The role of DJ-1/Nrf2 pathway in the pathogenesis of diabetic nephropathy in rats

DJ-1 preserves ischemic postconditioning-induced cardioprotection in STZ-induced type 1 diabetic rats: role of PTEN and DJ-1 subcellular translocation

BACKGROUND

Ischemic postconditioning (IPostC) has been reported as a promising method for protecting against myocardial ischemia-reperfusion (MI/R) injury. Our previous study found that the infarct-limiting effect of IPostC is abolished in the heart of diabetes whose cardiac expression of DJ-1 (also called PARK7, Parkinsonism associated deglycase) is reduced. However, the role and in particular the underlying mechanism of DJ-1 in the loss of sensitivity to IPostC-induced cardioprotection in diabetic hearts remains unclear.

METHODS

Streptozotocin-induced type 1 diabetic rats were subjected to MI/R injury by occluding the left anterior descending artery (LAD) and followed by reperfusion. IPostC was induced by three cycles of 10s of reperfusion and ischemia at the onset of reperfusion. AAV9-CMV-DJ-1, AAV9-CMV-C106S-DJ-1 or AAV9-DJ-1 siRNA were injected via tail vein to either over-express or knock-down DJ-1 three weeks before inducing MI/R.

RESULTS

Diabetic rats subjected to MI/R exhibited larger infarct area, more severe oxidative injury concomitant with significantly reduced cardiac DJ-1 expression and increased PTEN expression as compared to non-diabetic rats. AAV9-mediated cardiac DJ-1 overexpression, but not the cardiac overexpression of DJ-1 mutant C106S, restored IPostC-induced cardioprotection and this effect was accompanied by increased cytoplasmic DJ-1 translocation toward nuclear and mitochondrial, reduced PTEN expression, and increased Nrf-2/HO-1 transcription. Our further study showed that AAV9-mediated targeted DJ-1 gene knockdown aggravated MI/R injury in diabetic hearts, and this exacerbation of MI/R injury was partially reversed by IPostC in the presence of PTEN inhibition or Nrf-2 activation.

CONCLUSIONS

These findings suggest that DJ-1 preserves the cardioprotective effect of IPostC against MI/R injury in diabetic rats through nuclear and mitochondrial DJ-1 translocation and that inhibition of cardiac PTEN and activation of Nrf-2/HO-1 may represent the major downstream mechanisms whereby DJ-1 preserves the cardioprotective effect of IPostC in diabetes.

The Effects of Apigenin in the Treatment of Diabetic Nephropathy: A Systematic Review of Non-clinical Studies

PURPOSE

Diabetes is one of the important and growing diseases in the world. Among the most common diabetic complications are renal adverse effects. The use of apigenin may prevent the development and progression of diabetes-related injuries. The current study aims to review the effects of apigenin in the treatment of diabetic nephropathy.

METHODS

In this review, a systematic search was performed based on PRISMA guidelines for obtaining all relevant studies on "the effects of apigenin against diabetic nephropathy" in various electronic databases up to September 2022. Ninety-one articles were obtained and screened in accordance with the predefined inclusion and exclusion criteria. Seven eligible articles were finally included in this review.

RESULTS

The experimental findings revealed that hyperglycemia led to the decreased cell viability of kidney cells and body weight loss and an increased kidney weight of rats; however, apigenin administration had a reverse effect on these evaluated parameters. It was also found that hyperglycemia could induce alterations in the biochemical and renal function-related parameters as well as histopathological injuries in kidney cells or tissue; in contrast, the apigenin administration could ameliorate the hyperglycemia-induced renal adverse effects.

CONCLUSION

The results indicated that the use of apigenin could mitigate diabetes-induced renal adverse effects, mainly through its antioxidant, anti-apoptotic, and anti-inflammatory activities. Since the findings of this study are based on experimental studies, suggesting the use of apigenin (as a nephroprotective agent) against diabetic nephropathy requires further clinical studies.

Park7 protects retinal ganglion cells and promotes functional preservation after optic nerve crush via regulation of the Nrf2 signaling pathway

PURPOSE

We aim to investigate the effect of Park7 on mice RGC survival and function following optic nerve crush (ONC), and to explore its potential mechanism.

METHODS

Wild-type male C57BL/6J mice were subjected to optic nerve crush. Six weeks before ONC, mice received rAAV-shRNA (Park7)-EGFP or rAAV-EGFP intravitreally. Western blotting was used to detect Park7 levels. RGC survival was measured using immunofluorescence. Retinal cell apoptosis was detected using terminal deoxynucleotidyl transferase nick-end-labelling. An electroretinogram (ERG) and the optomotor response (OMR) were used to assess RGC function. Kelch-like ECH-associated protein 1 (Keap1), nuclear factor erythroid 2-related factor (Nrf2), and heme oxygenase 1 (HO-1) levels were assessed using western blotting.

RESULTS

ONC injury increased the relative expression of Park7 significantly and decreased RGC survival, the amplitude of the photopic negative response (PhNR), and OMR. Intravitreal injection of rAAV-shRNA(Park7)-EGFP downregulated Park7 expression and was clearly demonstrated by the green fluorescence protein in many retinal layers. Moreover, Park7 downregulation aggravated the decrease in RGC survival and amplitude of PhNR as well as the visual acuity after ONC. However, inhibition of Park7 significantly increased Keap1 levels, decreased the total and nuclear Nrf2 levels, and reduced HO-1 levels.

CONCLUSIONS

Park7 downregulation enhanced RGC injury and decreased retinal electrophysiological response and OMR after ONC in mice via the Keap1-Nrf2-HO-1 signaling pathway. Park7 may have neuroprotective effects and could represent a novel way to treat optic neuropathy.

Astragaloside IV attenuates podocyte apoptosis through ameliorating mitochondrial dysfunction by up-regulated Nrf2-ARE/TFAM signaling in diabetic kidney disease

Defective antioxidant system as well as mitochondrial dysfunction contributes to the pathogenesis and progression of diabetic kidney disease (DKD). Nuclear factor erythroid 2-related factor 2 (Nrf2)-mediated signaling is the central defensive mechanism against oxidative stress and therefore pharmacological activation of Nrf2 is a promising therapeutic strategy. In this study, using molecular docking we found that Astragaloside IV (AS-IV), an active ingredient from traditional formula of Huangqi decoction (HQD), exerted a higher potential to promote Nrf2 escape from Keap1-Nrf2 interaction via competitively bind to amino acid sites in Keap1. When podocyte exposed to high glucose (HG) stimulation, mitochondrial morphological alterations and podocyte apoptosis were presented and accompanied by Nrf2 and mitochondrial transcription factor A (TFAM) downregulation. Mechanistically, HG promoted a decrease in mitochondria-specific electron transport chain (ETC) complexes, ATP synthesis and mtDNA content as well as increased ROS production. Conversely, all these mitochondrial defects were dramatically alleviated by AS-IV, but suppression of Nrf2 with inhibitor or siRNA and TFAM siRNA simultaneously alleviated the AS-IV efficacy. Moreover, experimental diabetic mice exhibited significant renal injury as well as mitochondrial disorder, corresponding with the decreased expression of Nrf2 and TFAM. On the contrary, AS-IV reversed the abnormality and the Nrf2 and TFAM expression were also restored. Taken together, the present findings demonstrate the improvement of AS-IV on mitochondrial function, thereby resistance to oxidative stress-induced diabetic kidney injury and podocyte apoptosis, and the process is closely associated with activation of Nrf2-ARE/TFAM signaling.

Interval training and Crataegus persica ameliorate diabetic nephropathy via miR-126/Nrf-2 mediated inhibition of stress oxidative in rats with diabetes after myocardial ischemia-reperfusion injury

Myocardial disorders are the most common cause of renal failure and mortality in diabetic patients, but the molecular mechanism of this process is not yet clear. The reduction of nuclear Erythroid2-related factor-2 (Nrf-2) and positive regulators of Nrf-2 proteins, such as DJ-1 and microRNA-126 (miR-126), after hypoxia and the promotion of reactive oxygen species, might be an intervention indicator in renal failure after myocardial ischemia-reperfusion. Therefore, this study evaluates the renoprotective effect of exercise training and Crataegus persica extract (CE) on myocardial ischemia-reperfusion-induced kidney injury in diabetic rats. Fifty rats were divided into five groups: healthy sedentary control (Con), sedentary diabetic (D), interval trained diabetic (TD), diabetic plus Crataegus persica extract treatment (CD), and interval trained diabetic plus Crataegus persica extract treatment (TCD) groups. The rats in the exercise groups were subjected to moderate-intensity interval training five days per week for ten weeks. The rats in CD and TCD groups received 300 mg/kg of Crataegus persica through gavage for ten weeks. Then, the subjects underwent 30 min of myocardial ischemia and subsequently reperfusion for 24 h. At the end of the experiment, insulin sensitivity, oxidative stress, renal function, histopathology of the kidney, Nrf-2, miR-126, and DJ-1 gene expression levels were evaluated. The results show that the treatments decreased elevated levels of renal oxidative stress, glomerular filtration rate, insulin sensitivity, and pathological score in diabetic rats. Also, the expression of Nrf-2 and miR-126, unlike DJ-1, decreased in diabetic rats due to interval training. Due to the results, diabetes aggravates acute myocardial ischemia-reperfusion-induced kidney injury, while moderate-intensity interval training and Crataegus persica treatment simultaneously ameliorate myocardial ischemia-reperfusion-induced renal injury via miR-126/Nrf-2 pathway and improve insulin sensitivity and renal function in type 1 diabetic rats.

JNK and Jag1/Notch2 co-regulate CXCL16 to facilitate cypermethrin-induced kidney damage

Cypermethrin (CYP), a widely-used composite pyrethroid pesticide, has underlying nephrotoxic effects. To elucidate potential roles of the MAPK pathway, the Jag/Notch pathway, and miRNAs in CYP-mediated kidney lesion, Sprague-Dawley rats and glomerular mesangial cells were used in this work. Results displayed that β-CYP abnormally altered renal histomorphology and ultrastructures, induced renal DNA damage, and impaired renal functions, as evidenced by the increase in plasma levels of Cys-C and β2-Mg. β-CYP activated the JNK/c-Jun pathway by inducing ROS and oxidative stress. Meanwhile, β-CYP changed the miRNA expression profile, miR-21-5p showing the most significant increase. Moreover, the Jag1/Notch2/Hes1 pathway was directly targeted by miR-21-5p, the mRNA and protein expression of Jag1, Notch2, and Hes1 being declined in vivo and in vitro. The chemokine CXCL16 was induced by β-CYP, accompanied by the inflammatory factor production and inflammatory cell infiltration in kidneys. The specific JNK inhibitor, Jag1 overexpression, Hes1 overexpression, bidirectional Co-IP, ChIP, and CXCL16 silencing demonstrated that CXCL16 co-regulated by the JNK/c-Jun and Jag1/Notch2/Hes1 pathways elicited renal inflammation. Collectively, our findings indicate that β-CYP is of nephrotoxicity and it not only directly changes renal histomorphology and ultrastructures, but induces CXCL16 to trigger renal inflammation via the JNK/c-Jun and Jag1/Notch2/Hes1 pathways, finally synergistically contributing to kidney damage.

DJ-1 affects oxidative stress and pyroptosis in hippocampal neurons of Alzheimer's disease mouse model by regulating the Nrf2 pathway

Studies have confirmed that DJ-1 is associated with diseases associated with the nervous system, including Alzheimer's disease (AD). However, the role of DJ-1 in the pathogenesis of AD has not been clarified. To investigate the effect of DJ-1 on brain tissue damage and cognitive function in AD mice and its possible mechanism, 5XFAD transgenic mice were used as AD model mice and DJ-1 in the brain was overexpressed by transfection of a lentiviral containing a specific targeting DJ-1 gene into the bilateral hippocampus of mice. Following lentivirus infection, the Morris water maze test was performed to assess the cognitive function of the mice. When the behavioral evaluation was completed, the brain tissue of the mouse was examined. Pathological changes were observed by hematoxylin-eosin staining. The levels of relevant indicators were analyzed by reverse transcription-quantitative PCR, ELISA and western blotting. Bilateral hippocampal injection of a lentivirus containing DJ-1 significantly increased the expression of DJ-1 in the hippocampus of 5XFAD transgenic mice. Overexpression of DJ-1 in the brain could ameliorate brain tissue damage, β-amyloid protein (Aβ) deposition and cognitive function in 5XFAD mice. Compared with the sham group, the reactive oxygen species activity and malondialdehyde content in the brain tissue of DJ-1 overexpressing 5XFAD mice were significantly decreased, while the superoxide dismutase activity was significantly increased (P<0.05). In addition, DJ-1 overexpression decreased the expression of caspase-1 and the levels of interleukin (IL) 1β and IL-18 in the hippocampus while ameliorating the death of hippocampal neurons in 5XFAD mice and without affecting the expression of caspase-3. Overexpression of DJ-1 resulted in a significant decrease in nuclear factor erythroid 2-related factor 2 (Nrf2) protein expression in the cytoplasmic while significantly increasing the expression of Nrf2 in the nucleus. Simultaneously, DJ-1 overexpression in the brain inhibited the activation of nanoparticles activate the NLR pyrin domain containing 3 inflammatory bodies in brain tissue. Overexpression of DJ-1 in the brain could repair brain tissue damage, Aβ deposition and cognitive function in 5XFAD mice, and its mechanism may be associated with an inhibition of oxidative stress and neuronal pyroptosis by regulating the Nrf2 signaling pathway.

SLC30A7 has anti-oxidant stress effects in high glucose-induced apoptosis via the NFE2L2/HMOX1 signal transduction pathway

AIMS

Apoptosis and oxidant stress are known to be involved in the pathogenesis of diabetic kidney disease (DKD). We have previously reported that zinc transporter 7 in SLC30 family (SLC30A7) inhibits apoptosis in rat peritoneal mesothelial cells under high glucose (HG) conditions. In the current study, we aimed to investigate whether SLC30A7 had effect for anti-oxidant stress in renal tubular epithelial cells under HG.

METHODS

SLC30A7 in HG-induced apoptosis in a normal rat kidney tubular epithelial cell line (NRK-52E cells)/kidneys of STZ-induced diabetic mice was examined and the activity of nuclear factor erythroid 2-related factor 2 (NFE2L2) was further analyzed by using real time RT-PCR, siRNA and Western blot protocols.

RESULTS

SLC30A7 was found to be up-regulated, while NFE2L2 was activated in kidneys of STZ-induced diabetic mice and HG-induced apoptosis of NRK-52E cells. Knock-down of SLC30A7 with siRNA protocol resulted in lower intracellular free zinc levels in the cells and decreased zinc distribution in the Golgi apparatus. Furthermore, knock-down of NFE2L2 down-regulated its target HMOX1 gene expression, decreased SLC30A7 activity but increased HG-induced apoptosis.

CONCLUSION

The current study provides new evidence that SLC30A7 has anti-oxidant stress effects in HG-induced apoptosis via the NFE2L2/HMOX1 signal transduction pathway.

ND-13, a DJ-1-Derived Peptide, Attenuates the Renal Expression of Fibrotic and Inflammatory Markers Associated with Unilateral Ureter Obstruction

DJ-1 is a redox-sensitive chaperone with reported antioxidant and anti-inflammatory properties in the kidney. The 20 amino acid (aa) peptide ND-13 consists of 13 highly conserved aas from the DJ-1 sequence and a TAT-derived 7 aa sequence that helps in cell penetration. This study aimed to determine if ND-13 treatment prevents the renal damage and inflammation associated with unilateral ureter obstruction (UUO). Male C57Bl/6 and DJ-1^-/- mice underwent UUO and were treated with ND-13 or vehicle for 14 days. ND-13 attenuated the renal expression of fibrotic markers TGF-β and collagen1a1 (Col1a1) and inflammatory markers TNF-α and IL-6 in C57Bl/6 mice. DJ-1^-/- mice treated with ND-13 presented similar decreased expression of TNF-α, IL-6 and TGF-β. However, in contrast to C57Bl/6 mice, ND-13 failed to prevent renal fibrosis or to ameliorate the expression of Col1a1 in this genotype. Further, UUO led to elevated urinary levels of the proximal tubular injury marker neutrophil gelatinase-associated lipocalin (NGAL) in DJ-1^-/- mice, which were blunted by ND-13. Our results suggest that ND-13 protects against UUO-induced renal injury, inflammation and fibrosis. These are all crucial mechanisms in the pathogenesis of kidney injury. Thus, ND-13 may be a new therapeutic approach to prevent renal diseases.

The Role of Transforming Growth Factor-Beta in Retinal Ganglion Cells with Hyperglycemia and Oxidative Stress

A characteristic of diabetes mellitus is hyperglycemia, which is considered with an emphasis on the diabetic retinopathy of progressive neurodegenerative disease. Retinal ganglion cells (RGCs) are believed to be important cells affected in the pathogenesis of diabetic retinopathy. Transforming growth factor-beta (TGF-β) is a neuroprotective protein that helps to withstand various neuronal injuries. To investigate the potential roles and regulatory mechanisms of TGF-β in hyperglycemia-triggered damage of RGCs in vitro, we established RGCs in 5.5, 25, 50, and 100 mM D-glucose supplemented media and focused on the TGF-β-related oxidative stress pathway in combination with hydrogen peroxide (H₂O₂). Functional experiments showed that TGF-β1/2 protein expression was upregulated in RGCs with hyperglycemia. The knockdown of TGF-β enhanced the accumulation of reactive oxygen species (ROS), inhibited the cell proliferation rate, and reduced glutathione content in hyperglycemia. Furthermore, the results showed that the TGF-β-mediated enhancement of antioxidant signaling was correlated with the activation of stress response proteins and the antioxidant pathway, such as aldehyde dehydrogenase 3A1 (ALDH3A1), heme oxygenase-1 (HO-1), nuclear factor erythroid 2-related factor (Nrf2), and hypoxia-inducible factor (HIF-1α). Summarizing, our results demonstrated that TGF-β keeps RGCs from hyperglycemia-triggered harm by promoting the activation of the antioxidant pathway, suggesting a potential anti-diabetic therapy for the treatment of diabetic retinopathy.

Protective role of NRF2 in macrovascular complications of diabetes

Macrovascular complications develop in over a half of the diabetic individuals, resulting in high morbidity and mortality. This poses a severe threat to public health and a heavy burden to social economy. It is therefore important to develop effective approaches to prevent or slow down the pathogenesis and progression of macrovascular complications of diabetes (MCD). Oxidative stress is a major contributor to MCD. Nuclear factor (erythroid‐derived 2)‐like 2 (NRF2) governs cellular antioxidant defence system by activating the transcription of various antioxidant genes, combating diabetes‐induced oxidative stress. Accumulating experimental evidence has demonstrated that NRF2 activation protects against MCD. Structural inhibition of Kelch‐like ECH‐associated protein 1 (KEAP1) is a canonical way to activate NRF2. More recently, novel approaches, such as activation of the Nfe2l2 gene transcription, decreasing KEAP1 protein level by microRNA‐induced degradation of Keap1 mRNA, prevention of proteasomal degradation of NRF2 protein and modulation of other upstream regulators of NRF2, have emerged in prevention of MCD. This review provides a brief introduction of the pathophysiology of MCD and the role of oxidative stress in the pathogenesis of MCD. By reviewing previous work on the activation of NRF2 in MCD, we summarize strategies to activate NRF2, providing clues for future intervention of MCD. Controversies over NRF2 activation and future perspectives are also provided in this review.

DJ-1 plays a neuroprotective role in SH-SY5Y cells by modulating Nrf2 signaling in response to lidocaine-mediated oxidative stress and apoptosis

To investigate the effects of DJ-1 on lidocaine-induced cytotoxicity in neurons and the link with Nrf2 signaling, SH-SY5Y cells were treated with 1, 4, 8, and 16 mM lidocaine. Cell viability was measured by MTT assay, and apoptosis was measured by flow cytometry analysis. The mitochondrial membrane potential, reactive oxygen species (ROS) levels, lipid peroxidation (MDA), and GSH/GSSG ratio were determined with specific kits. Expression of DJ-1, Nrf2, and Nrf2 downstream signaling proteins (glutathione peroxidase [GPx], heme oxygenase-1 [HO-1], catalase [CAT], and glutathione reductase [GR]), was determined by western blot and qRT-PCR. The cell viability was dramatically decreased, while levels of apoptosis, ROS and Cys106-oxidized DJ-1 were significantly enhanced following treatment with lidocaine (concentration 4-16 mM), and increases were observed in a dose-dependent manner. After treatment with 8 mM lidocaine, DJ-1, and nuclear Nrf2, as well as antioxidative stress-related proteins, GPx, GR, HO-1, and CAT, were all significantly inhibited. Overexpression of DJ-1 suppressed lidocaine-induced apoptosis and oxidative stress in SH-SY5Y cells and activated Nrf2 signalling at the same time, and these effects were reversed by the inhibition of Nrf2. DJ-1 could protect SH-SY5Y cells from lidocaine-induced apoptosis through inhibition of oxidative stress via Nrf2 signaling.

Effects of ATRA on diabetic rats with renal ischemia-reperfusion injury

Purpose

To explore the role of all-trans retinoic acid (ATRA) in renal ischemia/reperfusion injury of diabetic rats.

Methods

Sixty adult male rats were randomly divided into 6 groups, including sham group (S group), ischemia-reperfusion group (I/R group), ischemia-reperfusion+ATRA group (A group), diabetic group (D group), diabetic ischemia-reperfusion group (DI/R group), diabetic ischemia-reperfusion +ATRA group (DA group). The levels of creatinine (Cr), cystatin C (Cys-C) and β2-microglobulin (β2-MG) were measured. Morphology of renal tissue was observed under light microscope.

Results

DJ-1, Nrf2, HO-1 and caspase-3 were detected by western blot. DJ-1, Nrf2, HO-1 and caspase-3 in I/R group, D group and DI/R group was higher than that in S group. Compared with I/R group, Nrf2 and HO-1 in A group was decreased, but caspase-3 was increased. However, Nrf2 in DA group was higher than that in DI/R group, HO-1 and caspase-3 in DA group were lower than that in DI/R group. Compared with group S, Cr, Cys-C and β2-MG in I/R group, A group, D group, and DI/R group were higher. Whereas the levels of Cr, Cys-C, β2-MG and renal injury score in DA group were lower than those in DI/R group.

Conclusion

ATRA has a protective effect on renal ischemia-reperfusion injury in diabetic rats, maybe relating to DJ/Nrf2 pathway.

Bovine Herpesvirus 1 Productive Infection Led to Inactivation of Nrf2 Signaling through Diverse Approaches

Bovine herpesvirus type 1 (BoHV-1) is a significant cofactor for bovine respiratory disease complex (BRDC), the most important inflammatory disease in cattle. BoHV-1 infection in cell cultures induces overproduction of pathogenic reactive oxygen species (ROS) and the depletion of nuclear factor erythroid 2 p45-related factor 2 (Nrf2), a master transcriptional factor regulating a panel of antioxidant and cellular defense genes in response to oxidative stress. In this study, we reported that the virus productive infection in MDBK cells at the later stage significantly decreased the expression levels of heme oxygenase-1 (HO-1) and NAD(P)H quinone oxidoreductase-1 (NQO1) proteins, the canonical downstream targets regulated by Nrf2, inhibited Nrf2 acetylation, reduced the accumulation of Nrf2 proteins in the nucleus, and relocalized nuclear Nrf2 proteins to form dot-like staining patterns in confocal microscope assay. The differential expression of Kelch-like ECH associated protein 1 (KEAP1) and DJ-1 proteins as well as the decreased association between KEAP1 and DJ-1 promoted Nrf2 degradation through the ubiquitin proteasome pathway. These data indicated that the BoHV-1 infection may significantly suppress the Nrf2 signaling pathway. Moreover, we found that there was an association between Nrf2 and LaminA/C, H3K9ac, and H3K18ac, and the binding ratios were altered following the virus infection. Taken together, for the first time, we provided evidence showing that BoHV-1 infection inhibited the Nrf2 signaling pathway by complicated mechanisms including promoting Nrf2 degradation, relocalization of nuclear Nrf2, and inhibition of Nrf2 acetylation.

Apigenin Protects Against Renal Tubular Epithelial Cell Injury and Oxidative Stress by High Glucose via Regulation of NF-E2-Related Factor 2 (Nrf2) Pathway

Background

Diabetic nephropathy (DN) is a disease characterized by oxidative stress and apoptosis of renal tubular epithelial cells driven by hyperglycemia. Apigenin is a flavonoid compound that possesses potent anti-apoptotic properties. The present study aimed to explore the protective effects and underlying mechanisms of apigenin on renal tubular epithelial cells exposed to hyperglycemia.

Material/Methods

Human renal epithelial cell HK-2 were incubated to D-glucose to establish in vitro DN model. The cell viability, lactate dehydrogenase (LDH) release, apoptosis and oxidative stress were evaluated. qRT-PCR was performed to determine the mRNA levels of NF-E2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1). Western blot analysis was performed to measure the protein expressions of Nrf2.

Results

In HK-2 cells, high glucose reduced cell viability in a concentration- and time-dependent manner. Apigenin suppressed the decrease in cell viability and increase in supernatant LDH release at 100 and 200 μM after 48-h treatment. Apigenin reduced apoptotic rate and pro-inflammatory cytokines production. Apigenin suppressed oxidative stress and increased mRNA expressions of Nrf2 and HO-1. Inhibition of Nrf2 using small interfering RNA (siRNA), or cotreatment with LY294002, an inhibitor of PI3K/Akt, abolished the protective effect on high glucose-induced injury, oxidative stress, and pro-inflammatory cytokines production by apigenin. LY294002 also attenuated the increase in Nrf2 protein by apigenin in high glucose-treated HK-2 cells.

Conclusions

Apigenin protects renal tubular epithelial cells against high glucose-induced injury through suppression of oxidative stress and inflammation via activation of the Nrf2 pathway.

Elevated levels of 8-OHdG and PARK7/DJ-1 in peri-implantitis mucosa

BACKGROUND

Reactive oxygen species contribute to periodontal tissue homeostasis under control of anti-oxidative responses. Disruption in this balance induces severe inflammation and extended tissue degradation.

PURPOSE

Aim of this study was to identify the expression levels of nuclear factor, erythroid 2 like 2 (NFE2L2/NRF2), Parkinsonism associated deglycase (PARK7/DJ-1), kelch-like ECH associated protein 1 (KEAP1), and 8-hydroxy-deoxyguanosine (8-OHdG) in peri-implant mucosal tissues affected by peri-implantitis, and to compare the levels to those of periodontally diseased and healthy tissue samples.

METHODS

Tissue biopsies were collected from systemically healthy, non-smoking 12 peri-implantitis patients, 13 periodontitis patients, and 13 periodontally healthy controls. Expression levels of NFE2L2/NRF2, PARK7/DJ-1, KEAP1, and 8-OHdG in tissue samples were analyzed immunohistochemically. Statistical analysis was performed by one-way ANOVA with Tukey's HSD test.

RESULTS

Inflammatory cell infiltration in the connective tissue and loss of architecture in the spinous layer of the epithelium were prominent in peri-implantitis. Proportions of 8-OHdG and PARK7/DJ-1 expressing cells were elevated in both peri-implantitis (P = .025 for 8-OHdG and P = .014 for PARK7/DJ-1) and periodontitis (P = .038 for 8-OHdG and P = .012 for PARK7/DJ-1) groups in comparison with controls. Staining intensities of 8-OHdG and PARK7/DJ-1 were higher in the periodontitis and peri-implantitis groups than in the control (P < .01) groups. There was no difference in the expression levels of NFE2L2/NRF2 between the groups. KEAP1 was not observed in any tissue sample.

CONCLUSIONS

Peri-implantitis is characterized by severe inflammation and architectural changes in the epithelium and connective tissue. The expressions of 8-OHdG and PARK7/DJ-1 are elevated in both peri-implantitis and periodontitis.

Mechanism of myocardial ischemia/reperfusion-induced acute kidney injury through DJ-1/Nrf2 pathway in diabetic rats

The objective of the present study was to investigate acute kidney injury (AKI) induced by myocardial ischemia/reperfusion (MIR) in diabetic rats and elucidate its underlying mechanism. A rat model of MIR was established by left anterior descending coronary artery occlusion for 30 min, followed by reperfusion for 2 h. Rats were randomly divided into four groups: i) Sham group, ii) sham + MIR group, iii) diabetic group and iv) diabetes + MIR group. Myocardial injury was detected by plasma creatine kinase isoenzyme MB and lactate dehydrogenase assays. AKI induced by MIR in diabetic rats was characterized by increases in cystatin C and β2-microglobulin levels. Oxidative stress injury was accompanied by an increase of malondialdehyde levels and a decrease of total antioxidative capacity in the renal tissues. Immunohistochemistry and western blot analysis demonstrated that the expression of DJ-1 and nuclear factor erythroid 2-related factor 2 (Nrf2) were significantly increased in the diabetes + MIR group compared with that in the sham + MIR and diabetic groups. Taken together, these results suggested that AKI induced by MIR in diabetic rats may be associated with activation of the DJ-1/Nrf2 pathway.

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.

Value of the combined examination of Cys-C and HbA1c for diagnosis of early renal injury in pediatric diabetes

The objective of the present study was to evaluate the combined application of measuring cystatin C (Cys-C) and hemoglobin A1c (HbA1c) levels for early renal injury in pediatric patients with type 2 diabetes. A total of 130 children with type 2 diabetes admitted to our hospital from May 2013 to July 2015 were selected. Patients were divided according to whether there was complication of renal injury. In group A (n=65), the patients had renal injury and in group B (n=65), the patients did not have renal injury. The levels of Cys-C and HbA1c in the two groups were examined. The results showed that the levels of Cys-C and HbA1c of patients in group A were significantly higher than those in group B (P<0.05), and the positive rate of the combined examination of Cys-C and HbA1c in group A was 92.3%, and was higher than that of the individual examinations of either Cys-C or HbA1c (P<0.05). The Spearman's correlation coefficient analysis was applied to group B and showed that Cys-C was positively correlated with HbA1c (r=0.842, P<0.05). From analysis of the receiver operating characteristic curves, the combined examination of Cys-C and HbA1c surpassed the individual examinations of Cys-C or HbA1c in sensitivity and specificity (P<0.05). In conclusion, the positive detection rate of early renal injury was significantly increased by the combined examination of Cys-C and HbA1c in pediatric patients with type 2 diabetes, which is beneficial for early identification and diagnosis of this diseases and is worthy of clinical application.

Overexpression of DJ-1 reduces oxidative stress and attenuates hypoxia/reoxygenation injury in NRK-52E cells exposed to high glucose

Patients with diabetes are more vulnerable to renal ischemia/reperfusion (I/R) injury, which is implicated in hyperglycemia-induced oxidative stress. We previously reported that the hyperglycemia-induced inhibition of DJ-1, a novel oncogene that exhibits potent antioxidant activity, is implicated in the severity of myocardial I/R injury. In the present study, we aimed to explore the role of DJ-1 in hypoxia/reoxygenation (H/R) injury in renal cells exposed to high glucose (HG). For this purpose, NRK-52E cells were exposed to HG (30 mM) for 48 h and then exposed to hypoxia for 4 h and reoxygenation for 2 h, which significantly decreased cell viability and superoxide dismutase (SOD) activity, and increased the malondialdehyde (MDA) content, accompanied by a decrease in DJ-1 protein expression. The overexpression of DJ-1 by transfection with a DJ-1 overexpression plasmid exerted protective effects against HG-induced H/R injury, as evidenced by increased CCK-8 levels and SOD activity, the decreased release of lactate dehydrogenase (LDH) and the decreased MDA content, and increased nuclear factor (erythroid-derived 2)-like 2 (Nrf2) and heme oxygenase-1 (HO-1) expression. Similar effects were observed following treatment with the antioxidant, N-acetylcysteine. These results suggest that the overexpression of DJ-1 reduces oxidative stress and attenuates H/R injury in NRK-52E cells exposed to HG.

Cyclocarya paliurus extract alleviates diabetic nephropathy by inhibiting oxidative stress and aldose reductase

Diabetes is the leading cause of end-stage renal disease because diabetic nephropathy (DN) develops in 30-40% of the patients. This study investigated the protective effect of the aqueous extract from leaves of Cyclocarya paliurus (Batal.) Iljinsk (ACP) on DN by inhibiting oxidative stress and aldose reductase (AR) activity. ACP was obtained by hot water extraction. The in vitro antioxidant capability and AR inhibition of ACP were investigated by employing various established systems. DN rats were used to assess the reno-protective effect of ACP. Results showed that the polysaccharide and total polyphenol contents of ACP were (479.3 ± 19.8) mg/g and (38.3 ± 2.3) mg/g, respectively. ACP exhibited strong antioxidant ability and AR inhibition in vitro and in vivo; furthermore, the inhibition mechanism of ACP in AR takes the form of uncompetitive inhibition. In addition, the animals treated with ACP showed significant amelioration of blood glucose, serum biomarkers related to renal function, urinary protein excretion, and histopathological changes in the kidney. The results suggest that ACP has a potential role in ameliorating renal damage involved in DN.

Protein DJ-1 and its anti-oxidative stress function play an important role in renal cell mediated response to profibrotic agents

In the pathogenesis of renal fibrosis, oxidative stress (OS) enhances the production of reactive oxygen species (ROS) leading to sustained cell growth, inflammation, excessive tissue remodelling and accumulation, which results in the development and acceleration of renal damage.