title: Role of Toll-like receptors 2 and 4 in the induction of cyclooxygenase-2 in vascular smooth muscle.
abstract: Bacteria stimulate macrophages as part of normal host defense. However, when this response is not limited, vascular smooth muscle may also be activated to express "vasoactive" genes (e.g., cyclooxygenase), leading to vascular collapse and septic shock. In macrophages, Toll-like receptors (TLRs) 4 and 2 transduce responses to Gram-negative and Gram-positive bacteria, respectively. However, the role of these TLRs in sensing bacteria in vascular smooth muscle is unclear. To address this question, we have cultured vascular smooth muscle cells from mice deficient in TLR4 (TLR4(-/-) mice), mice deficient in TLR2 (TLR2(-/-) mice), or control mice. Cells cultured from control or TLR2(-/-) mice, but not from TLR4(-/-) mice, expressed cyclooxygenase-2 and released increasing levels of prostaglandin E(2) after stimulation with whole Escherichia coli bacteria; the combination of IL-1beta plus TNF-alpha induced cyclooxygenase-2 in cells cultured from all three groups of animals. By contrast, Staphylococcus aureus affected cyclooxygenase-2 expression in two distinct ways. First, S. aureus induced a transient inhibition of cyclooxygenase-2 expression, which was overcome with time, and increased protein expression was noted. The effects of S. aureus on cyclooxygenase-2 expression were TLR2- and not TLR4-dependent. Thus, we show that Gram-positive and Gram-negative bacteria induce cyclooxygenase-2 in vascular smooth muscle with differing temporal profiles but with appropriate TLR2-versus-TLR4 signaling. These data have important implications for our understanding of the innate immune response in vascular cells and how it may impact vascular disease.
authors.affiliation: Cardiothoracic Pharmacology, Unit of Critical Care Medicine, Royal Brompton Hospital, Faculty of Medicine, Imperial College, London SW3 6LY, UK.
authors.forename: Rosario
authors.initials: R
authors.lastname: Jimenez
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Belcher
authors.forename: Shiranee
authors.initials: S
authors.lastname: Sriskandan
authors.forename: Ruth
authors.initials: R
authors.lastname: Lucas
authors.forename: Shaun
authors.initials: S
authors.lastname: McMaster
authors.forename: Ivana
authors.initials: I
authors.lastname: Vojnovic
authors.forename: Timothy D
authors.initials: TD
authors.lastname: Warner
authors.forename: Jane A
authors.initials: JA
authors.lastname: Mitchell
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D051546:Cyclooxygenase 2; D015232:Dinoprostone / Q000096:biosynthesis; D004790:Enzyme Induction / Q000187:drug effects; D004926:Escherichia coli / Q000472:pathogenicity; D006801:Humans; D007375:Interleukin-1 / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000633:toxicity; D008565:Membrane Proteins; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism*; D011451:Prostaglandin-Endoperoxide Synthases / Q000096:biosynthesis*; D011956:Receptors, Cell Surface / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000494:pharmacology; D013211:Staphylococcus aureus / Q000472:pathogenicity; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
chemical_list: D007375:Interleukin-1; D008070:Lipopolysaccharides; D008565:Membrane Proteins; D011956:Receptors, Cell Surface; D011994:Recombinant Proteins; C493486:Tlr2 protein, mouse; C493487:Tlr4 protein, mouse; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; D014409:Tumor Necrosis Factor-alpha; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; D015232:Dinoprostone