Abstract
Epoxyeicosatrienoic acids (EETs) are derived from cytochrome P450-catalyzed epoxygenation of arachidonic acid and have emerged as important mediators of numerous biological effects. The major elimination pathway for EETs is through soluble epoxide hydrolase (sEH)-catalyzed metabolism to dihydroxyeicosatrienoic acids (DHETs). Based on previous studies showing that EETs have anti-inflammatory effects, we hypothesized that chronic inhibition of sEH would attenuate a lipopolysaccharide (LPS)-induced inflammatory response in vivo. Continuous dosing of the sEH inhibitors 12-(3-adamantan-1-ylureido)-dodecanoic acid (AUDA), a polyethylene glycol ester of AUDA, and 1-adamantan-1-yl-3-(5-(2-(2-ethoxyethoxy)ethoxy)-pentyl)urea resulted in robust exposure to the inhibitor and target engagement, as evidenced by significant increases in plasma EET/DHET ratios following 6 days of inhibitor treatment. However, sEH inhibitor treatment was not associated with an attenuation of LPS-induced inflammatory gene expression in the liver, and AUDA did not protect from LPS-induced neutrophil infiltration. Furthermore, Ephx2-/-mice that lack sEH expression and have significantly increased plasma EET/DHET ratios were not protected from LPS-induced inflammatory gene expression or neutrophil accumulation in the liver. LPS did have an effect on sEH expression and function, as evident from a significant down-regulation of Ephx2 mRNA and a significant shift in plasma EET/DHET ratios 4 h after LPS treatment. In conclusion, there was no evidence that increasing EET levels in vivo could modulate an LPS-induced inflammatory response in the liver. However, LPS did have significant effects on plasma eicosanoid levels and hepatic Ephx2 expression, suggesting that in vivo EET levels are modulated in response to an inflammatory signal.
Footnotes
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This work was supported by National Institutes of Health Grant HL53994 (to D.L.K.). Partial support was provided by National Institutes of Health Grants ES02710, ES004699, and HL59699 (to B.D.H.). K.L.F. was supported in part by an American Heart Association Predoctoral Fellowship and by National Institutes of Health Grant T32 GM007175. H.-J.T. was supported by Howard Hughes Medical Institute fellowship 56005706.
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Article, publication date, and citation information can be found at http://jpet.aspetjournals.org.
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doi:10.1124/jpet.108.142398.
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ABBREVIATIONS: EET, epoxyeicosatrienoic acid; P450, cytochrome P450; sEH, soluble epoxide hydrolase; DHET, dihydroxyeicosatrienoic acid; LPS, lipopolysaccharide; NF-κB, nuclear factor-κB; iNOS, inducible nitric-oxide synthase; VCAM, vascular cellular adhesion molecule; GAPDH, glyceraldehyde-3-phosphate dehydrogenase; mEH, microsomal epoxide hydrolase; HRP, horseradish peroxidase; AUDA, 12-(3-adamantan-1-yl-ureido)-dodecanoic acid; AEPU, 1-adamantan-1-yl-3-(5-(2-(2-ethoxyethoxy)ethoxy)pentyl)urea; PEG, polyethylene glycol; PCR, polymerase chain reaction; LC/MS/MS, liquid chromatography-tandem mass spectrometry; Il, interleukin; Agp, α1-acid glycoprotein; Fbg, fibrinogen; EpOME, epoxyoctadecanoic acid; cPLA2, cytosolic phospholipase A2; Cox-2, cyclooxygenase-2; Tnf-α, tumor necrosis factor; DHOME, dihydroxyochadecanoic acid.
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↵ The online version of this article (available at http://jpet.aspetjournals.org) contains supplemental material.
- Received June 19, 2008.
- Accepted September 23, 2008.
- The American Society for Pharmacology and Experimental Therapeutics
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