Activated nuclear factor-κB is present in the coronary vasculature in experimental hypercholesterolemia

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Background : Experimental hypercholesterolemia (HC) is characterized by a decrease in nitric oxide (NO) bioavailability and cellular proliferation. Nuclear factor-κB (NF-κB) 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-κB 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-κB was used to detect immunoreactivity in coronary artery sections. Coronary tissue homogenates were analyzed for activated NF-κB 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-κB was present in 12/14 HC pigs as compared with 0/6 controls ( P<0.001). Confocal microscopy confirmed the presence of NF-κB 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-κB 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-κB, in association with a decrease in NO bioavailability, in the initial stages of atherosclerosis in the coronary vasculature.