Chagas cardiomyopathy is associated with a high susceptibility to T. cruzi infection in monocyte-derived macrophages and a predominance of CD4⁺CD45RO⁺ T-cells with immunoregulatory patterns

The pathogenesis of Chronic Chagas Cardiomyopathy (CCC) is still not fully understood, and the persistence of the parasite in tissues seems to be essential for the onset and progression of heart disease, tissue destruction, and chronic inflammation. It is clear that the polarity found between the asymptomatic (IND) and cardiac clinical forms refers mainly to the mechanisms involved in the regulation of the host's immune response. Thus, to elucidate aspects of the susceptibility of host phagocytes to T. cruzi infection, the present study explored novel aspects of innate immune response, integrating data on susceptibility to infection and intracellular replication, using monocyte-derived macrophages from CCC patients, together with memory CD4⁺ T-cells (CD45RO⁺). The isolation of PBMC was conducted by means of in vitro infection assay with T. cruzi trypomastigotes and flow cytometry analysis of the intracytoplasmic cytokine production by CD4⁺T-cells. Our findings indicated that monocytes derived from individuals with CCC are more susceptible to the infection and replication of intracellular amastigotes. Moreover, the stimulation of CD4⁺ T-cells from CCC patients, together with T. cruzi trypomastigotes, induces a predominance of a regulatory response over a type 1 response, demonstrated by an increase in IL-10 production and a reduction in the IFN-γ and IFN-γ/IL-10. Suppression of the function of monocyte-derived macrophages, from CCC patients, to control trypomastigote infection and intracellular replication sheds light on a potential susceptibility of these cells isolated from peripheral blood, which may reflect the ineffectiveness of parasite control by phagocytes in cardiac tissues, which can subsequently result in serious heart disease.