Incorporation of 15-hydroxyeicosatrienoic acid in specific phospholipids of cultured human keratinocytes and psoriatic plaques.
15-hydroxyeicosatrienoic acid, 15-HETrE, the 15-lipoxygenase product of dihomogammalinolenic acid (DGLA), can inhibit the biosynthesis of the proinflammatory eicosanoids leukotriene B4 (LTB4) and 12-hydroxyeicosatetraenoic acid (12-HETE). The purpose of the present study was to investigate the incorporation of [14C]15-HETrE in specific membrane phospholipids of cultured human keratinocytes in vitro. [14C]15-HETrE was rapidly incorporated into keratinocytes. When a plateau was reached after 3 hours, 15% of the added radioactivity was incorporated into lipids; 96.5% into phospholipids (PL) and 3.5% into neutral lipids (NL). Within the phospholipid classes, [14C]15-HETrE showed selectivity for incorporation into phosphatidylinositol (PI). The mean proportion of [14C]15-HETrE in the PI, phosphatidylcholine (PC) and phosphatidylethanolamine (PE) was 83.2%, 8.5% and 8.3%, respectively. We then investigated the incorporation of 15-HETrE in epidermal phospholipids of psoriatic skin intralesionally injected with 15-HETrE. Four patients took part in the study. In each patient four identical plaques were injected with 0.65 ml of 2.0 microM, 6.2 microM, 18.6 microM of 15-HETrE (0.4 micrograms, 1, 2 micrograms and 3.6 micrograms respectively) or 0.65 ml of 0.88% NaCl twice a week. After 3 wk keratome biopsies were obtained from the treated plaques. Phospholipids extracted from the skin biopsies were separated into major classes by two-dimensional thin layer chromatography. 15-HETrE was then released from specific phospholipids after treatment with phospholipase A2 and identified by reverse phase and straight phase high performance liquid chromatography. There was a dose-dependent incorporation of 15-HETrE into the specific phospholipids PI and PC. When expressed as ng 15-HETrE/micrograms phospholipid phosphate, 15-HETrE accumulated preferentially in PI.(ABSTRACT TRUNCATED AT 250 WORDS)
Heitmann
J
J
Department of Dermatology, Marselisborg Hospital, University of Aarhus, Denmark.
Iversen
L
L
Kragballe
K
K
Ziboh
V A
VA
D015126:8,11,14-Eicosatrienoic Acid / Q000378:metabolism; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000008:administration & dosage / Q000627:therapeutic use; D002478:Cells, Cultured; D002851:Chromatography, High Pressure Liquid; D002855:Chromatography, Thin Layer; D006801:Humans; D006893:Hydroxyeicosatetraenoic Acids / Q000008:administration & dosage / Q000378:metabolism* / Q000493:pharmacokinetics / Q000627:therapeutic use; D015552:Injections, Intralesional; D015603:Keratinocytes / Q000378:metabolism* / Q000473:pathology; D010713:Phosphatidylcholines / Q000378:metabolism; D010716:Phosphatidylinositols / Q000378:metabolism; D010741:Phospholipases A / Q000378:metabolism; D054467:Phospholipases A2; D010743:Phospholipids / Q000378:metabolism*; D011565:Psoriasis / Q000188:drug therapy / Q000473:pathology*
D000894:Anti-Inflammatory Agents, Non-Steroidal; D006893:Hydroxyeicosatetraenoic Acids; D010713:Phosphatidylcholines; D010716:Phosphatidylinositols; D010743:Phospholipids; C095123:15-hydroxyeicosatrienoic acid; D010741:Phospholipases A; D054467:Phospholipases A2; D015126:8,11,14-Eicosatrienoic Acid