Extracellular superoxide dismutase in biology and medicine

Genomic organization of the cytosolic manganese superoxide dismutase gene from the Pacific white shrimp, Litopenaeus vannamei, and its response to thermal stress

Cytosolic manganese superoxide dismutase (cMnSOD) is an important antioxidant enzyme which catalyzes the conversion of superoxides to oxygen and hydrogen peroxide in several organisms. In the Pacific white shrimp, Litopenaeus vannamei, three cMnSOD genes (LvcMnSOD1-3) have previously been characterized. Here, the genomic structure of LvcMnSOD2 and its mRNA expression in response to thermal stress was examined. Analysis of the nucleotide sequence demonstrated that LvcMnSOD2 is comprised of 2392 bp spanning from the ATG translation start site to the stop codon and contains six exons interrupted by five introns. The 5' region upstream of the LvcMnSOD2 gene contains several putative regulatory elements but lacks the accepted TATA sequence. The putative transcription factor binding elements that may be involved in LvcMnSOD2 mRNA expression level include activator protein-1 (AP-1), cAMP response element binding protein (CREB), upstream stimulatory factor (USF), CAAT-enhancer binding protein (C/EBP), nuclear factor-κB (NF-κB) and heat shock regulatory element (HSE). In addition, we compared the 5' upstream sequences of the LvcMnSOD2 gene between two shrimp strains that are resistant or susceptible to Taura syndrome virus (TSV), respectively, which revealed the absence of the USF and C/EBP elements at positions -2125 and -1986, respectively, in the TSV-susceptible shrimp line. Moreover, genomic variations between the two shrimp strains were detected in some of the putative C/EBP, USF, HSE and NF-κB transcription factor binding elements. That these genomic variations might be involved in the TSV resistance as well as in stress responses remains to be evaluated. The presence of 15 putative HSEs suggests that the expression of LvcMnSOD2 is regulated under thermal stress. Here, we found that in response to a 1 or 3 h thermal stress (35 °C), the mRNA expression levels of LvcMnSOD2 were significantly increased and then gradually decreased in the recovering phase at room temperature (25 °C) to control levels by 3 h after the heat shock. Thus, the antioxidant system may be induced to protect cells from the oxidative damage caused by thermal stress. The genomic organization of LvcMnSOD2 likely provides a clue to the mechanisms that might regulate the antioxidant defense pathway in shrimps and so potentially in marine invertebrates.

Characterization and metal-induced gene transcription of two new copper zinc superoxide dismutases in the solitary ascidian Ciona intestinalis

Antioxidant enzymes are known to protect living organisms against the oxidative stress risk, also induced by metals. In the present study, we describe the purification and molecular characterization of two Cu,Zn superoxide dismutases (SODs), referred to as Ci-SODa and Ci-SODb, from Ciona intestinalis, a basal chordate widely distributed in temperate shallow seawater. The putative amino acid sequences were compared with Cu,Zn SODs from other metazoans and phylogenetic analyses indicate that the two putative Ci-SODs are more related to invertebrate SODs than vertebrate ones. Both phylogenetic and preliminary homology modeling analyses suggest that Ci-SODa and Ci-SODb are extracellular and intracellular isoform, respectively. The mRNA of the two Cu,Zn SODs was localized in hemocytes and in ovarian follicular cells, as revealed by in situ hybridization. The time course of SOD mRNA levels in the presence of three different metals showed upregulation of ci-soda and inhibition of ci-sodb. Spectrophotometric analysis confirms the presence of SOD activity in Ciona tissues. Our in silico analyses of the ci-soda promoter region revealed putative consensus sequences similar to mammalian metal-responsive elements (MRE), suggesting that the transcription of these genes directly depends on metals. These data emphasize the importance of complex metal regulation of ci-soda and ci-sodb transcription, as components of an efficient detoxification pathway allowing the survival of C. intestinalis in continued, elevated presence of metals in the environment.

Proteomic analysis of human dental cementum and alveolar bone

Dental cementum (DC) is a bone-like tissue covering the tooth root and responsible for attaching the tooth to the alveolar bone (AB) via the periodontal ligament (PDL). Studies have unsuccessfully tried to identify factors specific to DC versus AB, in an effort to better understand DC development and regeneration. The present study aimed to use matched human DC and AB samples (n=7) to generate their proteomes for comparative analysis. Bone samples were harvested from tooth extraction sites, whereas DC samples were obtained from the apical root portion of extracted third molars. Samples were denatured, followed by protein extraction reduction, alkylation and digestion for analysis by nanoAcquity HPLC system and LTQ-FT Ultra. Data analysis demonstrated that a total of 318 proteins were identified in AB and DC. In addition to shared proteins between these tissues, 105 and 83 proteins exclusive to AB or DC were identified, respectively. This is the first report analyzing the proteomic composition of human DC matrix and identifying putative unique and enriched proteins in comparison to alveolar bone. These findings may provide novel insights into developmental differences between DC and AB, and identify candidate biomarkers that may lead to more efficient and predictable therapies for periodontal regeneration.

BIOLOGICAL SIGNIFICANCE

Periodontal disease is a highly prevalent disease affecting the world population, which involves breakdown of the tooth supporting tissues, the periodontal ligament, alveolar bone, and dental cementum. The lack of knowledge on specific factors that differentiate alveolar bone and dental cementum limits the development of more efficient and predictable reconstructive therapies. In order to better understand cementum development and potentially identify factors to improve therapeutic outcomes, we took the unique approach of using matched patient samples of dental cementum and alveolar bone to generate and compare a proteome list for each tissue. A potential biomarker for dental cementum was identified, superoxide dismutase 3 (SOD3), which is found in cementum and cementum-associated cells in mouse, pig, and human tissues. These findings may provide novel insights into developmental differences between alveolar bone and dental cementum, and represent the basis for improved and more predictable therapies.

SOD2 in mitochondrial dysfunction and neurodegeneration

The brain is a highly metabolically active tissue that critically relies on oxidative phosphorylation as a means for maintaining energy. One result of this process is the production of potentially damaging radicals such as the superoxide anion (O2(-)). Superoxide has the capacity to damage components of the electron transport chain and other cellular constituents. Eukaryotic systems have evolved defenses against such damaging moieties, the chief member of which is superoxide dismutase (SOD2), an enzyme that efficiently converts superoxide to the less reactive hydrogen peroxide (H2O2), which can freely diffuse across the mitochondrial membrane. Loss of SOD2 activity can result in numerous pathological phenotypes in metabolically active tissues, particularly within the central nervous system. We review SOD2's potential involvement in the progression of neurodegenerative diseases such as stroke and Alzheimer and Parkinson diseases, as well as its potential role in "normal" age-related cognitive decline. We also examine in vivo models of endogenous oxidative damage based upon the loss of SOD2 and associated neurological phenotypes in relation to human neurodegenerative disorders.

Effects of imperatorin on nicotine-induced anxiety- and memory-related responses and oxidative stress in mice

The purpose of the reported experiments was to examine the effects of imperatorin [9-[(3-methylbut-2-en-1-yl)oxy]-7H-furo[3,2-g]chromen-7-one] on anxiety and memory-related responses induced by nicotine in mice and their relation to the level of nicotine-induced oxidative stress in brain as well as in the hippocampus and the prefrontal cortex. Male Swiss mice were tested for anxiety in the elevated plus maze test (EPM), and for cognition using passive avoidance (PA) procedures. Imperatorin, purified by high-speed counter-current chromatography from methanol extract of fruits of Angelica officinalis, acutely administered at the doses of 10 and 20mg/kg impaired the anxiogenic effect of nicotine (0.1mg/kg, s.c.). Furthermore, acute injections of subthreshold dose of imperatorin (1mg/kg, i.p.) improved processes of memory acquisition when co-administered with nicotine used at non-active dose of 0.05 mg/kg, s.c. Additionally, repeated administration of imperatorin (1mg/kg, i.p., twice daily, for 6 days) improved different stages of memory processes (both acquisition and consolidation) when injected in combination with non-active dose of nicotine (0.05 mg/kg, s.c.) in the PA task. Oxidative stress was assessed by determination of antioxidant enzymes (glutathione peroxidases (GPx), superoxide dismutase (SOD), glutathione reductase (GR)) activities as well as of malondialdehyde (MDA) concentration in the whole brain, the hippocampus and the prefrontal cortex after repeated administration of imperatorin (1mg/kg, 6 days) and single nicotine injection (0.05 mg/kgs.c.) on the seventh day. The results of our research suggest strong behavioural interaction between imperatorin and nicotine at the level of anxiety- and cognitive-like processes. Furthermore, imperatorin inhibited nicotine-induced changes in examined indicators of oxidative stress, especially in the hippocampus and the cortex.

IFNγ-mediated inhibition of cell proliferation through increased PKCδ-induced overexpression of EC-SOD

Extracellular superoxide dismutase (EC-SOD) overexpression modulates cellular responses such as tumor cell suppression and is induced by IFNγ. Therefore, we examined the role of EC-SOD in IFNγ-mediated tumor cell suppression. We observed that the dominant-negative protein kinase C delta (PKCδ) suppresses IFNγ-induced EC-SOD expression in both keratinocytes and melanoma cells. Our results also showed that PKCδ-induced ECSOD expression was reduced by pretreatment with a PKCspecific inhibitor or a siRNA against PKCδ. PKCδ-induced ECSOD expression suppressed cell proliferations by the up-regulation of p21 and Rb, and the downregulation of cyclin A and D. Finally, we demonstrated that increased expression of EC-SOD drastically suppressed lung melanoma proliferation in an EC-SOD transgenic mouse via p21 expression. In summary, our findings suggest that IFNγ-induced EC-SOD expression occurs via activation of PKCδ. Therefore, the upregulation of EC-SOD may be effective for prevention of various cancers, including melanoma, via cell cycle arrest. [BMB Reports 2012; 45(11): 659-664]

Redox environment, free radical, and oxidative DNA damage

SIGNIFICANCE

Effective redox homeostasis is critical, and disruption of this process can have important cellular consequences. An array of systems protect the cell from potentially damaging reactive oxygen species (ROS), however if these systems are overwhelmed, for example, in aberrantly functioning cells, ROS can have a number of detrimental consequences, including DNA damage. Oxidative DNA damage can be repaired by a number of DNA repair pathways, such as base excision repair (BER).

RECENT ADVANCES

The role of ROS in oxidative DNA damage is well established, however, there is an emerging role for ROS and the redox environment in modulating the efficiency of DNA repair pathways targeting oxidative DNA lesions.

CRITICAL ISSUES

Oxidative DNA damage and modulation of DNA damage and repair by the redox environment are implicated in a number of diseases. Understanding how the redox environment plays such a critical role in DNA damage and repair will allow us to further understand the far reaching cellular consequence of ROS.

FUTURE DIRECTIONS

In this review, we discuss the detrimental effects of ROS, oxidative DNA damage repair, and the redox systems that exist to control redox homeostasis. We also describe how DNA pathways can be modulated by the redox environment and how the redox environment and oxidative DNA damage plays a role in disease.

Protective effect of C70-carboxyfullerene against oxidative-induced stress on postmitotic muscle cells

Satellite muscle cells play an important role in regeneration of skeletal muscle. However, they are particularly vulnerable to oxidative stress. Herein, we address our efforts on the cytoprotective activities of carboxyfullerenes with different cage size (C60 vs C70) and adduct number on postmitotic muscle cell (C2C12 cell). The correlation of the structural effect on the cytoprotective capability of carboxyfullerenes was evaluated. We find that quadri-malonic acid C70 fullerene (QF70) exhibits higher capability on protecting cells from oxidative-induced stress among these tested carboxyfullerenes. The accumulation of intracellular superoxide dismutase (SOD) is proposed to play an important role in their diverse antioxidative ability. Moreover, the pretreatment of QF70 could also obviously enhance the viability of myotubes originated from oxidative-stressed C2C12 cells, which facilitates the future application of carboxyfullerenes in tissue engineering and nanomedicine.

Widespread production of extracellular superoxide by heterotrophic bacteria

Superoxide and other reactive oxygen species (ROS) originate from several natural sources and profoundly influence numerous elemental cycles, including carbon and trace metals. In the deep ocean, the permanent absence of light precludes currently known ROS sources, yet ROS production mysteriously occurs. Here, we show that taxonomically and ecologically diverse heterotrophic bacteria from aquatic and terrestrial environments are a vast, unrecognized, and light-independent source of superoxide, and perhaps other ROS derived from superoxide. Superoxide production by a model bacterium within the ubiquitous Roseobacter clade involves an extracellular oxidoreductase that is stimulated by the reduced form of nicotinamide adenine dinucleotide (NADH), suggesting a surprising homology with eukaryotic organisms. The consequences of ROS cycling in immense aphotic zones representing key sites of nutrient regeneration and carbon export must now be considered, including potential control of carbon remineralization and metal bioavailability.

Dietary lipid requirement on non-specific immune responses in juvenile grass carp (Ctenopharyngodon idella)

This study aimed to evaluate the dietary lipid requirement and its effects on liver oxidative status and non-specific immune responses of juvenile grass carp (Ctenopharyngodon idella). Purified diets with five dietary lipid levels (0%, 2.5%, 5%, 7.5% and 10%, fish oil/corn oil = 1:1) were each fed to triplicate groups of grass carp (mean initial weight: 6.57 ± 0.01 g) in a recirculating rearing system maintained at 27.5 ± 0.5 °C for 10 weeks. Percent weight gain was highest (P < 0.05) with 5% lipid and lowest in fish fed the lipid free control diet. Feed efficiency (FE) and protein efficiency ratio (PER) in fish followed the same pattern of percent weight gain. Fish fed with lipid containing diets had better non-specific immune response indexes (e.g. phagocytic activity, plasma peroxidase and lysozyme activity) and low-level of liver oxidation status than fish fed with the control diet. But excess dietary lipid supplement would bring over metabolic burden to liver. After the feeding trial, fish were challenged by Aeromonas hydrophila. Fish fed control diet obtained significantly (P < 0.05) lower survival rate. The survival rate was highest with 7.5% lipid. The results of this study indicated that proper dietary lipid supplementation enhanced the immune response of grass carp and improved the survival rate in the bacterial challenge, but excess dietary lipid may elevate liver oxidation rates of grass carp. Analysis by second-order regression of percent weight gain indicated that the optimal dietary lipid level in juvenile grass carp (6.6-35.5 g) is about 6.5%.

Effect of dietary copper on the growth performance, non-specific immunity and resistance to Aeromonas hydrophila of juvenile Chinese mitten crab, Eriocheir sinensis

An 8-week feeding trial was conducted to determine the dietary copper (Cu) on growth performance and immune responses of juvenile Chinese mitten crab Eriocheir sinensis. Six semi-purified diets with six copper levels (1.88, 11.85, 20.78, 40.34, 79.56 and 381.2 mg kg(-1) diet) of CuSO4·5H2O were fed to E. sinensis (0.45 ± 0.01 g). Each diet was fed to the crab in five replicates. The crab fed diets with 20.78 and 40.34 mg Cu kg(-1) diet had significantly greater weight gain and hemolymph oxyhemocyanin content than those fed diets with 1.88 and 381.2 mg Cu kg(-1) diet. Survival rates of crab were not significantly different between all treatment groups. The activities of copper-zinc superoxide dismutase (Cu-Zn SOD), phenoloxidase (PO), and total hemocyte count (THC) significantly increased when the supplementation of dietary copper reached 20.78-40.34 mg Cu kg(-1) diets. In the bacteria challenge experiment with Aeromonas hydrophila, survival rates significantly increased and reached a plateau when the dietary copper increased from 1.88 to 40.34 mg kg(-1), whereas significantly decreased when the dietary copper increased from 40.34 to 381.2 mg kg(-1). This study indicates that the level of dietary copper is important in regulating growth and immune response in crab.

Role of EC-SOD overexpression in preserving pulmonary angiogenesis inhibited by oxidative stress

Angiogenesis is one of the most important processes for normal lung development. Oxidative stress can impair the pulmonary angiogenesis, leading to chronic lung disease or Bronchopulmonary dysplasia (BPD).

Loss of extracellular superoxide dismutase induces severe IL-23-mediated skin inflammation in mice

Psoriasis is a common chronic and complex autoimmune inflammatory skin disorder. The histological characteristics of psoriasis are epidermal hyperplasia, mononuclear leukocyte infiltration into the dermis, and increased angiogenesis. However, the mechanisms involved in the pathogenesis of psoriasis remain unclear. Extracellular superoxide dismutase (EC-SOD) has antichemotactic activities. Because immune cell infiltration is seen in psoriatic lesions and psoriasis patients express low levels of EC-SOD, we hypothesized that the lack of EC-SOD induces more severe IL-23-mediated psoriasis-like skin inflammation. To test this hypothesis, we determined whether the loss of EC-SOD causes more severe IL-23-induced skin inflammation. Ear skin after IL-23 administration was thicker in EC-SOD knockout (KO) mice compared with wild-type mice. In addition, infiltration of CD4(+) T cells, macrophages, and dendritic cells (DCs) into IL-23 injection sites was more elevated in EC-SOD KO mice. The expression of proinflammatory cytokines and chemokines was also more elevated in EC-SOD KO mice, and EC-SOD KO DCs expressed a higher level of MHCII. Finally, EC-SOD transgenic mice showed much less severe IL-23-induced skin inflammation. Therefore, EC-SOD may inhibit IL-23-induced psoriasis-like inflammation through the inhibition of immune cell infiltration and immune responses. These results suggest that EC-SOD could be a possible candidate for management of psoriasis.

Superoxide dismutase 3 is induced by antioxidants, inhibits oxidative DNA damage and is associated with inhibition of estrogen-induced breast cancer

Epidemiological data and studies in rodent models strongly support the role of estrogens in the development of breast cancers. Oxidative stress has been implicated in this carcinogenic process. We have recently demonstrated that antioxidants vitamin C or butylated hydroxyanisole (BHA) severely inhibit 17β-estradiol (E2)-induced breast tumor development in female ACI rats. The objective of this study was to characterize the mechanism of antioxidant-mediated prevention of breast cancer. Female August Copenhagen Irish (ACI) rats were treated with E2, vitamin C, vitamin C + E2, BHA and BHA + E2 for up to 8 months. Superoxide dismutase 3 (SOD3) was suppressed in E2-exposed mammary tissues and in mammary tumors of rats treated with E2. This suppression was overcome by co-treatment of rats with E2 and vitamin C or BHA. 8-Hydroxydeoxyguanosine (8-OHdG) levels determined as a marker of oxidative DNA damage were higher in E2-exposed mammary tissues and in mammary tumors compared with age-matched controls. Vitamin C or BHA treatment significantly decreased E2-mediated increase in 8-OHdG levels in the mammary tissues and in MCF-10A cells. Increased DNA damage, colony and mammosphere formation, and migration in SOD3 knocked down MCF-10A cells, and nuclear translocation of SOD3 in vitamin C-treated mammary tissues and in MCF-10A cells suggest protective role of SOD3 against DNA damage and mammary carcinogenesis. Our studies further demonstrate that SOD3, but not SOD2 and SOD1, is induced by antioxidants and is regulated through NRF2. SOD3 may thus be an important gene in defense against oxidative stress and in the prevention of estrogen-mediated breast cancer.

Extracellular superoxide dismutase induced by dopamine in cultured astrocytes

Under some pathological conditions in brain, a large amount of superoxide anion (O(2)(-)) is produced, causing various cellular damages. Among three isozymes of superoxide dismutase (SOD), extracellular (EC)-SOD should play a role to detoxify O(2)(-) in extracellular space; however, a little is known about EC-SOD in brain. Although dopamine (DA) stored in the synaptic vesicle is stable, the excess leaked DA is spontaneously oxidized to yield O(2)(-) and reactive DA quinones, causing damages of dopaminergic neurons. In the present study, we examined the effects of DA on SOD expression in cultured rat cortical astrocytes. By means of RT-PCR, all mRNA of three isozymes of SOD could be detected; however, only EC-SOD was increased by DA exposure for 24 h, dose-dependently. The expression of EC-SOD protein and the cell-surface SOD activity in astrocytes also increased with 100 μM DA exposure. The increase of EC-SOD mRNA by DA was inhibited by a DA transporter inhibitor, GBR12909, whereas it was not changed by DA receptor antagonists, SKF-83566 (D1) and haloperidol (D2). Furthermore, a monoamine oxidase inhibitor, pargyline, and antioxidants, N-acetyl-L-cysteine and glutathione, also did not affect the DA-induced expression of EC-SOD mRNA. On the other hand, an inhibitor of nuclear factor kappaB (NF-κB), ammonium pyrrolidine-1-carbodithioate, suppressed the DA-induced expression of EC-SOD mRNA. These results suggest that DA incorporated into the cells caused the induction of EC-SOD mRNA followed by the enhancements of EC-SOD protein level and the enzyme activity, and that NF-κB activation is involved in the mechanisms of the EC-SOD induction. The regulation of EC-SOD in astrocytes surrounding dopaminergic neurons may contribute to the defensive mechanism against oxidative stress in brain.

Lung oxidative damage by hypoxia

One of the most important functions of lungs is to maintain an adequate oxygenation in the organism. This organ can be affected by hypoxia facing both physiological and pathological situations. Exposure to this condition favors the increase of reactive oxygen species from mitochondria, as from NADPH oxidase, xanthine oxidase/reductase, and nitric oxide synthase enzymes, as well as establishing an inflammatory process. In lungs, hypoxia also modifies the levels of antioxidant substances causing pulmonary oxidative damage. Imbalance of redox state in lungs induced by hypoxia has been suggested as a participant in the changes observed in lung function in the hypoxic context, such as hypoxic vasoconstriction and pulmonary edema, in addition to vascular remodeling and chronic pulmonary hypertension. In this work, experimental evidence that shows the implied mechanisms in pulmonary redox state by hypoxia is reviewed. Herein, studies of cultures of different lung cells and complete isolated lung and tests conducted in vivo in the different forms of hypoxia, conducted in both animal models and humans, are described.

Mechanistic overview of reactive species-induced degradation of the endothelial glycocalyx during hepatic ischemia/reperfusion injury

Endothelial cells are covered by a delicate meshwork of glycoproteins known as the glycocalyx. Under normophysiological conditions the glycocalyx plays an active role in maintaining vascular homeostasis by deterring primary and secondary hemostasis and leukocyte adhesion and by regulating vascular permeability and tone. During (micro)vascular oxidative and nitrosative stress, which prevails in numerous metabolic (diabetes), vascular (atherosclerosis, hypertension), and surgical (ischemia/reperfusion injury, trauma) disease states, the glycocalyx is oxidatively and nitrosatively modified and degraded, which culminates in an exacerbation of the underlying pathology. Consequently, glycocalyx degradation due to oxidative/nitrosative stress has far-reaching clinical implications. In this review the molecular mechanisms of reactive oxygen and nitrogen species-induced destruction of the endothelial glycocalyx are addressed in the context of hepatic ischemia/reperfusion injury as a model disease state. Specifically, the review focuses on (i) the mechanisms of glycocalyx degradation during hepatic ischemia/reperfusion, (ii) the molecular and cellular players involved in the degradation process, and (iii) its implications for hepatic pathophysiology. These topics are projected against a background of liver anatomy, glycocalyx function and structure, and the biology/biochemistry and the sources/targets of reactive oxygen and nitrogen species. The majority of the glycocalyx-related mechanisms elucidated for hepatic ischemia/reperfusion are extrapolatable to the other aforementioned disease states.

Mathematical and computational models of oxidative and nitrosative stress

The importance of nitric oxide (NO), superoxide (O2-), and peroxynitrite (ONOO-), interactions in physiologic functions and pathophysiological conditions such as cardiovascular disease, hypertension, and diabetes have been established extensively in in vivo and in vitro studies. Despite intense investigation of NO, O2-, and ONOO- biochemical interactions, fundamental questions regarding the role of these molecules remain unanswered. Mathematical models based on fundamental principles of mass balance and reaction kinetics have provided significant results in the case of NO. However, the models that include interaction of NO, O2-, and ONOO- have been few because of the complexity of these interactions. Not only do these mathematical and computational models provided quantitative knowledge of distributions and concentrations of NO, O2-, and ONOO- under normal physiologic and pathophysiologic conditions, they also can help to answer specific hypotheses. The focus of this review article is on the models that involve more than one of the 3 molecules (NO, O2-, and ONOO-). Specifically, kinetic models of O2- dismutase and tyrosine nitration and biotransport models in the microcirculation are reviewed. In addition, integrated experimental and computational models of dynamics of NO/O2-/ONOO- in diverse systems are reviewed.

Intracellular Copper Zinc Superoxide dismutase (icCuZnSOD) from Asian seabass (Lates calcarifer): molecular cloning, characterization and gene expression with reference to Vibrio anguillarum infection

Copper Zinc Superoxide dismutase (CuZnSOD) is the family of most important antioxidant metalloenzymes that protects tissues from damage by reactive oxygen species (ROS). In the present study, the intracellular copper zinc SOD from the Asian seabass Lates calcarifer (Lc-icCuZnSOD) was identified by RNA ligase mediated rapid amplification of cDNA ends (RLM-RACE) technique. The full-length cDNA of Lc-icCuZnSOD consisted of 809 nucleotides with an open-reading frame of 465 bp encoding 154 amino acids and N-Glycosylation site (NVTA) within. The predicted molecular mass of the protein is 15.84 kDa with an estimated pI of 5.52. The deduced amino acid sequence of Lc-icCuZnSOD shared high degree of homology with known CuZnSODs from other species. CuZn binding sites (H47, H49, H64, and H121 for Cu(2+) and H72, H81, and ASP84 for Zn(2+)), two cysteine residues (aa 58 and 147) that form a disulfide bond, and CuZnSOD family signature sequences (GFHVHAFGDNT, aa 45-55 and GNAGGRLACGVI, aa 139-150) were highly conserved among fish species. Temporal and tissue specific expression of Lc-icCuZnSOD was significantly differentially altered in Asian seabass challenged with Vibrio anguillarum indicating possible role in antioxidant activities involved in the innate immune defense mechanisms.

Superoxide dismutase 3 suppresses hyaluronic acid fragments mediated skin inflammation by inhibition of toll-like receptor 4 signaling pathway: superoxide dismutase 3 inhibits reactive oxygen species-induced trafficking of toll-like receptor 4 to lipid rafts

AIMS

Hyaluronic acid (HA) is a component of the extracellular matrix and has been extensively applied for cosmetic, therapeutic, and antiaging purposes. However, HA fragments (HAFs) cause adverse effects. Considering that UV-exposure produces HAF that accumulated on the skin, the role of HAF in skin inflammation and its precise mechanism needs to be clarified, and strategies for the prevention of skin inflammation are necessary.

RESULTS

We found that extracellular superoxide dismutase (SOD), SOD3, suppresses HAF-mediated skin inflammation, while HAF mediated skin inflammation, macrophages and dendritic cells (DCs) dominantly infiltrate, up-regulating inflammatory cytokines and chemokines receptors. However, keratinocytes indirectly responded to HAF. Instead, epidermis containing keratinocytes were stimulated by secreted molecules from HAF-treated macrophages or DC and produced inflammatory molecules including chemokines, which, in turn, led to skin inflammation. This orchestrated inflammatory response was inhibited by SOD3. In addition, SOD3 inhibited DC maturation by suppressing the expression of major histocompatibility complex II, CD80, and CD86. Interestingly, these responses did not occur in Toll-like receptor 4 (TLR4) deficient mice. Similar to lipopolysaccharide (LPS), HAF promoted TLR4 translocation into the lipid rafts to initiate signaling. This trafficking was mediated, at least in part, by NAPDH oxidase-dependent reactive oxygen species (ROS) generation. Subsequently, nuclear factor kappa B (NFκB) subunit, p65, was recruited the promoters of genes encoding inflammatory molecules. This inflammatory machinery was blocked by SOD3.

INNOVATION AND CONCLUSION

Thus, we propose that SOD3 might provide an effective strategy for the treatment of HAF-mediated skin inflammation.

Redox signaling at invasive microdomains in cancer cells

Redox signaling contributes to the regulation of cancer cell proliferation, survival, and invasion and participates in the adaptation of cancer cells to their microenvironment. NADPH oxidases are important mediators of redox signaling in normal and cancer cells. Redox signal specificity in normal cells is in part achieved by targeting enzymes that generate reactive oxygen species to specific subcellular microdomains such as focal adhesions, dorsal ruffles, lipid rafts, or caveolae. In a similar fashion, redox signal specificity during cancer cell invasion can be regulated by targeting reactive oxygen generation to invasive microdomains such as invadopodia. Here we summarize recent advances in the understanding of the redox signaling processes that control the cancer cell proinvasive program by modulating cell adhesion, migration, and proteolysis as well as the interaction of cancer cells with the tumor microenvironment. We focus on redox signaling events mediated by invadopodia NADPH oxidase complexes and their contribution to cancer cell invasion.

The effect of dietary methionine and white tea on oxidative status of gilthead sea bream (Sparus aurata)

Free radicals are continuously generated during an organism's lifetime. In order to understand the involvement in the oxidative status of fish, methionine and white tea were assayed as antioxidant supplements in diets for gilthead sea bream (Sparus aurata). For the purpose of this study, four isonitrogenous and isolipidic diets were formulated to contain 45 % of protein and 18 % lipid and 0·3 % methionine (Met diet), 2·9 % white tea dry leaves (Tea diet) and 2·9 % of white tea dry leaves + 0·3 % methionine (Tea + Met diet). An unsupplemented diet was used as the control. Key enzymatic antioxidant defences, superoxide dismutase (SOD) isoenzyme profile, total, reduced and oxidised glutathione and oxidative damage markers were determined. The results showed that dietary methionine supplementation increased liver SOD activity, while white tea induced higher hepatic catalase activity. Dietary white tea induced a notable increase in Mn-SOD isoenzyme. This is the first study to provide evidence that dietary tea inclusion in fish feeding could be an important source of Mn with metabolic repercussions on antioxidant mechanisms.

Regulation of skin inflammation and angiogenesis by EC-SOD via HIF-1α and NF-κB pathways

Extracellular superoxide dismutase (EC-SOD) is an antioxidant enzyme that breaks down superoxide anion into oxygen and hydrogen peroxide in extracellular spaces and plays key roles in controlling pulmonary and vascular diseases in response to oxidative stresses. We aimed to investigate the role of EC-SOD in angiogenesis and inflammation in chronic inflammatory skin disorders such as psoriasis. Overexpressed EC-SOD reduced expression of angiogenic factors and proinflammatory mediators in hypoxia-induced keratinocytes and in ultraviolet B-irradiated mice, whereas the expression of the antiangiogenic factor tissue inhibitor of metalloproteinase-1 and anti-inflammatory cytokine interleukin-10 were increased. EC-SOD decreased new vessel formation, epidermal edema, and inflammatory cell infiltration in UVB-irradiated transgenic mice. Moreover, cells treated with recombinant human EC-SOD showed inhibited endothelial tube formation and cell proliferation. Overall, the antiangiogenic and anti-inflammatory effects of EC-SOD might be due to suppression of hypoxia-inducible factor-1α, protein kinase C, and nuclear factor-κB expression. Furthermore, EC-SOD expression in tissue from psoriasis patients was markedly decreased in psoriatic lesional and nonlesional skins from psoriasis patients in comparison to normal skin from healthy volunteers. Together, these results suggest that EC-SOD may provide a novel therapeutic approach to treating angiogenic and inflammatory skin diseases such as psoriasis.

Mitochondria-derived superoxide and voltage-gated sodium channels in baroreceptor neurons from chronic heart-failure rats

Our previous study has shown that chronic heart failure (CHF) reduces expression and activation of voltage-gated sodium (Na(v)) channels in baroreceptor neurons, which are involved in the blunted baroreceptor neuron excitability and contribute to the impairment of baroreflex in the CHF state. The present study examined the role of mitochondria-derived superoxide in the reduced Na(v) channel function in coronary artery ligation-induced CHF rats. CHF decreased the protein expression and activity of mitochondrial complex enzymes and manganese SOD (MnSOD) and elevated the mitochondria-derived superoxide level in the nodose neurons compared with those in sham nodose neurons. Adenoviral MnSOD (Ad.MnSOD) gene transfection (50 multiplicity of infection) into the nodose neurons normalized the MnSOD expression and reduced the elevation of mitochondrial superoxide in the nodose neurons from CHF rats. Ad.MnSOD also partially reversed the reduced protein expression and current density of the Na(v) channels and the suppressed cell excitability (the number of action potential and the current threshold for inducing action potential) in aortic baroreceptor neurons from CHF rats. Data from the present study indicate that mitochondrial dysfunction, including decreased protein expression and activity of mitochondrial complex enzymes and MnSOD and elevated mitochondria-derived superoxide, contributes to the reduced Na(v) channel activation and cell excitability in the aortic baroreceptor neurons in CHF rats.

Cytoplasmic superoxide causes bone fragility owing to low-turnover osteoporosis and impaired collagen cross-linking

The aging process correlates with the accumulation of cellular and tissue damage caused by oxidative stress. Although previous studies have suggested that oxidative stress plays a pathologic role in the development of bone fragility, little direct evidence has been found. In order to investigate the pathologic significance of oxidative stress in bones, we analyzed the bone tissue of mice deficient in cytoplasmic copper/zinc superoxide dismutase (CuZn-SOD, encoded by the Sod1 gene; Sod1(-/-)). In this study, we showed for the first time that in vivo cytoplasmic superoxide caused a distinct weakness in bone stiffness and decreased BMD, aging-like changes in collagen cross-linking, and transcriptional alterations in the genes associated with osteogenesis. We also showed that the surface areas of osteoblasts and osteoclasts were decreased significantly in the lumbar vertebrae of Sod1(-/-) mice, indicating the occurrence of low-turnover osteopenia. In vitro experiments demonstrated that intracellular oxidative stress induced cell death and reduced the proliferation in primary osteoblasts but not in osteoclasts, indicating that impaired osteoblast viability caused the decrease in osteoblast number and suppressed RANKL/M-CSF osteoclastogenic signaling in bone. Furthermore, treatment with an antioxidant, vitamin C, effectively improved bone fragility and osteoblastic survival. These results imply that intracellular redox imbalance caused by SOD1 deficiency plays a pivotal role in the development and progression of bone fragility both in vivo and in vitro. We herein present a valuable model for investigating the effects of oxidative stress on bone fragility in order to develop suitable therapeutic interventions.

Extracellular superoxide dismutase in macrophages augments bacterial killing by promoting phagocytosis

Extracellular superoxide dismutase (EC-SOD) is abundant in the lung and limits inflammation and injury in response to many pulmonary insults. To test the hypothesis that EC-SOD has an important role in bacterial infections, wild-type and EC-SOD knockout (KO) mice were infected with Escherichia coli to induce pneumonia. Although mice in the EC-SOD KO group demonstrated greater pulmonary inflammation than did wild-type mice, there was less clearance of bacteria from their lungs after infection. Macrophages and neutrophils express EC-SOD; however, its function and subcellular localization in these inflammatory cells is unclear. In the present study, immunogold electron microscopy revealed EC-SOD in membrane-bound vesicles of phagocytes. These findings suggest that inflammatory cell EC-SOD may have a role in antibacterial defense. To test this hypothesis, phagocytes from wild-type and EC-SOD KO mice were evaluated. Although macrophages lacking EC-SOD produced more reactive oxygen species than did cells expressing EC-SOD after stimulation, they demonstrated significantly impaired phagocytosis and killing of bacteria. Overall, this suggests that EC-SOD facilitates clearance of bacteria and limits inflammation in response to infection by promoting bacterial phagocytosis.

Boswellic acids extract attenuates pulmonary fibrosis induced by bleomycin and oxidative stress from gamma irradiation in rats

BACKGROUND

Interstitial pulmonary fibrosis is characterized by an altered cellular composition of the alveolar region with excessive deposition of collagen. Lung inflammation is also common in pulmonary fibrosis. This study aims to test the inhibition of 5-lipooxygenase (5-LOX) by boswellic acid (BA) extract in an experimental model of pulmonary fibrosis using bleomycin (BL).

METHODS

Boswellic acid extract (1 g/kg) was force-fed to rats seven days prior to administration of BL or gamma irradiation or both. BL (0.15 U/rat) in 25 μl of 0.9% normal saline (NS) or 0.9% NS alone was administered intratracheally. Rats were exposed to two fractionated doses of gamma irradiation (0.5 Gy/dose/week) with a gamma cell-40 (Cesium-137 irradiation units, Canada) during the last two weeks of the experiment. BA was administered during BL or irradiation treatment or both. After the animals were sacrificed, bronchoalveolar lavage was performed; lungs were weighed and processed separately for biochemical and histological studies.

RESULTS

In rats treated with BL, levels of transforming growth factor-β1 (TGF-β1) and tumor necrosis factor-α (TNF-α) were significantly elevated (P = 0.05 and P = 0.005). Hydroxyproline was highly and extensively expressed. Immunoreactive compounds were abundantly expressed, represented in the levels of macrophages infiltrate, accumulation of eosinophils and neutrophils in the lung as well as the aggregation of fibroblasts in the fibrotic area. The levels of lipoxygenase enzyme activity were significantly increased (P = 0.005). Antioxidant activities measured in BL-treated rats deteriorated, coupled with the elevation of both levels of plasma lipid peroxide (LP) content and bronchoalveolar lavage lactate dehydrogenase activity. BA-treated rats had reduced number of macrophages, (P = 0.01), neutrophils in bronchoalveolar lavage (P = 0.01) and protein (P = 0.0001). Moreover, the hydroxyproline content was significantly lowered in BA-treated rats (P = 0.005). BA extract inhibited the TGF-ß induced fibrosis (P = 0.01) and 5-LOX activity levels (P = 0.005).Histologically, BA reduced the number of infiltrating cells, ameliorated the destruction of lung architecture and attenuated lung fibrosis.

CONCLUSION

BA attenuates the BL-induced injury response in rats, such as collagen accumulation, airway dysfunction and injury. This study suggests that the blocking of 5-LOX may prevent the progression of fibrosis.

Angiotensin II-NADPH oxidase-derived superoxide mediates diabetes-attenuated cell excitability of aortic baroreceptor neurons

Overactivation of hyperpolarization-activated cyclic nucleotide-gated (HCN) channels is involved in diabetes-depressed excitability of aortic baroreceptor neurons in nodose ganglia. This involvement links to the autonomic dysfunction associated with high morbidity and mortality in diabetic patients. The present study examined the effects of an angiotensin II type I receptor (AT(1)R) antagonist (losartan), a NADPH oxidase inhibitor (apocynin), and a superoxide dismutase mimetic (tempol) on the enhanced HCN currents and attenuated cell excitability in diabetic nodose neurons. In sham and streptozotocin-induced type 1 diabetic rats, HCN currents and cell excitability of aortic baroreceptor neurons were recorded by the whole cell patch-clamp technique. The angiotensin II level in nodose ganglia from diabetic rats was higher than that from sham rats (101.6 ± 4.8 vs. 38.9 ± 4.2 pg/mg protein, P < 0.05). Single-cell RT-PCR, Western blot, immunofluorescence staining, and chemiluminescence data showed that mRNA and protein expression of AT(1)R, protein expression of NADPH oxidase components, and superoxide production in nodose neurons were increased in diabetic rats compared with those from sham rats. HCN current density was higher and cell excitability was lower in aortic baroreceptor neurons from diabetic rats than that from sham rats. Losartan (1 μM), apocynin (100 μM), and tempol (1 mM) normalized the enhanced HCN current density and increased the cell excitability in the aortic baroreceptor neurons of diabetic rats. These findings suggest that endogenous angiotensin II-NADPH oxidase-superoxide signaling contributes to the enhanced HCN currents and the depressed cell excitation in the aortic baroreceptor neurons of diabetic rats.

Superoxide dismutases: role in redox signaling, vascular function, and diseases

Excessive reactive oxygen species Revised abstract, especially superoxide anion (O₂•-), play important roles in the pathogenesis of many cardiovascular diseases, including hypertension and atherosclerosis. Superoxide dismutases (SODs) are the major antioxidant defense systems against (O₂•-), which consist of three isoforms of SOD in mammals: the cytoplasmic Cu/ZnSOD (SOD1), the mitochondrial MnSOD (SOD2), and the extracellular Cu/ZnSOD (SOD3), all of which require catalytic metal (Cu or Mn) for their activation. Recent evidence suggests that in each subcellular location, SODs catalyze the conversion of (O₂•-), H2O2, which may participate in cell signaling. In addition, SODs play a critical role in inhibiting oxidative inactivation of nitric oxide, thereby preventing peroxynitrite formation and endothelial and mitochondrial dysfunction. The importance of each SOD isoform is further illustrated by studies from the use of genetically altered mice and viral-mediated gene transfer. Given the essential role of SODs in cardiovascular disease, the concept of antioxidant therapies, that is, reinforcement of endogenous antioxidant defenses to more effectively protect against oxidative stress, is of substantial interest. However, the clinical evidence remains controversial. In this review, we will update the role of each SOD in vascular biologies, physiologies, and pathophysiologies such as atherosclerosis, hypertension, and angiogenesis. Because of the importance of metal cofactors in the activity of SODs, we will also discuss how each SOD obtains catalytic metal in the active sites. Finally, we will discuss the development of future SOD-dependent therapeutic strategies.

Smoking and COPD increase sputum levels of extracellular superoxide dismutase

Extracellular superoxide dismutase (ECSOD) is the major superoxide-scavenging enzyme in the lung. Certain ECSOD polymorphisms are protective against COPD. We postulated that smokers and COPD subjects would have altered levels of ECSOD in the lung, airway secretions, and/or plasma. Lung tissue ECSOD was evaluated from nonsmokers, smokers, and subjects with mild to very severe COPD by Western blot, immunohistochemistry, and ELISA. ECSOD levels in plasma, bronchoalveolar lavage fluid (BALF), and induced-sputum supernatants were analyzed by ELISA and correlated with smoking history and disease status. Immunohistochemistry identified ECSOD in extracellular matrix around bronchioles, arteries, and alveolar walls, with decreases seen in the interstitium and vessels of severe COPD subjects using digital image analysis. Plasma ECSOD did not differ between COPD subjects and controls nor based on smoking status. ECSOD levels in induced sputum supernatants were elevated in current smokers and especially in COPD subjects compared to nonsmokers, whereas corresponding changes could not be seen in the BALF. ECSOD expression was reduced around vessels and bronchioles in COPD lungs. Substantial increases in sputum ECSOD in smokers and COPD is interpreted as an adaptive response to increased oxidative stress and may be a useful biomarker of disease activity in COPD.

Potent protection of gallic acid against DNA oxidation: results of human and animal experiments

Gallic acid (3,4,5-trihydroxybenzoic acid, GA) is a constituent of plant derived foods, beverages and herbal remedies. We investigated its DNA protective properties in a placebo controlled human intervention trial in single cell gel electrophoresis experiments. Supplementation of drinking water with GA (12.8 mg/person/d) for three days led to a significant reduction of DNA migration attributable to oxidised pyrimidines (endonuclease III sensitive sites) and oxidised purines (formamidopyrimidine glycosylase sensitive sites) in lymphocytes of healthy individuals by 75% and 64% respectively. Also DNA damage caused by treatment of the cells with reactive oxygen species (ROS) was reduced after GA consumption (by 41%). These effects were paralleled by an increase of the activities of antioxidant enzymes (superoxide dismutase, glutathione peroxidase and glutathion-S-transferase-π) and a decrease of intracellular ROS concentrations in lymphocytes, while no alterations of the total antioxidant capacity (TAC), of malondialdehyde levels in serum and of the urinary excretion of isoprostanes were found. Experiments with rats showed that GA reduces oxidatively damaged DNA in lymphocytes, liver, colon and lungs and protects these organs against γ-irradiation-induced strand breaks and formation of oxidatively damaged DNA-bases. Furthermore, the number of radiation-induced preneoplastic hepatic foci was decreased by 43% after oral administration of the phenolic. Since we did not find alterations of the TAC in plasma and lipid peroxidation of cell membranes but intracellular effects it is likely that the antioxidant properties of GA seen in vivo are not due to direct scavenging of radicals but rather to indirect mechanisms (e.g. protection against ROS via activation of transcription factors). As the amount of GA used in the intervention trial is similar to the daily intake in Middle Europe (18 mg/person/day), our findings indicate that it may contribute to prevention of formation of oxidatively damaged DNA in humans.

The effects of vitamin A supplementation to rats during gestation and lactation upon redox parameters: increased oxidative stress and redox modulation in mothers and their offspring

Vitamin A is an essential nutrient required in adequate amounts for reproduction and development. Subtle variations in the status of maternal nutrition may affect physiological and metabolic parameters in the fetus. Evidence suggests a key role for oxidative stress in these events. Literature is controversial about the effects of vitamin A supplementation. Here, we studied the effects of vitamin A supplementation on female Wistar rats during gestation and lactation on oxidative stress parameters of maternal and offspring tissues. Rats received daily doses of vitamin A at 2500, 12,500 and 25,000IU/kg. We observed an increase of oxidative damage markers in the reproductive tissues and plasma of dams. The activity of glutathione-S-transferase was modulated by vitamin A supplementation. It was found to be increased in the liver of dams and decreased in the kidneys of mothers and offspring. In pups, supplementation decreased the total antioxidant potential of the liver along with decreased superoxide dismutase/catalase activity ratio in the kidney. The levels of lipoperoxidation were increased in male offspring, but decreased in female pups. Collectively, the results suggest that excessive vitamin A intake during gestation and lactation might be toxic for mothers with adverse effects for the developing offspring.

Exacerbated pulmonary arterial hypertension and right ventricular hypertrophy in animals with loss of function of extracellular superoxide dismutase

Studies have demonstrated that increased oxidative stress contributes to the pathogenesis and the development of pulmonary artery hypertension (PAH). Extracellular superoxide dismutase (SOD3) is essential for removing extracellular superoxide anions, and it is highly expressed in lung tissue. However, it is not clear whether endogenous SOD3 can influence the development of PAH. Here we examined the effect of SOD3 knockout on hypoxia-induced PAH in mice and a loss-of-function SOD3 gene mutation (SOD3(E124D)) on monocrotaline (40 mg/kg)-induced PAH in rats. SOD3 knockout significantly exacerbated 2 weeks of hypoxia-induced right ventricular (RV) pressure and RV hypertrophy, whereas RV pressure in SOD3 knockout mice under normoxic conditions is similar to wild-type controls. In untreated control rats at age of 8 weeks, there was no significant difference between wild-type and SOD3(E124D) rats in RV pressure and the ratio of RV weight:left ventricular weight (0.25±0.02 in wild-type rats versus 0.25±0.01 in SOD3(E124D) rats). However, monocrotaline caused significantly greater increases of RV pressure in SOD3(E124D) rats (48.6±1.8 mm Hg in wild-type versus 57.5±3.1 mm Hg in SOD3(E124D) rats), of the ratio of RV weight:left ventricular weight (0.41±0.01 versus 0.50±0.09; P<0.05), and of the percentage of fully muscularized small arterioles in SOD3(E124D) rats (55.2±2.3% versus 69.9±2.6%; P<0.05). Together, these findings indicate that the endogenous SOD3 has no role in the development of PAH under control conditions but plays an important role in protecting the lung from the development of PAH under stress conditions.

Antioxidative Enzyme Activities and Lipid Peroxidation in Children with Inflammatory Endothelial Injury

During the inflammatory process endothelial cells are activated and a proadherent ability is assumed. The synthesis of reactive oxygen metabolites, which follows the immunological processes, can cause oxidative damage to endothelial cells leading to the clinical expression of disease including a variety of skin manifestations. In this study the activity of antioxidant enzymes (superoxide dismutase, catalase, glutathione peroxidase) and the malondialdehyde concentration were examined in 36 children with inflammation-mediated damage to microvascular endothelial cells. On the basis of clinical manifestations the studied children were divided into 4 groups (1st group-macular skin manifestations, 2nd group-maculo-papular skin manifestations, 3rd group-papular skin manifestations, 4th group- erythematous skin manifestations). All the examined children showed symptoms of inflammation (mainly respiratory tract infections) with leukocytosis and monocytosis before actual skin manifestations took place. Superoxide dismutase activity was significantly decreased in three groups of patients, except in the group with erythematous skin manifestations. Catalase activity was significantly increased in all the groups compared to the control group. The values of malondialdehyde were significantly increased in the groups of children with maculo-papular and erythematous skin manifestations. The results have confirmed the presence of a changed antioxidant enzyme pattern indicating oxidative stress during inflammatory endothelial cells injury. Malondialdehyde was not an adequate parameter in its evaluation.

Molecular characterization and oxidative stress response of an intracellular Cu/Zn superoxide dismutase (CuZnSOD) of the whitefly, Bemisia tabaci

Superoxide dismutases (SODs) are important for the survival of insects under environmental and biological stresses; however, little attention has been devoted to the functional characterization of SODs in whitefly. In this study, an intracellular copper/zinc superoxide dismutase of whitefly (Bemisia tabaci) (Bt-CuZnSOD) was cloned. Sequence analysis indicated that the full length cDNA of Bt-CuZnSOD is of 907 bp with a 471 bp open reading frame encoding 157 amino acids. The deduced amino acid sequence shares common consensus patterns with the CuZnSODs of various vertebrate and invertebrate animals. Phylogenetic analysis revealed that Bt-CuZnSOD is grouped together with intracellular CuZnSODs. Bt-CuZnSOD was then over-expressed in E. coli and purified using GST purification system. The enzymatic activity of purified Bt-CuZnSOD was assayed under various temperatures. When whiteflies were exposed to low (4°C) and high (40°C) temperatures, the in vivo activity of Bt-CuZnSOD was significantly increased. Furthermore, we measured the activities of several antioxidant enzymes, including SOD, catalase and peroxidase, in the whitefly after transferring the whitefly from cotton to tobacco (an unfavorable host plant). We found that the activity of SOD increased rapidly on tobacco plant. Taken together, these results suggest that the Bt-CuZnSOD plays a major role in protecting the whitefly against various stress conditions.

Towards Al3+-Induced Manganese-Containing Superoxide Dismutase Inactivation and Conformational Changes: An Integrating Study with Docking Simulations

Superoxide dismutase (SOD, EC 1.15.1.1) plays an important antioxidant defense role in skins exposed to oxygen. We studied the inhibitory effects of Al³⁺ on the activity and conformation of manganese-containing SOD (Mn-SOD). Mn-SOD was significantly inactivated by Al³⁺ in a dose-dependent manner. The kinetic studies showed that Al³⁺ inactivated Mn-SOD follows the first-order reaction. Al³⁺ increased the degree of secondary structure of Mn-SOD and also disrupted the tertiary structure of Mn-SOD, which directly resulted in enzyme inactivation. We further simulated the docking between Mn-SOD and Al³⁺ (binding energy for Dock 6.3: −14.07 kcal/mol) and suggested that ASP152 and GLU157 residues were predicted to interact with Al³⁺, which are not located in the Mn-contained active site. Our results provide insight into the inactivation of Mn-SOD during unfolding in the presence of Al³⁺ and allow us to describe a ligand binding via inhibition kinetics combined with the computational prediction.

Allele-specific effects of ecSOD on asbestos-induced fibroproliferative lung disease in mice

Previous work by others suggests that there is a strain-dependent variation in the susceptibility to inflammatory lung injury in mice. Specifically, the 129/J mice appear to be more resistant to asbestos-induced pulmonary fibrosis than the C57BL/6 strain. A separate line of evidence suggests that extracellular superoxide dismutase (ecSOD) may play an important role in protecting the lung from such injuries. We have recently reported that the 129/J strain of mice has an ecSOD genotype and phenotype distinctly different from those of the C57BL/6 mice. In order to identify ecSOD as a potential "asbestos-injury resistance" gene, we bred congenic mice, on the C57BL/6 background, carrying the wild type (sod3wt) or the 129/J (sod3129) allele for ecSOD. This allowed us to examine the role of ecSOD polymorphism in susceptibility to lung injury in an otherwise identical genetic background. Interestingly, asbestos treatment induces a significant (~40%) increase in plasma ecSOD activity in the sod3129 mice, but not in the sod3wt mice. Asbestos administration results in a loss of ecSOD activity and protein from lung tissue of both congenic strains, but the lung ecSOD activity remains significantly higher in sod3129 mice. As expected, asbestos treatment results in a significant recovery of ecSOD protein in bronchoalveolar lavage fluid (BALF). The BALF of sod3129 mice also have significantly lower levels of proteins and inflammatory cells, especially neutrophils, accompanied by a significantly lower extent of lung injury, as measured by a pathology index score or hydroxyproline content. Immunohistochemistry reveals a significant loss of ecSOD from the tips of the respiratory epithelial cells in response to asbestos treatment and that the loss of immunodetectable ecSOD is compensated for by enzyme expression by infiltrating cells, especially in the sod3wt mice. Our studies thus identify ecSOD as an important anti-inflammatory gene, responsible for most, if not all of the resistance to asbestos-induced lung injury reported for the 129/J strain of mice. The data further suggest allele-specific differences in the regulation of ecSOD expression. These congenic mice therefore represent a very useful model to study the role of this enzyme in all inflammatory diseases. Polymorphisms in human ecSOD have also been reported and it appears logical to assume that such variations may have a profound effect on disease susceptibility.

Extracellular superoxide dismutase protects cardiovascular syndecan-1 from oxidative shedding

The extracellular matrix is a complex system that regulates cell function within a tissue. The antioxidant enzyme extracellular superoxide dismutase (EC-SOD) is bound to the matrix, and previous studies show that a lack of EC-SOD results in increased cardiac injury, fibrosis, and loss of cardiac function. This study tests the hypothesis that EC-SOD protects against cardiac fibrosis mechanistically by limiting oxidative stress and oxidant-induced shedding of syndecan-1 in the extracellular matrix. Wild-type and EC-SOD null mice were treated with a single dose of doxorubicin, 15 mg/kg, and evaluated on day 15. Serum and left-ventricle tissue were collected for biochemical assays, including Western blot, mRNA expression, and immunohistochemical staining for syndecan-1. The loss of EC-SOD and doxorubicin-induced oxidative injury led to increases in shed syndecan-1 in the serum, which originates from the endothelium of the vasculature. The shed syndecan-1 ectodomain induces proliferation of primary mouse cardiac fibroblasts. This study suggests that one mechanism by which EC-SOD protects the heart against cardiac fibrosis is the prevention of oxidative shedding of cardiovascular syndecan-1 and its subsequent induction of fibroblast proliferation. This study provides potential new targets for understanding and altering fibrosis progression in the heart.

Simulation of generation-collection experiments with homogeneous kinetics: application to electrochemical investigation of superoxide radical anion generation by osteoclasts on bone

We report simulations of electrochemical generation-collection experiments in which the generator is a small disc producing a specified time-dependent flux of the analyte and the collector is a large planar electrode which collects the analyte at the mass transport-controlled rate. This geometry corresponds to many experiments in bioelectrochemistry where a relatively large sensor is used to detect the products of a cell's metabolism at low concentration. In particular, our simulations are motivated by attempts to understand our results on the detection of the superoxide radical anion burst generated by osteoclasts (bone-resorbing cells) in response to various stimuli. Superoxide is present at low levels and disproportionates in aqueous media; however, the homogeneous kinetics are included in our simulations and the results show that it is possible to estimate the magnitude of the flux of superoxide produced by the cells and to accurately determine the time-dependence of the flux in response to stimuli such as injection of parathyroid hormone, vitamin D(3) and pertussis toxin. In all these cases, the superoxide anion flux was successfully modeled as uniform across the cell surface with time-dependence of the form j(0)e(-k(d)t) + j(∞). j(∞) is the sustained flux of superoxide and the first-order rate constant k(d) and the magnitude j(0) describe the transient component of the flux. The simulations indicate that for cell-electrode gaps D approximately < √(D/k(d)), where D is the diffusion coefficient, the value of k(d) can be accurately extracted from the time-dependence of the collector current without detailed knowledge of parameters which are hard to measure during the experiment, e.g., the cell radius a and cell-electrode separation d. In the case of parathyroid hormone, the first-order rate constant describing the decay of the transient component was k(d) = 1.8 ± 0.8 × 10(-1) s(-1), but much slower decays were observed in response to pertussis toxin (k(d) = 1.5 ± 0.5 × 10(-2) s(-1)) and vitamin D(3) (k(d) = 1.1 ± 0.5 × 10(-3) s(-1)).

Air pollution and circulating biomarkers of oxidative stress

Chemical components of air pollutant exposures that induce oxidative stress and subsequent inflammation may be partly responsible for associations of cardiovascular morbidity and mortality with airborne particulate matter and combustion-related pollutant gasses. However, epidemiologic evidence regarding this is limited. An exposure-assessment approach is to measure the oxidative potential of particle mixtures because it is likely that hundreds of correlated chemicals are involved in overall effects of air pollution on health. Oxidative potential likely depends on particle composition and size distribution, especially ultrafine particle concentration, and on transition metals and certain semivolatile and volatile organic chemicals. For health effects, measuring systemic oxidative stress in the blood is one feasible approach, but there is no universal biomarker of oxidative stress and there are many potential target molecules (lipids, proteins, DNA, nitric oxide, etc.), which may be more or less suitable for specific study goals. Concurrent with the measurement of oxidative stress, it is important to measure gene and/or protein expression of endogenous antioxidant enzymes because they can modify relations between oxidative stress biomarkers and air pollutants. Conversely, the expression and activities of these enzymes are modified by oxidative stress. This interplay will likely determine the observed effects of air pollutants on systemic inflammatory and thrombotic mediators and related clinical outcomes. Studies are needed to assess the reliability and validity of oxidative stress biomarkers, evaluate differences in associations between oxidative stress biomarkers and various pollutant measurements (mass, chemical components, and oxidative potential), and evaluate impacts of antioxidant responses on these relations.

Zinc-metallothionein: a potential mediator of antioxidant defence mechanisms in response to dopamine-induced stress

Clinically, Parkinson's disease (PD) is a neurodegenerative disorder characterized by the development of tremors and rigidity that is found primarily in patients over the age of 50. At the cellular level, it is clear that the pathology of PD results from the progressive loss of dopaminergic neurons in the substantia nigra. Several lines of evidence have implicated oxidative stress as a contributing factor to the depletion of dopaminergic neurons in PD. Under conditions of oxidative stress, the neurotransmitter dopamine can be oxidized to form neurotoxic quinone and semiquinone products. While dopaquinones are known to be extremely reactive towards sulfhydryl groups of many cellular substrates, mounting evidence suggests that their toxic effects can be quenched by intrinsic antioxidant mechanisms (e.g., glutathione). However, to respond appropriately to differing levels of oxidative stress, cells require a mechanism to regulate an appropriate response. This manuscript proposes metallothionein as a major cellular sensor of oxidized dopamine stress and metallothionein-mediated Zn2+ mobilization as an effecter signal that is used by the cell to manage oxidized dopamine as an intrinsic neurotoxin.

The effects of aging on pulmonary oxidative damage, protein nitration, and extracellular superoxide dismutase down-regulation during systemic inflammation

Systemic inflammatory response syndrome (SIRS), a serious clinical condition characterized by whole-body inflammation, is particularly threatening for elderly patients, who suffer much higher mortality rates than the young. A major pathological consequence of SIRS is acute lung injury caused by neutrophil-mediated oxidative damage. Previously, we reported an increase in protein tyrosine nitration (a marker of oxidative/nitrosative damage) and a decrease in the antioxidant enzyme extracellular superoxide dismutase (EC-SOD) in the lungs of young mice during endotoxemia-induced SIRS. Here we demonstrate that during endotoxemia, down-regulation of EC-SOD is significantly more profound and prolonged, whereas up-regulation of iNOS is augmented, in aged compared to young mice. Aged mice also showed 2.5-fold higher protein nitration levels, compared to young mice, with particularly strong nitration in the pulmonary vascular endothelium during SIRS. Additionally, by two-dimensional gel electrophoresis, Western blotting, and mass spectrometry, we identified proteins that show increased tyrosine nitration in age- and SIRS-dependent manners; these proteins (profilin-1, transgelin-2, LASP 1, tropomyosin, and myosin) include components of the actin cytoskeleton responsible for maintaining pulmonary vascular permeability. Reduced EC-SOD in combination with increased oxidative/nitrosative damage and altered cytoskeletal protein function due to tyrosine nitration may contribute to augmented lung injury in the aged with SIRS.