title: Lipopolysaccharide induces interleukin-6 release from rat peritoneal macrophages in vitro: evidence for a novel mechanism.
abstract: Interleukin-6 (IL-6) is a cytokine involved in the terminal differentiation of B-cells, T-cell activation, and secretion of hepatic acute phase proteins. The production of IL-6 is regulated by many factors, including IL-1 and lipopolysaccharide (LPS). Because IL-6 may be an important contributor to the effects of LPS in inflammation and septic shock, we investigated the ability of LPS to induce IL-6 release from peritoneal macrophages (m phi) in vitro. M phi were isolated from male Long-Evans rats, and cultured in 96-well tissue culture plates at 1 x 10(5) cells/well in serum-free RPMI-1640 medium. Following a 2-hr attachment period, the cells were rinsed twice to remove the nonadherent cells. LPS (0.006-100 ng/ml) stimulated IL-6 release by six- to 12-fold during a 4 hr incubation. In contrast, IL-1 beta (0.006-100 ng/ml) had no effect. Because cyclooxygenase metabolites of arachidonic acid are increased by LPS, we determined the effects of indomethacin (a cyclooxygenase inhibitor) and CGS8515 (a 5-lipoxygenase inhibitor) on LPS-induced IL-6 release. Neither indomethacin (10 microM) nor CGS8515 (2.5 microM) had any effect on basal or LPS-induced IL-6 release. Very low concentrations of LPS (0.01-1,000 pg/ml) stimulated IL-6 by two- to threefold. Pertussis toxin (10 ng/ml), which inactivates Gi protein, had no effect on LPS-induced IL-6 release from mø. Thromboxane B2 (TXB2) concentrations were also elevated with as little as 0.1 pg/ml LPS; however, pertussis toxin inhibited LPS-stimulated TXB2 release.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Physiology, Medical University of South Carolina, Charleston 29425-2258.
authors.forename: R M
authors.initials: RM
authors.lastname: Wright
authors.forename: C S
authors.initials: CS
authors.lastname: Holladay
authors.forename: B L
authors.initials: BL
authors.lastname: Spangelo
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000502:physiology; D015214:Antigens, Differentiation, Myelomonocytic / Q000502:physiology; D066298:In Vitro Techniques; D007213:Indomethacin / Q000494:pharmacology; D007375:Interleukin-1 / Q000494:pharmacology; D015850:Interleukin-6 / Q000378:metabolism*; D018950:Lipopolysaccharide Receptors; D008070:Lipopolysaccharides / Q000494:pharmacology*; D017737:Macrophages, Peritoneal / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D009285:Naphthoquinones / Q000494:pharmacology; D037342:Pertussis Toxin; D051381:Rats; D015398:Signal Transduction / Q000187:drug effects; D013929:Thromboxane B2 / Q000096:biosynthesis; D010566:Virulence Factors, Bordetella / Q000494:pharmacology; D062367:ortho-Aminobenzoates / Q000494:pharmacology
chemical_list: D015703:Antigens, CD; D015214:Antigens, Differentiation, Myelomonocytic; D007375:Interleukin-1; D015850:Interleukin-6; D018950:Lipopolysaccharide Receptors; D008070:Lipopolysaccharides; D009285:Naphthoquinones; D010566:Virulence Factors, Bordetella; D062367:ortho-Aminobenzoates; C055523:methyl 2-((3,4-dihydro-3,4-dioxo-1-naphthalenyl)amino)benzoate; D013929:Thromboxane B2; D037342:Pertussis Toxin; D007213:Indomethacin