Exercise training reduces cardiac fibrosis, promoting improvement in arrhythmias and cardiac dysfunction in an experimental model of chronic chagasic cardiomyopathy.

BACKGROUND

Chagas disease, caused by the parasite , is associated with inflammation and fibrosis, which characterizes chronic Chagasic cardiomyopathy (CCC). CCC manifests as arrhythmias, hypertrophy or dilation of the left ventricle, and it may progress to heart failure. Therefore, interventions are needed to slow the progression of CCC. Aims: We investigated the effects of exercise training in an animal model of CCC.

METHODS

C57BL/6 mice infected with were submitted to a progressively treadmill exercise training protocol. The cardiac function was evaluated by echocardiogram and electrocardiogram. RT-qPCR and morphometric analyses were performed on samples of cardiac tissue to quantify inflammation and fibrosis.

RESULTS

EKG analysis confirmed that all infected mice developed arrhythmias, with different degrees of severity. Exercise improved arrhythmias in 43.75% of chagasic trained mice, and the remaining mice did not show any alteration in EKG. The untrained chagasic group had no improvement in arrhythmias. The ventricular compliance in chagasic trained mice increased, as revealed by the reduction in isovolumetric relaxation time when compared to untrained mice. Exercise induced the reduction of gene expression of TGF-β, TNF-α, IL-1β, IL-6 and MMP-9 and reduced fibrosis in the heart tissue of chagasic mice.

CONCLUSION

Exercise reduced fibrosis in the heart and skeletal muscle, favoring the improvement of arrhythmias, and augment of cardiac complacency in mice with CCC, in addition to decreasing the expression of profibrotic and proinflammatory genes in the heart.