Trypanosoma cruzi infection induces a global host cell response in cardiomyocytes

Abstract

Chagas' disease, caused by the hemoflagellate protozoan Trypanosoma cruzi, affects millions of people in South and Central America. Chronic chagasic cardiomyopathy, the most devastating manifestation of this disease, occurs in approximately one-third of infected individuals. Events associated with the parasite's tropism for and invasion of cardiomyocytes have been the focus of intense investigation in recent years. In the present study, we use murine microarrays to investigate the cellular response caused by invasion of primary murine cardiomyocytes by T. cruzi trypomastigotes. These studies identified 353 murine genes that were differentially expressed during the early stages of invasion and infection of these cells. Genes associated with the immune response, inflammation, cytoskeleton organization, cell-cell and cell-matrix interactions, apoptosis, cell cycle, and oxidative stress are among those affected during the infection. Our data indicate that T. cruzi induces broad modulations of the host cell machinery in ways that provide insight into how the parasite survives, replicates, and persists in the infected host and ultimately defines the clinical outcome of the infection.

Fig. 1.

Number of DEGs at each time point. Each bar indicates the number of down- or upregulated genes for each time point.

Fig. 2.

Confirmation of microarray results by RT-PCR. Nine DEGs and their expression profiles are shown. The time points at which the differential expression was detected are shown schematically for each gene (A), and the RT-PCR result for each gene is represented as fold change (B). The RT-PCR analyses were performed on RNA extracted from infections in the late time period.

Fig. 3.

Functional analysis of DEGs during the infection of cardiomyocytes with Trypanosoma cruzi. The functional analysis identified the biological functions that were most significant to the data set. Genes from the data set associated with biological functions and/or diseases in the Ingenuity Pathways Knowledge Base (see Materials and Methods) were considered for the analysis. Fisher's exact test was used to calculate a P value determining the probability that each biological function and/or disease assigned to that data set is due to chance alone.

Fig. 4.

Heat map representations of DEGs associated with T. cruzi infection of primary murine cardiomyocytes. (A) DEGs associated with immune response (IR) and inflammation; (B) DEGs associated with cell cycle and apoptosis; (C) DEGs associated with cytoskeleton and intracellular trafficking; (D) DEGs associated with cell-cell and cell-matrix interactions; (E) DEGs associated with stress response and redox homeostasis. DEGs were classified according to their functions and the time point (E, early; I, intermediary; L, late) at which the gene was selected. Green squares, downregulation; red squares, upregulation.