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Silvestrini MMA, Alessio GD, Frias BED, Sales Júnior PA, Araújo MSS, Silvestrini CMA, Brito Alvim de Melo GE, Martins-Filho OA, Teixeira-Carvalho A, Martins HR. New insights into Trypanosoma cruzi genetic diversity, and its influence on parasite biology and clinical outcomes. Front Immunol 2024; 15:1342431. [PMID: 38655255 PMCID: PMC11035809 DOI: 10.3389/fimmu.2024.1342431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Accepted: 02/26/2024] [Indexed: 04/26/2024] Open
Abstract
Chagas disease, caused by Trypanosoma cruzi, remains a serious public health problem worldwide. The parasite was subdivided into six distinct genetic groups, called "discrete typing units" (DTUs), from TcI to TcVI. Several studies have indicated that the heterogeneity of T. cruzi species directly affects the diversity of clinical manifestations of Chagas disease, control, diagnosis performance, and susceptibility to treatment. Thus, this review aims to describe how T. cruzi genetic diversity influences the biology of the parasite and/or clinical parameters in humans. Regarding the geographic dispersion of T. cruzi, evident differences were observed in the distribution of DTUs in distinct areas. For example, TcII is the main DTU detected in Brazilian patients from the central and southeastern regions, where there are also registers of TcVI as a secondary T. cruzi DTU. An important aspect observed in previous studies is that the genetic variability of T. cruzi can impact parasite infectivity, reproduction, and differentiation in the vectors. It has been proposed that T. cruzi DTU influences the host immune response and affects disease progression. Genetic aspects of the parasite play an important role in determining which host tissues will be infected, thus heavily influencing Chagas disease's pathogenesis. Several teams have investigated the correlation between T. cruzi DTU and the reactivation of Chagas disease. In agreement with these data, it is reasonable to suppose that the immunological condition of the patient, whether or not associated with the reactivation of the T. cruzi infection and the parasite strain, may have an important role in the pathogenesis of Chagas disease. In this context, understanding the genetics of T. cruzi and its biological and clinical implications will provide new knowledge that may contribute to additional strategies in the diagnosis and clinical outcome follow-up of patients with Chagas disease, in addition to the reactivation of immunocompromised patients infected with T. cruzi.
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Affiliation(s)
| | - Glaucia Diniz Alessio
- Integrated Biomarker Research Group, René Rachou Institute, Fiocruz Minas, Oswaldo Cruz Foundation, Belo Horizonte, Minas Gerais, Brazil
| | - Bruna Estefânia Diniz Frias
- Integrated Biomarker Research Group, René Rachou Institute, Fiocruz Minas, Oswaldo Cruz Foundation, Belo Horizonte, Minas Gerais, Brazil
| | - Policarpo Ademar Sales Júnior
- Integrated Biomarker Research Group, René Rachou Institute, Fiocruz Minas, Oswaldo Cruz Foundation, Belo Horizonte, Minas Gerais, Brazil
| | - Márcio Sobreira Silva Araújo
- Integrated Biomarker Research Group, René Rachou Institute, Fiocruz Minas, Oswaldo Cruz Foundation, Belo Horizonte, Minas Gerais, Brazil
| | | | | | - Olindo Assis Martins-Filho
- Integrated Biomarker Research Group, René Rachou Institute, Fiocruz Minas, Oswaldo Cruz Foundation, Belo Horizonte, Minas Gerais, Brazil
| | - Andréa Teixeira-Carvalho
- Integrated Biomarker Research Group, René Rachou Institute, Fiocruz Minas, Oswaldo Cruz Foundation, Belo Horizonte, Minas Gerais, Brazil
| | - Helen Rodrigues Martins
- Department of Pharmacy, Federal University of the Jequitinhonha and Mucuri Valleys, Diamantina, Minas Gerais, Brazil
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Cutshaw MK, Sciaudone M, Bowman NM. Risk Factors for Progression to Chronic Chagas Cardiomyopathy: A Systematic Review and Meta-Analysis. Am J Trop Med Hyg 2023; 108:791-800. [PMID: 36848894 PMCID: PMC10076993 DOI: 10.4269/ajtmh.22-0630] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Accepted: 12/19/2022] [Indexed: 03/01/2023] Open
Abstract
Approximately one-third of people with chronic Trypanosoma cruzi infection develop Chagas cardiomyopathy, which carries a poor prognosis. Accurate prediction of which individuals will go on to develop Chagas cardiomyopathy remains elusive. We performed a systematic review of literature comparing characteristics of individuals with chronic Chagas disease with or without evidence of cardiomyopathy. Studies were not excluded on the basis of language or publication date. Our review yielded a total of 311 relevant publications. We further examined the subset of 170 studies with data regarding individual age, sex, or parasite load. A meta-analysis of 106 eligible studies indicated that male sex was associated with having Chagas cardiomyopathy (Hedge's g: 1.56, 95% CI: 1.07-2.04), and a meta-analysis of 91 eligible studies indicated that older age was associated with having Chagas cardiomyopathy (Hedge's g: 0.66, 95% CI: 0.41-0.91). A meta-analysis of four eligible studies did not find an association between parasite load and disease state. This study provides the first systematic review to assess whether age, sex, and parasite load are associated with Chagas cardiomyopathy. Our findings suggest that older and male patients with Chagas disease are more likely to have cardiomyopathy, although we are unable to identify causal relationships due to the high heterogeneity and predominantly retrospective study designs in the current literature. Prospective, multidecade studies are needed to better characterize the clinical course of Chagas disease and identify risk factors for progression to Chagas cardiomyopathy.
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Affiliation(s)
| | - Michael Sciaudone
- Section of Infectious Diseases, Tulane University School of Medicine, New Orleans, Louisiana
| | - Natalie M. Bowman
- Division of Infectious Diseases, Department of Medicine, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina
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3
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Oliveira Cavalcanti E, Freitas Lidani KC, de Freitas Oliveira Toré C, de Messias Reason IJ, Andrade FA. MASP1 Gene Polymorphism and MASP-3 Serum Levels in Patients with Chronic Chagas Disease. Immunol Invest 2022; 51:2108-2121. [PMID: 36166216 DOI: 10.1080/08820139.2022.2110503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
INTRODUCTION Chagas disease (CD), caused by Trypanosoma cruzi, is a major public health issue worldwide affecting 6-7 million people, mainly in Latin America. The complement system plays a crucial role in host immune defense against T. cruzi infection and during the chronic phase of CD; however, the role of the MBL-associated serine protease 1 (MASP1) gene encoding MASP-1, MASP-3, and MAp44 complement proteins has not yet been reported in CD. This study investigated the possible association between MASP1 gene polymorphisms and MASP-3 protein serum levels in chronic CD and its clinical forms. METHODS Five polymorphisms of MASP1 gene regulatory regions were genotyped in 214 patients with CD and 197 healthy controls (rs7609662 G>A, rs13064994 C>T, rs72549262 C>G, rs1109452 C>T and rs850314 G>A). MASP-3 serum levels were assessed in 70 patients and 66 healthy controls. Clinical data, serum levels of complement proteins (ficolin-2, ficolin-3 and MBL) and inflammatory markers (pentraxin-3 and hsCRP) were also included in the analyses. RESULTS A significant association of the MASP1 GC_CCA haplotype with CD (padj= 0.002; OR 3.17 [1.19-8.39]) and chronic chagasic cardiomyopathy (CCC) (padj= 0.013; OR 4.57 [1.37-15.16] was observed. MASP-3 and pentraxin-3 levels were positively correlated in the patients (rho = 0.62; p = 0.0001). MASP-3 levels were not associated with MASP1 polymorphisms or CD and its clinical forms. Furthermore, no correlation was observed between MASP-3 levels and that of ficolin-2, ficolin-3, MBL and hsCRP. CONCLUSION Our findings suggest a possible role for the MASP1 GC_CCA haplotype in susceptibility to chronic CD and CCC clinical forms.
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Affiliation(s)
- Ednéia Oliveira Cavalcanti
- Laboratory of Molecular Immunopathology, Clinical Hospital, Federal University of Paraná, Curitiba, Brazil
| | - Kárita Cláudia Freitas Lidani
- Laboratory of Molecular Immunopathology, Clinical Hospital, Federal University of Paraná, Curitiba, Brazil.,Division of Cardiovascular Medicine, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | | | | | - Fabiana Antunes Andrade
- Laboratory of Molecular Immunopathology, Clinical Hospital, Federal University of Paraná, Curitiba, Brazil.,Department of Medicine, Positivo University, Curitiba, Brazil
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4
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Caputo MB, Elias J, Cesar G, Alvarez MG, Laucella SA, Albareda MC. Role of the Complement System in the Modulation of T-Cell Responses in Chronic Chagas Disease. Front Cell Infect Microbiol 2022; 12:910854. [PMID: 35846776 PMCID: PMC9282465 DOI: 10.3389/fcimb.2022.910854] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 05/26/2022] [Indexed: 01/19/2023] Open
Abstract
Chagas disease, caused by the intracellular pathogen Trypanosoma cruzi, is the parasitic disease with the greatest impact in Latin America and the most common cause of infectious myocarditis in the world. The immune system plays a central role in the control of T. cruzi infection but at the same time needs to be controlled to prevent the development of pathology in the host. It has been shown that persistent infection with T. cruzi induces exhaustion of parasite-specific T cell responses in subjects with chronic Chagas disease. The continuous inflammatory reaction due to parasite persistence in the heart also leads to necrosis and fibrosis. The complement system is a key element of the innate immune system, but recent findings have also shown that the interaction between its components and immune cell receptors might modulate several functions of the adaptive immune system. Moreover, the findings that most of immune cells can produce complement proteins and express their receptors have led to the notion that the complement system also has non canonical functions in the T cell. During human infection by T. cruzi, complement activation might play a dual role in the acute and chronic phases of Chagas disease; it is initially crucial in controlling parasitemia and might later contributes to the development of symptomatic forms of Chagas disease due to its role in T-cell regulation. Herein, we will discuss the putative role of effector complement molecules on T-cell immune exhaustion during chronic human T. cruzi infection.
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Affiliation(s)
- María Belén Caputo
- Investigation Department, Instituto Nacional de Parasitología Dr. Fatala Chaben, Buenos Aires, Argentina
| | - Josefina Elias
- Investigation Department, Instituto Nacional de Parasitología Dr. Fatala Chaben, Buenos Aires, Argentina
| | - Gonzalo Cesar
- Investigation Department, Instituto Nacional de Parasitología Dr. Fatala Chaben, Buenos Aires, Argentina
| | - María Gabriela Alvarez
- Chagas Section, Hospital Interzonal General de Agudos Eva Perón, Buenos Aires, Argentina
| | - Susana Adriana Laucella
- Investigation Department, Instituto Nacional de Parasitología Dr. Fatala Chaben, Buenos Aires, Argentina
- Chagas Section, Hospital Interzonal General de Agudos Eva Perón, Buenos Aires, Argentina
| | - María Cecilia Albareda
- Investigation Department, Instituto Nacional de Parasitología Dr. Fatala Chaben, Buenos Aires, Argentina
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Tirado TC, Moura LL, Shigunov P, Figueiredo FB. Methodological Appraisal of Literature Concerning the Analysis of Genetic Variants or Protein Levels of Complement Components on Susceptibility to Infection by Trypanosomatids: A Systematic Review. Front Immunol 2021; 12:780810. [PMID: 34899745 PMCID: PMC8656155 DOI: 10.3389/fimmu.2021.780810] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Accepted: 11/09/2021] [Indexed: 11/25/2022] Open
Abstract
Background Trypanosomatids are protozoa responsible for a wide range of diseases, with emphasis on Chagas Disease (CD) and Leishmaniasis, which are in the list of most relevant Neglected Tropical Diseases (NTD) according to World Health Organization (WHO). During the infectious process, immune system is immediately activated, and parasites can invade nucleated cells through a broad diversity of receptors. The complement system − through classical, alternative and lectin pathways − plays a role in the first line of defense against these pathogens, acting in opsonization, phagocytosis and lysis of parasites. Genetic modifications in complement genes, such as Single Nucleotide Polymorphisms (SNPs), can influence host susceptibility to these parasites and modulate protein expression. Methods In March and April 2021, a literature search was conducted at the PubMed and Google Scholar databases and the reference lists obtained were verified. After applying the inclusion and exclusion criteria, the selected studies were evaluated and scored according to eleven established criteria regarding their thematic approach and design, aiming at the good quality of publications. Results Twelve papers were included in this systematic review: seven investigating CD and five focusing on Leishmaniasis. Most articles presented gene and protein approaches, careful determination of experimental groups, and adequate choice of experimental techniques, although several of them were not up-to-date. Ten studies explored the association of polymorphisms and haplotypes with disease progression, with emphasis on lectin complement pathway genes. Decreased and increased patient serum protein levels were associated with susceptibility to CD and Visceral Leishmaniasis, respectively. Conclusion This systematic review shows the influence of genetic alterations in complement genes on the progression of several infectious diseases, with a focus on conditions caused by trypanosomatids, and contributes suggestions and evidence to improve experimental design in future research proposals.
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Affiliation(s)
- Thais Cristina Tirado
- Laboratório de Biologia Celular, Instituto Carlos Chagas, Fundação Oswaldo Cruz (FIOCRUZ), Curitiba, Brazil
| | - Larine Lowry Moura
- Laboratório de Biologia Celular, Instituto Carlos Chagas, Fundação Oswaldo Cruz (FIOCRUZ), Curitiba, Brazil
| | - Patrícia Shigunov
- Laboratório de Biologia Básica de Células-Tronco, Instituto Carlos Chagas, Fundação Oswaldo Cruz (FIOCRUZ), Curitiba, Brazil
| | - Fabiano Borges Figueiredo
- Laboratório de Biologia Celular, Instituto Carlos Chagas, Fundação Oswaldo Cruz (FIOCRUZ), Curitiba, Brazil
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Cláudia Freitas Lidani K, Andrade FA, Kozlowski RK, Luz PR, Messias-Reason IJ. Case Report: High Mannose-Binding Lectin Serum Determined by MBL2 Genotype and Risk for Clinical Progression to Chagasic Cardiomyopathy: A Case Report of Three Patients. Am J Trop Med Hyg 2019; 100:93-96. [PMID: 30526728 DOI: 10.4269/ajtmh.17-0701] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Chagas disease (CD), caused by infection with the parasite Trypanosoma cruzi, leads to severe cardiomyopathy in 20-30% of patients, whereas the remainder may stay asymptomatic and never develop cardiomyopathy or other clinical manifestations. The underlying cause for this variable outcome is not fully characterized, although previous studies have found high levels of circulating mannose-binding lectin (MBL) to be associated with cardiac failure echocardiographic changes. We report three indeterminate (asymptomatic) chronic Chagas patients who were followed up for 10 years. Two of these patients developed chronic chagasic cardiomyopathy (CCC) during this follow-up period and, when genotyped, were found to be carriers of the high MBL producer HYPA/HYPA genotype, suggesting that genetically determined high MBL serum might be associated with the risk of CCC development. These results suggest the use of MBL quantification and MBL2 genotyping as tools for clinical assessment in patients with chronic CD.
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Affiliation(s)
| | - Fabiana Antunes Andrade
- Laboratory of Molecular Immunopathology, Clinical Hospital, Federal University of Paraná, Curitiba, Brazil
| | | | - Paola Rosa Luz
- Laboratory of Molecular Immunopathology, Clinical Hospital, Federal University of Paraná, Curitiba, Brazil
| | - Iara J Messias-Reason
- Laboratory of Molecular Immunopathology, Clinical Hospital, Federal University of Paraná, Curitiba, Brazil
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7
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Acosta-Herrera M, Strauss M, Casares-Marfil D, Martín J. Genomic medicine in Chagas disease. Acta Trop 2019; 197:105062. [PMID: 31201776 DOI: 10.1016/j.actatropica.2019.105062] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Accepted: 06/11/2019] [Indexed: 02/07/2023]
Abstract
Genetic approaches have been proposed for improving the understanding of the causes of differential susceptibility to Trypanosoma cruzi infection and Chagas disease outcome. Polymorphisms in genes involved in the immune/inflammatory response are being studied in order to clarify their possible role in the occurrence or severity of the cardiac and/or gastrointestinal complications. However still today, the number of significant associated genes is limited and the pathophysiological mechanisms underlying this condition are unknown. This article review the information currently available from the published scientific literature regarding the genetic variants of molecules of the immune system and other variants that can contribute to the clinical presentation of the disease. Genomic medicine will improve our knowledge about the molecular basis of Chagas disease, will open new avenues for developing biomarkers of disease progression, new therapeutic strategies to suit the requirements of individual patients, and will contribute to the control of one of the infections with the greatest socio-economic impact in the Americas.
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Sandri TL, Andrade FA, Lidani KCF, Einig E, Boldt ABW, Mordmüller B, Esen M, Messias-Reason IJ. Human collectin-11 (COLEC11) and its synergic genetic interaction with MASP2 are associated with the pathophysiology of Chagas Disease. PLoS Negl Trop Dis 2019; 13:e0007324. [PMID: 30995222 PMCID: PMC6488100 DOI: 10.1371/journal.pntd.0007324] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Revised: 04/29/2019] [Accepted: 03/22/2019] [Indexed: 12/27/2022] Open
Abstract
Chagas Disease (CD) is an anthropozoonosis caused by Trypanosoma cruzi. With complex pathophysiology and variable clinical presentation, CD outcome can be influenced by parasite persistence and the host immune response. Complement activation is one of the primary defense mechanisms against pathogens, which can be initiated via pathogen recognition by pattern recognition molecules (PRMs). Collectin-11 is a multifunctional soluble PRM lectin, widely distributed throughout the body, with important participation in host defense, homeostasis, and embryogenesis. In complex with mannose-binding lectin-associated serine proteases (MASPs), collectin-11 may initiate the activation of complement, playing a role against pathogens, including T. cruzi. In this study, collectin-11 plasma levels and COLEC11 variants in exon 7 were assessed in a Brazilian cohort of 251 patients with chronic CD and 108 healthy controls. Gene-gene interactions between COLEC11 and MASP2 variants were analyzed. Collectin-11 levels were significantly decreased in CD patients compared to controls (p<0.0001). The allele rs7567833G, the genotypes rs7567833AG and rs7567833GG, and the COLEC11*GGC haplotype were related to T. cruzi infection and clinical progression towards symptomatic CD. COLEC11 and MASP2*CD risk genotypes were associated with cardiomyopathy (p = 0.014; OR 9.3, 95% CI 1.2–74) and with the cardiodigestive form of CD (p = 0.005; OR 15.2, 95% CI 1.7–137), suggesting that both loci act synergistically in immune modulation of the disease. The decreased levels of collectin-11 in CD patients may be associated with the disease process. The COLEC11 variant rs7567833G and also the COLEC11 and MASP2*CD risk genotype interaction were associated with the pathophysiology of CD. The heterogeneity of clinical progression during chronic Trypanosoma cruzi infection and the mechanisms determining why some individuals develop symptoms whereas others remain asymptomatic are still poorly understood. The pathogenesis of chronic Chagas Disease (CD) has been attributed mainly to the persistence of the causing parasite and the character of individual host immune responses. Collectin-11 is a host immune response molecule with affinity for sugars found on the T. cruzi’s surface. Together with mannose-binding lectin-associated serine proteases (MASPs), it triggers the host defense response against pathogens. Genetic variants and protein levels of MASP-2 and the mannose-binding lectin (MBL), a molecule structurally similar to collectin-11, have been found to be associated with susceptibility to T. cruzi infection and clinical progression to cardiomyopathy. This prompted us to investigate collectin-11 genetic variants and protein levels in 251 patients with chronic CD and 108 healthy individuals, and to examine the effect of gene interaction between COLEC11 and MASP2 risk mutations. We found an association to CD infection with COLEC11 gene variants and reduced collectin-11 levels. The concomitant presence of these genetic variants and MASP2 risk mutations greatly increased the odds for cardiomyopathy. This is the first study to reveal a role for collectin-11 and COLEC11-MASP2 gene interaction in the pathogenesis of CD.
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Affiliation(s)
- Thaisa Lucas Sandri
- Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany
- Laboratory of Molecular Immunopathology, Department of Clinical Pathology, Federal University of Paraná, Curitiba, Brazil
- * E-mail:
| | - Fabiana Antunes Andrade
- Laboratory of Molecular Immunopathology, Department of Clinical Pathology, Federal University of Paraná, Curitiba, Brazil
| | - Kárita Cláudia Freitas Lidani
- Laboratory of Molecular Immunopathology, Department of Clinical Pathology, Federal University of Paraná, Curitiba, Brazil
| | - Elias Einig
- Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany
| | - Angelica Beate Winter Boldt
- Laboratory of Molecular Immunopathology, Department of Clinical Pathology, Federal University of Paraná, Curitiba, Brazil
- Laboratory of Human Molecular Genetics, Department of Genetics, Federal University of Paraná, Curitiba, Brazil
| | | | - Meral Esen
- Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany
| | - Iara J. Messias-Reason
- Laboratory of Molecular Immunopathology, Department of Clinical Pathology, Federal University of Paraná, Curitiba, Brazil
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9
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De Bona E, Lidani KCF, Bavia L, Omidian Z, Gremski LH, Sandri TL, de Messias Reason IJ. Autoimmunity in Chronic Chagas Disease: A Road of Multiple Pathways to Cardiomyopathy? Front Immunol 2018; 9:1842. [PMID: 30127792 PMCID: PMC6088212 DOI: 10.3389/fimmu.2018.01842] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Accepted: 07/26/2018] [Indexed: 12/26/2022] Open
Abstract
Chagas disease (CD), a neglected tropical disease caused by the protozoan Trypanosoma cruzi, affects around six million individuals in Latin America. Currently, CD occurs worldwide, becoming a significant public health concern due to its silent aspect and high morbimortality rate. T. cruzi presents different escape strategies which allow its evasion from the host immune system, enabling its persistence and the establishment of chronic infection which leads to the development of chronic Chagas cardiomyopathy (CCC). The potent immune stimuli generated by T. cruzi persistence may result in tissue damage and inflammatory response. In addition, molecular mimicry between parasites molecules and host proteins may result in cross-reaction with self-molecules and consequently in autoimmune features including autoantibodies and autoreactive cells. Although controversial, there is evidence demonstrating a role for autoimmunity in the clinical progression of CCC. Nevertheless, the exact mechanism underlying the generation of an autoimmune response in human CD progression is unknown. In this review, we summarize the recent findings and hypotheses related to the autoimmune mechanisms involved in the development and progression of CCC.
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Affiliation(s)
- Elidiana De Bona
- Laboratory of Molecular Immunopathology, Department of Clinical Pathology, Federal University of Paraná, Curitiba, Brazil
| | - Kárita Cláudia Freitas Lidani
- Laboratory of Molecular Immunopathology, Department of Clinical Pathology, Federal University of Paraná, Curitiba, Brazil
| | - Lorena Bavia
- Laboratory of Molecular Immunopathology, Department of Clinical Pathology, Federal University of Paraná, Curitiba, Brazil
| | - Zahra Omidian
- Department of Pathology, Division of Immunology, School of Medicine, Johns Hopkins University, Baltimore, MD, United States
| | | | - Thaisa Lucas Sandri
- Laboratory of Molecular Immunopathology, Department of Clinical Pathology, Federal University of Paraná, Curitiba, Brazil.,Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany
| | - Iara J de Messias Reason
- Laboratory of Molecular Immunopathology, Department of Clinical Pathology, Federal University of Paraná, Curitiba, Brazil
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10
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Lidani KCF, Sandri TL, Andrade FA, Bavia L, Nisihara R, Messias-Reason IJ. Complement Factor H as a potential atherogenic marker in chronic Chagas’ disease. Parasite Immunol 2018; 40:e12537. [DOI: 10.1111/pim.12537] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Accepted: 05/10/2018] [Indexed: 02/03/2023]
Affiliation(s)
- K. C. F. Lidani
- Laboratory of Molecular Immunopathology; Clinical Hospital; Federal University of Paraná; Curitiba Brazil
| | - T. L. Sandri
- Laboratory of Molecular Immunopathology; Clinical Hospital; Federal University of Paraná; Curitiba Brazil
- Institute of Tropical Medicine; University of Tübingen; Tübingen Germany
| | - F. A. Andrade
- Laboratory of Molecular Immunopathology; Clinical Hospital; Federal University of Paraná; Curitiba Brazil
| | - L. Bavia
- Laboratory of Molecular Immunopathology; Clinical Hospital; Federal University of Paraná; Curitiba Brazil
| | - R. Nisihara
- Laboratory of Molecular Immunopathology; Clinical Hospital; Federal University of Paraná; Curitiba Brazil
| | - I. J. Messias-Reason
- Laboratory of Molecular Immunopathology; Clinical Hospital; Federal University of Paraná; Curitiba Brazil
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11
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Binding capacity of mannose-binding lectin (MBL) is associated with the severity of chronic Chagas cardiomyopathy. Parasitol Int 2018; 67:593-596. [PMID: 29775825 DOI: 10.1016/j.parint.2018.05.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2018] [Revised: 05/14/2018] [Accepted: 05/14/2018] [Indexed: 11/20/2022]
Abstract
Chagas disease (CD) is a global problem. Currently, it affects approximately 15 million individuals in Latin America. It is well know that the human immune response is related to different clinical manifestations. Mannose binding lectin (MBL) plays an important role in innate immunity, and it mediates the phagocytosis and complement-mediated destruction of pathogens. The binding capacity is enhanced by the oligomerization of MBL. In this study, we evaluated the serum concentration and the binding capacity of MBL in patients with chronic chagasic cardiomyopathy. A total of 77 patients with chronic CD were included with indeterminate (n = 19), mild cardiac (n = 29) and severe cardiac (n = 29) forms. The serum concentration and the binding capacity were measured using enzyme-linked immunosorbent assays (ELISA). There was no significant difference in the serum MBL levels between the groups of patients. However, we found a relationship between the binding capacity and the groups studied. Our results suggest that binding capacity of MBL could be an indicator of clinical manifestation in Chronic Chagas cardiomyopathy. Furthermore, combined with the Mannose Binding Index results in a useful clinical tool for management of Chronic Chagas Patients.
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12
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Fraser RS, Lumsden JS, Lillie BN. Identification of polymorphisms in the bovine collagenous lectins and their association with infectious diseases in cattle. Immunogenetics 2018; 70:533-546. [PMID: 29744529 PMCID: PMC6061482 DOI: 10.1007/s00251-018-1061-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Accepted: 05/01/2018] [Indexed: 12/30/2022]
Abstract
Infectious diseases are a significant issue in animal production systems, including both the dairy and beef cattle industries. Understanding and defining the genetics of infectious disease susceptibility in cattle is an important step in the mitigation of their impact. Collagenous lectins are soluble pattern recognition receptors that form an important part of the innate immune system, which serves as the first line of host defense against pathogens. Polymorphisms in the collagenous lectin genes have been shown in previous studies to contribute to infectious disease susceptibility, and in cattle, mutations in two collagenous lectin genes (MBL1 and MBL2) are associated with mastitis. To further characterize the contribution of variation in the bovine collagenous lectins to infectious disease susceptibility, we used a pooled NGS approach to identify short nucleotide variants (SNVs) in the collagenous lectins (and regulatory DNA) of cattle with (n = 80) and without (n = 40) infectious disease. Allele frequency analysis identified 74 variants that were significantly (p < 5 × 10−6) associated with infectious disease, the majority of which were clustered in a 29-kb segment upstream of the collectin locus on chromosome 28. In silico analysis of the functional effects of all the variants predicted 11 SNVs with a deleterious effect on protein structure and/or function, 148 SNVs that occurred within potential transcription factor binding sites, and 31 SNVs occurring within potential miRNA binding elements. This study provides a detailed look at the genetic variation of the bovine collagenous lectins and identifies potential genetic markers for infectious disease susceptibility.
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Affiliation(s)
- R S Fraser
- Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada
| | - J S Lumsden
- Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada.,St. George's University, True Blue, Grenada
| | - B N Lillie
- Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada.
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13
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Ferreira BL, Ferreira ÉR, de Brito MV, Salu BR, Oliva MLV, Mortara RA, Orikaza CM. BALB/c and C57BL/6 Mice Cytokine Responses to Trypanosoma cruzi Infection Are Independent of Parasite Strain Infectivity. Front Microbiol 2018; 9:553. [PMID: 29662478 PMCID: PMC5890190 DOI: 10.3389/fmicb.2018.00553] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Accepted: 03/12/2018] [Indexed: 11/13/2022] Open
Abstract
Trypanosoma cruzi is the etiologic agent of Chagas’ disease, which affects 6–7 million people worldwide. Different strains of T. cruzi present specific genotypic and phenotypic characteristics that affect the host–pathogen interactions, and thus, the parasite has been classified into six groups (TcI to TcVI). T. cruzi infection presents two clinical phases, acute and chronic, both with distinct characteristics and important participation by the immune system. However, the specific contributions of parasite and host factors in the disease phases are not yet fully understood. The murine model for Chagas’ disease is well-established and reproduces important features of the human infection, providing an experimental basis for the study of host lineages and parasite strains. Thus, we evaluated acute and chronic infection by the G (TcI) and CL (TcVI) strains of T. cruzi, which have distinct tropisms and infectivity, in two inbred mice lineages (C57BL/6 and BALB/c) that display variable degrees of susceptibility to different T. cruzi strains. Analysis of the parasite loads in host tissues by qPCR showed that CL strain established an infection faster than the G strain; at the same time, the response in BALB/c mice, although diverse in terms of cytokine secretion, was initiated earlier than that in C57BL/6 mice. At the parasitemia peak in the acute phase, we observed, either by confocal microscopy or by qPCR, that the infection was disseminated in all groups analyzed, with some differences concerning parasite tropism; at this point, all animals responded to infection by increasing the serum concentrations of cytokines. However, BALB/c mice seemed to better regulate the immune response than C57BL/6 mice. Indeed, in the chronic phase, C57BL/6 mice still presented exacerbated cytokine and chemokine responses. In summary, our results indicate that in these experimental models, the deregulation of immune response that is typical of chronic Chagas’ disease may be due to control loss over pro- and anti-inflammatory cytokines early in the acute phase of the disease, depending primarily on the host background rather than the parasite strain.
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Affiliation(s)
- Bianca L Ferreira
- Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Éden R Ferreira
- Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Marlon V de Brito
- Departamento de Bioquímica, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Bruno R Salu
- Departamento de Bioquímica, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Maria L V Oliva
- Departamento de Bioquímica, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Renato A Mortara
- Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Cristina M Orikaza
- Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
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14
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Arroyo-Olarte RD, Martínez I, Cruz-Rivera M, Mendlovic F, Espinoza B. Complement system contributes to modulate the infectivity of susceptible TcI strains of Trypanosoma cruzi. Mem Inst Oswaldo Cruz 2018. [PMID: 29513875 PMCID: PMC5851054 DOI: 10.1590/0074-02760170332] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
BACKGROUND Trypanosoma cruzi is a protozoan parasite and an etiological agent of Chagas disease. There is a wide variability in the clinical outcome of its infection, ranging from asymptomatic individuals to those with chronic fatal mega syndromes. Both parasite and host factors, as well as their interplay, are thought to be involved in the process. OBJECTIVES To evaluate the resistance to complement-mediated killing in two T. cruzi TcI strains with differential virulence and the subsequent effect on their infectivity in mammalian cells. METHODS Tissue-culture derived trypomastigotes of both strains were incubated in guinea pig serum and subjected to flow cytometry in order to determine their viability and complement activations. Trypomastigotes were also incubated on host cells monolayers in the presence of serum, and infectivity was evaluated under different conditions of complement pathway inhibition. Relative expression of the main parasite-specific complement receptors between the two strains was assessed by quantitative real-time polymerase chain reaction. FINDINGS In this work, we showed that two TcI strains, one with lower virulence (Ninoa) compared to the other (Qro), differ in their resistance to the lytic activity of complement system, hence causing a compromised ability of Ninoa strain to invade mammalian cells. These results correlate with the three-fold lower messenger RNA (mRNA) levels of complement regulatory protein (CRP), trypomastigote-decay acceleration factor (T-DAF), and complement C2 receptor inhibitor trispanning (CRIT) in Ninoa compared to those in Qro. On the other hand, calreticulin (CRT) mRNA and surface protein levels were higher in Ninoa strain and promoted its infectivity when the lectin pathway of the complement system was inhibited. MAIN CONCLUSIONS This work suggests the complex interplay of CRP, T-DAF, CRIT, and CRT, and the diagnostic value of mRNA levels in the assessment of virulence potential of T. cruzi strains, particularly when dealing with isolates with similar genetic background.
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Affiliation(s)
- Ruben D Arroyo-Olarte
- Universidad Nacional Autónoma de México, Instituto de Investigaciones Biomedicas, Departamento de Immunología, Ciudad de Mexico, Mexico
| | - Ignacio Martínez
- Universidad Nacional Autónoma de México, Instituto de Investigaciones Biomedicas, Departamento de Immunología, Ciudad de Mexico, Mexico
| | - Mayra Cruz-Rivera
- Universidad Nacional Autónoma de México, Facultad de Medicina, Departamento de Microbiología y Parasitología, Ciudad de Mexico, Mexico
| | - Fela Mendlovic
- Universidad Nacional Autónoma de México, Facultad de Medicina, Departamento de Microbiología y Parasitología, Ciudad de Mexico, Mexico.,Universidad Anahuac, Facultad de Ciencias de la Salud, Mexico Norte, Estado de Mexico, Mexico
| | - Bertha Espinoza
- Universidad Nacional Autónoma de México, Instituto de Investigaciones Biomedicas, Departamento de Immunología, Ciudad de Mexico, Mexico
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15
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Sandri TL, Lidani KCF, Andrade FA, Meyer CG, Kremsner PG, de Messias-Reason IJ, Velavan TP. Human complement receptor type 1 (CR1) protein levels and genetic variants in chronic Chagas Disease. Sci Rep 2018; 8:526. [PMID: 29323238 PMCID: PMC5765048 DOI: 10.1038/s41598-017-18937-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Accepted: 12/19/2017] [Indexed: 11/13/2022] Open
Abstract
Complement is an essential element in both innate and acquired immunity contributing to the immunopathogenesis of many disorders, including Chagas Disease (CD). Human complement receptor 1 (CR1) plays a role in the clearance of complement opsonized molecules and may facilitate the entry of pathogens into host cells. Distinct CR1 exon 29 variants have been found associated with CR1 expression levels, increased susceptibility and pathophysiology of several diseases. In this study, CR1 plasma levels were assessed by ELISA and CR1 variants in exon 29 by sequencing in a Brazilian cohort of 232 chronic CD patients and 104 healthy controls. CR1 levels were significantly decreased in CD patients compared to controls (p < 0.0001). The CR1 rs1704660G, rs17047661G and rs6691117G variants were significantly associated with CD and in high linkage disequilibrium. The CR1*AGAGTG haplotype was associated with T. cruzi infection (p = 0.035, OR 3.99, CI 1.1-14.15) whereas CR1*AGGGTG was related to the risk of chagasic cardiomyopathy (p = 0.028, OR 12.15, CI 1.13-113). This is the first study that provides insights on the role of CR1 in development and clinical presentation of chronic CD.
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Affiliation(s)
- Thaisa Lucas Sandri
- Laboratory of Molecular Immunopathology, Federal University of Paraná, Curitiba, Brazil
- Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany
| | | | | | - Christian G Meyer
- Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany
- Faculty of Medicine, Duy Tan University, Da Nang, Vietnam
- Vietnamese - German Center for Medical Research, Hanoi, Vietnam
| | - Peter G Kremsner
- Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany
| | | | - Thirumalaisamy P Velavan
- Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany.
- Faculty of Medicine, Duy Tan University, Da Nang, Vietnam.
- Vietnamese - German Center for Medical Research, Hanoi, Vietnam.
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16
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Lidani KCF, Bavia L, Ambrosio AR, de Messias-Reason IJ. The Complement System: A Prey of Trypanosoma cruzi. Front Microbiol 2017; 8:607. [PMID: 28473804 PMCID: PMC5397499 DOI: 10.3389/fmicb.2017.00607] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Accepted: 03/24/2017] [Indexed: 12/27/2022] Open
Abstract
Trypanosoma cruzi is a protozoan parasite known to cause Chagas disease (CD), a neglected sickness that affects around 6-8 million people worldwide. Originally, CD was mainly found in Latin America but more recently, it has been spread to countries in North America, Asia, and Europe due the international migration from endemic areas. Thus, at present CD represents an important concern of global public health. Most of individuals that are infected by T. cruzi may remain in asymptomatic form all lifelong, but up to 40% of them will develop cardiomyopathy, digestive mega syndromes, or both. The interaction between the T. cruzi infective forms and host-related immune factors represents a key point for a better understanding of the physiopathology of CD. In this context, the complement, as one of the first line of host defense against infection was shown to play an important role in recognizing T. cruzi metacyclic trypomastigotes and in controlling parasite invasion. The complement consists of at least 35 or more plasma proteins and cell surface receptors/regulators, which can be activated by three pathways: classical (CP), lectin (LP), and alternative (AP). The CP and LP are mainly initiated by immune complexes or pathogen-associated molecular patterns (PAMPs), respectively, whereas AP is spontaneously activated by hydrolysis of C3. Once activated, several relevant complement functions are generated which include opsonization and phagocytosis of particles or microorganisms and cell lysis. An important step during T. cruzi infection is when intracellular trypomastigotes are release to bloodstream where they may be target by complement. Nevertheless, the parasite uses a sequence of events in order to escape from complement-mediated lysis. In fact, several T. cruzi molecules are known to interfere in the initiation of all three pathways and in the assembly of C3 convertase, a key step in the activation of complement. Moreover, T. cruzi promotes secretion of plasma membrane-derived vesicles from host cells, which prevent the activity of C3 convertase C4b2a and thereby may hinder complement. In this review, we aim to present an overview on the strategies used by T. cruzi in order to circumvent the activation of complement and, consequently, its biological effects.
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Affiliation(s)
| | | | | | - Iara J. de Messias-Reason
- Laboratory of Molecular Immunopathology, Clinical Hospital, Federal University of ParanáCuritiba, Brazil
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17
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Balouz V, Agüero F, Buscaglia CA. Chagas Disease Diagnostic Applications: Present Knowledge and Future Steps. ADVANCES IN PARASITOLOGY 2016; 97:1-45. [PMID: 28325368 PMCID: PMC5363286 DOI: 10.1016/bs.apar.2016.10.001] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Chagas disease, caused by the protozoan Trypanosoma cruzi, is a lifelong and debilitating illness of major significance throughout Latin America and an emergent threat to global public health. Being a neglected disease, the vast majority of Chagasic patients have limited access to proper diagnosis and treatment, and there is only a marginal investment into R&D for drug and vaccine development. In this context, identification of novel biomarkers able to transcend the current limits of diagnostic methods surfaces as a main priority in Chagas disease applied research. The expectation is that these novel biomarkers will provide reliable, reproducible and accurate results irrespective of the genetic background, infecting parasite strain, stage of disease, and clinical-associated features of Chagasic populations. In addition, they should be able to address other still unmet diagnostic needs, including early detection of congenital T. cruzi transmission, rapid assessment of treatment efficiency or failure, indication/prediction of disease progression and direct parasite typification in clinical samples. The lack of access of poor and neglected populations to essential diagnostics also stresses the necessity of developing new methods operational in point-of-care settings. In summary, emergent diagnostic tests integrating these novel and tailored tools should provide a significant impact on the effectiveness of current intervention schemes and on the clinical management of Chagasic patients. In this chapter, we discuss the present knowledge and possible future steps in Chagas disease diagnostic applications, as well as the opportunity provided by recent advances in high-throughput methods for biomarker discovery.
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Affiliation(s)
- Virginia Balouz
- Instituto de Investigaciones Biotecnológicas - Instituto Tecnológico de Chascomús (IIB-INTECH), Universidad Nacional de San Martín (UNSAM) - Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), San Martín, B 1650 HMP, Buenos Aires, Argentina
| | - Fernán Agüero
- Instituto de Investigaciones Biotecnológicas - Instituto Tecnológico de Chascomús (IIB-INTECH), Universidad Nacional de San Martín (UNSAM) - Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), San Martín, B 1650 HMP, Buenos Aires, Argentina
| | - Carlos A. Buscaglia
- Instituto de Investigaciones Biotecnológicas - Instituto Tecnológico de Chascomús (IIB-INTECH), Universidad Nacional de San Martín (UNSAM) - Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), San Martín, B 1650 HMP, Buenos Aires, Argentina
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18
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Chemokines and Heart Disease: A Network Connecting Cardiovascular Biology to Immune and Autonomic Nervous Systems. Mediators Inflamm 2016; 2016:5902947. [PMID: 27242392 PMCID: PMC4868905 DOI: 10.1155/2016/5902947] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Revised: 03/25/2016] [Accepted: 04/03/2016] [Indexed: 02/07/2023] Open
Abstract
Among the chemokines discovered to date, nineteen are presently considered to be relevant in heart disease and are involved in all stages of cardiovascular response to injury. Chemokines are interesting as biomarkers to predict risk of cardiovascular events in apparently healthy people and as possible therapeutic targets. Moreover, they could have a role as mediators of crosstalk between immune and cardiovascular system, since they seem to act as a “working-network” in deep linkage with the autonomic nervous system. In this paper we will describe the single chemokines more involved in heart diseases; then we will present a comprehensive perspective of them as a complex network connecting the cardiovascular system to both the immune and the autonomic nervous systems. Finally, some recent evidences indicating chemokines as a possible new tool to predict cardiovascular risk will be described.
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19
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Li E, Tako EA, Singer SM. Complement Activation by Giardia duodenalis Parasites through the Lectin Pathway Contributes to Mast Cell Responses and Parasite Control. Infect Immun 2016; 84:1092-1099. [PMID: 26831470 PMCID: PMC4807472 DOI: 10.1128/iai.00074-16] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Accepted: 01/26/2016] [Indexed: 11/20/2022] Open
Abstract
Infection with Giardia duodenalis is one of the most common causes of diarrheal disease in the world. While numerous studies have identified important contributions of adaptive immune responses to parasite control, much less work has examined innate immunity and its connections to the adaptive response during this infection. We explored the role of complement in immunity to Giardia using mice deficient in mannose-binding lectin (Mbl2) or complement factor 3a receptor (C3aR). Both strains exhibited delayed clearance of parasites and a reduced ability to recruit mast cells in the intestinal submucosa. C3aR-deficient mice had normal production of antiparasite IgA, butex vivo T cell recall responses were impaired. These data suggest that complement is a key factor in the innate recognition of Giardia and that recruitment of mast cells and activation of T cell immunity through C3a are important for parasite control.
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Affiliation(s)
- Erqiu Li
- Department of Biology, Georgetown University, Washington, DC, USA
| | - Ernest A Tako
- Department of Biology, Georgetown University, Washington, DC, USA
| | - Steven M Singer
- Department of Biology, Georgetown University, Washington, DC, USA
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