Molecular Mechanisms in T. cruzi Cardiomyopathy in AIDS

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DESCRIPTION (provided by applicant): Chagas' disease is caused by the protozoan parasite T. cruzi and is now recognized as an emerging HIV/AIDS-related, opportunistic infection. Subsequent to immunosuppression there is reactivation of dormant organisms leading to myocarditis and necrotizing encephalitis. Since HIV-infected patients receiving HAART live for many years there is the likelihood that there will be repeated episodes of reactivation as their immune status waxes and wanes. Hence, progressive myocarditis and cardiovascular remodeling and chronic cardiomyopathy will likely develop in a more rapid fashion. In this application we have defined ventricular remodeling as changes in structure and function following myocardial damage together with characteristic molecular changes. These changes are the result of inflammation and/or necrosis. T. cruzi infection of the myocardium results in a dilated cardiomyopathy. Our overall objective is to examine some of the important signaling pathways involved in cardiac remodeling as a consequence of the T. cruzi infection. We plan to examine the consequences of T. cruzi-infection on cyclins in vitro, Our investigations clearly indicate that T. cruzi-induced ERK activation modulates the expression and/or activity of cyclins, which function as mediators of cellular proliferation and differentiation. Cyclins are responsible for remodeling in the cardiovascular system. Therefore, the kinetics of the expression of cyclins in infected cultured cells and co-culture systems. Since we have demonstrated that T. cruzi induces expression of cyclin D1, we will determine the molecular mechanisms involved in regulation of cyclin D 1 promoter activation in cardiac fibroblasts employing transient transfection/promoter assays. We plan to determine the consequence of T. cruzi infection on cyclins in mouse models of chagasic heart disease on. During acute T. cruzi infection there is activation of ERK, transcription factors AP-1 and NF-kB and increased expression of cyclin D 1 in the myocardium. Therefore, in the mouse model of Chagas' disease the kinetics of expression of cell cycle regulatory proteins in the cells of the myocardium of T. cruzi-infected mice will be determined and correlated with progression of cardiomyopathy. The mechanisms underlying the alterations in these proteins in the myocardium will be investigated by a variety of techniques including immune complex assays and cell proliferation experiments. The contribution of cyclin D 1 in cardiovascular remodeling will be investigated utilizing mouse models including cyclin D1 null mice and mice in which NF-r.d3 and ET-1 have been selectively deleted from cardiac myocytes. These studies will lead to a better understanding of cardiac remodeling in chagasic cardiomyopathy, an emerging opportunistic infection in AIDS. In addition, it will provide potential targets of adjunctive therapy.