Determination of endogenous tissue inflammation profiles by LC/MS/MS: COX- and LOX-derived bioactive lipids

Unravelling bisphenol A-induced hepatotoxicity: Insights into oxidative stress, inflammation, and energy dysregulation

Bisphenol A (BPA), a prevalent plastic monomer and endocrine disruptor, negatively impacts metabolic functions. This study examines the chronic effects of eco-relevant BPA concentrations on hepatotoxicity, focusing on redox balance, inflammatory response, cellular energy sensors, and metabolic homeostasis in male Swiss albino mice. Chronic BPA exposure resulted in reactive oxygen species (ROS) accumulation, altered hepatic antioxidant defense, lipid peroxidation, and NOX4 expression, leading to reduced cell viability. Additionally, BPA exposure significantly upregulated hepatic pro-inflammatory cytokine genes (Tnf-α, Il-1β, Il-6), NOS2, and arginase II, correlating with increased TLR4 expression, NF-κB phosphorylation, and a dose-dependent decrease in IκBα levels. BPA-induced NF-κB nuclear localization and inflammasome activation (NLRP3, cleaved caspase-1, IL-1β) established an inflammatory milieu. Perturbations in hepatic AMPKα phosphorylation, SIRT1, and PGC-1α, along with elevated p38 MAPK phosphorylation and ERα expression, indicated BPA-induced energy dysregulation. Furthermore, increased PLA2G4A, COX1, COX2, and PTGES2 expression in BPA-treated liver correlated with hyperlipidemia, hepatic FASN expression, steatosis, and visceral adiposity, likely due to disrupted energy sensors, oxidative stress, and inflammasome activation. Elevated liver enzymes (ALP, AST, ALT) and apoptotic markers indicated liver damage. Notably, N-acetylcysteine (NAC) priming reversed BPA-induced hepatocellular ROS accumulation, NF-κB-inflammasome activation, and intracellular lipid accumulation, while upregulating cellular energy sensors and attenuating ERα expression, suggesting NAC's protective effects against BPA-induced hepatotoxicity. Pharmacological inhibition of the NF-κB/NLRP3 cascade in BAY11-7082 pretreated, or NLRP3 immunodepleted hepatocytes reversed BPA's negative impact on SIRT1/p-AMPKα/PGC-1α and intracellular lipid accumulation, providing mechanistic insights into BPA-induced metabolic disruption.

Protective Effect of the Polyphenol Ligustroside on Colitis Induced with Dextran Sulfate Sodium in Mice

Dietary polyphenols are reported to alleviate colitis by interacting with gut microbiota which plays an important role in maintaining the integrity of the intestinal barrier. As a type of dietary polyphenol, whether ligustroside (Lig) could alleviate colitis has not been explored yet. Here, we aimed to determine if supplementation of ligustroside could improve colitis. We explored the influence of ligustroside intake with different dosages on colitis induced with dextran sulfate sodium (DSS). Compared to the DSS group, supplementation of ligustroside could reduce body weight (BW) loss, decrease disease activity indices (DAI), and relieve colon damage in colitis mice. Furthermore, ligustroside intake with 2 mg/kg could decrease proinflammatory cytokine concentrations in serum and increase immunoglobulin content and antioxidant enzymes in colon tissue. In addition, supplementation of ligustroside (2 mg/kg) could reduce mucus secretion and prevent cell apoptosis. Also, changes were revealed in the bacterial community composition, microbiota functional profiles, and intestinal metabolite composition following ligustroside supplementation with 2 mg/kg using 16S rRNA sequencing and non-targeted lipidomics analysis. In conclusion, the results showed that ligustroside was very effective in preventing colitis through reduction in inflammation and the enhancement of the intestinal barrier. Furthermore, supplementation with ligustroside altered the gut microbiota and lipid composition of colitis mice.

Evaluation of the Protective Effect of Compound Kushen Injection Against Radiation- induced Pneumonitis in Mice

Background Radiation-induced lung injury (RILI) via inflammation is a common adverse effect of thoracic radiation that negatively impacts patient quality of life and survival. Compound kushen injection (CKI), a botanical drug treatment, was examined for its ability to reduce RILI, and inflammatory responses and improve survival in mice exposed total lung irradiation (TLI). CKI's specific mechanisms of action were also evaluated. Methods C3H mice underwent TLI and were treated with CKI (2, 4, or 8 mL/kg) intraperitoneally once a day for 8 weeks. The effects of CKI on survival were estimated by Kaplan-Meier survival analysis and compared by log-rank test. RILI damage was evaluated by histopathology and micro-computed tomography (CT). Inflammatory cytokines and cyclooxygenase metabolites were examined by IHC staining, western blot, and ELISA. Results Pre-irradiation treatment with 4 or 8 mL/kg CKI starting 2 weeks before TLI or concurrent treatment with 8 mL/kg CKI were associated with a significantly longer survival compared with TLI vehicle-treated group ( P  < 0.05). Micro-CT images evaluations showed that concurrent treatment with 8 mL/kg CKI was associated with significantly lower incidence of RILI ( P  < 0.05). Histological evaluations revealed that concurrent TLI treatment of CKI (4 and 8 mL/kg) significantly reduced lung inflammation (p < 0.05). Mechanistic investigation showed that at 72 hours after radiation, TLI plus vehicle mice had significantly elevated serum IL6, IL17A, and TGF-β levels compared with non-irradiated, age-matched normal mice; in contrast, levels of these cytokines in mice that received TLI plus CKI treatment were lower than those in the TLI plus vehicle-treated mice ( P  < 0.05) and similar to the nonirradiated mice. IHC staining showed that the CKI treatment led to a reduction of TGF-β positive cells in the lung tissues of TLI mice (P < 0.01). The concurrent CKI with TLI treatment group had a significant reduction in COX-2 activity and COX-2 metabolites compared with the TLI vehicle-treated group ( P  < 0.05). Conclusions These data suggest that CKI treatment was associated with reduced radiation-induced inflammation in lung tissues, reduced RILI, and improved survival. Further investigation of CKI in human clinical trials as a potential radioprotector against RILI to improve patients' quality of life and survival is warranted.

The enantioselective separation and quantitation of the hydroxy-metabolites of arachidonic acid by liquid chromatography - tandem mass spectrometry

Arachidonic acid (AA) is a polyunsaturated fatty acid with a structure of 20:4(ω-6). Cytochrome P450s (CYPs) metabolize AA to several regioisomers and enantiomers of hydroxyeicosatetraenoic acids (HETEs). The hydroxy-metabolites (HETEs) exist as enantiomers in the biological system. The chiral assays developed for HETEs are so far limited to a few assays reported for midchain HETEs. The developed method is capable of quantitative analysis for midchain, subterminal HETE enantiomers, and terminal HETEs in microsomes. The peak area or height ratios were linear over concentrations ranging (0.01 -0.6 µg/ml) with r2 > 0.99. The intra-run percent error and coefficient of variation (CV) were ≤ ± 12 %. The inter-run percent error and coefficient of variation (CV)were ≤ ± 13 %, and ≤ 15 %, respectively. The matrix effect for the assay was also within the acceptable limit (≤ ± 15 %). The recovery of HETE metabolites ranged from 70 % to 115 %. The method showed a reliable and robust performance for chiral analysis of cytochrome P450-mediated HETE metabolites.

Protective Effect of l-Theanine against DSS-Induced Colitis by Regulating the Lipid Metabolism and Reducing Inflammation via the NF-κB Signaling Pathway

The present study revealed the phylactic effects of l-theanine on a DSS-induced colitis mice model. The results showed that 3% DSS treatment significantly induced intestinal damage as reflected by DAI, histopathological feature, and colon length, while l-theanine pretreatment markedly prevented these trends to exert protective effects. Meanwhile, l-theanine pretreatment decreased the levels of TNF-α, IL-1β, IL-6, iNOS, and COX2 on DSS-induced colitis. Notably, DSS inhibited the proliferation and promoted the apoptosis of intestinal epithelial cells, thereby damaging the integrity of the intestinal epithelial barrier, whereas l-theanine also played a protective role by attenuating these deteriorated effects. It was also observed that l-theanine treatment downregulated the levels of p-p65, p65, p-p53, p53, and p-AKT protein expression in acute DSS-induced colitis, which showed the protective function of l-theanine, mainly via the NF-κB signaling pathway. Furthermore, the results of lipid analysis and transcriptome analysis show that l-theanine reversed transcriptional profiles and lipid profiles of colitis models, mainly via the inflammatory reactivity-related pathway. Interestingly, the correlation analysis between transcriptional profiles and lipid profiles showed that inflammatory response-related genes were almost significantly correlated with differential lipid metabolites. In summary, l-theanine plays a protective role in DSS-induced colitis via downregulating the NF-κB signaling pathway and regulating lipid metabolism disorders.

Celecoxib Colorectal Bioavailability and Chemopreventive Response in Patients with Familial Adenomatous Polyposis

Why celecoxib exerts chemopreventive activity in only some familial adenomatous polyposis (FAP) patients remains poorly understood. We conducted a phase II clinical study to identify potential predictive biomarkers for celecoxib chemopreventive activity in FAP. Twenty-seven patients with FAP completed a 6-month oral course of 400 mg of celecoxib twice a day; they underwent colonoscopies before and after celecoxib treatment to assess colorectal polyp tumor burden and to obtain normal and polyp colorectal biopsies to measure celecoxib, 13-S-hydroxyoctadecadienoic acid (13-HODE), 15-HETE, 12-HETE, and LTB4 levels by LC/MS-MS. Celecoxib levels in sera from those patients were also measured before treatment and after 2, 4, and 6 months of treatment. Nineteen of the 27 patients experienced a response to celecoxib, with a ≥ 28% reduction of colonic polyp burden on the basis of a reproducible quantitative assessment of colonoscopy results. Celecoxib levels were significantly lower in polyp tissues than in normal colorectal tissues. Celecoxib levels in sera and normal colorectal tissues were correlated in patients who experienced a response to celecoxib but not in those who did not. Among the measured lipoxygenase products, only 13-HODE levels were significantly lower in polyp tissues than in normal tissues. Our findings demonstrate the differential bioavailability of celecoxib between normal and polyp tissues and its potential effects on clinical response in patients with FAP. PREVENTION RELEVANCE: This study evaluated potential predictive biomarkers for celecoxib chemopreventive activity in patients with FAP. Our findings demonstrated the differential bioavailability of celecoxib between normal and polyp tissues and its potential effects on clinical chemopreventive response in patients with FAP.

Improved quantification of lipid mediators in plasma and tissues by liquid chromatography tandem mass spectrometry demonstrates mouse strain specific differences

A liquid chromatography tandem mass spectrometry-based method for the quantitation of 39 lipid mediators in four sample types and in two mouse strains is described. The method builds upon existing methodologies for analysis of lipid mediators by A) utilizing a bead homogenization step for tissue samples; this eliminates the need for homogenization glassware and improves homogenization consistency, B) optimizing the isolation and purification of lipid mediators with polymeric reverse phase SPE columns with lower sorbent masses; this results in lower solvent elution volumes without loss of recovery and C) utilizing an on-column enrichment method to improve analyte focusing before chromatographic separation. The method is linear from 0.25-250 pg on column for low level lipid mediators and from 5-5000 pg on column for high level lipid mediators. The addition of a methyl formate elution step to a previously published method dramatically improved precision and recovery for the cysteinyl leukotrienes. Accuracy and precision for 4 different sample types including human plasma, mouse lung, mouse spleen and mouse liver is demonstrated. Liver samples had extremely high levels of a tentatively identified bile acid which interfered with quantitation of resolvin E1, 11B-prostaglandin F2a and thromboxane A2. Results from 2 different tissue sources from untreated mice (C57BL/6 versus BALB/c) showed dramatically different concentrations of lipid mediators.

Metabolomics analysis of lipid metabolizing enzyme activity

Lipids exert key structural, metabolic, and signaling functions in cells. Lipid diversity found in cells and tissues is regulated principally by metabolic enzymes whose activity is modulated posttranslationally to shape head group and fatty acyl composition of membrane lipids. Methodologies capable of monitoring in vivo changes in the lipidome are needed to assign substrate specificity of metabolic enzymes, which represents a key step toward understanding structure-function of lipids in living systems. The resulting lipid annotations also serve as important biomarkers for understanding mode of action for pharmacological agents targeting metabolic enzymes in cells and animal models. In this chapter, we describe a general metabolomics workflow to complement (chemo)proteomic efforts to modulate lipid pathways for basic science and translational applications.

Resveratrol inhibits obesity-associated adipose tissue dysfunction and tumor growth in a mouse model of postmenopausal claudin-low breast cancer

Adipose tissue dysregulation, a hallmark of obesity, contributes to a chronic state of low-grade inflammation and is associated with increased risk and progression of several breast cancer subtypes, including claudin-low breast tumors. Unfortunately, mechanistic targets for breaking the links between obesity-associated adipose tissue dysfunction, inflammation, and claudin-low breast cancer growth have not been elucidated. Ovariectomized female C57BL/6 mice were randomized (n = 15/group) to receive a control diet, a diet-induced obesity (DIO) diet, or a DIO + resveratrol (0.5% wt/wt) diet. Mice consumed these diets ad libitum throughout study and after 6 weeks were orthotopically injected with M-Wnt murine mammary tumor cells, a model of estrogen receptor (ER)-negative claudin-low breast cancer. Compared with controls, DIO mice displayed adipose dysregulation and metabolic perturbations including increased mammary adipocyte size, cyclooxygenase-2 (COX-2) expression, inflammatory eicosanoid levels, macrophage infiltration, and prevalence of crown-like structures (CLS). DIO mice (relative to controls) also had increased systemic inflammatory cytokines and decreased adipocyte expression of peroxisome proliferator-activated receptor gamma (PPARγ) and other adipogenesis-regulating genes. Supplementing the DIO diet with resveratrol prevented obesity-associated increases in mammary tumor growth, mammary adipocyte hypertrophy, COX-2 expression, macrophage infiltration, CLS prevalence, and serum cytokines. Resveratrol also offset the obesity-associated downregulation of adipocyte PPARγ and other adipogenesis genes in DIO mice. Our findings suggest that resveratrol may inhibit obesity-associated inflammation and claudin-low breast cancer growth by inhibiting adipocyte hypertrophy and associated adipose tissue dysregulation that typically accompanies obesity.

The EP3 receptor regulates water excretion in response to high salt intake

The mechanisms by which prostanoids contribute to the maintenance of whole body water homeostasis are complex and not fully understood. The present study demonstrates that an EP3-dependent feedback mechanism contributes to the regulation of water homeostasis under high-salt conditions. Rats on a normal diet and tap water were placed in metabolic cages and given either sulprostone (20 μg·kg^-1·day^-1) or vehicle for 3 days to activate EP3 receptors in the thick ascending limb (TAL). Treatment was continued for another 3 days in rats given either 1% NaCl in the drinking water or tap water. Sulprostone decreased expression of cyclooxygenase 2 (COX-2) expression by ∼75% in TAL tubules from rats given 1% NaCl concomitant with a ∼60% inhibition of COX-2-dependent PGE₂ levels in the kidney. Urine volume increased after ingestion of 1% NaCl but was reduced ∼40% by sulprostone. In contrast, the highly selective EP3 receptor antagonist L-798106 (100 μg·kg^-1·day^-1), which increased COX-2 expression and renal PGE₂ production, increased urine volume in rats given 1% NaCl. Sulprostone increased expression of aquaporin-2 (AQP2) in the inner medullary collecting duct plasma membrane in association with an increase in phosphorylation at Ser269 and decrease in Ser261 phosphorylation; antagonism of EP3 with L-798106 reduced AQP2 expression. Thus, although acute activation of EP3 by PGE₂ in the TAL and collecting duct inhibits the Na-K-2Cl cotransporter and AQP2 activity, respectively, chronic activation of EP3 in vivo limits the extent of COX-2-derived PGE₂ synthesis, thereby mitigating the inhibitory effects of PGE₂ on these transporters and decreasing urine volume.

A New Model to Study the Role of Arachidonic Acid in Colon Cancer Pathophysiology

A significant increase in cyclooxygenase 2 (COX2) gene expression has been shown to promote cylcooxygenase-dependent colon cancer development. Controversy associated with the role of COX2 inhibitors indicates that additional work is needed to elucidate the effects of arachidonic acid (AA)-derived (cyclooxygenase and lipoxygenase) eicosanoids in cancer initiation, progression, and metastasis. We have recently developed a novel Fads1 knockout mouse model that allows for the investigation of AA-dependent eicosanoid deficiency without the complication of essential fatty acid deficiency. Interestingly, the survival rate of Fads1-null mice is severely compromised after 2 months on a semi-purified AA-free diet, which precludes long-term chemoprevention studies. Therefore, in this study, dietary AA levels were titrated to determine the minimal level required for survival, while maintaining a distinct AA-deficient phenotype. Null mice supplemented with AA (0.1%, 0.4%, 0.6%, 2.0%, w/w) in the diet exhibited a dose-dependent increase (P < 0.05) in AA, PGE2, 6-keto PGF1α, TXB2, and EdU-positive proliferative cells in the colon. In subsequent experiments, null mice supplemented with 0.6% AA diet were injected with a colon-specific carcinogen (azoxymethane) in order to assess cancer susceptibility. Null mice exhibited significantly (P < 0.05) reduced levels/multiplicity of aberrant crypt foci (ACF) as compared with wild-type sibling littermate control mice. These data indicate that (i) basal/minimal dietary AA supplementation (0.6%) expands the utility of the Fads1-null mouse model for long-term cancer prevention studies and (ii) that AA content in the colonic epithelium modulates colon cancer risk. Cancer Prev Res; 9(9); 750-7. ©2016 AACR.

A Sucrose-Enriched Diet Promotes Tumorigenesis in Mammary Gland in Part through the 12-Lipoxygenase Pathway

Epidemiologic studies have shown that dietary sugar intake has a significant impact on the development of breast cancer. One proposed mechanism for how sugar impacts cancer development involves inflammation. In the current study, we investigated the impact of dietary sugar on mammary gland tumor development in multiple mouse models, along with mechanisms that may be involved. We found that sucrose intake in mice comparable with levels of Western diets led to increased tumor growth and metastasis, when compared with a nonsugar starch diet. This effect was ascribed in part to increased expression of 12-lipoxygenase (12-LOX) and its arachidonate metabolite 12-hydroxy-5Z,8Z,10E,14Z-eicosatetraenoic acid (12-HETE). We determined that fructose derived from the sucrose was responsible for facilitating lung metastasis and 12-HETE production in breast tumors. Overall, our data suggested that dietary sugar induces 12-LOX signaling to increase risks of breast cancer development and metastasis.

Development and application of a comprehensive lipidomic analysis to investigate Tripterygium wilfordii-induced liver injury

Lipid metabolic pathways play pivotal roles in liver function, and disturbances of these pathways are associated with various diseases. Thus, comprehensive characterization and measurement of lipid metabolites are essential to deciphering the contributions of lipid network metabolism to diseases or its responses to drug intervention. Here, we report an integrated lipidomic analysis for the comprehensive detection of lipid metabolites. To facilitate the characterization of untargeted lipids through fragmentation analysis, nine formulas were proposed to identify the fatty acid composition of lipids from complex MS (n) spectrum information. By these formulas, the co-eluted isomeric compounds could be distinguished. In total, 250 lipids were detected and characterized, including diacylglycerols, triacylglycerols, glycerophosphoethanolamines, glycerophosphocholines, glycerophosphoserines, glycerophosphoglycerols, glycerophosphoinositols, cardiolipins, ceramides, and sphingomyelins. Integrated with the targeted lipidomics, a total of 27 inflammatory oxylipins were also measured. To evaluate the aberrant lipid metabolism involved in liver injury induced by Tripterygium wilfordii, lipid network metabolism was further investigated. Results indicated that energy lipid modification, membrane remodeling, potential signaling lipid alterations, and abnormal inflammation response were associated with injury. Because of the important roles of lipids in liver metabolism, this new method is expected to be useful in analyzing other lipid metabolism diseases.

Pilot clinical study of the effects of ginger root extract on eicosanoids in colonic mucosa of subjects at increased risk for colorectal cancer

Colorectal cancer (CRC) remains a significant cause of mortality. Inhibitors of cyclooxygenase (COX) and thus prostaglandin E2, are promising CRC preventives, but have significant toxicities. Ginger has been shown to inhibit COX, to decrease the incidence and multiplicity of adenomas, and decrease PGE2 concentrations in subjects at normal risk for CRC. This study was conducted to determine the effects of 2.0 g/d of ginger given orally on the levels of PGE2, leukotriene B4 (LTB4), 13-hydroxy-octadecadienoic acids, and 5-, 12-, & 15-hydroxyeicosatetraenoic acid, in the colonic mucosa of subjects at increased risk for CRC. We randomized 20 subjects to 2.0 g/d ginger or placebo for 28 d. At baseline and Day 28, a flexible sigmoidoscopy was used to obtain colon biopsies. A liquid chromatography mass spectrometry method was used to determine eicosanoid levels in the biopsies, and levels were expressed per amount of protein or free arachidonic acid (AA). There was a significant decrease in AA between baseline and Day 28 (P = 0.05) and significant increase in LTB4 (P = 0.04) when normalized to protein, in subjects treated with ginger versus placebo. No other changes in eicosanoids were observed. There was no difference between the groups in total adverse events (AE; P = 0.06). Ginger lacks the ability to decrease eicosanoid levels in people at increased risk for CRC. Ginger did appear to be both tolerable and safe; and could have chemopreventive effects through other mechanisms. Further investigation should focus on other markers of CRC risk in those at increased CRC risk.

Omega-3-Acid Ethyl Esters Block the Protumorigenic Effects of Obesity in Mouse Models of Postmenopausal Basal-like and Claudin-Low Breast Cancer

Obesity induces chronic inflammation and is an established risk and progression factor for triple-negative breast cancers, including basal-like (BL) and claudin-low (CL) subtypes. We tested the effects of dietary supplementation with ethyl esters of the marine-derived anti-inflammatory omega-3 fatty acids eicosapentaenoic and docosahexaenoic acid (EPA+DHA; Lovaza) on growth of murine BL and CL mammary tumors. Female ovariectomized C57BL/6 mice were fed a control diet or a diet-induced obesity (DIO) diet with or without EPA+DHA (0.025%, resulting in blood levels of EPA and DHA comparable with women taking Lovaza 4 g/d) for 6 weeks. All mice were then orthotopically injected with Wnt-1 cells (a BL tumor cell suspension derived from MMTV-Wnt-1 transgenic mouse mammary tumors) or M-Wnt cells (a CL tumor cell line cloned from the Wnt-1 tumor cell suspension). Mice were killed when tumors were 1 cm in diameter. EPA+DHA supplementation did not significantly affect Wnt-1 or M-Wnt mammary tumor growth in normoweight control mice. However, EPA+DHA supplementation in DIO mice reduced growth of Wnt-1 and M-Wnt tumors; reduced leptin:adiponectin ratio and proinflammatory eicosanoids in the serum; improved insulin sensitivity; and decreased tumoral expression of COX-2 and phospho-p65. Thus, EPA+DHA supplementation in mouse models of postmenopausal BL and CL breast cancer offsets many of the protumorigenic effects of obesity. These preclinical findings, in combination with results from parallel biomarker studies in women, suggest that EPA+DHA supplementation may reduce the burden of BL and CL breast cancer in obese women.

Simultaneous quantification of leukotrienes and hydroxyeicosatetraenoic acids in cell culture medium using liquid chromatography/tandem mass spectrometry

Leukotrienes (LTs) and hydroxyeicosatetraenoic acids (HETEs) are important bioactive lipid mediators that participate in various pathophysiological processes. To advance understanding of the mechanisms that regulate these mediators in physiological and pathological processes, an analytical method using liquid chromatography/tandem mass spectrometry for the simultaneous quantification of LTB4, LTC4, LTD4, LTE4, 5-HETE, 8-HETE, 12-HETE and 15-HETE in cell culture media was developed. A Supel™-Select HLB solid-phase extraction cartridge was used for sample preparation. The compounds were separated on a C18 column using gradient elution with acetonitrile-water-formic acid (20:80:0.1, v/v/v) and acetonitrile-formic acid (100:0.1, v/v). The calibration curves of LTB4, LTD4, LTE4 and HETEs were linear in the range of 0.025-10 ng/mL, and the calibration curve of LTC4 was linear in the range of 0.25-10 ng/mL. Validation assessment showed that the method was highly reliable with good accuracy and precision. The stability of LTs and HETEs was also investigated. Using the developed method, we measured LTs and HETEs in the culture supernatant of the human mast cell line HMC-1. The present method could facilitate investigations of the mechanisms that regulate the production, release and signaling of LTs and HETEs.

Nano-LC-MS/MS for the quantitation of prostanoids in immune cells

Prostanoids, derivatives of arachidonic acid, are involved in inflammation and immune reactions. To understand the role of prostanoids produced by diverse immune cells, a highly sensitive quantitation method for prostaglandin E2 (PGE2), prostaglandin D2 (PGD2), 6-keto prostaglandin F1α (6-keto PGF1α), prostaglandin F2α (PGF2α), and thromboxane B2 (TXB2) by means of nano-liquid chromatography-tandem mass spectrometry has been developed. It was validated according to the guidelines of the Food and Drug Administration (FDA) in terms of linearity, precision, accuracy, recovery, stability, and lower limit of quantitation (LLOQ). The LLOQ were 25 pg/mL in the injected solution (75 fg on column (o.c.)) for PGE2 and PGD2 and 37.5 pg/mL (112.5 fg on column) for 6-keto PGF1α, PGF2α, and TXB2, respectively. It was successfully applied to murine mast cells isolated from paws after zymosan injection and to CD4(+) and CD8(+) T lymphocytes from blood of sensitized versus non-sensitized mice in context of a delayed type hypersensitivity model. About 5,000 (T cells) to 40,000 (mast cells) cells were sufficient for quantitation. In the mast cells, the production of PGE2 increased at a significantly higher extent than the synthesis of the other prostanoids. The T lymphocytes did not show any difference in prostanoid production, no matter whether they were obtained from sensitized mice or non-sensitized mice.

Ultrahigh-performance liquid chromatography/tandem mass spectrometry method for evaluating enzyme activity and screening inhibitors of cyclooxygenase-2

RATIONALE

Prostaglandin E2 is an important biomarker in many biological systems. The development of sensitive and reliable analytical methods for monitoring PGE2 contents in various samples is of great interest. Here we developed an improved method for evaluating the enzyme activity and screening COX-2 inhibitors using ultrahigh-performance liquid chromatography/tandem mass spectrometry (UPLC/MS/MS) combined with PGE2 derivatization.

METHODS

Girard's reagent-T was used as the derivatization reagent and the reaction conditions were optimized. The established method was performed to screen the COX-2 inhibitors from effective constituents of herbs and detect the concentration of PGE2 in biological tissue samples (liver and kidney). The IC50 values of celecoxib, rofecoxib, sinomenine, bulleyaconitine A, tetrandrine, fangchinoline, berberine hydrochloride and sophocarpidine towards COX-2 were determined.

RESULTS

This method improves the quantitative ability for PGE2 , including the linearly dependent coefficient, linearity range and limit of detection. After derivatization, the derivatized PGE2 could be detected in positive ion mode of electrospray ionization (ESI), which improves the detection sensitivity 10-fold compared to that of the direct detection of underivatized PGE2 in negative ESI mode. Besides the positive control, sinomenine (IC50 =113 μM) and bulleyaconitine A (IC50=53 μM) were found to be potent COX-2 inhibitors.

CONCLUSIONS

All the results indicate that the present derivatization quantification method of PGE2 could be used as the detection method of COX-2 enzyme activity and as the screening method for COX-2 inhibitors.

PGE(2) EP(3) receptor downregulates COX-2 expression in the medullary thick ascending limb induced by hypertonic NaCl

We tested the hypothesis that inhibition of EP3 receptors enhances cyclooxygenase (COX)-2 expression in the thick ascending limb (TAL) induced by hypertonic stimuli. COX-2 protein expression in the outer medulla increased approximately twofold in mice given free access to 1% NaCl in the drinking water for 3 days. The increase was associated with an approximate threefold elevation in COX-2 mRNA accumulation and an increase in PGE2 production by isolated medullary (m)TAL tubules from 77.3 ± 8.4 to 165.7 ± 10.8 pg/mg protein. Moreover, administration of NS-398 abolished the increase in PGE2 production induced by 1% NaCl. EP3 receptor mRNA levels also increased approximately twofold in the outer medulla of mice that ingested 1% NaCl. The selective EP3 receptor antagonist L-798106 increased COX-2 mRNA by twofold in mTAL tubules, and the elevation in COX-2 protein induced by 1% NaCl increased an additional 50% in mice given L-798106. COX-2 mRNA in primary mTAL cells increased twofold in response to media made hypertonic by the addition of NaCl (400 mosmol/kg H2O). L-798106 increased COX-2 mRNA twofold in isotonic media and fourfold in cells exposed to 400 mosmol/kg H2O. PGE2 production by mTAL cells increased from 79.3 ± 4.6 to 286.7 ± 6.3 pg/mg protein after challenge with 400 mosmol/kg H2O and was inhibited in cells transiently transfected with a lentivirus short hairpin RNA construct targeting exon 5 of COX-2 to silence COX-2. Collectively, the data suggest that local hypertonicity in the mTAL is associated with an increase in COX-2 expression concomitant with elevated EP3 receptor expression, which limits COX-2 activity in this segment of the nephron.

Mammalian target of rapamycin complex 1 and cyclooxygenase 2 pathways cooperatively exacerbate endometrial cancer

The underlying causes of endometrial cancer (EMC) are poorly understood, and treatment options for patients with advanced stages of the disease are limited. Mutations in the phosphatase and tensin homologue gene are frequently detected in EMC. Cyclooxygenase 2 (Cox2) and mammalian target of rapamycin complex 1 (mTORC1) are known downstream targets of the phosphatase and tensin homologue protein, and their activities are up-regulated in EMC. However, it is not clear whether Cox2 and mTORC1 are crucial players in cancer progression or whether they work in parallel or cooperatively. In this study, we used a Cox2 inhibitor, celecoxib, and an mTORC1 inhibitor, rapamycin, in mouse models of EMC and in human EMC cell lines to explore the interactive roles of Cox2 and mTORC1 signaling. We found that a combined treatment with celecoxib and rapamycin markedly reduces EMC progression. We also observed that rapamycin reduces Cox2 expression, whereas celecoxib reduces mTORC1 activity. These results suggest that Cox2 and mTORC1 signaling is cross-regulated and cooperatively exacerbate EMC.

Antagonizing arachidonic acid-derived eicosanoids reduces inflammatory Th17 and Th1 cell-mediated inflammation and colitis severity

During colitis, activation of two inflammatory T cell subsets, Th17 and Th1 cells, promotes ongoing intestinal inflammatory responses. n-6 polyunsaturated fatty acid- (PUFA-) derived eicosanoids, such as prostaglandin E2 (PGE2), promote Th17 cell-mediated inflammation, while n-3 PUFA antagonize both Th17 and Th1 cells and suppress PGE2 levels. We utilized two genetic mouse models, which differentially antagonize PGE2 levels, to examine the effect on Th17 cells and disease outcomes in trinitrobenzene sulfonic acid- (TNBS-) induced colitis. Fat-1 mice contain the ω3 desaturase gene from C. elegans and synthesize n-3 PUFA de novo, thereby reducing the biosynthesis of n-6 PUFA-derived eicosanoids. In contrast, Fads1 Null mice contain a disrupted Δ5 desaturase gene and produce lower levels of n-6 PUFA-derived eicosanoids. Compared to Wt littermates, Fat-1 and Fads1 Null mice exhibited a similar colitic phenotype characterized by reduced colonic mucosal inflammatory eicosanoid levels and mRNA expression of Th17 cell markers (IL-17A, RORγτ, and IL-23), decreased percentages of Th17 cells and, improved colon injury scores (P ≤ 0.05). Thus, during colitis, similar outcomes were obtained in two genetically distinct models, both of which antagonize PGE2 levels via different mechanisms. Our data highlight the critical impact of n-6 PUFA-derived eicosanoids in the promotion of Th17 cell-mediated colonic inflammation.

Prostaglandin E3 metabolism and cancer

The anticancer activity of n-3 fatty acids, especially those derived from fish, such as eicosapentaenoic acid (EPA) and docosahexaenoic acid) (DHA), has been studied for centuries. While there is a growing body of evidence that EPA and DHA may influence cancer initiation and development through targeting multiple events of tumor development, the underlying mechanisms responsible for these activities are still not fully understood. A number of studies have suggested that the anticancer activities of EPA and DHA are associated with their effects on eicosanoid metabolism by which they inhibit prostaglandin E2 (PGE2) production. In contrast to DHA, EPA can function as a substrate for cyclooxygenases (COXs) to synthesize unique 3-series prostaglandin compounds, especially PGE3. With advance technology in mass spectrometry, there is renewed interest in studying the role of PGE3 in EPA elicited anti-proliferative activity in various cancers, with some promising results. Here, we summarize the regulation of PGE3 synthesis in cancer cells and its role in EPA elicited anticancer activity. The development of PGE3 and its metabolites as potential biomarkers for future clinical evaluation of EPA and fish oil in cancer care is discussed.

Analysis, physiological and clinical significance of 12-HETE: a neglected platelet-derived 12-lipoxygenase product

While the importance of cyclooxygenase (COX) in platelet function has been amply elucidated, the identification of the role of 12-lipoxygenase (12-LOX) and of its stable metabolite, 12-hydroxyeicosatretraenoic acid (12-HETE), has not been clarified as yet. Many studies have analysed the implications of 12-LOX products in different pathological disorders but the information obtained from these works is controversial. Several analytical methods have been developed over the years to simultaneously detect eicosanoids, and specifically 12-HETE, in different biological matrices, essentially enzyme-linked immunosorbent assays (ELISA), radioimmunoassays (RIA), high performance liquid chromatography (HPLC) and mass spectrometry coupled with both gas and liquid chromatography methods (GC- and LC-MS). This review is aimed at summarizing the up to now known physiological and clinical features of 12-HETE together with the analytical methods used for its determination, focusing on the critical issues regarding its measurement.

Eicosanoid profiling in colon cancer: emergence of a pattern

Oxidative metabolism of polyunsaturated fatty acids has been linked to tumorigenesis in general and colonic tumorigenesis in particular. Earlier studies showed that cyclooxygenase-2 (COX-2) and 15-lipoxygenase-1 (15-LOX-1) have opposing impacts on colonic tumorigenesis: COX-2 promotes while 15-LOX-1 inhibits colonic tumorigenesis. Advances in liquid chromatography/mass spectrometry have allowed for measurement of various products of oxidative metabolism in a single colonic biopsy specimen. Studies of LOX products in preclinical models and in patients with familial adenomatous polyposis and sporadic colorectal tumorigenesis indicate that LOX pathways are shifted during colonic tumorigenesis and that the main shift is downregulation of 15-LOX-1. This shift occurs during the polyp formation stage and thus offers the opportunity to modulate tumorigenesis early by correcting 15-LOX-1 downregulation.

Changes in cancer cell metabolism revealed by direct sample analysis with MALDI mass spectrometry

Biomarker discovery using mass spectrometry (MS) has recently seen a significant increase in applications, mainly driven by the rapidly advancing field of metabolomics. Instrumental and data handling advancements have allowed for untargeted metabolite analyses which simultaneously interrogate multiple biochemical pathways to elucidate disease phenotypes and therapeutic mechanisms. Although most MS-based metabolomic approaches are coupled with liquid chromatography, a few recently published studies used matrix-assisted laser desorption (MALDI), allowing for rapid and direct sample analysis with minimal sample preparation. We and others have reported that prostaglandin E₃ (PGE₃), derived from COX-2 metabolism of the omega-3 fatty acid eicosapentaenoic acid (EPA), inhibited the proliferation of human lung, colon and pancreatic cancer cells. However, how PGE₃ metabolism is regulated in cancer cells, particularly human non-small cell lung cancer (NSCLC) cells, is not fully understood. Here, we successfully used MALDI to identify differences in lipid metabolism between two human non-small-cell lung cancer (NSCLC) cell lines, A549 and H596, which could contribute to their differential response to EPA treatment. Analysis by MALDI-MS showed that the level of EPA incorporated into phospholipids in H596 cells was 4-fold higher than A549 cells. Intriguingly, H596 cells produced much less PGE₃ than A549 cells even though the expression of COX-2 was similar in these two cell lines. This appears to be due to the relatively lower expression of cytosolic phospholipase A₂ (cPLA₂) in H596 cells than that of A549 cells. Additionally, the MALDI-MS approach was successfully used on tumor tissue extracts from a K-ras transgenic mouse model of lung cancer to enhance our understanding of the mechanism of action of EPA in the in vivo model. These results highlight the utility of combining a metabolomics workflow with MALDI-MS to identify the biomarkers that may regulate the metabolism of omega-3 fatty acids and ultimately affect their therapeutic potentials.

A fast one-step extraction and UPLC-MS/MS analysis for E2/D 2 series prostaglandins and isoprostanes

Prostaglandins (PG) and isoprostanes (iso-PG) may be derived through cyclooxygenase or free radical pathways and are important signaling molecules that are also robust biomarkers of oxidative stress. Their quantification is important for understanding many biological processes where PG, iso-PG, or oxidative stress are involved. One of the common methods for PG and iso-PG quantifications is LC-MS/MS that allows a highly selective, sensitive, simultaneous analysis for prostanoids without derivatization. However, the currently used LC-MS/MS methods require a multi-step extraction and a long (within an hour) LC separation to achieve simultaneous separation and analysis of the major iso-PG. The developed and validated for brain tissue analysis one-step extraction protocol and UPLC-MS/MS method significantly increases the recovery of the PG extraction up to 95 %, and allows for a much faster (within 4 min) major iso-PGE2 and -PGD2 separation with 5 times narrower chromatographic peaks as compared to previously used methods. In addition, it decreases the time and cost of analysis due to the one-step extraction approach performed in disposable centrifuge tubes. All together, this significantly increases the sensitivity, and the time and cost efficiency of the PG and iso-PG analysis.

Anticancer activity of fish oils against human lung cancer is associated with changes in formation of PGE2 and PGE3 and alteration of Akt phosphorylation

The beneficial effects of omega-3 fatty acids are believed to be due in part to selective alteration of arachidonate metabolism that involves cyclooxygenase (COX) enzymes. Here we investigated the effect of eicosapentaenoic acid (EPA) on the proliferation of human non-small cell lung cancer A549 (COX-2 over-expressing) and H1299 (COX-2 null) cells as well as their xenograft models. While EPA inhibited 50% of proliferation of A549 cells at 6.05 µM, almost 80 µM of EPA was needed to reach similar levels of inhibition of H1299 cells. The formation of prostaglandin (PG)E3 in A549 cells was almost threefold higher than that of H1299 cells when these cells were treated with EPA (25 µM). Intriguingly, when COX-2 expression was reduced by siRNA or shRNA in A549 cells, the antiproliferative activity of EPA was reduced substantially compared to that of control siRNA or shRNA transfected A549 cells. In line with this, dietary menhaden oil significantly inhibited the growth of A549 tumors by reducing tumor weight by 58.8 ± 7.4%. In contrast, a similar diet did not suppress the development of H1299 xenograft. Interestingly, the ratio of PGE3 to PGE2 in A549 was about 0.16 versus only 0.06 in H1299 xenograft tissues. Furthermore, PGE2 up-regulated expression of pAkt, whereas PGE3 downregulated expression of pAkt in A549 cells. Taken together, the results of our study suggest that the ability of EPA to generate PGE3 through the COX-2 enzyme might be critical for EPA-mediated tumor growth inhibition which is at least partly due to down-regulation of Akt phosphorylation by PGE3.

Arachidonate 5 lipoxygenase expression in papillary thyroid carcinoma promotes invasion via MMP-9 induction

Arachidonate 5-lipoxygenase (ALOX5) expression and activity has been implicated in tumor pathogenesis, yet its role in papillary thyroid carcinoma (PTC) has not been characterized. ALOX5 protein and mRNA were upregulated in PTC compared to matched, normal thyroid tissue, and ALOX5 expression correlated with invasive tumor histopathology. Evidence suggests that PTC invasion is mediated through the induction of matrix metalloproteinases (MMPs) that can degrade and remodel the extracellular matrix (ECM). A correlation between MMP-9 and ALOX5 protein expression was established by immunohistochemical analysis of PTC and normal thyroid tissues using a tissue array. Transfection of ALOX5 into a PTC cell line (BCPAP) increased MMP-9 secretion and cell invasion across an ECM barrier. The ALOX5 product, 5(S)-hydroxyeicosatetraenoic acid also increased MMP-9 protein expression by BCPAP in a dose-dependent manner. Inhibitors of MMP-9 and ALOX5 reversed ALOX5-enhanced invasion. Here we describe a new role for ALOX5 as a mediator of invasion via MMP-9 induction; this ALOX5/MMP9 pathway represents a new avenue in the search for functional biomarkers and/or potential therapeutic targets for aggressive PTC.

Short-term comparative study of the influence of fried edible oils intake on the metabolism of essential fatty acids in obese individuals

The effect of breakfast intake of fried oils containing natural antioxidants or a synthetic autooxidation inhibitor on the metabolism of essential fatty acids focused on obese individuals. Serum levels of eicosanoids were compared in individuals before and after intake of different breakfasts. Univariate descriptive analysis was used to characterise the cohort selected for this study and multivariate analysis to reveal statistical differences of normalised eicosanoids concentrations (determined by solid-phase extraction coupled to LC-MS/MS) depending on the edible oil used for breakfast preparation. The results showed that the intake of breakfast prepared with pure sunflower oil subjected to deep frying causes an effect over the eicosanoids profile that enables discrimination versus the rest of individuals. The effect was a significant increase in the concentration of hydroxyoctadecadienoic acid (HODE) metabolites, indicative markers of the intake of fried oils. The concentration of HODE metabolites was lower when the oil contained either natural antioxidants from olive-oil pomace or a synthetic autooxidation inhibitor as dimethylsiloxane. The comparison of the effect of fried sunflower oils with fried extra virgin olive oil shows the benefits associated to the consumption of the latter.

Arachidonic acid metabolism in human prostate cancer

The arachidonic acid pathway is important in the development and progression of numerous malignant diseases, including prostate cancer. To more fully evaluate the role of individual cyclooxygenases (COXs), lipoxygenases (LOXs) and their metabolites in prostate cancer, we measured mRNA and protein levels of COXs and LOXs and their arachidonate metabolites in androgen-dependent (LNCaP) and androgen-independent (PC-3 and DU145) prostate cancer cell lines, bone metastasis-derived MDA PCa 2a and MDA PCa 2b cell lines and their corresponding xenograft models, as well as core biopsy specimens of primary prostate cancer and nonneoplastic prostate tissue taken ex vivo after prostatectomy. Relatively high levels of COX-2 mRNA and its product PGE2 were observed only in PC-3 cells and their xenografts. By contrast, levels of the exogenous 12-LOX product 12-HETE were consistently higher in MDA PCa 2b and PC-3 cells and their corresponding xenograft tissues than were those in LNCaP cells. More strikingly, the mean endogenous level of 12-HETE was significantly higher in the primary prostate cancers than in the nonneoplastic prostate tissue (0.094 vs. 0.010 ng/mg protein, respectively; p=0.019). Our results suggest that LOX metabolites such as 12-HETE are critical in prostate cancer progression and that the LOX pathway may be a target for treating and preventing prostate cancer.

Characterization of an arachidonic acid-deficient (Fads1 knockout) mouse model

Arachidonic acid (20:4(Δ5,8,11,14), AA)-derived eicosanoids regulate inflammation and promote cancer development. Previous studies have targeted prostaglandin enzymes in an attempt to modulate AA metabolism. However, due to safety concerns surrounding the use of pharmaceutical agents designed to target Ptgs2 (cyclooxygenase 2) and its downstream targets, it is important to identify new targets upstream of Ptgs2. Therefore, we determined the utility of antagonizing tissue AA levels as a novel approach to suppressing AA-derived eicosanoids. Systemic disruption of the Fads1 (Δ5 desaturase) gene reciprocally altered the levels of dihomo-γ-linolenic acid (20:3(Δ8,11,14), DGLA) and AA in mouse tissues, resulting in a profound increase in 1-series-derived and a concurrent decrease in 2-series-derived prostaglandins. The lack of AA-derived eicosanoids, e.g., PGE₂ was associated with perturbed intestinal crypt proliferation, immune cell homeostasis, and a heightened sensitivity to acute inflammatory challenge. In addition, null mice failed to thrive, dying off by 12 weeks of age. Dietary supplementation with AA extended the longevity of null mice to levels comparable to wild-type mice. We propose that this new mouse model will expand our understanding of how AA and its metabolites mediate inflammation and promote malignant transformation, with the eventual goal of identifying new drug targets upstream of Ptgs2.

Phase II study of the effects of ginger root extract on eicosanoids in colon mucosa in people at normal risk for colorectal cancer

Inhibitors of COX indicate that upregulation of inflammatory eicosanoids produced by COX, and in particular prostaglandin E(2) (PGE(2)), are early events in the development of colorectal cancer (CRC). Ginger has shown downregulation of COX in vitro and decreased incidence/multiplicity of adenomas in rats. This study was conducted to determine if 2.0 g/d of ginger could decrease the levels of PGE(2), 13-hydroxy-octadecadienoic acids, and 5-, 12-, and 15-hydroxyeicosatetraenoic acid (5-, 12-, and 15-HETE), in the colon mucosa of healthy volunteers. To investigate this aim, we randomized 30 subjects to 2.0 g/d ginger or placebo for 28 days. Flexible sigmoidoscopy at baseline and day 28 was used to obtain colon biopsies. A liquid chromatography mass spectrometry method was used to determine eicosanoid levels in the biopsies, and levels were expressed per protein or per free arachidonic acid. There were no significant differences in mean percent change between baseline and day 28 for any of the eicosanoids, when normalized to protein. There was a significant decrease in mean percent change in PGE(2) (P = 0.05) and 5-HETE (P = 0.04), and a trend toward significant decreases in 12-HETE (P = 0.09) and 15-HETE (P = 0.06) normalized to free arachidonic acid. There was no difference between the groups in terms of total adverse events P = 0.55). On the basis of these results, it seems that ginger has the potential to decrease eicosanoid levels, perhaps by inhibiting their synthesis from arachidonic acid. Ginger also seemed to be tolerable and safe. Further investigation in people at high risk for CRC seems warranted.

HPLC determination of antilipoxygenase activity of a water infusion of Ligustrum vulgare L. leaves and some of its constituents

The aim of the study was a HPLC evaluation of the lipoxygenase activity inhibiting activity of a water infusion of Ligustrum vulgare L. leaves and selected isolates from it. The antiradical activity of the water infusion was determined using DPPH, ABTS and FRAP tests. Oleuropein and echinacoside concentrations in the water infusion were determined by HPLC. Water infusion, echinacoside and oleuropein were used for an antilipoxygenase activity assay using lipoxygenase isolated from rat lung cytosol fraction. Activity of 8-LOX, 12-LOX and 15-LOX were monitored through formation of 8-HETE, 12-HETE and 15-HETE, respectively. The water infusion exhibited the highest activity against all lipoxygenases, followed by oleuropein. Echinacoside was ineffective against LOXs in lower concentrations, while higher concentration showed similar inhibition on 8-LOX and 12-LOX. 15-LOX was affected more and the presence of echinacoside remarkably decreased its activity.

Identification of novel oxidized levuglandin D2 in marine red alga and mouse tissue

In animals, the product of cyclooxygenase reacting with arachidonic acid, prostaglandin(PG)H(2), can undergo spontaneous rearrangement and nonenzymatic ring cleavage to form levuglandin(LG)E(2) and LGD(2). These LGs and their isomers are highly reactive γ-ketoaldehydes that form covalent adducts with proteins, DNA, and phosphatidylethanolamine in cells. Here, we isolated a novel oxidized LGD(2) (ox-LGD(2)) from the red alga Gracilaria edulis and determined its planar structure. Additionally, ox-LGD(2) was identified in some tissues of mice and in the lysate of phorbol-12-myristate-13-acetate (PMA)-treated THP-1 cells incubated with arachidonic acid using LC-MS/MS. These results suggest that ox-LGD(2) is a common oxidized metabolite of LGD(2). In the planar structure of ox-LGD(2), H8 and H12 of LGD(2) were dehydrogenated and the C9 aldehyde was oxidized to a carboxylic acid, which formed a lactone ring with the hydrated ketone at C11. These structural differences imply that ox-LGD(2) is less reactive with amines than LGs. Therefore, ox-LGD(2) might be considered a detoxification metabolite of LGD(2).

Glutamine activates peroxisome proliferator-activated receptor-γ in intestinal epithelial cells via 15-S-HETE and 13-OXO-ODE: a novel mechanism

Glutamine possesses gut-protective effects both clinically and in the laboratory. We have shown in a rodent model of mesenteric ischemia-reperfusion that enteral glutamine increased peroxisome proliferator-activated receptor-γ (PPAR-γ) and was associated with a reduction in mucosal injury and inflammation. The mechanism by which glutamine activates PPAR-γ is unknown, and we hypothesized that it was via a ligand-dependent mechanism. Intestinal epithelial cells, IEC-6, were co-transfected with PPAR-γ response element-luciferase promoter/reporter construct. Cells were pretreated with increasing concentrations of glutamine ± GW9662 (a specific antagonist of PPAR-γ) and analyzed for PPAR-γ response element luciferase activity as an indicator of PPAR-γ activation. PPAR-γ nuclear activity was assessed by electrophoretic mobility shift assay. Cell lysates were subjected to tandem mass spectroscopy for measurement of prostaglandin and lipoxygenase metabolites. A time- and concentration-dependent increase in PPAR-γ transcriptional activity, but not mRNA or protein, was demonstrated. Activity was abrogated by the PPAR-γ inhibitor, GW9662, and changes in activity correlated with PPAR-γ nuclear binding. Glutamine, via degradation to glutamate, activated the metabolic by-products of the lipoxygenase and linoleic acid pathways, 15-S-hydroxyeicosatetraenoic acid and dehydrogenated 13-hydroxyoctaolecadienoic acid, known endogenous PPAR-γ ligands in the small bowel. This novel mechanism may explain the gut-protective effects of enteral glutamine.

Autacoid 14S,21R-dihydroxy-docosahexaenoic acid counteracts diabetic impairment of macrophage prohealing functions

Impaired macrophage functions imposed by diabetic complications and the suppressed formation of 14S,21R-dihydroxydocosa-4Z,7Z,10Z,12E,16Z,19Z-hexaenoic acid (14S,21R-diHDHA) in wounds contribute significantly to deficient wound healing in diabetics, but how are macrophage functions and 14S,21R-diHDHA formation associated? We studied 14S,21R-diHDHA generation from macrophages using liquid chromatography/mass spectrometry. The role in macrophage-mediated wound healing functions was determined using a murine splinted excisional wound healing model and in vitro assays. 14S,21R-diHDHA acts as a macrophage-generated autacoid, and its attenuated formation in macrophages of diabetic db/db mice was accompanied by impairment of macrophage prohealing functions. 14S,21R-diHDHA restored db/db macrophage-impaired prohealing functions by promoting wound re-epithelialization, formulation of granulation tissue, and vascularization. Additionally, 12/15-lipoxygenase-deficient macrophages, which are unable to produce 14S,21R-diHDHA, exhibited impaired prohealing functions, which also were restored by 14S,21R-diHDHA treatment. The molecular mechanism for 14S,21R-diHDHA-induced recovery of impaired prohealing functions of db/db macrophages involves enhancing their secretion of vascular endothelial growth factor and platelet-derived growth factor BB, decreasing hyperglycemia-induced generation of reactive oxygen species, and increasing IL-10 expression under inflammatory stimulation. Taken together, these results indicate that deficiency of 14S,21R-diHDHA formation by diabetic macrophages contributes to their impaired prohealing functions. Our findings provide mechanistic insights into wound healing in diabetics and suggest the possibility of using autologous macrophages/monocytes, treated with 14S,21R-diHDHA, or related compounds, to promote diabetes-impaired wound healing.

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.

Phase IIa clinical trial of curcumin for the prevention of colorectal neoplasia

Curcumin is derived from the spice tumeric and has antiinflammatory and antineoplastic effects in vitro and in animal models, including preventing aberrant crypt foci (ACF) and adenomas in murine models of colorectal carcinogenesis. Inhibiting the production of the procarcinogenic eicosanoids prostaglandin E₂ (PGE₂) and 5-hydroxyeicosatetraenoic acid (5-HETE) can suppress carcinogenesis in rodents. Curcumin reduces mucosal concentrations of PGE₂ (via inhibition of cyclooxygenases 1 and 2) and 5-HETE (via inhibition of 5-lipoxygenase) in rats. Although preclinical data support curcumin activity in many sites, the poor bioavailability reported for this agent supports its use in the colorectum. We assessed the effects of oral curcumin (2 g or 4 g per day for 30 days) on PGE₂ within ACF (primary endpoint), 5-HETE, ACF number, and proliferation in a nonrandomized, open-label clinical trial in 44 eligible smokers with eight or more ACF on screening colonoscopy. We assessed pre- and posttreatment concentrations of PGE₂ and 5-HETE by liquid chromatography tandem mass spectroscopy in ACF and normal-tissue biopsies; ACF number via rectal endoscopy; proliferation by Ki-67 immunohistochemistry; and curcumin concentrations by high-performance liquid chromatography in serum and rectal mucosal samples. Forty-one subjects completed the study. Neither dose of curcumin reduced PGE₂ or 5-HETE within ACF or normal mucosa or reduced Ki-67 in normal mucosa. A significant 40% reduction in ACF number occurred with the 4-g dose (P < 0.005), whereas ACF were not reduced in the 2-g group. The ACF reduction in the 4-g group was associated with a significant, five-fold increase in posttreatment plasma curcumin/conjugate levels (versus pretreatment; P = 0.009). Curcumin was well tolerated at both 2 g and 4 g. Our data suggest that curcumin can decrease ACF number, and this is potentially mediated by curcumin conjugates delivered systemically.

Identification of a cyclooxygenase gene from the red alga Gracilaria vermiculophylla and bioconversion of arachidonic acid to PGF(2α) in engineered Escherichia coli

Prostaglandins (PGs) are important local messenger molecules in many tissues and organs of animals including human. For applications in medicine and animal care, PGs are mostly purified from animal tissues or chemically synthesized. To generate a clean, reliable, and inexpensive source for PGs, we have now engineered expression of a suitable cyclooxygenase gene in Escherichia coli and achieved production levels of up to 2.7 mg l(-1) PGF(2α). The cyclooxygenase gene cloned from the red alga Gracilaria vermiculophylla appears to be fully functional without any eukaryotic modifications in E. coli. A crude extract of the recombinant E. coli cells is able to convert in vitro the substrate arachidonic acid (AA) to PGF(2α). Furthermore, these E. coli cells produced PGF(2α) in a medium supplemented with AA and secreted the PGF(2α) product. To our knowledge, this is the first report of the functional expression of a cyclooxygenase gene and concomitant production of PGF(2α) in E. coli. The successful microbial synthesis of PGs with reliable yields promises a novel pharmaceutical tool to produce PGF(2α) at significantly reduced prices and greater purity.

Ultra-pressure liquid chromatography/tandem mass spectrometry targeted profiling of arachidonic acid and eicosanoids in human colorectal cancer

Cumulative evidence shows that eicosanoids such as prostaglandins, leukotrienes, thromboxanes and hydroxy eicosatetraenoic acids play an important role in associating inflammation with human colorectal cancer (CRC). In this study an ultra-pressure liquid chromatography/tandem mass spectrometry (UPLC/MS/MS) method was developed and validated for the targeted profiling of eight relevant eicosanoids and the major metabolic precursor, arachidonic acid (AA), in human colon. Multiple reaction monitoring (MRM) experiments were performed in negative electrospray ionization mode. The metabolites were separated using a C(18) column consisting of 1.7 µm ethylene-bridged hybrid particles (100 × 2.1 mm i.d.) and gradient elution (50 to 95% of solvent B) with a mobile phase comprising water (0.1% formic acid) [solvent A] and acetonitrile (0.1% formic acid) [solvent B] at a flow rate of 0.4 mL/min. The analysis time for each sample was 5.5 min. Our UPLC/MS/MS method demonstrated satisfactory validation results in terms of selectivity, sensitivity, matrix effect, linearity, extraction efficiency, intra- and inter-day precision, accuracy and autosampler stability. The method was applied for the clinical profiling of matched pairs of cancerous and normal colon mucosae obtained from eight colorectal cancer patients. Endogenous levels of AA and selected eicosanoids such as prostaglandin E(2) (PGE(2)), prostacyclin (PGI(2)) [assayed as its stable hydrolytic product 6-keto-prostaglandin(1α) (6-k PGF(1α))] and 12-hydroxy-5Z,8Z,10E,14Z-eicosatetraenoic acid (12-HETE) were found to be significantly different (p <0.05; paired t-test) between cancerous and normal mucosae.

Ibuprofen bioconcentration and prostaglandin E2 levels in the bluntnose minnow Pimephales notatus

Prostanoids are oxygenated derivatives of arachidonic acid with a wide range of physiological effects in vertebrates including modulation of inflammation and innate immune responses. Nonsteroidal anti-inflammatory drugs (NSAIDs) act through inhibition of cyclooxygenase (COX) conversion of arachidonic acid to prostanoids. In order to better understand the potential of environmental NSAIDS for interruption of normal levels of COX products in fishes, we developed an LC/MS/MS-based approach for tissue analysis of 7 prostanoids. Initial studies examining muscle, gut and gill demonstrated that prostaglandin E2 (PGE2) was the most abundant of the measured prostanoids in all tissues and that gill tissue had the highest and most consistent concentrations of PGE2. After short-term 48-h laboratory exposures to nominal concentrations of 5, 25, 50 and 100μg/L ibuprofen, 50μg/L and 100μg/L exposure concentrations resulted in significant reduction of gill tissue PGE2 concentration by approximately 30% and 80% respectively. The lower exposures did not result in significant reductions when compared to unexposed controls. Measured tissue concentrations of ibuprofen indicated that this NSAID had little potential for bioconcentration (BCF=1.3) and the IC(50) of ibuprofen for inhibition of PGE2 production in gill tissue was estimated to be 0.4μM.

Obesity is associated with inflammation and elevated aromatase expression in the mouse mammary gland

Elevated circulating estrogen levels are associated with increased risk of breast cancer in obese postmenopausal women. Following menopause, the biosynthesis of estrogens through CYP19 (aromatase)-mediated metabolism of androgen precursors occurs primarily in adipose tissue, and the resulting estrogens are then secreted into the systemic circulation. The potential links between obesity, inflammation, and aromatase expression are unknown. In both dietary and genetic models of obesity, we observed necrotic adipocytes surrounded by macrophages forming crown-like structures (CLS) in the mammary glands and visceral fat. The presence of CLS was associated with activation of NF-κB and increased levels of proinflammatory mediators (TNF-α, IL-1β, Cox-2), which were paralleled by elevated levels of aromatase expression and activity in the mammary gland and visceral fat of obese mice. Analyses of the stromal-vascular and adipocyte fractions of the mammary gland suggested that macrophage-derived proinflammatory mediators induced aromatase and estrogen-dependent gene expression (PR, pS2) in adipocytes. Saturated fatty acids, which have been linked to obesity-related inflammation, stimulated NF-κB activity in macrophages leading to increased levels of TNF-α, IL-1β, and Cox-2, each of which contributed to the induction of aromatase in preadipocytes. The discovery of the obesity → inflammation → aromatase axis in the mammary gland and visceral fat and its association with CLS may provide insight into mechanisms underlying the increased risk of hormone receptor-positive breast cancer in obese postmenopausal women, the reduced efficacy of aromatase inhibitors in the treatment of breast cancer in these women, and their generally worse outcomes. The presence of CLS may be a biomarker of increased breast cancer risk or poor prognosis.