Abstract P407: Role Of Cyclic AMP During The Intracellular Infection Cycle Of Trypanosoma Cruzi

2021 ◽  
Vol 129 (Suppl_1) ◽  
Author(s):  
Daniel E Velez-Ramirez ◽  
Michelle Shimogawa ◽  
Kent Hill
Keyword(s):  
Trypanosoma Cruzi ◽  
Chagas Disease ◽  
Host Cells ◽  
Camp Signaling ◽  
Host Immune System ◽  
Infection Cycle ◽  
Tropical Regions ◽  
Host Environment ◽  
Intracellular Infection

Trypanosoma cruzi is the causative agent of Chagas disease, a vector-borne disease. In the 1990s the distribution of the vector, a hematophagous triatomine, and consequently the parasite, was from the southeast tropical regions of Mexico to South America. Now, global warming is causing this distribution to expand to northern territories in Mexico, reaching southern parts of US, in which up to 300,000 people are affected. Furthermore, an increase in chronically-infected immigrants to the US makes Chagas disease a matter of Pan-American public health that it should be addressed by all the America countries. Chagas disease manifests clinically as cardiovascular disease, characterized by hypertrophy of heart, esophagus and colon. Congestive heart failure is the main cause of death (58%) in Chagas patients, whereas cardiac arrhythmias and unexpected deaths add another 36%. A major cause of heart pathology in Chagas disease damage is caused by the host immune system, as it attacks chronically infected tissue. Therefore, pathology of the disease is a direct consequence of the ability of the parasite to invade host cells, so it can establish chronic infection. To achieve this, T. cruzi must sense and adapt to the host environment, but the underlying mechanisms are poorly understood. In particular, parasite signaling pathways used to sense and transduce signals from the host environment are most completely unknown. Our lab studies cAMP signaling in trypanosome parasites and several lines of evidence suggest T. cruzi cAMP signaling is important for host cell invasion, differentiation and persistent infection, which in turn underlies heart tissue pathology of Chagas disease. A transcriptome analysis revealed that mRNA of proteins involved in cAMP metabolism, i.e. adenylate cyclases and phosphodiesterases, are either upregulated or downregulated during the intracellular infection cycle. In fact, the phosphodiesterases have flagellar homologs with known cAMP signaling functions in a related parasite. This suggests that cAMP might fluctuate during as T. cruzi invades, differentiates, and multiplies inside the host cells. We have implemented a cAMP FRET sensor to monitor cAMP levels in trypanosomes to understand the role of cAMP in T. cruzi pathogenesis.

scholarly journals Is Antibody-Dependent Enhancement of Trypanosoma cruzi Infection Contributing to Congenital/Neonatal Chagas Disease?

2021 ◽  
Vol 12 ◽  
Author(s):  
Yves Carlier ◽  
Carine Truyens ◽  
Eric Muraille
Keyword(s):  
Trypanosoma Cruzi ◽  
Pregnant Women ◽  
Chagas Disease ◽  
Viral Infections ◽  
Neonatal Morbidity ◽  
Host Cells ◽  
Antibody Dependent Enhancement ◽  
Severe Reduction ◽  
Cruzi Infection

The newborns of women infected with the parasite Trypanosoma cruzi (the agent of Chagas disease) can be infected either before birth (congenitally), or after birth (as e.g., by vector route). Congenital Chagas disease can induce high levels of neonatal morbidity and mortality. Parasite-infected pregnant women transmit antibodies to their fetus. Antibodies, by opsonizing parasites, can promote phagocytosis and killing of T. cruzi by cells expressing FcγR, on the mandatory condition that such cells are sufficiently activated in an inflammatory context. Antibody-dependent enhancement (ADE) is a mechanism well described in viral infections, by which antibodies enhance entry of infectious agents into host cells by exploiting the phagocytic FcγR pathway. Previously reported Chagas disease studies highlighted a severe reduction of the maternal-fetal/neonatal inflammatory context in parasite-transmitting pregnant women and their congenitally infected newborns. Otherwise, experimental observations brought to light ADE of T. cruzi infection (involving FcγR) in mouse pups displaying maternally transferred antibodies, out of an inflammatory context. Herein, based on such data, we discuss the previously unconsidered possibility of a role of ADE in the trans-placental parasite transmission, and/or the development of severe and mortal clinical forms of congenital/neonatal Chagas disease in newborns of T. cruzi-infected mothers.

scholarly journals Absence of Bim sensitizes mice to experimental Trypanosoma cruzi infection

2021 ◽  
Vol 12 (7) ◽  
Author(s):  
Marcela Hernández-Torres ◽  
Rogério Silva do Nascimento ◽  
Monica Cardozo Rebouças ◽  
Alexandra Cassado ◽  
Kely Catarine Matteucci ◽  
...  
Keyword(s):  
T Cells ◽  
Trypanosoma Cruzi ◽  
Chagas Disease ◽  
Parasite Load ◽  
Peritoneal Macrophages ◽  
T Cell Response ◽  
No Production ◽  
Similar Reduction ◽  
Ifn Γ

AbstractChagas disease is a life-threatening disorder caused by the protozoan parasite Trypanosoma cruzi. Parasite-specific antibodies, CD8+ T cells, as well as IFN-γ and nitric oxide (NO) are key elements of the adaptive and innate immunity against the extracellular and intracellular forms of the parasite. Bim is a potent pro-apoptotic member of the Bcl-2 family implicated in different aspects of the immune regulation, such as negative selection of self-reactive thymocytes and elimination of antigen-specific T cells at the end of an immune response. Interestingly, the role of Bim during infections remains largely unidentified. To explore the role of Bim in Chagas disease, we infected WT, Bim+/−, Bim−/− mice with trypomastigotes forms of the Y strain of T. cruzi. Strikingly, our data revealed that Bim−/− mice exhibit a delay in the development of parasitemia followed by a deficiency in the control of parasite load in the bloodstream and a decreased survival compared to WT and Bim+/− mice. At the peak of parasitemia, peritoneal macrophages of Bim−/− mice exhibit decreased NO production, which correlated with a decrease in the pro-inflammatory Small Peritoneal Macrophage (SPM) subset. A similar reduction in NO secretion, as well as in the pro-inflammatory cytokines IFN-γ and IL-6, was also observed in Bim−/− splenocytes. Moreover, an impaired anti-T. cruzi CD8+ T-cell response was found in Bim−/− mice at this time point. Taken together, our results suggest that these alterations may contribute to the establishment of a delayed yet enlarged parasitic load observed at day 9 after infection of Bim−/− mice and place Bim as an important protein in the control of T. cruzi infections.

scholarly journals Neurotrophin Receptor TrkC Is an Entry Receptor for Trypanosoma cruzi in Neural, Glial, and Epithelial Cells

2011 ◽  
Vol 79 (10) ◽  
pp. 4081-4087 ◽  
Author(s):  
Craig Weinkauf ◽  
Ryan Salvador ◽  
Mercio PereiraPerrin
Keyword(s):  
Trypanosoma Cruzi ◽  
Chagas Disease ◽  
Mammalian Cells ◽  
Chinese Hamster ◽  
Neuronal Cell ◽  
Host Cells ◽  
Neurotrophin Receptor ◽  
Content Type

ABSTRACTTrypanosoma cruzi, the agent of Chagas' disease, infects a variety of mammalian cells in a process that includes multiple cycles of intracellular division and differentiation starting with host receptor recognition by a parasite ligand(s). Earlier work in our laboratory showed that the neurotrophin-3 (NT-3) receptor TrkC is activated byT. cruzisurfacetrans-sialidase, also known as parasite-derived neurotrophic factor (PDNF). However, it has remained unclear whether TrkC is used byT. cruzito enter host cells. Here, we show that a neuronal cell line (PC12-NNR5) relatively resistant toT. cruzibecame highly susceptible to infection when overexpressing human TrkC but not human TrkB. Furthermore,trkCtransfection conferred an ∼3.0-fold intracellular growth advantage. Sialylation-deficient Chinese hamster ovarian (CHO) epithelial cell lines Lec1 and Lec2 also became much more permissive toT. cruziafter transfection with thetrkCgene. Additionally, NT-3 specifically blockedT. cruziinfection of the TrkC-NNR5 transfectants and of naturally permissive TrkC-bearing Schwann cells and astrocytes, as did recombinant PDNF. Two specific inhibitors of Trk autophosphorylation (K252a and AG879) and inhibitors of Trk-induced MAPK/Erk (U0126) and Akt kinase (LY294002) signaling, but not an inhibitor of insulin-like growth factor 1 receptor, abrogated TrkC-mediated cell invasion. Antibody to TrkC blockedT. cruziinfection of the TrkC-NNR5 transfectants and of cells that naturally express TrkC. The TrkC antibody also significantly and specifically reduced cutaneous infection in a mouse model of acute Chagas' disease. TrkC is ubiquitously expressed in the peripheral and central nervous systems, and in nonneural cells infected byT. cruzi, including cardiac and gastrointestinal muscle cells. Thus, TrkC is implicated as a functional PDNF receptor in cell entry, independently of sialic acid recognition, mediating broadT. cruziinfection bothin vitroandin vivo.

scholarly journals In Vitro and In Vivo Activities of E5700 and ER-119884, Two Novel Orally Active Squalene Synthase Inhibitors, against Trypanosoma cruzi

2004 ◽  
Vol 48 (7) ◽  
pp. 2379-2387 ◽  
Author(s):  
Julio A. Urbina ◽  
Juan Luis Concepcion ◽  
Aura Caldera ◽  
Gilberto Payares ◽  
Cristina Sanoja ◽  
...  
Keyword(s):  
Trypanosoma Cruzi ◽  
Chagas Disease ◽  
Public Health Problem ◽  
Squalene Synthase ◽  
Host Cells ◽  
In Vivo Studies ◽  
Inorganic Pyrophosphate ◽  
Orally Active

ABSTRACT Chagas' disease is a serious public health problem in Latin America, and no treatment is available for the prevalent chronic stage. Its causative agent, Trypanosoma cruzi, requires specific endogenous sterols for survival, and we have recently demonstrated that squalene synthase (SQS) is a promising target for antiparasitic chemotherapy. E5700 and ER-119884 are quinuclidine-based inhibitors of mammalian SQS that are currently in development as cholesterol- and triglyceride-lowering agents in humans. These compounds were found to be potent noncompetitive or mixed-type inhibitors of T. cruzi SQS with K i values in the low nanomolar to subnanomolar range in the absence or presence of 20 μM inorganic pyrophosphate. The antiproliferative 50% inhibitory concentrations of the compounds against extracellular epimastigotes and intracellular amastigotes were ca. 10 nM and 0.4 to 1.6 nM, respectively, with no effects on host cells. When treated with these compounds at the MIC, all of the parasite's sterols disappeared from the parasite cells. In vivo studies indicated that E5700 was able to provide full protection against death and completely arrested the development of parasitemia when given at a concentration of 50 mg/kg of body weight/day for 30 days, while ER-119884 provided only partial protection. This is the first report of an orally active SQS inhibitor that is capable of providing complete protection against fulminant, acute Chagas' disease.

scholarly journals Characterization of Trypanosoma cruzi Sirtuins as Possible Drug Targets for Chagas Disease

2015 ◽  
Vol 59 (8) ◽  
pp. 4669-4679 ◽  
Author(s):  
Nilmar Silvio Moretti ◽  
Leonardo da Silva Augusto ◽  
Tatiana Mordente Clemente ◽  
Raysa Paes Pinto Antunes ◽  
Nobuko Yoshida ◽  
...  
Keyword(s):  
Trypanosoma Cruzi ◽  
Chagas Disease ◽  
Drug Targets ◽  
Wild Type ◽  
Content Type ◽  
Damage Repair ◽  
Lysine Deacetylases

ABSTRACTAcetylation of lysine is a major posttranslational modification of proteins and is catalyzed by lysine acetyltransferases, while lysine deacetylases remove acetyl groups. Among the deacetylases, the sirtuins are NAD+-dependent enzymes, which modulate gene silencing, DNA damage repair, and several metabolic processes. As sirtuin-specific inhibitors have been proposed as drugs for inhibiting the proliferation of tumor cells, in this study, we investigated the role of these inhibitors in the growth and differentiation ofTrypanosoma cruzi, the agent of Chagas disease. We found that the use of salermide during parasite infection prevented growth and initial multiplication after mammalian cell invasion byT. cruziat concentrations that did not affect host cell viability. In addition,in vivoinfection was partially controlled upon administration of salermide. There are two sirtuins inT. cruzi, TcSir2rp1 and TcSir2rp3. By using specific antibodies and cell lines overexpressing the tagged versions of these enzymes, we found that TcSir2rp1 is localized in the cytosol and TcSir2rp3 in the mitochondrion. TcSir2rp1 overexpression acts to impair parasite growth and differentiation, whereas the wild-type version of TcSir2rp3 and not an enzyme mutated in the active site improves both. The effects observed with TcSir2rp3 were fully reverted by adding salermide, which inhibited TcSir2rp3 expressed inEscherichia coliwith a 50% inhibitory concentration (IC50) ± standard error of 1 ± 0.5 μM. We concluded that sirtuin inhibitors targeting TcSir2rp3 could be used in Chagas disease chemotherapy.

scholarly journals Lysosomal Fusion Is Essential for the Retention of Trypanosoma cruzi Inside Host Cells

2004 ◽  
Vol 200 (9) ◽  
pp. 1135-1143 ◽  
Author(s):  
Luciana O. Andrade ◽  
Norma W. Andrews
Keyword(s):  
Plasma Membrane ◽  
Life Cycle ◽  
Trypanosoma Cruzi ◽  
Parasitophorous Vacuole ◽  
Cell Types ◽  
Significant Fraction ◽  
Host Cells ◽  
Productive Infection ◽  
Kinase Inhibition

Trypomastigotes, the highly motile infective forms of Trypanosoma cruzi, are capable of infecting several cell types. Invasion occurs either by direct recruitment and fusion of lysosomes at the plasma membrane, or through invagination of the plasma membrane followed by intracellular fusion with lysosomes. The lysosome-like parasitophorous vacuole is subsequently disrupted, releasing the parasites for replication in the cytosol. The role of this early residence within lysosomes in the intracellular cycle of T. cruzi has remained unclear. For several other cytosolic pathogens, survival inside host cells depends on an early escape from phagosomes before lysosomal fusion. Here, we show that when lysosome-mediated T. cruzi invasion is blocked through phosophoinositide 3-kinase inhibition, a significant fraction of the internalized parasites are not subsequently retained inside host cells for a productive infection. A direct correlation was observed between the lysosomal fusion rates after invasion and the intracellular retention of trypomastigotes. Thus, formation of a parasitophorous vacuole with lysosomal properties is essential for preventing these highly motile parasites from exiting host cells and for allowing completion of the intracellular life cycle.

scholarly journals Efficacy of Novel Pyrazolone Phosphodiesterase Inhibitors in Experimental Mouse Models of Trypanosoma cruzi

2020 ◽  
Vol 64 (9) ◽  
Author(s):  
Julianna Siciliano de Araújo ◽  
Cristiane França da Silva ◽  
Denise da Gama Jaén Batista ◽  
Aline Nefertiti ◽  
Ludmila Ferreira de Almeida Fiuza ◽  
...  
Keyword(s):  
Trypanosoma Cruzi ◽  
Chagas Disease ◽  
Phosphodiesterase Inhibitors ◽  
Biological Properties ◽  
Host Cells ◽  
Mammalian Host ◽  
Intracellular Camp ◽  
Additive Interaction ◽  
Content Type

ABSTRACT Pyrazolones are heterocyclic compounds with interesting biological properties. Some derivatives inhibit phosphodiesterases (PDEs) and thereby increase the cellular concentration of cyclic AMP (cAMP), which plays a vital role in the control of metabolism in eukaryotic cells, including the protozoan Trypanosoma cruzi, the etiological agent of Chagas disease (CD), a major neglected tropical disease. In vitro phenotypic screening identified a 4-bromophenyl-dihydropyrazole dimer as an anti-T. cruzi hit and 17 novel pyrazolone analogues with variations on the phenyl ring were investigated in a panel of phenotypic laboratory models. Potent activity against the intracellular forms (Tulahuen and Y strains) was obtained with 50% effective concentration (EC50) values within the 0.17 to 3.3 μM range. Although most were not active against bloodstream trypomastigotes, an altered morphology and loss of infectivity were observed. Pretreatment of the mammalian host cells with pyrazolones did not interfere with infection and proliferation, showing that the drug activity was not the result of changes to host cell metabolism. The pyrazolone NPD-227 increased the intracellular cAMP levels and was able to sterilize T. cruzi-infected cell cultures. Thus, due to its high potency and selectivity in vitro, and its additive interaction with benznidazole (Bz), NPD-227 was next assessed in the acute mouse model. Oral dosing for 5 days of NPD-227 at 10 mg/kg + Bz at 10 mg/kg not only reduced parasitemia (>87%) but also protected against mortality (>83% survival), hence demonstrating superiority to the monotherapy schemes. These data support these pyrazolone molecules as potential novel therapeutic alternatives for Chagas disease.

scholarly journals Amaryllidaceae alkaloids with anti-Trypanosoma cruzi activity

2020 ◽  
Author(s):  
Nieves Martinez-Peinado ◽  
Nuria Cortes-Serra ◽  
Laura Torras-Claveria ◽  
Maria-Jesus Pinazo ◽  
Joaquim Gascon ◽  
...  
Keyword(s):  
Natural Products ◽  
Trypanosoma Cruzi ◽  
Chagas Disease ◽  
New Drugs ◽  
Host Cells ◽  
Amaryllidaceae Alkaloids ◽  
Cytotoxicity Assays ◽  
Limited Efficacy ◽  
Single Compound ◽  
New Compounds

Abstract Background: Chagas disease, caused by the protozoan Trypanosoma cruzi, is a neglected disease that affects ~7 million people worldwide. Development of new drugs to treat the infection remains a priority since those currently available have frequent side effects and limited efficacy at the chronic stage. Natural products provide a pool of diversity structures to lead the chemical synthesis of novel molecules for this purpose. Herein we analyzed the anti- T. cruzi activity of 9 alkaloids derived from plants of the Amaryllidaceae family. Methods: the activity of each alkaloid was assessed by means of a newly developed anti- T. cruzi phenotypic assay. We further evaluated the compounds that inhibited the parasite growth on two distinct cytotoxicity assays to discard those that were toxic to host cells and assure parasite selectivity. Results: we identified a single compound (hippeastrine 2 ) that was selectively active against the parasite yielding selectivity indexes of 12.7 and 35.2 against Vero and HepG2 cells, respectively. Conclusions: results reported here suggest that natural products are an interesting source of new compounds for the development of drugs against Chagas disease.

scholarly journals Glycans in Virus-Host Interactions: A Structural Perspective

2021 ◽  
Vol 8 ◽  
Author(s):  
Nathaniel L. Miller ◽  
Thomas Clark ◽  
Rahul Raman ◽  
Ram Sasisekharan
Keyword(s):  
Immune System ◽  
Host Cells ◽  
Host Immune System ◽  
Host Interactions ◽  
Viral Glycoproteins ◽  
Microbe Interactions ◽  
Host Microbe Interactions ◽  
Anti Hiv ◽  
Structural Perspective

Many interactions between microbes and their hosts are driven or influenced by glycans, whose heterogeneous and difficult to characterize structures have led to an underappreciation of their role in these interactions compared to protein-based interactions. Glycans decorate microbe glycoproteins to enhance attachment and fusion to host cells, provide stability, and evade the host immune system. Yet, the host immune system may also target these glycans as glycoepitopes. In this review, we provide a structural perspective on the role of glycans in host-microbe interactions, focusing primarily on viral glycoproteins and their interactions with host adaptive immunity. In particular, we discuss a class of topological glycoepitopes and their interactions with topological mAbs, using the anti-HIV mAb 2G12 as the archetypical example. We further offer our view that structure-based glycan targeting strategies are ready for application to viruses beyond HIV, and present our perspective on future development in this area.

scholarly journals Bioluminescent:fluorescent Trypanosoma cruzi Reporter Strains as Tools for Exploring Chagas Disease Pathogenesis and Drug Activity

2020 ◽  
Vol 26 ◽  
Author(s):  
Martin C. Taylor ◽  
Alexander I. Ward ◽  
Francisco Olmo ◽  
Amanda F. Francisco ◽  
Shiromani Jayawardhana ◽  
...  
Keyword(s):  
Trypanosoma Cruzi ◽  
Chagas Disease ◽  
Parasite Burden ◽  
New Drugs ◽  
Host Cells ◽  
Complex Nature ◽  
Disease Pathogenesis ◽  
Drug Activity ◽  
Cellular Environment

: Chagas disease results from infection with the trypanosomatid parasite Trypanosoma cruzi. Progress in developing new drugs has been hampered by the long term and complex nature of the condition and by our limited understanding of parasite biology. Technical difficulties in assessing the parasite burden during the chronic stage of infection have also proved to be a particular challenge. In this context, the development of non-invasive, highly sensitive bioluminescence imaging procedures, based on parasites that express a red-shifted luciferase, has greatly enhanced our ability to monitor infections in experimental models. Applications of this methodology have led to new insights into tissue tropism and infection dynamics, and have been a major driver in drug development. The system has been further modified by the generation of parasite reporter lines that express bioluminescent:fluorescent fusion proteins, an advance that has allowed chronic infections in mice to be examined at a cellular level. By exploiting bioluminescence to identify the rare sites of tissue infection, and fluorescence to detect T. cruzi at the level of individual host cells in histological sections, it has been possible to investigate the replication and differentiation status of parasites in vivo and to examine the cellular environment of infection foci. In combination, these data are providing a framework for the detailed dissection of disease pathogenesis and drug activity.

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