Inhibition of Soluble Epoxide Hydrolase Does Not Protect against Endotoxin-Mediated Hepatic Inflammation

Department of Biopharmaceutical Sciences, University of California, San Francisco, California, USA.
Journal of Pharmacology and Experimental Therapeutics (Impact Factor: 3.97). 10/2008; 327(3):707-15. DOI: 10.1124/jpet.108.142398
Source: PubMed


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.


Available from: Christophe Morisseau
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    • "Moreover, these effects correlated with decreased activation of the key transcription factor NF-κB [40]. By contrast, another study found that to sEH−/− null mice were not protected from LPS-induced inflammatory gene expression or neutrophil recruitment in the liver, and that treatment with the sEH inhibitor AUDA also had minimal effect liver inflammation, despite higher levels of endogenous EETs [46]. This suggests that either the effects of EETs are organ specific, or that liver is more susceptible to endotoxin shock. "
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    ABSTRACT: Epoxyeicosatrienoic acids (EETs) are generated by the activity of both selective and also more general cytochrome p450 (CYP) enzymes on arachidonic acid and inactivated largely by soluble epoxide hydrolase (sEH), which converts them to their corresponding dihydroxyeicosatrienoic acids (DHETs). EETs have been shown to have a diverse range of effects on the vasculature including relaxation of vascular tone, cellular proliferation, and angiogenesis as well as the migration of smooth muscle cells. This paper will highlight the growing evidence that EETs also mediate a number of anti-inflammatory effects in the cardiovascular system. In particular, numerous studies have demonstrated that potentiation of EET activity using different methods can inhibit inflammatory gene expression and signalling pathways in endothelial cells and monocytes and in models of cardiovascular diseases. The mechanisms by which EETs mediate their effects are largely unknown but may include direct binding to peroxisome proliferator-activated receptors (PPARs), G-protein coupled receptors (GPCRs), or transient receptor potential (TRP) channels, which initiate anti-inflammatory signalling cascades.
    International journal of vascular medicine 07/2012; 2012(1):605101. DOI:10.1155/2012/605101
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    • "NF-␬B activity was measured by using a Quantitation NF-␬B EIA kit (Oxford Biomedical Research, Oxford, MI) as described previously (Fife et al., 2008). This chemiluminescence assay uses an oligonucleotide containing the DNA binding NF-␬B consensus sequence bound to a 96-well EIA plate. "
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    ABSTRACT: Acute kidney injury is associated with a significant inflammatory response that has been the target of renoprotection strategies. Epoxyeicosatrienoic acids (EETs) are anti-inflammatory cytochrome P450-derived eicosanoids that are abundantly produced in the kidney and metabolized by soluble epoxide hydrolase (sEH; Ephx2) to less active dihydroxyeicosatrienoic acids. Genetic disruption of Ephx2 and chemical inhibition of sEH were used to test whether the anti-inflammatory effects of EETs, and other lipid epoxide substrates of sEH, afford protection against cisplatin-induced nephrotoxicity. EET hydrolysis was significantly reduced in Ephx2(-/-) mice and was associated with an attenuation of cisplatin-induced increases in serum urea nitrogen and creatinine levels. Histological evidence of renal tubular damage and neutrophil infiltration was also reduced in the Ephx2(-/-) mice. Likewise, cisplatin had no effect on renal function, neutrophil infiltration, or tubular structure and integrity in mice treated with the potent sEH inhibitor 1-adamantan-1-yl-3-(1-methylsulfonyl-piperidin-4-yl-urea) (AR9273). Consistent with the ability of EETs to interfere with nuclear factor-κB (NF-κB) signaling, the observed renoprotection was associated with attenuation of renal NF-κB activity and corresponding decreases in the expression of tumor necrosis factor (TNF) α, TNF receptor (TNFR) 1, TNFR2, and intercellular adhesive molecule-1 before the detection of tubular injury. These data suggest that EETs or other fatty acid epoxides can attenuate cisplatin-induced kidney injury and sEH inhibition is a novel renoprotective strategy.
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    • "Other lipogenesis-related genes with a similar temporal expression pattern include ELOVL family member 6, elongation of long chain fatty acids (Elovl6), transketolase (Tkt), butyryl Coenzyme A synthetase 1 (Bucs1), malic enzyme 1 (Me1), uncoupling protein 1 (Ucp1) and others (Table S2). Epoxide hydrolase 2 (EPHX2) is an important enzyme involved in the metabolic breakdown of arachidonic acid-derived eicosanoids [35]. The higher expression of Plaa noted previously, Figure 7F, makes the chronically lower expression of Ephx2 in the GK population (Figure 9C) quite relevant. "
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