Uncovering the effects of thyroid disruption on immune development and function in fathead minnows (PIMEPHALES PROMELAs)

Abstract

Previous studies showed that exposures to thyroid inhibitors during early stages of development lead to long-lasting alterations in disease resistance. Therefore, the goal of this project was to assess the effects of early life stages thyroid disruption on the maturation and function of immune cells using propylthiouracil (PTU)-exposed fathead minnow as a model system. The specific objectives of this study were to evaluate the impacts of early life stage PTU-exposure on 1) transcriptomic markers of lymphoid and myeloid cell development and 2) neutrophil migration. These objectives were accomplished by exposing fathead minnow embryos to 35 mg/L and 70 mg/L PTU for 10 days, while assessing immune cell development by measuring transcriptomic markers of maturation at 5, 7 and 10 days post fertilization (dpf) and evaluating neutrophils migration with a tail nicking assay at 10 dpf. There were no differences in transcriptomic markers for lymphoid cells between PTU and control groups. However, PTU-exposed larvae showed a decreased expression of v-myb gene and had less neutrophils at wound site compared to those of the control at days 7 and 10, indicating that early life thyroid disruption interfered with the normal development and function of these immune cells.