scholarly journals Parasite-Derived Neurotrophic Factor/trans-Sialidase of Trypanosoma cruzi Links Neurotrophic Signaling to Cardiac Innate Immune Response

2014 ◽  
Vol 82 (9) ◽  
pp. 3687-3696 ◽  
Author(s):  
Ryan Salvador ◽  
Daniel Aridgides ◽  
Mercio PereiraPerrin
Keyword(s):  
Innate Immunity ◽  
Trypanosoma Cruzi ◽  
Neurotrophic Factor ◽  
Neutralizing Antibodies ◽  
Tissue Growth ◽  
Content Type ◽  
Monocyte Chemoattractant Protein 1 ◽  
Neurotrophic Signaling ◽  
Neurotrophic Receptors ◽  
Dose Dependent Increase

ABSTRACTThe Chagas' disease parasiteTrypanosoma cruzielicits a potent inflammatory response in acutely infected hearts that keeps parasitism in check and triggers cardiac abnormalities. A most-studied mechanism underlying innate immunity inT. cruziinfection is Toll-like receptor (TLR) activation by lipids and other parasite molecules. However, yet-to-be-identified pathways should exist. Here, we show thatT. cruzistrongly upregulates monocyte chemoattractant protein 1 (MCP-1)/CCL2 and fractalkine (FKN)/CX3CL1 in cellular and mouse models of heart infection. Mechanistically, upregulation of MCP-1 and FKN stems from the interaction of parasite-derived neurotrophic factor (PDNF)/trans-sialidase with neurotrophic receptors TrkA and TrkC, as assessed by pharmacological inhibition, neutralizing antibodies, and gene silencing studies. Administration of a single dose of intravenous PDNF to naive mice results in a dose-dependent increase in MCP-1 and FKN in the heart and liver with pulse-like kinetics that peak at 3 h postinjection. Intravenous PDNF also augments MCP-1 and FKN in TLR signaling-deficient MyD88-knockout mice, underscoring the MyD88-independent action of PDNF. Although single PDNF injections do not increase MCP-1 and FKN receptors, multiple PDNF injections at short intervals up the levels of receptor transcripts in the heart and liver, suggesting that sustained PDNF triggers cell recruitment at infection sites. Thus, given that MCP-1 and FKN are chemokines essential to the recruitment of immune cells to combat inflammation triggers and to enhance tissue repair, our findings uncover a new mechanism in innate immunity againstT. cruziinfection mediated by Trk signaling akin to an endogenous inflammatory and fibrotic pathway resulting from cardiomyocyte-TrkA recognition by matricellular connective tissue growth factor (CTGF/CCN2).

scholarly journals Toll-Like Receptor 4 Agonistic Antibody Promotes Innate Immunity against Severe Pneumonia Induced by Coinfection with Influenza Virus and Streptococcus pneumoniae

2013 ◽  
Vol 20 (7) ◽  
pp. 977-985 ◽  
Author(s):  
Akitaka Tanaka ◽  
Shigeki Nakamura ◽  
Masafumi Seki ◽  
Kenji Fukudome ◽  
Naoki Iwanaga ◽  
...  
Keyword(s):  
Innate Immunity ◽  
Influenza Virus ◽  
Streptococcus Pneumoniae ◽  
Pneumococcal Pneumonia ◽  
Survival Rates ◽  
Severe Pneumonia ◽  
Histopathological Study ◽  
Toll Like Receptor ◽  
Content Type ◽  
Monocyte Chemoattractant Protein 1

ABSTRACTCoinfection with bacteria is a major cause of mortality during influenza epidemics. Recently, Toll-like receptor (TLR) agonists were shown to have immunomodulatory functions. In the present study, we investigated the effectiveness and mechanisms of the new TLR4 agonistic monoclonal antibody UT12 against secondary pneumococcal pneumonia induced by coinfection with influenza virus in a mouse model. Mice were intranasally inoculated withStreptococcus pneumoniae2 days after influenza virus inoculation. UT12 was intraperitoneally administered 2 h before each inoculation. Survival rates were significantly increased and body weight loss was significantly decreased by UT12 administration. Additionally, the production of inflammatory mediators was significantly suppressed by the administration of UT12. In a histopathological study, pneumonia in UT12-treated mice was very mild compared to that in control mice. UT12 increased antimicrobial defense through the acceleration of macrophage recruitment into the lower respiratory tract induced by c-Jun N-terminal kinase (JNK) and nuclear factor kappaB (NF-κB) pathway-dependent monocyte chemoattractant protein 1 (MCP-1) production. Collectively, these findings indicate that UT12 promoted pulmonary innate immunity and may reduce the severity of severe pneumonia induced by coinfection with influenza virus andS. pneumoniae. This immunomodulatory effect of UT12 improves the prognosis of secondary pneumococcal pneumonia and makes UT12 an attractive candidate for treating severe infectious diseases.

scholarly journals New Scheme of Intermittent Benznidazole Administration in Patients Chronically Infected with Trypanosoma cruzi: Clinical, Parasitological, and Serological Assessment after Three Years of Follow-Up

2020 ◽  
Vol 64 (9) ◽  
Author(s):  
María Gabriela Álvarez ◽  
Juan Carlos Ramírez ◽  
Graciela Bertocchi ◽  
Marisa Fernández ◽  
Yolanda Hernández ◽  
...  
Keyword(s):  
Trypanosoma Cruzi ◽  
Nuclear Dna ◽  
Parasite Load ◽  
Serological Tests ◽  
Content Type ◽  
Monocyte Chemoattractant Protein 1 ◽  
Specific Antibodies ◽  
Intermittent Administration ◽  
Low Rate

ABSTRACT In a pilot study, we showed that the intermittent administration of benznidazole in chronic Chagas disease patients resulted in a low rate of treatment suspension and therapeutic failure, as assessed by quantitative PCR (qPCR) at the end of treatment. Here, a 3-year posttreatment follow-up study of the same cohort of patients is presented. The treatment scheme consisted of 12 doses of benznidazole at 5 mg/kg of body weight/day in two daily doses every 5 days. Parasite load, Trypanosoma cruzi-specific antibodies, and serum chemokine levels were measured prior to treatment and after a median follow-up of 36 months posttreatment by DNA minicircle kinetoplastid and nuclear DNA satellite sequence qPCR methods, conventional serological techniques, a Luminex-based assay with recombinant T. cruzi proteins, and a cytometric bead array. At the end of follow-up, 14 of 17 (82%) patients had negative qPCR findings, whereas three of 17 (18%) had detectable nonquantifiable findings by at least one of the qPCR techniques. A decline in parasite-specific antibodies at 12 months posttreatment was confirmed by conventional serological tests and the Luminex assays. Monocyte chemoattractant protein 1 levels increased after treatment, whereas monokine induced by gamma interferon levels decreased. New posttreatment electrocardiographic abnormalities were observed in only one patient who had cardiomyopathy prior to treatment. Together, these data strengthen our previous findings by showing that the intermittent administration of benznidazole results in a low rate of treatment suspension, with treatment efficacy comparable to that of a daily dose of 5 mg/kg for 60 days.

scholarly journals trans-Sialidase Neutralizing Antibody Detection in Trypanosoma cruzi-Infected Domestic Reservoirs

2011 ◽  
Vol 18 (6) ◽  
pp. 984-989 ◽  
Author(s):  
Paula A. Sartor ◽  
Martha V. Cardinal ◽  
Marcela M. Orozco ◽  
Ricardo E. Gürtler ◽  
M. Susana Leguizamón
Keyword(s):  
Visceral Leishmaniasis ◽  
Trypanosoma Cruzi ◽  
Neutralizing Antibodies ◽  
Cross Reactivity ◽  
Antibody Detection ◽  
Enzyme Linked Immunosorbent Assay ◽  
Trypanosoma Rangeli ◽  
Serum Samples ◽  
Dipstick Test ◽  
Content Type

ABSTRACTThe detection ofTrypanosoma cruziinfection in domestic dogs and cats is relevant to evaluating human transmission risks and the effectiveness of insecticide spraying campaigns. However, the serological assays routinely used are associated with cross-reactivity in sera from mammals infected withLeishmaniaspp. We used atrans-sialidase inhibition assay (TIA) forT. cruzidiagnosis in serum samples from 199 dogs and 57 cats from areas where these types of infections are endemic. TIA is based on the antibody neutralization of recombinanttrans-sialidase, an enzyme that is not detected in the coendemicLeishmaniaspecies orTrypanosoma rangeliparasites.T. cruziinfection was also evaluated by conventional serology (CS) (indirect immunofluorescence, indirect hemagglutination, enzyme-linked immunosorbent assay, and immunochromatographic dipstick test) and xenodiagnosis. Sera from 30 dogs and 15 cats from areas where these organisms are not endemic and 5 dogs with visceral leishmaniasis were found to be nonreactive by TIA and CS. Samples from dogs and cats demonstrated 91 and 95% copositivities between TIA and CS, whereas the conegativities were 98 and 97%, respectively. Sera from xenodiagnosis-positive dogs and cats also reacted by TIA (copositivities of 97 and 83%, respectively). TIA was reactive in three CS-negative samples and was able to resolve results in two cat serum samples that were CS inconclusive. Our study is the first to describe the development oftrans-sialidase neutralizing antibodies in naturally infected dogs and cats. High CS conegativity and the absence oftrans-sialidase neutralization in dog sera from areas where leishmaniasis is not endemic and from dogs with visceral leishmaniasis support TIA specificity. The TIA may be a useful tool forT. cruzidetection in the main domestic reservoirs.

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 Long-Term Immunity to Trypanosoma cruzi in the Absence of Immunodominanttrans-Sialidase-Specific CD8+T Cells

2016 ◽  
Vol 84 (9) ◽  
pp. 2627-2638 ◽  
Author(s):  
Charles S. Rosenberg ◽  
Weibo Zhang ◽  
Juan M. Bustamante ◽  
Rick L. Tarleton
Keyword(s):  
T Cells ◽  
T Cell ◽  
Transgenic Mice ◽  
Trypanosoma Cruzi ◽  
T Cell Responses ◽  
Content Type ◽  
Cell Responses ◽  
Pathogen Control ◽  
Immunodominant Epitopes

Trypanosoma cruziinfection drives the expansion of remarkably focused CD8+T cell responses targeting epitopes encoded by varianttrans-sialidase (TS) genes. Infection of C57BL/6 mice withT. cruziresults in up to 40% of all CD8+T cells committed to recognition of the dominant TSKB20 and subdominant TSKB18 TS epitopes. However, despite this enormous response, these mice fail to clearT. cruziinfection and subsequently develop chronic disease. One possible reason for the failure to cureT. cruziinfection is that immunodomination by these TS-specific T cells may interfere with alternative CD8+T cell responses more capable of complete parasite elimination. To address this possibility, we created transgenic mice that are centrally tolerant to these immunodominant epitopes. Mice expressing TSKB20, TSKB18, or both epitopes controlledT. cruziinfection and developed effector CD8+T cells that maintained an activated phenotype. Memory CD8+T cells from drug-cured TSKB-transgenic mice rapidly responded to secondaryT. cruziinfection. In the absence of the response to TSKB20 and TSKB18, immunodominance did not shift to other known subdominant epitopes despite the capacity of these mice to expand epitope-specific T cells specific for the model antigen ovalbumin expressed by engineered parasites. Thus, CD8+T cell responses tightly and robustly focused on a few epitopes within variant TS antigens appear to neither contribute to, nor detract from, the ability to controlT. cruziinfection. These data also indicate that the relative position of an epitope within a CD8+immunodominance hierarchy does not predict its importance in pathogen control.

scholarly journals Nitro/Nitrosyl-Ruthenium Complexes Are Potent and Selective Anti-Trypanosoma cruzi Agents Causing Autophagy and Necrotic Parasite Death

2014 ◽  
Vol 58 (10) ◽  
pp. 6044-6055 ◽  
Author(s):  
Tanira M. Bastos ◽  
Marília I. F. Barbosa ◽  
Monize M. da Silva ◽  
José W. da C. Júnior ◽  
Cássio S. Meira ◽  
...  
Keyword(s):  
Trypanosoma Cruzi ◽  
Inhibitory Concentration ◽  
Content Type ◽  
X Ray ◽  
X Ray Crystallography ◽  
Ruthenium Nitrosyl ◽  
Index Analysis ◽  
Antiparasitic Drug ◽  
Drug Complex

ABSTRACTcis-[RuCl(NO2)(dppb)(5,5′-mebipy)] (complex 1),cis-[Ru(NO2)2(dppb)(5,5′-mebipy)] (complex 2),ct-[RuCl(NO)(dppb)(5,5′-mebipy)](PF6)2(complex 3), andcc-[RuCl(NO)(dppb)(5,5′-mebipy)](PF6)2(complex 4), where 5,5′-mebipy is 5,5′-dimethyl-2,2′-bipyridine and dppb is 1,4-bis(diphenylphosphino)butane, were synthesized and characterized. The structure of complex 2 was determined by X-ray crystallography. These complexes exhibited a higher anti-Trypanosoma cruziactivity than benznidazole, the current antiparasitic drug. Complex 3 was the most potent, displaying a 50% effective concentration (EC50) of 2.1 ± 0.6 μM against trypomastigotes and a 50% inhibitory concentration (IC50) of 1.3 ± 0.2 μM against amastigotes, while it displayed a 50% cytotoxic concentration (CC50) of 51.4 ± 0.2 μM in macrophages. It was observed that the nitrosyl complex 3, but not its analog lacking the nitrosyl group, releases nitric oxide into parasite cells. This release has a diminished effect on the trypanosomal protease cruzain but induces substantial parasite autophagy, which is followed by a series of irreversible morphological impairments to the parasites and finally results in cell death by necrosis. In infected mice, orally administered complex 3 (five times at a dose of 75 μmol/kg of body weight) reduced blood parasitemia and increased the survival rate of the mice. Combination index analysis of complex 3 indicated that itsin vitroactivity against trypomastigotes is synergic with benznidazole. In addition, drug combination enhanced efficacy in infected mice, suggesting that ruthenium-nitrosyl complexes are potential constituents for drug combinations.

scholarly journals Invasion of Oral and Aortic Tissues by Oral Spirochete Treponema denticola in ApoE−/−Mice Causally Links Periodontal Disease and Atherosclerosis

2014 ◽  
Vol 82 (5) ◽  
pp. 1959-1967 ◽  
Author(s):  
Sasanka S. Chukkapalli ◽  
Mercedes F. Rivera ◽  
Irina M. Velsko ◽  
Ju-Youn Lee ◽  
Hao Chen ◽  
...  
Keyword(s):  
Periodontal Disease ◽  
Alveolar Bone ◽  
Tissue Growth ◽  
Aortic Tissue ◽  
Treponema Denticola ◽  
Rapid Progression ◽  
Causative Role ◽  
Igg Antibody ◽  
Content Type ◽  
Periodontal Infection

ABSTRACTTreponema denticolais a predominantly subgingival oral spirochete closely associated with periodontal disease and has been detected in atherosclerosis. This study was designed to evaluate causative links between periodontal disease induced by chronic oralT. denticolainfection and atherosclerosis in hyperlipidemic ApoE−/−mice. ApoE−/−mice (n= 24) were orally infected withT. denticolaATCC 35404 and were euthanized after 12 and 24 weeks.T. denticolagenomic DNA was detected in oral plaque samples, indicating colonization of the oral cavity. Infection elicited significantly (P= 0.0172) higher IgG antibody levels and enhanced intrabony defects than sham infection.T. denticola-infected mice had higher levels of horizontal alveolar bone resorption than sham-infected mice and an associated significant increase in aortic plaque area (P≤ 0.05). Increased atherosclerotic plaque correlated with reduced serum nitric oxide (NO) levels and increased serum-oxidized low-density lipoprotein (LDL) levels compared to those of sham-infected mice.T. denticolainfection altered the expression of genes known to be involved in atherosclerotic development, including the leukocyte/endothelial cell adhesion gene (Thbs4), the connective tissue growth factor gene (Ctgf), and the selectin-E gene (Sele). Fluorescentin situhybridization (FISH) revealedT. denticolaclusters in both gingival and aortic tissue of infected mice. This is the first study examining the potential causative role of chronicT. denticolaperiodontal infection and vascular atherosclerosisin vivoin hyperlipidemic ApoE−/−mice.T. denticolais closely associated with periodontal disease and the rapid progression of atheroma in ApoE−/−mice. These studies confirm a causal link for active oralT. denticolainfection with both atheroma and periodontal disease.

scholarly journals Bacterially Expressed Full-Length Recombinant Plasmodium falciparum RH5 Protein Binds Erythrocytes and Elicits Potent Strain-Transcending Parasite-Neutralizing Antibodies

2013 ◽  
Vol 82 (1) ◽  
pp. 152-164 ◽  
Author(s):  
K. Sony Reddy ◽  
Alok K. Pandey ◽  
Hina Singh ◽  
Tajali Sahar ◽  
Amlabu Emmanuel ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Neutralizing Antibodies ◽  
Malaria Vaccine ◽  
Expression System ◽  
Full Length ◽  
Blood Stage ◽  
Parasite Protein ◽  
Content Type ◽  
Erythrocyte Binding ◽  
Blood Stage Malaria

ABSTRACTPlasmodium falciparumreticulocyte binding-like homologous protein 5 (PfRH5) is an essential merozoite ligand that binds with its erythrocyte receptor, basigin. PfRH5 is an attractive malaria vaccine candidate, as it is expressed by a wide number ofP. falciparumstrains, cannot be genetically disrupted, and exhibits limited sequence polymorphisms. Viral vector-induced PfRH5 antibodies potently inhibited erythrocyte invasion. However, it has been a challenge to generate full-length recombinant PfRH5 in a bacterial-cell-based expression system. In this study, we have produced full-length recombinant PfRH5 inEscherichia colithat exhibits specific erythrocyte binding similar to that of the native PfRH5 parasite protein and also, importantly, elicits potent invasion-inhibitory antibodies against a number ofP. falciparumstrains. Antibasigin antibodies blocked the erythrocyte binding of both native and recombinant PfRH5, further confirming that they bind with basigin. We have thus successfully produced full-length PfRH5 as a functionally active erythrocyte binding recombinant protein with a conformational integrity that mimics that of the native parasite protein and elicits potent strain-transcending parasite-neutralizing antibodies.P. falciparumhas the capability to develop immune escape mechanisms, and thus, blood-stage malaria vaccines that target multiple antigens or pathways may prove to be highly efficacious. In this regard, antibody combinations targeting PfRH5 and other key merozoite antigens produced potent additive inhibition against multiple worldwideP. falciparumstrains. PfRH5 was immunogenic when immunized with other antigens, eliciting potent invasion-inhibitory antibody responses with no immune interference. Our results strongly support the development of PfRH5 as a component of a combination blood-stage malaria vaccine.

scholarly journals A Multiepitope Fusion Antigen Elicits Neutralizing Antibodies against Enterotoxigenic Escherichia coli and Homologous Bovine Viral Diarrhea VirusIn Vitro

2013 ◽  
Vol 20 (7) ◽  
pp. 1076-1083 ◽  
Author(s):  
Emad A. Hashish ◽  
Chengxian Zhang ◽  
Xiaosai Ruan ◽  
David E. Knudsen ◽  
Christopher C. Chase ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Viral Infection ◽  
Neutralizing Antibodies ◽  
Cell Epitope ◽  
Enterotoxigenic Escherichia Coli ◽  
Bovine Viral Diarrhea ◽  
Content Type ◽  
Diarrhea Virus ◽  
Viral Diarrhea ◽  
Fusion Antigen

ABSTRACTDiarrhea is one of the most important bovine diseases. EnterotoxigenicEscherichia coli(ETEC) and bovine viral diarrhea virus (BVDV) are the major causes of diarrhea in calves and cattle. ETEC expressing K99 (F5) fimbriae and heat-stable type Ia (STa) toxin are the leading bacteria causing calf diarrhea, and BVDV causes diarrhea and other clinical illnesses in cattle of all ages. It is reported that maternal immunization with K99 fimbrial antigens provides passive protection to calves against K99 fimbrial ETEC and that BVDV major structural protein E2 elicits antibodies neutralizing against BVDV viral infection. Vaccines inducing anti-K99 and anti-STa immunity would protect calves more effectively against ETEC diarrhea, and those also inducing anti-E2 neutralizing antibodies would protect calves and cattle against diarrhea caused by both ETEC and BVDV. In this study, we used the ETEC K99 major subunit FanC as a backbone, genetically embedded the STa toxoid STaP12Fand the most-antigenic B-cell epitope and T-cell epitope predicted from the BVDV E2 glycoprotein into FanC for the multivalent antigen FanC-STa-E2, and examined immunogenicity of this multivalent antigen to assess vaccine potential against bovine diarrhea. Mice intraperitoneally (i.p.) immunized with this multivalent antigen developed anti-K99, anti-STa, and anti-BVDV antibodies. Moreover, elicited antibodies showed neutralization activities, as they inhibited adherence of K99 fimbrialE. coli, neutralized STa toxin, and prevented homologous BVDV viral infectionin vitro. Results from this study suggest that this multiepitope fusion antigen can potentially be developed as a vaccine for broad protection against bovine diarrhea and that the multiepitope fusion strategy may be generally applied for multivalent vaccine development against heterogeneous pathogens.

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