Glycerylprostaglandin synthesis by resident peritoneal macrophages in response to a zymosan stimulus.
Cyclooxygenase (COX)-2 oxygenates arachidonic acid (AA) and 2-arachidonylglycerol (2-AG) to endoperoxides, which are subsequently transformed to prostaglandins (PGs) and glycerylprostaglandins (PG-Gs). PG-G formation has not been demonstrated in intact cells treated with a physiological agonist. Resident peritoneal macrophages, which express COX-1, were pretreated with lipopolysaccharide to induce COX-2. Addition of zymosan caused release of 2-AG and production of the glyceryl esters of PGE2 and PGI2 over 60 min. The total quantity of PG-Gs (16 +/- 6 pmol/10(7) cells) was much lower than that of the corresponding PGs produced from AA (21,000 +/- 7,000 pmol/10(7) cells). The differences in PG-G and PG production were partially explained by differences in the amounts of 2-AG and AA released in response to zymosan. The selective COX-2 inhibitor, SC236, reduced PG-G and PG production by 49 and 17%, respectively, indicating a significant role for COX-1 in PG-G and especially PG synthesis. Time course studies indicated that COX-2-dependent oxygenation rapidly declined 20 min after zymosan addition. When exogenous 2-AG was added to macrophages, a substantial portion was hydrolyzed to AA and converted to PGs; 1 microm 2-AG yielded 820 +/- 200 pmol of PGs/10(7) cells and 78 +/- 41 pmol of PG-Gs/10(7) cells. SC236 reduced PG-G and PG production from exogenous 2-AG by 88 and 76%, respectively, indicating a more significant role for COX-2 in the utilization of exogenous substrate. In conclusion, lipopolysaccharide-pretreated macrophages produce PG-Gs from endogenous 2-AG during zymosan phagocytosis, but PG-G formation is limited by substrate hydrolysis and inactivation of COX-2.
Rouzer
Carol A
CA
Department of Biochemistry, the Vanderbilt Institute of Chemical Biology, the Center in Molecular Toxicology, Nashville, TN 37232-0146, USA.
Marnett
Lawrence J
LJ
D000818:Animals; D001095:Arachidonic Acids / Q000378:metabolism; D002460:Cell Line; D051546:Cyclooxygenase 2; D015232:Dinoprostone / Q000096:biosynthesis; D063388:Endocannabinoids; D011464:Epoprostenol / Q000096:biosynthesis; D005989:Glycerides / Q000096:biosynthesis* / Q000378:metabolism; D006868:Hydrolysis; D008070:Lipopolysaccharides / Q000494:pharmacology; D017737:Macrophages, Peritoneal / Q000378:metabolism*; D051379:Mice; D008815:Mice, Inbred Strains; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism; D011453:Prostaglandins / Q000096:biosynthesis*; D015054:Zymosan / Q000502:physiology*
D001095:Arachidonic Acids; D063388:Endocannabinoids; D005989:Glycerides; D008070:Lipopolysaccharides; D011453:Prostaglandins; C094503:glyceryl 2-arachidonate; D015054:Zymosan; D011464:Epoprostenol; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases; D015232:Dinoprostone