Prostanoid Levels Research Articles

A high seizure burden increases several prostaglandin species in the hippocampus of a Scn1a+/- mouse model of Dravet syndrome

Dravet syndrome is an intractable epilepsy with a high seizure burden that is resistant to current anti-seizure medications. There is evidence that neuroinflammation plays a role in epilepsy and seizures, however few studies have specifically examined neuroinflammation in Dravet syndrome under conditions of a higher seizure burden. Here we used an established genetic mouse model of Dravet syndrome (Scn1a+/- mice), to examine whether a higher seizure burden impacts the number and morphology of microglia in the hippocampus. Moreover, we examined whether a high seizure burden influences classical inflammatory mediators in this brain region. Scn1a+/- mice with a high seizure burden induced by thermal priming displayed a localised reduction in microglial cell density in the granule cell layer and subgranular zone of the dentate gyrus, regions important to postnatal neurogenesis. However, microglial cell number and morphology remained unchanged in other hippocampal subfields. The high seizure burden in Scn1a+/- mice did not affect hippocampal mRNA expression of classical inflammatory mediators such as interleukin 1β and tumour necrosis factor α, but increased cyclooxygenase 2 (COX-2) expression. We then quantified hippocampal levels of prostanoids that arise from COX-2 mediated metabolism of fatty acids and found that Scn1a+/- mice with a high seizure burden displayed increased hippocampal concentrations of numerous prostaglandins, notably PGF2α, PGE2, PGD2, and 6-K-PGF1A, compared to Scn1a+/- mice with a low seizure burden. In conclusion, a high seizure burden increased hippocampal concentrations of various prostaglandin mediators in a mouse model of Dravet syndrome. Future studies could interrogate the prostaglandin pathways to further better understand their role in the pathophysiology of Dravet syndrome.

Urinary prostanoids are elevated by anti-TNF and anti-IL6 receptor disease-modifying antirheumatic drugs but are not predictive of response to treatment in early rheumatoid arthritis

BackgroundDisease-modifying antirheumatic drugs (DMARDs) are widely used for treating rheumatoid arthritis (RA). However, there are no established biomarkers to predict a patient’s response to these therapies. Prostanoids, encompassing prostaglandins, prostacyclins, and thromboxanes, are potent lipid mediators implicated in RA progression. Nevertheless, the influence of DMARDs on prostanoid biosynthesis in RA patients remains poorly understood. This study aims to assess the impact of various DMARDs on urinary prostanoids levels and to explore whether urinary prostanoid profiles correlate with disease activity or response to therapy.MethodsThis study included 152 Swedish female patients with early RA, all rheumatoid factor (RF) positive, enrolled in the NORD-STAR trial (registration number: NCT01491815). Participants were randomized into four therapeutic regimes: methotrexate (MTX) combined with (i) prednisolone (arm ACT), (ii) TNF-α blocker certolizumab pegol (arm CZP), (iii) CTLA-4Ig abatacept (arm ABA), or (iv) IL-6R blocker tocilizumab (arm TCZ). Urine samples, collected before start of treatment and at 24 weeks post-treatment, were analyzed for tetranor-prostaglandin E metabolite (tPGEM), tetranor-prostaglandin D metabolite (tPGDM), 2,3-dinor thromboxane B2 (TXBM), 2,3-dinor-6-keto prostaglandin F1a (PGIM), leukotriene E4 (LTE4) and 12-hydroxyeicosatetraenoic acid (12-HETE) using liquid chromatography–mass spectrometry (LC–MS). Generalized estimating equation (GEE) models were used to analyze the change in urinary eicosanoids and their correlations to clinical outcomes.ResultsPatients receiving MTX combined with CZP or TCZ exhibited significant elevations in urinary tPGEM and TXBM levels after 24 weeks of treatment. Other eicosanoids did not show significant alterations in response to any treatment. Baseline urinary eicosanoid levels did not correlate with baseline clinical disease activity index (CDAI) levels, nor with changes in CDAI from baseline to week 24. Their levels were also similar between patients who achieved CDAI remission and those with active disease at week 24.ConclusionsTreatment with anti-TNF or anti-IL6R agents in early RA patients leads to an increased systemic production of proinflammatory and prothrombotic prostanoids. However, urinary eicosanoid levels do not appear to be predictive of the response to DMARDs therapy.

Thromboxane A2-TP axis promotes adipose tissue macrophages M1 polarization leading to insulin resistance in obesity

Aberrant arachidonic acid metabolism has been implicated in multiple pathophysiological conditions, and the downstream prostanoids levels are associated with adipocyte dysfunction in obesity. However, the role of thromboxane A2 (TXA2) in obesity remains unclear. We observed that TXA2, through its receptor TP, is a candidate mediator in obesity and metabolic disorders. Obese mice with upregulated TXA2 biosynthesis (TBXAS1) and TXA2 receptor (TP) expression in caused insulin resistance and macrophage M1 polarization in white adipose tissue (WAT), which can be prevented by treatment with aspirin. Mechanistically, the activation of TXA2-TP signaling axis leads to accumulation of protein kinase Cɛ (PKCɛ), thereby enhancing free fat acid (FFA) induced Toll-like receptor4 (TLR4) proinflammatory macrophage activation and the tumor necrosis factor–a (TNF-a) production in adipose tissues. Importantly, TP knockout mice reduced the accumulation of proinflammatory macrophages and adipocyte hypertrophy in WAT. Thus, our findings demonstrate that TXA2-TP axis plays a crucial role in obesity-induced adipose macrophage dysfunction, and rational targeting TXA2 pathway may improve obesity and its associated metabolic disorders in future. In this work, we establish previously unknown role of TXA2-TP axis in WAT. These findings might provide new insight into the molecular pathogenesis of insulin resistance, and indicate rational targeting TXA2 pathway to improve obesity and its associated metabolic disorders in future.

Inhibition of P2X7 receptors by Lu AF27139 diminishes colonic hypersensitivity and CNS prostanoid levels in a rat model of visceral pain.

Visceral pain is a prominent feature of various gastrointestinal diseases. The P2X7 receptor is expressed by multiple cell types including dorsal root ganglion satellite glial cells, macrophages, and spinal microglia, all of which have been implicated in nociceptive sensitization. We have used the selective and CNS penetrant P2X7 receptor antagonist Lu AF27139 to explore this receptor's role in distinct rat models of inflammatory and visceral hypersensitivity. Rats injected with CFA in the hindpaw displayed a marked reduction in hindpaw mechanical threshold, which was dose-dependently reversed by Lu AF27139 (3-30mg/kg, p.o.). In rats injected with TNBS in the proximal colon, the colorectal distension threshold measured distally was significantly lower than sham treated rats at 7days post-injection (P < 0.001), indicative of a marked central sensitization. Colonic hypersensitivity was also reversed by Lu AF27139 (10-100mg/kg) and by the κ-opioid receptor agonist U-50,488H (3mg/kg, s.c.). Moreover, both Lu AF27139 and U-50,488H prevented a TNBS-induced increase in spinal and brain levels of PGE2 and LTB4, as well as an increase in brain levels of PGF2α and TXB2. Lu AF27139 was well tolerated as revealed by a lack of significant effect on rotarod motor function and coordination at all doses tested up to 300mg/kg. Thus, P2X7 receptor antagonism is efficacious in a rat model of visceral pain, via a mechanism which potentially involves attenuation of microglial function within spinal and/or supraspinal pain circuits, albeit a peripheral site of action cannot be excluded.

Differential effects of cyclo-oxygenase 1 and 2 inhibition on angiogenesis inhibitor-induced hypertension and kidney damage.

Vascular endothelial growth factor antagonism with angiogenesis inhibitors in cancer patients induces a ‘preeclampsia-like’ syndrome including hypertension, proteinuria and elevated endothelin (ET)-1. Cyclo-oxygenase (COX) inhibition with aspirin is known to prevent the onset of preeclampsia in high-risk patients. In the present study, we hypothesised that treatment with aspirin would prevent the development of angiogenesis inhibitor-induced hypertension and kidney damage. Our aims were to compare the effects of low-dose (COX-1 inhibition) and high-dose (dual COX-1 and COX-2 inhibition) aspirin on blood pressure, vascular function, oxidative stress, ET-1 and prostanoid levels and kidney damage during angiogenesis-inhibitor therapy in rodents. To this end, Wistar Kyoto rats were treated with vehicle, angiogenesis inhibitor (sunitinib) alone or in combination with low- or high-dose aspirin for 8 days (n=5–7/group). Our results demonstrated that prostacyclin (PGI2) and ET-1 were increased during angiogenesis-inhibitor therapy, while thromboxane (TXA2) was unchanged. Both low- and high-dose aspirin blunted angiogenesis inhibitor-induced hypertension and vascular superoxide production to a similar extent, whereas only high-dose aspirin prevented albuminuria. While circulating TXA2 and prostaglandin F2α levels were reduced by both low- and high-dose aspirin, circulating and urinary levels PGI2 were only reduced by high-dose aspirin. Lastly, treatment with aspirin did not significantly affect ET-1 or vascular function. Collectively our findings suggest that prostanoids contribute to the development of angiogenesis inhibitor-induced hypertension and renal damage and that targeting the prostanoid pathway could be an effective strategy to mitigate the unwanted cardiovascular and renal toxicities associated with angiogenesis inhibitors.

A vitamin E long-chain metabolite and the inspired drug candidate α-amplexichromanol relieve asthma features in an experimental model of allergen sensitization

Benefits for vitamin E intake in diseases with inflammatory components have been described and related in part, to endogenously formed metabolites (long-chain metabolites, LCM). Here, we have evaluated the role of LCM in relieving asthma features. To this aim, the endogenous vitamin E metabolite α-13′-carboxychromanol (α-T-13′-COOH) that acts as potent 5-lipoxygenase inhibitor has been administered either intraperitoneally or by oral gavage to BALB/c mice sensitized by subcutaneous injection of ovalbumin (OVA). We also have taken advantage of the metabolically stable α-T-13′-COOH derivative α-amplexichromanol (α-AC). Intraperitoneal treatment with α-T-13'-COOH reduced OVA-induced airway hyperreactivity (AHR) as well as peri-bronchial inflammatory cell infiltration. α-AC was more efficacious than α-T-13'-COOH, as demonstrated by better control of AHR and in reducing subepithelial. Both compounds exerted their protective function by reducing pulmonary leukotriene C4 levels. Beneficial effects of α-AC were coupled to inhibition of the sensitization process, as indicated by a reduction of IgE plasma levels, lung mast cell infiltration and Th2 immune response. Metabololipidomics analysis revealed that α-AC raises the pulmonary levels of prostanoids, their degradation products, and 12/15-lipoxygenase metabolites. Following oral administration, the pharmacodynamically different profile in α-T-13′-COOH and α-AC was abrogated as demonstrated by a similar and improved efficacy in controlling asthma features as well as by metabololipidomics analysis. In conclusion, this study highlights a role for LCM and of vitamin E derivatives as pharmacologically active compounds that ameliorate asthmatic features and defines an important role for endogenous vitamin E metabolites in regulating immune response underlying the sensitization process.

Glucose infusion suppresses acute restraint stress-induced peripheral and central sympathetic responses in rats.

Acute restraint stress (RS) induces sympathetic activation such as elevating plasma catecholamines, resulting in increase in blood glucose. We aimed to investigate whether glucose infusion affects the RS-induced sympathetic responses. Plasma catecholamines were measured by high-performance liquid chromatography with electrochemical detection. Blood glucose levels were measured with a glucometer and a glucose assay kit. Cardiac parameters were measured by echocardiographic and hemodynamic analysis. Prostanoid levels in the paraventricular nucleus of hypothalamus (PVN) microdialysates were measured by liquid chromatography-ion trap tandem mass spectrometry analysis. RS significantly increased plasma noradrenaline and adrenaline. Intravenous infusion of a 5% glucose solution significantly attenuated the RS-induced elevation of plasma adrenaline but did not alter the plasma noradrenaline. Glucose administration during RS suppressed the progression of cardiac impairment by attenuating the decline rates in left ventricular diastolic, end-diastolic volume, stroke volume, fractional shortening, and ejection fraction. Both Intravenous and intracerebroventricular infusion of glucose solution significantly attenuated the RS-induced elevation of thromboxane B2 (TxB2) (a metabolite of TxA2) levels in the PVN but did not alter prostaglandin E2 levels in the PVN. Our results demonstrate that glucose infusion suppresses RS-induced elevation of plasma adrenaline and left ventricular dysfunction. In the brain, glucose infusion suppresses RS-induced production of TxA2 in the PVN.

Diesel exhaust particles alter cAMP dynamics in human bronchial epithelial cells

Diesel exhaust particles (DEP) are one of the main causes of air pollution and are associated with lung disorders. DEP exposure may promote several pathological processes, including epithelial‐to‐mesenchymal transition (EMT), inflammation and oxidative stress, which contribute to a decline in lung function. Cyclic AMP (cAMP) has been reported to alleviate lung dysfunction. The impact of DEP on cAMP signaling is largely unknown. Human bronchial epithelial (BEAS‐2B) cells were exposed to different concentrations (≤ 300 µg/ml) for up to 72 h. Markers of oxidative stress, inflammation, EMT, components of mitochondrial bioenergetics and cAMP signaling were evaluated. DEP increased gene expression of Nrf1, thioredoxin, HO‐1 and SOD‐2 (oxidative stress markers), and interleukin (IL)‐6 and IL‐8 (inflammatory markers), as well as the EMT marker transforming growth factor‐β1 (both mRNA and protein). Epithelial cell markers (E‐cadherin, ZO‐1) were reduced by DEP, whereas mesenchymal markers (β‐catenin, collagen‐1) were increased. DEP reduced both basal and ATP‐linked respiration as well as the glycolytic capacity of mitochondria. Concomitantly, DEP profoundly altered mitochondrial morphology and increased the gene expression of A‐kinase anchoring protein (AKAP) 1 (a known mitochondrial scaffold protein). Furthermore, DEP significantly affected Epac1 mRNA levels and appeared to increase Epac1 protein, but did not alter the expression of phospho‐PKA substrates. Interestingly, DEP increased gene expression levels of several AC family members (AC3, AC6 and AC7), the β2‐adrenoceptor (β2‐AR) and prostanoid E receptor subtype 4 (EP4). Importantly, real‐time measurements of cAMP demonstrated that DEP strongly reduced cAMP induced by forskolin (AC activator), fenoterol (β2‐AR agonist) and a stable EP4 agonist, implicating that DEP might limit the therapeutic effects of β2‐AR agonists used to treat lung disorders. Our findings suggest that DEP promotes oxidative stress, inflammation, and EMT. These profound alterations in cellular behavior were accompanied by changes in mitochondrial dysfunction and real‐time cAMP dynamics, which may contribute to lung dysfunction induced by air pollution exposure.

Диклофенак устраняет влияние фактора некроза опухоли на систему кровообращения анестезированной крысы

Functioning of visceral systems in hypercytokinemia induced, inter alia, by an increase in the systemic level of bacterial lipopolysaccharides (LPS) is an important item on the research agenda in physiology. Hypercytokinemia disrupts effective functioning of visceral systems, in particular, the circulatory system. The aim of the study was to test the hypothesis that an increase in the systemic level of the pro-inflammatory cytokine tumor necrosis factor (TNF-α) changes circulatory parameters due to an increased synthesis of the inducible isoform of the cyclooxygenase enzyme (COX-2). In experiments on male Wistar rats (n = 14) anesthetized with urethane (1.6 g/kg), we studied the effects of intravenous administration of TNF-α on mean arterial pressure (MAP) and heart rate (HR) as well as the influence of the COX blocker diclofenac (DC) on the effects in question. It was found that 40 minutes after the administration of TNF-α (45 μg/kg), the mean BP and HR in the anesthetised rat rise significantly, while the preliminary administration of DC (2.5 μg/kg) prevents the development of these effects. Thus, the proposed hypothesis was experimentally confirmed. It is assumed that the observed effects of TNF-α are induced by the influence of increased levels of prostanoids on the structures of the central nervous system regulating the activity of visceral systems.

Analysis of Sex-Specific Prostanoid Production Using a Mouse Model of Selective Cyclooxygenase-2 Inhibition.

Prostanoids are a family of lipid mediators formed from arachidonic acid by cyclooxygenase enzymes and serve as biomarkers of vascular function. Prostanoid production may be different in males and females indicating that different therapeutic approaches may be required during disease. We examined sex-dependent differences in COX-related metabolites in genetically modified mice that produce a cyclooxygenase-2 (COX2) enzyme containing a tyrosine 385 to phenylalanine (Y385F) mutation. This mutation renders the COX2 enzyme unable to form a key intermediate radical required for complete arachidonic acid metabolism and provides a model of selective COX2 inhibition. Mice heterozygous for the Y385F mutation in COX2 were mated to produce cohorts of wild-type, heterozygous, and COX2 mutant mice. We investigated whether the genotype distribution followed Mendelian genetics and studied whether sex-specific differences could be found in certain prostanoid levels measured in peritoneal macrophages and in urinary samples. The inheritance of the COX2 mutation displayed a significant deviation with respect to Mendel's laws of genetics, with a lower-than-expected progeny of weaned COX2 mutant pups. In macrophages, prostaglandin E2 (PGE2) production following lipopolysaccharide (LPS) and interferon gamma (IFNγ) stimulation was COX2-dependent in both males and females, and data indicated that crosstalk between the nitric oxide (NO) and COX2 pathways may be sex specific. We observed significant differences in urinary PGE2 production by male and female COX2 mutant mice, with the loss of COX2 activity in male mice decreasing their ability to produce urinary PGE2. Finally, female mice across all 3 genotypes produced similar levels of urinary thromboxane (measured as 11-dehydro TxB2) at significantly higher levels than males, indicating a sex-related difference that is likely COX1-derived. Our findings clearly demonstrate that sex-related differences in COX-derived metabolites can be observed, and that other pathways (such as the NO pathway) are affected.

Purinergic signaling is enhanced in the absence of UT-A1 and UT-A3.

ATP is an important paracrine regulator of renal tubular water and urea transport. The activity of P2Y2, the predominant P2Y receptor of the medullary collecting duct, is mediated by ATP, and modulates urinary concentration. To investigate the role of purinergic signaling in the absence of urea transport in the collecting duct, we studied wild‐type (WT) and UT‐A1/A3 null (UT‐A1/A3 KO) mice in metabolic cages to monitor urine output, and collected tissue samples for analysis. We confirmed that UT‐A1/A3 KO mice are polyuric, and concurrently observed lower levels of urinary cAMP as compared to WT, despite elevated serum vasopressin (AVP) levels. Because P2Y2 inhibits AVP‐stimulated transport by dampening cAMP synthesis, we suspected that, similar to other models of AVP‐resistant polyuria, purinergic signaling is increased in UT‐A1/A3 KO mice. In fact, we observed that both urinary ATP and purinergic‐mediated prostanoid (PGE2) levels were elevated. Collectively, our data suggest that the reduction of medullary osmolality due to the lack of UT‐A1 and UT‐A3 induces an AVP‐resistant polyuria that is possibly exacerbated by, or at least correlated with, enhanced purinergic signaling.

Impaired UTP-induced relaxation in the carotid arteries of spontaneously hypertensive rats.

Uridine 5'-triphosphate (UTP) has an important role as an extracellular signaling molecule that regulates inflammation, angiogenesis, and vascular tone. While chronic hypertension has been shown to promote alterations in arterial vascular tone regulation, carotid artery responses to UTP under hypertensive conditions have remained unclear. The present study investigated carotid artery responses to UTP in spontaneously hypertensive rats (SHR) and control Wistar Kyoto rats (WKY). Accordingly, our results found that although UTP promotes concentration-dependent relaxation in isolated carotid artery segments from both SHR and WKY after pretreatment with phenylephrine, SHR exhibited significantly lower arterial relaxation responses compared with WKY. Moreover, UTP-induced relaxation was substantially reduced by endothelial denudation and by the nitric oxide (NO) synthase inhibitor NG-nitro-L-arginine in both SHR and WKY. The difference in UTP-induced relaxation between both groups was abolished by the selective P2Y2 receptor antagonist AR-C118925XX and the cyclooxygenase (COX) inhibitor indomethacin but not by the thromboxane-prostanoid receptor antagonist SQ29548. Furthermore, we detected the release of PGE2, PGF2α, and PGI2 in the carotid arteries of SHR and WKY, both at baseline and in response to UTP. UTP administration also increased TXA2 levels in WKY but not SHR. Overall, our results suggest that UTP-induced relaxation in carotid arteries is impaired in SHR perhaps due to impaired P2Y2 receptor signaling, reductions in endothelial NO, and increases in the levels of COX-derived vasoconstrictor prostanoids.

Thromboxane A2 in the paraventricular hypothalamic nucleus mediates glucoprivation-induced adrenomedullary outflow

Glucoprivation stimulates a rapid sympathetic response to release and/or secrete catecholamines into the bloodstream. However, the central regulatory mechanisms involving adrenoceptors and prostanoids production in the paraventricular hypothalamic nucleus (PVN) that are responsible for the glucoprivation-induced elevation of plasma catecholamines are still unresolved. In this study, we aimed to clarify whether glucoprivation-induced activation of noradrenergic neurons projecting to the PVN can induce α- and/or β-adrenergic receptor activation and prostanoids production in the PVN to elevate plasma catecholamine levels. We examined the effects of α- and β-adrenergic receptor antagonists, a cyclooxygenase inhibitor, a thromboxane A synthase inhibitor, and a PGE2 subtype EP3 receptor antagonist on intravenously administered 2-deoxy-D-glucose (2-DG)-induced elevation of noradrenaline in the PVN and plasma levels of catecholamine in freely moving rats. In addition, we examined whether intravenously administered 2-DG can increase prostanoids levels in the PVN microdialysates. Intracerebroventricular (i.c.v.) pretreatment with phentolamine (a non-selective α-adrenergic receptor antagonist) suppressed the 2-DG-induced increase in the plasma level of adrenaline, whereas i.c.v. pretreatment with propranolol (a non-selective β-adrenergic receptor antagonist) suppressed the 2-DG-induced elevation of the plasma level of noradrenaline. I.c.v. pretreatment with indomethacin (a cyclooxygenase inhibitor) and furegrelate (a thromboxane synthase inhibitor) attenuated the 2-DG-induced elevations of both noradrenaline and adrenaline levels. Furthermore, 2-DG administration elevated the thromboxane B2 level, a metabolite of thromboxane A2 in PVN microdialysates. Our results suggest that glucoprivation-induced activation of α- and β-adrenergic receptor in the brain including the PVN and then thromboxane A2 production in the PVN, which are essential for the 2-DG-induced elevations of both plasma adrenaline and noradrenaline levels.

Blood-Brain Barrier Is the Major Site for a Rapid and Dramatic Prostanoid Increase upon Brain Global Ischemia.

We and others have demonstrated a rapid and dramatic increase in brain prostanoids upon decapitation-induced brain global ischemia and injury. However, the mechanism for this induction, including the cell types involved, are unknown. In the present study, we have validated and applied a pharmacological approach to inhibit prostanoid synthesis in the blood-brain barrier including endothelial cells. Our results indicate that a nonspecific cyclooxygenase (COX) inhibitor, ketorolac, does not pass the blood-brain barrier and does not enter red blood cells but penetrates endothelial cells. Ketorolac treatment did not affect basal prostanoid levels but completely prevented prostanoid induction upon global ischemia. These data indicate that basal prostanoids are synthesized in brain parenchyma cells, while inducible prostanoids are synthesized in the blood-brain barrier, most likely in endothelial cells. However, future studies with cell and COX isoform-specific gene ablation are needed to further validate this conclusion. These findings identify endothelial cells as a possible target for the development of pharmacological approaches to selectively attenuate inducible prostanoid pools without affecting basal levels under brain ischemia, trauma, surgery, and other related conditions.

Urinary prostaglandin D2 and E2 metabolites associate with abdominal obesity, glucose metabolism, and triglycerides in obese subjects

Obesity is associated with low-grade chronic inflammation, which contributes to the development of the metabolic syndrome and its associated complications, such as insulin resistance and type-2 diabetes. Limited data from animal and human studies support local generation of pro-inflammatory prostanoid lipid mediators in white adipose tissue. However, the link between systemic prostanoid levels and parameters characterizing the metabolic syndrome is missing in human obesity. Therefore, we performed a targeted lipidomic analysis using urine samples from obese human subjects (n = 45) and show for the first time in humans that urinary prostanoid levels correlate with metabolic parameters that indicate a dysregulated glucose and triglyceride metabolism. We identified tetranor-PGDM and tetranor-PGEM as the two major urinary prostanoid metabolites in obese subjects with levels of 247 ± 31 and 23.3 ± 4.0 pmol/mg creatinine, respectively. Tetranor-PGDM was significantly associated with serum triglycerides, while tetranor-PGEM was associated with abdominal obesity as defined by an increased waist-to-hip ratio (WHR), with glycated hemoglobin (HbA1c), and with impaired oral glucose tolerance. These results confirm the previously established notion of low-grade chronic inflammation in obesity and further identify an association of the prostanoid pathway with obesity-associated dyslipidemia, abdominal obesity, and insulin resistance.

Camelina sativa Oil, Fatty Fish, and Lean Fish Do Not Markedly Affect Urinary Prostanoids in Subjects with Impaired Glucose Metabolism.

Dietary fatty acids are suggested to affect oxidative stress; however, results from interventions have been inconclusive. The aim was to examine if fatty fish, lean fish, and Camelina sativa oil (CSO) affect the urinary prostanoid levels in subjects with impaired glucose metabolism. Altogether 79 participants aged 43-72 years completed a randomized controlled study lasting 12 weeks. There were four parallel groups, fatty fish, lean fish (four fish meals/week in both), CSO providing 10 g/day alpha-linolenic acid (ALA), and control diet with limited fish and ALA containing oil consumption. Urinary prostanoids (prostaglandin F2α , 5-F2t -isoprostanes and 15-F2t -isoprostane metabolites, isofuran, 8-F3t -isoprostanes, and 4-(RS)-4-F4t -neuroprostane) of 72 participants (age: mean (±SD) 58.9 ± 6.5 years; body mass index: 29.3 ± 2.5 kg/m2 ) collected over 12-h were measured using liquid chromatography tandem-mass spectrometry. Plasma phospholipid fatty acids were determined using gas chromatography. Our study showed that the proportion of ALA in plasma phospholipids increased in the CSO group (overall difference among the groups p-value <0.001). In the fatty fish group, proportions of eicosapentaenoic and docosahexaenoic acids increased (overall p-value <0.001 for both). Prostaglandin F2α was higher in the CSO group than in the control group (p < 0.05), however, there were no other significant changes in urinary excretion of other prostanoids among the study groups. At baseline, arachidonic acid in plasma phospholipids was positively (r = 0.247, p < 0.05) and ALA negatively (r = -0.326, p < 0.05) associated with urinary total isoprostanes. In conclusion, CSO, fatty fish, and lean fish consumption do not cause major changes in oxidative stress markers in subjects with impaired glucose tolerance.

Prostaglandin E2 decrease in induced sputum of hypersensitive asthmatics during oral challenge with aspirin.

A special regulatory role for prostaglandin E2 (PGE2 ) has been postulated in nonsteroidal anti-inflammatory drug (NSAID)-exacerbated respiratory disease (NERD). To investigate the effect of systemic aspirin (acetylsalicylic acid) administration on airway PGE2 biosynthesis in induced sputum supernatant (ISS) among subjects with NERD or aspirin-tolerant asthma with chronic rhinosinusitis with nasal polyposis (ATA-CRSwNP), as well as healthy controls (HC). Induced sputum (IS) was collected from patients with NERD (n=26), ATA-CRSwNP (n=17), and HC (n=21) at baseline and after aspirin challenge. Sputum differential cell count and IS supernatant (ISS) levels of prostanoids, PGE2 , 8-iso-PGE2 , tetranor-PGE-M, 8-iso-PGF2 α, and leukotriene C4 , D4 , and E4 , were determined using mass spectrometry. Urinary excretion of LTE4 was measured by ELISA. NERD subjects had elevated sputum eosinophilic count as compared to ATA-CRSwNP and HC (median NERD 9.1%, ATA-CRSwNP 2.1%, and HC 0.4%; P<0.01). Baseline ISS levels of PGE2 were higher in asthmatics as compared to HC at baseline (NERD vs HC P=0.04, ATA-CRSwNP vs HC P<0.05). Post-challenge ISS levels of PGE2 compared to baseline significantly decreased in NERD and HC (P<0.01 and P=0.01), but not in ATA-CRSwNP. In NERD, a similar decrease in PGE2 as in HC resulted from 2.8 times lower dose of aspirin. Aspirin-precipitated bronchoconstriction is associated with a decrease in airway PGE2 biosynthesis. These results support the mechanism of PGE2 biosynthesis inhibition as a trigger for bronchoconstriction in NERD.

Abstract P149: VEGF Inhibitor-Induced Hypertension and Renal Injury: Prevention by Aspirin?

Vascular endothelial growth factor inhibitor (VEGFi)-induced hypertension and renal injury in cancer patients mimic the clinical phenotype of preeclampsia. ET-1 has been implicated to be involved. Since aspirin can prevent the onset of preeclampsia, we hypothesized that co-treatment of the VEGFi sunitinib (SU) with aspirin might be beneficial and may improve ET-1 status. Male WKY rats were treated with vehicle, 14 mg/kg/day SU, or SU + low or high dose aspirin (5 or 100 mg/kg/day) for 8 days. Mean arterial pressure (MAP) was measured via radiotelemetry. On day 8, 24h urine was collected to determine albuminuria and prostanoid (PGF2α and TxB2) levels. Plasma endothelin-1 (ET-1) was measured via ELISA. Endothelial dysfunction was assessed in iliac vessels and reactive oxygen species (ROS) was measured via aortic superoxide anion production. Renal cyclooxygenase (COX)-1, COX-2 and ET-1 mRNA expression were determined via PCR. SU induced a rapid and sustained increase in MAP (24±2 versus 1±1 mmHg in vehicle on day 6; P&lt;0.001), which was blunted by both low and high aspirin doses (18±3 and 13±4 mmHg respectively on day 6; P&lt;0.05 versus SU). Plasma ET-1 was increased by SU (2.2±0.3 versus 1.4±0.1 pg/ml in vehicle; P&lt;0.05) and this was not affected by aspirin. SU increased albuminuria (1.2±0.2 versus 0.3±0.1 mg/24h in vehicle; P&lt;0.05) which was prevented by high, but not low dose aspirin (0.5±0.1 and 1.3±0.1 mg/24h, respectively), suggesting that this effect is COX-2 dependent. Although renal mRNA expression levels were unchanged, renal COX-2 and ET-1 mRNA expression correlated positively, suggesting that ET-1 upregulates COX-2. SU increased ROS production 2.5-fold (P&lt;0.05 versus vehicle) and this was prevented by both aspirin doses. SU did not induce endothelial dysfunction, nor did it alter prostanoid levels. However, both aspirin doses reduced TxB2 (P&lt;0.05 versus vehicle). In conclusion, high rather than low dose aspirin was more efficacious for the prevention of VEGFi-induced hypertension and renal injury, suggesting that its beneficial effects largely involve COX-2 inhibition. Aspirin may be a novel intervention to allow cancer patients to gain the full benefit of VEGFi without deleterious cardiovascular and renal side effects.

VITAMIN D DEFICIENCY CAUSES INWARD HYPERTROPHIC REMODELING AND ALTERS VASCULAR REACTIVITY OF RAT CEREBRAL ARTERIOLES

Background and purpose Vitamin D deficiency (VDD) is a global health problem, which can lead to several pathophysiological consequences including cardiovascular diseases. Its impact on the cerebrovascular system is not well understood. The goal of the present work was to examine the effects of VDD on the morphological, biomechanical and functional properties of cerebral arterioles. Methods Four-week-old male Wistar rats (n = 11 per group) were either fed with vitamin D deficient diet or received conventional rat chow with per os vitamin D supplementation. Cardiovascular parameters and hormone levels (testosterone, androstenedione, progesterone and 25-hydroxyvitamin D) were measured during the study. After 8 weeks of treatment anterior cerebral artery segments were prepared and their morphological, biomechanical and functional properties were examined using pressure microangiometry. Resorcin-fuchsin and smooth muscle actin staining were used to detect elastic fiber density and smooth muscle cell counts in the vessel wall, respectively. Sections were immunostained for eNOS and COX-2 as well. Results VDD markedly increased the wall thickness, the wall-to-lumen ratio and the wall cross-sectional area of arterioles as well as the number of smooth muscle cells in the tunica media. As a consequence, tangential wall stress was significantly lower in the VDD group. In addition, VDD increased the myogenic as well as the uridine 5’-triphosphate-induced tone and impaired bradykinin-induced relaxation. Decreased eNOS and increased COX-2 expression were also observed in the endothelium of VDD animals. Conclusions VDD causes inward hypertrophic remodeling due to vascular smooth muscle cell proliferation and enhances the vessel tone probably because of increased vasoconstrictor prostanoid levels in young adult rats. In addition, the decreased eNOS expression results in endothelial dysfunction. These morphological and functional alterations can potentially compromise the cerebral circulation and lead to cerebrovascular disorders in VDD.

The antipyretic effect of paracetamol occurs independent of transient receptor potential ankyrin 1-mediated hypothermia and is associated with prostaglandin inhibition in the brain.

The mode of action of paracetamol (acetaminophen), which is widely used for treating pain and fever, has remained obscure, but may involve several distinct mechanisms, including cyclooxygenase inhibition and transient receptor potential ankyrin 1 (TRPA1) channel activation, the latter being recently associated with paracetamol's propensity to elicit hypothermia at higher doses. Here, we examined whether the antipyretic effect of paracetamol was due to TRPA1 activation or cyclooxygenase inhibition. Treatment of wild-type and TRPA1 knockout mice rendered febrile by immune challenge with LPS with a dose of paracetamol that did not produce hypothermia (150 mg/kg) but is known to be analgetic, abolished fever in both genotypes. Paracetamol completely suppressed the LPS-induced elevation of prostaglandin E2 in the brain and also reduced the levels of several other prostanoids. The hypothermia induced by paracetamol was abolished in mice treated with the electrophile-scavenger N-acetyl cysteine. We conclude that paracetamol's antipyretic effect in mice is dependent on inhibition of cyclooxygenase activity, including the formation of pyrogenic prostaglandin E2, whereas paracetamol-induced hypothermia likely is mediated by the activation of TRPA1 by electrophilic metabolites of paracetamol, similar to its analgesic effect in some experimental paradigms.-Mirrasekhian, E., Nilsson, J. L. Å., Shionoya, K., Blomgren, A., Zygmunt, P. M., Engblom, D., Högestätt, E. D., Blomqvist, A. The antipyretic effect of paracetamol occurs independent of transient receptor potential ankyrin 1-mediated hypothermia and is associated with prostaglandin inhibition in the brain.