Endothelin-1 accentuates the proatherosclerotic effects associated with C-reactive protein
Read at the Eighty-sixth Annual Meeting of The American Association for Thoracic Surgery, Philadelphia, Pa, April 29-May 3, 2006.
Received 28 April 2006; received in revised form 18 October 2006; accepted 1 November 2006. published online 29 March 2007.
Objectives
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 μg), 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 Cλ compared with control (P = .01). Furthermore, coincubation of C-reactive protein with endothelin-1 led to a synergistic inhibition of protein kinase Cλ 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 Cλ 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.
aHeart Transplant Program, Toronto General Hospital, University Health Network, University of Toronto, Toronto, Ontario, Canada
bDivision of Cardiac Surgery, University of Toronto, Toronto, Ontario, Canada
cDivision of Cardiology, University of Toronto, Toronto, Ontario, Canada.
Address for reprints: Vivek Rao, MD, PhD, FRCS, Alfredo and Teresa DeGasperis Chair in Heart Failure Surgery, 4N-464, Toronto General Hospital, 200 Elizabeth Street, Toronto, Ontario, M5G 2C4, Canada
Supported by the Heart and Stroke Foundation of Ontario (Grant # NA 5868), the Canadian Institutes for Health Research, the Thoracic Surgery Foundation for Research and Education, the Tailored Advanced Collaborative Training in Cardiovascular Science for Research Fellows, and the Physician Services Incorporated Foundation Grant for Research Fellows. D.R. is a Research Fellow of the TSFRE, PSI and TACTICS; V.R. is a CIHR New Investigator.
Manuscript accepted for the C. Walton Lillehei Resident Forum Session at the Annual Meeting of the American Association for Thoracic Surgery.
ABSTRACT