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Cytochrome P450 epoxygenase gene function in hypoxic pulmonary vasoconstriction and pulmonary vascular remodeling.

ABSTRACT: We assessed pulmonary cytochrome P450 (CYP) epoxygenase expression and activity during hypoxia and explored the effects of modulating epoxygenase activity on pulmonary hypertension. The acute hypoxic vasoconstrictor response was studied in Swiss Webster mice, who express CYP2C29 in their lungs. Animals were pretreated with vehicle, the epoxygenase inhibitor (N-methylsulfonyl-6-[2-propargyloxyphenyl] hexanamide) or an inhibitor of the soluble epoxide hydrolase. Whereas the epoxygenase inhibitor attenuated hypoxic pulmonary constriction (by 52%), the soluble epoxide hydrolase inhibitor enhanced the response (by 39%), indicating that CYP epoxygenase-derived epoxyeicosatrienoic acids elicit pulmonary vasoconstriction. Aerosol gene transfer of recombinant adenovirus containing the human CYP2C9 significantly elevated mean pulmonary artery pressure and total pulmonary resistance indices, both of which were sensitive to the inhibitor sulfaphenazole. The prolonged exposure of mice to hypoxia increased CYP2C29 expression, and transcript levels increased 5-fold after exposure to normobaric hypoxia (FIO2 0.07) for 2 hours. This was followed by a 2-fold increase in protein expression and by a significant increase in epoxyeicosatrienoic acid production after 24 hours. Chronic hypoxia (7 days) elicited pulmonary hypertension and pulmonary vascular remodeling, effects that were significantly attenuated in animals continually treated with N-methylsulfonyl-6-[2-propargyloxyphenyl] hexanamide (-46% and -55%, respectively). Our results indicate that endogenously generated epoxygenase products are associated with hypoxic pulmonary hypertension in mice and that selective epoxygenase inhibition significantly reduces acute hypoxic pulmonary vasoconstriction and chronic hypoxia-induced pulmonary vascular remodeling. These observations indicate potential novel targets for the treatment of pulmonary hypertension and highlight a pivotal role for CYP epoxygenases in pulmonary responses to hypoxia.

SUBMITTER: Pokreisz P

PROVIDER: S-EPMC1993904 | biostudies-literature | 2006 Apr

REPOSITORIES: biostudies-literature

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Cytochrome P450 epoxygenase gene function in hypoxic pulmonary vasoconstriction and pulmonary vascular remodeling.

Pokreisz Peter P Fleming Ingrid I Kiss Ladislau L Barbosa-Sicard Eduardo E Fisslthaler Beate B Falck John R JR Hammock Bruce D BD Kim In-Hae IH Szelid Zsolt Z Vermeersch Pieter P Gillijns Hilde H Pellens Marijke M Grimminger Friedrich F van Zonneveld Anton-Jan AJ Collen Desire D Busse Rudi R Janssens Stefan S

Hypertension (Dallas, Tex. : 1979) 20060227 4

We assessed pulmonary cytochrome P450 (CYP) epoxygenase expression and activity during hypoxia and explored the effects of modulating epoxygenase activity on pulmonary hypertension. The acute hypoxic vasoconstrictor response was studied in Swiss Webster mice, who express CYP2C29 in their lungs. Animals were pretreated with vehicle, the epoxygenase inhibitor (N-methylsulfonyl-6-[2-propargyloxyphenyl] hexanamide) or an inhibitor of the soluble epoxide hydrolase. Whereas the epoxygenase inhibitor a ...[more]

PMID: 16505204

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Project description:This is the largest study describing the role of P450 epoxygenase metabolites in septic shock in humans and suggests a novel therapeutic target.ObjectivesOxylipins are oxidative breakdown products of cell membrane fatty acids. Animal models have demonstrated that oxylipins generated by the P450 epoxygenase pathway may be implicated in septic shock pathology. However, these mediators are relatively unexplored in humans with septic shock. We aimed to determine if there were patterns of oxylipins that were associated with 28-day septic shock mortality and organ dysfunction.DesignRetrospective analysis of samples collected during the Vasopressin versus Norepinephrine as Initial Therapy in Septic Shock trial.SettingICUs in the United Kingdom.ParticipantsAdults recruited within 6 hours of onset of septic shock.Main outcomes and measuresOxylipin profiling was performed on 404 serum samples from 152 patients using liquid chromatography-mass spectrometry.ResultsNonsurvivors were found to have higher levels of 14,15-dihydroxyeicosatrienoic acid (DHET) at baseline than survivors (p = 0.02). Patients with 14,15-DHET levels above the lower limit of quantification of the assay were more likely to die than patients with levels below this limit (hazard ratio, 2.3; 95% CI, 1.2-4.5). Patients with measurable 14,15-DHET had higher levels of organ dysfunction and fewer renal failure-free days than those in whom it was unmeasurable. Considering samples collected over the first week of intensive care stay, measurable levels of DHET species were associated with higher daily Sequential Organ Failure Assessment scores that appeared to be accounted for predominantly by the liver component. Measurable 14,15-DHET showed positive correlation with bilirubin (r s = 0.38; p < 0.001) and lactate (r s = 0.27; p = 0.001).Conclusions and relevanceThe P450 epoxygenase-derived DHET species of oxylipins were associated with organ, particularly liver, dysfunction in septic shock and 14,15-DHET was associated with septic shock mortality. These results support further investigation into the role of the P450 epoxygenase-derived oxylipins in sepsis and suggest that this pathway may offer a novel therapeutic strategy in septic shock.

Dataset Information

Cytochrome P450 epoxygenase gene function in hypoxic pulmonary vasoconstriction and pulmonary vascular remodeling.

Publications

Cytochrome P450 epoxygenase gene function in hypoxic pulmonary vasoconstriction and pulmonary vascular remodeling.

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