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Degree

Doctor of Philosophy, Ohio State University, Pharmacy, 2004.

Abstract

Atherogenesis shares many features with inflammatory and immunal reactions. Bacterial endotoxin (LPS), together with T-lymphocytes cytokine interferon-gamma (IFNγ), causes inflammation and immune response. Because of its strategic anatomic position, endothelial cells are a primary target for injury and cardiovascular risk factors. A simple method for isolating and culturing mouse aortic endothelial cells (MAEC) was developed for studying the endothelial injury and activation by these stimuli in vitro (Section I). The effects of LPS and IFN, in the absence and presence of hypercholesterolemia, a traditional risk factor for atherosclerosis, on endothelial function and pro-inflammatory gene expression in vivo were also studied (Section II). We found that LPS and IFN synergistically activated MAEC by upregulating pro-inflammatory genes, such as inducible nitric oxide synthase and vascular cell adhesion molecule-1. Several signal transduction pathways, such as the Janus kinase/signal transducer and activator of transducer-1 (STAT1), the p38 mitogen-activated protein kinase, and the protein kinase A pathways, were involved in this regulation. Other effects of LPS included inducing the production of superoxide anion and hydrogen peroxide by MAEC. These reactive oxygen species, especially oxidized low-density lipoprotein cholesterol, caused MAEC injury, DNA breakage and gene expression. The in vivo effects of inflammation in endothelial dysfunction and atherogenesis were studied using a mouse model (C57BL/6) on an atherogenic diet. A single low dose of LPS (1.0 mg/kg, intraperitoneal injection) caused an impairment of endothelial-dependent vasorelaxation in response to acetylcholine in these mice but not their normal diet fed littermates. Endothelial-independent vasorelaxation remained unaffected. Chronic treatment with LPS (once a week for 12 weeks) or 16-week of the atherogenic diet each caused endothelial dysfunction. A more significant effect was observed with the combination of a low dose of LPS (0.5 mg/kg) and the atherogenic diet. The impairment of endothelial function by the atherogenic diet was lesser in STAT1 knockout mice. Overall, our results presented here suggest that multiple factors, such as inflammation, oxidation, and hypercholesterolemia, are involved in endothelial cell activation and dysfunction. These mechanistic insights of endothelial biology will provide new therapy for the cardiovascular disease, especially atherosclerosis.

Subject Headings

Health Sciences, Pharmacy

Keywords

LPS; IFNγ; MAEC; ENDOTHELIAL; STAT1; iNOS; atherogenic diet

Advisor

Dale G Hoyt

Pages

475p.

Document number: osu1092663493
Permalink: http://rave.ohiolink.edu/etdc/view?acc_num=osu1092663493

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