Linoleic acid and dihomogammalinolenic acid inhibit leukotriene B4 formation and stimulate the formation of their 15-lipoxygenase products by human neutrophils in vitro. Evidence of formation of antiinflammatory compounds.
Enzymatic transformation of the n-6 polyunsaturated fatty acid (PUFA) arachidonic acid (AA) by the 5-lipoxygenase (LO) enzyme results in the formation of leukotrienes (LTs) including leukotriene B4 (LTB4), which is a potent mediator of inflammation. The purpose of the present study was to determine the effect of other n-6 fatty acids on the formation of LTB4 by human neutrophils and to determine if these n-6 fatty acids themselves may be transformed into products with antiinflammatory capacity. Purified neutrophils isolated from heparinized human venous blood were incubated with A23187 (5 microM) and different concentrations (0-100 microM) of the n-6 fatty acids linoleic acid (LA) and dihomo-gamma-linolenic acid (DGLA). LO products were determined by use of quantitative reversed-phase high performance liquid chromatography (RP-HPLC) and mass spectrometry. The formation of LTB4 was dose dependently inhibited by both LA (IC50 = 45 microM) and DGLA (IC50 = 40 microM). This inhibition of LTB4 formation was associated with a dose dependent increase in the formation of the respective 15-LO products of LA (13-hydroxy-octadecadienoic acid; 13-HODE) and DGLA (15-hydroxy-eicosatrienoic acid; 15-HETrE). To determine whether these 15-LO products themselves might inhibit LTB4 formation, neutrophils were incubated with 13-HODE and 15-HETrE. Both 15-LO products lead to a dose-dependent inhibition of LTB4 formation (IC50 = 7.5 microM and IC50 = 0.2 microM). For comparison the 15-LO product of AA, 15-hydroxy-eicosatetraenoic acid (15-HETE), also inhibited LTB4 formation (IC50 = 0.75 microM).(ABSTRACT TRUNCATED AT 250 WORDS)
Iversen
L
L
Department of Dermatology, Marselisborg Hospital, University of Aarhus, Denmark.
Fogh
K
K
Bojesen
G
G
Kragballe
K
K
D015126:8,11,14-Eicosatrienoic Acid / Q000494:pharmacology*; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000378:metabolism*; D001093:Arachidonate 15-Lipoxygenase / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D006801:Humans; D006893:Hydroxyeicosatetraenoic Acids / Q000096:biosynthesis; D066298:In Vitro Techniques; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D007975:Leukotriene B4 / Q000096:biosynthesis*; D019787:Linoleic Acid; D008041:Linoleic Acids / Q000096:biosynthesis / Q000494:pharmacology*; D013058:Mass Spectrometry; D009504:Neutrophils / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*
D000894:Anti-Inflammatory Agents, Non-Steroidal; D006893:Hydroxyeicosatetraenoic Acids; D008041:Linoleic Acids; D007975:Leukotriene B4; C024348:13-hydroxy-9,11-octadecadienoic acid; C025984:15-hydroxy-5,8,11,13-eicosatetraenoic acid; D019787:Linoleic Acid; D007770:L-Lactate Dehydrogenase; D001093:Arachidonate 15-Lipoxygenase; D015126:8,11,14-Eicosatrienoic Acid