CYP450-derived oxylipins mediate inflammatory resolution

Abstract

Resolution of inflammation has emerged as an active process in immunobiology, with cells of the mononuclear phagocyte system being critical in mediating efferocytosis and wound debridement and bridging the gap between innate and adaptive immunity. Here we investigated the roles of cytochrome P450 (CYP)-derived epoxy-oxylipins in a well-characterized model of sterile resolving peritonitis in the mouse. Epoxy-oxylipins were produced in a biphasic manner during the peaks of acute (4 h) and resolution phases (24-48 h) of the response. The epoxygenase inhibitor SKF525A (epoxI) given at 24 h selectively inhibited arachidonic acid-and linoleic acid-derived CYP450-epoxy-oxlipins and resulted in a dramatic influx in monocytes. The epoxI-recruited monocytes were strongly GR1 hi and Ly6c lo monocytes, resident macrophages, and recruited dendritic cells all showed a dramatic change in their resolution signature following in vivo epoxI treatment. Markers of macrophage differentiation CD11b, MerTK, and CD103 were reduced, and monocyte-derived macrophages and resident macrophages ex vivo showed greatly impaired phagocytosis of zymosan and efferocytosis of apoptotic thymocytes following epoxI treatment. These findings demonstrate that epoxy-oxylipins have a critical role in monocyte lineage recruitment and activity to promote inflammatory resolution and represent a previously unidentified internal regulatory system governing the establishment of adaptive immunity.oxylipins | resolution | monocyte | phagocytosis | epoxygenase M onocytes and monocyte-derived macrophages play a critical role in chronic inflammation, in part via the production and release of lipid mediators (1). One such lipid precursor, arachidonic acid, is metabolized into families of biologically active mediators by the cyclooxygenase, lipoxygenase, and cytochrome P450 (CYP) pathways (2, 3). CYPs metabolize arachidonic acid by: (i) an epoxygenase activity that catalyzes the conversion of arachidonic acid to epoxyeicosatrienoic acids (EETs); (ii) a lipoxygenase-like activity that metabolizes arachidonic acid to midchain hydroxyeicosatetraenoic acids (HETEs); and (iii) ω-and ω-1-hydroxylase activity, which produces ω-terminal HETEs (3). In addition to arachidonic acid, CYPs with epoxygenase activity can also metabolize alternative polyunsaturated fatty acids such as linoleic acid and docosahexaenoic acid into a series of products including epoxyoctadacamonoenoic acids (EpOMEs) and 19,20-epoxydocosapentaenoic acid (EpDPE), respectively, whose functions remain poorly understood (3-5).The main polyunsaturated fatty acid-metabolizing CYPs belong to the CYP2 family, in particular the CYP2J and CYP2C subfamilies (3, 4, 6, 7). Moreover, these CYP-lipid-metabolizing enzymes are the primary sources of eicosanoids in small blood vessels, the kidney, liver, lung, intestines, heart, and pancreas (3, 7). In most organs, EETs and related epoxygenase products are metabolically unstable and are rapidly metabolized. The major pathway that regulates EET metabolism is that catalyzed...

Epoxygenated Fatty Acids Inhibit Retinal Vascular Inflammation

“…Our in vitro experiments focused on the effects of EET and EDP on the retinal endothelial cells alone. Indeed, evidence from other studies suggests that these epoxides may also exert their effects on macrophages and monocytes425070717273. Hence, EET- and EDP-dependent effects on circulating cells may represent an important component of the in vivo pathogenesis that is absent in our in vitro studies.…”

Modulation of mitochondrial dysfunction and endoplasmic reticulum stress are key mechanisms for the wide-ranging actions of epoxy fatty acids and soluble epoxide hydrolase inhibitors

“…However, the rate of EpFAs synthesis is not constant and seems to be acutely responsive to multiple stimuli, particularly under pathological conditions. A recent report demonstrated a biphasic change in EpFA levels over the course of 0–24h of inflammation [6]. Clearly, there are pools of quantifiable intra- and extra-cellular, free acid EpFAs both of which are stabilized and augmented by sEH inhibitors.…”

“…Progress attained within the last decade strongly suggests that EETs and other EpFA are opposing counterparts to the largely pro-inflammatory prostanoids, leukotrienes and HETEs [5, 6]. This P450 branch of the ARA cascade is attracting increasing attention both in fundamental regulatory biology and as a clinical target to treat a variety of diseases [7–9].…”

MFSD2A Promotes Endothelial Generation of Inflammation-Resolving Lipid Mediators and Reduces Colitis in Mice

“…The main PUFA-metabolizing CYPs belong to the CYP2 family, in particular the CYP2J and CYP2C subfamilies, all localized in the endoplasmic reticulum (ER) 24 . The CYP2C subfamily represents one of the two major pieces of the intestinal P450 pie 25 .…”

“…The two proteins were indeed found in close proximity ( Figure 4H), but did not physically interact, as shown by co-immunoprecipitation studies (Supplementary Figure 3J). We next inhibited CYP2C enzymes in MFSD2A-OE healthy HIMECs using Proadifen hydrochloride, a chemical agent known to be highly selective for the CYP-epoxygenase pathway 24 . Proadifen was able to abate the resolving effects exerted by MFSD2A overexpression in TNFα-treated HIMECs, in terms of increased TEER ( Figure 4I), and higher production of inflammatory cytokines and markers of endothelium activation ( Figure 4J).…”