Structured DAG oil ameliorates renal injury in streptozotocin-induced diabetic rats through inhibition of NF-κB and activation of Nrf2 pathway

The impact of chitooligosaccharides with a certain degree of polymerization on diabetic nephropathic mice and high glucose-damaged HK-2 cells

Diabetic nephropathy (DN) is a primary diabetic complication ascribed to the pathological changes in renal microvessels. This study investigated the nuclear factor erythroid 2-related factor 2 (Nrf2)/Kelch ECH associating protein (Keap1)/antioxidant response element (ARE) signaling pathway impact of chitooligosaccharides (COS) with a certain degree of polymerization (DP) on DN mouse models and high glucose-damaged human kidney 2 (HK-2) cells. The findings indicated that COS effectively reduced the renal function indexes (uric acid [UA], urinary albumin excretion rate [UAER], urine albumin-to-creatinine ratio [UACR], blood urea nitrogen [BUN], and creatinine [Cre]) of DN mice. It increased (p < .05) the superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) antioxidant enzyme activity in the serum and kidneys, and decreased (p < .05) the malondialdehyde (MDA) content. The mechanistic investigation showed that COS significantly increased (p < .05) Nrf2 and downstream target gene (GCLM, GCLC, HO-1, and NQO-1) expression, and substantially decreased (p < .05) Keap1 expression. The protein level was consistent with the messenger RNA (mRNA) level in in vitro and in vivo models. The docking data indicated that COS and Keap1 protein binding included six hydrogen bond formation processes (Gly364, Arg415, Arg483, His436, Ser431, and Arg380). The COS intervention mechanism may be related to the Nrf2/Keap1/ARE antioxidant pathway. Therefore, it provides a scientific basis for COS application in developing special medical food for DN patients.

Nrf2 signaling in diabetic nephropathy, cardiomyopathy and neuropathy: Therapeutic targeting, challenges and future prospective

Western lifestyle contributes to an overt increase in the prevalence of metabolic anomalies including diabetes mellitus (DM) and obesity. Prevalence of DM is rapidly growing worldwide, affecting many individuals in both developing and developed countries. DM is correlated with the onset and development of complications with diabetic nephropathy (DN), diabetic cardiomyopathy (DC) and diabetic neuropathy being the most devastating pathological events. On the other hand, Nrf2 is a regulator for redox balance in cells and accounts for activation of antioxidant enzymes. Dysregulation of Nrf2 signaling has been shown in various human diseases such as DM. This review focuses on the role Nrf2 signaling in major diabetic complications and targeting Nrf2 for treatment of this disease. These three complications share similarities including the presence of oxidative stress, inflammation and fibrosis. Onset and development of fibrosis impairs organ function, while oxidative stress and inflammation can evoke damage to cells. Activation of Nrf2 signaling significantly dampens inflammation and oxidative damage, and is beneficial in retarding interstitial fibrosis in diabetic complications. SIRT1 and AMPK are among the predominant pathways to upregulate Nrf2 expression in the amelioration of DN, DC and diabetic neuropathy. Moreover, certain therapeutic agents such as resveratrol and curcumin, among others, have been employed in promoting Nrf2 expression to upregulate HO-1 and other antioxidant enzymes in the combat of oxidative stress in the face of DM.

Manjari Medika Grape Seed Extract Protects Methotrexate-Induced Hepatic Inflammation: Involvement of NF-κB/NLRP3 and Nrf2/HO-1 Signaling System

Objective

Grape Seed Extract is a natural source of various polyphenols, which have been shown to possess potent antioxidant and free radical-scavenging activities. The earlier studies have reported that grape seed extract exhibits broad-spectrum pharmacological activities. Therefore, studying the hepatoprotective effects and elucidation of mechanisms of action of the Indian Variety, Manjari Medika grape seed extract (GSE), may give an insight into therapeutic benefits. Methotrexate (MTX) is the first-line pharmacological therapy for different rheumatic diseases. The major adverse events such as hepatotoxicity are evident even in the low doses used for the treatment. The present study investigated the role of MTX on hepatic damage in murine liver and the plausible protective effects of the Indian grape variety, Manjari Medika grape seed extract, in ameliorating it.

Methods and Results

To assess the hepatological modulation, mice were divided into eight groups to investigate the ameliorative potential of this GSE (75 and 125 mg/kg) and correlate the experimental findings. The active components of the extract were assessed through UPLC-(ESI)-QToF-MS analysis. On the other hand, various biochemical and immunological indices were carried out to correlate the experimental data. The result demonstrated that the prophylactic administration of GSE reduced MTX-induced hepatic toxicity indices, which subsequently restored the hepatic morphological architecture. Moreover, the application of GSE in a dual dosage (75 and 125 mg/kg) suppressed MTX-induced reactive oxygen species generation, followed by lipid peroxidation and cellular nitrite formation. MTX-induced inflammasome activation through the redox-assisted cascade of TLR4/NF-κB signaling was further reduced by applying the GSE. The results showed that the activation of cytoprotective transcription factor Nrf2 enhanced the level of endogenous antioxidants. Furthermore, through the regulation of TLR4/NF-κB and Nrf2/HO-1 axis, this extract could reduce the MTX-mediated hepatic damage.

Conclusion

Our findings suggest that Manjari Medika seed extract could be used as a therapeutic agent to relieve the side effects of MTX and other hepatic disorders.

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.

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.

MicroRNA-451 inhibits inflammation and proliferation of glomerular mesangial cells through down-regulating PSMD11 and NF-κB p65

The present study aimed to investigate the regulatory roles of microRNA-451 (miR-451) on the inflammation and proliferation of glomerular mesangial cells (GMCs) under high-glucose condition, and reveal the potential mechanisms related to 26S proteasome non-ATPase regulatory subunit 11 (PSMD11) and nuclear factor-κ B (NF-κB) signaling. The interaction between PSMD11 and miR-451 was identified by dual luciferase reporter (DLR) gene assay. GMCs were treated with 5.6 mmol/l (normal, L-GMCs) and 30 mmol/l glucose (high-glucose, H-GMCs), respectively. After transfecting with pcDNA3.1-PSMD11 and/or miR-451 mimics, the expression of miR-451, PSMD11, inhibitor of NF-κB α (IκBα), phosphorylated IκBα (p-IκBα), NF-κB p65, COX-2, and cyclinD1 were detected in H-GMCs by quantitative real-time PCR (qRT-PCR) and/or Western blot. The levels of interleukin (IL)-1β, IL-6, and IL-8, cell cycle, and viability was detected by enzyme-linked immunosorbent assay, flow cytometry, and MTT assay, respectively. MiR-451 was up-regulated in H-GMCs, and negatively regulated its target PSMD11 (P<0.05). H-GMCs exhibited significantly higher levels of IL-1β, IL-6, and IL-8, cell viability, and p-IκBα, NF-κB, COX-2, and cyclinD1 expression than L-GMCs (P<0.05). The transfection of miR-451 mimics significantly decreased the levels of IL-1β, IL-6, and IL-8, inhibited the cell viability via blocking cells in G0/G1 phase, and down-regulated p-IκBα, NF-κB p65, COX-2, and cyclinD1 in H-GMCs (P<0.05). The regulatory effects of miR-451 mimics on H-GMCs were reversed by the transfection of PSMD11 (P<0.05). The up-regulation of miR-451 inhibits the inflammation and proliferation of H-GMCs through down-regulating PSMD11 and NF-κB p65.

Amelioration of diabetic nephropathy using pomegranate peel extract-stabilized gold nanoparticles: assessment of NF-κB and Nrf2 signaling system

Background

Diabetic nephropathy (DN), an end-stage renal disorder, has posed a menace to humankind globally, because of its complex nature and poorly understandable intricate mechanism. In recent times, functional foods as potential health benefits have been gaining attention of consumers and researchers alike. Rich in antioxidants, the peel and seed of pomegranate have previously demonstrated protection against oxidative-stress-related diseases, including cardiovascular disorders, diabetes, and cancer.

Purpose

This study was designed to investigate the ameliorative role of pomegranate peel extract–stabilized gold nanoparticle (PPE-AuNP) on streptozotocin (STZ)-induced DN in an experimental murine model.

Methods

Following the reduction methods, AuNP was prepared using the pomegranate peel ellagitannins and characterized by particle size, physical appearance, and morphological architecture. Modulatory potential of PPE-AuNP was examined through the plethora of biochemical and high throughput techniques, flow cytometry, immunoblotting, and immunofluorescence.

Results

The animals treated with PPE-AuNP markedly reduced the fasting blood glucose, renal toxicity indices, and serum TC and TG in a hyperglycemic condition. As evident from an increased level of plasma insulin level, PPE-AuNP normalized the STZ-induced pancreatic β-cell dysfunction. The STZ-mediated suppression of endogenous antioxidant response was restored by the PPE-AuNP treatment, which reduced the generation of LPO as well as iROS. Furthermore, the hyperglycemia-mediated augmentation of protein glycation, followed by the NOX4/p-47^phox activation, diminished with the application of PPE-AuNP. The histological and immunohistochemical findings showed the protective efficacy of PPE-AuNP in reducing STZ-induced glomerular sclerosis and renal fibrosis. In addition, it reduced proinflammatory burden through the modulation of the MAPK/NF-κB/STAT3/cytokine axis. Simultaneously, PI3K/AKT-guided Nrf2 activation was evident upon the PPE-AuNP application, which enhanced the antioxidant response and maintained hyperglycemic homeostasis.

Conclusion

The findings indicate that the use of PPE-AuNPs might act as an economic therapeutic remedy for alleviating DN.

Tender coconut water attenuates heat stress-induced testicular damage through modulation of the NF-κB and Nrf2 pathways

Tender coconut water (TCW), a well-known plant beverage, has been used as a stress-relieving traditional medicine since ancient times. It is also used to treat various ailments of disease, including hepatic disorders, renal disorders, gastric disorders and reproductive disorders. However, the reasons for its effectiveness as a natural antioxidant as well as its testicular protective effects against whole body heat stress (HS)-induced oxidative imbalance remain to be revealed. The present study aimed to elucidate the protective efficacy of TCW on HS-induced testicular damage in a murine system and to explore the possible mechanism of action. Standardized liquid chromatography-mass spectrometry (LC-MS) was used to detect the presence of active components in TCW. Male Wistar rats were exposed to acute HS with or without TCW treatment to evaluate the degree of testicular damage, which was monitored through histological as well as biochemical analysis. Assessment of endogenous antioxidant response and the modulation of signaling pathways associated with inflammation were also subjected to immunofluorescence and flow cytometric evaluation. Acute hyperthermia caused an elevation of excess generation of oxygen radicals following the suppression of antioxidant capacity and augmentation of lipid peroxidation in murine testicles, which was restored by treatment with TCW. The results also demonstrated marked phosphorylation of IKKα/β and IκBα following the activation of NF-κB-guided pro-inflammation upon HS. TCW treatment reversed the HS-induced proinflammatory state through activation of the Nrf2-assisted antioxidant response, which restored the testicular damage. TCW provided competent scientific evidence to substantiate the claims for its use in the treatment of HS-induced inflammation and inflammation-mediated testicular damage.

Bicyclol Attenuates Liver Inflammation Induced by Infection of Hepatitis C Virus via Repressing ROS-Mediated Activation of MAPK/NF-κB Signaling Pathway

Treatment with direct-acting antivirals (DAAs) cures most patients infected with hepatitis C virus (HCV) in the real world. However, some patients, especially those with the underlying advanced liver disease, have a limited reduction of liver injury after achieving a sustained viral response (SVR). Bicyclol was widely used in clinics for the treatment of a variety of liver injuries but with an unknown mechanism for the treatment of hepatitis C. We investigated the anti-inflammatory effects and mechanisms of bicyclol in HCV-infected hepatocytes and further confirmed the putative results in a mouse hepatitis model induced by the coinjection of polyinosinic-polycytidylic acid [poly (I:C)] and D-galactosamine (D-GalN). The results showed that the activation of nuclear factor kappa B (NF-κB) and the subsequent increase of inflammatory factors were directly induced by HCV infection and were persistent after clearance of the virus in Huh7.5 cells. Bicyclol decreased the activation of NF-κB and the levels of inflammatory factors in HCV-infected hepatocytes by inhibiting the activation of the ROS-MAPK-NF-κB pathway, and the effect was synergistic with DAAs in HCV-infected hepatocytes. Bicyclol attenuated the ROS-MAPK-NF-κB axis via recovering mitochondrial function without a dependence on dihydronicotinamide adenine dinucleotide phosphate oxidase and superoxide dismutases. The anti-inflammatory effects and mechanism of bicyclol were verified in mouse hepatitis induced by the coinjection of poly(I:C)/D-GalN. Bicyclol directly ameliorates the chronic inflammation caused by HCV infection and might be used with DAAs or after DAA therapy for ultimately curing chronic hepatitis C.

Dexpanthenol reduces diabetic nephropathy and renal oxidative stress in rats

Hyperglycemia increases reactive oxygen species (ROS) and the resulting oxidative stress contributes to the development of diabetic complications. Dexpanthenol (Dxp) is the biological active form of pantothenic acid. We investigated whether Dxp administration could decrease oxidative stress as a way to treat renal complications of diabetes mellitus (DM). Thirty-two male Wistar albino rats were divided into four groups: control, Dxp, DM and DM + Dxp. Experimental diabetes was induced by a single dose of streptozotocin (STZ). After administration of STZ, the DM + Dxp group was administered 500 mg/kg Dxp intraperitoneally every day for 6 weeks. At the end of the study, blood glucose levels were measured and rats were sacrificed. Kidneys were embedded in paraffin, sectioned and stained with hematoxylin and eosin, and periodic acid-Schiff. The mean malondialdehyde levels, glutathione peroxidase, superoxide dismutase and catalase activities, and total antioxidant and total oxidant status also were measured. The control group was normal in histological appearance. We observed congestion, inflammation, glomerulosclerosis, tubular desquamation, loss of villi and hydropic degeneration in tubule cells in the DM group. Indicators of oxidative stress were elevated and antioxidant activity was reduced in the DM group compared to controls. In the DM + Dxp group, oxidative stress was decreased, antioxidant activity was increased and histopathological changes were reduced compared to the DM group. We found that Dxp exhibited ameliorative effects on STZ induced diabetic nephropathy by increasing antioxidant activity.

The Nrf2/HO-1 Pathway Mediates the Antagonist Effect of L-Arginine On Renal Ischemia/Reperfusion Injury in Rats

BACKGROUND/AIMS

Ischemia/reperfusion (I/R) is the most common cause of acute renal injury. I/R-induced oxidative stress is involved in the development of acute renal injury, which can be reversed by supplementation with L-arginine, a precursor of nitric oxide (NO). This study was conducted to evaluate alterations in the expression of transcription factors [nuclear factor kappa B (NF-κB), nuclear factor-E2-related factor-2 (Nrf2), and heme oxygenase 1 (HO-1)] and heat shock protein 70 (HSP70) in the kidney of I/R-induced injury rats.

METHODS

Sprague-Dawley (SD) rats were subjected to bilateral renal ischemia for 45 min followed by reperfusion for 24 h. Group 1, Sham; group 2, I/R; group 3, L-arginine; and group 4, L-arginine+zinc protoporphyrin (ZnPP). The levels of serum creatinine (Scr), blood urea nitrogen (BUN), serum nitric oxide (NO), histic malondialdehyde (MDA) and reactive oxygen species (ROS) and superoxide dismutase (SOD) activity were determined, and the expression levels of Nrf2, HO-1, NF-κB, and HSP70 were evaluated.

RESULTS

The treatment of rats with L-arginine produced a significant reduction in the levels of BUN, Scr, MDA and a significant enhancement in the level of NO and in the activity of SOD compared to renal I/R groups. The expression levels of Nrf2, HO-1, and HSP70 were strongly increased, and the expression of NF-κB and production of ROS were significantly decreased in the L-arginine group compared to that of the I/R group. ZnPP increased renal damage and displayed effects opposite to those of L-arginine.

CONCLUSION

These findings suggested that L-arginine/NO reduces renal dysfunction associated with I/R of the kidney and may act as a trigger to regulate the NF-κB, HSP70 and Nrf2/HO-1 signaling cascades.

Treatment combining aliskiren with paricalcitol is effective against progressive renal tubulointerstitial fibrosis via dual blockade of intrarenal renin

The aim of this study was to assess any potential additive effects of a treatment combining aliskiren with paricalcitol on reducing renal fibrosis. C57BL/6J mice were treated individually with aliskiren and/or paricalcitol until 7 days after initiation of unilateral ureteral obstruction (UUO).In obstructed kidneys of UUO mice, monotherapy with aliskiren or paricalcitol significantly attenuated interstitial fibrosis, collagen IV accumulation, and α-smooth muscle actin- and terminal deoxynucleotidyl transferase-mediated biotin nick end-labeling-positive cells. The combination treatment showed additive efficacy in inhibition of these parameters. Renal NADPH oxidase (Nox)1 and Nox2 were significantly decreased by aliskiren or paricalcitol alone or in combination, while renal Nox4 expression was significantly reduced by paricalcitol mono- or combination treatment. Increased levels of p-Erk and p-p38 MAPK, and NF-κB in UUO kidneys were also significantly reduced by either aliskiren or paricalcitol treatment alone or in combination. Aliskiren or paricalcitol monotherapy significantly reduced the expression of (pro)renin receptor in UUO kidneys. In addition, aliskiren tended to augment renin expression in UUO kidneys, but paricalcitol reduced its expression level. The combination treatment effectively blocked both (pro)renin receptor and renin expression induced by aliskiren, and resulted in a further reduction of the renal expression of angiotensin II AT1 receptor. Aliskiren failed to increase the expression of vitamin D receptor in UUO kidneys, but the combination treatment restored its expression level. Taken together, a treatment combining aliskiren with paricalcitol better inhibits UUO-induced renal injury. The mechanism of this synergy may involve more profound inhibition of the intrarenal renin-angiotensin system.