Overexpression of extracellular superoxide dismutase decreases lung injury after exposure to oil fly ash

Redox and inflammatory mechanisms linking air pollution particulate matter with cardiometabolic derangements

Air pollution is the largest environmental risk factor for disease and premature death. Among the different components that are present in polluted air, fine particulate matter below 2.5 μm in diameter (PM2.5) has been identified as the main hazardous constituent. PM2.5 mainly arises from fossil fuel combustion during power generation, industrial processes, and transportation. Exposure to PM2.5 correlates with enhanced mortality risk from cardiovascular diseases (CVD), such as myocardial infarction and stroke. Over the last decade, it has been increasingly suggested that PM2.5 affects CVD already at the stage of risk factor development. Among the multiple biological mechanisms that have been described, the interplay between oxidative stress and inflammation has been consistently highlighted as one of the main drivers of pulmonary, systemic, and cardiovascular effects of PM2.5 exposure. In this context, PM2.5 uptake by tissue-resident immune cells in the lung promotes oxidative and inflammatory mediators release that alter tissue homeostasis at remote locations. This pathway is central for PM2.5 pathogenesis and might account for the accelerated development of risk factors for CVD, including obesity and diabetes. However, transmission and end-organ mechanisms that explain PM2.5-induced impaired function in metabolic active organs are not completely understood. In this review, the main features of PM2.5 physicochemical characteristics related to PM2.5 ability to induce oxidative stress and inflammation will be presented. Hallmark and recent epidemiological and interventional studies will be summarized and discussed in the context of current air quality guidelines and legislation, knowledge gaps, and inequities. Lastly, mechanistic studies at the intersection between redox metabolism, inflammation, and function will be discussed, with focus on heart and adipose tissue alterations. By offering an integrated analysis of PM2.5-induced effects on cardiometabolic derangements, this review aims to contribute to a better understanding of the pathogenesis and potential interventions of air pollution-related CVD.

The macrophage senescence hypothesis: the role of poor heat shock response in pulmonary inflammation and endothelial dysfunction following chronic exposure to air pollution

INTRODUCTION

Cardiovascular diseases (CVD) have been associated with high exposure to fine particulate air pollutants (PM_2.5). Alveolar macrophages are the first defense against inhaled particles. As soon as they phagocytize the particles, they reach an inflammatory phenotype, which affects the surrounding cells and associates with CVD. Not coincidentally, CVD are marked by a depleted heat shock response (HSR), defined by a deficit in inducing 70-kDa heat shock protein (HSP70) expression during stressful conditions. HSP70 is a powerful anti-inflammatory chaperone, whose reduced levels trigger a pro-inflammatory milieu, cellular senescence, and a senescence-associated secretory phenotype (SASP). However, whether macrophage senescence is the main mechanism by which PM_2.5 propagates low-grade inflammation remains unclear.

OBJECTIVE AND DESIGN

In this article, we review evidence supporting that chronic exposure to PM_2.5 depletes HSR and determines the ability to solve the initial stress.

RESULTS AND DISCUSSION

When exposed to PM_2.5, macrophages increase the production of reactive oxygen species, which activate nuclear factor-kappa B (NF-κB). NF-κB is naturally a pro-inflammatory factor that drives prostaglandin E2 (PGE2) synthesis and causes fever. PGE2 can be converted into prostaglandin A2, a powerful inducer of HSR. Therefore, when transiently activated, NF-κB can trigger the anti-inflammatory response through negative feedback, by inducing HSP70 expression. However, when chronically activated, NF-κB heads a set of pathways involved in mitochondrial dysfunction, endoplasmic reticulum stress, unfolded protein response, inflammasome activation, and apoptosis. During chronic exposure to PM_2.5, cells cannot properly express sirtuin-1 or activate heat shock factor-1 (HSF-1), which delays the resolution phase of inflammation. Since alveolar macrophages are the first immune defense against PM_2.5, we suppose that the pollutant impairs HSR and, consequently, induces cellular senescence. Accordingly, senescent macrophages change its secretory phenotype to a more inflammatory one, known as SASP. Finally, macrophages' SASP would propagate the systemic inflammation, leading to endothelial dysfunction and atherosclerosis.

The Interplay of Oxidative Stress and ROS Scavenging: Antioxidants as a Therapeutic Potential in Sepsis

Oxidative stress resulting from the disproportion of oxidants and antioxidants contributes to both physiological and pathological conditions in sepsis. To combat this, the antioxidant defense system comes into the picture, which contributes to limiting the amount of reactive oxygen species (ROS) leading to the reduction of oxidative stress. However, a strong relationship has been found between scavengers of ROS and antioxidants in preclinical in vitro and in vivo models. ROS is widely believed to cause human pathology most specifically in sepsis, where a small increase in ROS levels activates signaling pathways to initiate biological processes. An inclusive understanding of the effects of ROS scavenging in cellular antioxidant signaling is essentially lacking in sepsis. This review compiles the mechanisms of ROS scavenging as well as oxidative damage in sepsis, as well as antioxidants as a potent therapeutic. Direct interaction between ROS and cellular pathways greatly affects sepsis, but such interaction does not provide the explanation behind diverse biological outcomes. Animal models of sepsis and a number of clinical trials with septic patients exploring the efficiency of antioxidants in sepsis are reviewed. In line with this, both enzymatic and non-enzymatic antioxidants were effective, and results from recent studies are promising. The usage of these potent antioxidants in sepsis patients would greatly impact the field of medicine.

The Effect of Extracellular Superoxide Dismutase (SOD3) Gene in Lung Cancer

Background

The recognition of new diagnostic and prognostic biological markers for lung cancer, the most severe malignant tumor, is an essential and eager study. In a microenvironment, superoxide dismutase 3 (SOD3) can adjust active oxygen, and it refers to a secreted antioxidant enzyme. It was also found to be cancer-related, and in lung cancer, it was remarkably down-regulated. More and more new cancer research focuses on the function of SOD3. Despite this, there is no good description of SOD3 function in the LC progression.

Methods

Through bioinformatics analysis, we found that SOD3 was a possible novel lung cancer gene in this study. We analyzed data sets from Gene Expression Comprehensive Database (GEO) and the Cancer Genome Atlas (TCGA), and SOD3 expression was studied in lung cancer. This study estimated the SOD3 diagnosis and prognosis through gene expression differential display, gene set enrichment analysis (GSEA), enrichment and genomes (KEGG) analysis, and gene ontology (GO). Then in order to investigate the SOD3 presentation in lung cancer cells, we used Western Blot and also applied Flow cytometry to detect the impact of anti-tumor medicine on tumor cell apoptosis.

Results

We found that the expression level of SOD3 in lung cancer was low (P = 4.218E-29), while the survival of lung cancer patients with high SOD3 expression was shorter (LUSC p =0.00086, LUAD p=0.00038). According to the result of western blot, the expression of SOD3 in tumor cells was higher than that in normal cells. The ratio of early apoptosis induced by anti-cancer drugs was 10.5% in normal cells, 35.1% in squamous cell carcinoma and 36.9% in adenocarcinoma.The SOD3 high expression was associated with poor survival probability by multivariate analysis (HR: 1.006, 95% CI 1.002–1.011, p=0.006). Moreover, SOD3 high expression group had higher ESTIMATE scores, and larger amount of immune infiltrating cells. SOD3 expression is correlated with PDCD1 and CTLA4 expression.

Conclusions

SOD3 gene can be used as a prognostic gene in lung cancer patients, and lung cancer patients with high expression of this gene can reap worse prognostic outcome. It can be used as a new clinical method and prognosticator for lung cancer patients.

Chronic exposure to polluted urban air aggravates myocardial infarction by impaired cardiac mitochondrial function and dynamics

Air pollution exposure positively correlates with increased cardiovascular morbidity and mortality rates, mainly due to myocardial infarction (MI). Herein, we aimed to study the metabolic mechanisms underlying this association, focusing on the evaluation of cardiac mitochondrial function and dynamics, together with its impact over MI progression. An initial time course study was performed in BALB/c mice breathing filtered air (FA) or urban air (UA) in whole-body exposure chambers located in Buenos Aires City downtown for up to 16 weeks (n = 8 per group and time point). After 12 weeks, lung inflammatory cell recruitment was evident in UA-exposed mice. Interestingly, impaired redox metabolism, characterized by decreased lung SOD activity and increased GSSG levels and NOX activity, precede local inflammation in this group. At this selected time point, additional mice were exposed to FA or UA (n = 12 per group) and alveolar macrophage PM uptake and nitric oxide (NO) production was observed in UA-exposed mice, together with increased pro-inflammatory cytokine levels (TNF-α and IL-6) in BAL and plasma. Consequently, impaired heart tissue oxygen metabolism and altered mitochondrial ultrastructure and function were observed in UA-exposed mice after 12 weeks, characterized by decreased active state respiration and ATP production rates, and enhanced mitochondrial H₂O₂ production. Moreover, disturbed cardiac mitochondrial dynamics was detected in this group. This scenario led to a significant increase in the area of infarcted tissue following myocardial ischemia reperfusion injury in vivo, from 43 ± 3% of the area at risk in mice breathing FA to 66 ± 4% in UA-exposed mice (n = 6 per group, p < 0.01), together with a sustained increase in LVEDP during myocardial reperfusion. Taken together, our data unravel cardiac mitochondrial mechanisms that contribute to the understanding of the adverse health effects of urban air pollution exposure, and ultimately highlight the importance of considering environmental factors in the development of cardiovascular diseases.

Ovariectomy reduces the cardiac cytoprotection in rats exposed to particulate air pollutant

Fine particulate matter (PM_2.5) has been considered a risk factor for cardiovascular diseases by inducing an oxidative and inflammatory phenotype. Besides, the reduction of 17β-estradiol (E2) levels during menopause is a natural risk for cardiovascular outcomes. During the E2 downfall, there is a high requirement of the 70-kDa heat shock proteins (HSP70), which present essential antioxidant, anti-inflammatory, and anti-senescence roles. We investigated if the ovariectomy, an animal model for menopause, could induce additional effects in cardiac health by impairing oxidative and heat shock response parameters of female rats chronically exposed to residual oil fly ash (ROFA; an inorganic fraction of PM_2.5). Thus, ROFA was obtained from São Paulo (Brazil) and solubilized it in saline. Further, female Wistar rats were exposed to 50 μL of saline (control group) or ROFA solution (250 μg) (polluted) by intranasal instillation, 5 days/week, 12 weeks. At the 12th week, animals were subdivided into four groups (n = 6 p/group): control, OVX, polluted, and polluted + OVX. Control and polluted were submitted to false surgery, while OVX and polluted + OVX were ovariectomized. ROFA or saline exposure continued for 12 weeks. Ovariectomy reduced the cardiac catalase activity and iHSP70 expression in female rats exposed to ROFA. Neither plasma eHSP72 levels nor H-index (eHSP72 to cardiac iHSP70 ratio) was affected. In conclusion, ovariectomy reduces the cardiac cytoprotection and antioxidant defense, and enhances the susceptibility to premature cellular senescence in rats exposed to ROFA.

Superoxide dismutase: an updated review on its health benefits and industrial applications

Many short-lived and highly reactive oxygen species, such as superoxide anion (O₂^-) and hydrogen peroxide (H₂O₂), are toxic or can create oxidative stress in cells, a response involved in the pathogenesis of numerous diseases depending on their concentration, location, and cellular conditions. Superoxide dismutase (SOD) activities as an endogenous and exogenous cell defense mechanism include the potential use in treating various diseases, improving the potential use in treating various diseases, and improving food-stuffs preparation dietary supplements human nutrition. Published work indicates that SOD regulates oxidative stress, lipid metabolism, inflammation, and oxidation in cells. It can prevent lipid peroxidation, the oxidation of low-density lipoprotein in macrophages, lipid droplets' formation, and the adhesion of inflammatory cells into endothelial monolayers. It also expresses antioxidant effects in numerous cancer-related processes. Additionally, different forms of SOD may also augment food processing and pharmaceutical applications, exhibit anticancer, antioxidant, and anti-inflammatory effects, and prevent arterial problems by protecting the proliferation of vascular smooth muscle cells. Many investigations in this review have reported the therapeutic ability and physiological importance of SOD. Because of their antioxidative effects, SODs are of great potential in the medicinal, cosmetic, food, farming and chemical industries. This review discusses the findings of human and animal studies that support the advantages of SOD enzyme regulations to reduce the formation of oxidative stress in various ways.

Novel predictor markers for early differentiation between transient tachypnea of newborn and respiratory distress syndrome in neonates

Neonatal Respiratory Distress Syndrome (RDS) and Transient Tachypnea of newborn (TTN) are common similar neonatal respiratory diseases. Study the early predictor markers in differentiation between TTN and RDS in neonates. A prospective case control study which was done in Neonatal Intensive Care Unit (NICU) of Tanta University Hospital (TUH) from September 2016 to March 2018. Three groups of neonates were included in the study: RDS group (45 neonates), TTN group (45 neonates), and control group (45 healthy neonates). There were statistically significant difference (SSD) between our studied three groups as regard serum Malondialdehyde (MDA), Superoxide dismutase SOD, Lactate dehydrogenase (LDH), and blood PH and P-values were 0.001* for these comparative parameters. The ROC curve of RDS cases revealed that the serum MDA Cut off, sensitivity and specificity were 1.87 mmol/L, 98%, 96%, respectively which had the highest sensitivity and specificity followed by the serum SOD then the serum LDH and lastly the blood PH while in TTN cases, the serum MDA Cut off, sensitivity and specificity were 0.74 mmol/L, 96%, 93%, respectively then the serum SOD then the serum LDH and lastly the blood PH. Serum MDA, SOD, LDH, and PH had a beneficial role as early predictors in differentiation between TTN and RDS in neonates.

Fine and coarse particulate matter, trace element content, and associated health risks considering respiratory deposition for Ergene Basin, Thrace

Ergene Basin is located in Thrace, Turkey, where industries are densely populated. This study aimed to determine exposure of people living in Ergene Basin (Çorlu and Çerkezköy) to fine and coarse PM, and its potentially toxic element (PTE) content by considering variation in respiratory airway deposition rates with daily activities and PM particle size by employing deposition models of International Commission on Radiological Protection and Multiple Path Particle Dosimetry. Fine and coarse PM samples were collected daily for a year at points in Çorlu and Çerkezköy representing urban and industrial settings, respectively. A questionnaire survey was conducted in the study area to obtain time-activity budgets, and associated variation was included in the health risk assessment by considering time-activity-dependent inhalation rates. The studied PTEs were Al, As, Ba, Cd, Cr, Co, Mn, Ni, Pb, and Se. The mean fine and coarse PM concentrations were measured as 23 and 14 μg/m³ in Çorlu, and 22 and 12 μg/m³ in Çerkezköy, respectively. The only PTE that exceeded acceptable risk in terms of total carcinogenic risk was Cr. Non-carcinogenic risks of all the PTEs including Cr were below the threshold. The use of deposition fractions in the health risk assessment (HRA) calculations was found to prevent overestimation of health risks by at least 91% and 87% for fine and coarse PM, respectively, compared to the regular HRA. Minor differences in risk between Çorlu and Çerkezköy suggest that urban pollution sources could be at least as influential on human health as industrial sources.

Ovariectomy enhances female rats' susceptibility to metabolic, oxidative, and heat shock response effects induced by a high-fat diet and fine particulate matter

Obesity and exposure to fine particulate matter (air pollutant PM_2.5) are important risk factors for metabolic and cardiovascular diseases. They are also related to early menopause. The reduction of 17β-estradiol (E2) levels during female climacteric, marked by menopause, is of significant concern because of its imminent influence on metabolism, redox and inflammatory status. This complex homeostasis-threatening scenario may induce a heat shock response (HSR) in cells, enhancing the expression of the 70 kDa heat shock protein (HSP70). A failure in this mechanism could predispose women to cardiovascular diseases. In this study, we evaluated if the climacteric could represent an additional risk among obese rats exposed to PM_2.5 by worsening lipid, oxidative, and inflammatory parameters and HSP70 in cardiac tissue. We induced obesity in female Wistar rats using a high-fat diet (HFD) (58.3% as fats) and exposed them to 50 μL of saline 0.9% (control, n = 15) or 250 μg residual oil fly ash (ROFA, the inorganic portion of PM_2.5) (polluted, n = 15) by intranasal instillation, 5 days/w for 12 weeks. At the 12th week, we subdivided these animals into four groups: control (n = 6), OVX (n = 9), polluted (n = 6) and polluted + OVX (n = 9). OVX and polluted + OVX were submitted to a bilateral ovariectomy (OVX), a surgical model for menopause, while control and polluted received a false surgery (sham). ROFA exposure and HFD consumption were continued for 12 additional weeks, after which the animals were euthanized. ROFA enhanced the susceptibility to ovariectomy-induced dyslipidemia, while ovariectomy predisposed female rats to the ROFA-induced decrease of cardiac iHSP70 expression. Ovariectomy also decreased the IL-6 levels and IL-6/IL-10 in obese animals, reinforcing a metabolic impairment and a failure to respond to unfavorable conditions. Our results support the hypothesis that obese ovariectomized animals are predisposed to a metabolic worsening under polluted conditions and are at higher risk of cardiovascular diseases.

NADPH oxidase and mitochondria are relevant sources of superoxide anion in the oxinflammatory response of macrophages exposed to airborne particulate matter

Exposure to ambient air particulate matter (PM) is associated with increased cardiorespiratory morbidity and mortality. In this context, alveolar macrophages exhibit proinflammatory and oxidative responses as a result of the clearance of particles, thus contributing to lung injury. However, the mechanisms linking these pathways are not completely clarified. Therefore, the oxinflammation phenomenon was studied in RAW 264.7 macrophages exposed to Residual Oil Fly Ash (ROFA), a PM surrogate rich in transition metals. While cell viability was not compromised under the experimental conditions, a proinflammatory phenotype was observed in cells incubated with ROFA 100 μg/mL, characterized by increased levels of TNF-α and NO production, together with PM uptake. This inflammatory response seems to precede alterations in redox metabolism, characterized by augmented levels of H₂O₂, diminished GSH/GSSG ratio, and increased SOD activity. This scenario resulted in increased oxidative damage to phospholipids. Moreover, alterations in mitochondrial respiration were observed following ROFA incubation, such as diminished coupling efficiency and spare respiratory capacity, together with augmented proton leak. These findings were accompanied by a decrease in mitochondrial membrane potential. Finally, NADPH oxidase (NOX) and mitochondria were identified as the main sources of superoxide anion () in our model. These results indicate that PM exposure induces direct activation of macrophages, leading to inflammation and increased reactive oxygen species production through NOX and mitochondria, which impairs antioxidant defense and may cause mitochondrial dysfunction.

Pathogenic Role of Air Pollution Particulate Matter in Cardiometabolic Disease: Evidence from Mice and Humans

Significance: Air pollution is a considerable global threat to human health that dramatically increases the risk for cardiovascular pathologies, such as atherosclerosis, myocardial infarction, and stroke. An estimated 4.2 million cases of premature deaths worldwide are attributable to outdoor air pollution. Among multiple other components, airborne particulate matter (PM) has been identified as the major bioactive constituent in polluted air. While PM-related illness was historically thought to be confined to diseases of the respiratory system, overwhelming clinical and experimental data have now established that acute and chronic exposure to PM causes a systemic inflammatory and oxidative stress response that promotes cardiovascular disease. Recent Advances: A large body of evidence has identified an impairment of redox metabolism and the generation of oxidatively modified lipids and proteins in the lung as initial tissue response to PM. In addition, the pathogenicity of PM is mediated by an inflammatory response that involves PM uptake by tissue-resident immune cells, the activation of proinflammatory pathways in various cell types and organs, and the release of proinflammatory cytokines as locally produced tissue response signals that have the ability to affect organ function in a remote manner. Critical Issues: In the present review, we summarize and discuss the functional participation of PM in cardiovascular pathologies and its risk factors with an emphasis on how oxidative stress, inflammation, and immunity interact and synergize as a response to PM. Future Directions: The impact of PM constituents, doses, and novel anti-inflammatory therapies against PM-related illness is also discussed.

Lung SOD3 limits neurovascular reperfusion injury and systemic immune activation following transient global cerebral ischemia

BACKGROUND AND OBJECTIVES

Studies implicate the lung in moderating systemic immune activation via effects on circulating leukocytes. In this study, we investigated whether targeted expression of the antioxidant extracellular superoxide dismutase (SOD3) within the lung would influence post-ischemic peripheral neutrophil activation and CNS reperfusion injury.

METHODS

Adult, male mice expressing human SOD3 within type II pneumocytes were subjected to 15 min of transient global cerebral ischemia. Three days post-reperfusion, lung and brain tissue was collected and analyzed by immunohistochemistry for inflammation and injury markers. In vitro motility and neurotoxicity assays were conducted to ascertain the direct effects of hSOD3 on PMN activation. Results were compared against C57BL/6 age and sex-matched controls.

RESULTS

Relative to wild-type controls, hSOD3 heterozygous mice exhibited a reduction in lung inflammation, blood-brain barrier damage, and post-ischemic neuronal injury within the hippocampus and cortex. PMNs harvested from hSOD3 mice were also resistant to LPS priming, slower-moving, and less toxic to primary neuronal cultures.

CONCLUSIONS

Constitutive, focal expression of hSOD3 is neuroprotective in a model of global cerebral ischemia-reperfusion injury. The underlying mechanism of SOD3-dependent protection is attributable in part to effects on the activation state and toxic potential of circulating neutrophils. These results implicate lung-brain coupling as a determinant of cerebral ischemia-reperfusion injury and highlight post-stroke lung inflammation as a potential therapeutic target in acute ischemic cerebrovascular injuries.

Role of Mitochondria in the Redox Signaling Network and Its Outcomes in High Impact Inflammatory Syndromes

Inflammation is associated with the release of soluble mediators that drive cellular activation and migration of inflammatory leukocytes to the site of injury, together with endothelial expression of adhesion molecules, and increased vascular permeability. It is a stepwise tightly regulated process that has been evolved to cope with a wide range of different inflammatory stimuli. However, under certain physiopathological conditions, the inflammatory response overwhelms local regulatory mechanisms and leads to systemic inflammation that, in turn, might affect metabolism in distant tissues and organs. In this sense, as mitochondria are able to perceive signals of inflammation is one of the first organelles to be affected by a dysregulation in the systemic inflammatory response, it has been associated with the progression of the physiopathological mechanisms. Mitochondria are also an important source of ROS (reactive oxygen species) within most mammalian cells and are therefore highly involved in oxidative stress. ROS production might contribute to mitochondrial damage in a range of pathologies and is also important in a complex redox signaling network from the organelle to the rest of the cell. Therefore, a role for ROS generated by mitochondria in regulating inflammatory signaling was postulated and mitochondria have been implicated in multiple aspects of the inflammatory response. An inflammatory condition that affects mitochondrial function in different organs is the exposure to air particulate matter (PM). Both after acute and chronic pollutants exposure, PM uptake by alveolar macrophages have been described to induce local cell activation and recruitment, cytokine release, and pulmonary inflammation. Afterwards, inflammatory mediators have been shown to be able to reach the bloodstream and induce a systemic response that affects metabolism in distant organs different from the lung. In this proinflammatory environment, impaired mitochondrial function that leads to bioenergetic dysfunction and enhanced production of oxidants have been shown to affect tissue homeostasis and organ function. In the present review, we aim to discuss the latest insights into the cellular and molecular mechanisms that link systemic inflammation and mitochondrial dysfunction in different organs, taking the exposure to air pollutants as a case model.

iNOS Inhibition Reduces Lung Mechanical Alterations and Remodeling Induced by Particulate Matter in Mice

Background. The epidemiologic association between pulmonary exposure to ambient particulate matter (PM) and acute lung damage is well known. However, the mechanism involved in the effects of repeated exposures of PM in the lung injury is poorly documented. This study tested the hypotheses that chronic nasal instillation of residual oil fly ash (ROFA) induced not only distal lung and airway inflammation but also remodeling. In addition, we evaluated the effects of inducible nitric oxide inhibition in these responses. For this purpose, airway and lung parenchyma were evaluated by quantitative analysis of collagen and elastic fibers, immunohistochemistry for macrophages, neutrophils, inducible nitric oxide synthase (iNOS), neuronal nitric oxide synthase (nNOS), and alveolar septa 8-iso prostaglandin F2α (8-iso-PGF-2α) detection. Anesthetized in vivo (airway resistance, elastance, H, G, and Raw) respiratory mechanics were also analyzed. C57BL6 mice received daily 60ul of ROFA (intranasal) for five (ROFA-5d) or fifteen days (ROFA-15d). Controls have received saline (SAL). Part of the animals has received 1400W (SAL+1400W and ROFA-15d+1400W), an iNOS inhibitor, for four days before the end of the protocol. A marked neutrophil and macrophage infiltration and an increase in the iNOS, nNOS, and 8-iso-PGF2 α expression was observed in peribronchiolar and alveolar wall both in ROFA-5d and in ROFA-15d groups. There was an increment of the collagen and elastic fibers in alveolar and airway walls in ROFA-15d group. The iNOS inhibition reduced all alterations induced by ROFA, except for the 8-iso-PGF2 α expression. In conclusion, repeated particulate matter exposures induce extracellular matrix remodeling of airway and alveolar walls, which could contribute to the pulmonary mechanical changes observed. The mechanism involved is, at least, dependent on the inducible nitric oxide activation.

Extracellular Superoxide Dismutase Enhances Recruitment of Immature Neutrophils to the Liver

Listeria monocytogenes is a Gram-positive intracellular pathogen that causes spontaneous abortion in pregnant women, as well as septicemia, meningitis, and gastroenteritis, primarily in immunocompromised individuals. Although L. monocytogenes can usually be effectively treated with antibiotics, there is still around a 25% mortality rate with individuals who develop clinical listeriosis. Neutrophils are innate immune cells required for the clearance of pathogenic organisms, including L. monocytogenes The diverse roles of neutrophils during both infectious and noninfectious inflammation have recently gained much attention. However, the impact of reactive oxygen species, and the enzymes that control their production, on neutrophil recruitment and function is not well understood. Using congenic mice with varying levels of extracellular superoxide dismutase (ecSOD) activity, we have recently shown that the presence of ecSOD decreases clearance of L. monocytogenes while increasing the recruitment of neutrophils that are not protective in the liver. The data presented here show that ecSOD activity does not lead to a cell-intrinsic increase in neutrophil-homing potential or a decrease in protection against L. monocytogenes Instead, ecSOD activity enhances the production of neutrophil-attracting factors and protects hyaluronic acid (HA) from damage. Furthermore, neutrophils from the livers of ecSOD-expressing mice have decreased intracellular and surface-bound myeloperoxidase, are less capable of killing phagocytosed L. monocytogenes, and have decreased oxidative burst. Collectively, our data reveal that ecSOD activity modulates neutrophil recruitment and function in a cell-extrinsic fashion, highlighting the importance of the enzyme in protecting tissues from oxidative damage.

Extracellular superoxide dismutase is present in secretory vesicles of human neutrophils and released upon stimulation

Extracellular superoxide dismutase (EC-SOD) is an antioxidant enzyme present in the extracellular matrix (ECM), where it provides protection against oxidative degradation of matrix constituents including type I collagen and hyaluronan. The enzyme is known to associate with macrophages and polymorphonuclear leukocytes (neutrophils) and increasing evidence supports a role for EC-SOD in the development of an inflammatory response. Here we show that human EC-SOD is present at the cell surface of isolated neutrophils as well as stored within secretory vesicles. Interestingly, we find that EC-SOD mRNA is absent throughout neutrophil maturation indicating that the protein is synthesized by other cells and subsequently endocytosed by the neutrophil. When secretory vesicles were mobilized by neutrophil stimulation using formyl-methionyl-leucyl-phenylalanine (fMLF) or phorbol 12-myristate 13-acetate (PMA), the protein was released into the extracellular space and found to associate with DNA released from stimulated cells. The functional consequences were evaluated by the use of neutrophils isolated from wild-type and EC-SOD KO mice, and showed that EC-SOD release significantly reduce the level of superoxide in the extracellular space, but does not affect the capacity to generate neutrophil extracellular traps (NETs). Consequently, our data signifies that EC-SOD released from activated neutrophils affects the redox conditions of the extracellular space and may offer protection against highly reactive oxygen species such as hydroxyl radicals otherwise generated as a result of respiratory burst activity of activated neutrophils.

Acute exposure to air pollution particulate matter aggravates experimental myocardial infarction in mice by potentiating cytokine secretion from lung macrophages

Clinical, but not experimental evidence has suggested that air pollution particulate matter (PM) aggravates myocardial infarction (MI). Here, we aimed to describe mechanisms and consequences of PM exposure in an experimental model of MI. C57BL/6J mice were challenged with a PM surrogate (Residual Oil Fly Ash, ROFA) by intranasal installation before MI was induced by permanent ligation of the left anterior descending coronary artery. Histological analysis of the myocardium 7 days after MI demonstrated an increase in infarct area and enhanced inflammatory cell recruitment in ROFA-exposed mice. Mechanistically, ROFA exposure increased the levels of the circulating pro-inflammatory cytokines TNF-α, IL-6, and MCP-1, activated myeloid and endothelial cells, and enhanced leukocyte recruitment to the peritoneal cavity and the vascular endothelium. Notably, these effects on endothelial cells and circulating leukocytes could be reversed by neutralizing anti-TNF-α treatment. We identified alveolar macrophages as the primary source of elevated cytokine production after PM exposure. Accordingly, in vivo depletion of alveolar macrophages by intranasal clodronate attenuated inflammation and cell recruitment to infarcted tissue of ROFA-exposed mice. Taken together, our data demonstrate that exposure to environmental PM induces the release of inflammatory cytokines from alveolar macrophages which directly worsens the course of MI in mice. These findings uncover a novel link between air pollution PM exposure and inflammatory pathways, highlighting the importance of environmental factors in cardiovascular disease.

Paradoxical Roles of Antioxidant Enzymes: Basic Mechanisms and Health Implications

Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are generated from aerobic metabolism, as a result of accidental electron leakage as well as regulated enzymatic processes. Because ROS/RNS can induce oxidative injury and act in redox signaling, enzymes metabolizing them will inherently promote either health or disease, depending on the physiological context. It is thus misleading to consider conventionally called antioxidant enzymes to be largely, if not exclusively, health protective. Because such a notion is nonetheless common, we herein attempt to rationalize why this simplistic view should be avoided. First we give an updated summary of physiological phenotypes triggered in mouse models of overexpression or knockout of major antioxidant enzymes. Subsequently, we focus on a series of striking cases that demonstrate "paradoxical" outcomes, i.e., increased fitness upon deletion of antioxidant enzymes or disease triggered by their overexpression. We elaborate mechanisms by which these phenotypes are mediated via chemical, biological, and metabolic interactions of the antioxidant enzymes with their substrates, downstream events, and cellular context. Furthermore, we propose that novel treatments of antioxidant enzyme-related human diseases may be enabled by deliberate targeting of dual roles of the pertaining enzymes. We also discuss the potential of "antioxidant" nutrients and phytochemicals, via regulating the expression or function of antioxidant enzymes, in preventing, treating, or aggravating chronic diseases. We conclude that "paradoxical" roles of antioxidant enzymes in physiology, health, and disease derive from sophisticated molecular mechanisms of redox biology and metabolic homeostasis. Simply viewing antioxidant enzymes as always being beneficial is not only conceptually misleading but also clinically hazardous if such notions underpin medical treatment protocols based on modulation of redox pathways.

Selective TNF-α targeting with infliximab attenuates impaired oxygen metabolism and contractile function induced by an acute exposure to air particulate matter

Inflammation plays a central role in the onset and progression of cardiovascular diseases associated with the exposure to air pollution particulate matter (PM). The aim of this work was to analyze the cardioprotective effect of selective TNF-α targeting with a blocking anti-TNF-α antibody (infliximab) in an in vivo mice model of acute exposure to residual oil fly ash (ROFA). Female Swiss mice received an intraperitoneal injection of infliximab (10 mg/kg body wt) or saline solution, and were intranasally instilled with a ROFA suspension (1 mg/kg body wt). Control animals were instilled with saline solution and handled in parallel. After 3 h, heart O2 consumption was assessed by high-resolution respirometry in left ventricle tissue cubes and isolated mitochondria, and ventricular contractile reserve and lusitropic reserve were evaluated according to the Langendorff technique. ROFA instillation induced a significant decrease in tissue O2 consumption and active mitochondrial respiration by 32 and 31%, respectively, compared with the control group. While ventricular contractile state and isovolumic relaxation were not altered in ROFA-exposed mice, impaired contractile reserve and lusitropic reserve were observed in this group. Infliximab pretreatment significantly attenuated the decrease in heart O2 consumption and prevented the decrease in ventricular contractile and lusitropic reserve in ROFA-exposed mice. Moreover, infliximab-pretreated ROFA-exposed mice showed conserved left ventricular developed pressure and cardiac O2 consumption in response to a β-adrenergic stimulus with isoproterenol. These results provides direct evidence linking systemic inflammation and altered cardiac function following an acute exposure to PM and contribute to the understanding of PM-associated cardiovascular morbidity and mortality.

Chemical composition modulates the adverse effects of particles on the mucociliary epithelium

OBJECTIVE

We compared the adverse effects of two types of real ambient particles; i.e., total suspended particles from an electrostatic precipitator of a steel mill and fine air particles from an urban ambient particulate matter of 2.5 µm, on mucociliary clearance.

METHOD

Mucociliary function was quantified by mucociliary transport, ciliary beating frequency and the amount of acid and neutral mucous in epithelial cells through morphometry of frog palate preparations. The palates were immersed in one of the following solutions: total suspended particles (0.1 mg/mL), particulate matter 2.5 µm 0.1 mg/mL (PM0.1) or 3.0 mg/mL (PM3.0) and amphibian Ringer's solution (control). Particle chemical compositions were determined by X-ray fluorescence and gas chromatography/mass spectrometry.

RESULTS

Exposure to total suspended particles and PM3.0 decreased mucociliary transport. Ciliary beating frequency was diminished by total suspended particles at all times during exposure, while particulate matter of 2.5 µm did not elicit changes. Particulate matter of 2.5 µm reduced epithelial mucous and epithelium thickness, while total suspended particles behaved similarly to the control group. Total suspended particles exhibited a predominance of Fe and no organic compounds, while the particulate matter 2.5 µm contained predominant amounts of S, Fe, Si and, to a lesser extent, Cu, Ni, V, Zn and organic compounds.

CONCLUSION

Our results showed that different compositions of particles induced different airway epithelial responses, emphasizing that knowledge of their individual characteristics may help to establish policies aimed at controlling air pollution.

Functional and morphological olfactory bulb modifications in mice after vanadium inhalation

Neurodegenerative disorders, such as Parkinson's and Alzheimer's diseases, have olfaction impairment. These pathologies have also been linked to environmental pollutants. Vanadium is a pollutant, and its toxic mechanisms are related to the production of oxidative stress. In this study, we evaluated the effects of inhaled vanadium on olfaction, the olfactory bulb antioxidant, through histological and ultrastructural changes in granule cells. Mice in control group were made to inhale saline; the experimental group inhaled 0.02-M vanadium pentoxide (V2O5) for 1 hr twice a week for 4 weeks. Animals were sacrificed at 1, 2, 3, and 4 weeks after inhalation. Olfactory function was evaluated by the odorant test. The activity of glutathione peroxidase (GPx) and glutathione reductase (GR) was assayed in olfactory bulbs and processed for rapid Golgi method and ultrastructural analysis. Results show that olfactory function decreased at 4-week vanadium exposure; granule cells showed a decrease in dendritic spine density and increased lipofuscin, Golgi apparatus vacuolation, apoptosis, and necrosis. The activity of GPx and GR in the olfactory bulb was increased compared to that of the controls. Our results demonstrate that vanadium inhalation disturbs olfaction, histology, and the ultrastructure of the granule cells that might be associated with oxidative stress, a risk factor in neurodegenerative diseases.

A common polymorphism in extracellular superoxide dismutase affects cardiopulmonary disease risk by altering protein distribution

BACKGROUND

The enzyme extracellular superoxide dismutase (EC-SOD; SOD3) is a major antioxidant defense in lung and vasculature. A nonsynonomous single-nucleotide polymorphism in EC-SOD (rs1799895) leads to an arginine to glycine amino acid substitution at position 213 (R213G) in the heparin-binding domain. In recent human genetic association studies, this single-nucleotide polymorphism attenuates the risk of lung disease, yet paradoxically increases the risk of cardiovascular disease.

METHODS AND RESULTS

Capitalizing on the complete sequence homology between human and mouse in the heparin-binding domain, we created an analogous R213G single-nucleotide polymorphism knockin mouse. The R213G single-nucleotide polymorphism did not change enzyme activity, but shifted the distribution of EC-SOD from lung and vascular tissue to extracellular fluid (eg, bronchoalveolar lavage fluid and plasma). This shift reduces susceptibility to lung disease (lipopolysaccharide-induced lung injury) and increases susceptibility to cardiopulmonary disease (chronic hypoxic pulmonary hypertension).

CONCLUSIONS

We conclude that EC-SOD provides optimal protection when localized to the compartment subjected to extracellular oxidative stress: thus, the redistribution of EC-SOD from the lung and pulmonary circulation to the extracellular fluids is beneficial in alveolar lung disease but detrimental in pulmonary vascular disease. These findings account for the discrepant risk associated with R213G in humans with lung diseases compared with cardiovascular diseases.

Pulmonary inflammation and cell death in mice after acute exposure to air particulate matter from an industrial region of Buenos Aires

Epidemiological studies have shown that air particulate matter (PM) can increase respiratory morbidity and mortality being the lungs the main target organ to PM body entrance. Even more, several in vivo and in vitro studies have shown that air PM has a wide toxicity spectra depending among other parameters, on its size, morphology, and chemical composition. The Reconquista River is the second most polluted river from Buenos Aires, and people living around its basin are constantly exposed to its contaminated water, soil and air. However, the air PM from the Reconquista River (RR-PMa) has not been characterized, and its biological impact on lung has yet not been assessed. Therefore, the present investigation was undertaken to study (1) RR-PMa morphochemical characteristic and (2) RR-PMa lung acute effects after intranasal instillation exposure through the analysis of three end points: oxidative stress, inflammation, and apoptosis. A single acute exposure of RR-PMa (1 mg/kg body weight) after 24 h caused significant (p < 0.05) enrichment in bronchoalveolar total cell number and polymorphonuclear (PNM) fraction, superoxide anion generation, production of pro-inflammatory cytokines TNF-α and IL-6, and induction of apoptosis. It was also observed that in lung homogenates, none of the antioxidant enzymes assayed showed differences between exposed RR-PMa and control mice. These data demonstrate that air PM from the Reconquista River induce lung oxidative stress, inflammation, and cell death therefore represents a potential hazard to human health.

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

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

NANOMATERIALS FOR PROTEIN MEDIATED THERAPY AND DELIVERY

There has been a significant amount of research done on liposomes and nanoparticles as drug carriers for protein drugs. Proteins and enzymes have been used both as targeting moieties and for their therapeutic potential. High specificity and rapid reaction rates make proteins and enzymes excellent candidates for therapeutic treatment, but some limitations exist. Many of these limitations can be addressed by a well studied nanotechnology based delivery system. Such a system can provide a medium for delivery, stabilization of the drugs, and enable site specific accumulation of drugs. Nanomedicines such as these have great potential to revolutionize the pharmaceutical industry and improve healthcare worldwide.

Impaired cardiac mitochondrial function and contractile reserve following an acute exposure to environmental particulate matter

BACKGROUND

It has been suggested that mitochondrial function plays a central role in cardiovascular diseases associated with particulate matter inhalation. The aim of this study was to evaluate this hypothesis, with focus on cardiac O2 and energetic metabolism, and its impact over cardiac contractility.

METHODS

Swiss mice were intranasally instilled with either residual oil fly ash (ROFA) (1.0 mg/kg body weight) or saline solution. After 1, 3 or 5 h of exposure, O2 consumption was evaluated in heart tissue samples. Mitochondrial respiration, respiratory chain complexes activity, membrane potential and ATP content and production rate were assessed in isolated mitochondria. Cardiac contractile reserve was evaluated according to the Langendorff technique.

RESULTS

Three hours after ROFA exposure, tissue O2 consumption was significantly decreased by 35% (from 1180 +/- 70 to 760 +/- 60 ng-at O/min g tissue), as well as mitochondrial rest (state 4) and active (state 3) respiration, by 30 and 24%, respectively (control state 4: 88 +/- 5 ng-at O/min mg protein; state 3: 240 +/- 20 ng-at O/min mg protein). These findings were associated with decreased complex II activity, mitochondrial depolarization and deficient ATP production. Even though basal contractility was not modified (control: 75 +/- 5 mm Hg), isolated perfused hearts failed to properly respond to isoproterenol in ROFA-exposed mice. Tissue O2 consumption rates positively correlated with cardiac contractile state in controls (r2 = 0.8271), but not in treated mice (r2 = 0.1396).

GENERAL SIGNIFICANCE

The present results show an impaired mitochondrial function associated with deficient cardiac contractility, which could represent an early cardiovascular alteration after the exposure to environmental particulate matter.

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).

Extracellular superoxide dismutase inhibits innate immune responses and clearance of an intracellular bacterial infection

Reactive oxygen species and reactive nitrogen species play important roles during immune responses to bacterial pathogens. Extracellular superoxide dismutase (ecSOD) regulates extracellular concentrations of reactive oxygen species and reactive nitrogen species and contributes to tissue protection during inflammatory insults. The participation of ecSOD in immune responses seems therefore intuitive, yet is poorly understood. In the current study, we used mice with varying levels of ecSOD activity to investigate the involvement of this enzyme in immune responses against Listeria monocytogenes. Surprisingly, our data demonstrate that despite enhanced neutrophil recruitment to the liver, ecSOD activity negatively affected host survival and bacterial clearance. Increased ecSOD activity was accompanied by decreased colocalization of neutrophils with bacteria, as well as increased neutrophil apoptosis, which reduced overall and neutrophil-specific TNF-α production. Liver leukocytes from mice lacking ecSOD produced equivalent NO· compared with liver leukocytes from mice expressing ecSOD. However, during infection, there were higher levels of peroxynitrite (NO(3)·(-)) in livers from mice lacking ecSOD compared with livers from mice expressing ecSOD. Neutrophil depletion studies revealed that high levels of ecSOD activity resulted in neutrophils with limited protective capacity, whereas neutrophils from mice lacking ecSOD provided superior protection compared with neutrophils from wild-type mice. Taken together, our data demonstrate that ecSOD activity reduces innate immune responses during bacterial infection and provides a potential target for therapeutic intervention.

Mouse Models of Oxidative Stress Indicate a Role for Modulating Healthy Aging

Aging is a complex process that affects every major system at the molecular, cellular and organ levels. Although the exact cause of aging is unknown, there is significant evidence that oxidative stress plays a major role in the aging process. The basis of the oxidative stress hypothesis is that aging occurs as a result of an imbalance between oxidants and antioxidants, which leads to the accrual of damaged proteins, lipids and DNA macromolecules with age. Age-dependent increases in protein oxidation and aggregates, lipofuscin, and DNA mutations contribute to age-related pathologies. Many transgenic/knockout mouse models over expressing or deficient in key antioxidant enzymes have been generated to examine the effect of oxidative stress on aging and age-related diseases. Based on currently reported lifespan studies using mice with altered antioxidant defense, there is little evidence that oxidative stress plays a role in determining lifespan. However, mice deficient in antioxidant enzymes are often more susceptible to age-related disease while mice overexpressing antioxidant enzymes often have an increase in the amount of time spent without disease, i.e., healthspan. Thus, by understanding the mechanisms that affect healthy aging, we may discover potential therapeutic targets to extend human healthspan.

Divergent electrocardiographic responses to whole and particle-free diesel exhaust inhalation in spontaneously hypertensive rats

Diesel exhaust (DE) is a major contributor to traffic-related fine particulate matter (PM)(2.5). Although inroads have been made in understanding the mechanisms of PM-related health effects, DE's complex mixture of PM, gases, and volatile organics makes it difficult to determine how the constituents contribute to DE's effects. We hypothesized that exposure to particle-filtered DE (fDE; gases alone) will elicit less cardiac effects than whole DE (wDE; particles plus gases). In addition, we hypothesized that spontaneously hypertensive (SH) rats will be more sensitive to the electrocardiographic effects of DE exposure than Wistar Kyoto rats (WKY; background strain with normal blood pressure). SH and WKY rats, implanted with telemeters to monitor electrocardiogram and heart rate (HR), were exposed once for 4 h to 150 μg/m(3) or 500 μg/m(3) of wDE (gases plus PM) or fDE (gases alone) DE, or filtered air. Exposure to fDE, but not wDE, caused immediate electrocardiographic alterations in cardiac repolarization (ST depression) and atrioventricular conduction block (PR prolongation) as well as bradycardia in SH rats. Exposure to wDE, but not fDE, caused postexposure ST depression and increased sensitivity to the pulmonary C fiber agonist capsaicin in SH rats. The only notable effect of DE exposure in WKY rats was a decrease in HR. Taken together, hypertension may predispose to the potential cardiac effects of DE and components of DE may have divergent effects with some eliciting immediate irritant effects (e.g., gases), whereas others (e.g., PM) trigger delayed effects potentially via separate mechanisms.

Influence of propofol and volatile anaesthetics on the inflammatory response in the ventilated lung

BACKGROUND

The immunomodulatory effects of volatile anaesthetics in vitro and the protective effect of propofol in lung injury spurred us to study the effects of volatile anaesthetics and propofol on lung tissue in vivo.

METHODS

Twenty-seven pigs were randomized to 4-h general anaesthesia with propofol (8 mg/kg/h, group P, n=9), sevoflurane [minimum alveolar concentration (MAC)=1.0, group S, n=9) or desflurane (MAC=1.0, group D, n=9). Four healthy animals served as the no-ventilation group. Bronchoalveolar lavage fluid (BALF) was obtained to measure the cell counts, platelet-activating factor acetylhydrolase (PAF-AcH), phospholipase A(2) (PLA(2)) and superoxide dismutase (SOD) activity. Lung tissues were evaluated histologically and for caspase-3 expression.

RESULTS

Volatile anaesthetics reduced PAF-AcH levels without affecting PLA(2) activity and resulted in decreased alveolar macrophage and increased lymphocyte counts in BALF (sevoflurane: 29 ± 23%; desflurane: 26 ± 6%, both P<0.05 compared with 4 ± 2% in the no-ventilation group). These findings were accompanied by atelectasis and inflammatory cells' infiltration in the inhalational anaesthetics groups. Also, sevoflurane reduced SOD activity and both sevoflurane and desflurane induced significant caspase-3 expression. In contrast, propofol resulted in a minor degree of inflammation and preserved BALF cells' composition without triggering apoptosis.

CONCLUSION

Halogenated anaesthetics seem to trigger an immune lymphocytic response in the lung, inducing significant apoptosis and impairment of PAF-AcH. In contrast, propofol preserves anti-inflammatory and anti-oxidant defences during mechanical ventilation, thus preventing the emergence of apoptosis.

Extracellular superoxide dismutase polymorphism in mice: Allele-specific effects on phenotype

Extracellular superoxide dismutase (ecSOD) protects the extracellular matrix from oxidative stress. We previously reported a new allele for ecSOD, expressed in 129P3/J mice (129), which differs from the wild type (wt), expressed in C57BL/6J and other strains, by two amino acid substitutions and a 10-bp deletion in the 3' UTR of the mRNA (A. Pierce et al., 2003, Arterioscler. Thromb. Vasc. Biol.23:1820-1825). The newly discovered allele is associated with a phenotype of significantly increased circulating and heparin-releasable enzyme activities and levels. To examine the properties of the two forms of ecSOD in an identical environment we generated, by extensive backcrossing of ecSOD heterozygous progeny to C57BL/6J females, a congenic C57 strain with the 129 (or wt) allele of ecSOD. These mice are homozygous for nearly 5000 SNPs across all chromosomes, as determined by the Affymetrix Parallele Mouse 5K SNP panel. This study describes the generation of the congenic mice (genetically >99.8% identical) and their ecSOD phenotype. The congenic mouse plasma ecSOD activity before and after heparin administration recapitulates the differences reported in the founder mice. Tissue enzyme distribution is similar in both congenic groups, although the 129 allele is associated with higher levels of enzyme expression despite lower levels of enzyme mRNA. In these characteristics the phenotype is allele driven, with little impact from the rest of the genome. The congenic mice carrying the 129 allele have mRNA levels that are in between those in the founder 129P3/J and C57BL/6J strains. We conclude that the ecSOD phenotype in most aspects of enzyme expression is allele driven, with the exception of tissue mRNA levels, for which a significant contribution by the surrounding (host) genome is observed. These results also suggest potential allele-specific differences in the regulation of ecSOD synthesis and intracellular processing/secretion of ecSOD, independent of the genotype context. Most importantly, the congenic mice offer an excellent model to examine the regulatory mechanisms of ecSOD expression and the role of ecSOD in various diseases involving oxidative stress.

A new mouse model for temporal- and tissue-specific control of extracellular superoxide dismutase

The extracellular isoform of superoxide dismutase (EC-SOD, Sod3) plays a protective role against various diseases and injuries mediated by oxidative stress. To investigate the pathophysiological roles of EC-SOD, we generated tetracycline-inducible Sod3 transgenic mice and directed the tissue-specific expression of transgenes by crossing Sod3 transgenic mice with tissue-specific transactivator transgenics. Double transgenic mice with liver-specific expression of Sod3 showed increased EC-SOD levels predominantly in the plasma as the circulating form, whereas double transgenic mice with neuronal-specific expression expressed higher levels of EC-SOD in hippocampus and cortex with intact EC-SOD as the dominant form. EC-SOD protein levels also correlated well with increased SOD activities in double transgenic mice. In addition to enabling tissue-specific expression, the transgene expression can be quickly turned on and off by doxycycline supplementation in the mouse chow. This mouse model, thus, provides the flexibility for on-off control of transgene expression in multiple target tissues.

Superoxide dismutase 3, extracellular (SOD3) variants and lung function

Polymorphisms in Superoxide dismutase 3, extracellular (SOD3) have been associated with reduced lung function and susceptibility to chronic obstructive pulmonary disease (COPD) in adults. Previously, we identified SOD3 as a contributing factor to altered ventilation efficiency (dead space volume/total lung capacity) in mice. Because SOD3 protects the extracellular matrix of the lung, we hypothesized that SOD3 variants also may influence postnatal lung function development. In this study, SOD3 transcript and protein localization were examined in mouse strains with differing ventilation efficiency [C3H/HeJ (high), JF1/Msf (low)] during postnatal lung development. Compared with C3H/HeJ mice, JF1/Msf mice had Sod3 promoter single nucleotide polymorphisms (SNPs) that could affect transcription factor binding sites and a decline in total lung SOD3 mRNA during postnatal development. In adult JF1/Msf mice, total lung SOD3 activity as well as SOD3 transcript and protein in airway epithelial and alveolar type II cells and the associated matrix decreased. In children (n = 1,555; age 9-11 yr), two common SOD3 SNPs, one located in the promoter region [C/T affecting a predicted aryl hydrocarbon receptor-xenobiotic response element (AhR-XRE) binding motif] and the other in exon 2 (Thr/Ala missense mutation), were associated with decreased forced expiratory volume in 1 s (FEV(1)), and the promoter SNP was associated with decreased maximal expiratory flow at 25% volume (MEF(25)). In vitro, a SOD3 promoter region-derived oligonucleotide containing the C variant was more effective in competing with the nuclear protein-binding capacity of a labeled probe than that containing the T variant. Along with the previous associated risk of lung function decline in COPD, these findings support a possible role of SOD3 variants in determining lung function in children.

Extracellular superoxide dismutase haplotypes are associated with acute lung injury and mortality

RATIONALE

Extracellular superoxide dismutase (EC-SOD) is a potent antioxidant that plays an important role in controlling oxidant-mediated stress and inflammation. High levels of EC-SOD are found in the lung. Acute lung injury (ALI) frequently occurs in patients with infection, and levels of EC-SOD have been shown to modulate severity of lung injury in transgenic animal models of endotoxemia-induced ALI. An R213G single nucleotide polymorphism (SNP) has been shown to alter levels of EC-SOD and patient outcomes in chronic obstructive pulmonary disease (COPD) and ischemic heart disease.

OBJECTIVES

To determine genetic variation in the promoter and EC-SOD gene and to examine whether EC-SOD haplotype blocks are associated with clinical outcomes.

METHODS

We sequenced the EC-SOD promoter and gene to determine genetic variation and linkage disequilibrium (LD) patterns in a European American population. Two separate patient populations with infection-associated ALI were also evaluated to determine whether EC-SOD haplotypes were associated with clinical outcomes.

MEASUREMENTS AND MAIN RESULTS

Sequencing resulted in the identification of 28 SNPs with relatively strong LD and 1 block consisting of 4691-5321-5360-5955-5982. This specific block was shown to be protective in two separate patient populations with infection associated ALI. In particular, patients with a GCCT haplotype had a reduced risk of time on the ventilator and mortality.

CONCLUSIONS

These results indicate that a GCCT haplotype may reduce inflammation in the lung, thereby decreasing the severity of lung injury and ultimately protecting patients from mortality associated with infection-induced ALI.

The effect of supplementation with omega-3 polyunsaturated fatty acids on markers of oxidative stress in elderly exposed to PM(2.5)

BACKGROUND

The mechanisms of particulate matter (PM)-induced health effects are believed to involve inflammation and oxidative stress. Increased intake of omega-3 polyunsaturated fatty acids (n-3 PUFA) appears to have anti-inflammatory effects.

OBJECTIVE

As part of a trial to evaluate whether n-3 PUFA supplementation could protect against the cardiac alterations linked to PM exposure, we measured biomarkers of response to oxidative stimuli [copper/zinc (Cu/Zn) superoxide dismutase (SOD) activity, lipoperoxidation (LPO) products, and reduced glutathione (GSH)] and evaluated the impact of supplementation on plasma levels.

METHODS

We recruited residents from a nursing home in Mexico City chronically exposed to PM < or = 2.5 microm in aerodynamic diameter (PM(2.5)) and followed them from 26 September 2001 to 10 April 2002. We randomly assigned subjects in a double-blind fashion to receive either fish oil (n-3 PUFA) or soy oil. We measured PM(2.5) levels indoors at the nursing home, and measured Cu/Zn SOD activity, LPO products, and GSH at different times during presupplementation and supplementation phases.

RESULTS

Supplementation with either fish or soy oil was related to an increase of Cu/Zn SOD activity and an increase in GSH plasma levels, whereas exposure to indoor PM(2.5) levels was related to a decrease in Cu/Zn SOD activity and GSH plasma levels.

CONCLUSION

Supplementation with n-3 PUFA appeared to modulate the adverse effects of PM(2.5) on these biomarkers, particularly in the fish oil group. Supplementation with n-3 PUFA could modulate oxidative response to PM(2.5) exposure.

Superoxide dismutase 3 polymorphism associated with reduced lung function in two large populations

RATIONALE

Superoxide dismutase (SOD) 3 inhibits oxidative fragmentation of lung matrix components collagen I, hyaluronan, and heparan sulfate. Inherited change in SOD3 expression or function could affect lung matrix homeostasis and influence pulmonary function.

OBJECTIVES

To identify novel SOD3 polymorphisms that are associated with lung function or chronic obstructive pulmonary disease (COPD).

METHODS

Resequencing of 182 individuals identified two novel polymorphisms, E1 (rs8192287) and I1 (rs8192288), in a conserved region of the SOD3 gene of potential relationship to lung function. We next genotyped 9,093 individuals from the Copenhagen City Heart Study for the polymorphisms and recorded spirometry, and admissions and deaths due to COPD during 26-year follow-up. Finally, we validated our findings in a cross-sectional analysis of 35,635 individuals from the Copenhagen General Population Study.

MEASUREMENTS AND MAIN RESULTS

Genotyping the Copenhagen City Heart Study identified 35 E1/I1 homozygotes, 1,050 heterozygotes, and 8,008 noncarriers (Hardy-Weinberg equilibrium: P = 0.93). Using quadruple lung function measurements, we found that E1/I1 homozygotes had 7% lower FVC % predicted (P = 0.006) and 4% lower FEV(1) % predicted (P = 0.12) compared with noncarriers. In the Copenhagen General Population Study, E1/I1 homozygotes also had lower FVC % predicted than noncarriers (P = 0.03), confirming an association between E1/I1 genotype and reduced lung function. E1/I1 homozygotes had adjusted hazard ratios for COPD hospitalization and COPD mortality of 2.5 (95% confidence interval, 1.0-5.9) and 3.7 (95% confidence interval, 0.9-15), respectively; the results were independent of influence from the R213G allele of the SOD3 gene.

CONCLUSIONS

We identified two novel polymorphisms in a conserved region of the SOD3 gene and show that individuals that are homozygous for these polymorphisms have reduced FVC % predicted in two large, population-based studies.

Oxidant-antioxidant imbalance as a potential contributor to the progression of human pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is the most common idiopathic interstitial pneumonia. IPF is a disease with poor prognosis and an aggressive nature, and poses major challenges to clinicians. Thus, a large part of research in the area has focused on the pathogenesis on IPF. Characteristic features in IPF include fibrotic lesions devoid of inflammatory cell infiltrates. There are experimental models of lung fibrosis (e.g., bleomycin-induced fibrosis), but they typically contain a prominent inflammatory pattern in the lung, which leads to relatively diffuse lung fibrosis. Nonetheless, experimental models have provided important information about the progression and pathways contributing to the lung fibrosis, including activation of transforming growth factor beta (TGF-beta). Both patient material and experimental models of lung fibrosis have displayed marked elevation of several markers of oxidant burden and signs for disturbed antioxidant/oxidant balance. Several studies also suggest that reactive oxygen species can cause activation of growth-regulatory cytokines, including TGF-beta. In addition, there are indications that endogenous and exogenous antioxidants/redox modulators can influence fibrogenesis, protect the lung against fibrosis, and prevent its progression. Factors that restore the antioxidant capacity and prevent sustained activation of growth-regulatory cytokines may have a therapeutic role in IPF.

Inhibition of the TPA-induced cutaneous inflammation and hyperplasia by EC-SOD

This study reports the roles of extracellular superoxide dismutase (EC-SOD) in the cutaneous inflammation and hyperplasia with 12-O-tetradecanoylphorbol-3-acetate (TPA) application in EC-SOD transgenic mice (Tg EC-SOD). Topical double TPA treatment induced the various inflammatory changes including the epidermal thickness, elevated the PCNA-labeling index, the edema formation, and increased production of hydrogen peroxide (H2O2) in wild type mice (WT). These changes were markedly suppressed in TPA-treated Tg EC-SOD. The expressions of the inflammatory cytokines, IL-1alpha and IL-1beta, were reduced in the TPA-treated Tg EC-SOD compared with those in TPA-treated WT. The expression of IL-1alpha was significantly increased in the skin of TPA-treated WT, especially in the basal and suprabasal layers, but it was restricted focally in basal layer of the skin of TPA-treated Tg EC-SOD. The number of infiltrating inflammatory cells and the IL-1beta expressing cells was obviously reduced in TPA-treated Tg EC-SOD in comparison with TPA-treated WT. The result suggests that EC-SOD might play an important role in the suppression of TPA-induced cutaneous inflammation and epidermal hyperplasia by regulating the expression of IL-1alpha and IL-1beta, although the mechanisms remain to be elucidated.

Functional variants of antioxidant genes in smokers with COPD and in those with normal lung function

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is predominantly the consequence of chronic smoking exposure, but its development may be influenced by genetic variants that affect lung remodelling, inflammation, and defence from oxidant stress. A study was undertaken to determine whether genetic variants within genes encoding the antioxidant enzymes superoxide dismutase (SOD) and catalase may be associated with the development of impaired lung function.

METHODS

In a case-control study, the allele and genotype frequencies of functional polymorphisms from SOD1 (CuZnSOD), SOD2 (MnSOD), SOD3 (extracellular SOD), and catalase (CAT) were compared in chronic smokers with normal lung function (resistant smokers) and in those with COPD.

RESULTS

Significantly higher frequencies of the G allele and CG/GG genotype of the 213 SOD3 polymorphism were found in resistant smokers (odds ratios (ORs) 4.3 (95% CI 1.5 to 13.3) and 4.2, 95% CI 1.4 to 13.3), Bonferroni corrected p = 0.02 and p = 0.02, respectively) than in those with COPD. There were no differences between the COPD and resistant smokers for the SOD1, SOD2, or CAT polymorphisms tested.

CONCLUSIONS

The 213Gly variant of the SOD3 gene may, through antioxidant or anti-inflammatory effects, confer a degree of resistance in some smokers to the development of COPD.

Inflammatory cells as a source of airspace extracellular superoxide dismutase after pulmonary injury

Extracellular superoxide dismutase (EC-SOD) is an antioxidant abundant in the lung. Previous studies demonstrated depletion of lung parenchymal EC-SOD in mouse models of interstitial lung disease coinciding with an accumulation of EC-SOD in airspaces. EC-SOD sticks to the matrix by a proteolytically sensitive heparin-binding domain; therefore, we hypothesized that interstitial inflammation and matrix remodeling contribute to proteolytic redistribution of EC-SOD from lung parenchyma into the airspaces. To determine if inflammation limited to airspaces leads to EC-SOD redistribution, we examined a bacterial pneumonia model. This model led to increases in airspace polymorphonuclear leukocytes staining strongly for EC-SOD. EC-SOD accumulated in airspaces at 24 h without depletion of EC-SOD from lung parenchyma. This led us to hypothesize that airspace EC-SOD was released from inflammatory cells and was not a redistribution of matrix EC-SOD. To test this hypothesis, transgenic mice with lung-specific expression of human EC-SOD were treated with asbestos or bleomycin to initiate an interstitial lung injury. In these studies, EC-SOD accumulating in airspaces was entirely the mouse isoform, demonstrating an extrapulmonary source (inflammatory cells) for this EC-SOD. We also demonstrate that EC-SOD knockout mice possess greater lung inflammation in response to bleomycin and bacteria when compared with wild types. We conclude that the source of accumulating EC-SOD in airspaces in interstitial lung disease is inflammatory cells and not the lung and that interstitial processes such as those found in pulmonary fibrosis are required to remove EC-SOD from lung matrix.

Anti-oxidants reduce the acute adverse effects of residual oil fly ash on the frog palate mucociliary epithelium

There is evidence indicating that oxidants play a pivotal role in determining air pollution-dependent lung injury. In the present study we explored the role of oxidants present in ambient particles in causing damage to the mucociliary epithelium. We explored the protective effects of pretreatment with three substances (n-propyl gallate, DL-alpha-tocopherol acetate, and EDTA) on the frog palate exposed to residual oil fly ash (ROFA). The parameters analyzed were mucociliary transport (MCT) and ciliary beating frequency (CBF) after 0, 10, 20, 30, 60, and 120 min of exposure. MCT was decreased significantly by ROFA (P < 0.001), with a significant interaction effect (P = 0.02) between the duration of exposure and treatment with antioxidants. The inhibitory effects on MCT of the substances tested were significantly different (P = 0.002); vitamin E was similar to control (Ringer) and different from all other groups. CBF showed no significant effect of duration of exposure (P = 0.465), but a significant interaction between duration of exposure and treatments was observed (P = 0.011). Significant differences were detected among treatments (P < 0.001), with ROFA and n-propyl gallate at concentrations of 50 microM presenting a short-lived increase in CBF, which was not observed in the remaining groups. The results showed that both MCT and CBF were affected within a short period (100 min) of exposure to ROFA and that the presence of antioxidant substances, such as vitamin E (4 mg/mL) and n-propyl gallate (300 microM), protected against the mucociliary impairment induced by ROFA on the frog palate.

Inhibition of iNOS attenuates skeletal muscle reperfusion injury in extracellular superoxide dismutase knockout mice

Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are closely involved in the mechanism of skeletal muscle ischemia/reperfusion (I/R) injury. This study was designed to determine the effects of inducible nitric oxide synthase (iNOS) inhibitor 1400 W on the reperfused cremaster muscle in extracellular super-oxide dismutase knockout (EC-SOD(-/-)) mice. The muscle was exposed to 4.5 h of ischemia, followed by 90 min of reperfusion. Mice received either 3 mg/kg of 1400 W or the same amount of phosphate-buffered saline (PBS, as a control) subcutaneously at 10 min before the start of reperfusion. 1400 W treatment markedly improved the recovery speed of vessel diameter and blood flow in the reperfused cremaster muscle of EC-SOD(-/-) mice compared to controls. Histological examination showed reduced edema in the interstitial space and muscle fiber, and reduced density of nitrotyrosine (a marker of total peroxi-nitrate (ONOO(-)) level) in 1400 W-treated muscles compared to controls. Our results suggest that iNOS and ONOO(-) products are involved in skeletal muscle I/R injury. Reduced I/R injury by using selective inhibition of iNOS perhaps works by limiting cytotoxic ONOO(-) generation, a reaction product of nitric oxide (NO) and super-oxide anion (O(2) (-)). Thus, inhibition of iNOS appears to be a treatment strategy for reducing clinical I/R injury.

Neither neutrophils nor reactive oxygen species contribute to tissue damage during Pneumocystis pneumonia in mice

Neutrophils are implicated in the damage of lung tissue in many disease states, including infectious diseases and environmental insults. These effects may be due to oxidative or nonoxidative functions of the neutrophil or both. We examined the role of neutrophils in pulmonary damage during infection with the opportunistic fungal pathogen Pneumocystis sp. in four mouse models of neutrophil dysfunction. These were (i) a knockout of the gp91(phox) component of NADPH oxidase, in which reactive oxygen species (ROS) production is greatly reduced; (ii) a double knockout of gp91(phox) and inducible nitric oxide synthase, in which ROS and nitric oxide production is greatly decreased; (iii) a knockout of the chemokine receptor CXCR2, in which accumulation of intra-alveolar neutrophils is severely diminished; and (iv) antibody depletion of circulating neutrophils in wild-type mice with the monoclonal antibody RB6. Surprisingly, in each case, indicators of pulmonary damage (respiratory rates, arterial oxygen partial pressures, and intra-alveolar albumin concentrations) were the same in knockout mice and comparable wild-type mice. Therefore, whereas neutrophils are a valid correlative marker of lung damage during Pneumocystis infection, neither neutrophils nor ROS appear to be the causative agent of tissue damage. We also show that there is no difference in Pneumocystis burdens between wild-type and knockout mice, which supports the idea that neutrophils do not have a major role in the clearance of this organism.

Extracellular superoxide dismutase attenuates lipopolysaccharide-induced neutrophilic inflammation

Extracellular superoxide dismutase (EC-SOD) is an abundant antioxidant in the lung and vascular walls. Previous studies have shown that EC-SOD attenuates lung injury in a diverse variety of lung injury models. In this study, we examined the role of EC-SOD in mediating lipopolysaccharide (LPS)-induced lung inflammation. We found that LPS-induced neutrophilic lung inflammation was exaggerated in EC-SOD-deficient mice and diminished in mice that overexpressed EC-SOD specifically in the lung. Similar patterns were seen for bronchoalveolar lavage cytokines, such as tumor necrosis factor-alpha, keratinocyte-derived chemokines, and macrophage inflammatory protein-2 as well as expression of lung intercellular adhesion molecule-1, vascular cell adhesion molecule-1, endothelial cell selectin, and platelet selectin. In a macrophage cell line, EC-SOD inhibited LPS-induced macrophage cytokine release, but did not alter expression of intercellular adhesion molecules in endothelial cells. These results suggest that EC-SOD plays an important role in attenuating the inflammatory response in the lung most likely by decreasing release of proinflammatory cytokines from phagocytes.

ESR investigation of the oxidative damage in lungs caused by asbestos and air pollution particles

Exposure to asbestos and air pollution particles can be associated with increased human morbidity and mortality. However, the molecular mechanism of lung injuries remains unknown. It has been postulated that the in vivo toxicity results from the catalysis of free radical generation. Using electron spin resonance (ESR) in conjunction with the spin trap alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone (4-POBN) we previously investigated in vivo free radical production by rats treated with intratracheal instillation of asbestos (crocidolite fibers) and an emission source air pollution particle (oil fly ash). In this report we compare the effect of two different exposures on the type of free radicals they induce in in vivo animal model. Twenty-four hours after the exposure, ESR spectroscopy of the chloroform extract from lungs of animals exposed to either asbestos or oil fly ash gave a spectrum consistent with a carbon-centered radical adduct (aN = 15.01 G and aH = 2.46 G). To test whether free radical formation occurred in vivo and not in vitro, a number of control experiments were performed. Combinations (both individually and together) of asbestos or oil fly ash and 4-POBN were added to lung homogenate of unexposed rats prior to chloroform extraction. No detectable ESR signal resulted. To exclude the possibility of ex vivo free radical generation, asbestos or oil fly ash was added to lung homogenate of an animal treated with 4-POBN. Also, 4-POBN was added to lung homogenate from rats instilled with asbestos or oil fly ash. Neither system produced radical adducts, indicating that the ESR signal detected in the lung extracts of the treated animals must be produced in vivo and not ex vivo or in vitro. In conclusion, ESR analysis of lung tissue demonstrated that both exposures produce lipid-derived radical metabolites despite their different composition and structure. Analogously, both exposures provide evidence of in vivo enhanced lipid peroxidation. Furthermore, it is concluded that without the presence of a spin-trapping agent, no free radical metabolites could be detected directly by ESR in either exposure.