Abstract
Human neutrophils, enriched by dietary supplementation with eicosapentaenoic acid, form leukotriene (LT)B5 in addition to LTB4 upon stimulation. LTB5 is one order of magnitude less biologically active than the potent chemokinetic and chemoattractant LTB4. Catabolites of LTB5 have not yet been characterized in vitro and ex vivo. It is unknown whether catabolism of LTB5 interferes with catabolism of LTB4. This report describes catabolism of LTB5 to 20-OH-LTB5, which in turn is catabolized to 20-COOH-LTB5. The structures of the two catabolites were established by UV-absorbance, behavior on reverse-phase high-performance liquid chromatography, enzymatic analysis of human neutrophils, and gas chromatography-mass spectrometry. In vitro, formation of LTB4 was delayed and formation of its catabolites was depressed by exogenous eicosapentaenoic acid. By supplementing the diet of six volunteers with 5 g eicosapentaenoic acid/day for 7 days, eicosapentaenoic acid quadrupled in neutrophil phospholipid fatty acids. Consequently, LTB5, 20-OH-LTB5, and 20-COOH-LTB5 were detected ex vivo. In contrast to the findings in vitro, however, levels of LTB4, 20-OH-LTB4, and 20-COOH-LTB4 were unaltered by the dietary intervention. Thus, in vitro, but not ex vivo, addition of eicosapentaenoic acid, and subsequent formation of LTB5, impeded catabolism of proinflammatory LTB4.
Highlights
Human neutrophils, enriched by dietary supplementation with eicosapentaenoic acid, form leukotriene (LT)BS in addition to LTB4upon stimulation
A new peak was observed on feverse-phase HPLC (HPLC), eluting prior to 20-OH-LTB4, representing a compound more polar than LTBS.An even more polar peak was noted prior to 20-COOH-LTB4
We studied human catabolism of LTB, a compound that is formed by stimulated neutrophils after enrichment of the diet with eicosapentaenoic acid (EPA) [1,2,3]
Summary
Human neutrophils, enriched by dietary supplementation with eicosapentaenoic acid, form leukotriene (LT)BS in addition to LTB4upon stimulation. Catabolites of LTB5 have not yet been characterized in vitro and ex vivo. It is unknown whether catabolism of LTB5 interferes with catabolism of LTB4.This report describes catabolism of LTB5 to 20-OH-LTB5,which in turn is catabolized to 20-COOH-LTB5. Formation of LTB4 was delayed and formation of its catabolites was depressed by exogenous eicosapentaenoic acid. LTB5, 20-OH-LTB5, and 20-COOH-LTB5 were detected ex vivo. In contrast to the findings in vitro, levels of LTB4, 20-OH-LTB4, and 20-COOH-LTB4 were unaltered by the e dietary intervention. In vitro, but not ex vivo, addition of eicosapentaenoic acid, and subsequent formation of
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