Dogs infected with the blood trypomastigote form of Trypanosomacruzi display an increase expression of cytokines and chemokines plusan intense cardiac parasitism during acute infection.

Abstract

The recent increase in immigration of people from areas endemic for Chagas disease (Trypanosoma cruzi)to the United States and Europe has raised concerns about the transmission via blood transfusion andorgan transplants in these countries. Infection by these pathways occurs through blood trypomastigotes(BT), and these forms of T. cruzi are completely distinct of metacyclic trypomastigotes (MT), releasedby triatomine vector, in relation to parasite–host interaction. Thus, research comparing infection withthese different infective forms is important for explaining the potential impacts on the disease course.Here, we investigated tissue parasitism and relative mRNA expression of cytokines, chemokines, andchemokine receptors in the heart during acute infection by MT or BT forms in dogs. BT-infected dogspresented a higher cardiac parasitism, increased relative mRNA expression of pro-inflammatory andimmunomodulatory cytokines and of the chemokines CCL3/MIP-1 _, CCL5/RANTES, and the chemokinereceptor CCR5 during the acute phase of infection, as compared to MT-infected dogs. These results suggestthat infection with BT forms may lead to an increased immune response, as revealed by the cytokinesratio, but this kind of immune response was not able to control the cardiac parasitism. Infection with theMT form presented an increase in the relative mRNA expression of IL-12p40 as compared to that of IL-10or TGF- _1. Correlation analysis showed increased relative mRNA expression of IFN- _ as well as IL-10,which may be an immunomodulatory response, as well as an increase in the correlation of CCL5/RANTESand its CCR5 receptor. Our findings revealed a difference between inoculum sources of T. cruzi, as vectorialor transfusional routes of T. cruzi infection may trigger distinct parasite–host interactions during the acutephase, which may influence immunopathological aspects of Chagas disease.