SOD3 decreases ischemic injury derived apoptosis through phosphorylation of Erk1/2, Akt, and FoxO3a

Angiogenic potential of skeletal muscle derived extracellular vesicles differs between oxidative and glycolytic muscle tissue in mice

Skeletal muscle fibers regulate surrounding endothelial cells (EC) via secretion of numerous angiogenic factors, including extracellular vesicles (SkM-EV). Muscle fibers are broadly classified as oxidative (OXI) or glycolytic (GLY) depending on their metabolic characteristics. OXI fibers secrete more pro-angiogenic factors and have greater capillary densities than GLY fibers. OXI muscle secretes more EV than GLY, however it is unknown whether muscle metabolic characteristics regulate EV contents and signaling potential. EVs were isolated from primarily oxidative or glycolytic muscle tissue from mice. MicroRNA (miR) contents were determined and endothelial cells were treated with OXI- and GLY-EV to investigate angiogenic signaling potential. There were considerable differences in miR contents between OXI- and GLY-EV and pathway analysis identified that OXI-EV miR were predicted to positively regulate multiple endothelial-specific pathways, compared to GLY-EV. OXI-EV improved in vitro angiogenesis, which may have been mediated through nitric oxide synthase (NOS) related pathways, as treatment of endothelial cells with a non-selective NOS inhibitor abolished the angiogenic benefits of OXI-EV. This is the first report to show widespread differences in miR contents between SkM-EV isolated from metabolically different muscle tissue and the first to demonstrate that oxidative muscle tissue secretes EV with greater angiogenic signaling potential than glycolytic muscle tissue.

Differential expression patterns of genes associated with metabolisms, muscle growth and repair in Pectoralis major muscles of fast- and medium-growing chickens

The aim of this study was to investigate the expression of genes related to muscle growth, hypoxia and oxidative stress responses, a multi-substrate serine/threonine-protein kinase (AMPK) and AMPK-related kinases, carbohydrate metabolism, satellite cells activities and fibro- adipogenic progenitors (FAPs) in fast-growing (FG) (n = 30) and medium-growing (MG) chickens (n = 30). Pectoralis major muscles were collected at 7d, 14d, 21d, 28d, 35d and 42d of age. According to their macroscopic features, the samples from FG up to 21d of age were classified as unaffected, while all samples collected at an older age exhibited macroscopic features ascribable to white striping and/or wooden breast abnormalities. In contrast, MG samples did not show any feature associated to muscle disorders. The absolute transcript abundance of 33 target genes was examined by droplet digital polymerase chain reaction. The results showed differential gene expression profiles between FG and MG chickens at different ages. While most genes remained unchanged in MG chickens, the expression patterns of several genes in FG were significantly affected by age. Genes encoding alpha 1, alpha 2, beta 2 and gamma 3 isoforms of AMPK, as well as AMPK-related kinases, were identified as differentially expressed between the two strains. The results support the hypothesis of oxidative stress-induced muscle damage with metabolic alterations in FG chickens. An increased expression of ANXA2, DES, LITAF, MMP14, MYF5 and TGFB1 was observed in FG strain. The results suggest the occurrence of dysregulation of FAP proliferation and differentiation occurring during muscle repair. FAPs could play an important role in defining the proliferation of connective tissue (fibrosis) and deposition of intermuscular adipose tissue which represents distinctive traits of muscle abnormalities. Overall, these findings demonstrate that dysregulated molecular processes associated with myopathic lesions in chickens are strongly influenced by growth rate, and, to some extent, by age.

Combined action of FOXO1 and superoxide dismutase 3 promotes MDA-MB-231 cell migration

Superoxide dismutase 3 (SOD3), one of SOD isozymes, maintains extracellular redox homeostasis through the dismutation reaction of superoxide. Loss of SOD3 in tumor cells induces oxidative stress and exacerbates tumor progression; however, interestingly, overexpression of SOD3 also promotes cell proliferation through the production of hydrogen peroxide. In this study, we investigated the functional role of SOD3 in human breast cancer MDA-MB-231 cell migration and the molecular mechanisms involved in high expression of SOD3 in MDA-MB-231 cells and human monocytic THP-1 cells. The level of histone H3 trimethylation at lysine 27 (H3K27me3), a marker of gene silencing, was decreased in 12-O-tetra-decanoylphorbol-13-acetate (TPA)-treated THP-1 cells. Also, that reduction was observed within the SOD3 promoter region. We then investigated the involvement of H3K27 demethylase JMJD3 in SOD3 induction. The induction of SOD3 and the reduction of H3K27me3 were inhibited in the presence of JMJD3 inhibitor, GSK-J4. Additionally, it was first determined that the knockdown of the transcription factor forkhead box O1 (FOXO1) significantly suppressed TPA-elicited SOD3 induction. FOXO1-mediated SOD3 downregulation was also observed in MDA-MB-231 cells, and knockdown of FOXO1 and SOD3 suppressed cell migration. Our results provide a novel insight into epigenetic regulation of SOD3 expression in tumor-associated cells, and high expression of FOXO1 and SOD3 would participate in the migration of MDA-MB-231 cells.

Protective Effect of Calcium Dobesilate on Induced AKI in Severely Burned Mice

BACKGROUND

Early acute kidney injury (AKI) predicts a high mortality rate in severely burned patients. However, the pathophysiology of early AKI induced by severe burn has not been well-defined. This study was designed to examine the protective effects of calcium dobesilate (CaD) against severe burn-induced early AKI in mice and explore the mechanism.

METHODS

The shaved backs of mice were immersed in 100°C water for 10 s to make severe burn (40% of the total body surface area). CD-57 male mice were randomly divided into sham, burn, burn + vehicle, and burn + CaD groups. Renal function, reactive oxygen species generation, tubular necrosis, and phosphorylation of mitogen-activated protein kinase, protein kinase B (Akt), and nuclear factor (NF)-κB were measured at 24 and 48 h after the burn. Renal histology, ELISA, qRT-PCR, and Western blotting were performed on the renal tissue of mice to examine the effects and mechanisms at 24 and 48 h after the burn.

RESULTS

Tubular damage, cast formation, and elevations of serum creatinine, BUN, and renal tissue kidney injury molecule 1 levels were all observed in the burned mice, and these were all alleviated in the mice with CaD treatment. In addition, the levels of oxidation-reduction potential and malondialdehyde were decreased, while the activities of the endogenous antioxidative enzymes were increased in the kidney tissues from the mice after CaD treatment. Furthermore, the activities of Akt, p38, extracellular sign-regulated kinase, Jun N-terminal kinase, and NF-κB signaling were increased in the kidney of burned mice and normalized after CaD treatment.

CONCLUSION

This study has established, for the first time, the protective effect of CaD against early AKI in severely burned mice. CaD may exert its protective effect through alleviating oxidative stress, apoptosis, and inflammation, as well as modulating some signaling pathways in the kidney.

Mesenchymal Stem Cell-Secreted Exosome Promotes Chemoresistance in Breast Cancer via Enhancing miR-21-5p-Mediated S100A6 Expression

Emerging evidence has shown the role of mesenchymal stem cell-derived exosome (MSC-exo) in inducing resistance of cancer cells to chemotherapy. However, it remains unclear whether the change of MSC-exo in response to chemotherapy also contributes to chemoresistance. In this study, we investigated the effect of a standard-of-care chemotherapeutic agent, doxorubicin (Dox), on MSC-exo and its contribution to the development of Dox resistance in breast cancer cells (BCs). We found that the exosome secreted by Dox-treated MSCs (Dt-MSC-exo) induced a higher degree of Dox resistance in BCs when compared with non-treated MSC-exo. By analysis of the MSC-exo-induced transcriptome change in BCs, we identified S100A6, a chemoresistant gene, as a top-ranked gene induced by MSC-exo in BCs, which was further enhanced by Dt-MSC-exo. Furthermore, we found that Dox induced the expression of miR-21-5p in MSCs and MSC-exo, which was required for the expression of S100A6 in BCs. Importantly, silencing of miR-21-5p expression in MSCs and MSC-exo abolished the resistance of BCs to Dox, indicating an exosomal miR-21-5p-regulated S100A6 in chemoresistance. Our study thus uncovered a novel mechanistic insight into the role of MSC-secreted exosome in the development of chemoresistance in the tumor microenvironment.

Excessive Reactive Oxygen Species Inhibit IL-17A+ γδ T Cells and Innate Cellular Responses to Bacterial Lung Infection

Aims: Excessive reactive oxygen species (ROS) are detrimental to immune cellular functions that control pathogenic microbes; however, the mechanisms are poorly understood. Our aim was to determine the immunological consequences of increased ROS levels during acute bacterial infection. Results: We used a model of Streptococcus pneumoniae (Spn) lung infection and superoxide dismutase 3-deficient (SOD3^-/-) mice, as SOD3 is a major antioxidant enzyme that catalyses the dismutation of superoxide radicals. First, we observed that in vitro, macrophages from SOD3^-/- mice generated excessive phagosomal ROS during acute bacterial infection. In vivo, there was a significant reduction in infiltrating neutrophils in the bronchoalveolar lavage fluid and reduced peribronchial and alveoli inflammation in SOD3^-/- mice 2 days after Spn infection. Annexin V/propidium iodide staining revealed enhanced apoptosis in neutrophils from Spn-infected SOD3^-/- mice. In addition, SOD3^-/- mice showed an altered macrophage phenotypic profile, with markedly diminished recruitment of monocytes (CD11c^lo, CD11b^hi) in the airways. Further investigation revealed significantly lower levels of the monocyte chemokine CCL-2, and cytokines IL-23, IL-1β, and IL-17A in Spn-infected SOD3^-/- mice. There were also significantly fewer IL-17A-expressing gamma-delta T cells (γδ T cells) in the lungs of Spn-infected SOD3^-/- mice. Innovation: Our data demonstrate that SOD3 deficiency leads to an accumulation of phagosomal ROS levels that initiate early neutrophil apoptosis during pneumococcal infection. Consequent to these events, there was a failure to initiate innate γδ T cell responses. Conclusion: These studies offer new cellular and mechanistic insights into how excessive ROS can regulate innate immune responses to bacterial infection.

Carcinogenesis and Reactive Oxygen Species Signaling: Interaction of the NADPH Oxidase NOX1-5 and Superoxide Dismutase 1-3 Signal Transduction Pathways

SIGNIFICANCE

Reduction/oxidation (redox) balance could be defined as an even distribution of reduction and oxidation complementary processes and their reaction end products. There is a consensus that aberrant levels of reactive oxygen species (ROS), commonly observed in cancer, stimulate primary cell immortalization and progression of carcinogenesis. However, the mechanism how different ROS regulate redox balance is not completely understood. Recent Advances: In the current review, we have summarized the main signaling cascades inducing NADPH oxidase NOX1-5 and superoxide dismutase (SOD) 1-3 expression and their connection to cell proliferation, immortalization, transformation, and CD34+ cell differentiation in thyroid, colon, lung, breast, and hematological cancers.

CRITICAL ISSUES

Interestingly, many of the signaling pathways activating redox enzymes or mediating the effect of ROS are common, such as pathways initiated from G protein-coupled receptors and tyrosine kinase receptors involving protein kinase A, phospholipase C, calcium, and small GTPase signaling molecules.

FUTURE DIRECTIONS

The clarification of interaction of signal transduction pathways could explain how cells regulate redox balance and may even provide means to inhibit the accumulation of harmful levels of ROS in human pathologies.

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

AIMS

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

RESULTS

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

INNOVATION

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

CONCLUSIONS

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

Inhibitory effects of superoxide dismutase 3 on Propionibacterium acnes-induced skin inflammation

Propionibacterium acnes is a well-known commensal bacterium that plays an important role in the pathogenesis of acne and chronic inflammatory skin disease. In this study, we investigated the effect of superoxide dismutase 3 (SOD3) on P. acnes- or peptidoglycan (PGN)-induced inflammation in vitro and in vivo. Our data demonstrated that SOD3 suppressed toll-like receptor-2 (TLR-2) expression in P. acnes- or PGN-treated keratinocytes and sebocytes. Moreover, we found that SOD3 suppressed the expressions of phosphorylated nuclear factor-κB (NF-κB) and p38 in P. acnes- or PGN-treated cells. SOD3 also exhibited an anti-inflammatory role by reducing the expression of inflammasome-related proteins (NLRP3, ASC, caspase-1) and inhibiting the expression of pro-inflammatory cytokines, including tumor necrosis factor-α, interleukin-1β, interleukin-6, and interleukin-8. In addition, SOD3 reduced lipid accumulation and expression of lipogenic regulators in P. acnes-treated sebocytes. Recombinant SOD3-treated wild-type mice and SOD3 transgenic mice, which were subcutaneously infected with P. acnes, showed tolerance to inflammation through reducing inflammatory cell infiltration in skin, ear thickness, and expression of inflammatory mediators. Our result showed that SOD3 could suppress the inflammation through inhibition of TLR2/p38/NF-κB axis and NLRP3 inflammasome activation. Therefore, SOD3 could be a promising candidate for treatment of P. acnes-mediated skin inflammation.

The extracellular isoform of superoxide dismutase has a significant impact on cardiovascular ischaemia and reperfusion injury during cardiopulmonary bypass

OBJECTIVES

Cardiac surgery with cardiopulmonary bypass (CPB) provokes ischaemia and reperfusion injury (IRI). Superoxide is a main mediator of IRI and is detoxified by superoxide dismutases (SODs). Extracellular SOD (SOD3) is the prevailing isoform in the cardiovascular system. Its mutation is associated with elevated risk for ischaemic heart disease as epidemiological and experimental studies suggest. We investigated the influence of SOD3 on IRI in the context of CPB and hypothesized a protective role for this enzyme.

METHODS

Mutant rats with loss of SOD3 function induced by amino acid shift, SOD3-E124D, (SOD3 mutant; n = 9) were examined in a model of CPB with deep hypothermic circulatory arrest provoking global IRI and compared with SOD3 competent controls (n = 8) as well as sham animals (n = 7). SOD3 plasma activity was photometrically measured with a diazo dye-forming reagent. Activation of cardioprotective rescue pathways (p44-42 MAPK and STAT3), cleavage of PARP-1, expression of SOD isoforms (SOD1, 2 and 3) and nitric oxide metabolism were analysed on the protein level by western blot. To evaluate whether SOD3 inactivity directly affects the myocardium, we isolated adult cardiac myocytes, which underwent hypoxia prior to protein analyses.

RESULTS

Relative SOD3 plasma activity in SOD3 mutant rats was significantly decreased by at least 50% compared with that in SOD3 competent controls (prior to euthanasia P = 0.008). Effectively, physiological parameters [heart rate and mean arterial pressure (MAP)] indicated a trend toward impaired handling of ischaemia and reperfusion in SOD3 mutants: after reperfusion, mean heart rate was 46 bpm lower (P = 0.083) and MAP 8 mmHg lower (P = 0.288) than that in SOD competent controls. Decreased SOD3 activity led to reduced activation of cardioprotective rescue pathways in vivo and in vitro: relative activation of p44-42 MAPK (P = 0.074) and STAT3 (P = 0.027) was more than 30% decreased in heart and aortic tissue of SOD3 mutants (activity normalized to sham control as 1). After CPB, cleavage of PARP-1 was doubled in the control group (P = 0.017), but increased 3-fold in SOD3 mutants (P = 0.002). Furthermore, 3-nitrotyrosine as a measure of decreased nitric oxide bioavailability and other SOD isoforms (SOD1 and 2) were increased.

CONCLUSIONS

Collectively, SOD3 has a significant cardioprotective role in cases of IRI and directly affects the myocardium as hypothesized. Exploration of intervention strategies targeting SOD3 may provide therapeutic options against IRI and associated systemic inflammation.

Cardioprotective effects of combined therapy with diltiazem and superoxide dismutase on myocardial ischemia-reperfusion injury in rats

AIMS

Our experiments were designed to study the effect of diltiazem (DIL) combined with superoxide dismutase (SOD) on myocardial ischemia-reperfusion (MIRI) injury in a rat model.

MAIN METHODS

Fifty rats were randomly separated into sham, ischemia-reperfusion (IR), DIL (5mg/kg), SOD (10,000U/kg) and combinatorial therapy (DIL plus SOD) groups. MIRI was induced by ligating the left anterior descending coronary artery for 30min and then reperfusing for 60min. The cardioprotective effects of combinatorial therapy were evaluated using hemodynamics, biochemical indices, histopathology and apoptotic-related proteins and gene expression.

KEY FINDINGS

Compared with the IR group, combinatorial therapy significantly improved cardiac function and decreased arrhythmia, myocardial infarction area and release of myocardial enzyme. In addition, combinatorial therapy protected the myocardial cell structure as well as markedly alleviated oxidative stress, resulting in upregulation of Bcl-2 and adenine nucleotide transporter-1 expression as well as downregulation of Bax, caspase-3 and cleaved caspase-3 expression.

SIGNIFICANCE

Our results indicated that DIL combined with SOD can provide protection against MIRI in rats, and these effects may be attributed to a reduction in oxygen stress damage, attenuation of calcium overload, and inhibition of cell apoptosis.

Extracellular Superoxide Dismutase Expression in Papillary Thyroid Cancer Mesenchymal Stem/Stromal Cells Modulates Cancer Cell Growth and Migration

Tumor stroma-secreted growth factors, cytokines, and reactive oxygen species (ROS) influence tumor development from early stages to the metastasis phase. Previous studies have demonstrated downregulation of ROS-producing extracellular superoxide dismutase (SOD3) in thyroid cancer cell lines although according to recent data, the expression of SOD3 at physiological levels stimulates normal and cancer cell proliferation. Therefore, to analyze the expression of SOD3 in tumor stroma, we characterized stromal cells from the thyroid. We report mutually exclusive desmoplasia and inflammation in papillary and follicular thyroid cancers and the presence of multipotent mesenchymal stem/stromal cells (MSCs) in non-carcinogenic thyroids and papillary thyroid cancer (PTC). The phenotypic and differentiation characteristics of Thyroid MSCs and PTC MSCs were comparable with bone marrow MSCs. A molecular level analysis showed increased FIBROBLAST ACTIVATING PROTEIN, COLLAGEN 1 TYPE A1, TENASCIN, and SOD3 expression in PTC MSCs compared to Thyroid MSCs, suggesting the presence of MSCs with a fibrotic fingerprint in papillary thyroid cancer tumors and the autocrine-paracrine conversion of SOD3 expression, which was enhanced by cancer cells. Stromal SOD3 had a stimulatory effect on cancer cell growth and an inhibitory effect on cancer cell migration, thus indicating that SOD3 might be a novel player in thyroid tumor stroma.

Suppression of Neutrophil-Mediated Tissue Damage-A Novel Skill of Mesenchymal Stem Cells

Mesenchymal stem cells (MSCs) are crucial for tissue homeostasis and regeneration. Though of prime interest, their potentially protective role on neutrophil-induced tissue damage, associated with high morbidity and mortality, has not been explored in sufficient detail. Here we report the therapeutic skill of MSCs to suppress unrestrained neutrophil activation and to attenuate severe tissue damage in a murine immune-complex mediated vasculitis model of unbalanced neutrophil activation. MSC-mediated neutrophil suppression was due to intercellular adhesion molecule 1-dependent engulfment of neutrophils by MSCs, decreasing overall neutrophil numbers. Similar to MSCs in their endogenous niche of murine and human vasculitis, therapeutically injected MSCs via upregulation of the extracellular superoxide dismutase (SOD3), reduced super-oxide anion concentrations and consequently prevented neutrophil death, neutrophil extracellular trap formation and spillage of matrix degrading neutrophil elastase, gelatinase and myeloperoxidase. SOD3-silenced MSCs did not exert tissue protective effects. Thus, MSCs hold substantial therapeutic promise to counteract tissue damage in conditions with unrestrained neutrophil activation.

Extracellular Superoxide Dismutase: Growth Promoter or Tumor Suppressor?

Extracellular superoxide dismutase (SOD3) gene transfer to tissue damage results in increased healing, increased cell proliferation, decreased apoptosis, and decreased inflammatory cell infiltration. At molecular level, in vivo SOD3 overexpression reduces superoxide anion (O₂⁻) concentration and increases mitogen kinase activation suggesting that SOD3 could have life-supporting characteristics. The hypothesis is further strengthened by the observations showing significantly increased mortality in conditional knockout mice. However, in cancer SOD3 has been shown to either increase or decrease cell proliferation and survival depending on the model system used, indicating that SOD3-derived growth mechanisms are not completely understood. In this paper, the author reviews the main discoveries in SOD3-dependent growth regulation and signal transduction.

Extracellular superoxide dismutase deficiency impairs wound healing in advanced age by reducing neovascularization and fibroblast function

Advanced age is characterized by impairments in wound healing, and evidence is accumulating that this may be due in part to a concomitant increase in oxidative stress. Extended exposure to reactive oxygen species (ROS) is thought to lead to cellular dysfunction and organismal death via the destructive oxidation of intra-cellular proteins, lipids and nucleic acids. Extracellular superoxide dismutase (ecSOD/SOD3) is a prime antioxidant enzyme in the extracellular space that eliminates ROS. Here, we demonstrate that reduced SOD3 levels contribute to healing impairments in aged mice. These impairments include delayed wound closure, reduced neovascularization, impaired fibroblast proliferation and increased neutrophil recruitment. We further establish that SOD3 KO and aged fibroblasts both display reduced production of TGF-β1, leading to decreased differentiation of fibroblasts into myofibroblasts. Taken together, these results suggest that wound healing impairments in ageing are associated with increased levels of ROS, decreased SOD3 expression and impaired extracellular oxidative stress regulation. Our results identify SOD3 as a possible target to correct age-related cellular dysfunction in wound healing.

Leukemia Inhibitory Factor Protects Neurons from Ischemic Damage via Upregulation of Superoxide Dismutase 3

Leukemia inhibitory factor (LIF) has been shown to protect oligodendrocytes from ischemia by upregulating endogenous antioxidants. The goal of this study was to determine whether LIF protects neurons during stroke by upregulating superoxide dismutase 3 (SOD3). Animals were administered phosphate-buffered saline (PBS) or 125 μg/kg LIF at 6, 24, and 48 h after middle cerebral artery occlusion or sham surgery. Neurons were isolated from rat pups on embryonic day 18 and used between 7 and 15 days in culture. Cells were treated with LIF and/or 10 μM Akt inhibitor IV with PBS and 0.1 % DMSO acting as vehicle controls. Neurons transfected with scrambled or SOD3 small interfering RNA (siRNA) were subjected to 24-h ischemia after PBS or LIF treatment. LIF significantly increased superoxide dismutase activity and SOD3 expression in ipsilateral brain tissue compared to PBS. Following 24-h ischemia, LIF reduced cell death and increased SOD3 messenger RNA (mRNA) in vitro compared to PBS. Adding Akt inhibitor IV with LIF counteracted the decrease in cell death. Partially silencing the expression of SOD3 using siRNA prior to LIF treatment counteracted the protective effect of LIF-alone PBS treatment. These results indicate that LIF protects neurons in vivo and in vitro via upregulation of SOD3.

Clinical relevance of thyroid cell models in redox research

Background

Thyroid-derived cell models are commonly used to investigate the characteristics of thyroid cancers. It is noteworthy that each in vitro single cell model system imitates only a few characteristics of thyroid cancer depending on e.g. source of cells or oncogene used to transform the cells.

Methods

In the current work we utilized rat thyroid cancer cell models to determine their clinical relevance in redox gene studies by comparing in vitro expression data to thyroid Oncomine microarray database. To survey the cell lines we analyzed mRNA expression of genes that produce superoxide anion (nox family), genes that catalyze destruction of superoxide anion to hydrogen peroxide (sod family), and genes that remove hydrogen peroxide from cellular environment (catalase, gpx family and prdx family).

Results

Based on the current results, rat thyroid PC Cl3, PC PTC1, PC E1A, or FRLT5 cell models can be used to study NOX2, NOX4, SOD2, SOD3, CATALASE, GPX1, GPX2, GPX5, PRDX2, and PRDX3 gene expression and function.

Conclusions

Redox gene expression in rat originated single cell model systems used to study human thyroid carcinogenesis corresponds only partly with human redox gene expression, which may be caused by differences in redox gene activation stimulus. The data suggest careful estimation of the data observed in rat thyroid in vitro models.

Electronic supplementary material

The online version of this article (doi:10.1186/s12935-015-0264-3) contains supplementary material, which is available to authorized users.

Ras oncogene-mediated progressive silencing of extracellular superoxide dismutase in tumorigenesis

Extracellular superoxide dismutase (SOD3) is a secreted enzyme that uses superoxide anion as a substrate in a dismutase reaction that results in the formation of hydrogen peroxide. Both of these reactive oxygen species affect growth signaling in cells. Although SOD3 has growth-supporting characteristics, the expression of SOD3 is downregulated in epithelial cancer cells. In the current work, we studied the mechanisms regulating SOD3 expression in vitro using thyroid cell models representing different stages of thyroid cancer. We demonstrate that a low level of RAS activation increases SOD3 mRNA synthesis that then gradually decreases with increasing levels of RAS activation and the decreasing degree of differentiation of the cancer cells. Our data indicate that SOD3 regulation can be divided into two classes. The first class involves RAS–driven reversible regulation of SOD3 expression that can be mediated by the following mechanisms: RAS GTPase regulatory genes that are responsible for SOD3 self-regulation; RAS-stimulated p38 MAPK activation; and RAS-activated increased expression of the mir21 microRNA, which inversely correlates with sod3 mRNA expression. The second class involves permanent silencing of SOD3 mediated by epigenetic DNA methylation in cells that represent more advanced cancers. Therefore, the work suggests that SOD3 belongs to the group of ras oncogene-silenced genes.

Urotensin II Protects Cardiomyocytes from Apoptosis Induced by Oxidative Stress through the CSE/H2S Pathway

Plasma urotensin II (UII) has been observed to be raised in patients with acute myocardial infarction; suggesting a possible cardiac protective role for this peptide. However, the molecular mechanism is unclear. Here, we treated cultured cardiomyocytes with H₂O₂ to induce oxidative stress; observed the effect of UII on H₂O₂-induced apoptosis and explored potential mechanisms. UII pretreatment significantly reduced the number of apoptotic cardiomyocytes induced by H₂O₂; and it partly abolished the increase of pro-apoptotic protein Bax and the decrease of anti-apoptotic protein Bcl-2 in cardiomyocytes induced by H₂O₂. SiRNA targeted to the urotensin II receptor (UT) greatly inhibited these effects. Further analysis revealed that UII increased the production of hydrogen sulfide (H₂S) and the level of cystathionine-γ-lyase (CSE) by activating the ERK signaling in H₂O₂-treated-cardiomyocytes. Si-CSE or ERK inhibitor not only greatly inhibited the increase in CSE level or the phosphorylation of ERK induced by UII but also reversed anti-apoptosis of UII in H₂O₂-treated-cadiomyocytes. In conclusion, UII rapidly promoted the phosphorylation of ERK and upregulated CSE level and H₂S production, which in turn activated ERK signaling to protect cardiomyocytes from apoptosis under oxidative stress. These results suggest that increased plasma UII level may protect cardiomyocytes at the early-phase of acute myocardial infarction in patients.

Extracellular superoxide dismutase regulates the expression of small gtpase regulatory proteins GEFs, GAPs, and GDI

Extracellular superoxide dismutase (SOD3), which catalyzes the dismutation of superoxide anions to hydrogen peroxide at the cell membranes, regulates the cellular growth in a dose-dependent manner. This enzyme induces primary cell proliferation and immortalization at low expression levels whereas it activates cancer barrier signaling through the p53-p21 pathway at high expression levels, causing growth arrest, senescence, and apoptosis. Because previous reports suggested that the SOD3–induced reduction in the rates of cellular growth and migration also occurred in the absence of functional p53 signaling, in the current study we investigated the SOD3-induced growth-suppressive mechanisms in anaplastic thyroid cancer cells. Based on our data, the robust over-expression of SOD3 increased the level of phosphorylation of the EGFR, ERBB2, RYK, ALK, FLT3, and EPHA10 receptor tyrosine kinases with the consequent downstream activation of the SRC, FYN, YES, HCK, and LYN kinases. However, pull-down experiments focusing on the small GTPase RAS, RAC, CDC42, and RHO revealed a reduced level of growth and migration signal transduction, such as the lack of stimulation of the mitogen pathway, in the SOD3 over-expressing cells, which was confirmed by MEK1/2 and ERK1/2 Western blotting analysis. Interestingly, the mRNA expression analyses indicated that SOD3 regulated the expression of guanine nucleotide-exchange factors (RHO GEF16, RAL GEF RGL1), GTPase-activating proteins (ARFGAP ADAP2, RAS GAP RASAL1, RGS4), and a Rho guanine nucleotide-disassociation inhibitor (RHO GDI 2) in a dose dependent manner, thus controlling signaling through the small G protein GTPases. Therefore, our current data may suggest the occurrence of dose-dependent SOD3–driven control of the GTP loading of small G proteins indicating a novel growth regulatory mechanism of this enzyme.

Increased antioxidant defense mechanism in human adventitia-derived progenitor cells is associated with therapeutic benefit in ischemia

AIMS

Vascular wall-resident progenitor cells hold great promise for cardiovascular regenerative therapy. This study evaluates the impact of oxidative stress on the viability and functionality of adventitia-derived progenitor cells (APCs) from vein remnants of coronary artery bypass graft (CABG) surgery. We also investigated the antioxidant enzymes implicated in the resistance of APCs to oxidative stress-induced damage and the effect of interfering with one of them, the extracellular superoxide dismutase (EC-SOD/SOD3), on APC therapeutic action in a model of peripheral ischemia.

RESULTS

After exposure to hydrogen peroxide, APCs undergo apoptosis to a smaller extent than endothelial cells (ECs). This was attributed to up-regulation of antioxidant enzymes, especially SODs and catalase. Pharmacological inhibition of SODs increases reactive oxygen species (ROS) levels in APCs and impairs their survival. Likewise, APC differentiation results in SOD down-regulation and ROS-induced apoptosis. Oxidative stress increases APC migratory activity, while being inhibitory for ECs. In addition, oxidative stress does not impair APC capacity to promote angiogenesis in vitro. In a mouse limb ischemia model, an injection of naïve APCs, but not SOD3-silenced APCs, helps perfusion recovery and neovascularization, thus underlining the importance of this soluble isoform in protection from ischemia.

INNOVATION

This study newly demonstrates that APCs are endowed with enhanced detoxifier and antioxidant systems and that SOD3 plays an important role in their therapeutic activity in ischemia.

CONCLUSIONS

APCs from vein remnants of CABG patients express antioxidant defense mechanisms, which enable them to resist stress. These properties highlight the potential of APCs in cardiovascular regenerative medicine.

Extracellular superoxide dismutase induces mouse embryonic fibroblast proliferative burst, growth arrest, immortalization, and consequent in vivo tumorigenesis

AIMS

Rat sarcoma virus (RAS)-induced tumorigenesis has been suggested to follow a three-stage model consisting of an initial RAS activation, senescence induction, and evasion of p53-dependent senescence checkpoints. While reactive oxygen species act as second messengers in RAS-induced senescence, they are also involved in oncogenic transformation by inducing proliferation and promoting mutations. In the current work, we investigated the role of extracellular superoxide dismutase (SOD3) in RAS-induced senescence and immortalization in vitro and in vivo. We used a mouse embryonic fibroblast (MEF) primary cell model along with immortalized and transformed human cell lines derived from papillary and anaplastic thyroid cancer.

RESULTS

Based on our data, sod3 RNA interference in H-RasV12-transduced cells markedly inhibited cell growth, while sod3 over-expression in MEFs initially caused a proliferative burst followed by the activation of DNA damage checkpoints, induction of p53-p21 signal transduction, and senescence. Subsequently, sod3-transduced MEF cells developed co-operative p21-p16 down-regulation and acquired transformed cell characteristics such as increased telomerase activity, loss of contact inhibition, growth in low-nutrient conditions, and in vivo tumorigenesis. Interestingly, as previously reported with RAS, we showed a dose-dependent response to SOD3 in vitro and in vivo involving transcriptional and non-transcriptional regulatory mechanisms.

INNOVATION

SOD3 may mediate H-RasV12-induced initiation of primary cell immortalization.

CONCLUSIONS

Our results indicate that SOD3 influences growth signaling in primary and cancer cells downstream of the ras oncogene and could serve as a therapy target at an early tumorigenesis phase.

Analysis of extracellular superoxide dismutase and Akt in ascending aortic aneurysm with tricuspid or bicuspid aortic valve

Ascending aortic aneurysm (AsAA) is a consequence of medial degeneration (MD), deriving from apoptotic loss of smooth muscle cells (SMC) and fragmentation of elastin and collagen fibers. Alterations of extracellular matrix structure and protein composition, typical of medial degeneration, can modulate intracellular pathways. In this study we examined the relevance of extracellular superoxide dismutase (SOD3) and Akt in AsAA pathogenesis, evaluating their tissue distribution and protein levels in ascending aortic tissues from controls (n=6), patients affected by AsAA associated to tricuspid aortic valve (TAV, n=9) or bicuspid aortic valve (BAV, n=9). The results showed a significant reduction of SOD3, phospho-Akt and Akt protein levels in AsAA tissues from patients with BAV, compared to controls, whereas the differences observed between controls and patients with TAV were not significant. The decreased levels of SOD3 and Akt in BAV aortic tissues are associated with decreased Erk1/Erk2 phosphorylation and MMP-9 levels increase. The authors suggest a role of decreased SOD3 protein levels in the progression of AsAA with BAV and a link between ECM modifications of aortic media layer and impaired Erk1/Erk2 and Akt signaling in the late stages of the aortopathy associated with BAV.

Sustained oxidative stress causes late acute renal failure via duplex regulation on p38 MAPK and Akt phosphorylation in severely burned rats

BACKGROUND

Clinical evidence indicates that late acute renal failure (ARF) predicts high mortality in severely burned patients but the pathophysiology of late ARF remains undefined. This study was designed to test the hypothesis that sustained reactive oxygen species (ROS) induced late ARF in a severely burned rat model and to investigate the signaling mechanisms involved.

MATERIALS AND METHODS

Rats were exposed to 100°C bath for 15 s to induce severe burn injury (40% of total body surface area). Renal function, ROS generation, tubular necrosis and apoptosis, and phosphorylation of MAPK and Akt were measured during 72 hours after burn.

RESULTS

Renal function as assessed by serum creatinine and blood urea nitrogen deteriorated significantly at 3 h after burn, alleviated at 6 h but worsened at 48 h and 72 h, indicating a late ARF was induced. Apoptotic cells and cleavage caspase-3 in the kidney went up slowly and turned into significant at 48 h and 72 h. Tubular cell ROS production shot up at 6 h and continuously rose during the 72-h experiment. Scavenging ROS with tempol markedly attenuated tubular apoptosis and renal dysfunction at 72 h after burn. Interestingly, renal p38 MAPK phosphorylation elevated in a time dependent manner whereas Akt phosphorylation increased during the first 24 h but decreased at 48 h after burn. The p38 MAPK specific inhibitor SB203580 alleviated whereas Akt inhibitor exacerbated burn-induced tubular apoptosis and renal dysfunction. Furthermore, tempol treatment exerted a duplex regulation through inhibiting p38 MAPK phosphorylation but further increasing Akt phosphorylation at 72 h postburn.

CONCLUSIONS

These results demonstrate that sustained renal ROS overproduction induces continuous tubular cell apoptosis and thus a late ARF at 72 h after burn in severely burned rats, which may result from ROS-mediated activation of p38 MAPK but a late inhibition of Akt phosphorylation.

Sperm mRNA transcripts are indicators of sub-chronic low dose testicular injury in the Fischer 344 rat

Current human reproductive risk assessment methods rely on semen and serum hormone analyses, which are not easily comparable to the histopathological endpoints and mating studies used in animal testing. Because of these limitations, there is a need to develop universal evaluations that reliably reflect male reproductive function. We hypothesized that toxicant-induced testicular injury can be detected in sperm using mRNA transcripts as indicators of insult. To test this, we exposed adult male Fischer 344 rats to low doses of model testicular toxicants and classically characterized the testicular injury while simultaneously evaluating sperm mRNA transcripts from the same animals. Overall, this study aimed to: 1) identify sperm transcripts altered after exposure to the model testicular toxicant, 2,5-hexanedione (HD) using microarrays; 2) expand on the HD-induced transcript changes in a comprehensive time course experiment using qRT-PCR arrays; and 3) test these injury indicators after exposure to another model testicular toxicant, carbendazim (CBZ). Microarray analysis of HD-treated adult Fischer 344 rats identified 128 altered sperm mRNA transcripts when compared to control using linear models of microarray analysis (q<0.05). All transcript alterations disappeared after 3 months of post-exposure recovery. In the time course experiment, time-dependent alterations were observed for 12 candidate transcripts selected from the microarray data based upon fold change and biological relevance, and 8 of these transcripts remained significantly altered after the 3-month recovery period (p<0.05). In the last experiment, 8 candidate transcripts changed after exposure to CBZ (p<0.05). The two testicular toxicants produced distinct molecular signatures with only 4 overlapping transcripts between them, each occurring in opposite directions. Overall, these results suggest that sperm mRNA transcripts are indicators of low dose toxicant-induced testicular injury in the rat.

The pro-inflammatory cytokine IL-22 up-regulates keratin 17 expression in keratinocytes via STAT3 and ERK1/2

BACKGROUND

To investigate the regulation of K17 expression by the pro-inflammatory cytokine IL-22 in keratinocytes and its important role in our previously hypothesized "K17/T cell/cytokine autoimmune loop" in psoriasis.

MATERIALS AND METHODS

K17 expression was examined in the IL-22-treated keratinocytes by real-time quantitative PCR, ELISA, Western blot and Immunofluorescence. In addition, the signaling pathways involved in K17 regulation were investigated with related inhibitors and siRNAs. In addition, K17 expression was examined in the epidermis of IL-22-injected mouse skin.

RESULTS

IL-22-induced K17 expression was confirmed in keratinocytes and the epidermis of IL-22-injected mouse skin at both mRNA and protein levels, which is an important complement to the autoimmune loop. We further investigated the regulatory mechanisms and found that both STAT3 and ERK1/2 were involved in the up-regulation of K17 expression induced by IL-22.

CONCLUSION

IL-22 up-regulates K17 expression in keratinocytes in a dose-dependent manner through STAT3- and ERK1/2-dependent mechanisms. These findings indicated that IL-22 was also involved in the K17/T cell/cytokine autoimmune loop and may play an important role in the progression of psoriasis.

Free radical generation induces epithelial-to-mesenchymal transition in lung epithelium via a TGF-β1-dependent mechanism

Fibrotic remodelling of lung parenchymal and airway compartments is the major contributor to life-threatening organ dysfunction in chronic lung diseases such as idiopathic pulmonary fibrosis (IPF) and Chronic Obstructive Pulmonary Disease (COPD). Since transforming growth factor-β1 (TGF-β1) is believed to play a key role in disease pathogenesis and markers of oxidative stress are also commonly detected in bronchoalveolar lavage (BAL) from such patients we sought to investigate whether both factors might be interrelated. Here we investigated the hypothesis that oxidative stress to the lung epithelium promotes fibrotic repair by driving epithelial-to-mesenchymal transition (EMT) via the augmentation of TGF-β1. We show that in response to 400μM hydrogen peroxide (H(2)O(2)) A549 cells, used a model for alveolar epithelium, and human primary bronchial epithelial cells (PBECs) undergo EMT displaying morphology changes, decreased expression of epithelial markers (E-cadherin and ZO-1), increased expression of mesenchymal markers (vimentin and α-smooth muscle actin) as well as increased secretion of extracelluar matrix components. The same oxidative stress also promotes expression of TGF-β1. Inhibition of TGF-β1 signalling as well as treatment with antioxidants such as phenyl tert-butylnitrone (PBN) and superoxide dismutase 3 (SOD3) prevent the oxidative stress driven EMT-like changes described above. Interventions also inhibited EMT-like changes. This study identifies a link between oxidative stress, TGF-β1 and EMT in lung epithelium and highlights the potential for antioxidant therapies to limit EMT and its potential contribution to chronic lung disease.

Superoxide dismutase 3 limits collagen-induced arthritis in the absence of phagocyte oxidative burst

Extracellular superoxide dismutase (SOD3), an enzyme mediating dismutation of superoxide into hydrogen peroxide, has been shown to reduce inflammation by inhibiting macrophage migration into injured tissues. In inflamed tissues, superoxide is produced by the phagocytic NOX2 complex, which consists of the catalytic subunit NOX2 and several regulatory subunits (e.g., NCF1). To analyze whether SOD3 can regulate inflammation in the absence of functional NOX2 complex, we injected an adenoviral vector overexpressing SOD3 directly into the arthritic paws of Ncf1^∗/∗ mice with collagen-induced arthritis. SOD3 reduced arthritis severity in both oxidative burst-deficient Ncf1^∗/∗ mice and also in wild-type mice. The NOX2 complex independent anti-inflammatory effect of SOD3 was further characterized in peritonitis, and SOD3 was found to reduce macrophage infiltration independently of NOX2 complex functionality. We conclude that the SOD3-mediated anti-inflammatory effect on arthritis and peritonitis operates independently of NOX2 complex derived oxidative burst.