https://videoconf-colibri.zoom.us/j/87030273126?pwd=Z01wZkhYRU0ySE8rL1V0aHlVb0lnZz09
Meeting ID: 870 3027 3126
Password: 289600
Organizing committee
CCI Drug Discovery and Drug Resistance – Pedro Cravo
RG Vector Borne Diseases – Ana Paula Arez
Programme
10.00h – 13.00h (coffee break 11h – 11h30)
10.00h – 10.15h: Pedro Cravo.
Global Health and Tropical Medicine (GHTM), Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa, Portugal
Welcome and Introductory note.
10.15h – 10.35h: Teresa Carvalho
Department of Microbiology, Anatomy, Physiology and Pharmacology, La Trobe University, Bundoora, Victoria 3086, Australia
Title: Host-directed malaria therapies: when targeting host red blood cell proteins compromises Plasmodium falciparum survival
Abstract: The development of antimalarial drug resistance is an ongoing problem threatening progress towards malaria elimination, and antimalarial treatments are urgently needed for drug-resistant malaria infections. Host-directed therapies (HDT) represent an attractive strategy for the development of new antimalarials with untapped targets and low propensity for resistance. In addition, drug repurposing in the context of HDT can lead to a substantial decrease in the time and resources required to develop novel antimalarials. Host BCL-XL is a target in anti-cancer therapy and is essential for the development of numerous intracellular pathogens. We hypothesised that red blood cell (RBC) BCL-XL is essential for Plasmodium development and tested this hypothesis by using six BCL-XL inhibitors, including one FDA approved compound. All BCL-xL inhibitors tested impaired proliferation of P. falciparum 3D7 parasites in vitro at low micromolar or sub-micromolar concentrations. Western blot analysis of infected cell fractions and immunofluorescence microscopy assays revealed that host BCLxL is relocated from the RBC cytoplasm to the vicinity of the parasite upon infection. Further, immunoprecipitation of BCL-XL coupled with mass spectrometry analysis identified that BCLXL forms unique molecular complexes with human μ-calpain in uninfected RBCs, and with human SHOC2 in infected RBCs. These results open interesting perspectives for the development of host-directed antimalarial therapies and drug repurposing efforts.
10.35h – 11.05h: Ana Paula Arez
Global Health and Tropical Medicine (GHTM), Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa, Portugal
Title: Pyruvate kinase deficiency protective effect against malaria infection – does the red blood cell-specific glycolytic intermediate 2,3-diphosphoglycerate (2,3-DPG) have a role?
Abstract: Interaction mechanisms of malaria parasite and its host red blood cell (RBC) may provide targets for new antimalarial approaches. Pyruvate kinase deficiency (PKD) was associated with resistance to malaria in experimental models and population studies. Two major PKD-cell disorders are the decrease in ATP and the increase in 2,3-diphosphoglycerate (2,3-DPG). High levels of 2,3-DPG, only present in mammalian RBC, has an inhibitory effect on glycolysis and its accumulation may be harmful to the parasite and be involved in the mechanism of protection provided by PKD. We examined the effect of a synthetic form of this metabolite on the Plasmodium falciparum intraerythrocytic developmental cycle and observed an impairment of parasite growth and maturation as significant lower progeny emerged from parasites that were submitted to 2,3-DPG. The addition of the compound had no major effect on the RBC, but instead the metabolic profile of infected and treated RBC was closer to the one from non-infected cells than the one from infected and untreated RBC.
Funding: Fundação para a Ciência e Tecnologia projects PTDC_BIA-CEL_28456_2017 and GHTM – UID/04413/2020.
11.05h – 11.35h: Coffee Break
11.35h – 12.05h: Sandra Antunes
Global Health and Tropical Medicine (GHTM), Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa, Portugal
Title: Proteomics studies on Rhipicephalus bursa- Babesia ovis towards the development of anti-tick vaccines
Abstract: The (re-) emergence of tick-borne diseases (TBD) is now a recognized threat in human and animal health. Understanding the paradigm pathogen-vector remains an intricate issue, since in these interplays a complex network of molecular interactions take place. Studies focusing these relationships might identify key molecular steps that can be targeted to reduce vector competence and control disease. The discovery of relevant molecules in tick-pathogen interface is essential for the development of promising alternative (to acaricides) TBD control methods, such as vaccination. The model Rhipicephalus bursa – Babesia ovis has been established and used to contribute for the identification of such molecules.
12.05h – 12.25h: Margarida Saraiva
i3S – Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Portugal
Title: Learning from Mycobacterium tuberculosis to develop host-directed therapies to tuberculosis.
Abstract: Tuberculosis (TB) is caused by bacteria belonging to the Mycobacterium tuberculosis complex, which includes nine phylogenetically distinct lineages associated with specific geographic regions in the world. Recent evidence supports a functional relevance to the genetic diversity of TB-causing bacteria, in what regards the triggering of the immune response and important clinical features of TB. Our group combines human and mouse systems with clinical isolates of M. tuberculosis as tools to mimic the genetic diversity of this pathogen and investigate host-pathogen interactions in TB. Using this approach, we demonstrated that innate immune responses are deeply modulated by M. tuberculosis genetic diversity. We showed that M. tuberculosis strains isolated from patients with severe TB escape protective macrophage cytosolic recognition, resulting in reduced IL-1β production. Building upon these findings we are now investigating how the differential modulation of the inflammasome by distinct M. tuberculosis isolates relates with the glycolytic reprograming of the macrophage; and how the manipulation of early IL-1 responses impacts the in vivo (mouse) outcome of infection. We are also exploring host-pathogen interactions during infections with M. africanum to reveal targetable host pathways. Collectively, our studies link pathogen genomes, immune phenotypes and clinical outcomes of TB in the search for host immune pathways and bacterial signatures to be targeted in the design of novel TB interventions.
12.25h – 12.45h: Elsa Anes
Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Portugal
Title: Manipulation of protease inhibitors for developing therapeutic strategies against Mycobacterium tuberculosis infection
Abstract: Despite the available antibiotics, tuberculosis (TB) is considered a global threat mostly due to co-infection with human immunodeficiency virus (HIV), to the emergence of drug resistant strains and lack of an effective vaccine. It is urgent to develop new therapeutic strategies to fight TB. Host-directed strategies could be exploited to boost the host immune responses both for innate bacteria killing and for future vaccination strategies. We showed that Mtb manipulates their host cells by decreasing the expression and activity of lysosomal cathepsins. Consequently, Mtb survives and even replicates inside macrophages concomitant with a poor priming of the adaptive immune responses. We decided to overcome this pathogen induced response targeting cathepsin protease inhibitors (1) by repurposing a HIV protease inhibitor, saquinavir, that we found to increase the activity of cathepsins in the endocytic pathway and, (2) by targeting cystatins the natural inhibitors of cathepsins. We found that in both situations an improved intracellular killing of Mtb was observed as well as an increased CD4+ T-Lymphocyte proliferation along with enhanced IFNγ secretion. This approach suggests a novel avenue for the development of potential alternative therapeutic strategies to current antimicrobials against this infectious disease.
Keywords: Cystatins, Cathepsins, Saquinavir, Tuberculosis, Host-directed therapies
Funding: This study was supported by grants from National Foundation for Science, FCT Fundação para a Ciência e Tecnologia – Portugal, PTDC/SAU-INF/28182/2017 to EA.
12.45h – 13.00h: Concluding Remarks
