%0 Generic %A Gimenez-Bastida, Juan Antonio %A Schneider, Claus %A Shibata, Takahiro %A Uchida, Koji %D 2019 %T Articulo 017 FASEB Journal.pdf %U https://hra.figshare.com/articles/dataset/Articulo_017_FASEB_Journal_pdf/7824140 %R 10.25376/hra.7824140.v1 %2 https://hra.figshare.com/ndownloader/files/14556620 %K arachidonic acid %K Hemiketals %K Arachidonic acid %K leukotriene %K Pharmacology %X The 2 hemiketal (HK) eicosanoids HKD2 and HKE2 are the major products of the biosynthetic crossover of the 5-lipoxygenase (5-LOX) and cyclooxygenase-2 (COX-2) pathways. HKs result from the rearrangement of a di-endoperoxide intermediate formed in the COX-2-dependent oxygenation of 5S-hydroxyeicosatetraenoic acid (5S-HETE). We analyzed HK biosynthesis in human leukocytes stimulated ex vivo and defined the biosynthetic roles of 5-LOX and COX-2, using inhibitors and incubations with exogenous substrates. Activation of leukocytes with LPS followed by treatment with the calcium ionophore A23187 resulted in the formation of PGE2, 5-HETE, and LTB4 as the principal metabolites of COX-2 and 5-LOX, respectively. The formation of HKD2 and HKE2 was highest after 15 min LPS treatment, and at that time, levels were similar to PGE2, but less than 5-HETE and LTB4 The time course of HK formation paralleled that of 5-HETE and LTB4, implying the availability of the 5S-HETE substrate as a limiting factor in biosynthesis rather than expression levels of COX-2. Specific inhibitors of COX-2 and 5-LOX decreased formation of HKD2 and HKE2 Platelets did not form HKs from exogenous 5S-HETE, implying that COX-1 is not involved. HKs are early products during an inflammatory event and require cells that express 5-LOX and COX-2 for their biosynthesis.-Giménez-Bastida, J. A., Shibata, T., Uchida, K., Schneider, C. Roles of 5-lipoxygenase and cyclooxygenase-2 in the biosynthesis of hemiketals E2 and D2 by activated human leukocytes. %I Health Research Alliance