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| Author(s): |
Juliana Morais Alvim
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Faculdade de Medicina (FM/SBD) |
| Defense date: | 2019-11-01 |
| Examining board members: |
Paulo Caleb Júnior de Lima Santos;
Niels Olsen Saraiva Câmara;
Sergio Schenkman
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| Advisor: | Alexandre da Costa Pereira |
| Abstract | |
Chagas Disease is caused by the parasite Trypanosoma cruzi and is considered by the World Health Organization to be a neglected endemic tropical disease in Latin America. The disease has an acute phase that is difficult to diagnose, but with high chances of cure when treated, and a chronic phase that may be asymptomatic or with cardiac and/or gastrointestinal manifestations. About 30% of patients in the chronic phase develop cardiac manifestations of the disease, which leads to a worse prognosis when compared to other heart disease. There is no effective treatment for this phase of the disease and there is a large gap in the knowledge of the parasite-host relationship in both the chronic phase and cardiac tissue. Thus, the understanding of molecular mechanisms of response to infection that are used for parasitic replication in cardiac cells becomes essential. The aim of this study was to evaluate the modulation of the mTOR pathway in cardiomyocytes after T. cruzi infection. It is described in the literature that the parasite may influence the activation of this pathway in the cell after infection and that this mechanism is related to cellular effects that may or may not be beneficial for infection. These modulations appear to be dependent on cell type and parasite stage. In this sense, the present work performed the modulation of the mTOR pathway in hiPSC-derived cardiomyocytes using Rapamycin, an mTORC1 inhibitor. Through protein expression, we verified that there is activation of mTORC1 after infection (24 hpi) and that inhibition of this complex using Rapamycin decreases parasitic replication (48 hpi). This change is accompanied by an increase in oxygen consumption rate (OCR), especially 48 hpi, and Rapamycin treatment was able to revert OCR to values similar to the control. The number of mitochondria was assessed to determine whether there was correlation with the increase in OCR, but this amount is lower than the control in both infected and infected and treated groups. Using a mitophagy inducer (CCCP) it has been shown that this mechanism occurs after infection, but the decrease in replication assessed with Rapamycin is independent of mitophagy. Evaluating the parasite escape dynamics for the cytoplasm it was possible to notice that the effect of rapamycin is due to increasing the retention time of the parasites in the parasitophorous vacuole, thus delaying the multiplication time. Thus, it can be concluded that inhibition of mTORC1 generates effects on cardiomyocytes that lead to decreased parasitic replication independently of mitochondrial biogenesis or mitophagy, but acting on the escape dynamics of parasites to the cytoplasm (AU) | |
| FAPESP's process: | 16/25845-1 - Evaluation of the importance of glycolytic pathway, oxidative stress and fatty acid synthesis in the infection of cardiomyocytes by Trypanosoma cruzi |
| Grantee: | Juliana Morais Alvim |
| Support Opportunities: | Scholarships in Brazil - Master |