Drug repurposing of bioenergetic modulators: use in treatment and vaccination of protozoan parasitic diseases /
- Autores: Alba Martínez Flórez
- Directores de la Tesis: Jordi Alberola (dir. tes.), Alhelí Rodríguez Cortés (codir. tes.)
- Lectura: En la Universitat Autònoma de Barcelona ( España ) en 2017
- Idioma: español
- Tribunal Calificador de la Tesis: Montserrat Gállego Culleré (presid.), Fernando de Mora Pérez (secret.), Xavier Fernández Busquets (voc.)
- Programa de doctorado: Programa Oficial de Doctorado en Farmacología
- Materias:
- Enlaces
- Resumen
Leishmaniases, African and American trypanosomiases and malaria are parasitic diseases that constitute a major global health problem. The increasing number of drug-resistances to their current treatments, toxicity cases and the health assistance often required for their administration, makes it urgently necessary to develop efficient vaccines for humans and new affordable therapies, easy to apply and resistant to harsh storage conditions. Due to the fact that these diseases share similar metabolic requirements with better studied diseases, we chose drug repurposing as a potentially effective approach against them. With this purpose, six different compounds used in anti-cancer research —dichloroacetate (DCA), 3-bromopyruvate (3BP), 2-deoxy-D-glucose (2DG), lonidamine (LND), metformin (MET), and sirolimus (SIR)— were selected according to their ability to modulate energy production and proliferation related metabolic pathways. The aim of this study was to validate the suitability of these bioenergetics modulators for the management of visceral leishmaniasis, malaria and African and American trypanosomiasis as a treatment, or as a preventive tool by enhancing the protective power of a vaccine against L. infantum.
The effectiveness of these compounds was first evaluated on in vitro models of each parasite ―Chagas disease (Trypanosoma cruzi), human African trypanosomiasis (Trypanosoma brucei), visceral leishmaniasis (Leishmania infantum) and malaria (Plasmodium falciparum)―. L. infantum intracellular amastigote growth was dose-dependently reduced by 3BP (IC50 = 17.19 µM) and DCA (IC50 = 631.5 µM). In the T. brucei in vitro model all the tested compounds, with the exception of 2DG, affected parasite survival with IC50 values of 1.24 mM for DCA, 76.57 µM for 3BP, 26.76 µM for LND, 2.14 µM for SIR, and 17.30 mM for MET. In the case of T. cruzi, DCA, 3BP, 2DG, LND, and MET showed parasite-killing activity with IC50 values of 27.07 mM, 27.63 µM, 7.27 mM, 78.37 µM, and 18.48 mM, respectively. For P. falciparum DCA (IC50 = 5.39 mM), 2DG (IC50 = 4.19 mM), LND (IC50 = 209.13 µM), MET (IC50 = 1.32 mM), and SIR (IC50 = 2.50 µM), showed anti-plasmodial activity. These results reinforce the hypothesis that drugs with proven efficacy in the treatment of cancer by interfering with energy production might be useful in treating parasitic diseases and provide new opportunities for their repurposing. However, when effective compounds in the in vitro approach were administered to the in vivo rodent models of these diseases, none of them contributed to disease management or parasite load control. Immunological analysis in the VL hamster model revealed a significant downregulation of immune-activation in infected animals treated with DCA and 3BP, which may also contribute to treatment failure.
In the last chapter of this work, the suitability of SIR as an immunomodulatory compound to boost the activity of a preventive vaccine against VL was analyzed. SIR is an already marketed compound that has been described to boost immune protection against different disease models. In our study, Syrian hamsters were treated with SIR concomitantly with the administration of a plasmid DNA vaccine carrying the Leishmania genes LACK, TRYP, PAPLE22 and KMPII, and the subsequent response towards a L. infantum challenge was studied. Our results show that the DNA vaccine itself efficiently reduced the burden of parasites in skin (P = 0.0004) and lymph nodes (P = 0.0452), which was potentiated by SIR administration by also inducing parasitological protection in the spleen (P = 0.0004). The study of immune markers in spleen suggests that lower production of IFN-γ and the concurrent increase of FoxP3+ expression may be responsible for the protection mediated by the DNA vaccine that was potentiated by SIR.
