Human infection by the parasite Trypanosoma cruzi leads to inflammatory cardiomyopathy (Chagas disease) which is the leading infectious cause of heart failure in Latin America. The incidence of Chagas disease is increasing worldwide through the migration of chronically infected people from endemic areas. The mechanisms by which the parasite causes inflammation and fibrosis of host tissues are multifactorial and incompletely understood. The focus of this proposal is the parasite protein cyclophilin 19 (Cyp19), a peptidyl-prolyl isomerase, which is expressed and secreted by all lifecycle stages of the parasite including the two keys stages that cause human disease. Our work has found that Cyp19 binds to human CD147 (aka, extracellular matrix metalloprotease inducer; EMMPRIN), a ubiquitous cell-surface signaling protein implicated in multiple hyper-inflammatory states. Engagement of CD147 by Cyp19 leads to the production of matrix metalloproteases analogous to the well-documented action of extracellular human cyclophilin A (a structural and functional human homologue of Cyp19) induced inflammation in a variety of human pathologic conditions including cardiac disease. Our hypothesis is that during parasite infection released Cyp19 acts both locally in tissues and systemically as a potent inducer of host tissue inflammation. This is relevant to the inflammation leading to cardiac fibrosis and the development of Chagas cardiomyopathy. The experiments outlined in this exploratory project are designed to test this hypothesis. In the first aim we will interrogate the interaction between parasite Cyp19 and human CD147 using purified Cyp19 and inactive enzyme mutants to test whether Cyp19 enzymatic activity is essential for this activation. Host cell lines engineered to lack expression of CD147 will be used to test the specificity of the induction of inflammation on CD147 and in parasite infection studies to understand the influence of CD147 on parasite infectivity and intracellular growth. Parasites lines engineered to express diminished Cyp19 will be used in host cell infection studies to test the effect of variable amounts of Cyp19, in the context of the parasite, on host infection and the induction of inflammation in CD147-dependent and ?independent conditions. In the second aim we will determine the role of Cyp19 in the induction of tissue inflammation in a mouse model of infection. The effect of wildtype and enzymatically inactive Cyp19 proteins will be used to treat mice to determine if Cyp19 alone, in the absence of parasite infection, can induce tissue inflammation. Infection of mice with wildtype and Cyp19-deficient parasite lines will be compared for levels of parasitemia, induction of cardiac fibrosis and overall mortality. At the conclusion of this project we will understand whether Cyp19 contributes to T. cruzi infection and tissue pathogenesis and the results will provide the groundwork for further mechanistic studies on this pathologic process and the development of small molecule inhibitors for the potential treatment Chagas heart disease.
Human infection by the parasite Trypanosoma cruzi is the leading infectious cause of heart failure in Latin America. In this proposal we will investigate the contribution of a secreted parasite protein in the inflammation of host tissue that leads to heart disease. This work could provide the platform for the development of treatments and vaccines for this infection and the prevention of parasite-induced heart failure.
| Varikuti, Sanjay; Jha, Bijay Kumar; Volpedo, Greta et al. (2018) Host-Directed Drug Therapies for Neglected Tropical Diseases Caused by Protozoan Parasites. Front Microbiol 9:2655 |
