Hypothyroidism impairs the host immune response during the acute phase of Chagas disease

[Display omitted] •We have investigated the influence of hypothyroidism in the course of acute Trypanosoma cruzi infection.•Infected rats have higher IFN-γ and IL-17A levels compared with non-infected controls.•B cells and the ability of antigenic presentation of macrophages are negatively correlated with hypothyroidism in the chagasic infection.•Infected hypothyroid animals have higher thymic cell death compared with infected non-hypothyroid controls.•Hypothyroidism impairs the host immune response during the acute phase of Chagas disease. Diseases associated with thyroid hypofunction have been the subject of studies in infectious models, since several authors have demonstrated a pivotal role of iodinated hormones (thyroxine and triiodothyronine) in the modulation of immune effector responses. Using a model of hypothyroidism induced by anti-thyroid drug, we investigated the influence of hypothyroidism in the course of acute Trypanosoma cruzi infection. For this, male Hannover Wistar rats were challenged with methimazole for 21 days (0.02% in drinking water), and water for control counterparts. After confirmation of the hypothyroidism, rats were intraperitoneally challenged with 1x105 blood trypomastigotes of the Y strain of T. cruzi. Our findings suggest that hypothyroidism impairs animal weight gain, but does not affect the health of essential organs. Interestingly, infected hypothyroid animals had a significant increase in thymic cell death, with consequent drop in lymphocyte frequency in whole blood (evaluated on the 11th day of infection). Analyzing the percentage of immune cells in the spleen, we found a strong influence of hypothyroidism as a negative regulator of B cells, and antigenic ability of macrophages (RT1b expression) in the course of the experimental chagasic infection. Enhanced serum IL-17A concentration was induced by T. cruzi infection, but hypothyroidism impaired the production of this mediator as seen in infected hypothyroid animals. Taken together, our work suggests for the first time that hypothyroidism may adversely interfere with the modulation of effective immunity in the early phase of Chagas' disease.