Improved Biomarker and Imaging Analysis for Characterizing Progressive Cardiac Fibrosis in a Mouse Model of Chronic Chagasic Cardiomyopathy

BACKGROUND: Chronic chagasic cardiomyopathy (CCC), caused by Trypanosoma cruzi infection, is an important public health problem attributable to progressive cardiomyopathy in patients, for which there is no cure. Chronic chagasic cardiomyopathy is characterized by myocarditis and cardiac fibrosis, which leads to life‐threatening arrhythmogenic and circulatory abnormalities. This study aimed to investigate cardiac fibrosis progression in a mouse model of chronic chagasic cardiomyopathy. METHODS AND RESULTS: Cardiac cells infected with T cruzi produced significantly higher concentrations of transforming growth factor‐β (TGF‐β), connective tissue growth factor, endothelin‐1, and platelet‐derived growth factor‐D than noninfected controls. Female Balb/c mice infected with T cruzi were compared with naïve mice. TGF‐β genes and other TGF‐β superfamily genes, as well as connective tissue growth factor, endothelin‐1, and platelet‐derived growth factor, were upregulated in infected mouse hearts. Serum concentrations of TGF‐β, connective tissue growth factor, and platelet‐derived growth factor‐D were higher in infected mice and correlated with cardiac fibrosis. Strain analysis performed on magnetic resonance images at 111 and 140 days postinfection and echocardiography images at 212 days postinfection revealed significantly elevated left ventricular strain and cardiac fibrosis and concomitantly significantly decreased cardiac output in infected mice. CONCLUSIONS: TGF‐β, connective tissue growth factor and platelet‐derived growth factor‐D are potentially useful biomarkers of cardiac fibrosis, as they correlate with cardiac fibrosis. Strain analysis allows for use of noninvasive methods to measure fibrosis in the chronic stages of chagasic cardiomyopathy in a mouse model. These findings can be applied as noninvasive tools to study the effects of interventions and/or therapeutics on cardiac fibrosis development when using a mouse model of chronic chagasic cardiomyopathy.