Role of Lipoproteins in Chagasic heart disease

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DESCRIPTION (provided by applicant): Chagas disease, caused by an intracellular parasite Trypanosoma cruzi, is a major public health problem with significant social and economic implications in most Latin American countries and among immigrant populations in developing countries, and is responsible for millions of deaths annually. Chagasic heart disease is characterized by myocarditis associated with prominent fibrotic scarring, cardiac hypertrophy, arrhythmia, cardiomyopathy, heart failure and secondary thromboembolism. Mortality due to cardiovascular disease is increasing in the most developed countries of South and Central America with the change to a high fat "western" diet. We demonstrated that elevated cholesterol increased the rate of T. cruzi invasion and that this parasite utilizes LDLr to invade host cells. Parasite invasion was associated with a significant increase in the levels of LDL in organs such as heart and liver. Immunofluorescence analysis demonstrated an accumulation of LDL around parasites in the myocardium of infected mice. LDL, HDL and total cholesterol levels of hearts of infected mice were significantly increased compared to the hearts of uninfected mice. Acute infection caused myocarditis, hepatomegaly, lipolysis, impaired serum lipid levels, and elevated tissue/organ cholesterol. Serum lipoproteins such as LDL, very Low Density Lipoprotein (VLDL) and HDL likely play a major role in the progression of Chagasic heart disease as parasites have high affinity for lipoproteins and causes influx of these lipoproteins into cells during invasion. The accumulated lipoproteins may undergo oxidation and responsible for the development of lipotoxicity, oxidative stress, inflammation and cell death, and contribute to the development of cardiomyopathy during T. cruzi infection. This proposal explores the possible correlation between serum lipids, diet and the development of Chagasic heart disease which is a new area of investigation. Understanding the factors responsible for chronic Chagasic cardiomyopathy is critical in order to develop new methods to prevent the progression of Chagasic heart disease. This is especially important as the epidemic of obesity, diabetes and dyslipidemia in Chagas endemic regions has the potential for significant interactions with this pathogen, thus altering th normal pathogenic process. PUBLIC HEALTH RELEVANCE: Low Density Lipoprotein (LDL) and cholesterol play a major role in the progression of Chagasic heart disease. Chagasic heart disease is characterized by myocarditis associated with prominent fibrotic scarring, cardiac hypertrophy, arrhythmia, cardiomyopathy, heart failure and secondary thromboembolism, and is due to infection with Trypanosoma cruzi. It is a major public health problem with significant social and economic implications in Latin and South America as well as among immigrants to the USA. It is estimated to cause 50,000 deaths annually. With changes in the diet of developing countries in South and Central America there has been an epidemic of obesity, diabetes and dyslipidemia. T. cruzi utilizes LDL receptors for invasion and infection results in accumulation of LDL and cholesterol in cells/tissues, contributing to the pathogenesis of cardiomyopathy. The studies proposed in this application will significantly improve our understanding of the interaction between lipoproteins and this cardiomyopathy, which offers the best chance for early intervention strategies aimed at preventing this devastating heart disease.