Inhibitors Of Arachidonic Acid Metabolism Research Articles

EICOSATETRAYNOIC ACID REGULATES PRO-FIBROTIC PATHWAYS IN AN INDUCED PLURIPOTENT STEM CELL DERIVED MACROPHAGE:HUMAN INTESTINAL ORGANOID MODEL OF ILEAL CROHN’S DISEASE

Biologics targeting TNF are the mainstay of therapy for children with Crohn’s Disease (CD). However, a subset of patients do not respond, progressing to intestinal fibrosis requiring surgical resection. Prior studies have defined an ileal gene expression module linked to future strictures, and identified small molecules which may reverse this gene signature and suppress fibroblast activation. In the current study we developed a pre-clinical model system and tested a lead candidate, eicosatetraynoic acid (ETYA), a Peroxisome Proliferator-Activated Receptor (PPAR) agonist and arachidonic acid metabolism inhibitor.

Antioxidant and Anti-Inflammatory Properties of Phytochemicals Found in the Yucca Genus.

The Yucca genus encompasses about 50 species native to North America. Species within the Yucca genus have been used in traditional medicine to treat pathologies related to inflammation. Despite its historical use and the popular notion of its antioxidant and anti-inflammatory properties, there is a limited amount of research on this genus. To better understand these properties, this work aimed to analyze phytochemical composition through documentary research. This will provide a better understanding of the molecules and the mechanisms of action that confer such antioxidant and anti-inflammatory properties. About 92 phytochemicals present within the genus have reported antioxidant or anti-inflammatory effects. It has been suggested that the antioxidant and anti-inflammatory properties are mainly generated through its free radical scavenging activity, the inhibition of arachidonic acid metabolism, the decrease in TNF-α (Tumor necrosis factor-α), IL-6 (Interleukin-6), iNOS (Inducible nitric oxide synthase), and IL-1β (Interleukin 1β) concentration, the increase of GPx (Glutathione peroxidase), CAT (Catalase), and SOD (Superoxide dismutase) concentration, and the inhibition of the MAPK (Mitogen-Activated Protein Kinase), and NF-κB (Nuclear factor kappa B), and the activation of the Nrf2 (Nuclear factor erythroid 2-related factor) signaling pathway. These studies provide evidence of its use in traditional medicine against pathologies related to inflammation. However, more models and studies are needed to properly understand the activity of most plants within the genus, its potency, and the feasibility of its use to help manage or treat chronic inflammation.

EICOSATETRAYNOIC ACID REGULATES PRO-FIBROTIC PATHWAYS IN AN INDUCED PLURIPOTENT STEM CELL DERIVED MACROPHAGE:HUMAN INTESTINAL ORGANOID MODEL OF ILEAL CROHN’S DISEASE

Abstract INTRODUCTION Biologics targeting TNF are the mainstay of therapy for children with Crohn’s Disease (CD). However, a subset of patients do not respond, progressing to intestinal fibrosis requiring surgical resection. Prior studies have defined an ileal gene expression module linked to future strictures, and identified small molecules which may reverse this gene signature and suppress fibroblast activation. In the current study we developed a pre-clinical model system and tested a lead candidate, eicosatetraynoic acid (ETYA), a Peroxisome Proliferator-Activated Receptor (PPAR) agonist and arachidonic acid metabolism inhibitor. METHODS Peripheral blood samples were collected from pediatric CD patients and induced pluripotent stem cell (iPSC) lines were generated. iPSC were differentiated into human intestinal organoids (HIOs) and macrophage-like cells. Macrophage:HIO co-cultures were exposed to lipopolysaccharide (LPS) with and without eicosatetraynoic acid (ETYA) pre-treatment. Flow cytometry and cytospin characterized macrophage activation markers and morphology. Co-culture populations were harvested, and RNA and conditioned media were isolated for downstream analysis. TaqMan Low Density Array, Luminex multiplex assay, immunohistologic staining, and sirius red polarized light microscopy were performed to quantify measures of inflammation and fibrosis, and to test whether introduction of ETYA abated any of these inflammatory or fibrotic changes. RESULTS iPSC-derived macrophages exhibited morphology similar to primary macrophages, and expressed inflammatory macrophage cell surface markers including CD68 (Fig. 1A). LPS-stimulated iPSC-derived macrophages expressed a global pattern of gene expression by RNA sequencing enriched in CD ileal inflammatory macrophages (ToppCell Atlas, p=4.397E-117), and produced cytokines and chemokines implicated in refractory disease (Fig. 1B). Co-culture of LPS-primed macrophages with HIO led to up-regulation of the fibroblast activation genes ACTA2 and COL1A1 (Fig. 2). Under these conditions, HIO collagen content measured by sirius red staining and polarized light microscopy was increased (Fig. 2). ETYA pre-treatment prevented these pro-fibrotic effects of LPS-primed macrophages upon HIO gene expression and collagen content. However, LPS induction of macrophage IL1B, TNF, and OSM production was not suppressed by ETYA, suggesting an alternative mechanism of action upon HIO fibroblast activation and collagen content in the co-culture system. CONCLUSIONS ETYA inhibits effects of LPS-primed macrophages upon HIO pro-fibrotic gene expression and collagen production. This was not associated with an effect of ETYA upon macrophage inflammatory cytokine production. Future studies will test alternate pathways including PPAR activation and arachidonic acid metabolism which may mediate this response.

2-Methoxyestradiol Ameliorates Angiotensin II-Induced Hypertension by Inhibiting Cytosolic Phospholipase A2α Activity in Female Mice.

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6β-Hydroxytestosterone Promotes Angiotensin II-Induced Hypertension via Enhanced Cytosolic Phospholipase A2α Activity.

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Immuno-Resolving Ability of Resolvins, Protectins, and Maresins Derived from Omega-3 Fatty Acids in Metabolic Syndrome.

Omega-3 fatty acid consumption has been suggested to be beneficial for the prevention of type 2 diabetes mellitus (T2DM). Its effects have been attributed to anti-inflammatory activity, with the inhibition of arachidonic acid metabolism playing a central role. However, a more recent view is that omega-3 fatty acids play an active role as the precursors of potent, specialized pro-resolving mediators (SPMs), such as resolvins, protectins, and maresins. Docosahexaenoic acid (DHA)- and eicosapentaenoic-acid-derived SPMs are identified in the adipose tissue but the levels of certain SPMs (e.g., protectin D1) are markedly reduced with obesity, suggesting adipose SPM deficiency, potentially resulting in unresolved inflammation. Supplementation of the biosynthetic intermediates of SPM (e.g., 17-hydroxy-DHA) or omega-3 fatty acids increases the level of adipose SPMs, reduces adipose inflammation (decrease in macrophage accumulation and change to less inflammatory macrophages), and enhances insulin sensitivity. The findings from studies using rodent obesity models must be translated to humans. It will be important to further elucidate the underlying mechanisms by which obesity reduces the levels of and the sensitivity to SPM in adipose tissues. This will enable the development of nutrition therapy to enhance the effects of omega-3 fatty acids in the prevention and/or treatment of T2DM.

Cytokine and inflammatory mediator effects on TRPV4 function in choroid plexus epithelial cells.

The choroid plexus (CP), composed of capillaries surrounded by a barrier epithelium, is the main producer of cerebrospinal fluid (CSF). The CP epithelium regulates the transport of ions and water between the blood and the ventricles, contributing to CSF production and composition. Several studies suggest a connection between the cation channel transient receptor potential vanilloid-4 (TRPV4) and transepithelial ion movement. TRPV4 is a nonselective, calcium-permeable cation channel present in CP epithelia reported to be activated by cytokines and inflammatory mediators. Utilizing the PCP-R (porcine choroid plexus-Riems) cell line, we investigated the effects of various cytokines and inflammatory mediators on TRPV4-mediated activity. Select proinflammatory cytokines (TNF-α, IL-1β, TGF-β1) had inhibitory effects on TRPV4-stimulated transepithelial ion flux and permeability changes, whereas anti-inflammatory cytokines (IL-10, IL-4, and IL-6) had none. Quantitative mRNA analysis showed that these cytokines had no effect on TRPV4 transcription levels. Inhibition of the transcription factor NF-κB, involved in the production and regulation of several inflammatory cytokines, inhibited TRPV4-mediated activity, suggesting a link between TRPV4 and cytokine production. Contrary to published studies, the proinflammatory mediator arachidonic acid (AA) had inhibitory rather than stimulatory effects on TRPV4-mediated responses. However, inhibition of AA metabolism also caused inhibitory effects on TRPV4, suggesting a complex interaction of AA and its metabolites in the regulation of TRPV4 activity. Together these data imply that TRPV4 activity is involved in the inflammatory response; it is negatively affected by proinflammatory mediators. Furthermore, arachidonic acid metabolites, but not arachidonic acid itself, are positive regulators of TRPV4.

Anti-inflammatory activity of herb products from Licania rigida Benth.

PurposeThe objective of the present study was to evaluate the systemic anti-inflammatory activity of the hydroalcoholic extract of the leaves of Licania rigida Benth (EHFLR) on models of systemic inflammation in mice. MethodsThe quantitative chemical profiles of phenolic acids and flavonoids were performed by High-Performance Liquid Chromatography (HPLC). Systemic anti-inflammatory activity was determined from carrageenan and dextran-induced paw edema models and the animals were orally treated (p.o.) with EHFLR at doses of 25, 50, 100 mg/kg, indomethacin (10 mg/kg) for carrageenan-induced paw edema and promethazine (6 mg/kg) for dextran-induced paw edema. The possible mechanisms involved in the anti-inflammatory action of the extract were evaluated by the paw edema models induced by histamine and arachidonic acid, and by the model of carrageenan-induced peritonitis, where vascular permeability and leukocyte migration to the peritoneal cavity were evaluated. ResultsThe results of the HPLC identified the presence of phenolic acids and flavonoids, with chlorogenic acid (1.16%) and Caempferol (0.81%) as the main constituents. From the results, it was concluded that the extract has an LD50 ≥5000 mg/kg when administered orally in mice as this dose did not trigger deaths in any of the observed groups. EHFLR (25 mg/kg) showed a significant antiderematogenic effect on histamine and arachidonic acid-induced paw edema at the third hour of the tests, with a percentage of inhibition of 46.64% and 18.33%, respectively. The extract (25 mg/kg, p.o.) also significantly reduced vascular permeability and leukocyte migration in the peritoneal cavity. ConclusionsIt is concluded that EHFLR exerts a systemic anti-inflammatory action, which seems to depend, at least in part, on the inhibition of arachidonic acid metabolism and the action of vasoactive amines. In addition, the extract reduced the leukocyte migration in the peritoneal cavity, indicating that its action may be linked to the inhibition of pro-inflammatory cytokines.

Maternal recognition of pregnancy

Enhanced secretion of PGF2 alpha from endometrial explants in vitro in response to oxytocin is associated with augmented activities of phospholipase A2, phospholipase C and prostaglandin endoperoxide H synthase (PGS). In early pregnancy, maintenance of the corpus luteum is associated with an absence of pulsatile PGF2 alpha secretion; an increase in endometrial inhibitors of phospholipase A2 and PGS contribute to the antiluteolytic alterations of PGF2 alpha secretion. Linoleic acid is a competitive inhibitor of arachidonic acid metabolism by PGS, and microsomal concentrations of free linoleic acid are increased in the endometrium of pregnant cattle. The trophoblast produces large quantities of interferon tau (IFN-tau). Inhibition of increases in endometrial oestradiol receptor mRNA and protein are associated with intrauterine administration of recombinant (r) ovine (o) IFN-tau in sheep. Intrauterine injections of ovine (b) IFN-tau in cattle (days 14-17) altered endometrial function so that secretion of PGF2 alpha from cultured endometrial epithelial cells was reduced. Antiluteolytic effects were not expressed in 20% of cows receiving IFN-tau or rbIFN-alpha I1 indicating that an inadequate endometrial responsiveness may contribute to embryo mortality. IFN-tau may activate a signal transduction system similar to that induced by other type I IFNs; activation of an intracellular tyrosine kinase ultimately leads to activation of an IFN-stimulated response element to induce gene transcription. Biological responses associated with pregnancy and IFN-tau treatment are integrated into a multifactorial antiluteolytic model. Strategies to enhance embryo survival could include supplementation with rIFN-tau and alterations in endometrial responsiveness to this cytokine through dietary manipulation of lipid metabolism.

3019 Metabolomic Markers of Methotrexate Response in Juvenile Idiopathic Arthritis

OBJECTIVES/SPECIFIC AIMS: In this study, a semi-targeted metabolomics approach is used to identify metabolic markers of methotrexate (MTX) response in juvenile idiopathic arthritis (JIA) and in vitro. METHODS/STUDY POPULATION: A comparative metabolomic analysis was used to identify metabolomic markers and metabolic pathways associated with MTX activity in vitro and in vivo. Cell-based studies assessed metabolomic profiles in K562 erythroblastoid cells with or without MTX treatment. In vivo analysis utilized plasma samples from JIA patients treated with MTX (n=30) and included samples collected prior to the initiation of MTX and after 3-months of MTX treatment. Plasma samples were from an IRB-approved single center prospective cohort study of biomarkers of MTX response in patients with JIA and were stratified based on American College of Rheumatology pediatric (ACR Pedi) response criteria. Semi-targeted global metabolomic profiles including over 800 metabolites across three analytical platforms at the NIH West Coast Metabolomics Center at UC-Davis and were analyzed by univariate and multivariate analysis using MetaboAnalyst 3.0. RESULTS/ANTICIPATED RESULTS: In K562 cells, MTX treatment was associated with statistically significant changes in 550 of the 850 intracellular metabolites detected (false discovery rate less than 0.05). Major metabolic pathways inhibited by MTX included branched-chain amino acid metabolism, purine and pyrimidine biosynthesis, and lipid metabolism including the inhibition of arachidonic acid metabolism. In patients with JIA, far fewer plasma metabolites were significantly altered following the initiation of MTX and included only 15 of the 833 plasma metabolites detected. Interestingly, MTX treatment was associated with the inhibition of arachidonic acid synthesis, inhibition of purine metabolism, and a dramatic reduction in plasma levels of various exogenous metabolites. In particular, MTX treatment was associated reductions in known metabolic markers of intestinal microbiota metabolism, including: biotin and dehydrocholic acid. Further, stratification of patients based on ACR Pedi response demonstrated that clinical response was associated with a greater reduction in plasma dehydrocholic acid levels following the initiation of MTX. DISCUSSION/SIGNIFICANCE OF IMPACT: This work demonstrates that MTX therapy is associated with a number of biochemical changes in vitro and in vivo, including: inhibition of purine metabolism, inhibition of arachidonic acid metabolism, and an apparent inhibition of gut microbiota metabolism. Most notably, inhibition of gut microbiota metabolism appears to demonstrate a relationship with the observed clinical efficacy of MTX in JIA.

Abstract P303: Inhibition of Group IV Cytosolic Phospholipase A 2 α by Cytochrome P450 1B1-Estradiol Derived Metabolite 2-Methoxyestradiol Protects Against Angiotensin II-Induced Hypertension in Female Mice

Previously we showed that the protection against angiotensin (Ang) II-induced hypertension and associated pathophysiological changes in female mice are mediated by cytochrome P450 (CYP) 1B1-estradiol (E2) generated metabolite 2-methoxyestradiol (2-ME). Also, we demonstrated that Ang II-induced hypertension is mediated by group IV cytosolic phospholipase A 2 α (cPLA 2 α) activation resulting in arachidonic acid (AA) release, and generation predominantly of eicosanoids with pro-hypertensive effects in male mice. This study was conducted to determine the contribution of cPLA 2 α/AA system, and its relationship to CYP1B1 in Ang II-induced hypertension in the female mice. Ang II infusion (700 ng/kg/min, s.c. micro-osmotic pump) for 14 days increased the systolic blood pressure (SBP), measured by tail-cuff in wild-type mice (cPLA 2 α +/+ ) but not in cPLA 2 α gene-disrupted mice (cPLA 2 α -/- ) (151±8 vs. 126±9 mmHg, P <0.05, n=4-5). Ang II markedly increased SBP in ovariectomized (OVX) cPLA 2 α +/+ mice but not in OVX cPLA 2 α -/- mice (175±3 vs. 121±2 mmHg, P <0.05, n=4-5). AA metabolism inhibitor 5,8,11,14-eicosatetraynoic acid (ETYA, 50 mg/kg, i.p. every 3 rd day) attenuated ( P <0.05) the Ang II-induced increase in SBP in intact (124±5 mmHg, n=5) and OVX cPLA 2 α +/+ mice (124±5 mmHg, n=4). E2 attenuated Ang II-induced increase in SBP in OVX Cyp1b1 +/+ mice, but not in OVX Cyp1b1 -/- mice (125±5 vs. 158±4 mmHg, P <0.05, n=3-4). Ang II-induced increase in SBP was also attenuated by ETYA in the Cyp1b1 -/- mice (129±7 vs. 185±7 mmHg, P <0.05, n=4). Ang II-induced increase in cPLA 2 α +/+ activity examined in the kidneys was inhibited in Cyp1b1 -/- mice treated with 2-ME. Antagonists of prostaglandin (PG) E2 receptors EP1 (SC19220) and EP3 (L-798106) (28 μg/g, s.c. every 2 nd day) minimized Ang II-induced increase in SBP in OVX cPLA 2 α +/+ mice (126±2 and 127±5 vs. 175±3 mmHg, respectively, n=5). These data suggest that CYP1B1-E2 generated metabolite 2-ME protects against Ang II-induced hypertension by inhibiting cPLA 2 α activity and production of AA-derived PGE2 that exerts pro-hypertensive effects by stimulating EP1 and EP3 receptors. Thus, 2-ME and the drugs that selectively block EP1 and EP3 receptors could be useful for the treatment of hypertension and its pathogenesis in females.

MiR-146a suppresses 5-lipoxygenase activating protein (FLAP) expression and Leukotriene B4 production in lung cancer cells.

Arachidonic acid (AA) can be converted into prostaglandins (PGs) or leukotrienes (LTs) by the enzymatic actions of cyclooxygenases (COX-1 and COX-2) or 5-lipoxygenase (5-LO), respectively. PGs and LTs are lipid signaling molecules that have been implicated in various diseases, including multiple cancers. 5-LO and its activating protein (FLAP) work together in the first two conversion steps of LT production. Previous work has suggested a role for LTs in cancer development and progression. MicroRNAs (miRNAs) are small RNA molecules that negatively regulate gene expression post-transcriptionally, and have previously been shown to be involved in cancer. Here, we show that high FLAP expression is associated with lower overall survival in lung adenocarcinoma patients, and FLAP protein is overexpressed in lung cancer cells compared to normal lung cells. Our lab has previously shown that miR-146a regulates COX-2 in lung cancer cells, and this miRNA is also predicted to target FLAP. Transient and stable transfections of miR-146a repress endogenous FLAP expression in lung cancer cells, and reporter assays show this regulation occurs through a direct interaction between the FLAP 3′ untranslated region (UTR) and miR-146a. Restoration of miR-146a also results in decreased cancer cell Leukotriene B4 (LTB4) production. Additionally, methylation analysis indicates the miR-146a promoter is hypermethylated in lung cancer cell lines. Taken together, this study and previous work from our lab suggest miR-146a is an endogenous dual inhibitor of AA metabolism in lung cancer cells by regulating both PG and LT production through direct targeting of the COX-2 and FLAP 3’ UTRs.

Abstract P473: Group IV Cytosolic Phospholipase A2α is Critical for Norepinephrine-Induced Hypertension

Previously we reported that angiotensin (Ang) II-induced hypertension and associated cardiovascular and renal dysfunction are mediated by cytosolic phospholipase A 2 α (cPLA 2 α) activation, the release of arachidonic acid (AA), and production of eicosanoids predominantly with pro-hypertensive effects ( Hypertension. 2015; 65: 784-792; 2016; 29: 258-265 ). We have also shown that norepinephrine (NE) by activating cPLA 2 releases AA, and production of prostanoids in vascular smooth muscle cells ( J Biol Chem. 1996; 217:30149-30157; J. Pharmacol. Exp. Ther. 1993; 266: 1113–1124 ). This study was conducted to determine the contribution of cPLA 2 α in NE-induced hypertension. Eight weeks old male wild-type (cPLA 2 α +/+ ) and cPLA 2 α gene disrupted (cPLA 2 α -/- ) mice were infused with NE (10 mg/kg/day, s.c.) or its vehicle using mini-osmotic pumps for 2 weeks, and the systolic blood pressure (SBP) was measured by tail-cuff. Infusion of NE increased the SBP in cPLA 2 α +/+ mice (148±3 vs. 118±3 mmHg, P<0.05, n=4-5); but not in cPLA 2 α -/- mice (122±5 mmHg, n=5). The NE-induced increase in SBP was minimized by treatment with AA metabolism inhibitor, 5,8,11,14-eicosatetraynoic acid (ETYA) (25 mg/kg, i.p., every 3 rd day) in cPLA 2 α +/+ mice (125±5 vs. 148±3 mmHg, P<0.05, n=4-5). Prostaglandin (PG) E2-EP1 and EP3 receptor activation that increase blood pressure have been implicated in Ang II-induced hypertension. In our study antagonists of the EP3 receptor (L-798106) (10 mg/kg, i.p. every 3 rd day) decreased the NE-induced increase in SBP (130±5 vs. 148±3 mmHg, P<0.05, n=5/group). These data suggest that cPLA 2 α contributes to NE-induced increase in SBP via cPLA 2 α activation, the release of AA and generation of eicosanoids, most likely PGE2 that exerts pro-hypertensive effects by stimulating EP3 receptors. Therefore, the development of agents that selectively inhibit the cPLA 2 α activity or block EP3 receptors could be useful in treating hypertension and its pathogenesis.

1072 Evaluation of immune function of circulating leukocytes during the transition period in dairy cows

The aims of the study were to determine immune function circulating leukocytes using an ex vivowhole blood stimulation assay (WBA) with lipopolysaccharide (LPS) and assess gene expression profiles by RNA sequencing in the transition period of dairy cows. The WBA was performed on whole blood of 6 Holstein multiparous cows at −20, −3, 3, 7 d from parturition (DFP) using 0, 0.01 and 5 µg LPS/mL. The plasma collected after stimulation was used to analyze IL-1β and IL-6 concentration via ELISA. The data were analyzed as a factorial design with repeated measures, using PROC MIXED in SAS. At the same day of the WBA test, RNA was isolated from whole blood and sequenced on a Hiseq1000 (Illumina, USA). Differential gene expression analysis was conducted with the edgeR package, and a general linear model was applied considering −20 DFP as the baseline. A threshold of 1.5-fold change and P < 0.05 were used to define differentially expressed genes (DEG), which were subsequently analyzed through the Dynamic Impact Approach (DIA) using the Kyoto Encyclopedia of Genes and Genomes (KEGG) database. The IL-1b and IL-6 released after LPS stimulation was higher at −3 DFP (P < 0.05) in comparison with −20 DFP. After calving, the response of IL-1β to stimulation of LPS decreased markedly, while the IL-6 response was unchanged up to 3 DFP (P < 0.01 vs. -20 DFP) and then declined at 7 DFP. The most-impacted and activated KEGG pathways highlighted by the DIA analysis at −3 vs. −20 DFP were: PPAR signaling, adipocytokine signaling, hematopoietic cell lineage, ECM-receptor interaction and phagosome. After calving (3 and 7 DFP) the impact and activation of the above listed pathways was strongly increased, but there also was a strong inhibition of arachidonic acid metabolism (in particular enzymes regulating leukotrienes synthesis) as well as glycine, serine and threonine metabolism. Overall, the WBA and transcriptomic data confirmed changes in immune-competence of the circulating leukocytes around calving and, in particular, indicate mainly an increase of their activity and function. These data support the idea that the dairy cow's immune system is dysfunctional but not immunosuppressed around calving.

Computational Modeling of Competitive Metabolism between ω3- and ω6-Polyunsaturated Fatty Acids in Inflammatory Macrophages.

Arachidonic acid (AA), a representative ω6-polyunsaturated fatty acid (PUFA), is a precursor of 2-series prostaglandins (PGs) that play important roles in inflammation, pain, fever, and related disorders including cardiovascular diseases. Eating fish or supplementation with the ω3-PUFAs such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) is widely assumed to be beneficial in preventing cardiovascular diseases. A proposed mechanism for a cardio-protective role of ω3-PUFAs assumes competition between AA and ω3-PUFAs for cyclooxygenases (COX), leading to reduced production of 2-series PGs. In this study, we have used a systems biology approach to integrate existing knowledge and novel high-throughput data that facilitates a quantitative understanding of the molecular mechanism of ω3- and ω6-PUFA metabolism in mammalian cells. We have developed a quantitative computational model of the competitive metabolism of AA and EPA via the COX pathway through a two-step matrix-based approach to estimate the rate constants. This model was developed by using lipidomic data sets that were experimentally obtained from EPA-supplemented ATP-stimulated RAW264.7 macrophages. The resulting model fits the experimental data well for all metabolites and demonstrates that the integrated metabolic and signaling networks and the experimental data are consistent with one another. The robustness of the model was validated through parametric sensitivity and uncertainty analysis. We also validated the model by predicting the results from other independent experiments involving AA- and DHA-supplemented ATP-stimulated RAW264.7 cells using the parameters estimated with EPA. Furthermore, we showed that the higher affinity of EPA binding to COX compared with AA was able to inhibit AA metabolism effectively. Thus, our model captures the essential features of competitive metabolism of ω3- and ω6-PUFAs.

5,7-dihydroxy-2-(3-hydroxy-4, 5-dimethoxy-phenyl)-chromen-4-one-a flavone from Bruguiera gymnorrhiza displaying anti-inflammatory properties.

Objective:Bruguiera gymnorrhiza (BRG) (L.) Lamk (Rhizophoraceae), a mangrove species, is widely distributed in the Pacific region, eastern Africa, Indian subcontinent, and subtropical Australia. The leaves of this plant are traditionally used for treating burns and inflammatory lesions. This study isolates the bioactive compound from the methanol extract of BRG leaves and evaluates the possible mechanisms of anti-inflammatory activity involved.Materials and Methods:Bioassay-guided fractionation of BRG was performed to identify the bioactive fraction (displaying inhibition of cyclooxygenase 2 [COX2] - 5-lipoxygenase (5-LOX) activities and tumor necrosis factor-alpha (TNF-α) production at the tested concentrations of 100 and 10 μg/ml). The fractionation was performed by solvent extraction and preparative high-performance liquid chromatography. The bioactive compound was characterized by ultraviolet–visible, liquid chromatography–mass spectrometry and nuclear magnetic resonance spectroscopy. The antioxidant potential was evaluated by electron spin resonance spectrum of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical at 250 μM. The effect of the compound was also studied on TNF-α converting enzyme and nuclear factor kappa B (NF-κB) activities at the concentrations 100, 10 and 1 μg/ml.Results:Bioassay-guided purification of BRG revealed the presence of a flavone (5,7-dihydroxy-2- [3-hydroxy-4,5-dimethoxy-phenyl]-chromen-4-one) of molecular weight 330Da. It demonstrated more than 80% inhibition against COX2, 5-LOX activities and TNF-α production at 100 μg/ml. It also displayed 40% inhibition against DPPH radical at the tested concentration along with 23.1% inhibition of NF-κB activity at 100 μg/ml.Conclusions:The isolated methoxy-flavone may play a predominant role in the anti-inflammatory properties displayed by BRG leaves. Such activity may involve multiple mechanisms, namely (a) modulation of oxidative stress (b) inhibition of arachidonic acid metabolism and (c) downregulation of pro-inflammatory cytokines probably through NF-κB inhibition.

Regulation of cAMP Intracellular Levels in Human Platelets Stimulated by 2-Arachidonoylglycerol.

We demonstrated that in human platelets the endocannabinoid 2-arachidonoylglycerol (2-AG) decreased dose- and time-dependently cAMP intracellular levels. No effect on cAMP decrease induced by 2-AG was observed in the presence of the adenylate cyclase inhibitor SQ22536 as well in platelets pretreated with the thromboxane A2 receptor antagonist, SQ29548 or with aspirin, inhibitor of arachidonic acid metabolism through the cyclooxygenase pathway. An almost complete recovering of cAMP level was measured in platelets pretreated with the specific inhibitor of phosphodiesterase (PDE) 3A, milrinone. In platelets pretreated with LY294002 or MK2206, inhibitors of PI3K/AKT pathway, and with U73122, inhibitor of phospholipase C pathway, only a partial prevention was shown. cAMP intracellular level depends on synthesis by adenylate cyclase and hydrolysis by PDEs. In 2-AG-stimulated platelets adenylate cyclase activity seems to be unchanged. In contrast PDEs appear to be involved. In particular PDE3A was specifically activated, as milrinone reversed cAMP reduction by 2-AG. 2-AG enhanced PDE3A activity through its phosphorylation. The PI3K/AKT pathway and PKC participate to this PDE3A phosphorylation/activation mechanism as it was greatly inhibited by platelet pretreatment with LY294002, MK2206, U73122, or the PKC specific inhibitor GF109203X. Taken together these data suggest that 2-AG potentiates its power of platelet agonist reducing cAMP intracellular level.

5-hydroxytryptamine has an endothelium-derived hyperpolarizing factor-like effect on coronary flow in isolated rat hearts

Background5-hydroxytryptamine (5-HT)-induced coronary artery responses have both vasoconstriction and vasorelaxation components. The vasoconstrictive effects of 5-HT have been well studied while the mechanism(s) of how 5-HT causes relaxation of coronary arteries has been less investigated. In isolated rat hearts, 5-HT-induced coronary flow increases are partially resistant to the nitric oxide synthase inhibitor Nω-Nitro-L-arginine methyl ester (L-NAME) and are blocked by 5-HT7 receptor antagonists. In the present study, we investigated the role of 5-HT7 receptor in 5-HT-induced coronary flow increases in isolated rat hearts in the absence of L-NAME, and we also evaluated the involvement of endothelium-derived hyperpolarizing factor (EDHF) in 5-HT-induced coronary flow increases in L-NAME-treated hearts with the inhibitors of arachidonic acid metabolism and the blockers of Ca2+-activated K+ channels.ResultsIn isolated rat hearts, 5-HT and the 5-HT7 receptor agonist 5-carboxamidotryptamine induced coronary flow increases, and both of these effects were blocked by the selective 5-HT7 receptor antagonist SB269970; in SB269970-treated hearts, 5-HT induced coronary flow decreases, which effect was blocked by the 5-HT2A receptor blocker R96544. In L-NAME-treated hearts, 5-HT-induced coronary flow increases were blocked by the phospholipase A2 inhibitor quinacrine and the cytochrome P450 inhibitor SKF525A, but were not inhibited by the cyclooxygenase inhibitor indomethacin. As to the effects of the Ca2+-activated K+ channel blockers, 5-HT-induced coronary flow increases in L-NAME-treated hearts were inhibited by TRAM-34 (intermediate-conductance Ca2+-activated K+ channel blocker) and UCL1684 (small-conductance Ca2+-activated K+ channel blocker), but effects of the large-conductance Ca2+-activated K+ channel blockers on 5-HT-induced coronary flow increases were various: penitrem A and paxilline did not significantly affect 5-HT-induced coronary flow responses while tetraethylammonium suppressed the coronary flow increases elicited by 5-HT.ConclusionIn the present study, we found that 5-HT-induced coronary flow increases are mediated by the activation of 5-HT7 receptor in rat hearts in the absence of L-NAME. Metabolites of cytochrome P450s, small-conductance Ca2+-activated K+ channel, and intermediate-conductance Ca2+-activated K+ channel are involved in 5-HT-induced coronary flow increases in L-NAME-treated hearts, which resemble the mechanisms of EDHF-induced vasorelaxation. The role of large-conductance Ca2+-activated K+ channel in 5-HT-induced coronary flow increases in L-NAME-treated hearts needs further investigation.

Cytosolic phospholipase A2α is critical for angiotensin II-induced hypertension and associated cardiovascular pathophysiology.

Angiotensin II activates cytosolic phospholipase A(2)α (cPLA2α) and releases arachidonic acid from tissue phospholipids, which mediate or modulate ≥1 cardiovascular effects of angiotensin II and has been implicated in hypertension. Because arachidonic acid release is the rate limiting step in eicosanoid production, cPLA2α might play a central role in the development of angiotensin II-induced hypertension. To test this hypothesis, we investigated the effect of angiotensin II infusion for 13 days by micro-osmotic pumps on systolic blood pressure and associated pathogenesis in wild type (cPLA2α(+/+)) and cPLA2α(-/-) mice. Angiotensin II-induced increase in systolic blood pressure in cPLA2α(+/+) mice was abolished in cPLA2α(-/-) mice; increased systolic blood pressure was also abolished by the arachidonic acid metabolism inhibitor, 5,8,11,14-eicosatetraynoic acid in cPLA2α(+/+) mice. Angiotensin II in cPLA2α(+/+) mice increased cardiac cPLA2 activity and urinary eicosanoid excretion, decreased cardiac output, caused cardiovascular remodeling with endothelial dysfunction, and increased vascular reactivity in cPLA2α(+/+) mice; these changes were diminished in cPLA2α(-/-) mice. Angiotensin II also increased cardiac infiltration of F4/80(+) macrophages and CD3(+) T lymphocytes, cardiovascular oxidative stress, expression of endoplasmic reticulum stress markers p58(IPK), and CHOP in cPLA2α(+/+) but not cPLA2α(-/-) mice. Angiotensin II increased cardiac activity of ERK1/2 and cSrc in cPLA2α(+/+) but not cPLA2α(-/-) mice. These data suggest that angiotensin II-induced hypertension and associated cardiovascular pathophysiological changes are mediated by cPLA2α activation, most likely through the release of arachidonic acid and generation of eicosanoids with predominant prohypertensive effects and activation of ≥1 signaling molecules, including ERK1/2 and cSrc.

Effects of Angiotensin II Receptor Blockers on Metabolism of Arachidonic Acid &lt;i&gt;via&lt;/i&gt; CYP2C8

Arachidonic acid (AA) is metabolized to epoxyeicosatrienoic acids (EETs) via cytochrome enzymes such as CYP 2C9, 2C8 and 2J2. EETs play a role in cardioprotection and regulation of blood pressure. Recently, adverse reactions such as sudden heart attack and fatal myocardial infarction were reported among patients taking angiotensin II receptor blockers (ARBs). As some ARBs have affinity for these CYP enzymes, metabolic inhibition of AA by ARBs is a possible cause for the increase in cardiovascular events. In this study, we quantitatively investigated the inhibitory effects of ARBs on the formation of EETs and further metabolites, dihydroxyeicosatrienoic acids (DHETs), from AA via CYP2C8. In incubations with recombinant CYP2C8 in vitro, the inhibitory effects were compared by measuring EETs and DHETs by HPLC-MS/MS. Inhibition of AA metabolism by ARBs was detected in a concentration-dependent manner with IC50 values of losartan (42.7 µM), telmisartan (49.5 µM), irbesartan (55.6 µM), olmesartan (66.2 µM), candesartan (108 µM), and valsartan (279 µM). Losartan, telmisartan and irbesartan, which reportedly accumulate in the liver and kidneys, have stronger inhibitory effects than other ARBs. The lower concentration of EETs leads to less protective action on the cardiovascular system and a higher incidence of adverse effects such as sudden heart attack and myocardial infarction in patients taking ARBs.