Novel metabolomic method to assess the effect-based removal efficiency of advanced wastewater treatment techniques

Unprecedented levels of chemicals of anthropogenic origin are currently released into surface waters globally. Wastewater treatment plant effluent has been identified as a major source, containing a broad mixture of pharmaceuticals and consumer chemicals. Therefore, there is a need for implementation of advanced wastewater treatment techniques, such as ozonation and adsorption methods, to reduce the contamination. However, there are conflicting findings on the toxicity of treated effluent and only limited possibilities for assessing the effect-based removal efficiency (EBRE) of different treatment techniques. Here, we describe a metabolomics approach to detect perturbations in fatty acid catabolic pathways as a proxy for biological effects. Metabolites in three fatty acid pathways were analyzed in a common damselfly larva (Coenagrion hastulatum) by liquid chromatography coupled to mass spectrometry. The larvae were exposed for one week to either conventionally treated effluent (activated sludge treatment), effluent additionally treated with ozone or effluent additionally treated with biochar filtration and results were compared with those from tap water control exposure. Five lipoxygenase-derived oxylipins (9,10,13-TriHOME, 9,12,13-TriHOME, 9-HODE, 9-HOTrE, and 13-HOTrE) decreased in response to conventionally treated effluent exposure. By using an additional treatment step, oxylipin levels were restored with exception of 9,10,13-TriHOME (ozonated effluent), and 9-HOTrE and 13-HOTrE (effluent filtered with biochar). In conclusion, exposure to wastewater effluent affected fatty acid metabolite levels in damselfly larvae, and a subset of the analyzed metabolites may serve as indicators for biological effects in biota in response to effluent exposure. To that effect, our findings suggest a new metabolomics protocol for assessing EBRE.

Epoxy Fatty Acids Are Promising Targets for Treatment of Pain, Cardiovascular Disease and Other Indications Characterized by Mitochondrial Dysfunction, Endoplasmic Stress and Inflammation

Bioactive lipid mediators resulting from the metabolism of polyunsaturated fatty acids (PUFA) are controlled by many pathways that regulate the levels of these mediators and maintain homeostasis to prevent disease. PUFA metabolism is driven primarily through three pathways. Two pathways, the cyclooxygenase (COX) and lipoxygenase (LO) enzymatic pathways, form metabolites that are mostly inflammatory, while the third route of metabolism results from the oxidation by the cytochrome P450 enzymes to form hydroxylated PUFA and epoxide metabolites. These epoxygenated fatty acids (EpFA) demonstrate largely anti-inflammatory and beneficial properties, in contrast to the other metabolites formed from the degradation of PUFA. Dysregulation of these systems often leads to chronic disease. Pharmaceutical targets of disease focus on preventing the formation of inflammatory metabolites from the COX and LO pathways, while maintaining the EpFA and increasing their concentration in the body is seen as beneficial to treating and preventing disease. The soluble epoxide hydrolase (sEH) is the major route of metabolism of EpFA. Inhibiting its activity increases concentrations of beneficial EpFA, and often disease states correlate to mutations in the sEH enzyme that increase its activity and decrease the concentrations of EpFA in the body. Recent approaches to increasing EpFA include synthetic mimics that replicate biological activity of EpFA while preventing their metabolism, while other approaches focus on developing small molecule inhibitors to the sEH. Increasing EpFA concentrations in the body has demonstrated multiple beneficial effects in treating many diseases, including inflammatory and painful conditions, cardiovascular disease, neurological and disease of the central nervous system. Demonstration of efficacy in so many disease states can be explained by the fundamental mechanism that EpFA have of maintaining healthy microvasculature and preventing mitochondrial and endoplasmic reticulum stress. While there are no FDA approved methods that target the sEH or other enzymes responsible for metabolizing EpFA, current clinical efforts to test for efficacy by increasing EpFA that include inhibiting the sEH or administration of EpFA mimics that block metabolism are in progress.

Addition of Endothelin A-Receptor Blockade Spoils the Beneficial Effect of Combined Renin-Angiotensin and Soluble Epoxide Hydrolase Inhibition: Studies on the Course of Chronic Kidney Disease in 5/6 Nephrectomized Ren-2 Transgenic Hypertensive Rats

Introduction: Previous studies in Ren-2 transgenic hypertensive rats (TGR) after 5/6 renal ablation (5/6 NX) have shown that besides pharmacological blockade of the renin-angiotensin system (RAS) also increasing kidney tissue epoxyeicosatrienoic acids (EET) levels by blocking soluble epoxide hydrolase (sEH), an enzyme responsible for degradation of EETs, and endothelin type A (ETA) receptor blockade retards chronic kidney disease (CKD) progression. This prompted us to evaluate if this progression will be alleviated by the addition of sEH inhibitor and ETA receptor antagonist to the standard complex blockade of RAS (angiotensin-converting enzyme inhibitor plus angiotensin II type 1 receptor blocker) in rats with established CKD. Methods: The treatment regimens were initiated 6 weeks after 5/6 NX in TGR, and the follow-up period was 60 weeks. Results: The addition of sEH inhibition to RAS blockade improved survival rate, further reduced albuminuria and renal glomerular and kidney tubulointerstitial injury, and attenuated the decline in creatinine clearance – all this as compared with 5/6 NX TGR treated with RAS blockade alone. Addition of ETA receptor antagonist to the combined RAS and sEH blockade not only offered no additional renoprotection but, surprisingly, also abolished the beneficial effects of adding sEH inhibitor to the RAS blockade. Conclusion: These data indicate that pharmacological strategies that combine the blockade of RAS and sEH could be a novel tool to combat the progression of CKD. Any attempts to further extend this therapeutic regimen should be made with extreme caution.

Impact of the acute local inhibition of soluble epoxide hydrolase on diabetic skin microcirculatory dysfunction

The impact of the local inhibition of soluble epoxide hydrolase, which metabolizes vasodilator and anti-inflammatory epoxyeicosanoids, on diabetic skin microvascular dysfunction was assessed. In diabetic db/db mice, basal skin blood flow assessed using laser Doppler imaging was similar to that of control mice, but thermal hyperemia was markedly reduced. At 2 h after the topical administration of an aqueous gel containing the soluble epoxide hydrolase inhibitor trans-4-[4-(3-adamantan-1-yl-ureido)-cyclohexyloxy]-benzoic acid (t-AUCB: 400 mg/L), the peak concentration of t-AUCB was detected in the skin of diabetic mice, which quickly decreased thereafter. In parallel, 2 h after application of t-AUCB treatment, thermal hyperemia was increased compared to the control gel. Quantification of t-AUCB in plasma of treated animals showed no or low systemic diffusion. Furthermore, haematoxylin and eosin histological staining of skin biopsies showed that skin integrity was preserved in t-AUCB-treated mice. Finally, for pig ear skin, a surrogate for human skin, using Franz diffusion cells, we observed a continuous diffusion of t-AUCB from 2 h after application to beyond 24 h. A single topical administration of a soluble epoxide hydrolase inhibitor improves microcirculatory function in the skin of db/db mice and might represent a new therapeutic approach for preventing the development of skin complications in diabetic patients.

A permethrin metabolite is associated with adaptive immune responses in Gulf War Illness

Gulf War Illness (GWI), affecting 30% of veterans from the 1991 Gulf War (GW), is a multi-symptom illness with features similar to those of patients with autoimmune diseases. The objective of the current work is to determine if exposure to GW-related pesticides, such as permethrin (PER), activates peripheral and central nervous system (CNS) adaptive immune responses. In the current study, we focused on a PER metabolite, 3-phenoxybenzoic acid (3-PBA), as this is a common metabolite previously shown to form adducts with endogenous proteins. We observed the presence of 3-PBA and 3-PBA modified lysine of protein peptides in the brain, blood and liver of pyridostigmine bromide (PB) and  PER (PB+PER) exposed mice at acute and chronic post-exposure timepoints. We tested whether 3-PBA-haptenated albumin (3-PBA-albumin) can activate immune cells since it is known that chemically haptenated proteins can stimulate immune responses. We detected autoantibodies against 3-PBA-albumin in plasma from PB + PER exposed mice and veterans with GWI at chronic post-exposure timepoints. We also observed that in vitro treatment of blood with 3-PBA-albumin resulted in the activation of B- and T-helper lymphocytes and that these immune cells were also increased in blood of PB + PER exposed mice and veterans with GWI. These immune changes corresponded with elevated levels of infiltrating monocytes in the brain and blood of PB + PER exposed mice which coincided with alterations in the markers of blood-brain barrier disruption, brain macrophages and neuroinflammation. These studies suggest that pesticide exposure associated with GWI may have resulted in the activation of the peripheral and CNS adaptive immune responses, possibly contributing to an autoimmune-type phenotype in veterans with GWI.

Inhibition of Pancreatic Carcinoma Growth Through Enhancing ω-3 Epoxy Polyunsaturated Fatty Acid Profile by Inhibition of Soluble Epoxide Hydrolase

BACKGROUND/AIM

Cytochrome P450 epoxygenase is a major enzyme involved in the metabolism of ω-3 polyunsaturated fatty acids (PUFAs) to produce biologically active ω-3 epoxy fatty acids (ω-3 epoxides). In general, all epoxy PUFAs including ω-3 epoxides are quickly metabolized/inactivated by soluble epoxide hydrolase (sEH) to form diol products. The aims of this study were to determine the effect and mechanism of fat-1 transgene, and ω-3 PUFA combined with sEH gene knockout or inhibitor on inhibiting pancreatic cancer and the related mechanisms involved.

MATERIALS AND METHODS

PK03-mutant Kras^G12D murine pancreatic carcinoma cells were inoculated into mouse models including fat-1, sEH^-/- and C57BL/6J mice. The mice were fed with AIN-76A diet with or without ω-3 PUFA supplementation or treated with sEH inhibitor. In addition to tumor growth (tumor size and weight), cell proliferation, mutant Kras-mediated signaling, inflammatory reaction and angiogenesis were analyzed immunohisto-chemically and by western blot assay. ω-3 PUFA metabolism, particularly focusing on ω-3 epoxy fatty acids (ω-3 epoxides), was measured using a liquid chromatography with tandem mass spectrometry (LC-MS/MS) approach.

RESULTS

Significant decreases of weight and size of the PK03 pancreatic carcinoma were observed in the fat-1 transgenic mice treated with sEH inhibitor compared to those of C57BL/6J control mice fed with AIN-76A diet (weight: 0.28±0.04 g vs. 0.58±0.06 g; size: 187.0±17.5 mm³ vs. 519.3±60.6 mm³). In a separate experiment, sEH^-/- mice fed ω-3 PUFA supplement and C57BL/6J mice treated with sEH inhibitor and fed ω-3 PUFA supplement exhibited a significant reduction in the weight and size of the pancreatic carcinoma compared to C57BL/6J control mice (weight: 0.26±.26 g and 0.39±.39 g vs. 0.69±0.11 g, respectively; size: 274.2±36.2 mm³ and 296.4±99.8 mm³ vs. 612.6±117.8 mm³, respectively). Moreover, compared to the pancreatic tumors in C57BL/6J control mice, the tumors in fat-1 transgenic mice treated with sEH inhibitor showed a significant less inflammatory cell infiltrate (62.6±9.2/HPF (high power field) vs. 8.0±1.2/HPF), tumor cell proliferation (48.5±1.7% vs. 16.5±1.6%), and angiogenesis (micro-vessel density (MVD): 35.0±1.0 vs. 11.1±0.5) immunohistochemically, as well as significantly increased caspase-3 labeled apoptosis (0.44±0.06% vs. 0.69±0.06%, respectively). Using western blot approach, significant inhibition of mutant Kras-activated signals including phosphorylated Serine/threonine kinases (cRAF), Mitogen-activated protein kinase kinase (MEK), and extracellular signal-regulated kinase (ERK) were identified in pancreatic carcinoma of fat-1 transgenic mice treated with sEH inhibitor. Eicosanoic acid metabolic profiling of the serum specimens detected a significant increase of the ratios of epoxides to dihydroxy fatty acid (DiHDPE) for docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), and epoxides/dihydroxy octadecenoic acid (DiHOME) for arachidonic acid (ARA) and linoleic acid (LA), as well as a significant increase of epoxy metabolites of DHA, EPA, ARA and LA in fat-1 transgenic mice treated with a sEH inhibitor.

CONCLUSION

ω-3 epoxy products from ω-3 PUFA metabolism play a crucial role in inhibiting pancreatic cancer growth, and use of ω-3 PUFAs combined with sEH inhibition is a strategy with high potential for pancreatic cancer treatment and prevention.

Soluble Epoxide Hydrolase Inhibitor t-AUCB Promotes Murine Brown Adipogenesis: Role of PPAR Gamma and PPAR Alpha (P21-069-19)

Objectives

Brown adipose tissue has recently emerged as a novel target for obesity treatment and prevention. In contrast to the lipid storing function of white adipocytes, brown adipocytes are responsible for dissipating energy as heat, a process involving uncoupling protein 1 (UCP1). Soluble epoxide hydrolase (sEH) is a cytosolic enzyme that converts epoxy fatty acids (EpFAs) into less active diols. By stabilizing endogenous EpFAs, potent small molecule sEH inhibitors have been shown to be beneficial for many chronic diseases. Several recent papers have reported that sEH inhibitors are able to reduce diet-induced obesity, possibly by upregulating UCP1 expression. In the current study, we sought to study the mechanisms by which sEH inhibitor acts on brown preadipocytes.

Methods

The effects of a potent sEH inhibitor, trans-4-[4-(3-adamantan-1-yl-ureido)-cyclohexyloxy]-benzoic acid (t-AUCB), on murine brown adipocyte differentiation were evaluated by lipid accumulation and expression of brown adipocyte marker genes. PPAR alpha and PPAR gamma activation by t-AUCB was measured by their respective transactivation assays. The roles of PPARs were further studied by pharmacological antagonism and knockdown experiments by small RNA interference.

Results

We report that sEH expression was increased during murine brown adipocyte differentiation. t-AUCB dose-dependently promoted brown adipocyte differentiation. Moreover, we demonstrate that t-AUCB activated PPAR alpha, but not PPAR gamma. t-AUCB-induced upregulation of thermogenic gene Ucp1 and Pgc1 alpha and the general differentiation marker Fabp4 were significantly attenuated by the antagonist of PPAR alpha, GW6471. In contrast, they were only partially attenuated by the antagonist of PPAR gamma, GW9662, and specific knockdown of PPAR gamma.

Conclusions

Our findings suggest that sEH may regulate brown adipogenesis and sEH pharmacological inhibition by t-AUCB promotes brown adipogenesis, possibly through activation of PPAR alpha.

Funding Sources

The work is supported by NIH 1R15DK114790-01A1 (to LZ), R00DK100736 (to AB) and R01ES002710 (to BDH).

SUN-023 HNF4a Isoforms Regulate the Circadian Balance between Carbohydrate and Fatty Acid Metabolism in the Liver

Nuclear receptor genes often contain alternative promoters but the physiological relevance of the different promoters or the proteins they generate is largely unknown. Hepatocyte Nuclear Factor 4α (HNF4α), master regulator of hepatocyte differentiation and the most abundant nuclear receptor in the liver, is regulated by two promoters (P1 and P2). P1-HNF4α, a tumor suppressor, is the major isoform in the adult liver while P2-HNF4α is expressed in fetal liver and liver cancer: a role for P2-HNF4α in normal adult liver has not been identified. Here we show for the first time that P2-HNF4α is expressed at ZT9 and ZT21 in the normal adult liver and use P2-HNF4α-expressing exon swap mice and ‘omics approaches to demonstrate that P2-HNF4α orchestrates a distinct transcriptome and metabolome via unique chromatin and protein-protein interactions. Cytochrome P450 and sex-specific gene expression is impacted as well as carbohydrate and fatty acid metabolism. The exon swap mice exhibit subtle differences in circadian gene regulation and disruption of the clock increases expression of P2-HNF4α. They also exhibit notable differences in carbohydrate versus fatty acid metabolism with P1-HNF4α driving gluconeogenesis and P2-HNF4α driving ketogenesis. Our results also show that P2-HNF4α is required for the elevated levels of ketone bodies in female mice. Taken together, we propose that the highly conserved two-promoter structure in the Hnfa gene is designed, at least in part, to respond to the availability of food resources and maintain the balance between gluconeogenesis and ketogenesis in a circadian and sex-specific fashion. (Funding: NIH NIDDK, West Cost Metabolomics Center, NIEHS T32, USDA NIFA, CCFA, Superfund Research Program)

Development of amide-based fluorescent probes for selective measurement of carboxylesterase 1 activity in tissue extracts

Carboxylesterases are well known for their role in the metabolism of xenobiotics. However, recent studies have also implicated carboxylesterases in regulating a number of physiological processes including metabolic homeostasis and macrophage development, underlying the need to quantify them individually. Unfortunately, current methods for selectively measuring the catalytic activity of individual carboxylesterases are not sufficiently sensitive to support many biological studies. In order to develop a more sensitive and selective method to measure the activity of human carboxylesterase 1 (hCE1), we generated and tested novel substrates with a fluorescent aminopyridine leaving group. hCE1 showed at least a 10-fold higher preference for the optimized substrate 4-MOMMP than the 13 other esterases tested. Because of the high stability of 4-MOMMP and its hydrolysis product, this substrate can be used to measure esterase activity over extended incubation periods yielding a low picogram (femtomol) limit of detection. This sensitivity is comparable to current ELISA methods; however, the new assay quantifies only the catalytically active enzyme facilitating direct correlation to biological processes. The method described herein may allow hCE1 activity to be used as a biomarker for predicting drug pharmacokinetics, early detection of hepatocellular carcinoma, and other disease states where the activity of hCE1 is altered.

Abstract P430: Soluble Epoxide Hydrolase Inhibition Augments Ras Blockade Renoprotection in 5/6 Nephrectomized Ren-2 Transgenic Hypertensive Rats With Chronic Kidney Disease

Rationale and Objective: We showed recently that increasing kidney tissue epoxyeicosatrienoic acids (EETs) by blocking soluble epoxide hydrolase (sEH) and thereby blocking EETs degradation to inactive dihydroxyeicosatrienoic acids (DHETEs) substantially attenuated the progression of chronic kidney disease (CKD) in Ren-2 transgenic hypertensive rats (TGR) subjected to 5/6 renal mass reduction (5/6 NX). In this study we examined if in this model addition of sEH inhibition to the complex (dual) renin-angiotensin system (RAS) blockade would bring additional renoprotective effects in already established CKD.

Methods: TGR aged 9 weeks underwent 5/6 NX and then were left untreated for 6 weeks to develop CKD. Then dual RAS blockade : ACE inhibition (trandolapril) + angiotensin AT 1 receptor blockade (losartan) was instituted, alone or combined with sEH inhibition (c-AUCB, 3 mg/l in drinking water). During the 60 weeks’ follow-up period albuminuria and urinary creatinine excretion was repeatedly determined. The following experimental groups were investigated: ; 1) sham-operated TGR; 2) Untreated 5/6 NX TGR; 3) 5/6 NX TGR + RAS blockade ; 4) 5/6 NX TGR + RAS + sEH blockade. Sham-operated transgene-negative normotensive Hannover-Sprague Dawley (HanSD) rats served as basic controls. In separate groups renal glomerular and tubulointerstitial injury was assessed, and effects of two weeks’ treatments on systolic blood pressure (SBP, measured by telemetry) and on kidney ANG II, ANG 1-7, EETs and DHETEs levels were determined.

Results: All untreated TGR died by week 14 after 5/6 NX. RAS blockade increased the final survival rate to 23%, normalized SBP (116 ± 3 vs. 198 ± 3 mmHg, p<0.0015), reduced albuminuria (46 ± 5 vs. 102 ± 12 mg/24 h, p<0.001) and intrarenal ANG II (27 ± 8 vs. 189 ± 14 fmol/g p<0.0015) and did not alter kidney EETs/DHETEs ratio. After addition of sEH blockade kidney EETs/DHETEs ratio increased to 2.89 ± 0.42 (p<0.001 vs. 5/6 NX TGR treated with RAS blockade), the final survival rate increased to 42% and indices of renal glomerular and tubulointerstial injury improved.

Conclusion: Addition of sEH blockade to the RAS blockade brings additional renoprotective effects on the CKD progression in 5/6 NX TGR, even when applied in the advanced phase of the disease.

Abstract P425: Ras Blockade Alone or Combined With Inhibition of Soluble Epoxide Hydrolase: Effects on the Course of Congestive Heart Failure in Ren-2 Transgenic Hypertensive Rats With Aorto-caval Fistula

Rationale and Objective: We recently showed that increasing epoxyeicosatrienoic acids (EETs) in kidney by blocking soluble epoxide hydrolase (sEH), an enzyme responsible for EETs degradation, markedly attenuated the development of renal dysfunction and progression of aorto-caval (ACF)-induced congestive heart failure (CHF) in Ren-2 transgenic hypertensive rats (TGR). Therefore, in this study we examined if additional inhibition of sEH to RAS blockade could further improve the course of ACF-induced CHF in TGR.

Methods: The treatment regimens were started from one week after creation of ACF and the follow-up period was 60 weeks. RAS blockade was achieved by administration of angiotensin-converting enzyme inhibitor (ACEi, trandolapril, 3 mg/L in drinking water) and sEH was blocked using a sEH inhibitor (sEHi, c -AUCB, 3 mg/L in drinking water). The following experimental groups were investigated: 1) Sham-operated TGR; 2) Untreated ACF TGR; 3) ACF TGR + ACEi; 4) ACF TGR + ACEi + sEHi (n = 36 in each ACF group). In separate groups renal hemodynamics and excretory function were evaluated two weeks post-ACF, just before the onset the decompensated phase of CHF.

Results: After 29 weeks post-ACF, no animal survived. ACEi treatment greatly improved the survival rate (87%) at the end of study. Surprisingly, combined treatment with ACEi and sEHi worsened the rate (53%, p < 0.05). After 2 weeks post-ACF, untreated TGR group showed lower mean arterial pressure (MAP) (124 ± 3 vs. 146 ± 4 mmHg, p < 0.05), renal blood flow (7.6 ± 0.3 vs. 10.5 ± 0.3 mL.min -1 .g -1 , p < 0.05) and absolute sodium excretion (0.18 ± 0.06 vs. 1.09 ± 0.19 μmol.min -1 .g -1 , p<0.05) than sham-operated TGR group, respectively. The treatment with ACEi alone or combination treatment with sEHi did not prevent the changes in renal hemodynamics and sodium excretion.

Conclusion: We found that addition of sEHi to ACEi treatment did not provide better protection against CHF progression and the survival rate, indeed, decreased significantly. Thus, increasing bioavailability of tissue EETs in individuals with pharmacologically-induced suppression of the RAS is not a promising approach to further attenuate renal dysfunction and progression of CHF.

Development of 1-((1,4-trans)-4-Aryloxycyclohexyl)-3-arylurea Activators of Heme-Regulated Inhibitor as Selective Activators of the Eukaryotic Initiation Factor 2 Alpha (eIF2α) Phosphorylation Arm of the Integrated Endoplasmic Reticulum Stress Response

Heme-regulated inhibitor (HRI), an eukaryotic translation initiation factor 2 alpha (eIF2α) kinase, plays critical roles in cell proliferation, differentiation, adaptation to stress, and hemoglobin disorders. HRI phosphorylates eIF2α, which couples cellular signals, including endoplasmic reticulum (ER) stress, to translation. We previously identified 1,3-diarylureas and 1-((1,4-trans)-4-aryloxycyclohexyl)-3-arylureas (cHAUs) as specific activators of HRI that trigger the eIF2α phosphorylation arm of ER stress response as molecular probes for studying HRI biology and its potential as a druggable target. To develop drug-like cHAUs needed for in vivo studies, we undertook bioassay-guided structure-activity relationship studies and tested them in the surrogate eIF2α phosphorylation and cell proliferation assays. We further evaluated some of these cHAUs in endogenous eIF2α phosphorylation and in the expression of the transcription factor C/EBP homologous protein (CHOP) and its mRNA, demonstrating significantly improved solubility and/or potencies. These cHAUs are excellent candidates for lead optimization for development of investigational new drugs that potently and specifically activate HRI.

Modulation of innate immunity of patients with Alzheimer's disease by omega-3 fatty acids

The innate immune system of patients with Alzheimer's disease and mild cognitive impairment (MCI) is deregulated with highly increased or decreased transcription of inflammatory genes and consistently depressed phagocytosis of amyloid-β_1-42 (Aβ) by monocytes and macrophages. Current immune therapies target single mechanisms in the adaptive immune system but not innate immunity. Here, we summarize recent advances in therapy by ω-3, ω-6, and epoxy fatty acids; specialized proresolving mediators; and vitamin D₃ that have proven immune effects and emerging cognitive effects in patients with MCI. The hypothesis of this approach is that macrophages of normal participants, but not those of patients with Alzheimer's disease and MCI, possess effective phagocytosis for Aβ and protect homeostasis of the brain and, furthermore, that defective MCI macrophages recover phagocytic function via ω-3. Recent studies of fish-derived ω-3 supplementation in patients with MCI have shown polarization of Apoε3/ε3 patients' macrophages to an intermediate M1-M2 phenotype that is optimal for Aβ phagocytosis and the stabilization of cognitive decline. Therefore, accumulating preclinical and preliminary clinical evidence indicates that ω-3 supplementation should be tested in a randomized controlled clinical trial and that the analysis should involve the apolipoprotein E genotype and intervening conditions during trial.-Fiala, M., Kooij, G., Wagner, K., Hammock, B., Pellegrini, M. Modulation of innate immunity of patients with Alzheimer's disease by omega-3 fatty acids.

3,3',4,4',5-Pentachlorobiphenyl (PCB 126) Decreases Hepatic and Systemic Ratios of Epoxide to Diol Metabolites of Unsaturated Fatty Acids in Male Rats

Disruption of the homeostasis of oxygenated regulatory lipid mediators (oxylipins), potential markers of exposure to aryl hydrocarbon receptor (AhR) agonists, such as 3,3',4,4',5-pentachlorobiphenyl (PCB 126), is associated with a range of diseases, including nonalcoholic fatty liver disease and nonalcoholic steatohepatitis. Here we test the hypothesis that PCB 126 exposure alters the levels of oxylipins in rats. Male Sprague-Dawley rats (5-weeks old) were treated over a 3-month period every 2 weeks with intraperitoneal injections of PCB 126 in corn oil (cumulative doses of 0, 19.8, 97.8, and 390 µg/kg b.w.; 6 injections total). PCB 126 treatment caused a reduction in growth rates at the highest dose investigated, a dose-dependent decrease in thymus weights, and a dose-dependent increase in liver weights. Liver PCB 126 levels increased in a dose-dependent manner, while levels in plasma were below or close to the detection limit. The ratios of several epoxides to diol metabolites formed via the cytochrome P450 (P450) monooxygenase/soluble epoxide hydrolase (sEH) pathway from polyunsaturated fatty acids displayed a dose-dependent decrease in the liver and plasma, whereas levels of oxylipins formed by other metabolic pathways were generally not altered by PCB 126 treatment. The effects of PCB 126 on epoxide-to-diol ratios were associated with an increased CYP1A activity in liver microsomes and an increased sEH activity in liver cytosol and peroxisomes. These results suggest that oxylipins are potential biomarkers of exposure to PCB 126 and that the P450/sEH pathway is a therapeutic target for PCB 126-mediated hepatotoxicity that warrants further attention.

Abstract LB-299: Enhanced inhibitory effects on mutant KrasG12D-initiated murine pancreatic carcinoma growth in Fat-1 transgenic mice treated with soluble epoxide hydrolase inhibitor t-AUCB

Anti-carcinogenic effects of ω-3 polyunsaturated fatty acid (PUFAs) are well known; but the mechanism/s remains unclear. Of the three metabolic pathways (COX, LOX, and CYP), ω-3 PUFAs are predominantly metabolized by cyto-p450 epoxygenase/s, leading to an accumulation of ω-3 epoxy fatty acid (ω-3 epoxides), and ω-3 PUFAs are poor substrates of COX and LOX. Functional studies indicate that ω-3 epoxides are highly potential metabolites responsible for anti-inflammatory/carcinogenic actions. However, under physiologic conditions, these ω-3 epoxides are quickly inactivated by soluble epoxide hydrolase (sEH) to the diol products, and a sEH inhibitor appears crucial to stabilizing/enhancing the actions of these ω-3 epoxides. Fat1 transgenic mouse constitutively converts ω-6 to ω-3 PUFAs in all organs and are an efficient model to study ω-3 PUFAs. Herein, we have determined if a potent sEH inhibitor t-AUCB enhanced the inhibitory effect on mutant KrasG12D-initiated pancreatic cancer growth in Fat-1 mice and further determined the metabolic profile of ω-3 PUFAs, particularly on epoxide metabolites. Using an implanted mouse pancreatic carcinoma model (PK03 cell line, obtained from LSL-KrasG12D/Pdx1-Cre mice), a significant reduction of in vivo implanted PK03 pancreatic carcinoma growth was observed in Fat1 mice compared to wild type mice (Tumor volume: 355 ± 50 vs 519 ± 61 mm3, P&lt;0.05), and with t-AUCB treatment the most significant reduction of tumor volume was observed (Tumor volume: 279 ± 35 vs 519 ± 61 mm3, P&lt;0.01), but no difference for tumor volume in wild type mice with or without t-AUCB treatment (522 ± 70 vs 519 ± 61 mm3). Using LC-MS/MS metabolomics approach, modulation of the full oxylipin profile, particularly increased ratio of epoxide metabolites/its corresponded diols for ω-3 PUFAs, was observed in Fat1 mice treated with t-AUCB. Western blot and immunohistochemistry analysis revealed a significant down-regulation of Kras-activated phosphorylated-form C-Raf, MEK and Erk, as well as an up-regulation of E-cadherin; and immunohistochemistry study further demonstrated that ki-67 labeled cell proliferation and myeloperoxidase-labeled inflammatory cells (neutrophils/macrophages) were significantly reduced and Caspase-3 labeled cell apoptosis was significantly increased in pancreatic carcinoma in Fat-1 mice treated with t-AUCB. These results indicate that sEH inhibitor t-AUCB combined with ω-3 PUFAs is a highly potential and efficient approach to treat and prevent pancreatic cancer, particularly via stabilizing ω-3 epoxides. (Supported by NIH R01CA164041 and R01CA172431)

Citation Format: Jie Liao, Rong Xia, Jun Yang, Haonan Li, Dandan Xu, Xueyan Wang, Xiaoming You, Sung Hee Hwang, Bruce Hammock, Guang-Yu Yang. Enhanced inhibitory effects on mutant KrasG12D-initiated murine pancreatic carcinoma growth in Fat-1 transgenic mice treated with soluble epoxide hydrolase inhibitor t-AUCB. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr LB-299.