Protective effect of apocynin, a NADPH-oxidase inhibitor, against contrast-induced nephropathy in the diabetic rats: A comparison with n-acetylcysteine

Acrolein plays a culprit role in the pathogenesis of diabetic nephropathy in vitro and in vivo

OBJECTIVE

Diabetic nephropathy (DN), also known as diabetic kidney disease (DKD), is a major chronic complication of diabetes and is the most frequent cause of kidney failure globally. A better understanding of the pathophysiology of DN would lead to the development of novel therapeutic options. Acrolein, an α,β-unsaturated aldehyde, is a common dietary and environmental pollutant.

DESIGN

The role of acrolein and the potential protective action of acrolein scavengers in DN were investigated using high-fat diet/ streptozotocin-induced DN mice and in vitro DN cellular models.

METHODS

Acrolein-protein conjugates (Acr-PCs) in kidney tissues were examined using immunohistochemistry. Renin-angiotensin system (RAS) and downstream signaling pathways were analyzed using quantitative RT-PCR and Western blot analyses. Acr-PCs in DN patients were analyzed using an established Acr-PC ELISA system.

RESULTS

We found an increase in Acr-PCs in kidney cells using in vivo and in vitro DN models. Hyperglycemia activated the RAS and downstream MAPK pathways, increasing inflammatory cytokines and cellular apoptosis in two human kidney cell lines (HK2 and HEK293). A similar effect was induced by acrolein. Furthermore, acrolein scavengers such as N-acetylcysteine, hydralazine, and carnosine could ameliorate diabetes-induced kidney injury. Clinically, we also found increased Acr-PCs in serum samples or kidney tissues of DKD patients compared to normal volunteers, and the Acr-PCs were negatively correlated with kidney function.

CONCLUSIONS

These results together suggest that acrolein plays a role in the pathogenesis of DN and could be a diagnostic marker and effective therapeutic target to ameliorate the development of DN.

Dapagliflozin Attenuates Contrast-induced Acute Kidney Injury by Regulating the HIF-1α/HE4/NF-κB Pathway

ABSTRACT

Contrast-induced acute kidney injury (CI-AKI) causes clinically acquired nephropathy in patients who undergo coronary interventions. Hypoxic injury to proximal tubular epithelial cells is a pathological mechanism of CI-AKI. Previous studies have shown that hypoxia activates HIF-1α/HE4/NF-κB to enhance renal fibrosis, and the SGLT-2 inhibitor luseogliflozin inhibits hypoxia-inducible factor (HIF)-1α expression to reduce the progression of diabetic nephropathy. However, the therapeutic effects and mechanisms of SGLT-2 inhibitors on CI-AKI are unclear. We explored the role of the HIF-1α/HE4/NF-κB pathway in CI-AKI and how dapagliflozin effectively treats CI-AKI by inhibiting this pathway. In vitro, cells were divided into the control, hypoxia, hypoxia + dapagliflozin, and hypoxia + pSilencer-HIF-1α groups. Cellular hypoxia, apoptosis, and related protein expression were evaluated by immunofluorescence, western blotting, and flow cytometry, respectively. Dapagliflozin significantly decreased oxygen consumption, HIF-1α, human epididymis protein 4 (HE4), NF-κB expression, and apoptotic cells compared with the control (P < 0.01). In vivo, rats were divided into the control (C), diabetes (D), diabetes + contrast media, and diabetes + contrast media + dapagliflozin groups. Rats in the latter 2 groups were treated with dapagliflozin for 2 days. CI-AKI was induced by intravenously injecting indomethacin, N-nitro-l-arginine methyl ester, and iohexol. The effects of dapagliflozin on CI-AKI rats were elucidated by assessing renal function, H&E staining, and immunohistochemistry. Serum creatinine, urea nitrogen, TUNEL-positive tubular cells, HIF-1α, HE4, NF-κB expression, and histopathological scores were increased in diabetes + contrast media rats compared with C, D, and diabetes + dapagliflozin + contrast media rats (P < 0.01). Thus, dapagliflozin may ameliorate CI-AKI through suppression of HIF-1α/HE4/NF-κB signaling in vitro and in vivo.

Nephroprotective Effect of Coenzyme Q10 alone and in Combination with N-acetylcysteine in Diabetic Nephropathy

Aim

Oxidative stress due to chronic hyperglycaemia is a key factor in the development and progression of various microvascular complications including diabetic nephropathy (DN) and associated renal injury. Treatment with antioxidants is one of the strategies to protect the kidney from oxidative tissue damage to improve renal physiology during DN. The investigation, therefore, was designed to assess the nephroprotective effect of coenzyme Q10 (CoQ10) and N-acetylcysteine (NAC), either alone or in combination in streptozotocin (STZ)-nicotinamide (NAD) induced diabetic nephropathy (DN) in rats.

Methods

T2DM induced by STZ (55 mg/kg, i.p.)-NAD (110 mg/kg, i.p.) in Sprague-Dawley rats (220–250 g) was confirmed by the elevated blood glucose level and glycated haemoglobin. DN was assessed by renal function tests. The diabetic rats were treated with CoQ10 (10 mg/kg, p.o.) and/or NAC (300 mg/kg, p.o.) for 8 weeks after confirmation of DN. Oxidative tissue damage due to STZ-NAD was estimated by malondialdehyde (MDA), superoxide dismutase (SOD) and catalase (CAT), reduced glutathione (GSH), myeloperoxidase (MPO) and nitric oxide (NO) in the renal homogenate.

Results

Data showed significant alteration in serum and urinary creatinine, total protein, albumin, serum urea, blood urea nitrogen (BUN) and uric acid in diabetic animals as compared to the control rats. CoQ10 and/or NAC effectively alleviated the disturbances in renal function. Diabetic rats showed increased MDA, decreased SOD and CAT activities and decreased GSH along with a significant increase in MPO activity and nitrite content. Treatment with the aforementioned antioxidants and their combination ameliorated the kidney damage as indicated by the reduced OS with improved renal function.

Conclusion

The investigation suggests that the chronic hyperglycaemia-induced OS leads to the development and progression of DN. The combined treatment with CoQ10 and NAC has shown a remarkable nephroprotective effect suggesting that combined antioxidant therapy with CoQ10 and NAC may be useful in the attenuation of DN.

Apigenin-Loaded Solid Lipid Nanoparticle Attenuates Diabetic Nephropathy Induced by Streptozotocin Nicotinamide Through Nrf2/HO-1/NF-kB Signalling Pathway

Background

Apigenin is known to have a broad-spectrum efficacy in oxidative stress and conditions due to inflammation, although weak absorption, fast metabolic rate and a fast elimination (systemic) limit the pharmacological efficacy of this drug. Hence, we propose the usage of highly bioavailable Apigenin-solid lipid nanoparticles (SLNPs) to recognize such limitations. The defensive function of Apigenin-SLNPs on renal damage induced by streptozotocin (STZ) in animals was studied.

Materials and Methods

We initially injected the rats with 35 mg kg⁻¹ streptozocin intraperitoneally, and after 7 days, the rats were then injected 150 mg kg⁻¹ of metformin intragastrically followed by a once-daily intragastric dose of Apigenin-SLNP (25 or 50 mg kg⁻¹) for a continuous period of 30 days. We then measured the level of insulin and blood glucose, superoxide dismutase, catalase and malondialdehyde in the tissues of the kidney. We also observed messenger-RNA expression of Interleukin-1β, Interleukin-6 and Tumor Necrosis Factor-alpha in renal tissue through RT-PCR technique. Moreover, H&E staining and Western blotting observed the histopathological variations and protein expression of nuclear factor erythroid 2-related factor 2/heme oxygenase/Nuclear Factor-κB signaling pathway, respectively.

Results

An enhancement in the expressing of nuclear factor erythroid 2-related factor 2 and heme oxygenase-1 and a suppression in the expression of Nuclear Factor-κB occurred due to Apigenin-SLNPs treatment, which was a result of the protective mechanism of Apigenin-SLNPs which is because of not only its anti-inflammatory function (by inhibition of release of inflammatory factors) but also their anti-oxidant activity (through reduction of lipid peroxidation production).

Conclusion

We found that a protective effect on diabetic nephropathy was shown due to Apigenin-SLNPs, in rats induced with streptozocin maybe through the pathway of nuclear factor erythroid 2-related factor 2/heme oxygenase-1/Nuclear Factor-κB.

DDAH-2 alleviates contrast medium iopromide-induced acute kidney injury through nitric oxide synthase

BACKGROUND

Contrast medium-induced acute kidney injury (CI-AKI) is one of the most common causes of hospital-acquired acute renal failure. However, the pathogenesis of CI-AKI remains unclear. Asymmetric dimethylarginine (ADMA) is an endogenous nitric oxide synthase (NOS) inhibitor that is largely metabolised by dimethylarginine dimethylaminohydroxylase (DDAH) in humans. Two isoforms of DDAH exist, namely, DDAH-1 and DDAH-2. In the present study, we examined whether the DDAH-2/ADMA/NOS pathway is involved in the pathogenesis of CI-AKI.

METHODS AND RESULTS

Exposure to the contrast medium iopromide led to increase in creatinine and blood urea nitrogen (BUN) levels, accumulation of ADMA, increase in reactive oxygen species (ROS) generation, and an inflammatory response in mice kidney tissue. The injection of adenovirus-harbouring DDAH-2 lowered renal ADMA levels and had a reno-protective effect against contrast-medium injury by decreasing cell apoptosis, ROS, and fibrosis. By contrast, contrast medium-induced renal injury was exacerbated in heterozygous DDAH-2 knockout mice. In the in vitro study, overexpression of DDAH-2 increased the levels of nitrite and intracellular cGMP, while the DDAH-2 knockdown induced the opposite effect. These findings were also observed in the in vivo sample.

CONCLUSIONS

Our findings provide the first evidence that the DDAH-2/ADMA/NOS pathway is involved in the pathogenesis of CI-AKI and that the protective effect of DDAH-2 probably arises from the modulation of NOS activity, oxidative stress, and the inflammatory process.

The glucagon-like peptide-1 receptor agonist Exendin-4, ameliorates contrast-induced nephropathy through suppression of oxidative stress, vascular dysfunction and apoptosis independent of glycaemia

Contrast-induced nephropathy (CIN) is a leading cause of hospital-acquired acute kidney injury, particularly in diabetic patients. Previous studies have shown renoprotective effects of glucagon-like peptide-1 (GLP-1) signalling; however, its role in CIN remains unexplored. This study investigates the prophylactic effect of exendin-4, a GLP-1R agonist, against CIN in a rat model mimicking both healthy and diabetic conditions. Animals were randomly divided into 7 groups: a control sham group (n = 8), and 2 identical sets of 3 disease groups, one received exendin-4 before exposure to contrast medium (CM), while the other served as untreated control. The 3 disease groups represented diabetes (n = 8), CIN (n = 8), or diabetes and CIN combined (n = 8). Untreated groups showed deteriorating renal function as indicated by significantly higher levels of serum creatinine and blood urea nitrogen, malondialdehyde, and endothelin-1 and caspase-3 expression compared to the sham control group. This was accompanied by a significant decrease in tissue reserves of reduced glutathione, superoxide dismutase, nitrate and endothelin nitric oxide synthase as well as deteriorating renal histology. The CM-induced changes in diabetic rats indicate impaired renal function, oxidative stress, vascular dysfunction, and apoptosis, and were significance higher in intensity compared to non-diabetic rats. Pretreatment with exendin-4 ameliorated all the aforementioned CM-induced nephropathic effects independent of the glycemic state. To our knowledge, this is the first study describing the prophylactic renoprotective effects of exendin-4 against CIN. With the current pharmaceutical use of exendin-4 as a hypoglycaemic agent, the GLP-1R agonist becomes an interesting candidate for human clinical trials on CIN prevention.

The Protective Effects of Enalapril Maleate and Folic Acid Tablets against Contrast-Induced Nephropathy in Diabetic Rats

Background

Renal vasoconstriction, oxidative stress, endothelial dysfunction, and apoptosis are the major causes of contrast-induced nephropathy (CIN). The aim of this study was to evaluate the protective effects of enalapril maleate and folic acid tablets on CIN in diabetic rats.

Methods

Thirty-two Sprague-Dawley rats were divided into four groups: CIN (C), CIN + enalapril maleate (CE), CIN + folic acid (CF), and CIN + enalapril maleate and folic acid tablets (CEF). CE, CF, and CEF rats were treated orally with enalapril maleate, folic acid, or enalapril maleate and folic acid tablets, respectively, for 5 days. CIN was induced in all groups followed by analyzed biochemical parameters, oxidative stress markers, endothelial dysfunction parameters, renal histopathology, and TUNEL staining.

Results

Serum creatinine, blood urea nitrogen, and malondialdehyde levels were lower in the CEF group than in the C group. Homocysteine, superoxide dismutase, glutathione peroxidase, and nitric oxide levels were higher in the CEF group than in the C group. Histopathology scores and percentage of apoptotic kidney cells in the CEF group were significantly decreased compared with those in the C group.

Conclusions

These results suggest that enalapril maleate and folic acid tablets have a protective effect against CIN in diabetic rats.

Oxidative stress caused by activation of NADPH oxidase 4 promotes contrast-induced acute kidney injury

Contrast-induced acute kidney injury (CIAKI) is a leading cause of acute kidney injury following radiographic procedures. Intrarenal oxidative stress plays a critical role in CIAKI. Nicotinamide adenine dinucleotide 3-phosphate (NADPH) oxidases (Noxs) are important sources of reactive oxygen species (ROS). Among the various types of Noxs, Nox4 is expressed predominantly in the kidney in rodents. Here, we evaluated the role of Nox4 and benefit of Nox4 inhibition on CIAKI using in vivo and in vitro models. HK-2 cells were treated with iohexol, with or without Nox4 knockdown, or the most specific Nox1/4 inhibitor (GKT137831). Effects of Nox4 inhibition on CIAKI mice were examined. Expression of Nox4 in HK-2 cells was significantly increased following iohexol exposure. Silencing of Nox4 rescued the production of ROS, downregulated pro-inflammatory markers (particularly phospho-p38) implicated in CIAKI, and reduced Bax and caspase 3/7 activity, which resulted in increased cellular survival in iohexol-treated HK-2 cells. Pretreatment with GKT137831 replicated these effects by decreasing levels of phospho-p38. In a CIAKI mouse model, even though the improvement of plasma blood urea nitrogen was unclear, pretreatment with GKT137831 resulted in preserved structure, reduced expression of 8-hydroxy-2'-deoxyguanosine (8OHdG) and kidney injury molecule-1 (KIM-1), and reduced number of TUNEL (terminal deoxynucleotidyl transferase dUTP nick end labeling)-positive cells. These results suggest Nox4 as a key source of reactive oxygen species responsible for CIAKI and provide a novel potential option for prevention of CIAKI.

MicroRNA‑146a/NAPDH oxidase4 decreases reactive oxygen species generation and inflammation in a diabetic nephropathy model

The present study investigated the role of microRNA (miR)‑146a in a diabetic nephropathy (DN) model, and its molecular mechanism. DN mice were given intraperitoneal injections of streptozotocin (55 mg/kg/day) for 5 consecutive days as an in vivo DN model. The HK‑2 human kidney cell line were exposed to 45% D‑glucose as an in vitro DN model. Firstly, it was demonstrated that miR‑146a expression was inhibited and NAPDH oxidase 4 (Nox4) was increased in DN mice. In HK‑2 cells, overexpression of miR‑146a inhibited Nox4 protein expression and decreased reactive oxygen species (ROS) generation, oxidative stress and inflammation, and suppressed vascular cell adhesion molecule‑1 (VCAM‑1) and intracellular adhesion molecule‑1 (ICAM‑1) protein expression. Nacetylcysteine, a Nox4 inhibitor, was demonstrated to inhibit ROS generation, suppress VCAM‑1 and ICAM‑1 protein expression, and decrease oxidative stress and inflammation in HK‑2 cells following overexpression of miR‑146a. In conclusion, these results indicated that miR‑146a/Nox4 decreases ROS generation and inflammation and prevents DN. Therefore, miR‑146a may represent a novel anti‑inflammatory and ‑oxidative modulator of DN.

Early Growth Response 1 (Egr1) Is a Transcriptional Activator of NOX4 in Oxidative Stress of Diabetic Kidney Disease

BACKGROUND

NADPH oxidase 4 (NOX4) plays a major role in renal oxidative stress of diabetic kidney disease (DKD). NOX4 was significantly increased in Egr1-expressing fibroblasts, but the relationship between Egr1 and NOX4 in DKD is unclear.

METHODS

For the evaluation of the potential relationship between Egr1 and NOX4, both were detected in HFD/STZ-induced mice and HK-2 cells treated with TGF-β1. Then, changes in NOX4 expression were detected in HK-2 cells and mice with overexpression and knockdown of Egr1. The direct relationship between Egr1 and NOX4 was explored via chromatin immunoprecipitation (ChIP).

RESULTS

We found increased levels of Egr1, NOX4, and α-SMA in the kidney cortices of diabetic mice and in TGF-β1-treated HK-2 cells. Overexpression or silencing of Egr1 in HK-2 cells could upregulate or downregulate NOX4 and α-SMA. ChIP assays revealed that TGF-β1 induced Egr1 to bind to the NOX4 promoter. Finally, Egr1 overexpression or knockdown in diabetic mice could upregulate or downregulate the expression of NOX4 and ROS, and α-SMA was also changed.

CONCLUSION

Our study provides strong evidence that Egr1 is a transcriptional activator of NOX4 in oxidative stress of DKD. Egr1 contributes to DKD by enhancing EMT, in part by targeting NOX4.

Ochratoxin A induces ER stress and apoptosis in mesangial cells via a NADPH oxidase-derived reactive oxygen species-mediated calpain activation pathway

Ochratoxin A (OTA) contaminated food increases reactive oxygen species (ROS) production in glomerulus and causes glomerulopathy. The molecular mechanisms still remain uncertain. In this study, we used mouse and rat glomerular mesangial cells and delineate the signaling pathway behind the OTA-triggered cell apoptosis. OTA dose-dependently induced expression of ER stress markers including phospho-PERK, phospho-eIF2α, GRP78, GRP94, and CHOP. Apoptosis events including cleavage of caspase-12, caspase-7, and PARP are also observed. OTA activated oxidative stress and increased NADPH oxidase activity. NADPH oxidase inhibitor, apocynin, significantly attenuated OTA-induced cell apoptosis. Moreover, OTA markedly increased the calpain activity which significantly inhibited by apocynin. Transfection of calpain-siRNA effectively inhibited the OTA-increased ER stress-related protein expression. These findings suggest that OTA activated NADPH oxidase and calpain, induced ER stress and ROS production, and caused glomerular mesangial cells apoptosis which leads to glomerulopathy.

Atorvastatin protects against contrast-induced nephropathy via anti-apoptosis by the upregulation of Hsp27 in vivo and in vitro

Contrast-induced nephropathy (CIN) is an iatrogenic acute renal failure occurring following the intravascular injection of iodinated radiographic contrast medium. However, the regulatory mechanisms for CIN remain to be fully elucidated. The present study aimed to investigate whether atorvastatin protects against CIN via anti-apoptotic effects by the upregulation of Hsp27 in vivo and in vitro. To determine whether atorvastatin attenuated CIN, the inflammatory response and apoptosis in vivo and in vitro, a rat model of iopamidol-induced CIN was used, and human embryonic proximal tubule (HK2) cell damage was assessed. The rats were assigned into four groups (n=10 per group), as follows: Control rats; rats+atorvastatin; rats + iopamidol; rats+iopamidol+atorvastatin. In vitro, the HK2 cells were treated with iopamidol in the presence or absence of atorvastatin, heat shock protein (Hsp)27 small interfering (si)RNA or pcDNA3.1-Hsp27. The renal tissues were examined histopathologically and collected for western blot analysis. The results showed that atorvastatin ameliorated the apoptosis and deterioration of renal function (P<0.05). Furthermore, atorvastatin reduced the iopamidol-induced activity of B cell lymphoma-2 (Bcl-2)-associated X protein (Bax)/caspase-3 and increased the expression of Bcl-2 in vivo and in vitro. Notably, following treatment with Hsp27 siRNA or pcDNA3.1-Hsp27, it was found that iopamidol enhanced or weakened the upregulation of Bax/caspase-3 and downregulation of Bcl-2 in the HK2 cells, respectively. The results of the present study suggested that atorvastatin protected against contrast-induced renal tubular cell apoptosis through the upregulation of Hsp27 in vivo and in vitro.

Unraveling the role of ER stress inhibitors in the context of metabolic diseases

ER stress is provoked by the accumulation of unfolded and misfolded proteins in the ER lumen leading to perturbations in ER homeostasis. ER stress activates a signaling cascade called the Unfolded Protein Response (UPR) which triggers a set of transcriptional and translational events that restore ER homeostasis, promoting cell survival and adaptation. If this adaptive response fails, a terminal UPR program commits such cells to apoptosis. Existing preclinical and clinical evidence testify that prolonged ER stress escalates the risk of several metabolic disorders including diabetes, obesity and dyslipidemia. There have been considerable efforts to develop small molecules that are capable of ameliorating ER stress. Few naturally occurring and synthetic molecules have already been demonstrated for their efficacy in abrogating ER stress in both in vitro and in vivo models of metabolic disorders. This review provides a broad overview of the molecular mechanisms of inhibition of ER stress and its association with various metabolic diseases.

SIRT4 overexpression protects against diabetic nephropathy by inhibiting podocyte apoptosis

Diabetic nephropathy is a diabetic complication associated with capillary damage and increased mortality. Sirtuin 4 (SIRT4) plays an important role in mitochondrial function and the pathogenesis of metabolic diseases, including aging kidneys. The aim of the present study was to investigate the association between SIRT4 and diabetic nephropathy in a glucose-induced mouse podocyte model. A CCK-8 assay showed that glucose simulation significantly inhibited podocyte proliferation in a time- and concentration-dependent manner. Reverse transcription-quantitative polymerase chain reaction and western blot analysis showed that the mRNA and protein levels of SIRT4 were notably decreased in a concentration-dependent manner in glucose-simulated podocytes. However, SIRT4 overexpression increased proliferation and suppressed apoptosis, which was accompanied by increases in mitochondrial membrane potential and reduced production of reactive oxygen species (ROS). Notably, SIRT4 overexpression downregulated the expression of apoptosis-related proteins NOX1, Bax and phosphorylated p38 and upregulated the expression of Bcl-2 in glucose-simulated podocytes. In addition, SIRT4 overexpression significantly attenuated the inflammatory response, indicated by reductions in the levels of TNF-α, IL-1β and IL-6. These results demonstrate for the first time that the overexpression of SIRT4 prevents glucose-induced podocyte apoptosis and ROS production and suggest that podocyte apoptosis represents an early pathological mechanism leading to diabetic nephropathy.

Atorvastatin attenuates contrast-induced nephropathy by modulating inflammatory responses through the regulation of JNK/p38/Hsp27 expression

This study aimed to investigate whether atorvastatin reduce the contrast-induced nephropathy inflammatory response and apoptosis of renal tubular epithelial cells and the relationship with MAPK signaling pathway. We utilized the iopamidol-induced contrast-induced nephropathy (CIN) rat model which was induced by a single dose of iopamidol (2.9 g iodine/kg) and a cell model in which human embryonic proximal tubular (HK2) cells were treated with iopamidol. The rats were divided into five groups: (1) control rats (CR); (2) atorvastatin (CA); (3) iopamidol (CM); (4) iopamidol and atorvastatin (20 mg/kg d) (CMA2); (5) iopamidol and atorvastatin (40 mg/kg d) (CMA4). On days 1, 2 and 6 after iopamidol injection, the urea nitrogen and cystatin C increased in CM compared with CR but decreased in CMA compared with CM. Inflammatory parameters and the percentage of apoptotic cells were increased in CM compared with CR and CA, but they were decreased in CMA compared with CM. We also found that atorvastatin ameliorated the renal tubular necrosis, apoptosis, and the deterioration of renal function in a dose dependent manner (P < 0.05). Furthermore, in vivo, both of SP600125 (JNK inhibitor) and SB203580 (p38 inhibitor) could decrease the expression of Bax and caspase-3, but increase Bcl-2 levels in HK2 cells treated with iopamidol. Our study demonstrates that high-dosage atorvastatin treatment attenuates both the inflammatory processes and apoptosis in contrast-induced acute kidney injury, and that the JNK/p38 MAPK pathway participates in the contrast-induced apoptosis of renal tubular cells. Finally, atorvastatin reduces CIN by suppression of apoptosis, which may be through inhibition of JNK/p38 MAPK pathways.

Oleanolic acid and N-acetylcysteine ameliorate diabetic nephropathy through reduction of oxidative stress and endoplasmic reticulum stress in a type 2 diabetic rat model

BACKGROUND

Hyperglycemia-induced endoplasmic reticulum (ER) stress and oxidative stress could be causes of renal fibrosis in diabetes. Oleanolic acid (OA) naturally occurs in fruits and vegetables. It has anti-inflammatory, antihyperlipidemic and antioxidant effects. N-acetylcysteine (NAC) is a precursor of glutathione, which has a strong antioxidant effect in the body. In this study, we investigated the therapeutic effects of OA and NAC in diabetic nephropathy (DN).

METHODS

Otsuka Long-Evans Tokushima Fatty rats were treated with OA (100 mg/kg/day) or NAC (300 mg/kg/day) for 20 weeks by oral gavage.

RESULTS

The OA or NAC administration increased blood insulin secretion and superoxide dismutase levels, and decreased triglycerides and urinary albumin/creatinine levels. In the kidney, the damaged renal structure recovered with OA or NAC administration, through an increase in nephrin and endothelial selective adhesion molecules and a decrease in transforming growth factor-β/p-smad2/3 and ER stress. Reactive oxygen species and ER stress were increased by high glucose and ER stress inducers in cultured mesangial cells, and these levels recovered with OA (5.0 μM) or NAC (2.5 mM) treatment.

CONCLUSION

The findings in this study suggest that OA and NAC have therapeutic effects for DN through an antioxidant effect and ER stress reduction.

Amelioration of altered antioxidant enzyme activity by Satureja khuzistanica essential oil in alloxan-induced diabetic rats

AIM

To examine the possible protective effect of Satureja khuzistanica essential oil (SKE) on antioxidant enzyme activity in alloxan-induced Type 1 diabetic rats.

METHOD

Thirty Sprague-Dawley male rats were divided into three groups randomly; group one as control, group two diabetic, with no treatment, and group three treatment with SKE at 500 ppm in drinking water, respectively. Diabetes was induced in the second and third groups by alloxan injection subcutaneously. After eight weeks, animals were anaesthetized. Blood samples were also collected before killing to measure antioxidant enzymes activity.

RESULTS

SKE significantly increased the serum level of glutathione and the serum activity of glutathione peroxidase, superoxide dismutase, and catalase in the treated group compared with the diabetic untreated group.

CONCLUSION

The findings showed that SKE exerts beneficial effects on the antioxidant enzymes activity in alloxan-induced Type 1 diabetic rats.

Rosuvastatin attenuates contrast-induced nephropathy through modulation of nitric oxide, inflammatory responses, oxidative stress and apoptosis in diabetic male rats

Background

Contrast-induced nephropathy (CIN) is an important cause of acute renal failure. We observe the effect of rosuvastatin on preventing CIN in diabetic rats in current study.

Methods

Diabetic rats were then divided into five groups: 1 diabetic rats (D), 2 diabetic rats + contrast media (DCM), 3 diabetic rats + rosuvastatin (DR), 4 diabetic rats + contrast media + rosuvastatin (DRCM), 5 non-diabetic rat control (NDCM). Contrast-induced nephropathy was induced by intravenous injection a single dose of indomethacin (10 mg/kg), double doses of N-nitro-L-arginine methyl ester (10 mg/kg) and a single dose of high-osmolar contrast medium meglumine amidotrizoate (6 ml/kg). DR and DRCM group rats were treated with rosuvastatin (10 mg/kg/day) by gavage for 5 days. At the end of treatment, the experimental groups were sacrificed, and their renal tissues were investigated histopathologically beside assessments of functional activities, nitric oxide metabolites, and oxidative stress and apoptic markers.

Results

After 6 days, serum creatinine and urine microprotein were increased, and creatinine clearance, kidney nitrite were decreased in DCM rats compared with NDCM, D, DR and DRCM groups. Histopathology scores in group DCM were increased compared with groups NDCM, D and DR, but lower in group DRCM than in group DCM (p < 0.01). Kidney thiobarbituric acid-reacting substances (TBARS), serum malondialdehyde (MDA), and serum protein carbonyl content (PCC) were increased, and serum thiol was decreased in the DCM group compared with groups NDCM, D and DR; however, these results were reversed in group DRCM compared with group DCM. Both expression of IL-6, TNF-α and the percentage of apoptotic cells were increased in group DCM than in groups NDCM, D and DR, but they were decreased in group DRCM than in group DCM. The expression of phospho-p38, cleaved capase-3, and the Bax/Bcl-2 ratio, were increased in group DCM than in groups NDCM, D and DR, but were decreased in group DRCM than in group DCM.

Conclusions

Our study demonstrated that rosuvastatin treatment attenuated both inflammatory processes and apoptosis and inhibited oxidative stress and the p38 MAPK pathway in a diabetic rat model in the setting of CIN.

Enhanced vascular PI3K/Akt-NOX signaling underlies the peripheral NMDAR-mediated pressor response in conscious rats

The molecular mechanisms for peripheral N-methyl-D-aspartate receptor (NMDAR)-mediated vascular oxidative stress and pressor response are not known. We conducted integrative (in vivo) and ex vivo biochemical studies to test the hypothesis that reactive oxygen species (ROS)-dependent calcium influx, triggered by the activation of vascular kinases, underlies the NMDAR-mediated pressor response. Pharmacological inhibition of phosphoinositide 3-kinase (PI3K)/Akt (wortmannin, 15 μg/kg), protein kinase C (chelerythrine: 5 mg/kg, intravenous), Ca²⁺ influx (nifedipine, 0.35 or 0.75 mg/kg), or NADPH oxidase (NOX: apocynin, 5 mg/kg) attenuated the peripheral NMDAR-mediated pressor response in conscious male Sprague-Dawley rats. NMDAR activation enhanced the phosphorylation of Akt, ERK1, JNK and p38 (Western blot), and NOX activity in vascular tissues collected during the pressor response caused by NMDA infusion (180 μg·kg⁻¹·min⁻¹, 30 minutes). Furthermore, ex vivo studies showed that wortmannin, chelerythrine, or apocynin abrogated the NMDAR-mediated vascular nitric oxide (NO) and ROS generation and NOX activation in the vasculature. These findings implicate vascular PI3K/Akt-protein kinase C signaling in the peripheral NMDAR-mediated increases in vascular NO and NOX activation (ROS), which ultimately lead to calcium influx and pressor response in conscious rats.

Preventive effect of pentoxifylline on contrast-induced acute kidney injury in hypercholesterolemic rats

Oxidative stress is an important mechanism of contrast-induced acute kidney injury (CIAKI). The optimal strategy to prevent CIAKI remains unclear. The aim of the present study was to assess the effect of pentoxifylline, a nonspecific phosphodiesterase inhibitor, on the prevention of CIAKI. A total of 32 healthy male Sprague-Dawley rats were randomly divided into normal dietary group (NN; n=8) and a high cholesterol-supplemented dietary group (HN; 4% cholesterol and 1% cholic acid; n=24). At the end of eight weeks, the rats in the high cholesterol diet group were randomly divided into three subgroups (n=8 in each group). CIAKI was induced in two of the subgroups via intravenous injection of the radiocontrast media iohexol (10 ml/kg). Pentoxifylline (50 mg/kg) was administered to one of the iohexol-treated groups via intraperitoneal injection 12 h prior to and following contrast media (CM) injection. Kidney function parameters and oxidative stress markers were then measured. The renal pathological changes were evaluated using hematoxylin and eosin staining and scored semi-quantitatively. In iohexol-injected rats, serum creatinine (Scr), renal pathological scores, renal malondialdehyde (MDA) content, renal NADPH oxidase activity, fractional excretion of sodium (FENa%) and fractional excretion of potassium (FEK%) were significantly increased (P<0.01). The Scr, histologic scores, renal MDA content, NADPH oxidase activity, FENa% and FEK% in the rats treated with pentoxifylline prior to iohexol were observed to be reduced compared with those in rats treated with iohexol alone (P<0.01). This suggests that pentoxifylline significantly attenuates renal injuries, including tubular necrosis and proteinaceous casts induced by CM. It may be concluded that pentoxifylline protected the renal tissue from the nephrotoxicity induced by low-osmolar CM via an antioxidant effect.

Amelioration of lipid peroxidation in vivo and in vitro by Satureja khozestanica essential oil in alloxan-induced diabetic rats

Background

We examined possible protective effect of Satureja khozestanica essential oil (SKE) on in vivo and in vitro lipid peroxidation in alloxan-induced Type 1 diabetic rats.

Methods

Thirty Sprage-dawley male rats were divided into three groups randomly; group one as control, group two diabetic untreatment, and group three treatments with SKE by 500 ppm in drinking water, respectively. Diabetes was induced in the second and third groups by alloxan injection subcutaneously. After 8 weeks, animals were anaesthetized, livers and kidneys were then removed immediately and used fresh or kept frozen until their lipid peroxidation analysis. Lipid peroxidation was determined by measurement of thiobarbituric acid reactive substances (TBARS). Blood samples were also collected before killing to measure the levels of fasting blood suger (FBS) and lipid peroxidation.

Results

SKE significantly inhibited the levels of FBS, TBARS serum and kidney content in treated group compared with the diabetic untreated group. Also the levels of malonedialdehyde liver content unaltered in treated group. SKE significantly inhibited LDL oxidation in vitro.

Conclusions

The findings showed that SKE exerts beneficial effects on the lipid peroxidation in alloxan-induced Type 1 diabetic rats.

Wld(S) ameliorates renal injury in a type 1 diabetic mouse model

Diabetic nephropathy (DN) is the leading cause of end-stage kidney disease worldwide. The purpose of this study is to investigate whether the Wld(S) (slow Wallerian degeneration; also known as Wld) gene plays a renoprotective role during the progression of DN. Diabetes was induced in 8-wk-old male wild-type (WT) and C57BL/Wld(S) mice by streptozotocin (STZ) injection. Blood and urinary variables including blood glucose, glycated hemoglobin (GHb), insulin, urea nitrogen, and albumin/creatinine ratio were assessed 4, 7, and 14 wk after STZ injection. Periodic acid-Schiff staining, Masson staining, and silver staining were performed for renal pathological analyses. In addition, the renal ultrastructure was observed by electron microscope. The activities of p38 and ERK signaling in renal cortical tissues were evaluated by Western blotting. NAD(+)/NADH ratio and NADPH oxidase activity were also measured. Moreover, the expressions of TNF-α, IL-1, and IL-6 were examined. We provide experimental evidence demonstrating that the Wld(S) gene is expressed in kidney cells and protects against the early stage of diabetes-induced renal dysfunction and extracellular matrix accumulation through delaying the reduction of the NAD(+)/NADH ratio, inhibiting the activation of p38 and ERK signaling, and suppressing oxidative stress as evidenced by the decreased NADPH oxidase activity and lower expression of TNF-α, IL-1, and IL-6.

Parthenolide generates reactive oxygen species and autophagy in MDA-MB231 cells. A soluble parthenolide analogue inhibits tumour growth and metastasis in a xenograft model of breast cancer

Triple-negative breast cancers (TNBCs) are clinically aggressive forms associated with a poor prognosis. We evaluated the cytotoxic effect exerted on triple-negative MDA-MB231 breast cancer cells both by parthenolide and its soluble analogue dimethylamino parthenolide (DMAPT) and explored the underlying molecular mechanism. The drugs induced a dose- and time-dependent decrement in cell viability, which was not prevented by the caspase inhibitor z-VAD-fmk. In particular in the first hours of treatment (1–3 h), parthenolide and DMAPT strongly stimulated reactive oxygen species (ROS) generation. The drugs induced production of superoxide anion by activating NADPH oxidase. ROS generation caused depletion of thiol groups and glutathione, activation of c-Jun N-terminal kinase (JNK) and downregulation of nuclear factor kB (NF-kB). During this first phase, parthenolide and DMAPT also stimulated autophagic process, as suggested by the enhanced expression of beclin-1, the conversion of microtubule-associated protein light chain 3-I (LC3-I) to LC3-II and the increase in the number of cells positive to monodansylcadaverine. Finally, the drugs increased RIP-1 expression. This effect was accompanied by a decrement of pro-caspase 8, while its cleaved form was not detected and the expression of c-FLIP_S markedly increased. Prolonging the treatment (5–20 h) ROS generation favoured dissipation of mitochondrial membrane potential and the appearance of necrotic events, as suggested by the increased number of cells positive to propidium iodide staining. The administration of DMAPT in nude mice bearing xenografts of MDA-MB231 cells resulted in a significant inhibition of tumour growth, an increment of animal survival and a marked reduction of the lung area invaded by metastasis. Immunohistochemistry data revealed that treatment with DMAPT reduced the levels of NF-kB, metalloproteinase-2 and -9 and vascular endothelial growth factor, while induced upregulation of phosphorylated JNK. Taken together, our data suggest a possible use of parthenolide for the treatment of TNBCs.

The signaling pathway of NADPH oxidase and its role in glomerular diseases

Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (Nox), a major source of reactive oxygen species, is a critical mediator of redox signaling. It is well-documented that oxidative stress is associated with the development of glomerular diseases (GN). Hence, the Nox was also thought to be involved in the pathogenesis of GN. However, the expression of Nox in various GN was not consistent, the mechanisms by which the activity of the Nox enzymes in regulating renal cells remains unclear. Signaling pathways might be very important in the pathogenesis of GN. We performed this review to provide a relatively complete signaling pathways flowchart for Nox to the investigators who were interested in the role of Nox in the pathogenesis of GN. Here, we reviewed the signal transduction pathway of Nox and its role in the pathogenesis of GN.

Radiographic contrast-media-induced acute kidney injury: pathophysiology and prophylactic strategies

Contrast-induced acute kidney injury (CI-AKI) is one of the most widely discussed and debated topics in cardiovascular medicine. With increasing number of contrast-media- (CM-) enhanced imaging studies being performed and growing octogenarian population with significant comorbidities, incidence of CI-AKI remains high. In this review, pathophysiology of CI-AKI, its relationship with different types of CM, role of serum and urinary biomarkers for diagnosing CI-AKI, and various prophylactic strategies used for nephroprotection against CI-AKI are discussed in detail.

Aged rats are susceptible to nephrotoxicity induced by iodinated contrast media

OBJECTIVE

The objective of this study is to evaluate the effect and mechanism of aging on iodinated-contrast-media-induced nephropathy in male rats.

METHODS

Twenty-four healthy male rats were initially divided into 12-month-old and 24-month-old age groups (adult and older age groups, respectively; n = 12/group); subsequently, each age group was randomly divided into saline control (NS) and contrast media (CM) groups (n = 6/group). CM (76% diatrizoate, 10 mL/kg b.w.) was given through the caudal vein. Urinary creatinine (Ucr) and serum creatinine (Scr) were detected by an automatic biochemical analyzer. The activities of renal malondialdehyde (MDA), superoxide dismutase (SOD), angiotensin-converting enzyme (ACE), angiotensin II (Ang II), and reduced form of nicotinamide adenine dinucleotide phosphate oxidase (NADPH oxidase) were determined by spectrophotometric assays with commercially available kits according to the manufacturers' protocols. Renal histological changes were observed by hematoxylin and eosin staining and scored semiquantitatively.

RESULTS

In diatrizoate-injected aged rats, Scr, the activities of ACE, Ang II, MDA, and NADPH oxidase in renal tissues were significantly increased (p < 0.01). The histologic scores were higher in the aged animals with CM treatment than those of control or adult rats (p < 0.01). There was an increasing trend but no significant statistical difference in renal ACE, Ang II, MDA, and NADPH oxidase or histologic scores in adult CM-injected rats compared with control animals (p > 0.05).

CONCLUSIONS

Older age is an aggravating factor of iodinated-contrast-media-induced nephropathy in male rats. Oxidative stress and the renin-angiotensin system (RAS) may play an important role in nephrotoxicity induced by iodinated contrast media, especially in aged male rats.

Amelioration of altered antioxidant enzymes activity and glomerulosclerosis by coenzyme Q10 in alloxan-induced diabetic rats

Coenzyme Q10 is a natural antioxidant and scavenging free radicals. In the present study, we examined antioxidative activities of coenzyme Q10 and possible protective effect of coenzyme Q10 on in vivo and in vitro lipid peroxidation, antioxidant enzymes activity and glomerulosclerosis in alloxan-induced type 1 diabetic rats. Thirty Sprague-Dawley male rats were divided into three groups randomly: group 1 as control, group 2 as diabetic untreatment, and group 3 as treatments with coenzyme Q10 by 15 mg/kg i.p. daily, respectively. Diabetes was induced in the second and third groups by alloxan injection subcutaneously. After 8 weeks, animals were anaesthetized, liver and kidney were then removed immediately and used fresh or kept frozen until their lipid peroxidation analysis. Blood samples were also collected before killing to measure the lipid peroxidation and antioxidant enzymes activity. Kidney paraffin sections were prepared and stained by periodic acid-Schiff method. Glomerular volume and leukocyte infiltration were estimated by stereological rules and glomerular sclerosis was studied semi-quantitatively. Coenzyme Q10 significantly inhibited leukocyte infiltration, glomerulosclerosis and the levels of malondialdehyde (MDA) serum and kidney content in treated group compared with the diabetic untreated group. Coenzyme Q10 significantly inhibited LDL oxidation in vitro. Coenzyme Q10 significantly increased the serum levels of glutathione (GSH) and serum activity of catalase (CAT) and superoxide dismutase (SOD) in treated group compared with the diabetic untreated group. Coenzyme Q10 alleviates leukocyte infiltration and glomerulosclerosis and exerts beneficial effects on the lipid peroxidation and antioxidant enzymes activity in alloxan-induced type 1 diabetic rats.