Cytochrome P450 Derived Eicosanoids and Inflammation

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ABSTRACT: Inflammation is a fundamental process which plays an integral role in the pathogenesis of numerous disease states in humans. Nuclear factor kappa B (NF-¿B) is a central mediator of the inflammatory response via transcriptional activation of cytokine, chemokine and cellular adhesion molecule expression. Consequently, identification of novel strategies aimed at inhibition of this pathological process offers substantial therapeutic potential. Arachidonic acid is oxidatively metabolized by cytochrome P450 (CYP) epoxygenases from the CYP2J and CYP2C subfamilies to epoxyeicosatrienoic acids (EETs) in hepatic and extra-hepatic tissue. The EETs are rapidly hydrolyzed by soluble epoxide hydrolase (sEH) to less active dihydroxyeicosatrienoic acids (DHETs). Arachidonic acid is also metabolized to 20-hydroxyeicosatetraenoic acid (20-HETE) by CYP ¿- hydroxylases from the CYP4A and CYP4F subfamilies. Recent evidence has demonstrated that CYP-derived EETs and 20-HETE possess anti- and pro-inflammatory effects, respectively. However, the contribution of CYP-mediated eicosanoid metabolism to the regulation of inflammation in vivo has not been rigorously characterized. We hypothesize that the functional balance between CYP epoxygenase- and CYP ¿- hydroxylase-mediated arachidonic acid metabolism is integral to the regulation of NF-¿B-mediated inflammatory responses in vivo, and modulation of this balance in favor of the CYP epoxygenase pathway offers substantial therapeutic potential. The primary objectives of this proposal are to: (1) define the impact of the inflammatory response on hepatic and extra-hepatic CYP-mediated eicosanoid metabolism, (2) define the functional role of CYP epoxygenase-mediated EET biosynthesis and sEH-mediated EET hydrolysis in the regulation of inflammation, and (3) characterize the relative impact of CYP epoxygenase and CYP ¿- hydroxylase pathway modulation on inflammatory responses in vivo. This project will utilize novel transgenic and knock-out mice and pharmacological tools to manipulate CYP-mediated eicosanoid metabolism in vivo, while characterizing NF-¿B-mediated inflammatory responses using established molecular biology and analytical techniques. Collectively, this series of novel experiments will define the mechanistic contribution of CYP epoxygenase-derived EETs and CYP ¿-hydroxylase-derived 20-HETE to the regulation of hepatic and extra-hepatic inflammatory responses in vivo, and facilitate the development of new anti-inflammatory strategies with potential therapeutic application to numerous disease states in humans.