Polymorphisms in Genes Affecting Interferon-γ Production and Th1 T Cell Differentiation Are Associated With Progression to Chagas Disease Cardiomyopathy.

Background:Chagas disease, caused by the protozoanTrypanosoma cruzi, is endemic in Latin America. Thirty percent of infected individuals develop chronic Chagas cardiomyopathy (CCC), an inflammatory dilated cardiomyopathy that is the most important clinical consequence ofT. cruziinfection, while the others remain asymptomatic (ASY). IFN-gamma and IFN-gamma-producing Th1-type T cells are increased in peripheral blood and CCC myocardium as compared to ASY patients, while the Th1-antagonizing cytokine IL-10 is more expressed in ASY patients. Importantly IFN-gamma-producing Th1-type T cells are the most frequent cytokine-producing T cell subset in CCC myocardium, while expression of Th1-antagonizing cytokines IL-10 and IL-4 is unaltered. The control of IFN-gamma production by Th1-type T cells may be a key event for progression toward CCC. A genetic component to disease progression was suggested by the familial aggregation of cases and the association of gene polymorphisms with CCC development. We here investigate the role of gene polymorphisms (SNPs) in several genes involved in the control of IFN-gamma production and Th1 T cell differentiation in CCC development. Methods:We studied a Brazilian population including 315 CCC cases and 118 ASY subjects. We assessed 35 Tag SNPs designed to represent all the genetic information contained in theIL12B, IL10, IFNG, andIL4genes. Results:We found 2IL12SNPs (rs2546893, rs919766) and a trend of association for aIL10SNP (rs3024496) to be significantly associated with the ASY group. these associations were confirmed by multivariate analysis and allele tests. The rs919766C, 12rs2546893G, and rs3024496C alleles were associated to an increase risk to CCC development. Conclusions:Our data show that novel polymorphisms affectingIL12BandIL10, but notIFNGorIL4genes play a role in genetic susceptibility to CCC development. This might indicate that the increased Th1 differentiation and IFN-gamma production associated with CCC is genetically controlled.