Chronic Chagasic Cardiopathy: The Product of a Turbulent Host-Parasite Relationship

Abstract

The pathogenesis of chronic chagasic cardiopathy is still a debated matter. In this review, the main theories raised about it since the first description of the disease in 1909 by Carlos Chagas, are considered. The scarcity of T.cruzi parasites into the myocardium and the apparent lack of correlation between their presence and the occurrence of myocardial inflammatory infiltrate, have originated many theories indicating that chronic Chagas' cardiopathy is an autoimmune disease. Recently however, papers using immunohistochemical technique or PCR have demonstrated a strong association between moderate or severe myocarditis and presence of T.cruzi Ags, indicating a direct participation of the parasite in the genesis of chronic chagasic myocarditis. Different patterns of cytokine production seem to have important role in the outcome of the disease. Participation of the microcirculatory alterations and fibrosis as well as the relationship with the parasite are also emphasized. Finally, the author suggests that the indeterminate form of the disease occurs when the host immunological response against the parasite is more efficient while the chronic cardiopathy occurs in patients with hyperergic and inefficient immune response.

Avaliação do metabolismo dos fosfatos de alta energia em pacientes com doença de Chagas

“…With the coil located on the left ventricular anterior wall, we set up a volume of approximately 35 cm 3 , which was placed parallel to the surface coil. The volume selected contains, predominantly, cardiac muscle of the left ventricular anterior apical region.…”

“…The pathogenesis of Chagas' heart disease is not established, and the proposed mechanisms are [3][4][5][6] : direct aggression to the myocardium by T. cruzi; neurogenic hypothesis based on phosphocreatine (PCr) 13 . Thus, phosphorus-31 magnetic resonance spectroscopy (MRS) enables the evaluation of high-energy phosphates found in the myocardium, allowing the identification of metabolic changes in patients with different degrees of myocardial impairment 14,15 .…”

Chagas' heart disease

“…In addition, molecular biology techniques now permit the detection of circulating T. cruzi antigens in a much larger contingent of chagasic patients in whom the conventional serologic methods fail for such purpose 117,118 . It is plausible to speculate that even low-grade persistent parasitism may lead to a continuous antigenic feedback loop to the autoimmune system, which may constitute the main damaging mechanism in the late phase [119][120][121] .…”

The pathogenesis of Chagas' disease: when autoimmune and parasite-specific immune responses meet

“…The specificity of the pathogenic immune response, however, is the source of the controversy. One main hypothesis proposes that the pathogenic inflammatory response is exclusively directed to T. cruzi antigens at sites of parasite persistence (Tarleton 2001, Higuchi 1997. The second main hypothesis is that CChC is an autoimmune disease triggered in some individuals by T. cruzi infection (Cunha-Neto and Kalil 1995, .…”