Christophe Chevillard

Analysis of the 5q31-q33 Locus Shows an Association between IL13-1055C/T IL-13-591A/G Polymorphisms and Schistosoma haematobium Infections

Millions of humans are exposed to schistosome infections, which cause severe kidney and liver disease and 280,000 deaths annually. Th2-mediated immunity is critical to human defenses against this pathogen and susceptibility to infection is controlled by a major genetic locus that includes IL4, IL5, and IL13 genes. These observations led us to evaluate whether certain polymorphisms in IL4, IL5, or IL13 determine schistosome infection. The study was performed in two Dogon villages where Schistosoma haematobium is endemic. Schistosome infections were evaluated by counting eggs and measuring worm Ags in urine. Genetic polymorphisms were determined by restriction enzyme analysis or by primer extension and denaturing high-performance liquid chromatography analysis. Associations were tested using family-based association tests and logistical regression analysis. The alleles IL13-1055C (p = 0.05) and IL13-591A (p = 0.01) are shown, by family-based association test, to be preferentially transmitted to children with the 10% highest infections. A logistic regression analysis that included IL13-1055 G/G, G/T and T/T genotypes, age, gender, and village of residency, applied to the whole study population, showed that subjects bearing the IL13-1055T/T genotype were on average much less infected than individuals with other genotypes. Previous studies on asthma indicated that the IL13-1055T allele increased gene transcription, which is in agreement with the fact that this cytokine enhances resistance to infection by schistosome in humans.

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.

MicroRNAs miR-1, miR-133a, miR-133b, miR-208a and miR-208b are dysregulated in Chronic Chagas disease Cardiomyopathy

BACKGROUND/METHODS Chagas disease is caused by an intracellular parasite, Trypanosoma cruzi, and it is a leading cause of heart failure in Latin America. The main clinical consequence of the infection is the development of a Chronic Chagas disease Cardiomyopathy (CCC), which is characterized by myocarditis, hypertrophy and fibrosis and affects about 30% of infected patients. CCC has a worse prognosis than other cardiomyopathies, like idiopathic dilated cardiomyopathy (DCM). It is well established that myocardial gene expression patterns are altered in CCC, but the molecular mechanisms underlying these differences are not clear. MicroRNAs are recently discovered regulators of gene expression, and are recognized as important factors in heart development and cardiovascular disorders (CD). We analyzed the expression of nine different miRNAs in myocardial tissue samples of CCC patients in comparison to DCM patients and samples from heart transplant donors. Using the results of a cDNA microarray database on CCC and DCM myocardium, signaling networks were built and nodal molecules were identified. RESULTS We observed that five miRNAs were significantly altered in CCC and three in DCM; importantly, three miRNAs were significantly reduced in CCC as compared to DCM. We observed that multiple gene targets of the differentially expressed miRNAs showed a concordant inverse expression in CCC. Significantly, most gene targets and involved networks belong to crucial disease-related signaling pathways. CONCLUSION These results suggest that miRNAs may play a major role in the regulation of gene expression in CCC pathogenesis, with potential implication as diagnostic and prognostic tools.

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

BackgroundChagas 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.MethodsOur 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.ResultsThe 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%.ConclusionsOur 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.

Polymorphism in the Alpha Cardiac Muscle Actin 1 Gene Is Associated to Susceptibility to Chronic Inflammatory Cardiomyopathy

Aims Chagas disease, caused by the protozoan Trypanosoma cruzi is endemic in Latin America, and may lead to a life-threatening inflammatory dilated, chronic Chagas cardiomyopathy (CCC). One third of T. cruzi-infected individuals progress to CCC while 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. Since mutations in multiple sarcomeric genes, including alpha-cardiac actin (ACTC1) have been involved in hereditary dilated cardiomyopathy, we investigated the involvement of the ACTC1 gene in CCC pathogenesis. Methods and Results We conducted a proteomic and genetic study on a Brazilian study population. The genetic study was done on a main cohort including 118 seropositive asymptomatic subjects and 315 cases and the replication was done on 36 asymptomatic and 102 CCC cases. ACTC1 protein and mRNA levels were lower in myocardial tissue from patients with end-stage CCC than those found in hearts from organ donors. Genotyping a case-control cohort of CCC and ASY subjects for all informative single nucleotide polymorphism (SNP) in the ACTC1 gene identified rs640249 SNP, located at the 5’ region, as associated to CCC. Associations are borderline after correction for multiple testing. Correlation and haplotype analysis led to the identification of a susceptibility haplotype. Functional assays have shown that the rs640249A/C polymorphism affects the binding of transcriptional factors in the promoter regions of the ACTC1 gene. Confirmation of the detected association on a larger independent replication cohort will be useful. Conclusions Genetic variations at the ACTC1 gene may contribute to progression to chronic Chagas Cardiomyopathy among T. cruzi-infected patients, possibly by modulating transcription factor binding to ACTC1 promoter regions.

Interferon-γ and other inflammatory mediators in cardiomyocyte signaling during Chagas disease cardiomyopathy.

Chagas disease cardiomyopathy (CCC), the main consequence of Trypanosoma cruzi (T.cruzi) infection, is an inflammatory cardiomyopathy that develops in up to 30% of infected individuals. The heart inflammation in CCC patients is characterized by a Th1 T cell-rich myocarditis with increased production of interferon (IFN)-γ, produced by the CCC myocardial infiltrate and detected at high levels in the periphery. IFN-γ has a central role in the cardiomyocyte signaling during both acute and chronic phases of T.cruzi infection. In this review, we have chosen to focus in its pleiotropic mode of action during CCC, which may ultimately be the strongest driver towards pathological remodeling and heart failure. We describe here the antiparasitic protective and pathogenic dual role of IFN-γ in Chagas disease.

Functional IL18 polymorphism and susceptibility to Chronic Chagas Disease

BACKGROUND Chronic Chagas Disease cardiomyopathy (CCC), a life-threatening inflammatory dilated cardiomyopathy, affects 30% of the approximately 8 million patients infected by Trypanosoma cruzi, the rest of the infected subjects remaining asymptomatic (ASY). The Th1 T cell-rich myocarditis plays a pivotal role in CCC pathogenesis. Local expression of IL-18 in CCC myocardial tissue has recently been described. IL-18 could potentially amplify the process by inducing increased expression of IFN-γ which in turn can increase the production of IL-18, thereby creating a positive feedback mechanism. In order to assess the contribution of the IL-18 to susceptibility to Chronic Chagas Disease, we investigated the association between a single nucleotide polymorphism (SNP) located in the IL-18 gene with the risk of developing Chagas cardiomyopathy. METHODS AND RESULTS We analyzed the rs2043055 marker in the IL18 gene in a cohort of Chagas disease cardiomyopathy patients (n=849) and asymptomatic subjects (n=202). We found a significant difference in genotype frequencies among moderate and severe CCC patients with ventricular dysfunction. CONCLUSIONS Our analysis suggests that the IL18 rs2043055 polymorphism- or a SNP in tight linkage disequilibrium with it- may contribute to modulating the Chagas cardiomyopathy outcome.

Myocardial Infarction–Associated Transcript, a Long Noncoding RNA, Is Overexpressed During Dilated Cardiomyopathy Due to Chronic Chagas Disease

Long noncoding RNAs (lncRNAs) modulate gene expression at the epigenetic, transcriptional, and posttranscriptional levels. Dysregulation of the lncRNA known as myocardial infarction-associated transcript (MIAT) has been associated with myocardial infarction. Chagas disease causes a severe inflammatory dilated chronic cardiomyopathy (CCC). We investigated the role of MIAT in CCC. A whole-transcriptome analysis of heart biopsy specimens and formalin-fixed, paraffin-embedded samples revealed that MIAT was overexpressed in patients with CCC, compared with subjects with noninflammatory dilated cardiomyopathy and controls. These results were confirmed in a mouse model. Results suggest that MIAT is a specific biomarker of CCC.

MicroRNA Transcriptome Profiling in Heart of Trypanosoma cruzi-Infected Mice: Parasitological and Cardiological Outcomes

Chagas disease is caused by the parasite Trypanosoma cruzi, and it begins with a short acute phase characterized by high parasitemia followed by a life-long chronic phase with scarce parasitism. Cardiac involvement is the most prominent manifestation, as 30% of infected subjects will develop abnormal ventricular repolarization with myocarditis, fibrosis and cardiomyocyte hypertrophy by undefined mechanisms. Nevertheless, follow-up studies in chagasic patients, as well as studies with murine models, suggest that the intensity of clinical symptoms and pathophysiological events that occur during the acute phase of disease are associated with the severity of cardiac disease observed during the chronic phase. In the present study we investigated the role of microRNAs (miRNAs) in the disease progression in response to T. cruzi infection, as alterations in miRNA levels are known to be associated with many cardiovascular disorders. We screened 641 rodent miRNAs in heart samples of mice during an acute infection with the Colombiana T.cruzi strain and identified multiple miRNAs significantly altered upon infection. Seventeen miRNAs were found significantly deregulated in all three analyzed time points post infection. Among these, six miRNAs had their expression correlated with clinical parameters relevant to the disease, such as parasitemia and maximal heart rate-corrected QT (QTc) interval. Computational analyses identified that the gene targets for these six miRNAs were involved in networks and signaling pathways related to increased ventricular depolarization and repolarization times, important factors for QTc interval prolongation. The data presented here will guide further studies about the contribution of microRNAs to Chagas heart disease pathogenesis.

Ebi3 Prevents Trypanosoma cruzi-Induced Myocarditis by Dampening IFN-γ-Driven Inflammation

The identification of anti-inflammatory mediators can reveal important targetable molecules capable of counterbalancing Trypanosoma cruzi-induced myocarditis. Composed of Ebi3 and IL-27p28 subunits, IL-27 is produced by myeloid cells and is able to suppress inflammation by inducing IL-10-producing Tr1 cells, thus emerging as a potential candidate to ameliorate cardiac inflammation induced by T. cruzi. Although IL-27 has been extensively characterized as a suppressive cytokine that prevents liver immunopathogenesis after T. cruzi infection, the mechanisms underlying its effects on T. cruzi-induced myocarditis remain largely unknown. Here, wild-type (WT) and Ebi3-deficient animals were intraperitoneally infected with trypomastigotes of T. cruzi Y strain and used to evaluate the potential anti-inflammatory properties of Ebi3 during T. cruzi infection. The survival rates of mice were daily recorded, the frequency of inflammatory cells was analyzed by flow cytometry and inflammatory mediators were measured by ELISA, real-time PCR and PCR array. We reported that T. cruzi-induced myocarditis was prevented by Ebi3. Stressors mainly recognized by TLR2 and TLR4 receptors on myeloid cells were essential to trigger IL-27p28 production. In addition, Ebi3 regulated IFN-γ-mediated myocarditis by promoting an anti-inflammatory environment through IL-10, which was most likely produced by Tr1 cells rather than classical regulatory T cells (Tregs), in the heart tissue of T. cruzi-infected animals. Furthermore, in vivo IFN-γ blockade ameliorated the host survival without compromising the parasite control in the bloodstream. In humans, IL-27p28 was correlated with cardiac protection during Chagas disease. Patients with mild clinical forms of the disease produced high levels of IL-27p28, whereas lower levels were found in those with severe forms. In addition, polymorphic sites at Ebi3 gene were associated with severe cardiomyopathy in patients with Chagas disease. Collectively, we describe a novel regulatory mechanism where Ebi3 dampens cardiac inflammation by modulating the overproduction of IFN-γ, the bona fide culprit of Chagas disease cardiomyopathy.