Genetic variants in the chemokines and chemokine receptors in Chagas disease

Cytokine profile levels and their relationship with parasitemia and cardiomyopathy in people with Chagas disease in Spain. A prospective observational study

Immunoregulatory networks may have a role in controlling parasitemia in the chronic phase of human Chagas disease. The aim was to describe the serum cytokine profile of Trypanosoma cruzi in chronically infected patients and to evaluate its relationship with parasitemia and Chagas cardiomyopathy.This prospective observational study included adult patients with chronic Chagas disease. Demographic and clinical data were collected, and peripheral blood samples were used to perform T. cruzi real-time polymerase chain reaction (RT-PCR) and determine the serum cytokine profile.Fifty-eight patients were included; 17 (29.3%) had positive RT-PCR results. This group had a higher median concentration of TNF-α (p = 0.003), IL-6 (p = 0.021), IL-4 (p = 0.031), IL-1β (p = 0.036), and IL-17A (p = 0.043) than those with a negative RT-PCR. Patients with cardiac involvement had a higher median concentration of IL-5 (p = 0.016) than those without.These results reinforce the key role that cytokines play in Chagas disease patients with parasitemia and cardiac involvement.

Narrowing the Relationship between Human CCR5 Gene Polymorphisms and Chagas Disease: Systematic Review and Meta-Analysis

Our aim was to carry out a qualitative and quantitative synthesis of the influence of CCR5 genetic variants on Chagas disease (CD) through a systematic review. A total of 1197 articles were analyzed, and eleven were included in the review. A meta-analysis was conducted along with principal component analyses (PCAs). The polymorphisms found were analyzed using the SNP2TFBS tool to identify possible variants that influence the interaction with gene binding sites. Eleven studied variants were identified: rs2856758, rs2734648, rs1799987, rs1799988, rs41469351, rs1800023, rs1800024, Δ32/rs333, rs3176763, rs3087253 and rs11575815. The studies analyzed were published between 2001 and 2019, conducted in Argentina, Brazil, Spain, Colombia and Venezuela, and included Argentine, Brazilian, Colombian, Peruvian and Venezuelan patients. Eight polymorphisms were subjected to the meta-analysis, of which six were associated with the development of the cardiac form of CD: rs1799987-G/G and G/A in the dominance model and G/G in the recessiveness model; rs2856758-A/G in the codominance model; rs2734648-T/T and T/G in the dominance model; rs1799988-T/T in both the codominance and recessiveness models; rs1800023-G allele and the G/G genotype in the codominance and recessiveness models, and the G/G and G/A genotypes in the dominance model; and rs1800024-T allele. The PCA analyses were able to indicate the relationships between the alleles and the genotypes of the polymorphisms. The SNP2TFBS tool identified rs1800023 as an influencer of the Spi1 transcription factor (p < 0.05). A correlation was established between the alleles associated with the cardiac form of CD in this review, members of the C haplotype of the gene (HHC-TGTG), and the cardiac form of CD.

Chronic Trypanosoma cruzi infection activates the TWEAK/Fn14 axis in cardiac myocytes and fibroblasts driving structural and functional changes that affect the heart

Sustained interaction between the cytokine tumor necrosis factor-like weak inducer of apoptosis (TWEAK) and its functional receptor, fibroblast growth factor-inducible 14 (Fn14), has been linked to cardiovascular disorders. Chagas cardiomyopathy, elicited by Trypanosoma cruzi infection, is associated with chronic inflammation, fibrosis and hypertrophy. This study aimed to explore the involvement of the TWEAK/Fn 14 axis in development of Chagas heart disease. Parasite infection in vitro triggered Fn14 overexpression in atrial HL-1 myocytes and cardiac MCF fibroblasts. Fn14 levels were also increased in heart tissue from C57BL/6 mice at 130 days post-infection, particularly in myocytes and fibroblasts. Concurrently, TWEAK expression in circulating monocytes from this group was higher than that determined in uninfected controls. TWEAK/Fn14 interaction was functional in myocytes and fibroblasts isolated from infected hearts, leading to TNF receptor-associated factor 2 (TRAF2)-mediated activation of nuclear factor kappa B (NFκB) signaling. Ex vivo stimulation of both cell types with recombinant TWEAK for 24 h boosted the NFκB-regulated production of proinflammatory/profibrotic mediators (IL-1β, IL-6, TNF-α, IL-8, CCL2, CCL5, MMP-2, MMP-9, ICAM-1, E-selectin) involved in chronic T. cruzi cardiomyopathy. We further evaluated the therapeutic potential of the soluble decoy receptor Fn14-Fc to interfere with TWEAK/Fn14-dependent pathogenic activity. Fn14-Fc treatment of chronically infected mice was effective in neutralizing the ligand and reverting electrocardiographic abnormalities, maladaptive inflammation, adverse remodeling and hypertrophy in myocardium. Altogether, these findings suggest that sustained TWEAK/Fn14 induction by persistent T. cruzi infection is implicated in cardiopathogenesis and make TWEAK/Fn14 axis a promising target for the treatment of chronic Chagas heart disease.

Cytokine Networks as Targets for Preventing and Controlling Chagas Heart Disease

Chagas disease, a neglected disease caused by the protozoan Trypanosoma cruzi, is endemic in 21 Latin American countries, affecting 6-8 million people. Increasing numbers of Chagas disease cases have also been reported in non-endemic countries due to migration, contamination via blood transfusions or organ transplantation, characterizing Chagas as an emerging disease in such regions. While most individuals in the chronic phase of Chagas disease remain in an asymptomatic clinical form named indeterminate, approximately 30% of the patients develop a cardiomyopathy that is amongst the deadliest cardiopathies known. The clinical distinctions between the indeterminate and the cardiac clinical forms are associated with different immune responses mediated by innate and adaptive cells. In this review, we present a collection of studies focusing on the human disease, discussing several aspects that demonstrate the association between chemokines, cytokines, and cytotoxic molecules with the distinct clinical outcomes of human infection with Trypanosoma cruzi. In addition, we discuss the role of gene polymorphisms in the transcriptional control of these immunoregulatory molecules. Finally, we discuss the potential application of cytokine expression and gene polymorphisms as markers of susceptibility to developing the severe form of Chagas disease, and as targets for disease control.

CCR5-Δ32 biology, gene editing, and warnings for the future of CRISPR-Cas9 as a human and humane gene editing tool

Background

Biomedical technologies have not just improved human health but also assisted in the creation of human life. Since the first birth of a healthy baby by in vitro fertilization (IVF) 40 years ago, IVF has been the mainstay treatment for couples struggling with infertility. This technology, in addition to increasingly accessible genetic testing, has made it possible for countless couples to have children. Since CRISPR-Cas9 gene editing was described in 2015, its potential for targeting genetic diseases has been much anticipated. However, the potential of using CRISPR-Cas9 for human germline modification has led to many fears of "designer babies" and widespread concerns for the impact of this technology on human evolution and its implications in Social Darwinism. In addition to these ethical/moral concerns, there remain many unknowns about CRISPR-Cas9 technology and endless unanticipated consequence to gene editing.

Methods

In this paper, we analyze the current progresses of CRISPR-Cas9 technology and discuss the theoretical advantages of certain allelic variances in the C-C chemokine receptor 5 gene (CCR5) in the setting of recent ethical/moral concerns regarding gene editing using the CRISPR-Cas9 system.

Results

These uncertainties have been highlighted recently by the birth of Chinese twins whose C-C chemokine receptor 5 (CCR5) gene had been inactivated via CRISPR-Cas9 to be theoretically protective against HIV infection. CCR5 signaling is critical for the successful infection of human immunodeficiency virus (HIV) and people with homozygous inactivating CCR5-Δ32 mutations have been shown to be protected against HIV infection. Those with the CCR5-Δ32/Δ32 mutation also have greater neuroplasticity, allowing for improved recovery from neurological trauma, and decreased Chagas cardiomyopathy. However, the CCR5-Δ32/Δ32 mutation has also been associated with earlier clinical manifestations for West Nile infection, ambiguous effects on osteoclast function, and a four-fold increased mortality from influenza infection. These detrimental health impacts, in addition to the confounding factor that these CRISPR babies do not carry this exact CCR5-Δ32/Δ32 mutation, lead to many questions regarding the children's future health and the moral conundrum of their birth. The creation and birth of these babies was not completed with any scientific, ethical, or governmental oversight, which has spurned the acceleration of talks regarding global regulations for human genetic editing.

Conclusions

Although we can try to regulate for ethical, health-related only use of this technology, moral and governmental oversights need to be supplemented by technical regulations. For instance, whole genome sequencing needs to be used to eliminate off-target mutations that could affect the health and safety of infants born to this process. Like Pandora's Box, we cannot pretend to forget CRISPR-Cas9 technology, all we can do is ensure a safe, moral, and equitable used of this technology.

CCR5 and CCR5Δ32 in bacterial and parasitic infections: Thinking chemokine receptors outside the HIV box

The CCR5 molecule was reported in 1996 as the main HIV-1 co-receptor. In that same year, the CCR5Δ32 genetic variant was described as a strong protective factor against HIV-1 infection. These findings led to extensive research regarding the CCR5, culminating in critical scientific advances, such as the development of CCR5 inhibitors for the treatment of HIV infection. Recently, the research landscape surrounding CCR5 has begun to change. Different research groups have realized that, since CCR5 has such important effects in the chemokine system, it could also affect other different physiological systems. Therefore, the effect of reduced CCR5 expression due to the presence of the CCR5Δ32 variant began to be further studied. Several studies have investigated the role of CCR5 and the impacts of CCR5Δ32 on autoimmune and inflammatory diseases, various types of cancer, and viral diseases. However, the role of CCR5 in diseases caused by bacteria and parasites is still poorly understood. Therefore, the aim of this article is to review the role of CCR5 and the effects of CCR5Δ32 on bacterial (brucellosis, osteomyelitis, pneumonia, tuberculosis and infection by Chlamydia trachomatis) and parasitic infections (toxoplasmosis, leishmaniasis, Chagas disease and schistosomiasis). Basic information about each of these infections was also addressed. The neglected role of CCR5 in fungal disease and emerging studies regarding the action of CCR5 on regulatory T cells are briefly covered in this review. Considering the "renaissance of CCR5 research," this article is useful for updating researchers who develop studies involving CCR5 and CCR5Δ32 in different infectious diseases.

Metabolomics as an Approach to Characterise the Contrasting Roles of CCR5 in the Presence and Absence of Disease

Chemokine receptors such as C-C chemokine receptor 5 (CCR5) are activated through interaction with their ligands and are well known for their role in chemotaxis and signal transduction. While serving these roles, cellular responses are effected, hence the immune function of these molecules is established. Given the role of CCR5 in immune function and that the immune and metabolic systems are interlinked, subsequent immune-directed changes should be measurable at a metabolic level. Numerous investigations have reported on metabolic changes associated with CCR5 status in the presence of disease, so as to understand whether specific CCR5 genotypes, frequency and/or levels offer protection to the host or not. However, these metabolic changes were recorded using older conventional techniques. Depending on certain factors such as the disease model, the geography of the samples and/or the ethnic group under study, the role of CCR5 in disease differs. In addition, little is known about CCR5's role in the absence of an enhanced inflammatory state, such as when infection persists. Metabolomics is defined as the study of metabolites and informs on metabolic changes within living organisms as induced by various stimuli, such as the interaction of CCR5 with its ligand. Since metabolomics reflects the underlying biochemical activity and state of cells/tissues, this review proposes it as a tool to clarify the contrasting roles of CCR5.

Genomic medicine in Chagas disease

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.

Congenital Transmission of Trypanosoma cruzi: A Review About the Interactions Between the Parasite, the Placenta, the Maternal and the Fetal/Neonatal Immune Responses

Chagas disease (CD), caused by the protozoan parasite Trypanosoma cruzi, is considered a neglected tropical disease by the World Health Organization. Congenital transmission of CD is an increasingly relevant public health problem. It progressively becomes the main transmission route over others and can occur in both endemic and non-endemic countries. Though most congenitally infected newborns are asymptomatic at birth, they display higher frequencies of prematurity, low birth weight, and lower Apgar scores compared to uninfected ones, and some suffer from severe symptoms. If not diagnosed and treated, infected newborns are at risk of developing disabling and life-threatening chronic pathologies later in life. The success or failure of congenital transmission depends on interactions between the parasite, the placenta, the mother, and the fetus. We review and discuss here the current knowledge about these parameters, including parasite virulence factors such as exovesicles, placental tropism, potential placental defense mechanisms, the placental transcriptome of infected women, gene polymorphism, and the maternal and fetal/neonatal immune responses, that might modulate the risk of T. cruzi congenital transmission.

Association study between CCR2-CCR5 genes polymorphisms and chronic Chagas heart disease in Wichi and in admixed populations from Argentina

Several studies have proposed different genetic markers of susceptibility to develop chronic Chagas cardiomyopathy (CCC). Many genes may be involved, each one making a small contribution. For this reason, an appropriate approach for this problematic is to study a large number of single nucleotide polymorphisms (SNPs) in individuals sharing a genetic background. Our aim was to analyze two CCR2 and seven CCR5 SNPs and their association to CCC in Argentina. A case-control study was carried out in 480 T. cruzi seropositive adults from Argentinean Gran Chaco endemic region (Wichi and Creole) and patients from Buenos Aires health centres. They were classified according to the Consensus on Chagas-Mazza Disease as non-demonstrated (non-DC group) or demonstrated (DC group) cardiomyopathy, i.e. asymptomatic or with CCC patients, respectively. Since, after allelic analysis, 2 out of 9 studied SNPs did not fit Hardy–Weinberg equilibrium in the unaffected non-DC group from Wichi patients, we analyzed them as a separate population. Only rs1800024T and rs41469351T in CCR5 gene showed significant differences within non-Wichi population (Creole + patients from Buenos Aires centres), being the former associated to protection, and the latter to risk of CCC. No evidence of association was observed between any of the analyzed CCR2-CCR5 gene polymorphisms and the development of CCC; however, the HHE haplotype was associated with protection in Wichi population. Our findings support the hypothesis that CCR2-CCR5 genes and their haplotypes are associated with CCC; however, depending on the population studied, different associations can be found. Therefore, the evolutionary context, in which the genes or haplotypes are associated with diseases, acquires special relevance.

Chagas disease caused by the infection with the protozoan Trypanosoma cruzi is endemic in Latin America. In Argentina, it is estimated 1.5 million patients have Chagas disease and 2.2 million people in risk of T. cruzi infection. The endemic area covers the north of the country where the conditions, such as high levels of poverty and social exclusion and low population density, mostly rural, favor T. cruzi infection. Most affected people remains asymptomatic after infection for the rest of their lives, but around one third of infected people may develop clinical symptoms of visceral damage. Chronic Chagas Cardiomyopathy (CCC), the most frequent and severe consequence of the chronic infection by T. cruzi, is manifested predominately as an arrhythmogenic cardiomyopathy. The pathogenesis of CCC is not completely understood, but it is believed that the human genetic variation may be a determinant factor of disease progression. We studied in Wichi and in admixed populations from Argentina the CCR2-CCR5 genes, two CC chemokine receptors involved in the trafficking of several immune cells and in the pathogenesis of cardiovascular diseases. Our results showed that CCR2-CCR5 genes are associated with CCC and highlight the relevance of the evolutionary context in which disease-associated genes are found.

Identification of Crucial Genes and Pathways in Human Arrhythmogenic Right Ventricular Cardiomyopathy by Coexpression Analysis

As one common disease causing young people to die suddenly due to cardiac arrest, arrhythmogenic right ventricular cardiomyopathy (ARVC) is a disorder of heart muscle whose progression covers one complicated gene interaction network that influence the diagnosis and prognosis of it. In our research, differentially expressed genes (DEGs) were screened, and we established a weighted gene coexpression network analysis (WGCNA) and gene set net correlations analysis (GSNCA) for identifying crucial genes as well as pathways related to ARVC pathogenic mechanism (n = 12). In the research, the results demonstrated that there were 619 DEGs in total between non-failing donor myocardial samples and ARVC tissues (FDR < 0.05). WGCNA analysis identified the two gene modules (brown and turquoise) as being most significantly associated with ARVC state. Then the ARVC-related four key biological pathways (cytokine–cytokine receptor interaction, chemokine signaling pathway, neuroactive ligand receptor interaction, and JAK-STAT signaling pathway) and four hub genes (CXCL2, TNFRSF11B, LIFR, and C5AR1) in ARVC samples were further identified by GSNCA method. Finally, we used t-test and receiver operating characteristic (ROC) curves for validating hub genes, results showed significant differences in t-test and their AUC areas all greater than 0.8. Together, these results revealed that the new four hub genes as well as key pathways that might be involved into ARVC diagnosis. Even though further experimental validation is required for the implication by association, our findings demonstrate that the computational methods based on systems biology might complement the traditional gene-wide approaches, as such, might offer a new insight in therapeutic intervention within rare diseases of people like ARVC.

Disease Tolerance and Pathogen Resistance Genes May Underlie Trypanosoma cruzi Persistence and Differential Progression to Chagas Disease Cardiomyopathy

Chagas disease is caused by infection with the protozoan Trypanosoma cruzi and affects over 8 million people worldwide. In spite of a powerful innate and adaptive immune response in acute infection, the parasite evades eradication, leading to a chronic persistent infection with low parasitism. Chronically infected subjects display differential patterns of disease progression. While 30% develop chronic Chagas disease cardiomyopathy (CCC)—a severe inflammatory dilated cardiomyopathy—decades after infection, 60% of the patients remain disease-free, in the asymptomatic/indeterminate (ASY) form, and 10% develop gastrointestinal disease. Infection of genetically deficient mice provided a map of genes relevant for resistance to T. cruzi infection, leading to the identification of multiple genes linked to survival to infection. These include pathogen resistance genes (PRG) needed for intracellular parasite destruction, and genes involved in disease tolerance (protection against tissue damage and acute phase death—DTG). All identified DTGs were found to directly or indirectly inhibit IFN-γ production or Th1 differentiation. We hypothesize that the absolute need for DTG to control potentially lethal IFN-γ PRG activity leads to T. cruzi persistence and establishment of chronic infection. IFN-γ production is higher in CCC than ASY patients, and is the most highly expressed cytokine in CCC hearts. Key DTGs that downmodulate IFN-γ, like IL-10, and Ebi3/IL27p28, are higher in ASY patients. Polymorphisms in PRG and DTG are associated with differential disease progression. We thus hypothesize that ASY patients are disease tolerant, while an imbalance of DTG and IFN-γ PRG activity leads to the inflammatory heart damage of CCC.

Genetic Polymorphism at CCL5 Is Associated With Protection in Chagas' Heart Disease: Antagonistic Participation of CCR1+ and CCR5+ Cells in Chronic Chagasic Cardiomyopathy

Chronic cardiomyopathy is the main clinical manifestation of Chagas disease (CD), a disease caused by Trypanosoma cruzi infection. A hallmark of chronic chagasic cardiomyopathy (CCC) is a fibrogenic inflammation mainly composed of CD8⁺ and CD4⁺ T cells and macrophages. CC-chemokine ligands and receptors have been proposed to drive cell migration toward the heart tissue of CD patients. Single nucleotide polymorphisms (SNPs) in CC-chemokine ligand and receptor genes may determine protein expression. Herein, we evaluated the association of SNPs in the CC-chemokines CCL2 (rs1024611) and CCL5 (rs2107538, rs2280788) and the CCL5/RANTES receptors CCR1 (rs3181077, rs1491961, rs3136672) and CCR5 (rs1799987) with risk and progression toward CCC. We performed a cross-sectional association study of 406 seropositive patients from endemic areas for CD in the State of Pernambuco, Northeast Brazil. The patients were classified as non-cardiopathic (A, n = 110) or cardiopathic (mild, B1, n = 163; severe, C, n = 133). Serum levels of CCL5 and CCL2/MCP-1 were elevated in CD patients but were neither associated with risk/severity of CCC nor with SNP genotypes. After logistic regression analysis with adjustment for the covariates gender and ethnicity, CCL5 -403 (rs2107538) CT heterozygotes (OR = 0.5, P-value = 0.04) and T carriers (OR = 0.5, P-value = 0.01) were associated with protection against CCC. To gain insight into the participation of the CCL5-CCR5/CCR1 axis in CCC, mice were infected with the Colombian T. cruzi strain. Increased CCL5 concentrations were detected in cardiac tissue. In spleen, frequencies of CCR1⁺ CD8⁺ T cells and CD14⁺ macrophages were decreased, while frequencies of CCR5⁺ cells were increased. Importantly, CCR1⁺CD14⁺ macrophages were mainly IL-10⁺, while CCR5⁺ cells were mostly TNF⁺. CCR5-deficient infected mice presented reduced TNF concentrations and injury in heart tissue. Selective blockade of CCR1 (Met-RANTES therapy) in infected Ccr5^-/- mice supported a protective role for CCR1 in CCC. Furthermore, parasite antigen stimulation of CD patient blood cells increased the frequency of CCR1⁺CD8⁺ T cells and CCL5 production. Collectively, our data support that a genetic variant of CCL5 and CCR1⁺ cells confer protection against Chagas heart disease, identifying the CCL5-CCR1 axis as a target for immunostimulation.

Association of caspase-1 polymorphisms with Chagas cardiomyopathy among individuals in Santa Cruz, Bolivia

INTRODUCTION:

Trypanosoma cruzi (Tc) infection is usually acquired in childhood in endemic areas, leading to Chagas disease, which progresses to Chagas cardiomyopathy in 20-30% of infected individuals over decades. The pathogenesis of Chagas cardiomyopathy involves the host inflammatory response to T. cruzi, in which upstream caspase-1 activation prompts the cascade of inflammatory chemokines/cytokines, cardiac remodeling, and myocardial dysfunction. The aim of the present study was to examine the association of two caspase-1 single nucleotide polymorphisms (SNPs) with cardiomyopathy.

METHODS:

We recruited infected (Tc+, n = 149) and uninfected (Tc-, n = 87) participants in a hospital in Santa Cruz, Bolivia. Cardiac status was classified (I, II, III, IV) based on Chagas cardiomyopathy-associated electrocardiogram findings and ejection fractions on echocardiogram. Genotypes were determined using Taqman probes via reverse transcription-polymerase chain reaction of peripheral blood DNA. Genotype frequencies were analyzed according to three inheritance patterns (dominant, recessive, additive) using logistic regression adjusted for age and sex.

RESULTS:

The AA allele for the caspase-1 SNP rs501192 was more frequent in Tc+ cardiomyopathy (classes II, III, IV) patients compared to those with a normal cardiac status (class I) [odds ratio (OR) = -2.18, p = 0.117]. This trend approached statistical significant considering only Tc+ patients in class I and II (OR = -2.64, p = 0.064).

CONCLUSIONS:

Caspase-1 polymorphisms may play a role in Chagas cardiomyopathy development and could serve as markers to identify individuals at higher risk for priority treatment.

Plasma concentrations of CCL3 and CCL4 in the cardiac and digestive clinical forms of chronic Chagas disease

The aim of this study was to investigate the plasma levels of the CCL3 and CCL4 chemokines in patients with the cardiac and digestive clinical forms of chronic Chagas disease and in cardiac patients with and without left ventricular systolic dysfunction (LVSD). Plasma samples from 75 patients were evaluated by enzyme-linked immunosorbent assay (ELISA) to confirm infection by T. cruzi. Plasma levels of the CCL3 and CCL4 chemokines were measured using Milliplex® MAP assay (Millipore). There were no significant differences in the levels of CCL3 and CCL4 between patients with the digestive and cardiac clinical forms of Chagas disease. Moreover, no significant differences were found between patients without LVSD and those with LVSD. Higher CCL3 and CCL4 plasma levels were found in patients with LVSD compared to those with the digestive form of the disease. The CCL3 and CCL4 chemokines might not be involved in differential susceptibility to the digestive and cardiac clinical forms of chronic Chagas disease, and it seems they do not influence the development of LVSD.

Doxycycline and Benznidazole Reduce the Profile of Th1, Th2, and Th17 Chemokines and Chemokine Receptors in Cardiac Tissue from Chronic Trypanosoma cruzi-Infected Dogs

Chemokines (CKs) and chemokine receptors (CKR) promote leukocyte recruitment into cardiac tissue infected by the Trypanosoma cruzi. This study investigated the long-term treatment with subantimicrobial doses of doxycycline (Dox) in association, or not, with benznidazole (Bz) on the expression of CK and CKR in cardiac tissue. Thirty mongrel dogs were infected, or not, with the Berenice-78 strain of T. cruzi and grouped according their treatments: (i) two months after infection, Dox (50 mg/kg) 2x/day for 12 months; (ii) nine months after infection, Bz (3,5 mg/kg) 2x/day for 60 days; (iii) Dox + Bz; and (iv) vehicle. After 14 months of infection, hearts were excised and processed for qPCR analysis of Th1 (CCL2, CCL3, CCL4, CCL5, CXCL9, and CXCL11), Th2 (CCL1, CCL17, CCL24, and CCL26), Th17 (CCL20) CKs, Th1 (CCR5, CCR6, and CXCR3), and Th2/Th17 (CCR3, CCR4, and CCR8) CKR, as well as IL-17. T. cruzi infection increases CCL1, CCL2, CCL4, CCL5, CCL17, CXCL10, and CCR5 expression in the heart. Dox, Bz, or Dox + Bz treatments cause a reversal of CK and CKR and reduce the expression of CCL20, IL-17, CCR6, and CXCR3. Our data reveal an immune modulatory effect of Dox with Bz, during the chronic phase of infection suggesting a promising therapy for cardiac protection.

The role of CCR5 in Chagas disease - a systematic review

Chagas disease is an infection caused by the protozoan Trypanosoma cruzi. The clinical manifestations result from the chronic forms of the disease: indeterminate, cardiac, digestive or mixed. The pathogenesis of this disease is related to the genetic variability of both the parasite and the host with polymorphisms of genes involved in immune response possibly being involved in the variable clinical course. Cytokines play a key role in regulating immune response, in particular chemokines exert a crucial role in the control of leukocyte migration during the host's response to infectious processes. Furthermore, inflammatory cytokines and chemokines have been implicated in the generation of inflammatory infiltrates and tissue damage. The involvement of the CC Chemokine Receptor 5 (CCR5) in leukocyte migration to sites of inflammation has been elucidated and this receptor has been investigated in Chagas disease. Here we review the role of CCR5 in T. cruzi infection as well as its importance in the pathogenesis of the Chagas disease.

Impact of genetic variations in C-C chemokine receptors and ligands on infectious diseases

Chemokine receptors and ligands are crucial for extensive immune response against infectious diseases such as malaria, leishmaniasis, HIV and tuberculosis and a wide variety of other diseases. Role of chemokines are evidenced in the activation and regulation of immune cell migration which is important for immune response against diseases. Outcome of disease is determined by complex interaction among pathogen, host genetic variability and surrounding milieu. Variation in expression or function of chemokines caused by genetic polymorphisms could be associated with attenuated immune responses. Exploration of chemokine genetic polymorphisms in therapeutic response, gene regulation and disease outcome is important. Infectious agents in human host alter the expression of chemokines via epigenetic alterations and thus contribute to disease pathogenesis. Although some fragmentary data are available on chemokine genetic variations and their contribution in diseases, no unequivocal conclusion has been arrived as yet. We therefore, aim to investigate the association of CCR5-CCL5 and CCR2-CCL2 genetic polymorphisms with different infectious diseases, transcriptional regulation of gene, disease severity and response to therapy. Furthermore, the role of epigenetics in genes related to chemokines and infectious disease are also discussed.

Chemokines and Heart Disease: A Network Connecting Cardiovascular Biology to Immune and Autonomic Nervous Systems

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.

IL18 Gene Variants Influence the Susceptibility to Chagas Disease

Chagas disease is a parasitic disorder caused by the infection with the flagellated protozoan Trypanosoma cruzi. According to the World Health Organization, more than six million people are currently infected in endemic regions. Genetic factors have been proposed to influence predisposition to infection and development of severe clinical phenotypes like chronic Chagas cardiomyopathy (CCC). Interleukin 18 (IL18) encodes a proinflammatory cytokine that has been proposed to be involved in controlling T. cruzi infection. In this study, we analyzed the possible role of six IL18 gene variants (rs5744258, rs360722, rs2043055, rs187238, rs1946518 and rs360719), which cover most of the variation within the locus, in the susceptibility to infection by T. cruzi and/or CCC. In total, 1,171 individuals from a Colombian region endemic for Chagas disease, classified as seronegative (n = 595), seropositive asymptomatic (n = 175) and CCC (n = 401), were genotyped using TaqMan probes. Significant associations with T. cruzi infection were observed when comparing seronegative and seropositive individuals for rs187238 (P = 2.18E-03, OR = 0.77), rs360719 (P = 1.49E-03, OR = 0.76), rs2043055 (P = 2.52E-03, OR = 1.29), and rs1946518 (P = 0.0162, OR = 1.22). However, dependence analyses suggested that the association was mainly driven by the polymorphism rs360719. This variant is located within the promoter region of the IL18 gene, and it has been described that it creates a binding site for the transcription factor OCT-1 affecting IL-18 expression levels. In addition, no evidence of association was observed between any of the analyzed IL18 gene polymorphisms and the development of CCC. In summary, our data suggest that genetic variation within the promoter region of IL18 is directly involved in the susceptibility to infection by T. cruzi, which provides novel insight into disease pathophysiology and adds new perspectives to achieve a more effective disease control.

Genetic Susceptibility to Cardiac and Digestive Clinical Forms of Chronic Chagas Disease: Involvement of the CCR5 59029 A/G Polymorphism

The clinical manifestations of chronic Chagas disease include the cardiac form of the disease and the digestive form. Not all the factors that act in the variable clinical course of this disease are known. This study investigated whether the CCR5Δ32 (rs333) and CCR5 59029 A/G (promoter region--rs1799987) polymorphisms of the CCR5 gene are associated with different clinical forms of chronic Chagas disease and with the severity of left ventricular systolic dysfunction in patients with chronic Chagas heart disease (CCHD). The antibodies anti-T. cruzi were identified by ELISA. PCR and PCR-RFLP were used to identify the CCR5Δ32 and CCR5 59029 A/G polymorphisms. The chi-square test was used to compare variables between groups. There was a higher frequency of the AA genotype in patients with CCHD compared with patients with the digestive form of the disease and the control group. The results also showed a high frequency of the AG genotype in patients with the digestive form of the disease compared to the other groups. The results of this study show that the CCR5Δ32 polymorphism does not seem to influence the different clinical manifestations of Chagas disease but there is involvement of the CCR5 59029 A/G polymorphism in susceptibility to the different forms of chronic Chagas disease. Besides, these polymorphisms do not influence left ventricular systolic dysfunction in patients with CCHD.

Investigation of the role of IL17A gene variants in Chagas disease

Human host genetic factors have been suggested to be determinants of the prevalence and clinical forms of Chagas disease. In this regard, IL-17A is believed to control parasitemia and protect against heart disease. In this work, we assessed whether IL17A gene polymorphisms are related to infection and/or development of the cardiac form of Chagas disease by genotyping for five IL17A SNPs (rs4711998, rs8193036, rs3819024, rs2275913 and rs7747909) in 1171 individuals from a Colombian region endemic for Chagas disease, classified as seronegative (n=595), seropositive asymptomatic (n=175) and chronic Chagas cardiomyopathy (n=401). Our results showed that SNP rs8193036, which is located upstream of the coding region of the gene, was slightly associated with protection against T. cruzi infection (P=0.0170, P(FDR)=0.0851, odds ratio (OR)=0.80, confidence interval (CI)=0.66-0.96) and associated with protection against the development of cardiomyopathy (P=0.0065, P(FDR)=0.0324, OR=0.75, CI=0.60-0.92). This finding suggests that this IL17A polymorphism could be associated with Trypanosoma cruzi infection and the development of chronic cardiomyopathy due to differential expression of cytokine IL-17A.

Human leucocyte antigen-G (HLA-G) and its murine functional homolog Qa2 in the Trypanosoma cruzi Infection

Genetic susceptibility factors, parasite strain, and an adequate modulation of the immune system seem to be crucial for disease progression after Trypanosoma cruzi infection. HLA-G and its murine functional homolog Qa2 have well-recognized immunomodulatory properties. We evaluated the HLA-G 3′ untranslated region (3′UTR) polymorphic sites (associated with mRNA stability and target for microRNA binding) and HLA-G tissue expression (heart, colon, and esophagus) in patients presenting Chagas disease, stratified according to the major clinical variants. Further, we investigated the transcriptional levels of Qa2 and other pro- and anti-inflammatory genes in affected mouse tissues during T. cruzi experimental acute and early chronic infection induced by the CL strain. Chagas disease patients exhibited differential HLA-G 3′UTR susceptibility allele/genotype/haplotype patterns, according to the major clinical variant (digestive/cardiac/mixed/indeterminate). HLA-G constitutive expression on cardiac muscle and colonic cells was decreased in Chagasic tissues; however, no difference was observed for Chagasic and non-Chagasic esophagus tissues. The transcriptional levels of Qa2 and other anti and proinflammatory (CTLA-4, PDCD1, IL-10, INF-γ, and NOS-2) genes were induced only during the acute T. cruzi infection in BALB/c and C57BL/6 mice. We present several lines of evidence indicating the role of immunomodulatory genes and molecules in human and experimental T. cruzi infection.

Trypanosoma cruzi strains cause different myocarditis patterns in infected mice

AIMS

Chagas disease pathology is dependent on the infecting Trypanosoma cruzi strain. However, the relationship between the extent and type of myocarditis caused by different T. cruzi strains in the acute and chronic phases of infection has not been studied in detail. To address this, we infected mice with three genetically distant T. cruzi strains as well as infected in vitro different cell types.

METHODS AND RESULTS

Parasitemia was detected in mice infected with the Y and VFRA strains, but not with the Sc43 strain; however, only the Y strain was lethal. When infected with VFRA, mice showed higher inflammation and parasitism in the heart than with Sc43 strain. Y and VFRA caused homogeneous pancarditis with inflammatory infiltrates along the epicardium, whereas Sc43 caused inflammation preferentially in the auricles in association with intracellular parasite localization. We observed intramyocardic perivasculitis in mice infected with the VFRA and Y strains, but not with Sc43, during the acute phase, which suggests that endothelial cells may be involved in heart colonization by these more virulent strains. In in vitro infection assays, the Y strain had the highest parasite-cell ratio in epithelial, macrophage and endothelial cell lines, but Y and VFRA strains were higher than Sc43 in cardiomyocytes.

CONCLUSIONS

This study supports parasite variability as a cause for the diverse cardiac outcomes observed in Chagas disease, and suggests that endothelial cells could be involved in heart infection during the acute phase.

Genetic susceptibility to Chagas disease cardiomyopathy: involvement of several genes of the innate immunity and chemokine-dependent migration pathways

BACKGROUND

Chagas disease, caused by the protozoan Trypanosoma cruzi is endemic in Latin America. Thirty percent of infected individuals develop chronic Chagas cardiomyopathy (CCC), an inflammatory dilated cardiomyopathy that is, by far, the most important clinical consequence of T. cruzi infection. The others remain asymptomatic (ASY). A possible genetic component to disease progression was suggested by familial aggregation of cases and the association of markers of innate and adaptive immunity genes with CCC development. Migration of Th1-type T cells play a major role in myocardial damage.

METHODS

Our genetic analysis focused on CCR5, CCL2 and MAL/TIRAP genes. We used the Tag SNPs based approach, defined to catch all the genetic information from each gene. The study was conducted on a large Brazilian population including 315 CCC cases and 118 ASY subjects.

RESULTS

The CCL2rs2530797A/A and TIRAPrs8177376A/A were associated to an increase susceptibility whereas the CCR5rs3176763C/C genotype is associated to protection to CCC. These associations were confirmed when we restricted the analysis to severe CCC, characterized by a left ventricular ejection fraction under 40%.

CONCLUSIONS

Our data show that polymorphisms affecting key molecules involved in several immune parameters (innate immunity signal transduction and T cell/monocyte migration) play a role in genetic susceptibility to CCC development. This also points out to the multigenic character of CCC, each polymorphism imparting a small contribution. The identification of genetic markers for CCC will provide information for pathogenesis as well as therapeutic targets.

Genetic susceptibility to Chagas disease: an overview about the infection and about the association between disease and the immune response genes

Chagas disease, which is caused by the flagellate parasite Trypanosoma cruzi, affects 8-10 million people in Latin America. The disease is endemic and is characterised by acute and chronic phases that develop in the indeterminate, cardiac, and/or gastrointestinal forms. The immune response during human T. cruzi infection is not completely understood, despite its role in driving the development of distinct clinical manifestations of chronic infection. Polymorphisms in genes involved in the innate and specific immune response are being widely studied in order to clarify their possible role in the occurrence or severity of disease. Here we review the role of classic and nonclassic MHC, KIR, and cytokine host genetic factors on the infection by T. cruzi and the clinical course of Chagas disease.

Chagas disease: an overview of clinical and epidemiological aspects

Chagas disease, caused by the parasite Trypanosoma cruzi, is a serious health problem in Latin America and is an emerging disease in non-endemic countries. In recent decades, the epidemiological profile of the disease has changed due to new patterns of immigration and successful control in its transmission, leading to the urbanization and globalization of the disease. Dilated cardiomyopathy is the most important and severe manifestation of human chronic Chagas disease and is characterized by heart failure, ventricular arrhythmias, heart blocks, thromboembolic phenomena, and sudden death. This article will present an overview of the clinical and epidemiological aspects of Chagas disease. It will focus on several clinical aspects of the disease, such as chronic Chagas disease without detectable cardiac pathology, as well as dysautonomia, some specific features, and the principles of treatment of chronic cardiomyopathy.

Myocardial chemokine expression and intensity of myocarditis in Chagas cardiomyopathy are controlled by polymorphisms in CXCL9 and CXCL10

Background

Chronic Chagas cardiomyopathy (CCC), a life-threatening inflammatory dilated cardiomyopathy, affects 30% of the approximately 8 million patients infected by Trypanosoma cruzi. Even though the Th1 T cell-rich myocarditis plays a pivotal role in CCC pathogenesis, little is known about the factors controlling inflammatory cell migration to CCC myocardium.

Methods and Results

Using confocal immunofluorescence and quantitative PCR, we studied cell surface staining and gene expression of the CXCR3, CCR4, CCR5, CCR7, CCR8 receptors and their chemokine ligands in myocardial samples from end-stage CCC patients. CCR5+, CXCR3+, CCR4+, CCL5+ and CXCL9+ mononuclear cells were observed in CCC myocardium. mRNA expression of the chemokines CCL5, CXCL9, CXCL10, CCL17, CCL19 and their receptors was upregulated in CCC myocardium. CXCL9 mRNA expression directly correlated with the intensity of myocarditis, as well as with mRNA expression of CXCR3, CCR4, CCR5, CCR7, CCR8 and their ligands. We also analyzed single-nucleotide polymorphisms for genes encoding the most highly expressed chemokines and receptors in a cohort of Chagas disease patients. CCC patients with ventricular dysfunction displayed reduced genotypic frequencies of CXCL9 rs10336 CC, CXCL10 rs3921 GG, and increased CCR5 rs1799988CC as compared to those without dysfunction. Significantly, myocardial samples from CCC patients carrying the CXCL9/CXCL10 genotypes associated to a lower risk displayed a 2–6 fold reduction in mRNA expression of CXCL9, CXCL10, and other chemokines and receptors, along with reduced intensity of myocarditis, as compared to those with other CXCL9/CXCL10 genotypes.

Conclusions

Results may indicate that genotypes associated to reduced risk in closely linked CXCL9 and CXCL10 genes may modulate local expression of the chemokines themselves, and simultaneously affect myocardial expression of other key chemokines as well as intensity of myocarditis. Taken together our results may suggest that CXCL9 and CXCL10 are master regulators of myocardial inflammatory cell migration, perhaps affecting clinical progression to the life-threatening form of CCC.

Chronic Chagas cardiomyopathy (CCC) is an inflammatory heart disease that affects millions in Latin America, and in growing numbers in USA and Europe. Survival among CCC patients is shorter than among patients with cardiomyopathy of non-inflammatory etiology. This suggests that the inflammatory cell influx plays an important pathogenic role in CCC. However, little is known about the factors that maintain this myocardial inflammation. We hypothesized that Th1 T cell-attracting chemokines, involved in driving leukocyte migration, could play a role in myocardial inflammation. Herein, we have analyzed expression of several chemokines and receptors in heart tissue from patients with CCC and controls. We found inflammatory cells expressing chemokines and receptors consistent with Th1 T cell influx into CCC myocardium. mRNA expression levels of the chemokine CXCL9 correlated with inflammation. We also studied whether genetic variations in these genes could be associated to CCC development. Polymorphisms in CXCL9, CXCL10 and CCR5 were associated to differential risk of progression to the more severe form of CCC. Polymorphisms of CXCL9 and CXCL10 were also associated to the intensity of myocardial inflammation and chemokine expression. These results suggest that such chemokines may be master regulators of myocardial inflammatory cell migration, perhaps affecting clinical progression to severe CCC.