Anti-Trypanosoma cruzi Activity of Metabolism Modifier Compounds

Chagas disease is caused by the protozoan parasite Trypanosoma cruzi and affects over 6 million people worldwide. Development of new drugs to treat this disease remains a priority since those currently available have variable efficacy and frequent adverse effects, especially during the long regimens required for treating the chronic stage of the disease. T. cruzi modulates the host cell-metabolism to accommodate the cell cytosol into a favorable growth environment and acquire nutrients for its multiplication. In this study we evaluated the specific anti-T. cruzi activity of nine bio-energetic modulator compounds. Notably, we identified that 17-DMAG, which targets the ATP-binding site of heat shock protein 90 (Hsp90), has a very high (sub-micromolar range) selective inhibition of the parasite growth. This inhibitory effect was also highly potent (IC50 = 0.27 μmol L−1) against the amastigote intracellular replicative stage of the parasite. Moreover, molecular docking results suggest that 17-DMAG may bind T. cruzi Hsp90 homologue Hsp83 with good affinity. Evaluation in a mouse model of chronic T. cruzi infection did not show parasite growth inhibition, highlighting the difficulties encountered when going from in vitro assays onto preclinical drug developmental stages

Novel purine chemotypes with activity against Plasmodium 2 falciparum and Trypanosoma cruzi

Malaria and Chagas disease, caused by Plasmodium spp. and Trypanosoma cruzi parasites, remain important global health problems. Available treatments for those diseases present several limitations, such as lack of efficacy, toxic side effects, and drug resistance. Thus, new drugs are urgently needed. The discovery of new drugs may be benefited by considering the significant biological differences between hosts and parasites. One of the most striking differences is found in the purine metabolism, because most of the parasites are incapable of de novo purine biosynthesis. Herein, we have analyzed the in vitro anti-P. falciparum and anti-T. cruzi activity of a collection of 81 purine derivatives and pyrimidine analogs. We firstly used a primary screening at three fixed concentrations (100, 10, and 1 µM) and progressed those compounds that kept the growth of the parasites < 30% at 100 µM to dose–response assays. Then, we performed two different cytotoxicity assays on Vero cells and human HepG2 cells. Finally, compounds specifically active against T. cruzi were tested against intracellular amastigote forms. Purines 33 (IC50 = 19.19 µM) and 76 (IC50 = 18.27 µM) were the most potent against P. falciparum. On the other hand, 6D (IC50 = 3.78 µM) and 34 (IC50 = 4.24 µM) were identified as hit purines against T. cruzi amastigotes. Moreover, an in silico docking study revealed that P. falciparum and T. cruzi hypoxanthine guanine phosphoribosyltransferase enzymes could be the potential targets of those compounds. Our study identified two novel, purine-based chemotypes that could be further optimized to generate potent and diversified anti-parasitic drugs against both parasites.SAF2016-76080-R (Spanish Ministry of Economy (AEI/FEDER, UE))PID2019-110810RB-I00 (Spanish Ministry of Science and Innovation)Generalitat of Catalonia Universities and Research Department, Spain (AGAUR; 2017SGR00924)Carlos III Health Institute (ISCIII)RICET Network for Cooperative Research in Tropical Diseases (ISCIII; RD12/0018/0010)Generalitat of Catalonia Department of Health (PERIS 2016–2010 SLT008/18/00132)Spanish Ministry of Education, Culture, and Sports (FPU grant ref. 14/00818)Spanish Ministry of Science, Innovation, and Universities through the “Centro de Excelencia Severo Ochoa 2019–2023” Program (CEX2018-000806-S)CERCA Progra

The Use of AlphaFold for in silico exploration of drug targets in the parasite Trypanosoma cruzi

Chagas disease is a devastating neglected disease caused by the parasite Trypanosoma cruzi, which affects millions of people worldwide. The two anti-parasitic drugs available, nifurtimox and benznidazole, have a good efficacy against the acute stage of the infection. But this is short, usually asymptomatic and often goes undiagnosed. Access to treatment is mostly achieved during the chronic stage, when the cardiac and/or digestive life-threatening symptoms manifest. Then, the efficacy of both drugs is diminished, and their long administration regimens involve frequently associated adverse effects that compromise treatment compliance. Therefore, the discovery of safer and more effective drugs is an urgent need. Despite its advantages over lately used phenotypic screening, target-based identification of new anti-parasitic molecules has been hampered by incomplete annotation and lack of structures of the parasite protein space. Presently, the AlphaFold Protein Structure Database is home to 19,036 protein models from T. cruzi, which could hold the key to not only describe new therapeutic approaches, but also shed light on molecular mechanisms of action for known compounds. In this proof-of-concept study, we screened the AlphaFold T. cruzi set of predicted protein models to find prospective targets for a pre-selected list of compounds with known anti-trypanosomal activity using docking-based inverse virtual screening. The best receptors (targets) for the most promising ligands were analyzed in detail to address molecular interactions and potential drugs' mode of action. The results provide insight into the mechanisms of action of the compounds and their targets, and pave the way for new strategies to finding novel compounds or optimize already existing ones

Identification of Trypanosoma cruzi Growth Inhibitors with Activity In Vivo within a Collection of Licensed Drugs

Chagas disease, caused by the parasite Trypanosoma cruzi (T. cruzi), affects more than six million people worldwide, with its greatest burden in Latin America. Available treatments present frequent toxicity and variable efficacy at the chronic phase of the infection, when the disease is usually diagnosed. Hence, development of new therapeutic strategies is urgent. Repositioning of licensed drugs stands as an attractive fast-track low-cost approach for the identification of safer and more effective chemotherapies. With this purpose we screened 32 licensed drugs for different indications against T. cruzi. We used a primary in vitro assay of Vero cells infection by T. cruzi. Five drugs showed potent activity rates against it (IC50 &lt; 4 µmol L−1), which were also specific (selectivity index &gt;15) with respect to host cells. T. cruzi inhibitory activity of four of them was confirmed by a secondary anti-parasitic assay based on NIH-3T3 cells. Then, we assessed toxicity to human HepG2 cells and anti-amastigote specific activity of those drugs progressed. Ultimately, atovaquone-proguanil, miltefosine, and verapamil were tested in a mouse model of acute T. cruzi infection. Miltefosine performance in vitro and in vivo encourages further investigating its use against T. cruzi

Development and Application of an Assay to Evaluate the Anti-Parasitic Effect of Humoral Responses against <i>Trypanosoma cruzi</i>

Mounting a balanced and robust humoral immune response is of utmost importance for reducing the infectivity of Trypanosoma cruzi. While the role of such a response in controlling the infection is well known, there is a lack of tools that can be used to quickly evaluate it. We developed a serum parasite inhibition assay (to evaluate changes in the parasite infection after exposing infective T. cruzi trypomastigotes to serum samples from infected patients). It is based on Vero cells as the hosts and the Tulahuen β-galactosidase parasite strain, genetically engineered to be quantifiable by spectrophotometry. In parallel, we developed an in-house ELISA to correlate the anti-T. cruzi antibody titres of the clinical samples with their observed anti-parasitic effect in the serum parasite inhibition assay. Serum samples from chronically T. cruzi-infected patients significantly inhibited parasite invasion in a titre-dependant manner, regardless of the patient’s clinical status, compared to samples from the non-infected controls. In addition, there was a clear correlation between the reactivity of the samples to the whole-parasite lysates by ELISA and the inhibitory effect. The results of this work confirm the previously described anti-parasitic effect of the serum of individuals exposed to T. cruzi and present a framework for its large-scale evaluation in further studies. The serum parasite inhibition assay represents a reproducible way to evaluate the intensity and anti-parasitic effect of humoral responses against T. cruzi, which could be applied to the evaluation of candidate antigens/epitopes in the design of Chagas disease vaccine candidates

Anti-Trypanosoma cruzi activity of alkaloids isolated from Habranthus brachyandrus (Amaryllidaceae) from Argentina

Chagas disease, caused by the parasite Trypanosoma cruzi, affects over six million people worldwide, mainly in Latin American countries. Currently available drugs have variable efficacy in the chronic phase and significant side effects, so there is an urgent need for safer chemotherapeutic treatments. Natural products provide privileged structures that could serve as templates for the synthesis of new drugs. Among them, Amaryllidaceae plants have proved to be a potential natural source of therapeutical agents due to their rich diversity in alkaloids.To identify alkaloids with anti-T. cruzi activity from Habranthus brachyandrus (Baker) Sealy (Amaryllidaceae, subfamily Amaryllidoideae) collected in Argentina.An H. brachyandrus alkaloid extract was tested against T. cruzi, and its cytotoxicity profile was evaluated against two mammalian cell lines to ascertain its selectivity against the parasite and potential liver toxicity. It was also assessed by a stage-specific anti-amastigote assay and analysed by GC/MS to determine its alkaloid profile. The isolated alkaloids were also tested using the aforementioned assays.The extract showed high and specific activity against T. cruzi. The alkaloids lycoramine, galanthindole, 8-O-demethylmaritidine, 8-O-demethylhomolycorine, nerinine, trisphaeridine, deoxytazettine, and tazettamide were identified by means of GC-MS. In addition, hippeastidine (also named aulicine), tazzetine, ismine, and 3-epimacronine were isolated. The alkaloid ismine was specifically active against the parasite and had low toxicity against HepG2 cells, but did not show anti-amastigote activity.The extract had specific anti-T. cruzi activity and the isolated alkaloid ismine was partially responsible of it. These results encourage further exploration of H. brachyandrus alkaloids in search of novel starting points for Chagas disease drug development.Copyright © 2022. Published by Elsevier GmbH

Appropriateness of antiplatelet therapy for primary and secondary cardio- and cerebrovascular prevention in acutely hospitalized older people

Aims: Antiplatelet therapy is recommended for the secondary prevention of cardio- and cerebrovascular disease, but for primary prevention it is advised only in patients at very high risk. With this background, this study aims to assess the appropriateness of antiplatelet therapy in acutely hospitalized older people according to their risk profile. Methods: Data were obtained from the REPOSI register held in Italian and Spanish internal medicine and geriatric wards in 2012 and 2014. Hospitalized patients aged ≥65 assessable at discharge were selected. Appropriateness of the antiplatelet therapy was evaluated according to their primary or secondary cardiovascular prevention profiles. Results: Of 2535 enrolled patients, 2199 were assessable at discharge. Overall 959 (43.6%, 95% CI 41.5–45.7) were prescribed an antiplatelet drug, aspirin being the most frequently chosen. Among patients prescribed for primary prevention, just over half were inappropriately prescribed (52.1%), being mainly overprescribed (155/209 patients, 74.2%). On the other hand, there was also a high rate of inappropriate underprescription in the context of secondary prevention (222/726 patients, 30.6%, 95% CI 27.3–34.0%). Conclusions: This study carried out in acutely hospitalized older people shows a high degree of inappropriate prescription among patients prescribed with antiplatelets for primary prevention, mainly due to overprescription. Further, a large proportion of patients who had had overt cardio- or cerebrovascular disease were underprescribed, in spite of the established benefits of antiplatelet drugs in the context of secondary prevention

Prognostic value of degree and types of anaemia on clinical outcomes for hospitalised older patients

Study objective This study investigated in a large sample of in-patients the impact of mild-moderate-severe anaemia on clinical outcomes such as in-hospital mortality, re-admission, and death within three months after discharge. Methods A prospective multicentre observational study, involving older people admitted to 87 internal medicine and geriatric wards, was done in Italy between 2010 and 2012. The main clinical/laboratory data were obtained on admission and discharge. Based on haemoglobin (Hb), subjects were classified in three groups: group 1 with normal Hb, (reference group), group 2 with mildly reduced Hb (10.0–11.9 g/dL in women; 10.0–12.9 g/dL in men) and group 3 with moderately-severely reduced Hb (<10 g/dL in women and men). Results Patients (2678; mean age 79.2 ± 7.4 y) with anaemia (54.7%) were older, with greater functional impairment and more comorbidity. Multivariable analysis showed that mild but not moderate-severe anaemia was associated with a higher risk of hospital re-admission within three months (group 2: OR = 1.62; 95%CI 1.21–2.17). Anaemia failed to predict in-hospital mortality, while a higher risk of dying within three months was associated with the degree of Hb reduction on admission (group 2: OR = 1.82;95%CI 1.25–2.67; group 3: OR = 2.78;95%CI 1.82–4.26) and discharge (group 2: OR = 2.37;95%CI 1.48–3.93; group 3: OR = 3.70;95%CI 2.14–6.52). Normocytic and macrocytic, but not microcytic anaemia, were associated with adverse clinical outcomes. Conclusions Mild anaemia predicted hospital re-admission of older in-patients, while three-month mortality risk increased proportionally with anaemia severity. Type and severity of anaemia affected hospital re-admission and mortality, the worst prognosis being associated with normocytic and macrocytic anaemia

Risk factors for three-month mortality after discharge in a cohort of non-oncologic hospitalized elderly patients: Results from the REPOSI study

Background: Short-term prognosis, e.g. mortality at three months, has many important implications in planning the overall management of patients, particularly non-oncologic patients in order to avoid futile practices. The aims of this study were: i) to investigate the risk of three-month mortality after discharge from internal medicine and geriatric wards of non-oncologic patients with at least one of the following conditions: permanent bedridden status during the hospital stay; severely reduced kidney function; hypoalbuminemia; hospital admissions in the previous six months; severe dementia; ii) to establish the absolute risk difference of three-month mortality of bedridden compared to non-bedridden patients. Methods: This prospective cohort study was run in 102 Italian internal medicine and geriatric hospital wards. The sample included all patients with three-months follow-up data. Bedridden condition was defined as the inability to walk or stand upright during the whole hospital stay. The following parameters were also recorded: estimated GFR <= 29 mL/min/1.73 m(2); severe dementia; albuminemia << 2.5 g/dL; hospital admissions in the six months before the index admission. Results: Of 3915 patients eligible for the analysis, three-month follow-up were available for 2058, who were included in the study. Bedridden patients were 112 and the absolute risk difference of mortality at three months was 0.13 (CI 95% 0.08-0.19, p << 0.0001). Logistic regression analysis also adjusted for age, sex, number of drugs and comorbidity index found that bedridden condition (OR 2.10, CI 95% 1.12-3.94), severely reduced kidney function (OR 2.27, CI 95% 1.22-4.21), hospital admission in the previous six months (OR 1.96, CI 95% 1.22-3.14), severe dementia (with total or severe physical dependence) (OR 4.16, CI 95% 2.39-7.25) and hypoalbuminemia (OR 2.47, CI 95% 1.12-5.44) were significantly associated with higher risk of three-month mortality. Conclusions: Bedridden status, severely reduced kidney function, recent hospital admissions, severe dementia and hypoalbuminemia were associated with higher risk of three-month mortality in non-oncologic patients after discharge from internal medicine and geriatric hospital wards