Alternative Th17 and CD4+ CD25+ FoxP3+ cell frequencies increase and correlate with worse cardiac function in Chagas cardiomyopathy.

Abstract

Immune homeostasis has been suggested to play an important role in the clinical evolution of chronic Chagas disease; however, the immunopathologic factors involved have not been fully elucidated. Therefore, our study aimed to analyse the frequency of CD4+ CD25+ FoxP3+ cells, classic Th17 cells, alternative Th17 cells and IL-17+ B cells from peripheral blood of chronic cardiac patients after invitro stimulation with Trypanosoma cruzi soluble EPI antigen. Patients were selected and classified according to clinical evaluation of cardiac involvement: mild, B1 (CARD1) (n=20) and severe, C (CARD2) (n=11). Patients with the indeterminate form of CD were included as the control group A (IND) (n=17). Blood samples were collected and cultured in the presence of EPI antigen. Cells frequency and median fluorescence intensity (MFI) were obtained by flow cytometry. Our results showed that only CD4+ CD25+ FoxP3+ , CD4+ CD25high FoxP3+ , CD4+ IL-17+ IFN-γ- and CD4+ IL-17+ IFN-γ+ cells are more frequent in patients with severe cardiac disease and correlate with worse global cardiac function. However, while indeterminate patients demonstrated a positive correlation between CD4+ CD25+ FoxP3+ and CD4+ IL-17+ IFN-γ- Th17 cells, this relationship was not observed in cardiac patients. IL-17 expression by Th17 cells and B cells correlated with disease progression. Altogether our results suggest that the clinical progression of Chagas cardiomyopathy involves worsening of inflammation and impairment of immunoregulatory mechanisms.