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Activated nuclear factor-kappaB is present in the coronary vasculature in experimental hypercholesterolemia
S H Wilson1, N M Caplice, R D Simari
1Division of Cardiovascular Diseases and Internal Medicine, Mayo Clinic, 200 First St. SW, Rochester, MN 55905, USA.
Insights
Activated nuclear factor-kappaB (NF-kappaB) was found in pigs with experimental hypercholesterolemia, linked to reduced nitric oxide (NO) bioavailability and early atherosclerosis. This suggests NF-kappaB activation plays a role in the initial stages of this vascular disease.
Area of Science:
- Cardiovascular Research
- Molecular Biology
- Pathology
Background:
- Experimental hypercholesterolemia (HC) is associated with reduced nitric oxide (NO) bioavailability and cellular proliferation.
- Nuclear factor-kappaB (NF-kappaB) is implicated in inflammation, cellular proliferation, and potentially early atherosclerosis.
Purpose of the Study:
- To investigate the presence of activated NF-kappaB in the coronary vasculature of experimental hypercholesterolemia.
- To determine if activated NF-kappaB is associated with decreased NO bioavailability in this condition.
Main Methods:
- Pigs were fed either a hypercholesterolemic (HC) or normal diet for 10-12 weeks.
- Activated NF-kappaB was detected using monoclonal antibodies and Western blotting in coronary artery tissues.
- Endothelium-dependent vasorelaxation and nitric oxide (NO) bioavailability were assessed in vitro.
Main Results:
- Activated NF-kappaB was significantly present in the coronary vasculature of HC pigs compared to controls.
- The HC group showed increased activated NF-kappaB, decreased endothelial nitric oxide synthase (eNOS) protein, and impaired vasorelaxation.
- NF-kappaB was detected in both the nucleus and cytoplasm of intimal cells.
Conclusions:
- Activation of NF-kappaB is suggested to play a role in the early stages of atherosclerosis.
- The findings link NF-kappaB activation with reduced NO bioavailability in the coronary vasculature during hypercholesterolemia.
Background:
Experimental hypercholesterolemia (HC) is characterized by a decrease in nitric oxide (NO) bioavailability and cellular proliferation. Nuclear factor-kappaB (NF-kappaB) is a transcriptional factor which plays a coordinating role in inflammation and cellular proliferation and may be involved in early atherosclerosis. We examined whether activated NF-kappaB was present in experimental hypercholesterolemia in the coronary vasculature in association with a decrease in NO bioavailability.
Methods:
A total of 14 juvenile domestic crossbred pigs were placed on a HC diet and six pigs on a normal diet for 10-12 weeks. A monoclonal antibody to the activated form of the p65 subunit of NF-kappaB was used to detect immunoreactivity in coronary artery sections. Coronary tissue homogenates were analyzed for activated NF-kappaB and endothelial nitric oxide synthase (eNOS) using Western blotting. In vitro coronary endothelium-dependent relaxation was performed in response to bradykinin, as a measure of NO bioavailability.
Results:
Intimal staining for activated NF-kappaB was present in 12/14 HC pigs as compared with 0/6 controls (P<0.001). Confocal microscopy confirmed the presence of NF-kappaB in the nucleus of intimal cells although the majority of the staining was cytoplasmic. In the HC group, Western blotting revealed an increase in activated NF-kappaB in the vessel wall compared to the normal group, in association with a decrease in the presence of eNOS protein and an attenuated vasorelaxation response to bradykinin.
Conclusion:
This study suggests a potential role for activation of NF-kappaB, in association with a decrease in NO bioavailability, in the initial stages of atherosclerosis in the coronary vasculature.