Extracellular superoxide dismutase in biology and medicine

Effect of Tauroursodeoxycholic Acid and 4-Phenylbutyric Acid on Metabolism of Copper and Zinc in Type 1 Diabetic Mice Model

Alternations of copper (Cu) and zinc (Zn) status in diabetes have received a great attention. Tauroursodeoxycholic acid (TUDCA) and 4-phenylbutyric acid (PBA) could alleviate the increased endoplasmic reticulum (ER) stress and prevent insulin resistance. This study aimed to investigate the effect of TUDCA and PBA on metabolism of Cu and Zn in diabetic mice model. Diabetes was induced by streptozotocin in FVB mice treated with and without TUDCA and PBA. Determination of Cu and Zn in tissues and serum by acid digestion was followed by ICP-MS. The renal and serum Cu levels were significantly higher, while the hepatic Cu and Zn levels were significantly decreased in the diabetic mice at 2 weeks and 2 months after diabetes onset. The increase of cardiac Cu together with the decrease of muscular Zn was found in the diabetic mice only at 2 months. Cu levels were positively correlated with Zn in the heart, liver, kidney, muscle, spleen, and serum of diabetic and control mice at both 2 weeks and 2 months. Both PBA and TUDCA reduced serum Zn, and PBA reduced hepatic Cu to normal levels in the diabetic mice at two time points, while PBA normalized serum Cu in the diabetic mice only at 2 months. PBA increased hepatic Zn to normal levels in the diabetic mice at 2 weeks, while it partially increased hepatic Zn in the same group at 2 months. Therefore, maintaining homeostasis of Cu and Zn by TUDCA and PBA in diabetes needs to be received with special attention.

The Sequence Characteristics and Expression Models Reveal Superoxide Dismutase Involved in Cold Response and Fruiting Body Development in Volvariella volvacea

As the first defence for cells to counteract the toxicity of active oxygen, superoxide dismutase (SOD) plays an important role in the response of living organisms to stress and cell differentiation. One extracellular Cu-ZnSOD (ecCu-ZnSOD), and two MnSODs, were identified based on the Volvariella volvacea genome sequence. All three genes have complicated alternative splicing modes during transcription; only when the fourth intron is retained can the Vv_Cu-Znsod1 gene be translated into a protein sequence with SOD functional domains. The expression levels of the three sod genes in the pilei are higher than in the stipe. The Vv_Cu-Znsod1 and the Vv_Mnsod2 are co-expressed in different developmental stages of the fruiting body, with the highest level of expression in the pilei of the egg stage, and they show a significant, positive correlation with the efficiency of karyogamy, indicating the potential role of these two genes during karyogamy. The expression of the ecCu-Znsod and two Vv_Mnsod genes showed a significant up-regulated when treated by cold stress for one hour; however, the lack of the intracellular Cu-ZnSOD encoding gene (icCu-Znsod) and the special locus of the ecCu-Znsod gene initiation codon suggested a possible reason for the autolysis phenomenon of V. volvacea in cold conditions.

Evidence of the gastroprotective and anti- Helicobacter pylori activities of β-mangostin isolated from Cratoxylum arborescens (vahl) blume

Purpose

β-Mangostin (BM) from Cratoxylum arborescens demonstrated various pharmacological activities such as anticancer and anti-inflammatory. In this study, we aimed to investigate its antiulcer activity against ethanol ulcer model in rats.

Materials and methods

BM was isolated from C. arborescens. Gastric acid output, ulcer index, gross evaluation, mucus production, histological evaluation using hematoxylin and eosin and periodic acid–Schiff staining and immunohistochemical localization for heat shock protein 70 (HSP70) and Bax proteins were investigated. Possible involvement of reduced glutathione, lipid peroxidation, prostaglandin E2, antioxidant enzymes, superoxide dismutase and catalase enzymes, radical scavenging, nonprotein sulfhydryl compounds, and anti-Helicobacter pylori were investigated.

Results

BM showed antisecretory activity against the pylorus ligature model. The pretreatment with BM protect gastric mucosa from ethanol damaging effect as seen by the improved gross and histological appearance. BM significantly reduced the ulcer area formation, the submucosal edema, and the leukocytes infiltration compared to the ulcer control. The compound showed intense periodic acid–Schiff staining to the gastric mucus layer and marked amount of alcian blue binding to free gastric mucus. BM significantly increased the gastric homogenate content of prostaglandin E2 glutathione, superoxide dismutase, catalase, and nonprotein sulfhydryl compounds. The compound inhibited the lipid peroxidation revealed by the reduced gastric content of malondialdehyde. Moreover, BM upregulate HSP70 expression and downregulate Bax expression. Furthermore, the compound showed interesting anti-H. pylori activity.

Conclusion

Thus, it could be concluded that BM possesses gastroprotective activity, which could be attributed to the antisecretory, mucus production, antioxidant, HSP70, antiapoptotic, and anti-H. pylori mechanisms.

ROS/oxidative stress signaling in osteoarthritis

Osteoarthritis is the most common joint disorder with increasing prevalence due to aging of the population. Its multi-factorial etiology includes oxidative stress and the overproduction of reactive oxygen species, which regulate intracellular signaling processes, chondrocyte senescence and apoptosis, extracellular matrix synthesis and degradation along with synovial inflammation and dysfunction of the subchondral bone. As disease-modifying drugs for osteoarthritis are rare, targeting the complex oxidative stress signaling pathways would offer a valuable perspective for exploration of potential therapeutic strategies in the treatment of this devastating disease.

Toward understanding the impacts of sediment contamination on a native fish species: transcriptional effects, EROD activity, and biliary PAH metabolites

BACKGROUND

Both frequency and intensity of flood events are expected to increase as a result of global climate change in the upcoming decades, potentially resulting in increased re-suspension of sediments in fluvial systems. Contamination of these re-suspended sediments with legacy contaminants, including dioxins and dioxin-like compounds (DLCs), as well as polycyclic aromatic hydrocarbons (PAHs) is of great ecotoxicological concern. DLCs, and to some extent also PAHs, exhibit their toxicity through activation of the aryl hydrocarbon receptor (AhR). However, interactions of DLCs with pathways other than those known to be mediated through the AhR are not fully understood to date.

METHODS

This study aimed to investigate molecular and biochemical effects in roach (Rutilus rutilus) during a 10 days exposure to suspensions of three natural sediments that differed in the level of DLC contamination. Concentrations of biliary PAH metabolites and hepatic 7-ethoxyresorufin-O-deethylase activity were quantified in exposed fish. Furthermore, the abundance of transcripts of several genes related to energy metabolism, response to oxidative stress, and apoptosis, as well as cytochrome P450 1A (cyp1a) was quantified.

RESULTS

Biliary PAH metabolites and activation of the AhR were confirmed as suitable early warning biomarkers of exposure to suspended sediments containing DLCs and PAHs that corresponded well with analytically determined concentrations of those contaminants. Although the abundances of transcripts of superoxide dismutase (sod), protein kinase c delta (pkcd), and ATP-binding cassette transporter c9 (abcc9) were altered by the treatment compared with unexposed control fish, none of these showed a time- or concentration-dependent response. The abundance of transcripts of pyruvate carboxylase (pc) and transferrin variant d (tfd) remained unaltered by the treatments.

CONCLUSIONS

We have shown that contaminated sediments can become a risk for fish during re-suspension events (e.g., flooding and dredging). We have also demonstrated that roach, which are native to most European freshwater systems, are suitable sentinel species due to their great sensitivity and ecological relevance. Roach may be particularly suitable in future field studies to assess the toxicological concerns associated with the release of DLCs and PAHs during sediment re-suspension.

The Extracellular Matrix in Bronchopulmonary Dysplasia: Target and Source

Bronchopulmonary dysplasia (BPD) is a common complication of preterm birth that contributes significantly to morbidity and mortality in neonatal intensive care units. BPD results from life-saving interventions, such as mechanical ventilation and oxygen supplementation used to manage preterm infants with acute respiratory failure, which may be complicated by pulmonary infection. The pathogenic pathways driving BPD are not well-delineated but include disturbances to the coordinated action of gene expression, cell-cell communication, physical forces, and cell interactions with the extracellular matrix (ECM), which together guide normal lung development. Efforts to further delineate these pathways have been assisted by the use of animal models of BPD, which rely on infection, injurious mechanical ventilation, or oxygen supplementation, where histopathological features of BPD can be mimicked. Notable among these are perturbations to ECM structures, namely, the organization of the elastin and collagen networks in the developing lung. Dysregulated collagen deposition and disturbed elastin fiber organization are pathological hallmarks of clinical and experimental BPD. Strides have been made in understanding the disturbances to ECM production in the developing lung, but much still remains to be discovered about how ECM maturation and turnover are dysregulated in aberrantly developing lungs. This review aims to inform the reader about the state-of-the-art concerning the ECM in BPD, to highlight the gaps in our knowledge and current controversies, and to suggest directions for future work in this exciting and complex area of lung development (patho)biology.

Biochemical assessment of oxidative status versus liver enzymes in patients with chronic fascioliasis

The aim of this study was to examine the oxidative status in Egyptian patients suffering chronic fascioliasis. The relationship between serum malondialdehyde (MDA) levels, superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPX) activities was investigated in relation to the level of liver enzymes; ALT and AST compared to healthy controls. Twenty patients versus ten controls were included in the study. Among cases the MDA, CAT, AST and ALT were higher than controls, while SOD and GPX higher values were present among controls. There was a highly significant difference between cases and controls as regard MDA, CAT, SOD, GPX, and AST, and a significant difference regarding ALT. The findings of increased serum lipid peroxidation and decreased antioxidant enzymes in erythrocytes of chronic fascioliasis patients indicated the presence of persistent inflammation and oxidative stress which confirms the underlying pathogenesis and reflected the stage of infection providing a baseline data for comparison between normal and infected patients guided by the level of liver enzymes in relation to oxidative status.

Exendin-4 promotes extracellular-superoxide dismutase expression in A549 cells through DNA demethylation

Exendin-4 is an agonist of the glucagon-like peptide 1 receptor (GLP-1R) and is used in the treatment of type 2 diabetes. Since human GLP-1R has been identified in various cells besides pancreatic cells, exendin-4 is expected to exert extrapancreatic actions. It has also been suggested to affect gene expression through epigenetic regulation, such as DNA methylation and/or histone modifications. Furthermore, the expression of extracellular-superoxide dismutase (EC-SOD), a major SOD isozyme that is crucially involved in redox homeostasis, is regulated by epigenetic factors. In the present study, we demonstrated that exendin-4 induced the demethylation of DNA in A549 cells, which, in turn, affected the expression of EC-SOD. Our results showed that the treatment with exendin-4 up-regulated the expression of EC-SOD through GLP-1R and demethylated some methyl-CpG sites (methylated cytosine at 5'-CG-3') in the EC-SOD gene. Moreover, the treatment with exendin-4 inactivated DNA methyltransferases (DNMTs), but did not change their expression levels. In conclusion, the results of the present study demonstrated for the first time that exendin-4 regulated the expression of EC-SOD by reducing the activity of DNMTs and demethylation of DNA within the EC-SOD promoter region in A549 cells.

Protective effects of quercetin glycosides, rutin, and isoquercetrin against 6-hydroxydopamine (6-OHDA)-induced neurotoxicity in rat pheochromocytoma (PC-12) cells

There is increasing evidence that free radicals induced oxidative stress is a major causative agent in the pathogenesis of neurodegenerative diseases, particularly Parkinson's disease. Quercetin glycosides, namely rutin and isoquercitrin, are flavonoid polyphenol compounds found ubiquitously in fruits and vegetables and have been known to possess antioxidant effects. This study was designed to compare the neuroprotective effects of quercetin glycosides rutin and isoquercitrin in 6-OHDA-induced rat pheochromocytoma (PC-12) cells. The results showed that both rutin and isoquercitrin significantly increased antioxidant enzymes, catalase, superoxide dismutase, glutathione peroxidase, and glutathione level that were attenuated by 6-OHDA in PC-12 cells. There was no significant difference in the activation of glutathione and glutathione peroxidase enzymes between rutin and isoquercitrin. These two glycosides were equally effective in suppressing lipid peroxidation in 6-OHDA-induced PC-12 cells as both compounds suppressed the malondialdehyde generation and prevented cell damage. In conclusion, quercetin glycosides rutin and isoquercetrin are having a significant neuroprotective effect against 6-OHDA toxicity in PC-12 cells.

Angiotensin II-superoxide-NFκB signaling and aortic baroreceptor dysfunction in chronic heart failure

Chronic heart failure (CHF) affects approximately 5.7 million people in the United States. Increasing evidence from both clinical and experimental studies indicates that the sensitivity of arterial baroreflex is blunted in the CHF state, which is a predictive risk factor for sudden cardiac death. Normally, the arterial baroreflex regulates blood pressure and heart rate through sensing mechanical alteration of arterial vascular walls by baroreceptor terminals in the aortic arch and carotid sinus. There are aortic baroreceptor neurons in the nodose ganglion (NG), which serve as the main afferent component of the arterial baroreflex. Functional changes of baroreceptor neurons are involved in the arterial baroreflex dysfunction in CHF. In the CHF state, circulating angiotensin II (Ang II) and local Ang II concentration in the NG are elevated, and AT1R mRNA and protein are overexpressed in the NG. Additionally, Ang II-superoxide-NFκB signaling pathway regulates the neuronal excitability of aortic baroreceptors through influencing the expression and activation of Na_v channels in aortic baroreceptors, and subsequently causes the impairment of the arterial baroreflex in CHF. These new findings provide a basis for potential pharmacological interventions for the improvement of the arterial baroreflex sensitivity in the CHF state. This review summarizes the mechanisms responsible for the arterial baroreflex dysfunction in CHF.

Anti-oxidative and anti-apoptosis effects of egg white peptide, Trp-Asn-Trp-Ala-Asp, against H2O2-induced oxidative stress in human embryonic kidney 293 cells

Peptides derived from egg white protein are well-known for their abundant species and biological properties. The aim of this study was to investigate the anti-oxidative and anti-apoptosis effects of (Trp-Asn-Trp-Ala-Asp) WNWAD, a pentapeptide derived from egg white ovomucin pepsin hydrolysates, against the oxidative stress induced by H2O2 in HEK-293 cells. Oxygen radical absorbance capacity (ORAC) results showed that WNWAD possessed extraordinary oxygen radical absorption capacity (with an ORAC value = 2.91 μM TE μM(-1)) in vitro. Then, at the cellular level, MTS assay results displayed that WNWAD dose-dependently inhibited H2O2-induced cellular oxidative stress in HEK-293 cells and fully recovered the oxidative damage induced by 400 μM H2O2 at a concentration of 1 μM. The 2',7'-dichlorofluorescein diacetate (DCFH-DA) fluorescent probe assay further proved that WNWAD inhibited cellular oxidative stress by reducing intracellular ROS accumulation in intact HEK-293 cells. In addition, scanning electron microscopy (SEM) images showed that the morphology of HEK-293 cells under H2O2 treatment displayed a cell apoptosis phenotype, while WNWAD pretreatment prevented the development of this phenotype. Furthermore, Western blot results indicated that WNWAD up-regulated the level of the anti-apoptotic protein Bcl-2 and down-regulated the levels of apoptosis executor proteins, cleaved caspase-3 and cleaved PRAP, in H2O2-induced oxidative stress in HEK-293 cells. All the above results suggested that WNWAD protected HEK-293 cells against H2O2-induced oxidative stress by inhibiting intracellular ROS accumulation and blocking the ROS activated mitochondria-mediated cell apoptosis pathway.

The protective effect of astragaloside IV against benzo[a]pyrene induced endothelial progenitor cell dysfunction

AIMS

Benzo[a]pyrene (BaP), a prominent component of tobacco, has been revealed to induce damage to endothelial progenitor cells (EPCs). Astragaloside IV (AS-IV) is widely used for the treatment of cardiovascular diseases in China. In this study, we evaluated the effects of AS-IV on the function of human EPCs after BaP exposure and explored the underlying mechanism.

MATERIALS AND METHODS

Human umbilical cord blood mononuclear cells were isolated using density gradient centrifugation. Cells of the 4th passage were randomly divided into 6 groups. EPCs of experimental groups were pre-treated with different concentrations (2, 10 and 50 μg/mL) of AS-IV for 2h before exposure to BaP (20 μM) for 24h. The proliferation, migration, and adhesion of the treated EPCs were evaluated using a cell counting kit-8, Transwell assay and adhesion assay respectively. Interleukin-1β, tumor necrosis factor-α, malondialdehyde and SOD contents in the supernatant were evaluated. The expression of RAGE protein was measured by Western blotting.

KEY FINDINGS

The results demonstrated that AS-IV pre-treatment significantly improved BaP-induced dysfunction of EPCs in terms of proliferation, migration and adhesion. Furthermore, AS-IV reduced the production of reactive oxygen species, malondialdehyde, interleukin-1β and tumor necrosis factor-α of the BaP-treated EPCs. Finally AS-IV pre-treated EPCs showed an increased SOD activity and decreased RAGE protein expression.

SIGNIFICANCE

AS-IV is able to prevent BaP-mediated EPC dysfunction by at least inhibiting oxidative stress through the RAGE pathway.

Identification and characterization of two phospholipid hydroperoxide glutathione peroxidase genes from the Mediterranean species of the whitefly Bemisia tabaci complex

Phospholipid hydroperoxide glutathione peroxidases (PHGPXs) are essential enzymes of the cellular antioxidant defense system during insect-plant interactions. However, little attention has been devoted to the functional characterization of PHGXPs in the whitefly Bemisia tabaci. Here, we report the identification and characterization of two PHGPX genes, designated as BtQ-PHGPX1 and BtQ-PHGPX2 from the Mediterranean species of the B. tabaci complex. Sequence analysis indicated that the length of BtQ-PHGPX1 is of 942 bp with a 729 bp open-reading frame (ORF) encoding 242 amino acids, and BtQ-PHGPX2 is of 699 bp with a 567 bp ORF encoding 188 amino acids. Sequence alignment analysis showed that BtQ-PHGPX1 and BtQ-PHGPX2 shared high similarity with other known PHGPXs. The NVASXCGXT, FPCNQFXXQEPG, and IKWNFXKFLV surrounded the reactive cysteine, glutamine, and tryptophan residues, respectively. Recombinant BtQ-PHGPX1 and BtQ-PHGPX2 were overexpressed in Escherichia coli and purified. quantitative reverse transcription-polymerase chain reaction (qRT-PCR) analysis with whiteflies of different development stages showed that the mRNA levels of BtQ-PHGPX2 were significantly higher in larvae than in other stages. The mRNA levels of BtQ-PHGPX2 were significantly higher than BtQ-PHGPX1 during all the developmental stages. The mRNA levels of BtQ-PHGPX1 and BtQ-PHGPX2 in female adults were relatively higher than in male adults. The expression of BtQ-PHGPX1 and BtQ-PHGPX2 was induced by the insecticide imidacloprid. These results suggest that BtQ-PHGPX1 and BtQ-PHGPX2 may participate in detoxification of oxidative hazards in B. tabaci.

Biological Activities of Reactive Oxygen and Nitrogen Species: Oxidative Stress versus Signal Transduction

In the past, reactive oxygen and nitrogen species (RONS) were shown to cause oxidative damage to biomolecules, contributing to the development of a variety of diseases. However, recent evidence has suggested that intracellular RONS are an important component of intracellular signaling cascades. The aim of this review was to consolidate old and new ideas on the chemical, physiological and pathological role of RONS for a better understanding of their properties and specific activities. Critical consideration of the literature reveals that deleterious effects do not appear if only one primary species (superoxide radical, nitric oxide) is present in a biological system, even at high concentrations. The prerequisite of deleterious effects is the formation of highly reactive secondary species (hydroxyl radical, peroxynitrite), emerging exclusively upon reaction with another primary species or a transition metal. The secondary species are toxic, not well controlled, causing irreversible damage to all classes of biomolecules. In contrast, primary RONS are well controlled (superoxide dismutase, catalase), and their reactions with biomolecules are reversible, making them ideal for physiological/pathophysiological intracellular signaling. We assume that whether RONS have a signal transducing or damaging effect is primarily defined by their quality, being primary or secondary RONS, and only secondly by their quantity.

Mechanisms of Heightened Airway Sensitivity and Responses to Inhaled SO2 in Asthmatics

Sulfur dioxide (SO2) is a problematic inhalable air pollutant in areas of widespread industrialization, not only in the United States but also in countries undergoing rapid industrialization, such as China, and it can be a potential trigger factor for asthma exacerbations. It is known that asthmatics are sensitive to the effects of SO2; however, the basis of this enhanced sensitivity remains incompletely understood. A PubMed search was performed over the course of 2014, encompassing the following terms: asthma, airway inflammation, sulfur dioxide, IL-10, mouse studies, and human studies. This search indicated that biomarkers of SO2 exposure, SO2 effects on airway epithelial cell function, and animal model data are useful in our understanding of the body's response to SO2, as are SO2-associated amplification of allergic inflammation, and potential promotion of neurogenic inflammation due to chemical irritant properties. While definitive answers are still being sought, these areas comprise important foci of consideration regarding asthmatic responses to inhaled SO2. Furthermore, IL-10 deficiency associated with asthma may be another important factor associated with an inability to resolve inflammation and mitigate oxidative stress resulting from SO2 inhalation, supporting the idea that asthmatics are predisposed to SO2 sensitivity, leading to asthma exacerbations and airway dysfunction.

α-Synuclein, a chemoattractant, directs microglial migration via H2O2-dependent Lyn phosphorylation

Malformed α-Synuclein (α-syn) aggregates in neurons are released into the extracellular space, activating microglia to induce chronic neuroinflammation that further enhances neuronal damage in α-synucleinopathies, such as Parkinson's disease. The mechanisms by which α-syn aggregates activate and recruit microglia remain unclear, however. Here we show that α-syn aggregates act as chemoattractants to direct microglia toward damaged neurons. In addition, we describe a mechanism underlying this directional migration of microglia. Specifically, chemotaxis occurs when α-syn binds to integrin CD11b, leading to H2O2 production by NADPH oxidase. H2O2 directly attracts microglia via a process in which extracellularly generated H2O2 diffuses into the cytoplasm and tyrosine protein kinase Lyn, phosphorylates the F-actin-associated protein cortactin after sensing changes in the microglial intracellular concentration of H2O2. Finally, phosphorylated cortactin mediates actin cytoskeleton rearrangement and facilitates directional cell migration. These findings have significant implications, given that α-syn-mediated microglial migration reaches beyond Parkinson's disease.

Nicorandil prevents sirolimus-induced production of reactive oxygen species, endothelial dysfunction, and thrombus formation

Sirolimus (SRL) is widely used to prevent restenosis after percutaneous coronary intervention. However, its beneficial effect is hampered by complications of thrombosis. Several studies imply that reactive oxygen species (ROS) play a critical role in endothelial dysfunction and thrombus formation. The present study investigated the protective effect of nicorandil (NIC), an anti-angina agent, on SRL-associated thrombosis. In human coronary artery endothelial cells (HCAECs), SRL stimulated ROS production, which was prevented by co-treatment with NIC. The preventive effect of NIC on ROS was abolished by 5-hydroxydecanoate but not by 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one. NIC also inhibited SRL-induced up-regulation of NADPH oxidase subunit p22(phox) mRNA. Co-treatment with NIC and SRL significantly up-regulated superoxide dismutase 2. NIC treatment significantly improved SRL-induced decrease in viability of HCAECs. The functional relevance of the preventive effects of NIC on SRL-induced ROS production and impairment of endothelial viability was investigated in a mouse model of thrombosis. Pretreatment with NIC inhibited the SRL-induced acceleration of FeCl3-initiated thrombus formation and ROS production in the testicular arteries of mice. In conclusion, NIC prevented SRL-induced thrombus formation, presumably due to the reduction of ROS and to endothelial protection. The therapeutic efficacy of NIC could represent an additional option in the prevention of SRL-related thrombosis.

Extracellular Superoxide Dismutase Protects against Proteinuric Kidney Disease

Extracellular superoxide dismutase (EC-SOD), also known as SOD3, is an antioxidant expressed at high levels in normal adult kidneys. Because oxidative stress contributes to a variety of kidney injuries, we hypothesized that EC-SOD may be protective in CKD progression. To study this hypothesis, we used a murine model of ADR nephropathy characterized by albuminuria and renal dysfunction. We found that levels of EC-SOD diminished throughout the course of disease progression and were associated with increased levels of NADPH oxidase and oxidative stress markers. EC-SOD null mice were sensitized to ADR injury, as evidenced by increases in albuminuria, serum creatinine, histologic damage, and oxidative stress. The absence of EC-SOD led to increased levels of NADPH oxidase and an increase in β-catenin signaling, which has been shown to be pathologic in a variety of kidney injuries. Exposure of EC-SOD null mice to either chronic angiotensin II infusion or to daily albumin injections also caused increased proteinuria. In contrast, EC-SOD null mice subjected to nonproteinuric CKD induced by unilateral ureteral obstruction exhibited no differences compared with wild-type mice. Finally, we also found a decrease in EC-SOD in human CKD biopsy samples, similar to our findings in mice. Therefore, we conclude that EC-SOD is protective in CKDs characterized by proteinuria.

Antioxidative status and oxidative stress in the fetal circulation at birth: the effects of time of delivery and presence of labor

BACKGROUND

There are important physiological changes in the maternal, placental, and fetal compartments during pregnancy and labor. Increased oxidative stress has been demonstrated during labor. Melatonin has been reported to serve as an indirect antioxidant via the stimulation and induction of antioxidant enzymes as superoxide dismutase (SOD) and glutathione peroxidase (Gpx) in several tissues.

AIM

: To assess whether the melatonin status, presence of labor at the time of birth and the time of delivery influence the extracellular antioxidative enzymes and DNA oxidative stress in newborns.

METHODS

The extracellular antioxidative status and oxidative stress were analyzed by measuring the concentrations of the SOD3, Gpx3 and 8-hydroxydeoxyguanosine (8-OHdG) in the cord blood of 135 newborns. Newborns delivered during the day and at night and newborns delivered by spontaneous vaginal delivery (labor group) or elective caesarean section delivery (no labor group) were studied.

OUTCOME MEASURES

The concentration of melatonin, SOD3, Gpx3 and 8-OHdG.

RESULTS

Independent of the time of delivery, we found significantly higher melatonin, SOD3 and Gpx3 but lower 8-OHdG concentrations in the labor group than in the no labor group. We did not observe a correlation between the concentration of melatonin and SOD3, Gpx3 or 8-OHdG, or a day-night difference in SOD3, Gpx3 or 8-OHdG.

CONCLUSION

Our findings suggest that oxidative stress during labor leads to an elevation of melatonin, SOD3 and Gpx3 in the fetal circulation, protecting the newborn from serious impairment, which is reflected by lower 8-OHdG levels. The melatonin status at the time of birth does not influence the extracellular SOD3 or Gpx3 concentrations.

Cloning of a putative extracellular Cu/Zn superoxide dismutase and functional differences of superoxide dismutases in invasive and indigenous whiteflies

Superoxide dismutases (SODs) are a group of important antioxidant defense enzymes. In this study, a putative extracellular Cu/Zn superoxide dismutase (ecCuZnSOD) complementary DNA was cloned and characterized from the whitefly, Bemisia tabaci. Quantitative polymerase chain reaction analysis showed that the expression level of BtecCuZnSOD was more than 10-fold higher in the invasive Middle East Asia Minor 1 (MEAM1) than in the native Asia II 3 species of the B. tabaci species complex. After exposure to low temperature (4 °C), the expression of Bt-ecCuZnSOD gene was significantly up-regulated in MEAM1 but not in Asia II 3. Furthermore, the expression level of B. tabaci intracellular CuZnSOD (Bt-icCuZnSOD), Bt-ecCuZnSOD and mitochondrial MnSOD (Bt-mMnSOD) was compared after transferring MEAM1 and Asia II 3 whiteflies from favorable (cotton) to unfavorable host plants (tobacco). On cotton, both CuZnSOD genes were expressed at a higher level in MEAM1 compared with Asia II 3. Interestingly, after transferring onto tobacco, the expression of Bt-ecCuZnSOD was significantly induced in Asia II 3 but not in MEAM1. On the other hand, while Bt-mMnSOD was expressed equally in both species on cotton, Bt-mMnSOD messenger RNA was up-regulated in MEAM1 on tobacco. Consistently, enzymatic activity assays of CuZnSOD and MnSOD demonstrated that CuZnSOD might play an important protective role against oxidative stress in Asia II 3, whereas MnSOD activation was critical for MEAM1 whiteflies during host adaptation. Taken together, our results suggest that the successful invasion of MEAM1 is correlated with its constitutive high activity of CuZnSOD and inducible expression of MnSOD under stress conditions.

Cloning and expression analysis of Drosophila extracellular Cu Zn superoxide dismutase

In the present study, we cloned and sequenced the mRNAs of the Sod3 [extracellular Cu Zn SOD (superoxide dismutase)] gene in Drosophila and identified two mRNA products formed by alternative splicing. These products code for a long and short protein derived from the four transcripts found in global expression studies (Flybase numbers Dmel\CG9027, FBgn0033631). Both mRNA process variants contain an extracellular signalling sequence, a region of high homology to the Sod1 (cytoplasmic Cu Zn SOD) including a conserved AUG start, with the longer form also containing a hydrophobic tail. The two fully processed transcripts are homologous to Caenorhabditis elegans Sod3 mRNA showing the same processing pattern. Using an established KG p-element+ insertion line (KG06029), we demonstrate that the Sod3 codes for an active Cu Zn SOD. We found differing expression patterns across sex with higher levels of expression of Sod3 in females. There is a correlation of Sod1 and Sod3 gene expression and activity that can explain why Sod3 was not seen in earlier studies of Sod1. Finally, we found no effect on lifespan with the Sod3 hypomorph mutation (Sod3^KG06029) but did observe a significant increase in resistance to paraquat and H₂O₂ (hydrogen peroxide).

Extracellular superoxide dismutase (SOD3) in Drosophila is characterized for mRNA splice variants and sex-specific expression. A SOD3 mutant reveals no effect on longevity, enhanced resistance to paraquat and H₂0₂, and provided evidence suggesting an interaction with other superoxide dismutases.

Diaphragm dysfunction caused by sphingomyelinase requires the p47(phox) subunit of NADPH oxidase

Sphingomyelinase (SMase) activity is elevated in inflammatory states and may contribute to muscle weakness in these conditions. Exogenous SMase depresses muscle force in an oxidant-dependent manner. However, the pathway stimulated by SMase that leads to muscle weakness is unclear. In non-muscle cells, SMase activates the Nox2 isoform of NADPH oxidase, which requires the p47(phox) subunit for enzyme function. We targeted p47(phox) genetically and pharmacologically (apocynin) to examine the role of NADPH oxidase on SMase-induced increase in oxidants and diaphragm weakness. SMase increased cytosolic oxidants (arbitrary units: control 203±15, SMase 276±22; P<0.05) and depressed maximal force in wild type mice (N/cm(2): control 20±1, SMase 16±0.6; P<0.05). However, p47(phox) deficient mice were protected from increased oxidants (arbitrary units: control 217±27, SMase 224±17) and loss of force elicited by SMase (N/cm(2): control 20±1, SMase 19±1). Apocynin appeared to partially prevent the decrease in force caused by SMase (n=3 mice/group). Thus, our study suggests that NADPH oxidase plays an important role on oxidant-mediated diaphragm weakness triggered by SMase. These observations provide further evidence that NADPH oxidase modulates skeletal muscle function.

Oxidative Stress and Therapeutic Development in Lung Diseases

Oxidative stress has many implications in the pathogenesis of lung diseases. In this review, we provide an overview of Reactive Oxygen Species (ROS) and nitrogen (RNS) species and antioxidants, how they relate to normal physiological function and the pathophysiology of different lung diseases, and therapeutic strategies. The production of ROS/RNS from endogenous and exogenous sources is first discussed, followed by antioxidant systems that restore oxidative balance and cellular homeostasis. The contribution of oxidant/antioxidant imbalance in lung disease pathogenesis is also discussed. An overview of therapeutic strategies is provided, such as augmenting NO bioactivity, blocking the production of ROS/RNS and replacement of deficient antioxidants. The limitations of current strategies and failures of clinical trials are then addressed, followed by discussion of novel experimental approaches for the development of improved antioxidant therapies.

Diabetic cardiomyopathy is associated with defective myocellular copper regulation and both defects are rectified by divalent copper chelation

BACKGROUND

Heart disease is the leading cause of death in diabetic patients, and defective copper metabolism may play important roles in the pathogenesis of diabetic cardiomyopathy (DCM). The present study sought to determine how myocardial copper status and key copper-proteins might become impaired by diabetes, and how they respond to treatment with the Cu (II)-selective chelator triethylenetetramine (TETA) in DCM.

METHODS

Experiments were performed in Wistar rats with streptozotocin (STZ)-induced diabetes with or without TETA treatment. Cardiac function was analyzed in isolated-perfused working hearts, and myocardial total copper content measured by particle-induced x-ray emission spectroscopy (PIXE) coupled with Rutherford backscattering spectrometry (RBS). Quantitative expression (mRNA and protein) and/or activity of key proteins that mediate LV-tissue-copper binding and transport, were analyzed by combined RT-qPCR, western blotting, immunofluorescence microscopy, and enzyme activity assays. Statistical analysis was performed using Student's t-tests or ANOVA and p-values of < 0.05 have been considered significant.

RESULTS

Left-ventricular (LV) copper levels and function were severely depressed in rats following 16-weeks' diabetes, but both were unexpectedly normalized 8-weeks after treatment with TETA was instituted. Localized myocardial copper deficiency was accompanied by decreased expression and increased polymerization of the copper-responsive transition-metal-binding metallothionein proteins (MT1/MT2), consistent with impaired anti-oxidant defences and elevated susceptibility to pro-oxidant stress. Levels of the high-affinity copper transporter-1 (CTR1) were depressed in diabetes, consistent with impaired membrane copper uptake, and were not modified by TETA which, contrastingly, renormalized myocardial copper and increased levels and cell-membrane localization of the low-affinity copper transporter-2 (CTR2). Diabetes also lowered indexes of intracellular (IC) copper delivery via the copper chaperone for superoxide dismutase (CCS) to its target cuproenzyme, superoxide dismutase-1 (SOD1): this pathway was rectified by TETA treatment, which normalized SOD1 activity with consequent bolstering of anti-oxidant defenses. Furthermore, diabetes depressed levels of additional intracellular copper-transporting proteins, including antioxidant-protein-1 (ATOX1) and copper-transporting-ATPase-2 (ATP7B), whereas TETA elevated copper-transporting-ATPase-1 (ATP7A).

CONCLUSIONS

Myocardial copper deficiency and defective cellular copper transport/trafficking are revealed as key molecular defects underlying LV impairment in diabetes, and TETA-mediated restoration of copper regulation provides a potential new class of therapeutic molecules for DCM.

Mitochondrial membrane potential in 2-cell stage embryos correlates with the success of preimplantation development

Hormonal stimulation in superovulation induces female mice to ovulate more oocytes than spontaneous ovulation. Because the superovulated oocytes contain a number of oocytes that normally regress before spontaneous ovulation or immature oocytes, the development of some embryos that derive from these oocytes by IVF is prevented. Therefore, the quality of superovulated oocytes should differ from that of spontaneously ovulated oocytes. In this study, we evaluated the quality of superovulated oocytes, by examining 1- and 2-cell stage embryos, in which the development mainly depends on the maternal mRNA, proteins, and mitochondria that are contained in the oocytes, and we then measured the mitochondrial membrane potential (ΔΨm) of the 1- and 2-cell stage,in vivo-fertilized, and IVF embryos. The ΔΨmof 1-cell stage IVF embryos was lower than that ofin vivo-fertilized embryos; however, there was no difference between IVF embryos. During the developmental process from 1- to 2-cell stage, the ΔΨmofin vivo-fertilized embryos was highly upregulated, whereas a number of IVF embryos remained unchanged. As a result, 2-cell stage embryos were divided into two groups: high- and low- ΔΨm2-cell stage IVF embryos. The development of low-ΔΨm2-cell stage IVF embryos tended to be arrested after the 2-cell stage. These results indicated that the upregulation of ΔΨmduring the 1- to 2-cell stage was important in the development of early preimplantation embryos; there were some defects in the mitochondria of superovulated oocytes, which prevented their development.

The cellular distribution of extracellular superoxide dismutase in macrophages is altered by cellular activation but unaffected by the naturally occurring R213G substitution

Extracellular superoxide dismutase (EC-SOD) is responsible for the dismutation of the superoxide radical produced in the extracellular space and known to be expressed by inflammatory cells, including macrophages and neutrophils. Here we show that EC-SOD is produced by resting macrophages and associated with the cell surface via the extracellular matrix (ECM)-binding region. Upon cellular activation induced by lipopolysaccharide, EC-SOD is relocated and detected both in the cell culture medium and in lipid raft structures. Although the secreted material presented a significantly reduced ligand-binding capacity, this could not be correlated to proteolytic removal of the ECM-binding region, because the integrity of the material recovered from the medium was comparable to that of the cell surface-associated protein. The naturally occurring R213G amino acid substitution located in the ECM-binding region of EC-SOD is known to affect the binding characteristics of the protein. However, the analysis of macrophages expressing R213G EC-SOD did not present evidence of an altered cellular distribution. Our results suggest that EC-SOD plays a dynamic role in the inflammatory response mounted by activated macrophages.

Gastroprotective effect of ethanolic extract of Curcuma xanthorrhiza leaf against ethanol-induced gastric mucosal lesions in Sprague-Dawley rats

Herbal medicines appeared promising in prevention of many diseases. This study was conducted to investigate the gastroprotective effect of Curcuma xanthorrhiza leaf in the rats induced gastric ulcer by ethanol. Normal and ulcer control received carboxymethycellulose (5 mL/kg) orally, positive control was administered with 20 mg/kg omeprazole (reference drug) and 2 groups were received 250 mg/kg and 500 mg/kg of the leaf extract, respectively. To induce of gastric ulcers formation, ethanol (5 mL/kg) was given orally to all groups except normal control. Gross ulcer areas, histology, and amount of prostaglandin E₂, superoxide dismutase and malondialdehyde were assessed to determine the potentiality of extract in prevention against gastric ulcers. Oral administration of extract showed significant gastric protection effect as the ulcer areas was remarkably decreased. Histology observation showed less edema and leucocytes infiltration as compared with the ulcer control which exhibited severe gastric mucosa injury. Furthermore, the leaf extract elevated the mucus weight, level of prostaglandin E₂ and superoxide dismutase. The extract also reduced malondialdehyde amount significantly. Results showed leaf extract of Curcuma xanthorrhiza can enhanced the gastric protection and sustained the integrity of gastric mucosa structure. Acute toxicity test did not showed any sign of toxicity (2 g/kg and 5 g/kg).

Human extracellular superoxide dismutase (EC-SOD) expression in transgenic chicken

Extracellular superoxide dismutase (EC-SOD) is a metalloprotein and functions as an antioxidant enzyme. In this study, we used lentiviral vectors to generate transgenic chickens that express the human EC-SOD gene. The recombinant lentiviruses were injected into the subgerminal cavity of freshly laid eggs. Subsequently, the embryos were incubated to hatch using phases II and III of the surrogate shell ex vivo culture system. Of 158 injected embryos, 16 chicks (G0) hatched and were screened for the hEC-SOD by PCR. Only 1 chick was identified as a transgenic bird containing the transgene in its germline. This founder (G0) bird was mated with wild-type hens to produce transgenic progeny, and 2 transgenic chicks (G1) were produced. In the generated transgenic hens (G2), the hEC-SOD protein was expressed in the egg white and showed antioxidant activity. These results highlight the potential of the chicken for production of biologically active proteins in egg white. [BMB Reports 2013; 46(8): 404-409]

Redox proteins and radiotherapy

Although conventional radiotherapy can directly damage DNA and other organic molecules within cells, most of the damage and the cytotoxicity of such ionising radiation, comes from the production of ions and free radicals produced via interactions with water. This 'indirect effect', a form of oxidative stress, can be modulated by a variety of systems within cells that are in place to, in normal situations, maintain homeostasis and redox balance. If cancer cells express high levels of antioxidant redox proteins, they may be more resistant to radiation and so targeting such systems may be a profitable strategy to increase therapeutic efficacy of conventional radiotherapy. An overview, with exemplars, of the main systems regulating redox homeostasis is supplied and discussed in relation to their use as prognostic and predictive biomarkers, and how targeting such proteins and systems may increase radiosensitivity and, potentially, improve the radiotherapeutic response.

Angiotensin II-Superoxide Signaling and Arterial Baroreceptor Function in Type-1 Diabetes Mellitus

Diabetes is a major world health problem. Growing evidence from both clinical trials and animal experiments has clearly confirmed that arterial baroreflex dysfunction is a feature of type 1 diabetes, which links to prognosis and mortality of the type 1 diabetic patients. The arterial baroreflex normally regulates the blood pressure and heart rate through sensing changes of arterial vascular tension by the arterial baroreceptors in the aortic arch and carotid sinus. The aortic baroreceptor neuron located in the nodose ganglia is a primary afferent component of the arterial baroreflex. The functional changes of these neurons are involved in the arterial baroreflex dysfunction in the type 1 diabetes. Type 1 diabetes causes the overexpression and hyperactivation of hyperpolarization-activated cyclic nucleotide-gated (HCN) channels and further reduces cell excitability of the aortic baroreceptor neurons. The alterations of the HCN channels are regulated by angiotensin II-NADPH oxidase-superoxide signaling in the aortic baroreceptor neurons. From the present review, we can understand the possible mechanisms responsible for the attenuated arterial baroreflex in the type 1 diabetes. These findings are beneficial for improving quality of life and prognosis in patients with the type 1 diabetes mellitus.

Myocardial protective effect of extracellular superoxide dismutase gene modified bone marrow mesenchymal stromal cells on infarcted mice hearts

Aim: Extracellular superoxide dismutase (ecSOD) is a unique scavenger of superoxide anions and a promising target of gene therapy for ischemia/reperfusion injury (I/R). However, conventional gene therapies have limitation in effectiveness and efficiency. This study aimed to investigate the protective effects of ecSOD gene modified bone marrow mesenchymal stromal cells (BMSCs) on cardiac function improvement in mice infarcted heart. METHODS & RESULTS: BMSCs were isolated from Fluc⁺ transgenic mice (Tg FVB[Fluc⁺]) and transfected by adenovirus combined with human ecSOD gene. ELISA was performed to determine ecSOD protein level. Female syngeneic FVB mice were randomized into 5 groups: (1) Sham group (sham); (2) MI group (MI); (3) MI+BMSCs group (BMSC); (4) MI+BMSCs-vector group (BMSC-vector); (5) MI+ BMSCs-ecSOD group (BMSC-ecSOD). MI was accomplished by ligation of the left anterior descending artery. BMSCs (2x10⁶) were injected into the border zone of infarction. In vivo bioluminescence imaging (BLI) was performed to monitor transplanted BMSCs viability. Echocardiography and histological staining revealed that BMSCs-ecSOD significantly reduced myocardial infarction size and improved cardiac function. Lucigenin chemiluminescence, DHE and TUNEL staining demonstrated that BMSCs-ecSOD delivery reduced ROS level and cell apoptosis both in vivo and in vitro. Western blot assay revealed that ecSOD supplementation increased FoxO3a phosphorylation in cardiomyocytes. Moreover, quantitative real-time PCR showed that pro-apoptotic factors (bim and bax) were decreased while the anti-apoptotic factor mir-21 expression was increased after ecSOD intervention. CONCLUSION: Intra-myocardial transplantation of adenovirus-ecSOD transfected BMSCs could exert potential cardiac protection against MI, which may be partly through reduction of oxidative stress and improvement of BMSCs survival.

Oxidative injury in epilepsy: potential for antioxidant therapy?

Biological ill effects of oxidative injury from excess free radical production are implicated in many human conditions. Epilepsy is a chronic, dynamic neurological disorder associated with ongoing neuronal damage, particularly when uncontrolled. Oxidative injury may play a role in the initiation and progression of epilepsy, and therapies aimed at reducing oxidative stress may ameliorate tissue damage and favorably alter the clinical course. There is abundant in vivo evidence of oxidative injury in animal models of epilepsy and for efficacy of antioxidant therapy in reducing this injury in animal models of epileptogenesis. However, there is sparse direct clinical data on the use of antioxidants in human epilepsy. This review examines the evidence for the role of oxidative injury in epilepsy, the rationale for use of antioxidant therapy in epilepsy and appraises the current clinical performance of the studies of antioxidant therapies.

A pilot study in rhesus macaques to assess the treatment efficacy of a small molecular weight catalytic metalloporphyrin antioxidant (AEOL 10150) in mitigating radiation-induced lung damage

The objective of this pilot study was to explore whether administration of a catalytic antioxidant, AEOL 10150 (C48H56C15MnN12), could reduce radiation-induced lung injury and improve overall survival when administered after 11.5 Gy of whole thorax lung irradiation in a non-human primate model. Thirteen animals were irradiated with a single exposure of 11.5 Gy, prescribed to midplane, and delivered with 6 MV photons at a dose rate of 0.8 Gy min. Beginning at 24 h post irradiation, the AEOL 10150 cohort (n = 7) received daily subcutaneous injections of the catalytic antioxidant at a concentration of 5 mg kg for a total of 4 wk. All animals received medical management, including dexamethasone, based on clinical signs during the planned 180-d in-life phase of the study. All decedent study animals were euthanized for failure to maintain saturation of peripheral oxygen > 88% on room air. Exposure of the whole thorax to 11.5 Gy resulted in radiation-induced lung injury in all animals. AEOL 10150, as administered in this pilot study, demonstrated potential efficacy as a mitigator against fatal radiation-induced lung injury. Treatment with the drug resulted in 28.6% survival following exposure to a radiation dose that proved to be 100% fatal in the control cohort (n = 6). Computed tomography scans demonstrated less quantitative radiographic injury (pneumonitis, fibrosis, effusions) in the AEOL 10150-treated cohort at day 60 post-exposure, and AEOL 10150-treated animals required less dexamethasone support during the in-life phase of the study. Analysis of serial plasma samples suggested that AEOL 10150 treatment led to lower relative transforming growth factor-Beta-1 levels when compared with the control animals. The results of this pilot study demonstrate that treatment with AEOL 10150 results in reduced clinical, radiographic, anatomic, and molecular evidence of radiation-induced lung injury and merits further study as a medical countermeasure against radiation-induced pulmonary injury.

Markers of Oxidative Stress during Diabetes Mellitus

The prevalence of diabetes mellitus is rising all over the world. Uncontrolled state of hyperglycemia due to defects in insulin secretion/action leads to a variety of complications including peripheral vascular diseases, nephropathy, neuropathy, retinopathy, morbidity, and/or mortality. Large body of evidence suggests major role of reactive oxygen species/oxidative stress in development and progression of diabetic complications. In the present paper, we have discussed the recent researches on the biomarkers of oxidative stress during type 2 diabetes mellitus.

Oxidants and redox signaling in acute lung injury

Acute lung injury (ALI) and its more severe form of clinical manifestation, the acute respiratory distress syndrome is associated with significant dysfunction in air exchange due to inflammation of the lung parenchyma. Several factors contribute to the inflammatory process, including hypoxia (inadequate oxygen), hyperoxia (higher than normal partial pressure of oxygen), inflammatory mediators (such as cytokines), infections (viral and bacterial), and environmental conditions (such as cigarette smoke or noxious gases). However, studies over the past several decades suggest that oxidants formed in the various cells of the lung including endothelial, alveolar, and epithelial cells as well as lung macrophages and neutrophils in response to the factors mentioned above mediate the pathogenesis of ALI. Oxidants modify cellular proteins, lipids, carbohydrates, and DNA to cause their aberrant function. For example, oxidation of lipids changes membrane permeability. Interestingly, recent studies also suggest that spatially and temporally regulated production of oxidants plays an important role antimicrobial defense and immunomodulatory function (such as transcription factor activation). To counteract the oxidants an arsenal of antioxidants exists in the lung to maintain the redox status, but when overwhelmed tissue injury and exacerbation of inflammation occurs. We present below the current understanding of the pathogenesis of oxidant-mediated ALI.

Surface modification by argon plasma treatment improves antioxidant defense ability of CHO-k1 cells on titanium surfaces

Titanium is one of the most used materials in implants and changes in its surface can modify the cellular functional response to better implant fixation. An argon plasma treatment generates a surface with improved mechanical proprieties without modifying its chemical composition. Oxidative stress induced by biomaterials is considered one of the major causes of implant failure and studies in this field are fundamental to evaluate the biocompatibility of a new material. Therefore, in this work, induction of oxidative stress by titanium surfaces subjected to plasma treatment (PTTS) was evaluated. The viability of CHO-k1 cells was higher on PTTS discs. Cells grown on titanium surfaces are subjected to intracellular oxidative stress. Titanium discs subjected to the plasma treatment induced less oxidative stress than the untreated ones, which resulted in improved cellular survival. These were associated with improved cellular antioxidant response in Plasma Treated Titanium Surface (PTTS). Furthermore, a decrease in protein and DNA oxidative damage was observed on cells grown on the roughed surface when compared to the smooth one. In conclusion, our data suggest that the treatment of titanium with argon plasma may improve its biocompatible, thus improving its performance as implants or as a scaffold in tissue engineering.

Copper transporter ATP7A protects against endothelial dysfunction in type 1 diabetic mice by regulating extracellular superoxide dismutase

Oxidative stress and endothelial dysfunction contribute to vascular complication in diabetes. Extracellular superoxide dismutase (SOD3) is one of the key antioxidant enzymes that obtains copper via copper transporter ATP7A. SOD3 is secreted from vascular smooth muscles cells (VSMCs) and anchors at the endothelial surface. The role of SOD3 and ATP7A in endothelial dysfunction in type 1 diabetes mellitus (T1DM) is entirely unknown. Here we show that the specific activity of SOD3, but not SOD1, is decreased, which is associated with increased O2(•-) production in aortas of streptozotocin-induced and genetically induced Ins2(Akita) T1DM mice. Exogenous copper partially rescued SOD3 activity in isolated T1DM vessels. Functionally, acetylcholine-induced, endothelium-dependent relaxation is impaired in T1DM mesenteric arteries, which is rescued by SOD mimetic tempol or gene transfer of SOD3. Mechanistically, ATP7A expression in T1DM vessels is dramatically decreased whereas other copper transport proteins are not altered. T1DM-induced endothelial dysfunction and decrease of SOD3 activity are rescued in transgenic mice overexpressing ATP7A. Furthermore, SOD3-deficient T1DM mice or ATP7A mutant T1DM mice augment endothelial dysfunction and vascular O2(•-) production versus T1DM mice. These effects are in part due to hypoinsulinemia in T1DM mice, since insulin treatment, but not high glucose, increases ATP7A expression in VSMCs and restores SOD3 activity in the organoid culture of T1DM vessels. In summary, a decrease in ATP7A protein expression contributes to impaired SOD3 activity, resulting in O2(•-) overproduction and endothelial dysfunction in blood vessels of T1DM. Thus, restoring copper transporter function is an essential therapeutic approach for oxidant stress-dependent vascular and metabolic diseases.