superoxide dismutase (SOD), glutathione S-transferase (GST), catalase (CAT) in plasma, lipid peroxidation production as malondialdehyde in plasma (MDAp) and erythrocytes (MDAe), morphology parameters such as glomerular volume (GV) and mesangial area/total glomerular area (M/T).

RESULTS

At weeks 6 and 12, GLU and kidney weight to body weight ratio were notably increased in both of the diabetic groups compared with those in the CN group without significant differences between the two diabetic groups. There were no significant differences of SCr, LDL, HDL and TG among all groups within all the experimental time. MDAp and MDAe were significantly increased in both of the diabetic groups, especially at week 12, while SOD, GST and CAT were significantly decreased compared with those in the CN group. At week 12, GV, M/T and UAE were also increased in the two diabetic groups. However, in the DM+S group, changes of lipid peroxidation production, antioxidant enzymes, UAE and GV were less pronounced than those in the DM group. Pearson's correlation analysis and regression analysis shown that MDAp was increased while SOD, GST and CAT in plasma were decreased with elevation of UAE, GV and M/T.

CONCLUSION

Increased lipid peroxidation and decreased antioxidant enzymes in plasma may play a role in the progression of diabetic nephropathy. Simvastatin may ameliorate these changes to protect kidney from oxidative lesion in diabetes even in the absence of lipid abnormalities.

Assessment of oxidative stress in the early posttransplant period: comparison of cyclosporine A and tacrolimus-based regimens

BACKGROUND

Oxidative stress is one of the leading causes of cardiovascular morbidity and mortality in chronic kidney disease. Although it is clear that many metabolic abnormalities improve, the effects of kidney transplantation on oxidative state are obscure.

METHODS

Twenty-three kidney transplant patients were included in the study. Eleven patients (mean age 27.9+/- 9.1 years) were treated with cyclosporine A (CsA) whereas 12 patients (mean age 22.4 +/- 3.4 years) were treated with tacrolimus. Twenty-three healthy subjects served as controls. None of the patients or controls suffered from diabetes mellitus or an acute infection at the time of the study. Plasma malondialdehyde (MDA), plasma selenium (Se), erythrocyte glutathione peroxidase (GSH-Px), erythrocyte superoxide dismutase (SOD), erythrocyte Zn (EZn), and erythrocyte Cu (ECu) levels were studied before and in the 1st, 3rd, 7th, 14th and 28th days after the transplantation.

RESULTS

The GSH-Px, SOD, ECu, EZn and selenium levels were lower and MDA levels were higher in patients than controls before transplantation (p < 0.001 for all). MDA levels decreased and SOD, GSH-Px, ECu, EZn levels increased in parallel to the decrement of serum creatinine levels following the renal transplantation. No difference was found among the patients regarding the treatment regime.

CONCLUSION

The study data suggest that the improvement in oxidative state parameters begins at the first day of renal transplantation and continues at the 28th posttransplant day in living donor transplantations.

Suppressive Effects of Iron on TGF-β1 Production by Renal Proximal Tubular Epithelial Cells

BACKGROUND

TGF-beta1, which is one of the profibrogenic cytokines, is considered essential for both the tubulointerstitial fibrosis found in chronic kidney diseases and the repair of tissue damage in acute renal injury. Iron plays an important part in inflammatory damage since it supplies cytotoxic hydroxyl radicals. The aim of the present study was to examine the direct effects of iron on TGF-beta1 production and the expression of 8-hydroxy-2'-deoxyguanosine (8-OHdG), a marker of oxidative stress, by human renal proximal tubular epithelial cells (RPTEC).

METHODS

Using human RPTEC, TGF-beta1 expression was studied by immunohistochemical staining, ELISA and RNase protection assays. 8-OHdG expression was evaluated by immunohistochemical staining.

RESULTS

Ferric iron suppressed both TGF-beta1 secretion and mRNA expression, and enhanced 8-OHdG expression in RPTEC in a dose-dependent manner. Desferrioxamine, an iron chelator, eliminated the suppressive effect of ferric citrate on TGF-beta1 production.

CONCLUSIONS

The results suggest that iron may delay the repair of kidney injury during the acute inflammatory phase via a reduction in TGF-beta1 production by RPTEC. Iron chelation may therefore be a useful strategy in the treatment of inflammatory kidney diseases.

Oxidants and iron in chronic kidney disease

Oxidants derived either from leukocytes in proliferative glomerular nephritis or from resident glomerular cells in nonproliferative glomerulonephritis have been shown to have several biologic effects relevant to chronic kidney disease. These include: the ability of oxidants to damage glomerular basement membrane (GBM) and to directly induce proteinuria; effects that would lead to a fall in the glomerular filtration rate; and effects that would account for the morphologic changes observed in chronic kidney disease. In experimental models the role of oxidants has been demonstrated in both proliferative glomerulonephritis (e.g., anti-GBM antibody disease) as well as experimental models of minimal change disease and membranous nephropathy. Oxidants have also been shown to be an important mediator of the various pathways that have been implicated in diabetic nephropathy. Antioxidants and iron chelators have also been shown to retard functional and morphologic changes observed in progressive kidney disease. Taken together, these experimental studies suggest an important role of oxidants in chronic kidney disease.

Superoxide scavenging attenuates renal responses to ANG II during nitric oxide synthase inhibition in anesthetized dogs

To assess the role of superoxide (O2−) and nitric oxide (NO) interaction in mediating the renal actions of ANG II, we examined the renal responses to intra-arterial infusion of ANG II (0.5 ng·kg−1·min−1) before and during administration of a superoxide dismutase mimetic, tempol (0.5 mg·kg−1·min−1), in the presence or absence of NO synthase inhibitor, nitro-l-arginine (NLA; 50 μg·kg−1·min−1), in anesthetized dogs pretreated with enalaprilat (33 μg·kg−1·min−1). In one group of dogs ( n = 7), ANG II infusion before tempol infusion caused decreases of 24 ± 4% in renal blood flow (RBF), 55 ± 7% in urine flow (V), and 53 ± 8% in urinary sodium excretion (UNaV) with a slight decrease in glomerular filtration rate (GFR; −7.8 ± 3.4%). Tempol infusion alone did not cause significant alterations in RBF, GFR, V, or UNaV; however, ANG II in the presence of tempol caused a smaller degree of decreases in RBF (−12 ± 2%), in V (−16 ± 5%), and in UNaV (−27 ± 10%) with a slight increase in GFR (6.6 ± 2.8%) than the responses observed before tempol. In another group of NLA-treated dogs ( n = 6), tempol infusion also caused significant attenuation in the ANG II-induced responses on RBF (−13 ± 3% vs. −22 ± 7%), GFR (−19 ± 5% vs. −33 ± 3), V (−15 ± 12% vs. −28 ± 4%), and UNaV (−11 ± 14% vs. −32 ± 7%). These data demonstrate that renal responses to ANG II are partly mediated by O2−generation and its interaction with NO. The sodium-retaining effect of ANG II is greatly influenced by O2−generation, particularly in the condition of NO deficiency.

Cellular oxidative processes in relation to renal disease

This article summarizes the biochemical processes that produce reactive oxygen species (ROS) and other mediators that account for 'oxidative stress'. Formation of ROS in signal transduction cascades is illustrated from studies of kidney cell systems. The pathophysiological implications for the nephrologist are then reviewed.

Tissue kallikrein attenuates salt-induced renal fibrosis by inhibition of oxidative stress

BACKGROUND

High salt intake induces hypertension, cardiac hypertrophy, and progressive renal damage. Progressive renal injury is the consequence of a process of destructive fibrosis. Using gene transfer approach, we have shown that the tissue kallikrein-kinin system (KKS) plays an important role in protection against renal injury in several hypertensive rat models. In this study, we further investigated the effect and potential mechanisms mediated by kallikrein on salt-induced renal fibrosis.

METHODS

Adenovirus harboring the human tissue kallikrein gene was delivered intravenously into Dahl salt-sensitive (DSS) rats on a high salt diet for 4 weeks. Two weeks after gene delivery, the effect of kallikrein on renal fibrosis was examined by biochemical and histologic analysis.

RESULTS

Kallikrein gene delivery resulted in reduced blood urea nitrogen (BUN), urinary protein and albumin levels in DSS rats on a high salt diet. Expression of recombinant human tissue kallikrein was detected in the sera and urine of rats injected with the kallikrein gene. Histologic investigation showed that kallikrein gene delivery significantly reduced glomerular and tubular fibrosis scores and collagen deposition, as well as renal cell proliferation, compared to rats on a high salt diet injected with control virus. Kallikrein gene transfer significantly increased nitric oxide and cyclic guanosine monophosphate (cGMP) levels in conjunction with reduced salt-induced nicotinamide adenine dinucleotide/nicotinamide adenine dinucleotide phosphate (NADH/NADPH) oxidase activity, superoxide production, transforming growth factor-beta1 (TGF-beta1) mRNA and protein levels, and TGF-beta1 immunostaining.

CONCLUSION

These results indicate that tissue kallikrein protects against renal fibrosis in hypertensive DSS rats through increased nitric oxide bioavailability and suppression of oxidative stress and TGF-beta expression.

Caffeic acid phenethyl ester as a protective agent against doxorubicin nephrotoxicity in rats

BACKGROUND

Nephrotoxicity is one of the important side effects of antracycline antibiotics. The aim of this study was to investigate the effects of caffeic acid phenethyl ester (CAPE), an antioxidant agent, against nephrotoxicity induced by doxorubicin (DXR).

METHODS

The rats were divided into control, CAPE alone, doxorubicin (20 mg/kg, i.p.) and doxorubicin plus CAPE (10 micromol/kg/day, i.p.) groups. At the end of the 10th day, kidney tissues were removed for light microscopy and analysis. The levels of tissues protein carbonyl content (PC), malondialdehyde (MDA) and nitric oxide (NO) as well as the activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) and myeloperoxidase (MPO) were determined. Plasma oxidants and antioxidants were also measured.

RESULTS

The activities of CAT and GSH-Px were decreased as well as myeloperoxidase, NO, MDA and PC were increased in renal tissue of doxorubicin group compared with the other groups. Plasma GSH-Px activity was higher in doxorubicin plus CAPE group than the others and plasma MDA level was higher in doxorubicin group than the other groups. There were glomerular vacuolization, tubular desquamation, loss of brush border, and adhesion to Bowman's in the light microscopy in the kidneys of doxorubicin group. The tubules and brush border were almost normal and some of the glomerulus was filled with fine vacuoles in CAPE treated rats.

CONCLUSION

Doxorubicin caused renal injury and CAPE treatment prevented lipid peroxidation and protein oxidation in renal tissue and partially preserved glomerulus and tubules.

Inhibition of nitric oxide synthase enhances superoxide activity in canine kidney

To evaluate the role of a potential interaction between superoxide anion (O2−) and nitric oxide (NO) in regulating kidney function, we examined the renal responses to intra-arterial infusion of a superoxide dismutase mimetic, tempol (0.5 mg·kg−1·min−1), in anesthetized dogs treated with or without NO synthase inhibitor, Nω-nitro-l-arginine (NLA; 50 μg·kg−1·min−1). In one group of dogs ( n = 10), tempol infusion alone for 30 min before NLA infusion did not cause any significant changes in renal blood flow (RBF; 5.2 ± 0.4 to 5.0 ± 0.4 ml·min−1·g−1), glomerular filtration rate (GFR; 0.79 ± 0.04 to 0.77 ± 0.04 ml·min−1·g−1), urine flow (V; 13.6 ± 2.1 to 13.9 ± 2.5 μl·min−1·g−1), or sodium excretion (UNaV; 2.4 ± 0.3 to 2.2 ± 0.3 μmol·min−1·g−1). Interestingly, when tempol was infused in another group of dogs ( n = 12) pretreated with NLA, it caused increases in V (4.4 ± 0.4 to 9.7 ± 1.4 μl·min−1·g−1) and in UNaV (0.7 ± 0.1 to 1.3 ± 0.2 μmol·min−1·g−1) without affecting RBF or GFR. Although NO inhibition caused usual qualitative responses in both groups of dogs, the antidiuretic (47 ± 5 vs. 26 ± 4%) and antinatriuretic (67 ± 4 vs. 45 ± 11%) responses to NLA were seen much less in dogs pretreated with tempol. NLA infusion alone increased urinary excretion of 8-isoprostane (13.9 ± 2.7 to 22.8 ± 3.6 pg·min−1·g−1; n = 7), which returned to the control levels (11.6 ± 3.4 pg·min−1·g−1) during coadministration of tempol. These data suggest that NO synthase inhibition causes enhancement of endogenous O2−levels and support the hypothesis that NO plays a protective role against the actions of O2−in the kidney.

Increased oxidative stress and apoptosis in acute puromycin aminonucleoside nephrosis

Accumulating evidence demonstrates that oxidative stress is one of the underlying mechanisms to induce apoptosis in different biological systems. The aim of this study was to examine the simultaneous presence and correlation between oxidative stress events, apoptosis, apoptosis-associated proteins and monocyte/macrophage infiltration during the course of acute puromycin aminonucleoside nephrosis (PAN). To induce nephrosis, Sprague-Dawley rats were injected intraperitoneally with puromycin aminonucleoside and killed at weeks 1 and 2 of nephrosis. Controls represent animals injected with 0.9% saline solution. Kidney sections were homogenized to measure nitric oxide (NO), malondialdehyde (MDA), reduced glutathione (GSH), superoxide dismutase (SOD) and catalase activities by appropriate enzymatic and biochemical methods. Renal frozen sections were studied for superoxide anion (O(2) (-)) by a histochemical method, for apoptosis by TUNEL (terminal-deoxynucleotidyl-transferase-mediated dUTP- digoxigenin nick end labelling) and for apoptosis-associated protein expression and monocyte/macrophage infiltration by monoclonal antibodies. Increased renal apoptosis, p53, Bax, Bcl-2 accompanied by increased O(2) (-) and NO generation, lipid peroxidation (MDA) and monocyte/macrophage infiltration were found in nephrotic animals. Renal oxidative stress (O(2) (-), NO and MDA) was correlated with apoptosis, p53 expression, monocyte/macrophage cells and proteinuria. Anti-oxidant molecules (SOD and GSH) remained unchanged apart from a decreased activity of catalase which correlated with glomerular apoptosis. In conclusion, the close correlation between the presence of apoptosis and oxidative events confirms the role of oxidative stress in the apoptosis observed during PAN.

Evaluating role of oxidative stress in determining the pathogenesis of falciparum malaria induced acute renal failure

Serum malondialdehyde was measured in sixty-one falciparum malaria cases, which include thirty uncomplicated, and thirty-one complicated with acute renal failure. Twenty-six healthy individuals were also studied as controls. Serum malondialdehyde level was found to be significantly elevated in falciparum malaria induced acute renal failure cases when compared with uncomplicated falciparum malaria (p<0.001) and healthy controls (p<0.001). A positive correlation with the raised urea, creatinine and bilirubin levels were significant (r=0.62, p<0.025; r=0.65, p<0.05 and r=0.72, p<0.001 respectively) indicating the severity of complication with rise of lipid peroxides in falciparum malaria induced acute renal failure cases.

TGF-beta isoforms in renal fibrogenesis

BACKGROUND

Transforming growth factor-beta1 (TGF-beta1) is generally considered to be the major or predominant isoform involved in fibrosis, with the roles of TGF-beta2 and -beta3 being less clear. Because anti-TGF-beta-specific isoform treatment is in development, it is important to know more precisely about isoform action. Here we compared the actions of each isoform on production and degradation of extracellular matrix proteins by cultured rat mesangial cells, renal fibroblasts, and tubular epithelial cells. We investigated endogenous production of each isoform, the effect of adding one isoform on the production of the other isoforms, and the response to addition of isoform combinations on matrix protein production. Isoform-specific antibodies were used to determine the relative contribution of these isoforms to matrix protein production.

METHODS

Each cell type was treated with TGF-beta (0.01 to 10 ng/mL) alone or in different combinations. Living cell number was determined by 3-[4,5]dimethylthiazol-2,5-diphenyltetrazolium bromide (MTT) assay. Supernatant fibronectin and TGF-beta isoform concentration were measured by enzyme-linked immunosorbent assay (ELISA). Collagen and proteoglycan production were measured by [3H]-proline and [35S]-sulfate incorporation, respectively. Matrix protein and TGF-beta isoform gene expression were determined by Northern blot. Release of 3H from preformed radiolabeled matrix by fibroblasts was used as a measure of matrix degradation.

RESULTS

Each isoform increased matrix protein synthesis and reduced matrix degradation by renal cells similarly. Combination of TGF-beta isoforms showed additive effects. No antifibrotic effect was observed with TGF-beta3. TGF-beta1 increased -beta2 and -beta3 production in a small and inconsistent manner. In contrast, TGF-beta2 and -beta3 stimulated TGF-beta1 in all three cell types. Eighty percent of TGF-beta3's fibrogenic effect was mediated by TGF-beta1. A pan-specific antibody to TGF-beta most effectively blocked plasminogen activator inhibitor type 1 (PAI-1) synthesis by epithelial cells under oxidative stress.

CONCLUSION

All three TGF-beta isoforms have fibrogenic effects on renal cells. TGF-beta2 and TGF-beta3 effects may be partially mediated by TGF-beta1. These data suggest that blockade of all isoforms together may yield the best therapeutic effect in reducing renal fibrosis.