title: Staphylococcal exoproducts down-regulate cyclooxygenase 1 and 2 in peritoneal macrophages.
abstract: Peritoneal macrophages (PMOs) are important components of the host defense against microbial infection in patients undergoing continuous ambulatory peritoneal dialysis (CAPD). Incubation of human PMOs with cell-free supernatant (BFS), prepared from Staphylococcus aureus, inhibited prostaglandin E2 (PGE2) and thromboxane B2 (TXB2) production. Slot-blot analysis of cyclooxygenase-1 (Cox-1) and Cox-2 demonstrated a decrease in both Cox-1 (29%) and, to a greater extent, Cox-2 (65%) protein expression after BFS stimulation. When competitive polymerase chain reaction (PCR) was used, the peak levels of Cox-1 and Cox-2 messenger ribonucleic acid (mRNA) in unstimulated PMOs were 0.304+/-0.13 pmol/L and 9.61+/-2.84 pmol/L (mean+/-SEM, n = 3), respectively. After exposure of samples to BFS for 30 minutes, the level of Cox-2 mRNA was reduced to 0.59+/-0.449 pmol/L (16-fold reduction, p < 0.05), and the level of Cox-1 mRNA was reduced to 0.02+/-0.002 pmol/L (15-fold reduction, p < 0.05). In contrast, these same PMOs showed an increased expression of IL-6 mRNA and increased secretion of IL-6 protein. These results indicate that prostaglandin production in PMOs is regulated by alterations in both immunoreactive Cox-1 and Cox-2. The down-regulation of Cox metabolism in these cells is primarily related to the delayed and depressed increase in the Cox-2 gene product.
authors.affiliation: Institute of Nephrology, University of Wales College of Medicine, Cardiff Royal Infirmary, United Kingdom.
authors.forename: R K
authors.initials: RK
authors.lastname: Mackenzie
authors.forename: N
authors.initials: N
authors.lastname: Topley
authors.forename: A
authors.initials: A
authors.lastname: Neubauer
authors.forename: G A
authors.initials: GA
authors.lastname: Coles
authors.forename: J D
authors.initials: JD
authors.lastname: Williams
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000906:Antibodies / Q000032:analysis; D018929:Cell Culture Techniques; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D015536:Down-Regulation / Q000502:physiology; D015777:Eicosanoids / Q000096:biosynthesis; D005098:Exotoxins / Q000494:pharmacology*; D005260:Female; D006801:Humans; D007527:Isoenzymes / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism; D017737:Macrophages, Peritoneal / Q000201:enzymology*; D008297:Male; D008565:Membrane Proteins; D008875:Middle Aged; D010531:Peritoneal Dialysis, Continuous Ambulatory; D016133:Polymerase Chain Reaction / Q000379:methods; D011451:Prostaglandin-Endoperoxide Synthases / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis / Q000187:drug effects; D013211:Staphylococcus aureus / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D000906:Antibodies; D015777:Eicosanoids; D005098:Exotoxins; D007527:Isoenzymes; D008565:Membrane Proteins; D012333:RNA, Messenger; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; C496511:PTGS1 protein, human; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases