Association of the macrophage migration inhibitory factor -173G/C polymorphism with Chagas 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.

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.

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.

Association between Macrophage Migration Inhibitory Factor Gene Variation and Response to Glucocorticoid Treatment in Sudden Sensorineural Hearing Loss

Several lines of evidence suggest the role of the immune system in the pathogenesis of sudden sensorineural hearing loss (SSNHL). Macrophage migration inhibitory factor (MIF) mediates its role in various immune and inflammatory conditions by the regulation of immune reactions. Several studies have confirmed an association between MIF gene polymorphisms and susceptibility to various inflammatory and autoimmune disorders. The aim of this study was to explore the association between the MIF (-173 G/C) polymorphism (rs755622) and SSNHL in an Iranian population. In this case-control association study, SSNHL cases (n = 77) were included. Normal healthy subjects (n = 100) were also recruited from the same region. Genotyping for MIF (-173 G/C) polymorphism was carried out using the polymerase chain reaction-restriction fragment length polymorphism technique. The frequency of the MIF -173 C allele carriers (GC + CC genotype) was significantly elevated in SSNHL patients who responded to glucocorticoid treatment compared with the patients with no response to treatment. These results suggest that the MIF gene polymorphism is associated with a response to glucocorticoid treatment in patients with SSNHL.

Chagas disease cardiomyopathy: immunopathology and genetics

Chagas disease, caused by the protozoan Trypanosoma cruzi, is endemic in Latin America and affects ca. 10 million people worldwide. About 30% of Chagas disease patients develop chronic Chagas disease cardiomyopathy (CCC), a particularly lethal inflammatory cardiomyopathy that occurs decades after the initial infection, while most patients remain asymptomatic. Mortality rate is higher than that of noninflammatory cardiomyopathy. CCC heart lesions present a Th1 T-cell-rich myocarditis, with cardiomyocyte hypertrophy and prominent fibrosis. Data suggest that the myocarditis plays a major pathogenetic role in disease progression. Major unmet goals include the thorough understanding of disease pathogenesis and therapeutic targets and identification of prognostic genetic factors. Chagas disease thus remains a neglected disease, with no vaccines or antiparasitic drugs proven efficient in chronically infected adults, when most patients are diagnosed. Both familial aggregation of CCC cases and the fact that only 30% of infected patients develop CCC suggest there might be a genetic component to disease susceptibility. Moreover, previous case-control studies have identified some genes associated to human susceptibility to CCC. In this paper, we will review the immunopathogenesis and genetics of Chagas disease, highlighting studies that shed light on the differential progression of Chagas disease patients to CCC.

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.

Relationship between MIF-173 G/C polymorphism and susceptibility to chronic hepatitis B and HBV-induced liver cirrhosis

Macrophage migration inhibitory factor (MIF), a pro-inflammatory cytokine, played an important role in immune-mediated diseases. The promoter region of MIF, which had functional polymorphisms, controlled MIF expression. MIF polymorphism was associated with many inflammatory diseases. But the association of MIF polymorphism with chronic hepatitis B (CHB) or HBV-induced liver cirrhosis (HC) had not yet been reported. In present study, polymorphism of MIF-173 was genotyped in 95 CHB patients, 73 HC patients and 90 healthy controls in southern China. The frequency of MIF-173 C/C genotype in patients with CHB or HC was statistically significantly higher than that in healthy controls, respectively. Moreover, difference in the distribution of MIF-173 C allele between CHB patients and healthy controls was statistically significant. However, there was no statistical relationship between MIF-173 genotype and clinical features in patients with CHB or HC. Our results suggest that MIF-173 C/C polymorphism might be associated with increased risk of CHB or HC in Chinese southern population.

Pathogenesis of Chagas disease cardiomyopathy

Chagas disease, or American trypanosomiasis, is a parasitic infection caused by the flagellate protozoan Trypanosoma cruzi. Chagas disease is mainly affecting rural populations in Mexico and Central and South America. The World Health Organization estimates that 300 000 new cases of Chagas disease occur every year and approximately 20 000 deaths are attributable to Chagas. However, this organisation classified Chagas disease as a neglected tropical disease. The economic burden of this disease is significant. In many Latin American countries, the direct and indirect costs, including the cost of health care in dollars and loss of productivity, attributable to Chagas disease ranges from $40 million to in excess of $800 million per nation per annum. So, it remains a contemporary public health concern. In chronic phase, mortality is primarily due to the rhythm disturbances and congestive heart failure that result from the chronic inflammatory cardiomyopathy (CCC) due to the persistence presence of parasites in the heart tissue. Mechanisms underlying differential progression to CCC are still incompletely understood. In the last decades immunological proteomic genetic approaches lead to significant results which help to disperse the veil covering the knowledge of the pathogenic process. Here, we reported these significant progresses.

Genetic susceptibility to chronic Chagas disease: an overview of single nucleotide polymorphisms of cytokine genes

Chagas disease is a parasitic infection that is a significant public health problem in Latin America. The mechanisms responsible for susceptibility to the infection and the mechanisms involved in the development of cardiac and digestive forms of chronic Chagas disease remain poorly understood. However, there is growing evidence that differences in susceptibility in endemic areas may be attributable to host genetic factors. The aim of this overview was to analyze the genetic susceptibility to human Chagas disease, particularly that of single nucleotide polymorphisms of cytokine genes. A review of the literature was conducted on the following databases: PubMed/MEDLINE and Scopus. The search strategy included using the following terms: "Cytokines", "Single Nucleotide Polymorphisms" and "Chagas Disease". After screening 25 citations from the databases, 19 studies were selected for the overview. A critical analysis of the data presented in the articles suggests that genetic susceptibility to Chagas disease and chronic Chagas cardiomyopathy is highly influenced by the complexity of the immune response of the host. Follow-up studies based on other populations where Chagas disease is endemic (with distinct ethnic and genetic backgrounds) need to be conducted. These should use a large sample population so as to establish what cytokine genes are involved in susceptibility to and/or progression of the disease.

Macrophage migration inhibitory factor in protozoan infections

Macrophage migration inhibitory factor (MIF) is a cytokine that plays a central role in immune and inflammatory responses. In the present paper, we discussed the participation of MIF in the immune response to protozoan parasite infections. As a general trend, MIF participates in the control of parasite burden at the expense of promoting tissue damage due to increased inflammation.

Interleukin 4, interleukin 4 receptor-α and interleukin 10 gene polymorphisms in Chagas disease

In this study, we investigated the association between single-nucleotide polymorphisms (SNPs) of the interleukin-4 (IL4), interleukin-4 receptor-α (IL4RA) and interleukin-10 (IL10) genes with the development of chagasic heart disease. This study included 260 patients from Colombia who were serologically positive for Trypanosoma cruzi antigens (cardiomyopathic, n=130; asymptomatic, n=130). Genotypes were determined by polymerase chain reaction (PCR)-restriction fragment length polymorphism or sequence-specific primer methods. We found statistically significant differences in the distribution of the IL4RA +148 AA (P=0·025, OR=1·89, CI=1·04-3·43) genotype when comparing asymptomatic and symptomatic patients. No statistically significant differences in the genotype and allele frequency of IL4 and IL10 gene polymorphisms between symptomatic and asymptomatic patients were observed. Our experimental evidence suggests that the IL4RA +148 AA genotype has a weak association with the development of chagasic cardiomyopathy in the population under study.

Role of the IFNG +874T/A polymorphism in Chagas disease in a Colombian population

Genetic susceptibility to Trypanosoma cruzi infection and the development of cardiomyopathy is complex, heterogeneous, and likely involves several genes. Previous studies have implicated cytokine and chemokine genes in susceptibility to Chagas disease. Here we investigated the association between the interferon-gamma gene (IFNG) +874T/A polymorphism and Chagas disease, focusing on susceptibility and severity. This study included 236 chagasic patients (asymptomatic, n=116; cardiomyopathic, n=120) and 282 healthy controls from a Colombian population where T. cruzi is highly endemic. Individuals were genotyped for functional single nucleotide polymorphism (SNP; rs2430561; A/T) of the IFNG gene by amplification refractory mutational system PCR (ARMS-PCR). Moreover, clinical manifestations of Chagas in patients were analyzed. We found a significant difference in the distribution of the IFNG +874 "A" allele between patients and healthy controls (P=0.003; OR=1.46, 95% CI, 1.13-1.89). The frequency of the IFNG +874 genotype A/A, which is associated with reduced production of interferon-gamma, was increased in the patients relative to controls (38.1% vs. 26.6%). We compared the frequencies of IFNG alleles and genotypes between asymptomatic patients and those with chagasic cardiomyopathy and found no significant difference. Our data suggest that the IFNG +874T/A genetic polymorphism may be involved in susceptibility but not in the progression of Chagas disease in this Colombian population.

Lack of association between IL-6-174G/C gene polymorphism and Chagas disease

The aim of this study was to investigate the role of the IL-6-174G/C gene polymorphism in susceptibility/resistance to Trypanosoma cruzi infection in two independent cohorts from Colombia and Peru. We determined the IL-6-174G/C genotypes in a sample of 399 seronegative individuals and 317 serologically positive patients from Colombia and Peru. All individuals are from regions where T. cruzi infection is endemic. No statistically significant differences in the frequency of IL-6-174G/C gene polymorphism between chagasic patients and controls or between asymptomatic and individuals with cardiomyopathy were observed. Our results do not support an evidence for a major role contribution of this IL-6 gene polymorphism in the susceptibility to or clinical manifestations of Chagas disease in these studied cohorts.