Urinary Eicosanoid Levels Reflect Allergen and Diesel Exhaust Coexposure and Are Linked to Impaired Lung Function

Eicosanoids are potent regulators of homeostasis and inflammation. Co-exposure to allergen and diesel exhaust (DE) have been shown to lead to eosinophilic inflammation, impaired airflow, and increased airway responsiveness. It is not clear whether eicosanoids mediate the mechanism by which these exposures impair lung function. We conducted a randomized, double-blinded, and four-arm crossover study. Fourteen allergen-sensitized participants were exposed to four conditions: negative control; allergen-alone exposure; DE and allergen coexposure; coexposure with particle-reducing technology applied. Quantitative metabolic profiling of urinary eicosanoids was performed using LC-MS/MS. As expected, allergen inhalation increased eicosanoids. The prostacyclin metabolite 2,3-dinor-6-keto-PGF_1α (PGF_1α, prostaglandin F_1α) increased with coexposure, but particle depletion suppressed this pathway. Individuals with a high genetic risk score demonstrated a greater increase in isoprostane metabolites following coexposure. Causal mediation analyses showed that allergen induced airflow impairment was mediated via leukotriene E₄ and tetranor-prostaglandin D metabolite. Overall, DE exposure did not augment the allergen's effect on urinary eicosanoids, except insofar as variant genotypes conferred susceptibility to the addition of DE in terms of isoprostane metabolites. These findings will add to the body of previous controlled human exposure studies and provide greater insight into how complex environmental exposures in urban air may influence individuals with sensitivity to aeroallergens.

Decreased Fatty Acid Transporter FABP1 and Increased Isoprostanes and Neuroprostanes in the Human Term Placenta: Implications for Inflammation and Birth Weight in Maternal Pre-Gestational Obesity

The rise in prevalence of obesity in women of reproductive age in developed and developing countries might propagate intergenerational cycles of detrimental effects on metabolic health. Placental lipid metabolism is disrupted by maternal obesity, which possibly affects the life-long health of the offspring. Here, we investigated placental lipid metabolism in women with pre-gestational obesity as a sole pregnancy complication and compared it to placental responses of lean women. Open profile and targeted lipidomics were used to assess placental lipids and oxidised products of docosahexaenoic (DHA) and arachidonic acid (AA), respectively, neuroprostanes and isoprostanes. Despite no overall signs of lipid accumulation, DHA and AA levels in placentas from obese women were, respectively, 2.2 and 2.5 times higher than those from lean women. Additionally, a 2-fold increase in DHA-derived neuroprostanes and a 1.7-fold increase in AA-derived isoprostanes were seen in the obese group. These changes correlated with a 70% decrease in placental FABP1 protein. Multivariate analyses suggested that neuroprostanes and isoprostanes are associated with maternal and placental inflammation and with birth weight. These results might shed light on the molecular mechanisms associated with altered placental fatty acid metabolism in maternal pre-gestational obesity, placing these oxidised fatty acids as novel mediators of placental function.

Lipidomic methodologies for biomarkers of chronic inflammation in nutritional research: ω-3 and ω-6 lipid mediators

The evolutionary history of hominins has been characterized by significant dietary changes, which include the introduction of meat eating, cooking, and the changes associated with plant and animal domestication. The Western pattern diet has been linked with the onset of chronic inflammation, and serious health problems including obesity, metabolic syndrome, and cardiovascular diseases. Diets enriched with ω-3 marine PUFAs have revealed additional improvements in health status associated to a reduction of proinflammatory ω-3 and ω-6 lipid mediators. Lipid mediators are produced from enzymatic and non-enzymatic oxidation of PUFAs. Interest in better understanding the occurrence of these metabolites has increased exponentially as a result of the growing evidence of their role on inflammatory processes, control of the immune system, cell signaling, onset of metabolic diseases, or even cancer. The scope of this review has been to highlight the recent findings on: a) the formation of lipid mediators and their role in different inflammatory and metabolic conditions, b) the direct use of lipid mediators as antiinflammatory drugs or the potential of new drugs as a new therapeutic option for the synthesis of antiinflammatory or resolving lipid mediators and c) the impact of nutritional interventions to modulate lipid mediators synthesis towards antiinflammatory conditions. In a second part, we have summarized methodological approaches (Lipidomics) for the accurate analysis of lipid mediators. Although several techniques have been used, most authors preferred the combination of SPE with LC-MS. Advantages and disadvantages of each method are herein addressed, as well as the main LC-MS difficulties and challenges for the establishment of new biomarkers and standardization of experimental designs, and finally to deepen the study of mechanisms involved on the inflammatory response.

Biomarkers of oxidative stress in the fetus and in the newborn

The dynamic field of perinatology entails ever-increasing search for molecular mechanisms of neonatal diseases, especially in the domain of fetal growth and neurodevelopmental outcome. There is an urgent need for new molecular biomarkers, to early identify newborn at high risk for developing diseases and to provide new treatment targets. The interest in biomarkers of oxidative stress in perinatal period have begun to grow in the last century, when it was evidenced the importance of the free radicals generation underlying the various disease conditions. To date, interesting researches have been carried out, representing milestones for implementation of oxidative stress biomarkers in perinatal medicine. Use of a panel of "oxidative stress biomarkers", particularly non protein bound iron, advanced oxidative protein products and isoprostanes, may provide valuable information regarding functional pathways underlying free radical mediated diseases of newborns and their early identification and prevention. Here, we will review recent advances and the current knowledge on the application of biomarkers of oxidative stress in neonatal/perinatal medicine including novel biomarker discovery, defining yet unrecognized biologic therapeutic targets, and linking of oxidative stress biomarkers to relevant standard indices and long-term outcomes.

Oxidative stress - Related spontaneous preterm delivery challenges in causality determination, prevention and novel strategies in reduction of the sequelae

Spontaneous preterm birth (PTB) is one of the major complications of pregnancy and the main cause of neonatal mortality and morbidity. Despite the efforts devoted to the understanding of this obstetrical syndrome and improved medical care, there has been a tendency for the PTB rate to increase in the last decades globally. The costs of the screening for spontaneous PTB, its management, and treatment of the sequelae represent a major burden to the health service economy of high-income countries. In this scenario, it has been widely acknowledged that oxidative stress (OS) plays an important role in the pathogenicity of human disease in wide range of areas of medicine. There is an emerging evidence that an imbalance between pro-and-antioxidants may be associated with spontaneous PTB. However, there are still many controversies on the mechanisms by which OS are involved in the pathogenesis of prematurity. Moreover, the crucial question whether the OS is the cause or consequence of the disease is yet to be answered. The purpose of this article is to briefly summarize the current knowledge and controversies on oxidative stress-related spontaneous PTB and to give a critical approach on future perspectives on this topic as a classical example of translational medicine. Placenta-mediated pregnancy adverse outcome associated with OS leading to iatrogenic PTB (e.g. pre-eclampsia, intrauterine growth restriction, gestational diabetes) will not be discussed.

Erythrocyte and plasma oxidative stress appears to be compensated in patients with sickle cell disease during a period of relative health, despite the presence of known oxidative agents

Sickle cell disease (SCD) is a monogenetic disease that results in the formation of hemoglobin S. Due to more rapid oxidation of hemoglobin S due to intracellular heme and adventitious iron in SCD, it has been thought that an inherent property of SCD red cells would be an imbalance in antioxidant defenses and oxidant production. Less deformable and fragile RBC in SCD results in intravascular hemolysis and release of free hemoglobin (PFHb) in the plasma, which might be expected to produce oxidative stress in the plasma. Thus, we aimed to characterize intracellular and vascular oxidative stress in whole blood and plasma samples from adult SCD patients and controls recruited into a large study of SCD at Children's Hospital of Los Angeles. We evaluated the cellular content of metHb and several components of the antioxidant system in RBC as well as oxidation of GSH and Prx-2 oxidation in RBC after challenge with hydroperoxides. Plasma markers included PFHb, low molecular weight protein bound heme (freed heme), hemopexin, isoprostanes, and protein carbonyls. While GSH was slightly lower in SCD RBC, protein carbonyls, NADH, NAD+ and total NADP+ + NADPH were not different. Furthermore, GSH or Prx-2 oxidation was not different after oxidative challenge in SCD vs. Control. Elevated freed heme and PFHb had a significant negative, non-linear association with hemopexin. There appeared to be a threshold effect for hemopexin (200 μg/ml), under which the freed heme rose acutely. Plasma F2-isoprostanes were not significantly elevated in SCD. Despite significant release of Hb and elevation of freed heme in SCD when hemopexin was apparently saturated, there was no clear indication of uncompensated vascular oxidative stress. This somewhat surprising result, suggests that oxidative stress is well compensated in RBCs and plasma during a period of relative health.

Increased isoprostanoid levels in brain from murine model of Krabbe disease - Relevance of isoprostanes, dihomo-isoprostanes and neuroprostanes to disease severity

Krabbe disease (KD) is a rare and devastating pediatric leukodystrophy caused by mutations in the galactocerebrosidase (GALC) gene. The disease leads to impaired myelin formation and extensive myelin damage in the brain. Oxidative stress is implicated in the pathogenesis of KD but insofar few information is available. The gray and white matter of the brain are rich in docosahexaenoic acid and adrenic acid respectively and under non-enzymatic oxidative stress, release isoprostanoids, i.e. F₄-neuroprostanes (F₄-NeuroPs) and F₂-dihomo-isoprostanes (F₂-dihomo-IsoPs). In this study, the formation of isoprostanoids in brain tissue was investigated in a well-established KD mouse model (twitcher) that recapitulates the human pathology. According to the genotype determinations, three groups of mice were selected: wild-type control mice (n = 13), heterozygotes mice (carriers of GALC mutations, n = 14) and homozygous twitcher mice (n = 13). Measurement of F₂-dihomo-IsoP and F₄-NeuroP levels were performed on whole brain tissue obtained at day 15 and day 35 of the life cycle. Brain isoprostanoid levels were significantly higher in the twitcher mice compared to the heterozygous and wild-type control mice. However, F₂-dihomo-IsoP and F₄-NeuroP levels did not differ in brain of day 15 compared to day 35 of the heterozygote mice. Interestingly, isoprostanoid levels were proportionally enhanced with disease severity (F₂-dihomo-IsoPs, rho = 0.54; F₄-NeuroPs, rho = 0.581; P values ≤ 0.05; n = 13). Our findings are the first to show the key role of polyunsaturated fatty acid oxidative damage to brain grey and white matter in the pathogenesis and progression of KD. This shed new insights on the biochemical indexes of KD progression, and potentially provide information for novel therapeutic targets.

Regional differences of hypothermia on oxidative stress following hypoxia-ischemia: a study of DHA and hypothermia on brain lipid peroxidation in newborn piglets

Background Oxidative stress plays an important part in the pathophysiology of hypoxic-ischemic encephalopathy (HIE) and is reliably measured through prostanoids following lipid peroxidation of polyunsaturated fatty acids (PUFAs). The aim of the study is to measure oxidative stress in the prefrontal cortex, white matter and hippocampus in the brains of hypoxic-ischemic piglets treated with docosahexaenoic acid (DHA) and therapeutic hypothermia (TH) and investigate the additive effects of DHA on hypothermia by factorial design. Methods Fifty-five piglets were randomized as having severe global hypoxia (n=48) or not (sham, n=7). Hypoxic piglets were further randomized: vehicle (VEH), DHA, VEH+hypothermia (HT) or HT+DHA. A total of 5 mg/kg DHA was given intravenously 210 min after the end of hypoxia. Brain tissues were analyzed using liquid chromatography triple quadrupole mass spectrometry technique (LC-MS). A two-way analysis of variance (ANOVA) was performed with DHA and HT as main effects. Results In the white matter, we found main effects of DHA on DH-isoprostanes (P=0.030) and a main effect of HT on F4-neuroprostanes (F4-NeuroPs) (P=0.007), F2-isoprostanes (F2-IsoPs) (P=0.043) and DH-isoprostanes (P=0.023). In the cortex, the ANOVA analysis showed the interactions of main effects between DHA and HT for neurofuranes (NeuroFs) (P=0.092) and DH-isoprostanes (P=0.015) as DHA significantly reduced lipid peroxidation in the absence of HT. DHA compared to VEH significantly reduced NeuroFs (P=0.019) and DH-isoprostanes (P=0.010). No differences were found in the hippocampus. Conclusion After severe hypoxia, HT reduced lipid peroxidation in the white matter but not in the cortical gray matter. HT attenuated the reducing effect of DHA on lipid peroxidation in the cortex. Further studies are needed to determine whether DHA can be an effective add-on therapy for TH.

Non-Enzymatic Synthesis of Bioactive Isoprostanoids in the Diatom Phaeodactylum following Oxidative Stress

The ecological success of diatoms requires a remarkable ability to survive many types of stress, including variations in temperature, light, salinity, and nutrient availability. On exposure to these stresses, diatoms exhibit common responses, including growth arrest, impairment of photosynthesis, production of reactive oxygen species, and accumulation of triacylglycerol (TAG). We studied the production of cyclopentane oxylipins derived from fatty acids in the diatom Phaeodactylum tricornutum in response to oxidative stress. P. tricornutum lacks the enzymatic pathway for producing cyclopentane-oxylipins, such as jasmonate, prostaglandins, or thromboxanes. In cells subjected to increasing doses of hydrogen peroxide (H₂O₂), we detected nonenzymatic production of isoprostanoids, including six phytoprostanes, three F_2t-isoprostanes, two F_3t-isoprostanes, and three F_4t-neuroprostanes, by radical peroxidation of α-linolenic, arachidonic, eicosapentaenoic, and docosahexanoic acids, respectively. H₂O₂ also triggered photosynthesis impairment and TAG accumulation. F_1t-phytoprostanes constitute the major class detected (300 pmol per 1 million cells; intracellular concentration, ∼4 µm). Only two glycerolipids, phosphatidylcholine and diacylglycerylhydroxymethyl-trimethyl-alanine, could provide all substrates for these isoprostanoids. Treatment of P. tricornutum with nine synthetic isoprostanoids produced an effect in the micromolar range, marked by the accumulation of TAG and reduced growth, without affecting photosynthesis. Therefore, the emission of H₂O₂ and free radicals upon exposure to stresses can lead to glycerolipid peroxidation and nonenzymatic synthesis of isoprostanoids, inhibiting growth and contributing to the induction of TAG accumulation via unknown processes. This characterization of nonenzymatic oxylipins in P. tricornutum opens a field of research on the study of processes controlled by isoprostanoid signaling in various physiological and environmental contexts in diatoms.

Gp91phox (NOX2) in Activated Microglia Exacerbates Neuronal Damage Induced by Oxygen Glucose Deprivation and Hyperglycemia in an in Vitro Model

BACKGROUND/AIMS

Peri-operative cerebral ischemia reperfusion injury is one of the most serious peri-operative complications that can be aggravated in patients with diabetes. A previous study showed that microglia NOX2 (a NADPH oxidase enzyme) may play an important role in this process. Here, we investigated whether increased microglial derived gp91phox, also known as NOX2, reduced oxygen glucose deprivation (OGD) after induction of hyperglycemia (HG).

METHODS

A rat neuronal-microglial in vitro co-culture model was used to determine the effects of gp91phox knockdown on OGD after HG using six treatment groups: A rat microglia and neuron co-culture model was established and divided into the following six groups: high glucose + scrambled siRNA transfection (HG, n = 5); HG + gp91phoxsiRNA transfection (HG-gp91siRNA, n = 5); oxygen glucose deprivation + scrambled siRNA transfection (OGD, n = 5); OGD + gp91phoxsiRNA transfection (OGD-gp91siRNA, n = 5); HG + OGD + scrambled siRNA transfection (HG-OGD, n = 5); and HG + OGD + gp91phoxsiRNA transfection (HG-OGD-gp91siRNA, n = 5). The neuronal survival rate was measured by the MTT assay, while western blotting was used to determine gp91phox expression. Microglial derived ROS and neuronal apoptosis rates were analyzed by flow cytometry. Finally, the secretion of cytokines, including IL-6, IL-8, TNF-α, and 8-iso-PGF2α was determined using an ELISA kit.

RESULTS

Neuronal survival rates were significantly decreased by HG and OGD, while knockdown of gp91phox reversed these rates. ROS production and cytokine secretion were also significantly increased by HG and OGD but were significantly inhibited by knockdown of gp91phoxsiRNA.

CONCLUSION

Knockdown of gp91phoxsiRNA significantly reduced oxidative stress and the inflammatory response, and alleviated neuronal damage after HG and OGD treatment in a rat neuronal-microglial co-culture model.

Effects of Cyclic Fatty Acid Monomers from Heated Vegetable Oil on Markers of Inflammation and Oxidative Stress in Male Wistar Rats

This study assesses the effects of cyclic fatty acid monomers (CFAM) from heated vegetable oils on oxidative stress and inflammation. Wistar rats were fed either of these four diets for 28 days: canola oil (CO), canola oil and 0.5% CFAM (CC), soybean oil (SO), and soybean oil and 0.5% CFAM (SC). Markers of oxidative stress and inflammation were determined by micro liquid chromatography tandem mass spectrometry (micro-LC-MS/MS) and enzyme-linked immunosorbent assay (ELISA) kits, respectively. Analysis of variance (ANOVA) for a 2 × 2 factorial design was performed to determine the CFAM and oil effects and interactions between these two factors at P ≤ 0.05. For significant interactions, a post hoc multiple comparison test was performed, i.e., Tukey HSD (honest significant difference) test. CFAM induced higher plasma levels of 15-F_2t-IsoP (CC, 396 ± 43 ng/mL, SC, 465 ± 75 ng/mL vs CO, 261 ± 23 ng/mL and SO, 288 ± 35 ng/mL, P < 0.05). Rats fed the SC diet had higher plasma 2,3-dinor-15-F_2t-IsoP (SC, 145 ± 9 ng/mL vs CC, 84 ± 8 ng/mL, CO, 12 ± 1 ng/mL, and SO, 12 ± 1 ng/mL, P < 0.05), urinary 2,3-dinor-15-F_2t-IsoP (SC, 117 ± 12 ng/mL vs CC, 67 ± 13 ng/mL, CO, 15 ± 2 ng/mL, and SO, 18 ± 4 ng/mL, P < 0.05), and plasma IL-6 (SC, 57 ± 10 pg/mL vs CC, 48 ± 11 pg/mL, CO, 46 ± 9 pg/mL, and SO, 44 ± 4 pg/mL, P < 0.05) than the other three diet groups. These results indicate that CFAM increased the levels of markers of oxidative stress, and those effects are exacerbated by a CFAM-high-linoleic acid diet.

4-hydroxynonenal protein adducts: Key mediator in Rett syndrome oxinflammation

In the last 15 years a strong correlation between oxidative stress (OxS) and Rett syndrome (RTT), a rare neurodevelopmental disorder known to be caused in 95% of the cases, by a mutation in the methyl-CpG-binding protein 2 (MECP2) gene, has been well documented. Here, we revised, summarized and discussed the current knowledge on the role of lipid peroxidation byproducts, with special emphasis on 4-hydroxynonenal (4HNE), in RTT pathophysiology. The posttranslational modifications of proteins via 4HNE, known as 4HNE protein adducts (4NHE-PAs), causing detrimental effects on protein functions, appear to contribute to the clinical severity of the syndrome, since their levels increase significantly during the subsequent 4 clinical stages, reaching the maximum degree at stage 4, represented by a late motor deterioration. In addition, 4HNE-PA are only partially removed due to the compromised functionality of the proteasome activity, contributing therefore to the cellular damage in RTT. All this will lead to a characteristic subclinical inflammation, defined "OxInflammation", derived by a positive feedback loop between OxS byproducts and inflammatory mediators that in a long run further aggravates the clinical features of RTT patients. Therefore, in a pathology completely orphan of any therapy, aiming 4HNE as a therapeutic target could represent a coadjuvant treatment with some beneficial impact in these patients.‬‬‬.

Oxidative stress in newborns by different modes of delivery

OBJECTIVES

The aim of our study is to investigate the impact of the type of delivery - vaginal vs. cesarean section on oxidative damage determined as the lipid peroxidation (15-F2t-isoprostane (15-F2t-IsoP) in the cord blood of newborns and venous blood from mothers in two localities with different levels of air pollution: Ceske Budejovice (CB), a locality with a clean air, and Karvina, a locality with high air pollution.

RESUTLS

In Karvina, the concentration of PM2.5 was higher than in CB in the summer 2013 (mean±SD: 20.41±6.28 vs. 9.45±3.62 µg/m3, p<0.001) and in the winter 2014 (mean±SD: 53.67±19.76 vs. 27.96±12.34 µg/m3, p<0.001). Similarly, the concentration of B[a]P was higher in Karvina than in CB in the summer 2013 (mean±SD: 1.16±0.91 vs. 0.16±0.26 ng/m3, p<0.001) and in the winter 2014 (5.36±3.64 vs. 1.45±1.19 ng/m3, p<0.001). Delivery procedures differed by the type of anesthesia; at the Cesarean section in CB was used general anesthesia in 73.8% vs. 20.8% in Karvina (p<0.001), epidural anesthesia in CB in 26.2% vs. 77.1% in Karvina (p<0.001), at vaginal delivery was local anesthesia used in CB in 58.9% vs. 14.1% in Karvina (p<0.001). In CB was oxidative stress higher after vaginal delivery (101.7±31.0 pg 15-F2t-isoP/ml plasma) vs. Cesarean section (83.9±26.9 pg 15-F2t-isoP/ml plasma, p<0.001), no difference between the type of delivery was observed in Karvina.

CONCLUSION

No difference between the types of delivery was observed in mothers in CB as well as in Karvina. Oxidative stress in newborns in Karvina was significantly affected by the concentrations of PM2.5 and B[a]P in the polluted air.

The impact of silica encapsulated cobalt zinc ferrite nanoparticles on DNA, lipids and proteins of rat bone marrow mesenchymal stem cells

Nanomaterials are currently the subject of intense research due to their wide variety of potential applications in the biomedical, optical and electronic fields. We prepared and tested cobalt zinc ferrite nanoparticles (Co0.5Zn0.5Fe2O4+γ [CZF-NPs]) encapsulated by amorphous silica in order to find a safe contrast agent and magnetic label for tracking transplanted cells within an organism using magnetic resonance imaging (MRI). Rat mesenchymal stem cells (rMSCs) were labeled for 48 h with a low, medium or high dose of CZF-NPs (0.05; 0.11 or 0.55 mM); silica NPs (Si-NPs; 0.11 mM) served as a positive control. The internalization of NPs into cells was verified by transmission electron microscopy. Biological effects were analyzed at the end of exposure and after an additional 72 h of cell growth without NPs. Compared to untreated cells, Annexin V/Propidium Iodide labeling revealed no significant cytotoxicity for any group of treated cells and only a high dose of CZF-NPs slowed down cell proliferation and induced DNA damage, manifested as a significant increase of DNA-strand breaks and oxidized DNA bases. This was accompanied by high concentrations of 15-F2t-isoprostane and carbonyl groups, demonstrating oxidative injury to lipids and proteins, respectively. No harmful effects were detected in cells exposed to the low dose of CZF-NPs. Nevertheless, the labeled cells still exhibited an adequate relaxation rate for MRI in repeated experiments and ICP-MS confirmed sufficient magnetic label concentrations inside the cells. The results suggest that the silica-coated CZF-NPs, when applied at a non-toxic dose, represent a promising contrast agent for cell labeling.

Sustained Isoprostane E2 Elevation, Inflammation and Fibrosis after Acute Ischaemia-Reperfusion Injury Are Reduced by Pregnane X Receptor Activation

Liver grafts donated after cardiac death are increasingly used to expand the donor pool but are prone to ischaemic-type biliary lesions. The anti-inflammatory effects of the activated pregnane X receptor have previously been shown to be beneficial in a number of inflammatory liver conditions. However, its role in reducing peri-portal inflammation and fibrosis following ischaemia-reperfusion injury has not been investigated. Hepatic injury and its response to pregnane X receptor activation was examined after partial hepatic ischaemia-reperfusion injury induced by surgically clamping the left and middle lobar blood vessels in rats. Molecular and pathological changes in the liver were examined over the following 28 days. Ischaemia-reperfusion injury resulted in transient cholestasis associated with microvillar changes in biliary epithelial cell membranes and hepatocellular injury which resolved within days after reperfusion. However, in contrast to chemically-induced acute liver injuries, this was followed by sustained elevation in isoprostane E2, peri-portal inflammation and fibrosis that remained unresolved in the ischaemic reperfused lobe for at least 28 days after clamping. Administration of pregnenolone-16α-carbonitrile—a rodent-specific pregnane X receptor activator—resulted in significant reductions in cholestasis, hepatic injury, ischaemic lobe isoprostane E2 levels, peri-portal inflammation and fibrosis. Hepatic ischaemia-reperfusion injury therefore results in inflammatory and fibrotic changes that persist well beyond the initial ischaemic insult. Drug-mediated activation of the pregnane X receptor reduced these adverse changes in rats, suggesting that the pregnane X receptor is a viable drug target to reduce ischaemic-type biliary lesions in recipients of liver transplants donated after cardiac death.

Isoprostanes and neuroprostanes as biomarkers of oxidative stress in neurodegenerative diseases

Accumulating data shows that oxidative stress plays a crucial role in neurodegenerative disorders. The literature data indicate that in vivo or postmortem cerebrospinal fluid and brain tissue levels of F2-isoprostanes (F2-IsoPs) especially F4-neuroprotanes (F4-NPs) are significantly increased in some neurodegenerative diseases: multiple sclerosis, Alzheimer's disease, Huntington's disease, and Creutzfeldt-Jakob disease. Central nervous system is the most metabolically active organ of the body characterized by high requirement for oxygen and relatively low antioxidative activity, what makes neurons and glia highly susceptible to destruction by reactive oxygen/nitrogen species and neurodegeneration. The discovery of F2-IsoPs and F4-NPs as markers of lipid peroxidation caused by the free radicals has opened up new areas of investigation regarding the role of oxidative stress in the pathogenesis of human neurodegenerative diseases. This review focuses on the relationship between F2-IsoPs and F4-NPs as biomarkers of oxidative stress and neurodegenerative diseases. We summarize the knowledge of these novel biomarkers of oxidative stress and the advantages of monitoring their formation to better define the involvement of oxidative stress in neurological diseases.

Is there a clinical role for oxidative stress biomarkers in atherosclerotic diseases?

Growing evidences suggest that reactive oxidant species (ROS) are involved in the pathogenesis and progression of the atherosclerotic diseases. Markers assessing the oxidation of LDL and formation of eicosanoids, such as isoprostanes, were among the first that were analyzed. More recently, new biomarkers, such as endogenous secretory receptor for AGEs have been suggested to play an oxidative role in specific atherosclerotic settings, such as diabetes. Unfortunately, clinical trials included cross-sectional as well as retrospective and prospective studies which provide inconclusive results. Thus, clear evidence that oxidative biomarkers can improve risk stratification in addition to the common used atherosclerotic risk factors is still lacking. The analysis of oxidative stress focused on enzymatic systems generating ROS. The most studied enzymes were NADPH oxidase and myeloperoxidase (MPO). Experimental and clinical studies suggest that both enzymes may be implicated in promoting atherosclerotic disease. Novel laboratory methodologies have been, therefore, developed to study NADPH oxidase and MPO in patients with stable atherosclerosis as well in patients with acute coronary syndrome and cerebrovascular accident. This review will report on the more relevant studies in which the clinical application of the oxidative biomarkers was evaluated.

[Oxidative stress and Rett syndrome]

The oxidative stress (OS) hypothesis is able to explain several features of Rett syndrome (RTT), a pervasive development disorder almost exclusively affecting females mainly caused by a mutation in the X-linked methyl-CpG binding protein 2 (MeCP2) gene. In particular, the generation of an OS imbalance is related to MeCP2 gene mutation type, as well as natural history, clinical heterogeneity of the disease, and is compatible with the potential reversibility of the disease observed in the RTT animal models. In addition, our findings indicate the importance of blood as a suitable biological fluid for detecting markers of central nervous system oxidative damage in RTT and underline the key role of interaction between organic chemists, OS biochemists, and clinicians in revealing potential new markers of the disease and identifying potential new targets and interventional strategies aimed at improving the quality of life of these patients, affected by a so far incurable disease. Further efforts in the near future are needed in order to dissect the "black box" of the molecular events likely linking the MeCP2 gene mutation to OS derangement and subsequent disease expression.

Gene expression profiles of peripheral blood mononuclear cells reveal transcriptional signatures as novel biomarkers of cardiac remodeling in rats with aldosteronism and hypertensive heart disease

OBJECTIVES

In searching for a noninvasive surrogate tissue mimicking the pro-oxidant/proinflammatory hypertensive heart disease (HHD) phenotype, we turned to peripheral blood mononuclear cells (PBMCs). We tested whether iterations in [Ca2+]i, [Zn2+]i, and oxidative stress in cardiomyocytes and PBMCs would complement each other, eliciting similar shifts in gene expression profiles in these tissues demonstrable during the preclinical (week 1) and pathological (week 4) stages of aldosterone/salt treatment (ALDOST).

BACKGROUND

Inappropriate neurohormonal activation contributes to pathological remodeling of myocardium in HHD associated with aldosteronism. In rats receiving long-term ALDOST, evidence of reparative fibrosis replacing necrotic cardiomyocytes and coronary vasculopathy appears at week 4 associated with the induction of oxidative stress by mitochondria that overwhelms endogenous, largely Zn2+-based, antioxidant defenses. Biomarker-guided prediction of risk before the appearance of cardiac pathology would prove invaluable.

METHODS

In PBMCs and cardiomyocytes, quantitation of cytoplasmic free Ca2+ and Zn2+, H2O2, and 8-iosprostane levels and isolation of ribonucleic acid (RNA) and gene expression together with statistical and clustering analyses and confirmation of genes by in situ hybridization and reverse-transcription polymerase chain reaction were performed.

RESULTS

Compared with controls, at weeks 1 and 4 of ALDOST, we found comparable increments in [Ca2+]i, [Zn2+]i, and 8-isoprotane coupled with increased H2O2 production in cardiac mitochondria and PBMCs, together with the common networks of expression profiles dominated by genes involved in oxidative stress, inflammation, and repair. These included 3 central Ingenuity pathway-linked genes: p38 mitogen-activated protein kinase, a stress-responsive protein; nuclear factor-κB, a redox-sensitive transcription factor and a proinflammatory cascade that it regulates; and transforming growth factor-β1, a fibrogenic cytokine involved in tissue repair.

CONCLUSIONS

Significant overlapping demonstrated in the molecular mimicry of PBMCs and cardiomyocytes during preclinical and pathological stages of ALDOST implies that transcriptional signatures of PBMCs may serve as early noninvasive and novel sentinels predictive of impending pathological remodeling in HHD.

Signaling pathways involved in isoprostane-mediated fibrogenic effects in rat hepatic stellate cells

Despite evidence supporting a potential role for F2-isoprostanes (F2-IsoP's) in liver fibrosis, their signaling mechanisms are poorly understood. We have previously provided evidence that F2-IsoP's stimulate hepatic stellate cell (HSC) proliferation and collagen hyperproduction by activation of a modified form of isoprostane receptor homologous to the classic thromboxane receptor (TP). In this paper, we examined which signal transduction pathways are set into motion by F2-IsoP's to exert their fibrogenic effects. HSCs were isolated from rat liver, cultured to their activated myofibroblast-like phenotype, and then treated with the isoprostane 15-F2t-isoprostane (15-F2t-IsoP). Inositol trisphosphate (IP3) and adenosine 3',5'-cyclic monophosphate (cAMP) levels were determined using commercial kits. Mitogen-activated protein kinase (MAPK) and cyclin D1 expression was assessed by Western blotting. Cell proliferation and collagen synthesis were determined by measuring [(3)H]thymidine and [(3)H]proline incorporation, respectively. 15-F2t-IsoP elicited an activation of extracellular-signal-regulated kinase (ERK), p38 MAPK, and c-Jun NH2-terminal kinase (JNK), which are known to be also regulated by G-protein-coupled receptors. Preincubation with specific ERK (PD98059), p38 (SB203580), or JNK (SP600125) inhibitors prevented 15-F2t-IsoP-induced cell proliferation and collagen synthesis. 15-F2t-IsoP decreased cAMP levels within 30 min, suggesting binding to the TPβ isoform and activation of Giα protein. Also, 15-F2t-IsoP increased IP3 levels within a few minutes, suggesting that the Gq protein pathway is also involved. In conclusion, the fibrogenic effects of F2-IsoP's in HSCs are mediated by downstream activation of MAPKs, through TP binding that couples via both Gqα and Giα proteins. Targeting TP receptor, or its downstream pathways, may contribute to preventing oxidative damage in liver fibrosis.

Identification of lipid derivatives in Hep G2 cells

Metabolism of polyunsaturated fatty acids results in biosynthesis of mediators with different physiological effects. These metabolites include prostaglandins, prostacyclins, isoprostanes and others that are important signalling molecules and regulate a variety of physiological and pathophysiological processes including inflammation. Prostaglandins and isoprostanes are produced by either non-enzymatic lipid peroxidation or by enzyme-induced peroxidation (cyclooxygenases and lipoxygenases). They are used as biomarkers of oxidative stress. The aim of our study was to assess the effect of eicosapentaenoic acid (EPA) supplementation with added benzo(a)pyrene (BaP) on HepG2 cells by using a UHPLC/MS-TOF method. This rapid and simple method was developed for the identification, separation and quantification of 8-iPGF3α, PGF3α, 8-isoPGF2α and 5-iPF2α in cultured cells. The UHPLC/MS-TOF method was validated. The calculated limit of detection was in the range of 0.16-0.50 ng/mL, precision (% RSD): 1.2-2.1% and recoveries better than 88%. This method empowered qualitative and quantitative analysis of the selected individual prostaglandins derived from arachidonic acid and eicosapentaenoic acid from cell extracts.

Obese rats exhibit high levels of fat necrosis and isoprostanes in taurocholate-induced acute pancreatitis

BACKGROUND

Obesity is a prognostic factor for severity in acute pancreatitis in humans. Our aim was to assess the role of oxidative stress and abdominal fat in the increased severity of acute pancreatitis in obese rats.

METHODOLOGY

Taurocholate-induced acute pancreatitis was performed in lean and obese Zucker rats. Levels of reduced glutathione, oxidized glutathione, L-cysteine, cystine, and S-adenosylmethionine were measured in pancreas as well as the activities of serine/threonine protein phosphatases PP1 and PP2A and tyrosin phosphatases. Isoprostane, malondialdehyde, triglyceride, and free fatty acid levels and lipase activity were measured in plasma and ascites. Lipase activity was measured in white adipose tissue with and without necrosis and confirmed by western blotting.

FINDINGS

Under basal conditions obese rats exhibited lower reduced glutathione levels in pancreas and higher triglyceride and free fatty acid levels in plasma than lean rats. S-adenosyl methionine levels were markedly increased in pancreas of obese rats. Acute pancreatitis in obese rats led to glutathione oxidation and lower reduced glutathione levels in pancreas together with decreased activities of redox-sensitive phosphatases PP1, and PP2A. S-adenosyl methionine levels decreased but cystine levels increased markedly in pancreas upon pancreatitis. Acute pancreatitis triggered an increase in isoprostane levels in plasma and ascites in obese rats. Free fatty acid levels were extremely high in pancreatitis-associated ascitic fluid from obese rats and lipase was bound with great affinity to white adipose tissue, especially to areas of necrosis.

CONCLUSIONS

Our results show that oxidative stress occurs locally and systemically in obese rats with pancreatitis favouring inactivation of protein phosphatases in pancreas, which would promote up-regulation of pro-inflammatory cytokines, and the increase of isoprostanes which might cause powerful pulmonary and renal vasoconstriction. Future studies are needed to confirm the translational relevance of the present findings obtained in a rat model of taurocholate-induced pancreatic damage and necrosis.

Allopurinol attenuates left ventricular dysfunction in rats with early stages of streptozotocin-induced diabetes

BACKGROUND

Xanthine oxidase-derived superoxide production and oxidative stress contribute to the development of diabetic complications including diabetic cardiomyopathy. We hypothesized that xanthine oxidase-inhibitor allopurinol (ALP) may decrease hyperglycemia-induced oxidative stress, ameliorate cardiomyocyte hypertrophy and fibrosis, and attenuate the development of left ventricle (LV) diastolic dysfunction in rats with streptozotocin (STZ)-induced diabetes.

METHODS

Control Sprague Dawley (C) or streptozotocin-induced diabetic (D) rats were either untreated or treated with allopurinol (100 mg/kg/day) for 4 weeks starting at 1 week after streptozotocin injection. Free 15-F2t-isoprostane, a specific indicator of oxidative stress was measured by enzymatic immunoassay. The cardiomyocyte cross-sectional area was assessed by hematoxylin and eosin-stained paraffin-embedded sections of LVs. Myocardial collagens I and III were assessed by immunol histochemistry and Western blotting. Echocardiography was performed to characterize cardiac structure and function.

RESULTS

In diabetic rats, both plasma and cardiac tissue levels of free 15-F2t-isoprostane were increased (p < 0.05 vs. control), accompanied with significant increase (p < 0.05 vs. control) in cross-section area and myocardial collagen deposition of LV cardiomyocyte. Echocardiography in diabetic rats showed that LV weight/body weight ratio was significantly higher than in control rats, whereas the levels of LV end-diastolic volume and stroke volume were decreased (all p < 0.05 diabetic vs. control). All these changes were either attenuated or prevented by allopurinol. In addition, LV ejection fraction in diabetic rats treated with allopurinol was higher than that in untreated diabetic rats (p < 0.05).

CONCLUSION

Allopurinol can attenuate hyperglycemia-induced oxidative stress, ameliorate cardiomyocyte hypertrophy and fibrosis and subsequently prevent left ventricular dysfunction in early diabetes.

Influence of cigarette smoking on synthesis of eicosanoids, isoprostanes and lipoxygenase metabolites in apical periodontitis

Arachidonic acid (AA) is metabolized to eicosanoids and isoprostanes (IPs) via different pathways. The presence of granuloma in apical periodontitis (AP) is linked with inflammation and the synthesis of metabolites of AA.

OBJECTIVE

We investigated the conversion rate of (14)C labelled arachidonic acid ((14)C-AA), the lipoxygenases (LOX) products and the endogenous synthesis of eicosanoids and IPs in extracted granuloma. Furthermore, we assessed if there are markers for bone destruction and the influence of cigarette smoking.

PATIENTS AND METHODS

In 46 patients with symptoms and corresponding radiological signs of AP, teeth were extracted including the periapical granuloma. The endogenous synthesis of eicosanoids and IPs, the conversion rate of (14)C-AA and LOX products in extracted granuloma were analyzed.

RESULTS

We found that smoking increases significantly the synthesis of IPs and LOX-metabolites in granuloma. Furthermore, smoking may have contributed to significant differences in qualitative and quantitative profile of eicosanoids, IPs and the conversion rate of (14)C-AA independent of the size of the granuloma.

CONCLUSIONS

Our data demonstrate that in smokers with granuloma due to AP products of lipid peroxidation as 8-iso-PGF(2α) and products of the LOX-pathway are increased at the expense of cyclooxygenase products. The size of granuloma did not influence the amount of synthesized eicosanoids, IPs or LOX-metabolites out of (14)C-AA whereas cigarette smoking was a significantly influencing and modifiable risk factor.

Platelet isoprostane overproduction in diabetic patients treated with aspirin

Aspirin modestly influences cardiovascular events in patients with type 2 diabetes mellitus (T2DM), but the reason is unclear. The aim of the study was to determine whether in T2DM patients aspirin enhances platelet isoprostanes, which are eicosanoids with proaggregating properties derived from arachidonic acid oxidation by platelet NOX2, the catalytic subunit of reduced NAD phosphate oxidase. A cross-sectional study was performed comparing T2DM patients, treated (n = 50) or not treated (n = 50) with 100 mg/day aspirin, with 100 nondiabetic patients, matched for age, sex, atherosclerosis risk factors, and aspirin treatment. A short-term (7 days) treatment with 100 mg/day aspirin also was performed in 36 aspirin-free diabetic and nondiabetic patients. Higher platelet recruitment, platelet isoprostane, and NOX2 activation was found in diabetic versus nondiabetic patients and in aspirin-treated diabetic patients versus nontreated patients (P < 0.001). Platelet thromboxane (Tx) A(2) (P < 0.001) was inhibited in all aspirin-treated patients. In the interventional study, aspirin similarly inhibited platelet TxA(2) in diabetic and nondiabetic patients (P < 0.001). Platelet recruitment, isoprostane levels, and NOX2 activation showed a parallel increase in diabetic patients (P < 0.001) and no changes in nondiabetic patients. These findings suggest that in aspirin-treated diabetic patients, oxidative stress-mediated platelet isoprostane overproduction is associated with enhanced platelet recruitment, an effect that mitigates aspirin-mediated TxA(2) inhibition.

Longitudinal study of vitamins A, E and lipid oxidative damage in human milk throughout lactation

BACKGROUND

Little is known about the intensity of oxidative damage in human milk resulting from maternal oxidative stress. The aim of our study was to explore the changes in Total Antioxidant Status (TAS) and concentrations of antioxidative vitamins and isoprostanes (markers of oxidative stress) in human colostrum and mature milk.

METHODS

The study included 49 postpartum women with normal, spontaneous full term delivery. The exclusion criteria included active and passive smoking, acute and chronic disorders, and pharmacotherapy other than vitamin supplementation. Colostrum samples were collected on the 3rd day after delivery and breast milk samples between the 30th and the 32nd day after delivery. TAS of colostrum/breast milk was determined by Rice-Evans and Miller method. The amount of vitamins A and E was measured by HPLC. Isoprostane concentrations in colostrum/mature milk and urine were determined immunoenzymatically.

RESULTS

No significant differences were observed in maternal dietary intakes of vitamins A and E determined prior to the colostrum and mature milk sampling. The TAS of mature milk was significantly higher compared to colostrum (P=0.002), while vitamin A and E concentrations were significantly lower (P=0.003 and P=0.001). Although the isoprostane concentration of mature milk was significantly higher than the colostrum concentration, this difference was not significant (P=0.129).

CONCLUSION

Human milk is a source of antioxidative vitamins and their concentrations decrease throughout the lactation, while their total antioxidative properties increase. The phase of lactation does not affect the degree of human milk's lipid oxidative damage.

Role of polyunsaturated fatty acids and lipid peroxidation on colorectal cancer risk and treatments

PURPOSE OF REVIEW

The review aims at elucidating the role of lipid peroxidation of polyunsaturated fatty acids (PUFAs) in colorectal cancer (CRC) risk and treatment.

RECENT FINDINGS

CRC is one of the most overriding threats to public health. Despite a broad range of treatments, up to 50% of patients will inevitably develop incurable metastatic disease. Peroxidation of PUFAs contributes to augmentation of oxidative stress and causes in consequence inflammation, which is one of the possible carcinogenic factors of CRC. End products of PUFAs might be used as biomarkers for CRC detection and surveillance for treatment. They also have cytotoxic effect in CRC cells. Experimental results suggest that ω-3 PUFAs could increase the efficacy of radiotherapy and chemotherapy of CRC.

SUMMARY

Lipid peroxidation, one factor of oxidative stress, might play a paramount role not only in carcinogenesis but also in potential therapeutic strategy on CRC. End products of lipid peroxidation, such as malondialdehyde, 4-hydroxy-2-nonenal, and isoprostanes, could be used as biomarkers for cancer detection, surveillance of treatment outcome and prognostic index for CRC patients. Furthermore, malondialdehyde and 4-hydroxy-2-nonenal have cytotoxic effect not only in normal cells but also in CRC cancer cells, which implies the potential role of PUFAs in CRC treatment.

Lipid peroxidation and neurodegenerative disease

Lipid peroxidation is a complex process involving the interaction of oxygen-derived free radicals with polyunsaturated fatty acids, resulting in a variety of highly reactive electrophilic aldehydes. Since 1975, lipid peroxidation has been extensively studied in a variety of organisms. As neurodegenerative diseases became better understood, research establishing a link between this form of oxidative damage, neurodegeneration, and disease has provided a wealth of knowledge to the scientific community. With the advent of proteomics in 1995, the identification of biomarkers for neurodegenerative disorders became of paramount importance to better understand disease pathogenesis and develop potential therapeutic strategies. This review focuses on the relationship between lipid peroxidation and neurodegenerative diseases. It also demonstrates how findings in current research support the common themes of altered energy metabolism and mitochondrial dysfunction in neurodegenerative disorders.

N-acetylcysteine and allopurinol synergistically enhance cardiac adiponectin content and reduce myocardial reperfusion injury in diabetic rats

Background

Hyperglycemia-induced oxidative stress plays a central role in the development of diabetic myocardial complications. Adiponectin (APN), an adipokine with anti-diabetic and anti-ischemic effects, is decreased in diabetes. It is unknown whether or not antioxidant treatment with N-acetylcysteine (NAC) and/or allopurinol (ALP) can attenuate APN deficiency and myocardial ischemia reperfusion (MI/R) injury in the early stage of diabetes.

Methodology/Principal Findings

Control or streptozotocin (STZ)-induced diabetic rats were either untreated (C, D) or treated with NAC (1.5 g/kg/day) or ALP (100 mg/kg/day) or their combination for four weeks starting one week after STZ injection. Plasma and cardiac biochemical parameters were measured after the completion of treatment, and the rats were subjected to MI/R by occluding the left anterior descending artery for 30 min followed by 2 h reperfusion. Plasma and cardiac APN levels were decreased in diabetic rats accompanied by decreased cardiac APN receptor 2 (AdipoR2), reduced phosphorylation of Akt, signal transducer and activator of transcription 3 (STAT3) and endothelial nitric oxide synthase (eNOS) but increased IL-6 and TNF-α (all P<0.05 vs. C). NAC but not ALP increased cardiac APN concentrations and AdipoR2 expression in diabetic rats. ALP enhanced the effects of NAC in restoring cardiac AdipoR2 and phosphorylation of Akt, STAT3 and eNOS in diabetic rats. Further, NAC and ALP, respectively, decreased postischemic myocardial infarct size and creatinine kinase-MB (CK-MB) release in diabetic rats, while their combination conferred synergistic protective effects. In addition, exposure of cultured rat cardiomyocytes to high glucose resulted in significant reduction of cardiomyocyte APN concentration and AdipoR2 protein expression. APN supplementation restored high glucose induced AdipoR2 reduction in cardiomyocytes.

Conclusions/Significance

NAC and ALP synergistically restore myocardial APN and AdipoR2 mediated eNOS activation. This may represent the mechanism through which NAC and ALP combination greatly reduces MI/R injury in early diabetic rats.

Genetic and environmental influence on diabetic rat embryopathy

We assessed genetic and environmental influence on fetal outcome in diabetic rat pregnancy. Crossing normal (N) and manifestly diabetic (MD) Wistar Furth (W) and Sprague-Dawley (L) females with W or L males yielded four different fetal genotypes (WW, LL, WL, and LW) in N or MD rat pregnancies for studies. We also evaluated fetal outcome in litters with enhanced or diminished severity of maternal MD state, denoted MD(+)WL and MD(-)LW. The MDWW litters had less malformations and resorptions (0 and 19%) than the MDLL litters (17 and 30%). The MDWL litters (0 and 8%) were less maldeveloped than the MDLW litters (9 and 22%), whereas the MD(+)WL (3 and 23%) and MD(-)LW (1 and 17%) litters showed increased and decreased dysmorphogenesis (compared with MDWL and MDLW litters). The pregnant MDW rats had lower serum levels of glucose, fructosamine, and branched-chain amino acids than the pregnant MDL rats, whereas the pregnant MD(+)W and MD(-)L rats had levels comparable with those of the MDL and MDW rats, respectively. The 8-iso-PGF2α levels of the malformed MDLW offspring were increased compared with the nonmalformed MDLW offspring. Diabetes decreased fetal heart Ret and increased Bmp-4 gene expression in the MDLW offspring and caused decreased GDNF and Shh expression in the malformed fetal mandible of the MDLW offspring. We conclude that the fetal genome controls the embryonic dysmorphogenesis in diabetic pregnancy by instigating a threshold level for the teratological insult and that the maternal genome controls the teratogenic insult by (dys)regulating the maternal metabolism.

In vitro testing for anti-inflammatory properties of compounds employing peripheral blood mononuclear cells freshly isolated from healthy donors

INTRODUCTION

Inflammation is crucially involved in a variety of diseases like autoimmune syndromes, cardiovascular and neurodegenerative disorders, cancer, sepsis and allograft rejection.

METHODS

Freshly isolated human peripheral blood mononuclear cells (PBMCs) are used as a screening assay for anti-inflammatory properties of compounds. Determinations of neopterin production by ELISA and of tryptophan degradation by HPLC are used as read-outs. Results are compared with further markers of immune response and oxidative stress.

RESULTS

Phytohaemagglutinin induced significant tryptophan degradation and neopterin formation in PBMC, which correlated with IFN-γ, TNF-α, soluble cytokine receptors and isoprostane-8. Addition of vitamin C and E suppressed the responses dose-dependently.

DISCUSSION

The determination of tryptophan degradation and neopterin production in PBMC reflects various pro- and anti-inflammatory cascades that are of relevance also in patients. It constitutes a robust and reliable approach to screen anti-inflammatory or immunosuppressive drugs and may improve throughput, speed and cost-effectiveness in drug discovery.

Reactive gamma-ketoaldehydes formed via the isoprostane pathway disrupt mitochondrial respiration and calcium homeostasis

Isoketals (IsoKs) are gamma-ketoaldehydes formed via the isoprostane pathway of arachidonic acid peroxidation and are among the most reactive by-products of lipid peroxidation. IsoKs selectively adduct to protein lysine residues and are highly cytotoxic, but the targets and molecular events involved in IsoK-induced cell death are poorly defined. Our previous work established that physiologically relevant aldehydes induce mitochondrial dysfunction (Kristal et al., J. Biol. Chem.271:6033-6038; 1996). We therefore examined whether IsoKs induced mitochondrial dysfunction. Incubation of mitochondria with synthetic IsoKs in the presence or absence of Ca(2+) was associated with alterations in mitochondrial respiration, membrane potential (DeltaPsi), and pyridine nucleotide redox state. IsoKs dose dependently (0.5-4microM) accelerated liver mitochondria swelling induced by low concentrations of Ca(2+) and Zn(2+) or by the prooxidant tert-butylhydroperoxide, and release of cytochrome c, with similar observations in heart/brain mitochondria. The mitochondrial permeability transition (mPT) inhibitor cyclosporine A delayed IsoK-induced mitochondria dysfunction. The actions of IsoKs are consistent with interactions with cytochrome c, a protein rich in lysine residues. Direct reaction of IsoKs with select lysines in cytochrome c was demonstrated using high-resolution mass spectrometry. Overall, these results suggest that IsoKs may, in part, mediate their cytotoxic effects through induction of the mPT and subsequent activation of downstream cell death cascades.

Mitochondrial fragmentation and superoxide anion production in coronary endothelial cells from a mouse model of type 1 diabetes

AIMS/HYPOTHESIS

Mitochondria frequently change their shapes by fusion and fission and these morphological dynamics play important roles in mitochondrial function and development as well as programmed cell death. The goal of this study is to investigate whether: (1) mitochondria in mouse coronary endothelial cells (MCECs) isolated from diabetic mice exhibit increased fragmentation; and (2) chronic treatment with a superoxide anion (O(2)(-)) scavenger has a beneficial effect on mitochondrial fragmentation in MCECs.

METHODS

MCECs were freshly isolated and lysed for protein measurement, or cultured to determine mitochondrial morphology and O(2)(-) production. For the ex vivo hyperglycaemia experiments, human coronary endothelial cells were used.

RESULTS

Elongated mitochondrial tubules were observed in MCECs isolated from control mice, whereas mitochondria in MCECs from diabetic mice exhibited augmented fragmentation. The level of optic atrophy 1 (OPA1) protein, which leads to mitochondrial fusion, was significantly decreased, while dynamin-related protein 1 (DRP1), which leads to mitochondrial fission, was significantly increased in MCECs from diabetic mice. Diabetic MCECs exhibited significantly higher O(2)(-) concentrations in cytosol and mitochondria than control MCECs. Administration of the O(2)(-) scavenger TEMPOL to diabetic mice for 4 weeks led to a significant decrease in mitochondrial fragmentation without altering the levels of OPA1 and DRP1 proteins in MCECs. High-glucose treatment for 24 h significantly induced mitochondrial fragmentation, which was restored by TEMPOL treatment. In addition, excess O(2)(-) production, either in cytosol or in mitochondria, significantly increased mitochondrial fragmentation.

CONCLUSIONS/INTERPRETATION

These data suggest that lowering the O(2)(-) concentration can restore the morphological change in mitochondria and may help improve mitochondrial function in diabetic MCECs.

Equivalent lipid oxidation profiles in advanced atherosclerotic lesions of carotid endarterectomy plaques obtained from symptomatic type 2 diabetic and nondiabetic subjects

Type 2 diabetes (T2D) increases the risk for cardiovascular disease and is thought to be associated with increased oxidative stress, a contributor to atherogenesis. Surprisingly, however, there is little direct evidence that T2D-associated oxidative stress results in increased lipid oxidation and/or decreased antioxidant capacity in human atherosclerotic lesions. The aim of this study was to measure vascular lipid oxidation and antioxidants in T2D. The arterial content of oxidized lipid and antioxidants in carotid endarterectomy specimens obtained from diabetic and normoglycemic patients was determined using high-performance liquid chromatography (HPLC), stable isotope dilution gas chromatography-mass spectrometry (GC/MS), and gas-liquid chromatography techniques. The concentrations of hydroxyoctadecanoic acid, F(2)-isoprostanes, and 7-ketocholesterol, as well as alpha-tocopherol, ascorbate, and urate were not different in the two patient groups, whether expressed per unit protein or as a ratio per parent compound. Unexpectedly, a significant decrease in the level of arterial lipid hydroperoxide was found in diabetic patients. Our results do not support the notion that advanced atherosclerotic lesions from T2D patients contain more oxidized lipids than corresponding lesions from nondiabetic subjects.

Fatty acid oxidation and isoprostanes: oxidative strain and oxidative stress

Oxidative stress is implicated as one of the key causes underlying many diseases. Free radicals are important constituents of basal physiology. Assessment of free radicals or the end products of their action has proved to be difficult. Consequently, authentication of the contribution of free radicals to physiology and pathology has usually been equivocal. Isoprostanes are biosynthesized in vivo, predominantly through free radical attack on arachidonic acid and are now regarded as robust biomarkers of oxidative stress in vivo. Isoprostanes are associated with many human diseases, and their concentration is altered over the course of normal human pregnancy, but their (patho)physiological roles have not yet been clearly defined. Measurement of F(2)-isoprostanes in body fluids could offer a unique analytical opportunity to study the role of free radicals in physiology and pathophysiology in order to comprehend both oxidative strain and oxidative stress.

Isoprostane nomenclature: inherent problems may cause setbacks for the development of the isoprostanoid field

Do we have to bother about the isoprostane nomenclature? The widely accepted IUPAC isoprostane nomenclature provides an unambiguous and systematic terminology to name all theoretical possible isoprostanes. However, the currently accepted nomenclature system provides an unnatural framework which is not well suited to address certain biologically relevant questions. Artificial categorization of isoprostanoids into prostanoid families disrupts prostaglandin-ring core structures needed to describe biogenetic precursor-product relationships. In addition, the IUPAC system defines isoprostanoid families which comprise chemically heterogeneous isoprostanoids which largely differ in their physicochemical properties from those of the corresponding prostaglandins. As a result of this, alternative nomenclature systems such as the phytoprostane nomenclature system overcoming some inherent problems of the IUPAC nomenclature are still in use. However, different naming of isoprostanoids especially the classification of prostanoid family names has created considerable confusion. Therefore, a cautionary note on the current use of different nomenclature systems is necessary.

The neurobiology of isoprostanes and Alzheimer's disease

In its sporadic form Alzheimer's disease (AD) results from a combination of genetic and environmental risk factors with abnormal oxidative reactions, which result in free radical mediated injury of the brain. Isoprostanes are oxidized lipids formed by a free radical mediated mechanism, which in recent years have emerged as a reliable and sensitive marker of lipid peroxidation and oxidative stress. Consistent data show that they are increased in the brain of human AD as well as AD animal models. Besides their role as biomarkers, isoprostanes possess important biological effects, functioning as mediators of the cellular response to oxidative stress within the CNS. Recent evidence indicates that these lipid oxidation products, by activating the thromboxane receptor system, mediate the pro-amyloidotic neuronal response to oxidative stress in an experimental model of AD. This novel observation has important clinical implication, since pharmacologic modulation of the TP receptor system by selective antagonists, some of which are already available, could represent a novel therapeutic opportunity for AD as disease-modifying agents.

Addition of n-3 fatty acids to a 4-hour lipid infusion does not affect insulin sensitivity, insulin secretion, or markers of oxidative stress in subjects with type 2 diabetes mellitus

Fatty acids (FA) can impair glucose metabolism to a varying degree depending on time of exposure and also of type of FA. Here we tested for acute effects of marine n-3 FA on insulin sensitivity, insulin secretion, energy metabolism, and oxidative stress. This was a randomized, double-blind, crossover study in 11 subjects with type 2 diabetes mellitus. A 4-hour lipid infusion (Intralipid [Fresenius Kabi, Halden, Norway], total of 384 mL) was compared with a similar lipid infusion partly replaced by Omegaven (Fresenius Kabi) that contributed a median of 0.1 g fish oil per kilogram body weight, amounting to 0.04 g/kg of marine n-3 FA. Insulin sensitivity was assessed by isoglycemic hyperinsulinemic clamps; insulin secretion (measured after the clamps), by C-peptide glucagon tests; and energy metabolism, by indirect calorimetry. Infusion of Omegaven increased the proportion of n-3 FA in plasma nonesterified fatty acids (NEFA) compared with Intralipid alone (20:5n-3: median, 1.5% [interquartile range, 0.6%] vs -0.2% [0.2%], P = .001; 22:6n-3: 0.8% [0.4%] vs -0.7% [0.2%], P = .001). However, glucose utilization was not affected; neither was insulin secretion or total energy production (P = .966, .210, and .423, respectively, for the differences between the lipid clamps). Omegaven tended to lower oxidation of fat (P = .062) compared with Intralipid only, correlating with the rise in individual n-3 NEFA (r = 0.627, P = .039). The effects of clamping on phospholipid FA composition, leptin, adiponectin, or F(2)-isoprostane concentrations were not affected by Omegaven. Enrichment of NEFA with n-3 FA during a 4-hour infusion of Intralipid failed to affect insulin sensitivity, insulin secretion, or markers of oxidative stress in subjects with type 2 diabetes mellitus.

Increased isoprostane levels in oleic acid-induced lung injury

The present study was performed to examine a role of oxidative stress in oleic acid-induced lung injury model. Fifteen anesthetized sheep were ventilated and instrumented with a lung lymph fistula and vascular catheters for blood gas analysis and measurement of isoprostanes (8-epi prostaglandin F2alpha). Following stable baseline measurements, oleic acid (0.08 ml/kg) was administered and observed 4 h. Isoprostane was measured by gas chromatography mass spectrometry with the isotope dilution method. Isoprostane levels in plasma and lung lymph were significantly increased 2 h after oleic acid administration and then decreased at 4 h. The percent increases in isoprostane levels in plasma and lung lymph at 2 h were significantly correlated with deteriorated oxygenation at the same time point, respectively. These findings suggest that oxidative stress is involved in the pathogenesis of the pulmonary fat embolism-induced acute lung injury model in sheep and that the increase relates with the deteriorated oxygenation.

Lipid peroxidation: physiological levels and dual biological effects

Lipid peroxidation (LPO) has been shown to induce disturbance of membrane organization and functional loss and modification of proteins and DNA bases, and it has been implicated in the pathogenesis of various diseases. At the same time, LPO products have been shown to act as redox signaling mediators. Free and ester forms of both polyunsaturated fatty acids and cholesterol are important substrates for LPO in vivo and they are oxidized by both enzymatic and nonenzymatic mechanisms to give a variety of products. The results of numerous studies reported in the literatures show that the levels of LPO products in plasma of healthy human subjects are below 1 muM and that the molar ratios of LPO products to the respective parent lipids are below 1/1000, that is, below 0.1%. The levels of LPO products in human erythrocytes were found to be higher than those in plasma. Considerable levels of cholesterol oxidation products were observed. Although many LPO products exert cytotoxicity, sublethal concentrations of LPO products induce cellular adaptive responses and enhance tolerance against subsequent oxidative stress through upregulation of antioxidant compounds and enzymes. This adaptive response is observed not only for chemically reactive alpha,beta-unsaturated carbonyl compounds such as 4-hydroxy-2-nonenal and 15-deoxy-delta-12,14-prostaglandin J(2) but also for chemically stable compounds such as hydroxyoctadecadienoic acid, hydroxylcholesterol, and lysophosphatidylcholine. Such opposite dual functions of LPO products imply that LPO, and probably oxidative stress in general, may exert both deleterious and beneficial effects in vivo. LPO as well as reactive oxygen and nitrogen species has been shown to play an important role as a regulator of gene expression and cellular signaling messenger. In order to exert physiologically important functions as a regulator of gene expression and mediator of cellular signaling, the formation of LPO products must be strictly controlled and programmed. In contrast to LPO products by enzymatic oxidation, it appears difficult to regulate the formation of free radical-mediated LPO products. Even such unregulated LPO products may exert beneficial effects at low levels, but excessive unregulated LPO may lead to pathological disorders and diseases.

Toxicity studies on depleted uranium in primary rat cortical neurons and in Caenorhabditis elegans: what have we learned?

Depleted uranium (DU) is the major by-product of the uranium enrichment process for its more radioactive isotopes, retaining approximately 60% of its natural radioactivity. Given its properties as a pyrophoric and dense metal, it has been extensively used in armor and ammunitions. Questions have been raised regarding the possible neurotoxic effects of DU in humans based on follow-up studies in Gulf War veterans, where a decrease in neurocognitive behavior in a small population was noted. Additional studies in rodents indicated that DU readily traverses the blood-brain barrier, accumulates in specific brain regions, and results in increased oxidative stress, altered electrophysiological profiles, and sensorimotor deficits. This review summarizes the toxic potential of DU with emphasis on studies on thiol metabolite levels, high-energy phosphate levels, and isoprostane levels in primary rat cortical neurons. Studies in Caenorhabditis elegans detail the role of metallothioneins, small thiol-rich proteins, in protecting against DU exposure. In addition, recent studies also demonstrate that only one of the two forms, metallothionein-1, is important in the accumulation of uranium in worms.

Pharmacological profile of a novel H(2)S-releasing aspirin

The pharmacological profile of a new, safe, and effective hydrogen sulfide (H(2)S)-releasing derivative of aspirin (ACS14) is described. We report the synthesis of ACS14, and of its deacetylated metabolite (ACS21), the preliminary pharmacokinetics, and its in vivo metabolism, with the H(2)S plasma levels after intravenous administration in the rat. ACS14 maintains the thromboxane-suppressing activity of the parent compound, but seems to spare the gastric mucosa, by affecting redox imbalance through increased H(2)S/glutathione formation, heme oxygenase-1 promoter activity, and isoprostane suppression.

Isoprostanes and other markers of peroxidation in atherosclerosis

Several lines of evidence suggest that reactive oxygen species play a role in the development of vasculopathies, including those that define atherosclerosis, hypertension and restenosis after angioplasty. Confused picture emerging from prospective clinical trials of anti-oxidants may reflect inadequacy of traditional indices of lipid peroxidation in the recruitment of appropriate patients and in guiding the selection of the appropriate dose of anti-oxidant to be tested. Ex vivo indices of oxidant stress could have questionable veracity in assessing the actual rate of lipid peroxidation in vivo. The measurement of F(2)-isoprostanes (F(2)-iPs), formed non-enzimatically through free radical catalysed attack on esterified arachidonate, provides a reliable tool for identifying populations with enhanced rates of lipid peroxidation. Enhanced formation of F(2)-iPs, together with increased in vivo platelet activation, has been reported in association with several cardiovascular risk factors. Thus, it has been suggested that F(2)-iPs may transduce oxidant stress-dependent platelet activation. Measurements of 8-iso-PGF(2alpha), an abundant F(2)-iP formed in vivo, in urine may provide sensitive biochemical end-points for the assessment of the oxidant status of the patient and the true efficacy of anti-oxidant therapies. The incorporation of such biochemical end-points in clinical trials may help to verify the reliability of the oxidative modification hypothesis in the development of atherosclerosis.

Influence of lung oxidant and antioxidant status on alveolarization: role of light-exposed total parenteral nutrition

Parenteral multivitamins (MVP) are linked to the generation of peroxides, which cause oxidant injury in lungs associated with alveolar remodelling linked to lung disease of prematurity. This study was to investigate the relationship between alveolar development and lung oxidant-antioxidant status as modulated by the mode of administration of multivitamins with total parenteral nutrition (TPN). Four groups of guinea pig pups received parenteral nutrition differing by 1) mode of MVP admixture: with amino acid solution (AA-MVP) or lipid emulsion (LIP-MVP); 2) light exposure: TPN exposed (LE) or shielded from light (LP). After 2 or 4 days of TPN, vitamins C and E, 8-isoprostaneF2alpha and alveolarization index were determined in lungs and GSSG/GSH in lungs and blood. Exposure to light and the mode of MVP admixture did not influence vitamin E and isoprostane levels. Blood glutathione redox potential was more oxidized in LE and LIP-MVP groups after 4-day infusions, whereas lung redox potential was more reduced in LE groups. LP and LIP-MVP had a beneficial effect, with higher number of alveoli. Globally, results indicate that in this model, alveolarization and modifications in lung redox potential are two independent events induced by light exposed TPN.

F(2)-isoprostanes as biomarkers of late-onset Alzheimer's disease

Alzheimer's disease (AD) is a syndrome caused by a few uncommon mutations that lead to early-onset disease, occurs in adults with Down's syndrome, but is by far most commonly seen as a late-onset disease with multiple risk factors but no causative factors yet identified. Emerging data suggests a chronic disease model for AD with latency, prodrome, and dementia stages together lasting decades. Free radical damage to lipids in brain is one pathogenic process of AD that may be quantified with F(2)-isoprostanes (IsoPs). Whereas brain and cerebrospinal fluid (CSF) F(2)-IsoPs are reproducibly elevated in AD patients at both dementia and prodromal stages of disease, plasma and urine F(2)-IsoPs are not reproducibly increased in AD patients. CSF F(2)-IsoPs may be used to assist in diagnosis and aid in objective assessment of disease progression and response to therapeutics in patients with AD.

Lipid peroxidation products as oxidative stress biomarkers

Oxidative stress induced by reactive oxygen and nitrogen species has been implicated in the pathogenesis of various disorders and diseases. Biomarkers are needed for assessment of oxidative stress status in vivo and also for health examination, diagnosis at early stage, prognosis, safe and efficient drug development, and evaluation of efficacy of drugs, foods, beverages, and supplements. Lipids are susceptible to oxidation and lipid peroxidation products are potential biomarkers for oxidative stress status in vivo and its related diseases. Recently, isoprostane, isoprostaglandin homologues from arachidonic acid, neuroprostanes from docosahexaenoic acid, hydroxyoctadecadienoic acid from linoleic acid, and oxysterols from cholesterol have received much attention as potential biomarkers for oxidative stress status in vivo. The physiological levels of these lipid peroxidation products and potential application as biomarkers will be reviewed.

New techniques to detect oxidative stress markers: mass spectrometry-based methods to detect isoprostanes as the gold standard for oxidative stress in vivo

Free radical-induced lipid oxidation under oxidative stress has been implicated in a number of human diseases. Isoprostanes (IsoPs), isomers of prostaglandins, are one of the major classes of oxidation products derived from this oxidation process. Measurement of the levels of IsoPs by Mass Spectrometry-based methods has become the "gold standard" biomarker of oxidative stress in vivo. Significant advances have been made in understanding this important pathway of lipid peroxidation since the discovery of IsoP formation in vivo 18 years ago. Studies from our laboratory and others are discussed that have provided insights into the mechanism of formation. Furthermore, new independent studies have demonstrated that IsoPs are the most reliable available marker of lipid peroxidation in vivo, and recent work examining IsoP formation has provided valuable information about the pathogenesis of numerous human diseases. Thus, the complexity of the IsoP pathway has expanded, providing novel insights into mechanisms of lipid peroxidation in vivo and allowing investigators to explore the role of oxidative stress in human disease.

Electrophilic cyclopentenone isoprostanes in neurodegeneration

Although oxidative stress has been implicated in the pathogenesis of numerous neurodegenerative conditions, the precise mechanisms by which reactive oxygen species (ROS) induce neuronal death are still being explored. The generation of reactive lipid peroxidation products is thought to contribute to ROS neurotoxicity. Isoprostanes (IsoPs), prostaglandin-like molecules formed in vivo via the ROS-mediated oxidation of arachidonic acid, have been previously demonstrated to be formed in increased amounts in the brains of patients with various neurodegenerative diseases. Recently, we have identified a new class of IsoPs, known as A(2)- and J(2)-IsoPs or cyclopentenone IsoPs, which are highly reactive electrophiles and form adducts with thiol-containing molecules, including cysteine residues in proteins and glutathione. Cyclopentenone IsoPs are favored products of the IsoP pathway in the brain and are formed abundantly after oxidant injury. These compounds also potently induce neuronal apoptosis by a mechanism which involves glutathione depletion, ROS generation, and activation of several redox-sensitive pathways that overlap with those involved in other forms of oxidative neurodegeneration. Cyclopentenone IsoPs also enhance neurodegeneration caused by other insults at biologically relevant concentrations. These data are reviewed, whereas new data demonstrating the neurotoxicity of J-ring IsoPs and a discussion of the possible role of cyclopentenone IsoPs as contributors to neurodegeneration are presented.

Measurement of chronic oxidative and inflammatory stress by quantification of isoketal/levuglandin γ-ketoaldehyde protein adducts using liquid chromatography tandem mass spectrometry

Measurement of F(2)-isoprostanes (F(2)-IsoPs) has been independently verified as one of the most reliable approaches to assess oxidative stress in vivo. However, the rapid clearance of F(2)-IsoPs makes the timing of sample collection critical for short-lived oxidative insults. Isoketals (IsoKs) are gamma-ketoaldehydes formed via the IsoP pathway of lipid peroxidation that rapidly react with lysyl residues of proteins to form stable protein adducts. Oxidative stress can also activate cyclooxygenases to produce prostaglandin H(2), which can form two specific isomers of IsoK-levuglandin (LG) D(2) and E(2). Because adducted proteins are not rapidly cleared, IsoK/LG protein adduct levels can serve as a dosimeter of oxidative and inflammatory damage over prolonged periods of time as well as brief episodes of injury. Quantification of IsoK/LG protein adducts begins with liquid-phase extraction to separate proteins from lipid membranes, allowing measurement of both IsoK/LG protein adducts and F(2)-IsoP from the same sample if desired. IsoK/LG-lysyl-lactam adducts are measured by liquid chromatography tandem mass spectrometry after proteolytic digestion of extracted proteins, solid-phase extraction and preparative HPLC.