Indirect enhancement of neutrophil activity and adhesion to cultured human umbilical vein endothelial cells by isoprostanes (iPF2alpha-III and iPE2-III)

Production profile of lipid mediators in conjunctival lavage fluid in allergic and infectious conjunctivitis in guinea pigs

Introduction

Conjunctivitis is a major ocular disease classified into allergic or infectious. The pathological features of conjunctivitis are not fully understood despite its high morbidity rate; thus, its differentiation can be difficult.

Materials and methods

We used ovalbumin-induced allergic conjunctivitis and lipopolysaccharide-induced infectious conjunctivitis models of guinea pigs. Both models showed conjunctival swelling. Histological studies revealed that numerous eosinophils infiltrated the conjunctiva in the allergic model, whereas neutrophils infiltrated the conjunctiva in the infectious model. We collected conjunctival lavage fluid (COLF) and comprehensively analyzed lipid production using liquid chromatography-tandem mass spectrometry.

Results

COLF showed increase of 20 and 12 lipid species levels in the allergic and infectious models, respectively. Specifically, the levels of a major allergic mediator, prostaglandin D₂ and its three metabolites and several cytochrome P450-catalyzed lipids increased in the allergic model. In the infectious model, the levels of prostaglandin E₂ and 8-iso-prostaglandin E₂ increased, indicating tissue inflammation. Moreover, the level of 12-oxo-eicosatetraenoic acid, a lipoxygenase metabolite, increased in the infectious model.

Conclusion

These differences in lipid production in the COLF reflected the pathological features of allergic and infectious conjunctivitis.

Impact of ROS-Dependent Lipid Metabolism on Psoriasis Pathophysiology

Psoriasis is the most common autoimmune disease, yet its pathophysiology is not fully understood. It is now believed that psoriasis is caused by the increased activation of immune cells, especially Th1 lymphocytes. However, in psoriasis, immune cells interfere with the metabolism of keratinocytes, leading to their increased activation. Therefore, the pathophysiology of psoriasis is currently associated with the overproduction of ROS, which are involved in the activation of immune cells and keratinocytes as well as the modulation of various signaling pathways within them. Nevertheless, ROS modulate the immune system by also boosting the increasing generation of various lipid mediators, such as products of lipid peroxidation as well as endocannabinoids and prostaglandins. In psoriasis, the excessive generation of ROS and lipid mediators is observed in different immune cells, such as granulocytes, dendritic cells, and lymphocytes. All of the above may be activated by ROS and lipid mediators, which leads to inflammation. Nevertheless, ROS and lipid mediators regulate lymphocyte differentiation in favor of Th1 and may also interact directly with keratinocytes, which is also observed in psoriasis. Thus, the analysis of the influence of oxidative stress and its consequences for metabolic changes, including lipidomic ones, in psoriasis may be of diagnostic and therapeutic importance.

Oxidative Stress and Lipid Mediators Modulate Immune Cell Functions in Autoimmune Diseases

Autoimmune diseases, including psoriasis, systemic lupus erythematosus (SLE), and rheumatic arthritis (RA), are caused by a combination of environmental and genetic factors that lead to overactivation of immune cells and chronic inflammation. Since oxidative stress is a common feature of these diseases, which activates leukocytes to intensify inflammation, antioxidants could reduce the severity of these diseases. In addition to activating leukocytes, oxidative stress increases the production of lipid mediators, notably of endocannabinoids and eicosanoids, which are products of enzymatic lipid metabolism that act through specific receptors. Because the anti-inflammatory CB2 receptors are the predominant cannabinoid receptors in leukocytes, endocannabinoids are believed to act as anti-inflammatory factors that regulate compensatory mechanisms in autoimmune diseases. While administration of eicosanoids in vitro leads to the differentiation of lymphocytes into T helper 2 (Th2) cells, eicosanoids are also necessary for the different0iation of Th1 and Th17 cells. Therefore, their antagonists and/or the genetic deletion of their receptors abolish inflammation in animal models of psoriasis—RA and SLE. On the other hand, products of non-enzymatic lipid peroxidation, especially acrolein and 4-hydroxynonenal-protein adducts, mostly generated by an oxidative burst of granulocytes, may enhance inflammation and even acting as autoantigens and extracellular signaling molecules in the vicious circle of autoimmune diseases.

F2-isoprostanes affect macrophage migration and CSF-1 signalling

F₂-isoprostanes (F₂-IsoP) are formed in vivo via free radical peroxidation of arachidonic acid. Enhanced oxidative stress is implicated in the development of atherosclerosis in humans and F₂-IsoP have been detected in atherosclerotic plaque. Colony stimulating factor-1 (CSF-1) is essential to macrophage survival, proliferation and differentiation and has been detected in human atherosclerotic plaques. Accumulation of macrophages within the vascular wall is an important component of atherosclerosis but little is known about the effect of F₂-IsoP on the migration of these cells. Our aim was to examine the effect of free and lipid-bound 15-F_2t-isoprostane (15-F_2t-IsoP) on macrophage migration and investigate the signalling pathways involved. Mouse macrophages (cell line BAC1.2F5) were pre-incubated with 15-F_2t-IsoP (free, bound to cholesterol or monoacylglycerol or within oxidized phospholipid) and cell migration was assessed using chemotaxis towards CSF-1 in Boyden chambers. Migration was also measured using the wound healing assay with primary mouse bone marrow derived macrophages. We showed that 15-F_2t-IsoP dose-dependently inhibited BAC1.2F5 macrophage spreading and adhesion but stimulated their migration towards CSF-1, with maximum effect at 10 µM. Analysis of CSF-1 stimulated signalling pathways in BAC1.2F5 macrophages showed that phosphorylation of Akt, a key mediator of cell migration, and one of its regulators, the mTORC2 component, Rictor, was significantly decreased. In contrast, phosphorylation of the adhesion kinases, FAK and Pyk2, and the adhesion scaffold protein, paxillin, was enhanced after treatment with 15-F_2t-IsoP. Mouse bone marrow macrophages were transfected with FAK or Pyk2 small interfering RNA (siRNA) to examine the role of FAK and Pyk2 in 15-F_2t-IsoP signalling. Pyk2 silencing inhibited 15-F_2t-IsoP-induced reduction in cell area and phospho-paxillin adhesion numbers. The size distribution of adhesions in the presence of 15-F_2t-IsoP was also affected by Pyk2 silencing and there was a trend for Pyk2 silencing to reduce 15-F_2t-IsoP-stimulated macrophage migration. These results demonstrate that 15-F_2t-IsoP affects macrophage adhesions and migration, which are integral components of macrophage involvement in atherosclerosis.

Elevated 8-Isoprostane Levels in Basal Cell Carcinoma and in Uva Irradiated Skin

Isoprostanes are prostaglandin isomers produced from the peroxidation of polyunsaturated fatty acids from the cellular membrane. They have been used as a specific index of cellular lipoperoxidation and as an indirect measure of oxidative stress. However, these molecules also present several biological activities. An oxidative environment measured as the presence of other indirect measurements of reactive oxygen species lipoperoxidation has recently been described in basal cell carcinoma, the most frequent type of non-melanoma skin cancer. This study aims to measure the levels of 8-isoprostaglandin F2α, an isoprostane widely studied in other models as a by-product of ROS-induced lipid peroxidation, in basal cell carcinoma and in UVA irradiated healthy skin. We found that 8-iso-PGF2α is present in higher levels in BCC specimens compared to healthy non sun-exposed skin, confirming previous studies on the production of lipoperoxidation in this tumor. Moreover, we demonstrated that topical pre-treatment with a compound containing vitamin E is capable of reducing 8-iso-PGF2α formation in UV irradiated skin suggesting a role for isoprostanes in UV induced inflammation and eventually carcinogenesis and confirming the function of vitamin E as an antioxidant in this model.

Pathophysiology of isoprostanes in the cardiovascular system: implications of isoprostane-mediated thromboxane A2 receptor activation

Isoprostanes are free radical-catalysed PG-like products of unsaturated fatty acids, such as arachidonic acid, which are widely recognized as reliable markers of systemic lipid peroxidation and oxidative stress in vivo. Moreover, activation of enzymes, such as COX-2, may contribute to isoprostane formation. Indeed, formation of isoprostanes is considerably increased in various diseases which have been linked to oxidative stress, such as cardiovascular disease (CVD), and may predict the atherosclerotic burden and the risk of cardiovascular complications in the latter patients. In addition, several isoprostanes may directly contribute to the functional consequences of oxidant stress via activation of the TxA2 prostanoid receptor (TP), for example, by affecting endothelial cell function and regeneration, vascular tone, haemostasis and ischaemia/reperfusion injury. In this context, experimental and clinical data suggest that selected isoprostanes may represent important alternative activators of the TP receptor when endogenous TxA2 levels are low, for example, in aspirin-treated individuals with CVD. In this review, we will summarize the current understanding of isoprostane formation, biochemistry and (patho) physiology in the cardiovascular context.

Increased susceptibility to hyperoxic lung injury and alveolar simplification in newborn rats by prenatal administration of benzo[a]pyrene

Maternal smoking is one of the risk factors for preterm birth and for the development of bronchopulmonary dysplasia (BPD). In this study, we tested the hypothesis that prenatal exposure of rats to benzo[a]pyrene (BP), a component of cigarette smoke, will result in increased susceptibility of newborns to oxygen-mediated lung injury and alveolar simplification, and that cytochrome P450 (CYP)1A and 1B1 enzymes and oxidative stress mechanistically contribute to this phenomenon. Timed pregnant Fisher 344 rats were administered BP (25 mg/kg) or the vehicle corn oil (CO) on gestational days 18, 19 and 20, and newborn rats were either maintained in room air or exposed to hyperoxia (85% O2) for 7 or 14 days. Hyperoxic newborn rats prenatally exposed to the vehicle CO showed lung injury and alveolar simplification, and inflammation, and these effects were potentiated in rats that were prenatally exposed to BP. Prenatal exposure to BP, followed by hyperoxia, also resulted in significant modulation of hepatic and pulmonary cytochrome P450 (CYP)1A and 1B1 enzymes at PND 7-14. These rats displayed significant oxidative stress in lungs at postnatal day (PND) 14, as evidenced by increased levels of the F2-isoprostane 8-iso-PGF2α. Furthermore, these animals showed BP-derived DNA adducts and oxidative DNA adducts in the lung. In conclusion, our results show increased susceptibility of newborns to oxygen-mediated lung injury and alveolar simplification following maternal exposure to BP, and our results suggest that modulation of CYP1A/1B1 enzymes, increases in oxidative stress, and BP-DNA adducts contributed to this phenomenon.

Biochemical pathogenesis of aspirin exacerbated respiratory disease (AERD)

Aspirin exacerbated respiratory disease (AERD) is a distinct clinical entity characterized by eosinophilic rhinosinusitis, asthma and often nasal polyposis. Exposure to aspirin or other nonsteroid anti-inflammatory drugs (NSAIDs) exacerbates bronchospasms with asthma and rhinitis. Disease progression suggests a skewing towards TH2 type cellular response along with moderate to severe eosinophil and mast cell infiltration. Alterations in upper and lower airway cellular milieu with abnormalities in eicosanoid metabolism and altered eicosanoid receptor expression are the key features underlying AERD pathogenesis. Dysregulation of arachidonic acid (AA) metabolism, notably reduced prostaglandin E2 (PGE2) synthesis compared to their aspirin tolerant counterpart and relatively increased PGD2 production, a TH2/eosinophil chemoattractant are reported in AERD. Underproduced PGE2 is metabolized by overexpression of 15 prostaglandin dehydrogenase (15-PGDH) to inactive products further reducing PGE2 at real time. This relives the inhibitory effect of PGE2 on 5-lipoxygenase (5-LOX) resulting in overproduction of cysteinyl leukotrienes (CysLTs). Diminished formation of CysLT antagonists called lipoxins (LXs) also augments CysLTs responsiveness. Occasional intake of NSAIDs favors even more 5-LOX product formation, further narrowing the bronchoconstrictive bottle neck, resulting in acute asthmatic exacerbations along with increased mucus production. This review focuses on abnormalities in biochemical and molecular mechanisms in eicosanoid biosynthesis, eicosanoid receptor dysregulation and associated polymorphisms with special reference to arachidonic acid metabolism in AERD.

Implications of urine F2-isoprostane metabolite concentration in horses with colic and its potential use as a predictor for surgical intervention

REASONS FOR PERFORMING STUDY

F2-isoprostanes have been used extensively to quantify lipid peroxidation in association with risk factors in various diseases. Horses with colic may have intestinal ischaemia and/or inflammation characterised by oxidative stress and increased production of isoprostanes.

OBJECTIVES

To gather preliminary data regarding the feasibility of using urine F2-isoprostanes and isoprostane metabolites as early screening tools for the presence of gastrointestinal disease requiring surgical intervention in horses and ultimately develop a stall-side test capable of identifying these horses as early as possible for timely referral.

METHODS

Concentrations of urine isoprostane and isoprostane metabolite were determined by mass spectroscopy and normalised to urine creatinine (Cr) concentrations in urine samples from 42 healthy control horses and 43 horses with gastrointestinal pain or colic.

RESULTS

Horses with colic were treated medically (n = 21) or surgically (n = 22). Mean ± s.d. concentrations of urine isoprostane and isoprostane metabolite were significantly higher in horses with colic (2.94 ± 1.69 and 0.31 ± 0.22 ng/mg Cr, respectively), compared to control horses (1.89 ± 1.39 and 0.22 ± 0.08 ng/mg Cr, respectively). Mean urine isoprostane metabolite concentrations were significantly higher in horses undergoing surgery (0.38 ± 0.28 ng/mg Cr) compared to controls and medical colics (0.26 ± 0.11 ng/mg Cr). Nonsurvivors had significantly higher mean urine isoprostane metabolite concentrations (0.47 ± 0.39 ng/mg Cr) than control or surviving colic horses (0.29 ± 0.24 ng/mg Cr).

CONCLUSIONS

Measurement of urine isoprostane metabolite concentration may be a useful prognostic indicator in equine colic.

POTENTIAL RELEVANCE

Urine isoprostane metabolites may aid in early recognition of surgical colic. Isoprostanes are a potential therapeutic target to prevent further systemic and gastrointestinal tissue injury in horses with colic.

A review of experimental evidence linking neurotoxic organophosphorus compounds and inflammation

Organophosphorus (OP) nerve agents and pesticides inhibit acetylcholinesterase (AChE), and this is thought to be a primary mechanism mediating the neurotoxicity of these compounds. However, a number of observations suggest that mechanisms other than or in addition to AChE inhibition contribute to OP neurotoxicity. There is significant experimental evidence that acute OP intoxication elicits a robust inflammatory response, and emerging evidence suggests that chronic repeated low-level OP exposure also upregulates inflammatory mediators. A critical question that is just beginning to be addressed experimentally is the pathophysiologic relevance of inflammation in either acute or chronic OP intoxication. The goal of this article is to provide a brief review of the current status of our knowledge linking inflammation to OP intoxication, and to discuss the implications of these findings in the context of therapeutic and diagnostic approaches to OP neurotoxicity.

Prenatal administration of the cytochrome P4501A inducer, Β-naphthoflavone (BNF), attenuates hyperoxic lung injury in newborn mice: implications for bronchopulmonary dysplasia (BPD) in premature infants

Supplemental oxygen contributes to the development of bronchopulmonary dysplasia (BPD) in premature infants. In this investigation, we tested the hypothesis that prenatal treatment of pregnant mice (C57BL/6J) with the cytochrome P450 (CYP)1A1 inducer, ß-napthoflavone (BNF), will lead to attenuation of lung injury in newborns (delivered from these dams) exposed to hyperoxia by mechanisms entailing transplacental induction of hepatic and pulmonary CYP1A enzymes. Pregnant mice were administered the vehicle corn oil (CO) or BNF (40 mg/kg), i.p., once daily for 3 days on gestational days (17-19), and newborns delivered from the mothers were either maintained in room air or exposed to hyperoxia (>95% O(2)) for 1-5 days. After 3-5 days of hyperoxia, the lungs of CO-treated mice showed neutrophil infiltration, pulmonary edema, and perivascular inflammation. On the other hand, BNF-pretreated neonatal mice showed decreased susceptibility to hyperoxic lung injury. These mice displayed marked induction of ethoxyresorufin O-deethylase (EROD) (CYP1A1) and methoxyresorufin O-demethylase (MROD) (CYP1A2) activities, and levels of the corresponding apoproteins and mRNA levels until PND 3 in liver, while CYP1A1 expression alone was augmented in the lung. Prenatal BNF did not significantly alter gene expression of pulmonary NAD(P)H quinone reductase (NQO1). Hyperoxia for 24-72 h resulted in increased pulmonary levels of the F(2)-isoprostane 8-iso-PGF(2α), whose levels were decreased in mice prenatally exposed to BNF. In conclusion, our results suggest that prenatal BNF protects newborns against hyperoxic lung injury, presumably by detoxification of lipid hydroperoxides by CYP1A enzymes, a phenomenon that has implications for prevention of BPD in infants.

Isoprostanes and asthma

Isoprostanes are prostaglandin (PG)-like compounds generated in vivo following oxidative stress by non-enzymatic peroxidation of polyunsaturated fatty acids, including arachidonic acid. They are named based on their prostane ring structure and by the localization of hydroxyl groups on the carbon side chain; these structural differences result in a broad array of isoprostane molecules with varying biological properties. Generation of specific isoprostanes is also regulated by host cell redox conditions; reducing conditions favor F₂-isoprostane production while under conditions with deficient antioxidant capacity, D₂- and E₂-isoprostanes are formed. F₂-isoprostanes (F₂-isoP) are considered reliable markers of oxidative stress in pulmonary diseases including asthma. Importantly, F₂-isoP and other isoprostanes function as ligands for PG receptors, and potentially other receptors that have not yet been identified. They have been reported to have important biological properties in many organs. In the lung, isoprostanes regulate cellular processes affecting airway smooth muscle tone, neural secretion, epithelial ion flux, endothelial cell adhesion and permeability, and macrophage adhesion and function. In this review, we will summarize the evidence that F₂-isoP functions as a marker of oxidative stress in asthma, and that F₂-isoP and other isoprostanes exert biological effects that contribute to the pathogenesis of asthma. This article is part of a Special Issue entitled Biochemistry of Asthma.

Thromboxane prostanoid receptor stimulation induces shedding of the transmembrane chemokine CX3CL1 yet enhances CX3CL1-dependent leukocyte adhesion

In atherosclerosis, chemokines recruit circulating mononuclear leukocytes to the vascular wall. A key factor is CX3CL1, a chemokine with soluble and transmembrane species that acts as both a chemoattractant and an adhesion molecule. Thromboxane A2 and its receptor, TP, are also critical to atherogenesis by promoting vascular inflammation and consequent leukocyte recruitment. We examined the effects of TP stimulation on processing and function of CX3CL1, using CX3CL1-expressing human ECV-304 cells and primary human vascular endothelial cells. TP agonists promoted rapid shedding of cell surface CX3CL1, which was inhibited by pharmacological inhibitors or specific small interfering RNA targeting tumor necrosis factor-α-converting enzyme (TACE). Because it reduced cell surface CX3CL1, we predicted that TP stimulation would inhibit adhesion of leukocytes expressing the CX3CL1 cognate receptor but, paradoxically, saw enhanced adhesion. We questioned whether the enhanced ability of the remaining membrane-associated CX3CL1 to bind targets was caused by changes in its lateral mobility. Using fluorescence recovery after photobleaching, we found that plasmalemmal CX3CL1 was initially tethered but ultimately mobilized by TP agonists. TP stimulation provoked clustering of transmembrane CX3CL1 at sites of contact with adherent leukocytes. These data demonstrate that TP stimulation induces two distinct effects: a rapid cleavage of surface CX3CL1, thereby releasing the soluble chemoattractant, plus mobilization of the remaining transmembrane CX3CL1 to enhance the avidity of interactions with adherent leukocytes. The dual effect of TP allows CX3CL1 to recruit leukocytes to sites of vascular inflammation while enhancing their adhesion once recruited.

Relationship between oxidative stress-related biomarkers and antioxidant status with asthma and atopy in young adults: a population-based study

BACKGROUND AND AIM

Enhanced oxidative stress has been described in adults who suffer from symptoms of asthma and poor lung function. This study assessed the relation between markers of oxidative stress and antioxidant status and lung function, symptoms of asthma, atopy and bronchial hyperresponsiveness (BHR) in young adults.

METHODS

A sub-sample of 589 individuals aged 22-28 years, selected from a total of 1232 included in a survey assessing early and current risk factors for chronic diseases, participated in the study. Participants were from an agricultural area of Chile, responded to a Spanish version of the European Community Respiratory Health Survey questionnaire, were skin tested to eight allergens, and challenged with methacholine to assess BHR. Five hundred and eighty-five individuals had measures of plasma biomarkers ferric reducing ability of plasma, uric acid, protein carbonyls and 564 had 8-iso-prostaglandin F(2alpha) (8-iso-PGF(2alpha)) assessed.

RESULTS

All participants had detectable plasma 8-iso-PGF(2alpha) and carbonyl levels. There was no indication for an association between markers of antioxidant status or oxidative stress with any of the outcomes studied.

CONCLUSION

The levels of oxidative stress-related biomarkers and antioxidant status in plasma may not be related to asthma in the general population in the absence of more severe symptoms or exacerbations.

8-iso-PGE2Stimulates Anion Efflux from Airway Epithelial Cells via the EP4Prostanoid Receptor

Isoprostanes are biologically active molecules, produced when reactive oxygen species mediate the peroxidation of membrane polyunsaturated fatty acids. Previous work has demonstrated that the isoprostane 8-iso-prostaglandin E(2) (PGE(2)) stimulates cystic fibrosis transmembrane conductance regulator (CFTR)-mediated transepithelial anion secretion across the human airway epithelial cell line, Calu-3. Since isoprostanes predominantly achieve their effects via binding to prostanoid receptors, we hypothesized that this 8-iso-PGE(2) stimulation of CFTR activity was the result of the isoprostane binding to a prostanoid receptor. Using RT-PCR, immunoblotting, and immunofluorescence, we here demonstrate that Calu-3 cells express the EP(1-4) and FP receptors, and localize these proteins in polarized cell monolayers. Using iodide efflux as a marker for CFTR-mediated Cl(-) efflux, we investigate whether prostanoid receptor agonists elicit a functional response from Calu-3 cells. Application of the agonists PGE(2), misoprostol (EP(2), EP(3), and EP(4)) and PGE(1)-OH (EP(3) and EP(4)) stimulate iodide efflux; however, iloprost, butaprost, sulprostone, and fluoprostenol (agonists of the EP(1), EP(2), EP(3), and FP receptors, respectively) have no effect. The iodide efflux seen with 8-iso-PGE(2) is abolished by the EP(4) receptor antagonist AH23848, the CFTR inhibitor 172, and inhibition of PKA and the PI3K pathway. In conclusion, we demonstrate that although Calu-3 cells possess numerous prostanoid receptors, only the EP(4) subtype appears capable of eliciting a functional iodide efflux response, which is mediated via the EP(4) receptor. We propose that 8-iso-PGE(2), acting via EP(4) receptor, could play an important role in the CFTR-mediated response to oxidant stress, and which would be compromised in the CF airways.

E-Ring Isoprostanes Stimulate a Cl Conductance in Airway Epithelium via Prostaglandin E2-Selective Prostanoid Receptors

Isoprostanes comprise a class of membrane lipid metabolites produced during oxidative stress, including asthma, chronic obstructive pulmonary disease, and cystic fibrosis. They are widely recognized to evoke a variety of biological responses in airway and pulmonary vascular smooth muscle, lymphatics, and innervation. However, their effects on airway epithelium are largely unstudied. We examined the electrophysiological responses evoked by several different isoprostane species in bovine airway epithelium using the Ussing chamber technique. The E-ring isoprostanes 15-E(1t)-IsoP and 15-E(2t)-IsoP evoked a substantial increase in short-circuit current (I(SC)), whereas four different F-ring isomers were ineffective. 15-E(2t)-IsoP-evoked I(SC) was mimicked by the prostaglandin E(2)-selective prostanoid receptor (EP)-agonist prostaglandin E(2) but not by agonists of EP(1)/EP(3)-, FP-, or TP receptors (sulprostone, fluprostenol, and U46619, respectively). This response was significantly reduced by the EP(4)-receptor blocker GW627386 but not by blockers of other prostanoid receptors (ICI 192,605 [TP-selective], SC19220 [EP(1)-selective], AH6809 [DP/EP(1)/EP(2)-selective], and AL8810 [FP-selective]). 15-E(2t)-IsoP-evoked I(SC) was reduced by blockers of Cl(-) channels (niflumic acid and 5-nitro-2-(3-phenylpropylamino)-benzoic acid), of Na(+)/K(+)/2Cl(-) co-transport (furosemide and bumetanide), of adenylate cyclase (MDL 12,330A), or of guanylate cyclase (1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one) but not by blockers of Na(+) conductances (amiloride). We conclude that 15-E(2t)-IsoP activates a transepithelial Cl(-) conductance in bovine airway epithelium through an EP(4) receptor coupled to adenylate cyclase and soluble guanylate cyclase.

E-ring isoprostane augments cholinergic neurotransmission in bovine trachealis via FP prostanoid receptors

Isoprostanes are prostaglandin-like molecules that accumulate in oxidative stress and also exert powerful biological effects on a wide variety of tissues. We investigated the effects of several different isoprostanes on contractions evoked by electrical field stimulation (EFS) in bovine trachealis, finding only 15-E2t-IsoP to augment those responses. Many others have shown that isoprostanes act on prostanoid receptors, usually those of the thromboxane-selective prostanoid receptor (TP) subtype, although some describe actions through prostaglandin E2-selective prostanoid receptor (EP) or less frequently through prostaglandin F2alpha-selective prostanoid receptors (FP). We used an extensive panel of highly selective agonists and antagonists of prostanoid receptors to characterize the ones through which 15-E2t-IsoP was acting here. Pretreatment with the FP-selective AL-8810 significantly inhibited the augmentation, whereas TP- and EP-selective blockers did not. On the other hand, the augmentation exerted by 15-E2t-IsoP was mimicked by submicromolar concentrations of the FP-selective agonists PGF2alpha and fluprostenol, as well as by micromolar concentrations of the TP-selective agonist U46619. The concentration-response relationship for exogenously added acetylcholine was not significantly affected by 15-E2t-IsoP, confirming that the effect of the latter on EFS-evoked responses was exerted prejunctionally (i.e., to enhance release of Ach from nerve endings), rather than a direct postjunctional effect via a receptor on the smooth muscle. Finally, we investigated whether the inhibitory (adrenergic) innervation was also modulated by 15-E2t-IsoP, finding EFS-evoked relaxations to be unaffected by the isoprostane. We conclude that 15-E2t-IsoP acts upon an FP receptor on the cholinergic nerve endings, leading to enhanced neurotransmission.

Age-related loss of associations between acute exercise-induced IL-6 and oxidative stress

IL-6 mediates many aspects of the exercise-induced acute-phase response, including upregulation of antioxidant defenses. Moreover, IL-6 synthesis is regulated in part by oxidative stress. This investigation tested the hypothesis that an IL-6-mediated acute-phase response after exercise provides negative-feedback protection against exercise-induced oxidative stress. Healthy young (n = 16, 26.4 +/- 1.8 yr) and older men (n = 16, 71.1 +/- 2.0 yr) ran downhill for 45 min at 75% maximal oxygen consumption before and after a 12-wk period of supplementation with vitamin E (1,000 IU/day) or placebo. Circulating IL-6 and soluble IL-6 receptors, peripheral mononuclear cell production of IL-6, and IL-6 transcripts in muscle were measured before and within a 72-h time window after each acute exercise bout. At all time points plasma IL-6, IL-6 bioavailability, and C-reactive protein were higher in the older men; yet in response to exercise, young and older subjects experienced similar increases in these factors. Although the magnitude of postexercise changes in acute-phase variables was independent of age, correlations among plasma, mononuclear cell, and muscle IL-6 and oxidative stress were evident only in young men (R2 = 0.64, 0.35, and 0.33, respectively). These changes in circulating IL-6 were closely associated with a prooxidant state (R2 = 0.47), whereas muscle IL-6 mRNA correlated with an antioxidant state (R2 = 0.65). Supplementation with vitamin E did not affect exercise-induced responses or differences between the young and old men in a consistent manner. Therefore, oxidative stress is linked to the acute-phase response after exercise in young men, but not in older men who had elevated acute-phase reactants, suggesting that further research is warranted to determine the basis for these differences.

F2-isoprostanes as markers of oxidative stress in vivo: an overview

The isoprostanes are a unique series of prostaglandin-like compounds formed in vivo via a non-enzymatic mechanism involving the free radical-initiated peroxidation of arachidonic acid. This article summarizes selected aspects regarding current knowledge of these compounds and their value as markers of oxidative injury. Novel aspects related to the biochemistry of isoprostane formation are discussed and methods by which these compounds can be analysed and quantified are summarized. A considerable portion of this article examines the utility of F(2)-isoprostanes as markers of oxidant injury in vivo. Numerous studies carried out over the past decade have shown that these compounds are extremely accurate measures of lipid peroxidation and have illuminated the role of oxidant injury in a number of human diseases including atherosclerosis, Alzheimer's disease and pulmonary disorders.

Attenuation of hyperoxic lung injury by the CYP1A inducer beta-naphthoflavone

Supplemental oxygen, frequently used in premature infants, has been implicated in the development of bronchopulmonary dysplasia (BPD). While the mechanisms of oxygen-induced lung injury are not known, reactive oxygen species (ROS) are most likely involved in the process. Here, we tested the hypothesis that upregulation of cytochrome P450 (CYP) 1A isoforms in lung and liver may lead to protection against hyperoxic lung injury. Adult male Sprague-Dawley rats were pretreated with the CYP1A inducer beta-naphthoflavone (beta-NF) (80 mg/kg/day), once daily for 4 days, followed by exposure to hyperoxic environment (O2 > 95%) or room air (normoxia) for 60 h. Pleural effusions were measured as estimates of lung injury. Activities of hepatic and pulmonary CYP1A1 were determined by measurement of ethoxyresorufin O-deethylation (EROD) activity. Northern hybridization and Western blot analysis of lung and liver were performed to assess mRNA and protein levels, respectively. Our results showed that beta-NF-treated animals, which displayed the highest pulmonary and hepatic induction in EROD activity (10-fold and 8-fold increase over corn oil (CO) controls, respectively), offered the most protective effect against hyperoxic lung injury, p < 0.05. Northern and Western blot analysis correlated well with enzyme activities. Our results showed an inverse correlation between pulmonary and hepatic CYP1A expression and the extent of lung injury, which supports the hypothesis that CYP1A enzyme plays a protective role against oxygen-mediated tissue damage.

The isoprostane 8-iso-PGF2alpha suppresses monocyte adhesion to human microvascular endothelial cells via two independent mechanisms

Isoprostanes, produced in vivo by non-enzymatic free-radical-induced lipid peroxidation, are markers of oxidative stress. Elevated serum and urine levels of 8-iso-PGF2alpha have been reported in a variety of diseases, many of which are characterized by early perivascular inflammatory infiltrates. It has been suggested that, in addition to being markers of oxidative stress, isoprostanes may have pathogenic functions. In this study, we investigated the potential role of 8-iso-PGF2alpha in inflammation, focusing on its effects on adhesion of monocytes to microvascular endothelial cells, an early event in the inflammatory response. In monocyte adhesion assays, 8-iso-PGF2alpha (>10(-8) M) suppressed both basal and TNF-alpha-induced monocyte adhesion to quiescent or proliferating human dermal (HMEC) and rat renal microvascular endothelial cells. In contrast, 8-iso-PGF2alpha stimulated monocyte adhesion to human umbilical vein endothelial cells (HUVEC) as also reported by others. 8-Iso-PGF2alpha had no effect on the viability (Trypan Blue exclusion) of U937 monocytes or HMEC. 8-Iso-PGF2alpha also had no effect on HMEC surface expression of ICAM-1 or VCAM-1. Exposure of HMEC to 8-iso-PGF2alpha for 1-2 h was sufficient to reduce monocyte adhesion to the cell surface, and this effect was independent of de novo protein synthesis by HMEC. The effect of 8-iso-PGF2alpha was mimicked by a thromboxane receptor (TP) agonist (U46619) and blocked by a TP antagonist (SQ29548), indicating a TP-mediated process. Signal transduction pathway inhibitors (SB203580, curcumin, and PD98059) implicated p38 and JNK, but not ERK, in 8-iso-PGF2alpha-induced suppression of monocyte adhesion. In addition to a direct effect, conditioned medium (CM) transfer experiments suggest that 8-iso-PGF2alpha induces a secondary mediator, which also suppresses monocyte adhesion but via an alternative mechanism initiated between 3-4 h, which is TP-independent, requires new protein synthesis, and is primarily dependent on activation of p38. The data show that 8-iso-PGF2alpha can suppress the attachment of monocytes to HMECs via two independent pathways, indicating a potential anti-inflammatory effect of 8-iso-PGF2alpha in the microvasculature.

The pulmonary biology of isoprostanes

Isoprostanes were first recognized as convenient markers of oxidative stress, but their powerful effects on a variety of cell functions are now also being increasingly appreciated. This is particularly true of the lung, which is comprised of a wide variety of different cell types (smooth muscle, innervation, epithelium, lymphatics, etc.), all of which have been shown to respond to exogenously applied isoprostanes. In this review, we summarize these biological responses in the lung, and also consider the roles that isoprostanes might play in a range of pulmonary clinical disorders.

E-ring 8-isoprostanes are agonists at EP2- and EP4-prostanoid receptors on human airway smooth muscle cells and regulate the release of colony-stimulating factors by activating cAMP-dependent protein kinase

8-Isoprostanes are bioactive lipid mediators formed via the nonenzymatic peroxidation of arachidonic acid by free radicals and reactive oxygen species. However, their cognate receptors, biological actions, and signaling pathways are poorly studied. Here, we report the effect of a variety of E- and Falpha-ring 8-isoprostanes on the release of granulocyte/macrophage colony-stimulating factor (GM-CSF) and granulocyte colony-stimulating factor (G-CSF) from human airway smooth muscle (HASM) cells stimulated with interleukin-1beta (IL-1beta). The elaboration of GM-CSF and G-CSF by IL-1beta was inhibited and augmented, respectively, in a concentration-dependent manner by 8-iso-prostaglandin (PG) E(1) and 8-iso-PGE(2), but not by 8-iso-PGF(1alpha), 8-iso-PGF(2alpha), and 8-iso-PGF(3)alpha. AH 6809 (6-isopropoxy-9-oxoxanthine-2-carboxylic acid), an EP(1)-/EP(2)-/DP-receptor blocking drug, antagonized the inhibitory effect of 8-iso-PGE(1) and 8-iso-PGE(2) on GM-CSF output with an affinity consistent with an interaction at prostanoid receptors of the EP(2)-subtype. In contrast, the facilitation by 8-iso-PGE(1) and 8-iso-PGE(2) of G-CSF release was unaffected by AH 6809 and the selective EP(4)-receptor antagonist L-161,982 [4'-[3-butyl-5-oxo-1-(2-trifluoromethyl-phenyl)-1,5-dihydro-[1,2,4]triazol-4-ylmethyl]-biphenyl-2-sulfonic acid (3-methyl-thiophene-2-carbonyl)-amide]. However, when used in combination, AH 6809 and L-161,982 displaced 5-fold to the right the 8-iso-PGE and 8-iso-PGE concentration-response curves. The opposing (1)effect of E-ring (2)8-isoprostanes on GM-CSF and G-CSF release was mimicked by 8-bromo-cAMP and abolished in cells infected with an adenovirus vector encoding an inhibitor protein of cAMP-dependent protein kinase (PKA). Together, these data demonstrate that E-ring 8-isoprostanes regulate the secretion of GM-CSF and G-CSF from HASM cells by a cAMP- and PKA-dependent mechanism. Moreover, antagonist studies revealed that 8-iso-PGE(1) and 8-iso-PGE(2) act solely via EP(2) -receptors to inhibit GM-CSF release, whereas both EP(2)- and EP(4)-receptor subtypes positively regulate G-CSF output.

Revascularization decreases 8-isoprostaglandin F2alpha excretion in chronic lower limb ischemia

8-Isoprostaglandin F2alpha is one of a series of isoprostanes formed by free radical catalysed peroxidation of arachidonic acid. Urinary 8-isoprostaglandin F2alpha is a new marker which reflects oxidative stress in vivo and can be utilized as a diagnostic tool to assess the extent of oxidative stress in various disease states associated with lipid peroxidation. Increased levels of 8-isoprostaglandin F2alpha in cardiac ischemia/reperfusion provide evidence for oxidative stress during coronary perfusion. In animal studies, the restoration of blood flow after lower limb ischemia is followed by reperfusion syndrome. In this study we investigated whether lower limb ischemia/reperfusion is associated with oxidative stress, as reflected by urinary levels of 8-isoprostaglandin F2alpha. Ten patients (mean age 72 years, range 61-82 years) suffering from chronic lower limb ischemia and 10 healthy volunteers (mean age 69 years, range 60-79 years) participated in the study. In all patients, diagnostic angiography had revealed stenosis or occlusion either in the aortoiliac or femoropopliteal region. Surgical revascularization consisted of femoropopliteal reconstruction, femorofemoral reconstruction, aortobifemorial reconstruction, or femoral endartectomy. Urine samples from patients were collected a day before surgery and in the second postoperative day. Urinary 8-isoprostaglandin F2alpha was extracted on a C2 silica cartridge and determinated by radioimmunoassay. After revascularization, 8-isoprostaglandin F2alpha excretion (pg/micromol creatinine, mean +/- SD) was decreased by 2.5-fold (preoperative 48.9 +/- 8.9, postoperative 19.1 +/- 9.5, P < 0.001). The postoperative values were similar to the concentrations measured in healthy volunteers (18.0 +/- 11.0). All revascularizations were successful, and the increase in ankle-brachial index (preoperative 0-0.6, postoperative 0.4-0.8) revealed improved blood flow in the ischemic lower limb. We suggest that, as assessed by the quantitation of urinary 8-isoprostaglandin F2alpha, chronic lower limb ischemia is associated with increased oxidative stress, which is decreased by revascularization.

The pulmonary biology of isoprostanes

Isoprostanes are widely recognized as useful markers of membrane lipid peroxidation. It seems to be less well appreciated, however, that they also elicit important biological responses, even though this was first shown at the same time that they were introduced as markers of oxidative stress. The past several years have seen the list of cells/tissues which are sensitive to isoprostanes grow considerably: in fact, as we summarize here, there is now evidence that essentially every cell type in the lung responds in some pathologically relevant way to isoprostanes. In this sense, they might well be considered as not just markers of oxidative stress and inflammation, but also as a novel group of inflammatory mediators. Moreover, in addition to their pathological effects, we summarize here the evidence which has led us to hypothesize that isoprostanes could play an important role in vascular smooth muscle physiology as "endothelium-derived hyperpolarizing factors."

E-ring 8-isoprostanes inhibit ACh release from parasympathetic nerves innervating guinea-pig trachea through agonism of prostanoid receptors of the EP3-subtype

1. In the present study, we examined the effect of E-ring 8-isoprostanes on cholinergic neurotransmission in guinea-pig trachea and identified the receptor(s) involved. As isoprostanes are isomeric with prostaglandins, PGE(2) and sulprostone (a selective EP(3)-receptor agonist) were examined in parallel. 2. 8-Iso-PGE(1), 8-iso-PGE(2) (0.1 nm-1 microM), sulprostone (1 nm-1 microM) and PGE(2) (1 microM) suppressed EFS-evoked [(3)H]ACh release from guinea-pig trachea in a concentration-dependent manner, producing 39.5, 53.9, 61.2 and 59.9% inhibition, respectively, at 1 microM. It should be noted that an established maximum effective concentration was not determined. 3. Neither SQ 29,548 (1 microm; a TP-receptor antagonist) nor AH 6809 (10 microM; an EP(1)-/EP(2)-/DP-receptor antagonist) reversed the inhibitory effect of these compounds. 4. L-798,106, a novel and highly selective EP(3)-receptor antagonist, produced a parallel shift to the right of the concentration-response curves that described the inhibitory action of sulprostone on EFS-evoked contractile responses in guinea-pig vas deferens (an established EP(3)-receptor-expressing tissue), from which a mean pA(2) of 7.48 was derived. On guinea-pig trachea, L-798,106 also antagonised sulprostone-induced inhibition of EFS-induced twitch responses, with similar potency (mean pA(2)=7.82). 5. The inhibitory effects of 8-iso-PGE(1), 8-iso-PGE(2), sulprostone and PGE(2) on EFS-induced [(3)H]ACh release was blocked by L-798,106 at a concentration (10 microM) that binds only weakly to human recombinant EP(1)-, EP(2)- and EP(4)-receptor subtypes expressed in HEK 293 cells. 6. These data suggest that E-ring 8-isoprostanes, PGE(2) and sulprostone inhibit EFS-evoked [(3)H]ACh release from cholinergic nerves innervating guinea-pig trachea, by interacting with prejunctional prostanoid receptors of the EP(3)-subtype.

Isoprostane-mediated secretion from human airway epithelial cells

Isoprostanes are liberated when reactive oxygen species (ROS) mediate the peroxidation of arachidonic acid or other polyunsaturated fatty acids. Because exposure to ROS is associated with tissue damage in the lung, we examined whether exposure to isoprostanes elicited a response in airway epithelial cells, potentially implicating isoprostane production in the epithelial response to oxidant stress. Application of the isoprostane 8-iso-prostaglandin E2 (8-iso-PGE2) produced an increase in transepithelial anion secretion across monolayers of the human airway epithelial cell line Calu-3, measured as an increase in short circuit current (Isc). This increase in Isc was greater when 8-iso-PGE2 was applied to the basolateral rather than the apical face of the Calu-3 monolayers and was almost entirely abolished by the addition of diphenylamine-2-carboxylate, implicating the cystic fibrosis transmembrane conductance regulator Cl- channel in the response. Experiments with electrically isolated apical and basolateral membrane preparations revealed that 8-iso-PGE2 stimulated both apical Cl- and basolateral K+ conductances. Using reverse transcription-polymerase chain reaction, we found that Calu-3 cells express the TPalpha, but not the TPbeta, isoform of the receptor, and that these cells secrete in response to the thromboxane A2 (TP) receptor agonist 9,11-dideoxy-9alpha,11alpha-methanoepoxy-prostaglandin F2alpha (U-46619). However, although part of the response seems to mediated via TP receptors, there are significant non-TP receptor-mediated effects on both the apical and basolateral membranes of Calu-3 cells. This is the first report of an isoprostane eliciting an effect in airway epithelial cells and suggests a potential role for this class of molecules in pulmonary host defense.

The isoprostanes: their role as an index of oxidant stress status in human pulmonary disease

The isoprostanes are a unique series of prostaglandin-like compounds formed in vivo from the free radical-initiated peroxidation of arachidonic acid independent of the cyclooxygenase enzyme. This article summarizes selected aspects regarding our current knowledge of these compounds and what are considered avenues for future research. Novel aspects related to the biochemistry of isoprostane formation are discussed first, followed by a summary of methods by which these compounds are analyzed. A considerable portion of this article deals with the utility of measuring isoprostanes as markers of oxidant injury in vitro and in vivo, particularly in pulmonary diseases. Studies performed over the past decade have shown that these compounds are extremely accurate measures of lipid peroxidation in animals and humans and have illuminated the role of oxidant injury in a number of human diseases, including those related to the lung.

Monocyte and neutrophil adhesion molecule expression during acute hyperglycemia and after antioxidant treatment in type 2 diabetes and control patients

OBJECTIVE

We hypothesized that acute hyperglycemia (an independent cardiovascular risk factor) increases the expression of proatherogenic leukocyte adhesion molecule in type 2 diabetes and controls and that the expression of these adhesion molecules would be antioxidant sensitive.

METHODS AND RESULTS

Twenty-three type 2 diabetes patients and 13 control patients underwent two oral glucose tolerance tests 14 days apart and took placebo or 800 IU daily of oral alpha tocopherol between tests. Monocyte and neutrophil expression of adhesion molecules Mac-1, LFA-1 and 3, ICAM-1, and VLA-4 were measured at 0, 120, and 240 minutes by using laser flow cytometry. Baseline adhesion molecule expression did not differ between groups, but there was a rapid, highly significant increase (P<0.0001) in the intensity of monocyte Mac-1 expression after a glucose load in both groups. Alpha-tocopherol supplementation reduced only Mac-1 expression in the diabetes group (P=0.03).

CONCLUSIONS

Acute glycemic excursions of any degree cause highly significant, rapid increases in monocyte Mac-1 expression in type 2 diabetes patients and controls. Mac-1 mediates leukocyte vascular infiltration and is prothrombotic. These data suggest a mechanism for the link between glycemic excursions and increased vascular event rates.

Alteration of a macrophages inflammatory protein-related protein-2 (MRP-2) response by high fat and cholesterol diet in mice

Macrophage inflammatory protein-related protein-2 (MRP-2) is a new member of the CC chemokine family that is recently identified in murine macrophages. MRP-2 is involved in leukocyte trafficking and activation, which can be implicated in inflammatory diseases including atherosclerosis. Little is known about the involvement of this novel chemokine MRP-2 in the pathogenesis of atherosclerosis. To explore the possible association of the MRP-2 with atherosclerosis, we investigated the effects of atherogenic diet on MRP-2 expression in mice. Male C57BL/6 mice were fed a high fat and cholesterol diet (20% fat and 1.5% cholesterol) or a control diet based on AIN-76 for 5, 10, or 14 weeks. The levels of total cholesterol, LDL cholesterol, and F2-isoprostanes in plasma were measured using appropriate enzymatic assays. Tumor necrosis factor alpha (TNF alpha) and MCP-1 release by peritoneal macrophages was determined by ELISA. The mRNA expression level of the MRP-2 was measured by RT-PCR. The levels of total cholesterol, LDL-cholesterol, and 8-iso-prostaglandin F2 alpha in plasma, well-known indexes of atherosclerosis, were significantly increased in the high fat and cholesterol diet group compared to those in the control. A significant increase in the TNF alpha and MCP-1 production by macrophages was also observed in the group fed high fat and cholesterol diet. The mRNA expression of MRP-2 was upregulated by oxLDL treatment in vitro and feeding a high fat and cholesterol diet in vivo at the late stage of atherosclerosis. These results suggest that MRP-2 may be an important contributing factor in the development of atherosclerosis.

Nonenzymatic derived lipid peroxide, 8-iso-PGF2 alpha, participates in the pathogenesis of delayed cerebral vasospasm in a canine SAH model

We studied whether 8-iso-PGF2alpha, nonenzymatic arachidonyl peroxide, participated in the pathogenesis of delayed vasospasm using a canine subarachnoid hemorrhage (SAH) model. Fourteen adult mongrel dogs were divided into two groups, two-hemorrhage SAH group (n = 8) and control group (n = 6). The contents of 8-iso-PGF2alpha in CSF, the basilar artery segment, and subarachnoid clot were measured by enzyme immunoassay kit. The CSF 8-iso-PGF2alpha content on Day 7 in the SAH group was 67.9+/-29.9 pg ml(-1) (n = 8), which was significantly higher than 27.1+/-13.8 (n = 8) on Day 0 in the SAH group, and 33.2+/-14.4 pg ml(-1) (n = 5) on Day 7 in the control group. The 8-iso-PGF2alpha content in the basilar artery segment with spasm on Day 7 in the SAH group was 13.5+/-1.9 pg mg(-1) wet weight (n = 8), significantly higher than 8.7+/-1.9 (n = 6) in the control group. The 8-iso-PGF2alpha content in subarachnoid clot was 1.7+/-1.4 ng g(-1) wet weight (n = 8). Significant elevation of the 8-iso-PGF2alpha contents in the CSF and the basilar artery segment occurred on Day 7 in the SAH group. The subarachnoid clot enclosed the basilar artery on Day 7, contained a considerable amount of 8-iso-PGF2alpha. These results suggested that 8-iso-PGF2alpha could play a crucial role in the pathogenesis of the delayed cerebral vasospasm.

Isoprostanes: an overview and putative roles in pulmonary pathophysiology

Isoprostanes are produced during peroxidation of membrane lipids by free radicals and reactive oxygen species. Initially, they were recognized as being valuable markers of oxidative stress, and in the past 10 years, dozens of disease states and experimental conditions with diverse etiologies have been shown to be associated with marked increases in urinary, plasma, and tissue levels of isoprostanes. However, they are not just mere markers; they evoke important biological responses on virtually every cell type found within the lung, and these responses exhibit compound-, tissue-, and species-related variations. In fact, the isoprostanes may mediate many of the features of the disease states for which they are used as indicators. In this review, I describe the chemistry, metabolism, and pharmacology of isoprostanes, with a particular emphasis on pulmonary cell types, and the possible roles of isoprostanes in pulmonary pathophysiology.

NK-1 antagonist reduces colonic inflammation and oxidative stress in dextran sulfate-induced colitis in rats

Although substance P (SP) has been implicated as a mediator of neurogenic inflammation in the small intestine, little information is available regarding the role of SP in the pathogenesis of chronic ulcerative colitis. In this study, our aim was to investigate whether the intraperitoneal administration of a nonpeptide neurokinin-1 (NK-1) antagonist, CP-96345, which antagonizes the binding of SP to its NK-1 receptor, results in the attenuation of colonic inflammation induced in rats by 5% dextran sodium sulfate (DSS) in drinking water for 10 days compared with an inactive enantiomer, CP-96344. Disease activity was assessed daily for 10 days, after which colonic tissue damage was scored and myeloperoxidase activity and colon and urinary 8-isoprostanes were measured. Animals receiving DSS exhibited marked physical signs of colitis by day 5 compared with controls. Chronic administration of the NK-1 antagonist significantly reduced the disease activity index, mucosal myeloperoxidase activity, colonic tissue damage score, and mucosal and urinary levels of 8-isoprostanes compared with inactive enantiomer- or vehicle-injected (saline) animals receiving DSS alone. These data indicate that the administration of an NK-1 antagonist can attenuate colonic inflammation and oxidative stress and suggest a novel therapeutic approach in the treatment of chronic ulcerative colitis.

C-nociceptor sensitization by isoprostanes is cyclooxygenase dependent

Isoprostane E(2) (8-iso-PGE) and F(2alpha) (8-iso-PGF) sensitize nociceptors and capsaicin-sensitive DRG neurons. In this study we investigated the cyclooxygenase-dependence of isoprostane-induced C-nociceptor sensitization. Systemic pretreatment of rats with ketorolac (1 and 10 mg/kg) abolished 8-iso-PGF sensitization and reduced the effects of 8-iso-PGE. Ibuprofen (30 mg/kg) blocked all sensitizing effects. These data suggest that some algesic properties of isoprostanes are mediated via prostanoid synthesis.