Fig. 2.

The 5 lipoxygenase enzymatic pathway. Following cellular activation, 5-LO migrates from the cytosol to the nuclear membrane where it is able to interact with the 5LO activating protein (FLAP) and by oxidizing arachidonic acid on carbon 5 generates first 5hydroperoxyeicosatetraenoic acid (5-HPETE), which can then be converted to 5-hydroxyeicosatetraenoic acid (5-HETE), or leukotriene A4 (LTA4). LTA4 can be metabolized in leukotriene B4 (LTB4) by the action of a hydrolase, or into leukotriene C4 (LTC4) by the action of a synthase. LTC4 in turn can be transformed into leukotriene D4 (LTD4) by the 𝛾-glutamyl transferase-1 and then into leukotriene E4 (LTE4) by the LTD4 dipeptidase enzyme.LTB4 action is mediated by bonding to the leukotriene B receptors(BLT1,and LTB2),where as the LTC4, LTD4 and LTE4 action is mediated by their binding to the cysteinyl leukotriene receptors (CysLT). In both cases, the binding will elicit a GPCR-dependent intracellular signaling biological event resulting in immune activation and inflammatory responses.