Anti-Inflammatory Therapy Modulates Nrf2-Keap1 in Kidney from Rats with Diabetes

Research progress on the role and inhibitors of Keap1 signaling pathway in inflammation

Inflammation is a protective mechanism against endogenous and exogenous pathogens. It is a typical feature of numerous chronic diseases and their complications. Keap1 is an essential target in oxidative stress and inflammatory diseases. Among them, the Keap1-Nrf2-ARE pathway (including Keap1-Nrf2-HO-1) is the most significant pathway of Keap1 targets, which participates in the control of inflammation in multiple organs (including renal inflammation, lung inflammation, liver inflammation, neuroinflammation, etc.). Identifying new Keap1 inhibitors is crucial for new drug discovery. However, most drugs have specificity issues as they covalently bind to cysteine residues of Keap1, causing off-target effects. Therefore, direct inhibition of Keap1-Nrf2 PPIs is a new research idea. Through non-electrophilic and non-covalent binding, its inhibitors have better specificity and ability to activate Nrf2, and targeting therapy against Keap1-Nrf2 PPIs has become a new method for drug development in chronic diseases. This review summarizes the members and downstream genes of the Keap1-related pathway and their roles in inflammatory disease models. In addition, we summarize all the research progress of anti-inflammatory drugs targeting Keap1 from 2010 to 2024, mainly describing their biological functions, molecular mechanisms of action, and therapeutic roles in inflammatory diseases.

Exploring the NRF2/HO-1 and NF-κB Pathways: Spirulina Nanoparticles as a Novel Approach to Combat Diabetic Nephropathy

Arthrospira platensis has been the subject of plentiful studies due to its purported health advantages; nevertheless, additional investigation is required to determine whether several chronic diseases may be treated or avoided with its nanoform. Therefore, we set out to examine A. platensis nanoparticles (SNPs) to protect against kidney impairment caused by Streptozotocin (STZ) in diabetic rats, precisely focusing on its effect and the cellular intracellular pathways involved. Male Wistar rats were assigned into four groups: Group 1 was set as control, comprising the normal rats; group 2 was administered SNPs (0.5 mg/kg BW, once/day) orally for 84 consecutive days; group 3, STZ-diabetic rats were injected with STZ (65 mg/kg BW); and group 4, in which the diabetic rats were treated with SNPs. After inducing diabetes in rats for 84 days, the animals were euthanized. The results disclosed that SNP treatment substantially (P < 0.05) improved the glucose and glycated hemoglobin levels (HbA1c %), insulin, C-peptide, and cystatin C deterioration in diabetic rats. Furthermore, SNP administration significantly lowered (P < 0.05) nitric oxide (NO) and malondialdehyde (MDA) levels in renal tissue and enhanced kidney function metrics, as well as improved the antioxidant capacity of the renal tissue. In addition, oral SNPs overcame the diabetic complications concerning diabetic nephropathy, indicated by downregulation and upregulation of apoptotic and antiapoptotic genes, respectively, along with prominent modulation of the antiangiogenic marker countenance level, improving kidney function. SNP modulated the nuclear factor erythroid 2-related factor 2 and heme oxygenase-1 (NRF2/HO-1) pathways and inhibited the nuclear factor-κB (NF-κB) expression, strengthening the SNP pathways in alleviating diabetic nephropathy. The histopathology results corroborated the obtained biochemical and molecular observations, suggesting the therapeutic potential of SNPs in diabetic nephropathy via mechanisms other than its significant antioxidant and hypoglycemic effects, including modulation of antiangiogenic and inflammatory mediators and the NRF2/HO-1 pathways.

Glucose transport, transporters and metabolism in diabetic retinopathy

Diabetic retinopathy (DR) is the most common reason for blindness in working-age individuals globally. Prolonged high blood glucose is a main causative factor for DR development, and glucose transport is prerequisite for the disturbances in DR caused by hyperglycemia. Glucose transport is mediated by its transporters, including the facilitated transporters (glucose transporter, GLUTs), the "active" glucose transporters (sodium-dependent glucose transporters, SGLTs), and the SLC50 family of uniporters (sugars will eventually be exported transporters, SWEETs). Glucose transport across the blood-retinal barrier (BRB) is crucial for nourishing the neuronal retina in the context of retinal physiology. This physiological process primarily relies on GLUTs and SGLTs, which mediate the glucose transportation across both the cell membrane of retinal capillary endothelial cells and the retinal pigment epithelium (RPE). Under diabetic conditions, increased accumulation of extracellular glucose enhances the retinal cellular glucose uptake and metabolism via both glycolysis and glycolytic side branches, which activates several biochemical pathways, including the protein kinase C (PKC), advanced glycation end-products (AGEs), polyol pathway and hexosamine biosynthetic pathway (HBP). These activated biochemical pathways further increase the production of reactive oxygen species (ROS), leading to oxidative stress and activation of Poly (ADP-ribose) polymerase (PARP). The activated PARP further affects all the cellular components in the retina, and finally resulting in microangiopathy, neurodegeneration and low-to-moderate grade inflammation in DR. This review aims to discuss the changes of glucose transport, glucose transporters, as well as its metabolism in DR, which influences the retinal neurovascular unit (NVU) and implies the possible therapeutic strategies for treating DR.

Crataeva nurvala Bark (Capparidaceae) Extract Modulates Oxidative Stress-Related Gene Expression, Restores Antioxidant Enzymes, and Prevents Oxidative Stress in the Kidney and Heart of 2K1C Rats

Objective

Crataeva nurvala is a medicinal plant, which contains a wide range of polyphenolic and bioactive compounds. The aim of the study was to evaluate the renal-protective activity of Crataeva nurvala in two-kidney, one-clip (2K1C) rats.

Methods

In this study, the ethanol extract of Crataeva nurvala bark at a dose of 100 mg/kg was orally used to treat 2K1C rats for four weeks. At the end of the experiment, all rats were sacrificed and tissue samples were collected for further biochemical and histological assessments.

Results

This investigation showed that Crataeva nurvala treatment prevented the kidney dysfunction in 2K1C rats. Uric acid and creatinine concentration and CK-MB activities increased in 2K1C rats which were normalized by Crataeva nurvala. 2K1C rats also showed increased oxidative stress, depicted by the elevated level of MDA, NO, and APOP in plasma and tissues. Oxidative stress parameters declined in 2K1C rats by the treatment of Crataeva nurvala. These results could be attributed to the restoration of antioxidant enzyme activities such as catalase and SOD. Crataeva nurvala extracts also upregulated antioxidant gene expression in the kidneys of 2K1C rats. Moreover, several anti-inflammatory genes were suppressed by Crataeva nurvala treatment in 2K1C rats. Furthermore, fibrosis and collagen deposition in the kidneys were also lowered by the treatment of the Crataeva nurvala extract.

Conclusion

The experimental data suggest that the Crataeva nurvala extract protected renal damage and oxidative stress, probably by restoring antioxidant enzymes activities in 2K1C rats.

Beneficial effects of ginsenosides on diabetic nephropathy: A systematical review and meta-analysis of preclinical evidence

ETHNOPHARMACOLOGICAL RELEVANCE

Ginseng is one of the most widely used herbs in the world for the treatment of various diseases, and ginsenoside is the representative bioactive component in ginseng. There have been many in vivo studies on ginsenoside for the treatment of diabetic nephropathy (DN), the most common diabetic microvascular complication and the main cause of diabetic morbidity and mortality.

AIM OF THE STUDY

The purpose of this study is to evaluate the efficacy of ginsenosides on DN by preclinical evidence and meta-analysis. Meanwhile, the main possible action mechanisms of ginsenosides against DN were also summarized.

MATERIALS AND METHODS

We systematically searched PubMed, WOS, Embase, Cochrane, WanFang, Cqvip, CNKI and CBM databases from January 1, 2000, to November 15, 2021, to evaluate the animal experiments of ginsenosides for the treatment of DN. Finally, 30 animal experiments were included. Twelve outcome measures, including renal function indicators (24-h urine protein, serum creatinine, urea nitrogen, creatinine clearance, uric acid, urinary albumin to creatinine ratio), oxidative stress biomarkers (GPX, MDA, SOD), inflammatory factors (IL-1, IL-6, TNF-α) were obtained by using RevMan 5.4 software for meta-analysis.

RESULTS

The results showed that except for no significant difference in CCr, other indicators such as 24h UP, SCr, blood urea nitrogen, uric acid and UACR were significantly decreased. It showed that ginsenoside could improve renal function in diabetes. Meanwhile ginsenoside significantly up-regulated antioxidant enzymes SOD and GPX, down-regulated MDA and inflammatory factors IL-1, IL-6 and TNF-α, indicating that ginsenoside may have antioxidant and anti-inflammatory effects.

CONCLUSION

Ginsenoside can protect against the renal failure in diabetes through anti-inflammation, anti-oxidation, anti-renal fibrosis, anti-apoptosis/pyroptosis, regulation of blood glucose/lipid metabolism, etc. Which provides preclinical evidence for the application of ginsenoside in the treatment of DN.

Oxidative Stress and NRF2/KEAP1/ARE Pathway in Diabetic Kidney Disease (DKD): New Perspectives

Diabetes mellitus (DM) is one of the most debilitating chronic diseases worldwide, with increased prevalence and incidence. In addition to its macrovascular damage, through its microvascular complications, such as Diabetic Kidney Disease (DKD), DM further compounds the quality of life of these patients. Considering DKD is the main cause of end-stage renal disease (ESRD) in developed countries, extensive research is currently investigating the matrix of DKD pathophysiology. Hyperglycemia, inflammation and oxidative stress (OS) are the main mechanisms behind this disease. By generating pro-inflammatory factors (e.g., IL-1,6,18, TNF-α, TGF-β, NF-κB, MCP-1, VCAM-1, ICAM-1) and the activation of diverse pathways (e.g., PKC, ROCK, AGE/RAGE, JAK-STAT), they promote a pro-oxidant state with impairment of the antioxidant system (NRF2/KEAP1/ARE pathway) and, finally, alterations in the renal filtration unit. Hitherto, a wide spectrum of pre-clinical and clinical studies shows the beneficial use of NRF2-inducing strategies, such as NRF2 activators (e.g., Bardoxolone methyl, Curcumin, Sulforaphane and their analogues), and other natural compounds with antioxidant properties in DKD treatment. However, limitations regarding the lack of larger clinical trials, solubility or delivery hamper their implementation for clinical use. Therefore, in this review, we will discuss DKD mechanisms, especially oxidative stress (OS) and NRF2/KEAP1/ARE involvement, while highlighting the potential of therapeutic approaches that target DKD via OS.

Heparanase promotes endothelial-to-mesenchymal transition in diabetic glomerular endothelial cells through mediating ERK signaling

Glomerular endothelial cells (GEnCs) dysfunction occurs at the early stage of diabetic nephropathy (DN). One of its characteristics is endothelial-to-mesenchymal transition (EndMT). Heparanase (HPSE) is the only known mammalian endoglycosidase capable of degrading heparin sulfates and has a prominent role in DN pathogenesis. However, whether HPSE induces EndMT of GEnCs remains unknown. This study aimed to determine the effect and potential mechanism of HPSE on GEnCs phenotype under high-glucose conditions. In the early development of streptozotocin (STZ)-induced diabetic mice, HPSE overexpression was positively correlated with renal injury and the number of GEnCs undergoing EndMT, which was characterized by loss of endothelial marker CD31 and gain of mesenchymal markers including α-SMA and Snail1/2 by double immunofluorescence staining. Bioinformatics analysis revealed a positive correlation between HPSE and ERK. The counts of double positive staining of CD31 and p-ERK1/2 was significantly increased in the glomeruli of STZ-induced diabetic mice compared with sham mice. In cultured GEnCs, high glucose dramatically upregulated the expressions of HPSE and p-ERK1/2, both of which were markedly blocked by HPSE siRNA. Furthermore, recombinant mouse HPSE (rmHPSE) promoted the expressions of mesenchymal markers and p-ERK1/2 in a dosage- and time-dependent manner. U0126, a specific MEK/ERK inhibitor, significantly inhibited either high glucose or rmHPSE-induced EndMT of GEnCs. These data indicate that high glucose induces EndMT of GEnCs at least partially through upregulating HPSE and that HPSE promotes EndMT of GEnCs via activating ERK signaling. This study improves understanding the crucial role of HPSE in DN development and progression.

Bisacurone attenuates diabetic nephropathy by ameliorating oxidative stress, inflammation and apoptosis in rats

BACKGROUND

Diabetes nephropathy (DN) is a serious diabetic problem that may progress to renal failure. The root of Curcuma longa L., often known as turmeric, provides various health benefits. Bisacurone is a bioactive terpenoid found in small amounts in turmeric that possesses anti-inflammatory and antioxidant properties. The present study focuses on the potential protective effects of bisacurone against DN via reducing renal inflammation, oxidative stress, and apoptosis.

METHODS

Type 2 diabetes was created in rats by feeding them a high-fat/high-sugar diet for 8 weeks, followed by a low dose of streptozotocin and Bisacurone (50 and 100 μg/kg bisacurone) given for 4 weeks.

RESULTS

In diabetic rats, bisacurone reduced hyperglycemia, protected against body weight (BW) loss, lowered renal markers, reduced lipid profile alterations and avoided histological abnormalities. Bisacurone treatment reduced oxidative stress by decreasing malondialdehyde (MDA) levels while enhancing antioxidant defenses through superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) levels. Furthermore, bisacurone treatment activated the renal Nrf2/Keap1 signaling pathway but attenuated the high levels of NFκB p65, TNF-α, IL-1β, IL-6, Cox2, and iNOS. Bisacurone also reduced Bax, caspase-3, caspase-9 and cytochrome c but increased Bcl-2 in the kidneys of diabetic rats.

CONCLUSION

In the present study, bisacurone reduces DN by reducing hyperglycemia, oxidative stress, inflammation, and apoptosis, while also increasing Nrf2/HO-1 signaling.

Chronic Inflammation in Chronic Kidney Disease Progression: Role of Nrf2

Despite recent advances in the management of chronic kidney disease (CKD), morbidity and mortality rates in these patients remain high. Although pressure-mediated injury is a well-recognized mechanism of disease progression in CKD, emerging data indicate that an intermediate phenotype involving chronic inflammation, oxidative stress, hypoxia, senescence, and mitochondrial dysfunction plays a key role in the etiology, progression, and pathophysiology of CKD. A variety of factors promote chronic inflammation in CKD, including oxidative stress and the adoption of a proinflammatory phenotype by resident kidney cells. Regulation of proinflammatory and anti-inflammatory factors through NF-κB- and nuclear factor, erythroid 2 like 2 (Nrf2)-mediated gene transcription, respectively, plays a critical role in the glomerular and tubular cell response to kidney injury. Chronic inflammation contributes to the decline in glomerular filtration rate (GFR) in CKD. Whereas the role of chronic inflammation in diabetic kidney disease (DKD) has been well-elucidated, there is now substantial evidence indicating unresolved inflammatory processes lead to fibrosis and eventual end-stage kidney disease (ESKD) in several other diseases, such as Alport syndrome, autosomal-dominant polycystic kidney disease (ADPKD), IgA nephropathy (IgAN), and focal segmental glomerulosclerosis (FSGS). In this review, we aim to clarify the mechanisms of chronic inflammation in the pathophysiology and disease progression across the spectrum of kidney diseases, with a focus on Nrf2.

Icariin ameliorates streptozocin-induced diabetic nephropathy through suppressing the TLR4/NF-κB signal pathway

Diabetic nephropathy (DN) is one of the complex and severe complications of diabetes mellitus (DM). Icariin (ICA) is a flavonoid extracted from the leaves and stems of Herba epimedii with a wide range of pharmacological effects, such as anti-osteoporosis, anti-fibrosis, anti-aging, anti-inflammation and antioxidation. The purpose of our study was to explore the renal protective effect of ICA on DN in mice and its possible mechanisms. ICR mice were exposed to STZ-induced DN. The kidney organ coefficient of mice was computed. 24 h UP in urine was measured. Serum FBG, Cr and BUN were detected. The content of MDA and the activities of SOD, CAT and GSH-Px in renal tissues were tested. HE staining, PAS staining, PASM staining and transmission electron microscopy were used to observe renal pathological changes. Furthermore, TLR4, p-NF-κB p65, TNF-α and IL-6 of renal tissues were assayed by immunohistochemistry and western blotting. Our results indicated that ICA observably optimized the renal organ coefficient, reduced the level of 24 h UP in urine, decreased the content of Cr, BUN in serum and MDA in renal tissues, promoted the activities of SOD, CAT and GSH-Px in renal tissues, and ameliorated pathological lesions of kidneys noticeably. Besides, ICA inhibited the expressions of TLR4, p-NF-κB p65, TNF-α and IL-6 remarkably in renal tissues. ICA, which might lighten the renal inflammatory response by suppressing the TLR4/NF-κB signal pathway, played a protective role in kidneys of STZ-induced DN mice.

The Laetiporus sulphureus Fermented Product Enhances the Antioxidant Status, Intestinal Tight Junction, and Morphology of Broiler Chickens

Simple Summary

This study investigated the effects of the Laetiporus sulphureus fermented product (FL) as a feed supplement on antioxidant activities, intestinal Tight Junction (TJ) mRNA expression, and the intestinal morphology of broiler chickens. FL supplementation could potentially enhance the feed conversion ratio in broilers by improving their antioxidative status, TJ mRNA expression, and intestinal morphology. Broilers supplemented with 5% FL exhibited the best overall results on improving antioxidant status, TJ mRNA expression, and intestinal morphology.

Abstract

The Laetiporus sp. is a fungal species that is traditionally used for medicinal purposes. This study investigated the effects of the Laetiporus sulphureus fermented product (FL) as a feed supplementation on the antioxidant activities, the intestinal Tight Junction (TJ) mRNA expression, and the intestinal morphology of broiler chickens. Four-hundred one-day-old male broilers (Ross 308) were randomly allocated to five experimental diets: (1) a corn-soybean meal basal diet (control), (2) a basal diet replaced with 5% Wheat Bran (5% WB), (3) a basal diet replaced with 10% WB (10% WB), (4) a basal diet replaced with 5% FL (5% FL), and (5) a basal diet replaced with 10% FL (10% FL). The FL-supplemented groups exhibited a better feed conversion ratio in the overall experimental period compared to the WB and control groups. The serum antioxidant profiles of 35-day-old broilers showed that, compared to the control and 10% WB groups, the 5% FL supplementation group had a significantly increased superoxide dismutase activity, while it down-regulated the concentration of malondialdehyde in the serum (p < 0.05). The assessment of selected antioxidant gene expression showed that the 5% FL group significantly elevated heme oxygenase-1 and nuclear factor erythroid 2–related factor 2 expression, compared to the control and WB groups (p < 0.05). Furthermore, both of the FL supplemented groups had a significantly higher expression of glutathione peroxidase and catalase, compared to that of the WB and control groups in the jejunum (p < 0.05). The TJ mRNA expression in the jejunum showed that 5% FL significantly elevated the zonula occludens-1, claudin-1, and mucin-2 expression (p < 0.05), while 5% and 10% FL supplementation significantly improved OCLN expression in both the jejunum and ileum, compared to control group (p < 0.05). The intestinal morphology of 35-day-old broilers showed that a 5% FL supplementation significantly increased the villus height in the ileum and jejunum, compared to the WB and control groups (p < 0.05). Moreover, the 5% and 10% FL supplementation groups had a significantly higher villi:crypt ratio in the ileum, compared to the WB and control groups (p < 0.05). To conclude, FL supplementation improved the antioxidative status, the TJ mRNA expression, and the intestinal morphology, and it was accompanied by a lowered feed conversion ratio in broilers. Finally, 5% supplementation had the overall best results in improving the antioxidant status, TJ mRNA expression, and intestinal morphology of broilers.

Unfolding Nrf2 in diabetes mellitus

In spite of much awareness, diabetes mellitus continues to remain one of major reasons for mortality and morbidity rate all over the globe. Free radicals cause oxidative stress which is responsible for causing diabetes. The recent advancements in elucidation of ARE/keap1/Nrf2 pathway can help in better understanding of diabetes mellitus. Various clinical trials and animal studies have shown the promising effect of Nrf2 pathway in reversing diabetes by counteracting with the oxidative stress produced. The gene is known to dissociate from Keap1 on coming in contact with such stresses to show preventive and prognosis effect. The Nrf2 gene has been marked as a molecular player in dealing with wide intracellular as well as extracellular cellular interactions in different diseases. The regulation of this gene gives some transcription factor that contain antioxidant response elements (ARE) in their promoter region and thus are responsible for encoding certain proteins involved in regulation of metabolic and detoxifying enzymes.

An Overview of Nrf2 Signaling Pathway and Its Role in Inflammation

Inflammation is a key driver in many pathological conditions such as allergy, cancer, Alzheimer’s disease, and many others, and the current state of available drugs prompted researchers to explore new therapeutic targets. In this context, accumulating evidence indicates that the transcription factor Nrf2 plays a pivotal role controlling the expression of antioxidant genes that ultimately exert anti-inflammatory functions. Nrf2 and its principal negative regulator, the E3 ligase adaptor Kelch-like ECH- associated protein 1 (Keap1), play a central role in the maintenance of intracellular redox homeostasis and regulation of inflammation. Interestingly, Nrf2 is proved to contribute to the regulation of the heme oxygenase-1 (HO-1) axis, which is a potent anti-inflammatory target. Recent studies showed a connection between the Nrf2/antioxidant response element (ARE) system and the expression of inflammatory mediators, NF-κB pathway and macrophage metabolism. This suggests a new strategy for designing chemical agents as modulators of Nrf2 dependent pathways to target the immune response. Therefore, the present review will examine the relationship between Nrf2 signaling and the inflammation as well as possible approaches for the therapeutic modulation of this pathway.

CdSe/ZnS quantum dots exhibited nephrotoxicity through mediating oxidative damage and inflammatory response

Objective: This study aimed to the evaluate the nephrotoxicity of CdSe/ZnS QDs in vitro and vivo, as well as investigate the underlying toxicity mechanisms.

Results: In vitro experiments showed that compared with control cells, CdSe/ZnS QDs treatment significantly inhibited cell viability and promoted cell apoptosis in dose-dependent manner in NRK cells. Notably, CdSe/ZnS QDs treatment increased the contents of MDA and ROS, and decreased the activities of SOD, CAT and GSH-Px; however, the co-treatment of NAC and QDs relieved the oxidative damage of NRK cells. Moreover, in vivo experiments also revealed that CdSe/ZnS QDs treatment obviously increased kidney weight coefficient, damaged the kidney function, as well as induced inflammatory response and inhibited the activation of NRF2/Keap1 pathway in kidney tissues of mice.

Conclusions: CdSe/ZnS QDs exhibited obvious nephrotoxicity by mediating oxidative damage and inflammatory response in vitro and in vivo via NRF2/Keap1 pathway.

Methods: The characterization of CdSe/ZnS QDs was analyzed by transmission electron microscope, emission spectrum scanning, and dynamic light scattering. Rat kidney cells (NRK) were exposed to different doses of CdSe/ZnS QDs with or without N-acetylcysteine (NAC, antioxidant). Then, cellular uptake of CdSe/ZnS QDs was detected, and in vitro cytotoxicity was evaluated by MTT assay and TUNEL assay.

Effects of Allicin on Pathophysiological Mechanisms during the Progression of Nephropathy Associated to Diabetes

This study aimed to assess the impact of allicin on the course of diabetic nephropathy. Study groups included control, diabetes, and diabetes-treated rats. Allicin treatment (16 mg/kg day/p.o.) started after 1 month of diabetes onset and was administered for 30 days. In the diabetes group, the systolic blood pressure (SBP) increased, also, the oxidative stress and hypoxia in the kidney cortex were evidenced by alterations in the total antioxidant capacity as well as the expression of nuclear factor (erythroid-derived 2)-like 2/Kelch ECH associating protein 1 (Nrf2/Keap1), hypoxia-inducible factor 1-alpha (HIF-1α), vascular endothelial growth factor (VEGF), erythropoietin (Epo) and its receptor (Epo-R). Moreover, diabetes increased nephrin, and kidney injury molecule-1 (KIM-1) expression that correlated with mesangial matrix, the fibrosis index and with the expression of connective tissue growth factor (CTGF), transforming growth factor-β1 (TGF-β1), and α-smooth muscle actin (α-SMA). The insulin levels and glucose transporter protein type-4 (GLUT4) expression were decreased; otherwise, insulin receptor substrates 1 and 2 (IRS-1 and IRS-2) expression was increased. Allicin increased Nrf2 expression and decreased SBP, Keap1, HIF-1α, and VEGF expression. Concurrently, nephrin, KIM-1, the mesangial matrix, fibrosis index, and the fibrotic proteins were decreased. Additionally, allicin decreased hyperglycemia, improved insulin levels, and prevented changes in (GLUT4) and IRSs expression induced by diabetes. In conclusion, our results demonstrate that allicin has the potential to help in the treatment of diabetic nephropathy. The cellular mechanisms underlying its effects mainly rely on the regulation of antioxidant, antifibrotic, and antidiabetic mechanisms, which can contribute towards delay in the progression of renal disease.

Oxidative stress and diabetic retinopathy: Molecular mechanisms, pathogenetic role and therapeutic implications

Oxidative stress, a cytopathic outcome of excessive generation of ROS and the repression of antioxidant defense system for ROS elimination, is involved in the pathogenesis of multiple diseases, including diabetes and its complications. Retinopathy, a microvascular complication of diabetes, is the primary cause of acquired blindness in diabetic patients. Oxidative stress has been verified as one critical contributor to the pathogenesis of diabetic retinopathy. Oxidative stress can both contribute to and result from the metabolic abnormalities induced by hyperglycemia, mainly including the increased flux of the polyol pathway and hexosamine pathway, the hyper-activation of protein kinase C (PKC) isoforms, and the accumulation of advanced glycation end products (AGEs). Moreover, the repression of the antioxidant defense system by hyperglycemia-mediated epigenetic modification also leads to the imbalance between the scavenging and production of ROS. Excessive accumulation of ROS induces mitochondrial damage, cellular apoptosis, inflammation, lipid peroxidation, and structural and functional alterations in retina. Therefore, it is important to understand and elucidate the oxidative stress-related mechanisms underlying the progress of diabetic retinopathy. In addition, the abnormalities correlated with oxidative stress provide multiple potential therapeutic targets to develop safe and effective treatments for diabetic retinopathy. Here, we also summarized the main antioxidant therapeutic strategies to control this disease.

•

Oxidative stress can both contribute to and result from hyperglycemia-induced metabolic abnormalities in retina.

•

Genes important in regulation of ROS are epigenetically modified, increasing ROS accumulation in retina.

•

Oxidative stress is closely associated with the pathological changes in the progress of diabetic retinopathy.

•

Antioxidants ameliorate retinopathy through targeting multiple steps of oxidative stress.

WJ-39, an Aldose Reductase Inhibitor, Ameliorates Renal Lesions in Diabetic Nephropathy by Activating Nrf2 Signaling

Diabetic nephropathy (DN) is a chronic diabetic microvascular complication. Hyperactivity of the polyol pathway is involved in the pathogenesis of DN. Aldose reductase (AR), the rate-limiting enzyme of the polyol pathway, is expected to be an effective target in the treatment of DN. WJ-39 is a novel inhibitor of AR. The present study aimed at exploring the effects of WJ-39 in DN. DN was induced in rats by injecting 30 mg/kg streptozotocin (STZ). After 14 weeks, WJ-39 (10, 20, and 40 mg/kg) was intragastrically administered to the rats for 12 weeks. Treatment with WJ-39 significantly inhibited AR activation and ameliorated renal dysfunction and fibrosis in DN rats. WJ-39 reduced oxidative stress in the kidneys of DN rats by activating the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway. WJ-39 suppressed the activation of the nuclear factor-kappa B (NF-κB) pathway and the nucleotide-binding and oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome to reduce the secretion of inflammatory factors. Rat mesangial cells (RMCs) were cultured under hyperglycemic conditions. WJ-39 abrogated the high glucose- (HG-) induced, excessive production of reactive oxygen species (ROS) and inflammatory factors. However, transfection with Nrf2 small interfering RNA abolished the effects of WJ-39. WJ-39 also blocked the transforming growth factor-β1/Smad pathway to reduce the production of glomerular extracellular matrix proteins, ultimately reducing fibrogenesis in DN. Our results show that WJ-39 ameliorated renal injury in DN rats, and its effects on oxidative stress and inflammation were associated with the activation of Nrf2 signaling. Thus, WJ-39 and its mechanism of amelioration of renal lesions in DN rats by reducing renal inflammation, oxidative stress, and fibrosis injury could be an effective strategy for the treatment of DN.

Cinnamtannin A2 protects the renal injury by attenuates the altered expression of kidney injury molecule 1 (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL) expression in 5/6 nephrectomized rat model

Present investigation determines the protective effect of Cinnamtannin A2 against chronic renal failure (CRF). 5/6 nephrectomized rat model was used to induced CRF by removing the kidneys and rats were treated with Cinnamtannin A2 10 mg/kg, i.p. for the period 30 days. Nephroprotective effect Cinnamtannin A2 was assessed by estimating the biochemical parameters of renal function test and cytokines in the serum of nephractomized rats. Oxidative stress parameters were estimated in the kidney tissue and western blot assay and qRT-PCR assay was performed to determine the expression of protein in renal tissue of nephractomized rats. Moreover histopathology study was done to observe the tubular injury. Data of the report reveals that treatment with Cinnamtannin A2 ameliorates the altered level of creatinine, blood urea nitrogen (BUN), Neutrophil gelatinase-associated lipocalin (NGAL), Kidney Injury Molecule-1 (KIM-1) and cytokines in the serum and microalbuminurea in the urine of 5/6 nephrectomized rat. Oxidative stress level was reduced in Cinnamtannin A2 treated group than CRF group. Moreover treatment with Cinnamtannin A2 attenuates the altered expression of proteins involved in Nrf2-Keap1 pathway in the kidney tissue of 5/6 nephrectomized rat. Result of histopathology reveals that tubular injury score was reduced in the kidney tissue of Cinnamtannin A2 treated group than CRF group. In conclusion, data of the report suggest that treatment with Cinnamtannin A2 ameliorates the level of KIM1 and NAGL in 5/6 nephractomized rats by regulating Nrf2- Keap1 pathway.

Mycophenolate mofetil attenuates concanavalin A-induced acute liver injury through modulation of TLR4/NF-κB and Nrf2/HO-1 pathways

BACKGROUND

Acute liver injury (ALI) is a serious health condition associated with rising morbidity and sudden progression. This study was designed to investigate the possible hepatocurative potential of two dose levels (30 and 60 mg/kg) of Mycophenolate mofetil (MMF), an immune-suppressant agent, against Concanavalin A (Con A)-induced ALI in mice.

METHOD

A single dose of Con A (20 mg/kg, IV) was used to induce ALI in mice. MMF (30 mg/kg and 60 mg/kg) was administered orally for 4 days post Con A injection.

RESULTS

MMF (30 mg/kg) failed to cause significant amelioration in Con A-induced ALI while MMF (60 mg/kg) significantly alleviated Con A-induced ALI. Administration of MMF (60 mg/kg) significantly decreased Con A-induced increase in serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels. Additionally, MMF significantly restored the disrupted oxidant/antioxidants status induced by Con A. MMF caused marked increase in hepatic nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) levels. Moreover, MMF significantly reduced Con A-induced increase in the expression of hepatic toll-like receptor 4 (TLR4), nuclear factor kappa-B (NF-κB), tumor necrosis factor-α (TNF-α), interferon-γ (INF-γ) and interleukin-1β (Il-1β). Also, MMF administration significantly decreased Con A-induced increase in the immune-expression of pro-apoptotic Bcl-2-associated X protein (Bax) and markedly increased Con A-induced decrease in the anti-apoptotic B-cell lymphoma 2 protein (Bcl2).

CONCLUSION

The observed ameliorative effect of MMF against Con A-induce ALI may be contributed to its anti-inflammatory, anti-oxidant and anti-apoptotic potentials taking into consideration that TLR4/NF-κB and Nrf2/HO-1 are the main implicated pathways. Schematic diagram summarizing the possible mechanisms underlying the ameliorative potential of Mycophenolate Mofetil against Con A-induced acute liver injury. Bax Bcl-2-associated X protein, Bcl2 B-cell lymphoma 2, MMF Mycophenolate mofetil, Con A Concanavalin A, GSH reduced glutathione, HO-1 Heme oxygenase-1, IL-1β Interleukin-1β, IFN-γ Interferon-γ, MDA Malondialdehyde, NF-κB Nuclear Factor Kappa B, Nrf2 Nuclear factor erythroid 2-related factor 2, NO Nitric Oxide, SOD Superoxide Dismutase, TLR4 Toll-like receptor 4, TNF-α tumor necrosis factor-α.

Protective effect of ferulic acid on STZ-induced diabetic nephropathy in rats

Ferulic acid protects against diabetic nephropathy in STZ-induced rats by attenuating oxidative stress, inflammation, fibrosis and podocyte injury.

Eicosapentaenoic acid prevents salt sensitivity in diabetic rats and decreases oxidative stress

OBJECTIVES

Salt sensitivity (SS) is associated with increased cardiovascular risk in patients with Type 2 diabetes mellitus (T2-DM) due to an increase in renal oxidation. ω-3 polyunsaturated fatty acids have shown antioxidant effects, but a typical Western diet contains limited content. In particular, ω-3 polyunsaturated fatty acids are able to activate nuclear factor erythroid 2-related factor 2 (Nrf-2) to prevent diabetes mellitus-related complications by mitigating oxidative stress. Therefore, we hypothesized that eicosapentaenoic acid (EPA; ω-3) modulates SS in rats with T2-DM by decreasing renal oxidative stress via Nrf-2 activation and enhancing the antiinflammatory response via interleukin (IL) 6 modulation.

METHODS

Three-month-old male rats (n = 40) were fed with a Normal Na-diet (NNaD) and randomly selected into four groups: Healthy Wistar nondiabetic rats (Wi), diabetic controls (eSS), arachidonic acid-treated eSS (AA; ω-6), and EPA-treated eSS (ω-3). After 1 year, rats were placed in metabolic cages for 7 d and fed a NNaD, followed by a 7-d period with a High Na-diet (HNaD). Systolic blood pressure, body weight, serum IL-6 and reactive oxygen species (ROS) levels were determined at the end of each 7-d period. Glycated hemoglobin (HbA1c), triacylglycerol, creatinine, and cholesterol levels were determined. ROS levels and Nrf-2 expression in kidney lysates were also assayed. Histologic changes were evaluated. A t test or analysis of variance was used for the statistical analysis.

RESULTS

After a HNaD, systolic blood pressure increased in both the control eSS and AA groups, but not in the EPA and Wi groups. However, HbA1c levels remained unchanged by the treatments, which suggests that the observed beneficial effect was independent of HbA1c levels. The IL-6 levels were higher in the eSS and AA groups, but remained unaltered in EPA and Wi rats after a HNaD diet. Interestingly, EPA protected against serum ROS in rats fed the HNaD, whereas AA did not. In kidney lysates, ROS decreased significantly in the EPA group compared with the eSS group, and Nrf-2 expression was consistently higher compared with the AA and eSS groups. Diabetic rats presented focal segmental sclerosis, adherence to Bowman capsule, and mild-to-moderate interstitial fibrosis. EPA and AA treatment prevented kidney damage.

CONCLUSIONS

An adequate ω3-to-ω6 ratio prevents SS in diabetic rats by a mechanism that is independent of glucose metabolism but associated with the prevention of renal oxidative stress generation. These data suggest that EPA antioxidant properties may prevent the development of hypertension or kidney damage.

Blockade of the Adenosine A3 Receptor Attenuates Caspase 1 Activation in Renal Tubule Epithelial Cells and Decreases Interleukins IL-1β and IL-18 in Diabetic Rats

Diabetic nephropathy (DN) is the main cause of end-stage renal disease, which remains incurable. The progression of DN is associated with progressive and irreversible renal fibrosis and also high levels of adenosine. Our aim was to evaluate the effects of ADORA3 antagonism on renal injury in streptozotocin-induced diabetic rats. An ADORA3 antagonist that was administered in diabetic rats greatly inhibited the levels of inflammatory interleukins IL-1β and IL-18, meanwhile when adenosine deaminase was administered, there was a non-selective attenuation of the inflammatory mediators IL-1β, IL-18, IL-6, and induction of IL-10. The ADORA3 antagonist attenuated the high glucose-induced activation of caspase 1 in HK2 cells in vitro. Additionally, ADORA3 antagonisms blocked the increase in caspase 1 and the nuclear localization of NFκB in the renal tubular epithelium of diabetic rats, both events that are involved in regulating the production and activation of IL-1β and IL-18. The effects of the A3 receptor antagonist resulted in the attenuation of kidney injury, as evidenced by decreased levels of the pro-fibrotic marker α-SMA at histological levels and the restoration of proteinuria in diabetic rats. We conclude that ADORA3 antagonism represents a potential therapeutic target that mechanistically works through the selective blockade of the NLRP3 inflammasome.

Nrf2 signaling attenuates epithelial-to-mesenchymal transition and renal interstitial fibrosis via PI3K/Akt signaling pathways

BACKGROUND

Nrf2 constitutes a therapeutic reference point for renal fibrosis and chronic kidney diseases. Nrf2-related signaling pathways are recognized to temper endothelial-to-mesenchymal transition (EMT) in fibrotic tissue. Nevertheless, the mechanism by which Nrf2 mitigates renal interstitial fibrosis is imprecise.

METHODS

The relationship between Nrf2 and renal interstitial fibrosis was investigated using the unilateral ureteral obstruction (UUO) model of Nrf2^-/- mice. The mice were separated into four groups, based on the treatment and intervention: Nrf2^-/- + UUO, Nrf2^-/- + Sham, WT + UUO and WT + Sham. Histological examination of renal tissue following the hematoxylin-eosin and Masson staining was carried out, as well as immunohistochemical staining. Additionally, to confirm the in vivo discoveries, in vitro experiments with HK-2 cells were also performed.

RESULTS

The Nrf2^-/- + UUO group showed more severe renal interstitial fibrosis compared to the WT + UUO, Nrf2^-/- + Sham and WT + Sham groups. Furthermore, the manifestations of α-SMA and Fibronectin significantly increased, and the manifestation of E-cadherin considerably decreased in kidney tissues from the group of Nrf2^-/- + UUO, compared to the WT + UUO group. The Nrf2 protein level significantly decreased in HK-2 cells, in reaction to the TGF-β1 concentration. In addition, the overexpression of Nrf2 presented contradictory results. What is more, the PI3K/Akt signaling pathway was discovered to be activated in the proteins extracted from cultured cells, and treated with Nrf2 siRNA and kidney tissues from the Nrf2^-/- + UUO group.

CONCLUSIONS

The results we obtained demonstrate that Nrf2 signaling pathway may perhaps offset the development of EMT, prompted by TGF-β1 and renal interstitial fibrosis. Likewise, the anti-fibrotic effect of Nrf2 was imparted by the inactivation of PI3K/Akt signaling. From our discoveries, we deliver new insight related to the prevention and treatment of kidney fibrosis.

Nrf2, a novel molecular target to reduce type 1 diabetes associated secondary complications: The basic considerations

Oxidative stress and inflammation are the mediators of diabetes and related secondary complications. Oxidative stress arises because of the excessive production of reactive oxygen species and diminished antioxidant production due to impaired Nrf2 activation, the master regulator of endogenous antioxidant. It has been established from various animal models that the transcription factor Nrf2 provides cytoprotection, ameliorates oxidative stress, inflammation and delays the progression of diabetes and its associated complications. Whereas, deletion of the transcription factor Nrf2 amplifies tissue level pathogenic alterations. In addition, Nrf2 also regulates the expression of numerous cellular defensive genes and protects against oxidative stress-mediated injuries in diabetes. The present review provides an overview on the role of Nrf2 in type 1 diabetes and explores if it could be a potential target for the treatment of diabetes and related complications. Further, the rationality of different agent's intervention has been discussed to mitigate organ damages induced by diabetes.

Immunomodulatory Effects of the Nutraceutical Garlic Derivative Allicin in the Progression of Diabetic Nephropathy

Diabetic nephropathy (DN) is presently the primary cause of chronic kidney disease and end-stage renal disease (ESRD). It has been suggested that inflammation and oxidative stress, in addition to or in concert with the metabolic changes, plays an important role in the maintenance and progression of the disease. Therefore, attenuating or blocking these mechanisms may be a therapeutic target to delay the progression of the disease. Diallyl thiosulfinate (allicin), a compound derived from garlic, inhibits free radical formation, increases glutathione synthesis and decreases the levels of proinflammatory molecules in vitro. This research aimed to assess the effect of allicin on oxidative stress and inflammation-induced diabetes. Animals were divided into control and diabetes (streptozotocin 50 mg/kg i.p.), and maintained for 30 days. After 30 days, the group of diabetic animals was subdivided into diabetes and allicin-treated diabetes (16 mg/kg/day oral gavage). The three experimental groups were maintained for another month. We analyzed the status of renal function, oxidative stress and proinflammatory cytokines. The untreated diabetic group showed hyperglycemia and increased diuresis, creatinine clearance, proteinuria, glycosuria and urinary excretion of N-acetyl-β-d-glucosaminidase (NAG), as well as increased oxidative stress and the expression of interleukin 1β (IL-1β), IL-6, nuclear factor kappa beta (NFκβ) and transforming growth factor-β1 (TGF-β1) in plasma and kidney. In contrast, the inhibitor of NFκβ (Iκβ) is decreased in the cortex. It has been demonstrated that the allicin treatment decreases hyperglycemia, polyuria, and NAG excretion. The oxidative stress and proinflammatory cytokines were also reduced by the allicin treatment. In conclusion, allicin delays the progression of diabetic nephropathy through antioxidant and anti-inflammatory mechanisms.

Remodeling of Retinal Architecture in Diabetic Retinopathy: Disruption of Ocular Physiology and Visual Functions by Inflammatory Gene Products and Pyroptosis

Diabetic patients suffer from a host of physiological abnormalities beyond just those of glucose metabolism. These abnormalities often lead to systemic inflammation via modulation of several inflammation-related genes, their respective gene products, homocysteine metabolism, and pyroptosis. The very nature of this homeostatic disruption re-sets the overall physiology of diabetics via upregulation of immune responses, enhanced retinal neovascularization, upregulation of epigenetic events, and disturbances in cells' redox regulatory system. This altered pathophysiological milieu can lead to the development of diabetic retinopathy (DR), a debilitating vision-threatening eye condition with microvascular complications. DR is the most prevalent cause of irreversible blindness in the working-age adults throughout the world as it can lead to severe structural and functional remodeling of the retina, decreasing vision and thus diminishing the quality of life. In this manuscript, we attempt to summarize recent developments and new insights to explore the very nature of this intertwined crosstalk between components of the immune system and their metabolic orchestrations to elucidate the pathophysiology of DR. Understanding the multifaceted nature of the cellular and molecular factors that are involved in DR could reveal new targets for effective diagnostics, therapeutics, prognostics, preventive tools, and finally strategies to combat the development and progression of DR in susceptible subjects.

NRF2 Activation Inhibits Both TGF-β1- and IL-13-Mediated Periostin Expression in Fibroblasts: Benefit of Cinnamaldehyde for Antifibrotic Treatment

Systemic fibrosing or sclerotic disorders are life-threatening, but only very limited treatment modalities are available for them. In recent years, periostin (POSTN), a major extracellular matrix component, was established by several studies as a novel key player in the progression of systemic fibrotic disease. In this research, we revealed the involvement of oxidative stress in the expression of POSTN induced by TGF-β1 and IL-13 in dermal fibroblasts. We found that the antioxidant cinnamaldehyde activated the NRF2/HMOX1 pathway. Cinnamaldehyde also alleviated TGF-β1- and IL-13-mediated production of reactive oxygen species and subsequent POSTN upregulation in dermal fibroblasts. In contrast, NRF2 silencing abolished the cinnamaldehyde-mediated downregulation of POSTN. These results suggest that cinnamaldehyde is a broad inhibitor of POSTN expression covering both TGF-β1 and IL-13 signaling. Cinnamaldehyde may thus be beneficial for the treatment of systemic fibrotic diseases.

Diabetic Nephropathy: a Tangled Web to Unweave

Diabetic nephropathy (DN) is currently the leading cause of end-stage renal disease globally. Given the increasing incidence of diabetes, many experts hold the view that DN will eventually progress toward pandemic proportions. Whilst hyperglycaemia-induced vascular dysfunction is the primary initiating mechanism in DN, its progression is also driven by a heterogeneous set of pathological mechanisms, including oxidative stress, inflammation and fibrosis. Current treatment strategies for DN are targeted against the fundamental dysregulation of glycaemia and hypertension. Unfortunately, these standards of care can delay but do not prevent disease progression or the significant emotional, physical and financial costs associated with this disease. As such, there is a pressing need to develop novel therapeutics that are both effective and safe. Set against the genomic era, numerous potential target pathways in DN have been identified. However, the clinical translation of basic DN research has been met with a number of challenges. Moreover, the notion of DN as a purely vascular disease is outdated and it has become clear that DN is a multi-dimensional, multi-cellular condition. The review will highlight the current therapeutic approaches for DN and provide an insight into how the inherent complexity of DN is shaping the research pathways toward the development and clinical translation of novel therapeutic strategies.

Extracellular Superoxide Dismutase Attenuates Renal Oxidative Stress Through the Activation of Adenosine Monophosphate-Activated Protein Kinase in Diabetic Nephropathy

AIMS

Oxidative stress plays a crucial role in the pathogenesis of diabetic nephropathy (DN). We evaluated whether extracellular superoxide dismutase (EC-SOD) has a renoprotective effect through activation of adenosine monophosphate-activated protein kinase (AMPK) in diabetic kidneys.

RESULTS

Human recombinant EC-SOD (hEC-SOD) was administered to 8-week-old male C57BLKS/J db/db mice through intraperitoneal injection once a week for 8 weeks. Renal SOD3 expression was suppressed in db/db mice, which was significantly enhanced by hEC-SOD treatment. hEC-SOD improved albuminuria, mesangial expansion, and interstitial fibrosis in db/db mice. At the molecular level, hEC-SOD increased phosphorylation of AMPK, activation of peroxisome proliferative-activated receptor γ coactivator 1α (PGC-1α), and dephosphorylation of forkhead box O transcription factor (FoxO)1 and FoxO3a. The protective effects of hEC-SOD were attributed to enhanced nuclear translocation of nuclear factor E2-related factor 2 (Nrf2) and subsequently increased expression of NAD(P)H dehydrogenase 1 and heme oxygenase-1. Consequently, hEC-SOD recovered from systemic and renal inflammation and apoptosis, as reflected by the decreases of serum and renal monocyte chemoattractant protein-1 and tumor necrosis factor-α levels and increases of BCL-2/BAX ratio in diabetic kidney. hEC-SOD also improved oxidative stress and resulted in increased renal and urinary 8-hydroxy-2'-deoxyguanosine and 8-isoprostane levels in db/db mice. In cultured human glomerular endothelial cells, hEC-SOD ameliorated apoptosis and oxidative stress caused by high glucose exposure through activation of AMPK and PGC-1α and dephosphorylation of FoxOs.

INNOVATION

These findings demonstrated for the first time that EC-SOD can potentially ameliorate hyperglycemia-induced oxidative stress, apoptosis, and inflammation through activation of AMPK and its downstream pathways in diabetic kidneys.

CONCLUSIONS

EC-SOD is a potential therapeutic target for treatment of type 2 DN through intrarenal AMPK-PGC-1α-Nrf2 and AMPK-FoxOs signaling. Antioxid. Redox Signal. 28, 1543-1561.

Paeonol Ameliorates Diabetic Renal Fibrosis Through Promoting the Activation of the Nrf2/ARE Pathway via Up-Regulating Sirt1

Diabetic nephropathy (DN) is rapidly becoming the leading cause of end-stage renal disease worldwide and a major cause of morbidity and mortality in patients of diabetes. The main pathological change of DN is renal fibrosis. Paeonol (PA), a single phenolic compound extracted from the root bark of Cortex Moutan, has been demonstrated to have many potential pharmacological activities. However, the effects of PA on DN have not been fully elucidated. In this study, high glucose (HG)-treated glomerular mesangial cells (GMCs) and streptozotocin (STZ)-induced diabetic mice were analyzed in exploring the potential mechanisms of PA on DN. Results in vitro showed that: (1) PA inhibited HG-induced fibronectin (FN) and ICAM-1 overexpressions; (2) PA exerted renoprotective effect through activating the Nrf2/ARE pathway; (3) Sirt1 mediated the effects of PA on the activation of Nrf2/ARE pathway. What is more, in accordance with the in vitro results, significant elevated levels of Sirt1, Nrf2 and downstream proteins related to Nrf2 were observed in the kidneys of PA treatment group compared with model group. Taken together, our study shows that PA delays the progression of diabetic renal fibrosis, and the underlying mechanism is probably associated with regulating the Nrf2 pathway. The effect of PA on Nrf2 is at least partially dependent on Sirt1 activation.

Troxerutin Reduces Kidney Damage against BDE-47-Induced Apoptosis via Inhibiting NOX2 Activity and Increasing Nrf2 Activity

2,2,4,4-Tetrabromodiphenyl ether (BDE-47), one of the persistent organic pollutants, seriously influences the quality of life; however, its pathological mechanism remains unclear. Troxerutin is a flavonoid with pharmacological activity of antioxidation and anti-inflammation. In the present study, we investigated troxerutin against BDE-47-induced kidney cell apoptosis and explored the underlying mechanism. The results show that troxerutin reduced renal cell apoptosis and urinary protein secretion in BDE-47-treated mice. Western blot analysis shows that troxerutin supplement enhanced the ratio of Bcl-2/Bax; inhibited the release of cytochrome c from mitochondria, the activation of procaspase-9 and procaspase-3, and the cleavage of PARP; and reduced FAS, FASL, and caspase-8 levels induced by BDE-47. In addition, troxerutin decreased the production of reactive oxygen species (ROS) and increased the activities of antioxidative enzymes. Furthermore, troxerutin blunted Nrf2 ubiquitylation, enhanced the activity of Nrf2, decreased the activity of NOX2, and ameliorated kidney oxidant status of BDE-47-treated mice. Together, these results confirm that troxerutin could alleviate the cytotoxicity of BDE-47 through antioxidation and antiapoptosis, which suggests that its protective mechanism is involved in the inhibition of apoptosis via suppressing NOX2 activity and increasing Nrf2 signaling pathway.

A pilot study evaluating changes to haematological and biochemical tests after Flexible Ureterorenoscopy for the treatment of kidney stones

BACKGROUND

Currently there is limited research documenting the changes in blood parameters, following Flexible Ureterorenoscopy. This study aims to determine whether there are any changes in haematology and biochemistry parameters, following Flexible Ureterorenoscopy for the treatment of kidney stones.

METHODS

40 consecutive patients aged between 27-87 years (median 49 years) undergoing Flexible Ureterorenoscopy for the treatment of kidney stones were recruited (26 male, 14 female). Blood samples were collected from each patient at four time points: baseline (pre-operatively) followed by 30 minutes, 120 minutes and 240 minutes post-operatively. On these samples, routine haematological and biochemistry tests were carried out. In addition to the assessment of clinical parameters prospectively from the medical notes.

RESULTS

There was a significant decrease observed following Flexible Ureterorenoscopy in the following parameters: lymphocytes (p = 0.007), eosinophils (p = 0.001), basophils (p = 0.001), haemoglobin (p = 0.002), red blood cells (p = 0.001), platelet count (p = 0.001), fibrinogen concentration (p = 0.001), von Willebrand factor (p = 0.046), C reactive protein (p = 0.01), total protein (p = 0.001), albumin (p = 0.001), globulin (p = 0.001) and alkaline phosphatase (p = 0.001). In addition, there was a significant increase observed in the following parameters: white blood cells (p = 0.001), neutrophils (p = 0.001), activated partial thromboplastin time (p = 0.001), total bilirubin (p = 0.012), creatinine (p = 0.008), sodium (p = 0.002) and potassium (p = 0.001). Limiting factors for this study were the sample size, and restriction on the recruitment time points.

CONCLUSIONS

Significant changes were noted to occur in haematology and biochemistry parameters following Flexible Ureterorenoscopy. Some of the data presented in this study may represent the 'normal' post-operative response following FURS, as no major complications occurred, in the majority of our patients. This data on the 'normal response' will need to be validated but may ultimately aid clinicians in distinguishing patients at risk of complications, if reproduced in larger multi-centre studies.

Oxidative Stress-Related Mechanisms and Antioxidant Therapy in Diabetic Retinopathy

Diabetic retinopathy (DR) is one of the most common microvascular complications of diabetes and is the leading cause of blindness in young adults. Oxidative stress has been implicated as a critical cause of DR. Metabolic abnormalities induced by high-glucose levels are involved in the development of DR and appear to be influenced by oxidative stress. The imbalance between reactive oxygen species (ROS) production and the antioxidant defense system activates several oxidative stress-related mechanisms that promote the pathogenesis of DR. The damage caused by oxidative stress persists for a considerable time, even after the blood glucose concentration has returned to a normal level. Animal experiments have proved that the use of antioxidants is a beneficial therapeutic strategy for the treatment of DR, but more data are required from clinical trials. The aims of this review are to highlight the improvements to our understanding of the oxidative stress-related mechanisms underlying the development of DR and provide a summary of the main antioxidant therapy strategies used to treat the disease.

Role of Nuclear Factor Erythroid 2-Related Factor 2 in Diabetic Nephropathy

Diabetic nephropathy (DN) is manifested as increased urinary protein level, decreased glomerular filtration rate, and final renal dysfunction. DN is the leading cause of end-stage renal disease worldwide and causes a huge societal healthcare burden. Since satisfied treatments are still limited, exploring new strategies for the treatment of this disease is urgently needed. Oxidative stress takes part in the initiation and development of DN. In addition, nuclear factor erythroid 2-related factor 2 (Nrf2) plays a key role in the cellular response to oxidative stress. Thus, activation of Nrf2 seems to be a new choice for the treatment of DN. In current review, we discussed and summarized the therapeutic effects of Nrf2 activation on DN from both basic and clinical studies.

New Pathogenic Concepts and Therapeutic Approaches to Oxidative Stress in Chronic Kidney Disease

In chronic kidney disease inflammatory processes and stimulation of immune cells result in overproduction of free radicals. In combination with a reduced antioxidant capacity this causes oxidative stress. This review focuses on current pathogenic concepts of oxidative stress for the decline of kidney function and development of cardiovascular complications. We discuss the impact of mitochondrial alterations and dysfunction, a pathogenic role for hyperuricemia, and disturbances of vitamin D metabolism and signal transduction. Recent antioxidant therapy options including the use of vitamin D and pharmacologic therapies for hyperuricemia are discussed. Finally, we review some new therapy options in diabetic nephropathy including antidiabetic agents (noninsulin dependent), plant antioxidants, and food components as alternative antioxidant therapies.

Mycophenolate mofetil and curcumin provide comparable therapeutic benefit in experimental chronic kidney disease: role of Nrf2-Keap1 and renal dopamine pathways

Increased oxidative stress and inflammation have an important role in the pathophysiology of chronic kidney disease (CKD). On the other hand, more affordable therapeutic alternatives for treating this disease are urgently needed. Therefore, we compared the therapeutic efficacy of curcumin and mycophenolate mofetil (MMF) in 5/6 nephrectomy (5/6 Nx) model of CKD. Also, we evaluated whether both compounds provide benefit through the preservation of similar antioxidant mechanisms. Four groups of male Wistar were studied over a period of 4 wk. Control sham group (n= 12), 5/6 Nx (n = 12), 5/6 Nx + MMF (30 mg/k BW/day, n = 11) and 5/6 Nx + Curcumin (120 mg/k BW/day, n = 12). Renal function and markers of oxidative stress and inflammation were evaluated. Also Nrf2-Keap1 and renal dopamine, antioxidant pathways were assessed. 5/6 Nx induced an altered renal autoregulation response, proteinuria, and hypertension; these effects were in association with increased oxidative stress, endothelial dysfunction and renal inflammation. The mechanisms associated with these alterations included a reduced nuclear translocation of Nrf2 and hyperphosphorylation of dopamine D1 receptor with a concurrent overactivation of renal NADPH oxidase. Treatments with MMF and curcumin provided equivalent therapeutic efficacy as both prevented functional renal alterations as well as preserved antioxidant capacity and avoided renal inflammatory infiltration. Moreover, both treatments preserved Nrf2-Keap1 and renal dopamine antioxidant pathways. In summary, therapeutic strategies aimed to preserve renal antioxidant pathways can help to retard the progression of CKD.