title: Endothelin-1 accentuates the proatherosclerotic effects associated with C-reactive protein.
abstract: OBJECTIVE
  The proinflammatory marker C-reactive protein has been demonstrated to play a role in the development of atherosclerosis. Endothelin-1 and nitric oxide homeostasis is crucial for normal vasomotor function, limiting inflammatory activation and maintaining a nonthrombogenic endothelial surface. In addition to its vasoactive properties, endothelin-1 is also an inflammatory cytokine. We have previously demonstrated that C-reactive protein impairs endothelial cell nitric oxide production. Protein kinase C, an important signal transducer within the cell, is involved in several cellular responses to external stimuli. We therefore sought to determine whether endothelin-1 exposure modulates C-reactive protein's effects on nitric oxide production via protein kinase C.
  
  
  METHODS
  Endothelial cells were incubated with C-reactive protein (200 microg), endothelin-1 (100 nM), C-reactive protein + endothelin-1, or phosphate-buffered saline solution (control) for 24 hours. After exposure, endothelial nitric oxide synthase expression was determined in addition to total nitric oxide production and protein kinase C translocation and activity.
  
  
  RESULTS
  Endothelial nitric oxide synthase protein expression was reduced following incubation with C-reactive protein and endothelin-1 treatment compared with baseline by 40% and 45%, respectively (P = .04); however, no additive effects were seen with coincubation. C-reactive protein produced a 47% decrease in nitric oxide production compared with control. Coincubation with endothelin-1 resulted in a synergistic 70% reduction in nitric oxide production (P = .001). C-reactive protein exposure inhibited translocation of protein kinase C lambda compared with control (P = .01). Furthermore, coincubation of C-reactive protein with endothelin-1 led to a synergistic inhibition of protein kinase C lambda translocation (P = .01). C-reactive protein exposure reduced protein kinase C activity by 40% compared with control (P = .02), although coincubation with endothelin-1 had a synergistic reduction in activity (P = .02).
  
  
  CONCLUSIONS
  Our results indicate that endothelin-1 exposure accentuated C-reactive protein's impairment of endothelial nitric oxide production via synergistic inhibition of protein kinase C lambda translocation and activity. Our investigations suggest that endothelin-1 inhibition and protein kinase C stimulation may provide a novel therapeutic strategy to improve vascular nitric oxide homeostasis and mitigate the proatherosclerotic effects of C-reactive protein.
authors.affiliation: Division of Cardiac Surgery, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Danny
authors.initials: D
authors.lastname: Ramzy
authors.forename: Vivek
authors.initials: V
authors.lastname: Rao
authors.forename: Laura C
authors.initials: LC
authors.lastname: Tumiati
authors.forename: Ning
authors.initials: N
authors.lastname: Xu
authors.forename: Rohit
authors.initials: R
authors.lastname: Sheshgiri
authors.forename: Jessica
authors.initials: J
authors.lastname: Jackman
authors.forename: Diego H
authors.initials: DH
authors.lastname: Delgado
authors.forename: Heather J
authors.initials: HJ
authors.lastname: Ross
mesh_terms: D000470:Alkaloids / Q000494:pharmacology; D050197:Atherosclerosis / Q000378:metabolism*; D053119:Benzophenanthridines / Q000494:pharmacology; D000077300:Bosentan; D002097:C-Reactive Protein / Q000494:pharmacology*; D002478:Cells, Cultured; D016207:Cytokines / Q000494:pharmacology; D019332:Endothelin-1 / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D004730:Endothelium, Vascular / Q000378:metabolism* / Q000503:physiopathology; D006706:Homeostasis; D006801:Humans; D009281:Naphthalenes / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D011493:Protein Kinase C / Q000378:metabolism; D012501:Saphenous Vein; D013449:Sulfonamides / Q000494:pharmacology
chemical_list: D000470:Alkaloids; D053119:Benzophenanthridines; D016207:Cytokines; D019332:Endothelin-1; D009281:Naphthalenes; D013449:Sulfonamides; D009569:Nitric Oxide; D002097:C-Reactive Protein; C016299:chelerythrine; D052250:Nitric Oxide Synthase Type III; D011493:Protein Kinase C; C058819:calphostin C; D000077300:Bosentan