Formation of PGF2-Isoprostanes During the Oxidative Modification of Low Density Lipoprotein

doi:10.1006/bbrc.1994.1453

Biochemical and Biophysical Research Communications

Volume 200, Issue 1, 15 April 1994, Pages 338-343

https://doi.org/10.1006/bbrc.1994.1453 Get rights and content

Abstract

It has been recently reported that a series of prostaglandin F₂-like compounds (PGF₂-isoprostanes) are produced in vivo by non-enzymatic peroxidation of arachidonic acid. Of these, 8-epi-PGF_2α is the major component and has been shown to be a potent vasoconstrictor. Here we investigated the formation of PGF₂-isoprostanes during copper-mediated oxidation of low density lipoprotein (LDL). Free and total (sum of free and esterified) levels of PGF₂-isoprostanes were measured at times 0, 3, 6, 8 and 24 h, using a solid-phase extraction procedure and gas chromatography - mass spectrometry. In native LDL, free levels of PGF₂-isoprostanes were between 0.06 and 0.10 ng/mg protein (n = 4), and the total levels ranged from 0.027 to 0.057 ng/mg protein (n = 4). Free levels of the isoprostanes were found to increase throughout the oxidation, whereas total levels reached a maximum after 3 h then gradually decreased. 8-epi-PGF_2α was the major isoprostane formed (free concentration after 24 h 1.8 ± 0.1 ng/mg protein (n = 4); total concentrations of 8.8 ± 1.8 and 6.1 ± 3.6 ng/mg protein (n = 4) after 3 and 24 h, respectively). The levels of isoprostanes correlated well with other indices of lipid peroxidation (conjugated dienes, hydroperoxides, thiobarbituric reactive substances) measured at similar time points. The release of PGF₂-isoprostanes from oxidised LDL in macrophages could be a contributory factor in the development of atherosclerosis.

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Cited by (65)

"Effects of recombinant human erythropoietin high mimicking abuse doses on oxidative stress processes in rats"
2016, Biomedicine and Pharmacotherapy
Citation Excerpt :
Detectable levels of 8-isoPGF2α have been obtained in different body fluids including blood, urine, bile, pericardial fluid, lung condensates and cerebrospinal fluid as well as in different tissues [62,63,64]. The levels of 8-isoPGF2α are increased in LDL by in vitro oxidative modification [66–68]. In animals, the levels of 8-isoPGF2α are increased in models of oxidative stress [66–68], increased with antioxidant deficiency and reduced by dietary antioxidant supplementation [67–73].
Although many studies highlight how long-term moderate dose of Recombinant Human Erythropoietin (rHuEPO) treatments result in beneficial and antioxidants effects, few studies take into account the effects that short-term high doses of rHuEPO (mimicking abuse conditions) might have on the oxidative stress processes. Thus, the aim of this study was to investigate the in vivo antioxidant activity of rHuEPO, administered for a short time and at high doses to mimic its sports abuse as doping. Male Wistar healthy rats (n = 36) were recruited for the study and were treated with three different concentrations of rHuEPO: 7.5, 15, 30 μg/kg. Plasma concentrations of erythropoietin, 8-epi Prostaglandin F_2α, plasma and urinary concentrations of NOx were evaluated with specific assay kit, while hematocrit levels were analyzed with an automated cell counter. Antioxidant activity of rHuEPO was assessed analyzing the possible variation of the plasma scavenger capacity against hydroxylic and peroxylic radicals by TOSC (Total Oxyradical Scavenging Capacity) assay. Statistical analyses showed higher hematocrit values, confirmed by a statistically significant increase of plasmatic EPO concentration. An increase in plasma scavenging capacity against peroxyl and hydroxyl radicals, in 8-isoprostane plasmatic concentrations and in plasmatic and urinary levels of NO_X were also found in all the treated animals, though not always statistically significant. Our results confirm the literature data regarding the antioxidant action of erythropoietin administered at low doses and for short times, whereas they showed an opposite incremental oxidative stress action when erythropoietin is administered at high doses.
Exposure to traffic emissions: Associations with biomarkers of antioxidant status and oxidative damage
2013, Environmental Research
Citation Excerpt :
In particular, as discussed above, the TBARS test does not measure malondialdehyde exclusively and malondialdehyde is also not generated exclusively by breakdown of lipid hydroperoxide (Janero, 1990). However, some experimental studies have shown that good correlations of TBARS with levels of isoprostane, a more specific lipid peroxidation marker (Gopaul et al., 1994; Nourooz-Zadeh et al., 1998). There were also some issues with the available data for potential confounders.
Oxidative stress has been implicated as a possible mechanism for adverse health effects associated with traffic emissions. We examined the association of an estimate of traffic emissions with blood biomarkers of antioxidant capacity (glutathione, glutathione peroxidase, trolox-equivalent antioxidant capacity) and oxidative damage (thiobarbituric acid-reactive substances (TBARS)) among 1810 healthy women, randomly selected from Erie and Niagara Counties in Western New York.
A geographic traffic emission and meteorological dispersion model was used to estimate annual polycyclic aromatic hydrocarbon (PAH) exposure from traffic emissions for each woman based on her residence at the time of study. Associations of traffic-related PAH exposure with measures of oxidative stress and antioxidant capacity were examined in multiple regression analyses with adjustment for potential confounders.
Higher traffic-related PAH exposure was associated with decreased glutathione and increased glutathione peroxidase. Stronger associations between traffic-related PAH exposure and levels of glutathione and glutathione peroxidase were suggested among nonsmoking women without secondhand smoke exposure, especially among premenopausal nonsmoking women. Associations were also stronger for measurements made in warmer months.
These findings suggest that PAHs or other components of traffic emissions may impact anti-oxidative capacity among healthy women, particularly premenopausal non-smokers without secondhand smoke exposure.
Release of free F<inf>2</inf>-isoprostanes from esterified phospholipids is catalyzed by intracellular and plasma platelet-activating factor acetylhydrolases
2006, Journal of Biological Chemistry
F₂-isoprostanes are produced in vivo by nonenzymatic peroxidation of arachidonic acid esterified in phospholipids. Increased urinary and plasma F₂-isoprostane levels are associated with a number of human diseases. These metabolites are regarded as excellent markers of oxidant stress in vivo. Isoprostanes are initially generated in situ, i.e. when the arachidonate precursor is esterified in phospholipids, and they are subsequently released in free form. Although the mechanism(s) responsible for the release of free isoprostanes after in situ generation in membrane phospholipids is, for the most part, unknown, this process is likely mediated by phospholipase A₂ activity(ies). Here we reported that human plasma contains an enzymatic activity that catalyzes this reaction. The activity associates with high density and low density lipoprotein and comigrates with platelet-activating factor (PAF) acetylhydrolase on KBr density gradients. Plasma samples from subjects deficient in PAF acetylhydrolase do not release F₂-isoprostanes from esterified precursors. The intracellular PAF acetylhydrolase II, which shares homology to the plasma enzyme, also catalyzes this reaction. We found that both the intracellular and plasma PAF acetylhydrolases have high affinity for esterified F₂-isoprostanes. However, the rate of esterified F₂-isoprostane hydrolysis is much slower compared with the rate of hydrolysis of other substrates utilized by these enzymes. Studies using PAF acetylhydrolase transgenic mice indicated that these animals have a higher capacity to release F₂-isoprostanes compared with nontransgenic littermates. Our results suggested that PAF acetylhydrolases play key roles in the hydrolysis of F₂-isoprostanes esterified on phospholipids in vivo.
Elevated urinary 8-isoprostaglandin F<inf>2α</inf> in females with Graves' hyperthyroidism
2004, Prostaglandins Leukotrienes and Essential Fatty Acids
In this study, we investigate how oxidative stress alters the urinary F₂-isoprostanes’ level and we examine the correlation between 8-isoPGF_2α and thyroid hormones in female patients with Graves’ hyperthyroidism. We quantitatively determined the concentrations of urinary F₂-isoprostanes using gas chromatography-mass spectrometry in the selected ion-monitoring mode. We recruited individuals in the following three groups of subjects for this study: (1) female hyperthyroidism patients (n=14, 21–71 years), (2) female hypothyroidism patients (n=16, 16–66 years), and (3) female age-matched normal controls (n=10, 20–61 years). The average concentration of 8-iso prostaglandin F_2α (8-isoPGF_2α) in hyperthyroidism patients was significantly higher than that in the healthy controls (P<0.05). The concentration of 8-isoPGF_2α in hypothyroidism patients was similar to that in normal controls. Although the level of 8-isoPGF_2α in two of the patients was slightly elevated, the P value was not significant (NS). Our data suggest that the increased level of urinary 8-isoPGF_2α may reflect possible oxidation injuries in hyperthyroidism patients due to the high level of thyroid hormones. Therefore, the elevated 8-isoPGF_2α in patients could be used as an important biomarker for hyperthyroidism disease.
(Iso) prostaglandins in saliva indicate oxidation injury after radioiodine therapy
2004, Revista Espanola de Medicina Nuclear
As salivary glands concentrate radioiodine the radiation injury associated with ¹³¹I-therapy may result in sialoadenitis and xerostoma leading to a lasting impaired quality of life. Recently we reported about prostaglandin concentration changes as biochemical markers for radiation injury. Isoprostanes, a new family of prostaglandin-like compounds, have been demonstrated to be reliable markers for oxidation injury in vivo.
In this study we examined the levels of 8-epi-PGF_2α, the major member of the isoprostane family in 24 patients undergoing ¹³¹I treatment in different doses for hyperthyroidism and differentiated thyroid cancer. 6 healthy sex and age-matched volunteers were monitored in parallel. Saliva (iso)prostaglandins were determined before ¹³¹I treatment, as well as 1, 3, 7, 14, 21, and 28 days, and 2, 3, and 6 months after therapy.
8-epi-PGF_2α showed a significant 131I dose-dependent temporary increase. The alterations were comparable in all investigated patients and significantly higher in cigarette smokers. TXB₂ and 6-oxo-PGF_2α showed a dose-dependent increase too. TXB2 was higher in cigarette smokers and 6-oxo-PGF1α lower as compared to non-smokers.
These results clearly demonstrate a dose- and time-dependent tissue (TXB₂, 6-oxo-PGF_1α) and oxidation injury (8-epi-PGF_2α) after ¹³¹I-therapy in the salivary glands.
Ya que las glándulas salivares concentran radioyodo, el daño de la radiación asociado a la terapia con ¹³¹I puede dar lugar a sialoadenitis y xerostoma, conduciendo a una calidad de vida dañada de forma duradera. Recientemente, hemos informado sobre cambios en la concentración de prostaglandina como marcadores bioquímicos para daño después de radiación. Se ha demostrado que los isoprostanos, una nueva familia del compuestos del tipo prostaglandina, son marcadores fiables para daño oxidativo in vivo.
En este estudio, exploramos los niveles de 8-epi-PGF_2α, el miembro más importante de la familia de isoprostanos, en 24 pacientes recibiendo tratamiento 131I con dosis diferentes para hipertiroidismo y cáncer de tiroides diferenciados. Fueron monitorizados en paralelo 6 voluntarios sanos pareados por edad y sexo. Se determinaron (iso)prostaglandinas en saliva antes del tratamiento de ¹³¹I, así como 1, 3, 7, 14, 21 y 28 días y 2, 3, y 6 meses después del tratamiento.
8-epi-PGF_2α demostraron un aumento temporal significativo dependiendo de la dosis de ¹³¹I. Las alteraciones en todos los pacientes investigados fueron comparables y significativamente más altas en los que fumaban. TXB2 y 6-oxo- PGF_1α demostraron también un aumento dependiente de la dosis. TXB2 fue más alto en los que fumaban y 6-oxo-PGF_1α más bajo al compararlo con no-fumadores.
Estos resultados demostraron claramente un daño tisular tiempo y dosis dependiente (TXB₂, 6-oxo-PGF_1α) y daño oxidativo (8-epi-PGF_2α) después de terapia con ¹³¹I en las glándulas salivares.
Alteration of plasma total F<inf>2</inf>-isoprostanes before and after hemodialysis in end-stage renal disease patients
2004, Prostaglandins Leukotrienes and Essential Fatty Acids
F₂-isoprostanes are derived in vivo principally from the following: (1) the formation of positional peroxyl radicals of arachidonic acid, (2) endocyclization to prostaglandin G₂-like structures, and (3) reduction to PGF₂-like compounds. F₂-isoprostanes have been proposed as biomarkers of lipid peroxidation, oxidative stress status, and the oxidation of low-density lipoprotein (LDL). Using gas chromatography-ion trap-mass spectrometry, we studied how hemodialysis (HD) affects plasma total F₂-isoprostanes. We examined the plasma total F₂-isoprostanes in end-stage renal disease (ESRD) patients, before HD, after HD, between HD, and in control subjects. Plasma concentrations of total F₂-isoprostanes were significantly higher in the after HD ESRD patients than the before hemodialysis ESRD patients (P<0.05). There is no difference between before HD ESRD patients and normal controls. Moreover, a positive or negative correlation was seen between LDL and plasma total F₂-isoprostanes (P<0.001), and between age and plasma total F₂-isoprostanes (P<0.001). This study indicates HD treatment may be the major contributor of oxidative stress in ESRD patients.

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Regular ArticleFormation of PGF2-Isoprostanes During the Oxidative Modification of Low Density Lipoprotein

Abstract

Regular Article
Formation of PGF₂-Isoprostanes During the Oxidative Modification of Low Density Lipoprotein