Levels of circulating anti-muscarinic and anti-adrenergic antibodies and their effect on cardiac arrhythmias and dysautonomia in murine models of Chagas disease.

Antibodies (Ab) recognizing G-protein coupled receptors, such as β 1 and β 2 adrenergic (anti- β 1 -AR and anti- β 2 -AR, respectively) and muscarinic cholinergic receptors (anti-M 2 -CR) may contribute to cardiac damage, however their role in chronic chagasic cardiomyopathy is still controversial. We describe that Trypanosoma cruzi -infected C3H/He mice show increased P and QRS wave duration, and PR and QTc intervals, while the most significant ECG alterations in C57BL/6 are prolonged P wave and PR interval. Echocardiogram analyses show right ventricle dilation in infected animals of both mouse lineages. Analyses of heart rate variability (HRV) in chronically infected C3H/He mice show no alteration of the evaluated parameters, while C57BL/6 infected mice display significantly lower values of HRV components, suggesting autonomic dysfunction. The time-course analysis of anti- β 1 -AR, anti- β 2 -AR and anti-M 2 -CR Ab titres in C3H/He infected mice indicate that anti- β 1 -AR Ab are detected only in the chronic phase, while anti- β 2 -AR and anti-M 2 -CR are observed in the acute phase, diminish at 60 dpi and increase again in the chronic phase. Chronically infected C57BL/6 mice presented a significant increase in only anti-M 2 -CR Ab titres. Furthermore, anti- β 1 -AR, anti- β 2 -AR and anti-M 2 -CR, exhibit significantly higher prevalence in chronically T. cruzi -infected C3H/He mice when compared with C57BL/6. These observations suggest that T. cruzi infection leads to host-specific cardiac electric alterations.