The flame retardant DE-71 (a mixture of polybrominated diphenyl ethers) inhibits human differentiated thyroid cell function in vitro

Abstract

BackgroundNormal thyroid function is essential for general growth and metabolism, but can be affected by endocrine disrupting chemicals (EDCs). Polybrominated diphenyl ethers (PBDEs) have been used worldwide to reduce flammability in different materials and are suspected to be EDCs. The production of the commercial Penta- and OctaBDE mixtures is banned, but DecaBDEs and existing products may leak PBDEs into the environment. Our aim was to investigate the effect of the PentaBDE mixture DE-71 on human thyroid cells in vitro.Materials and methodsPrimary human thyroid cells were obtained as paraadenomatous tissue and cultured in monolayers. The influence of DE-71 on cyclic adenosine monophosphate (cAMP) and thyroglobulin (Tg) production was examined in the culture medium by competitive radioimmunoassay and enzyme-linked immunosorbent assay, respectively. Real-time quantitative PCR analysis of thyroid-specific genes was performed on the exposed cell cultures. PBDE concentrations were determined in cellular and supernatant fractions of the cultures.ResultsDE-71 inhibited Tg-release from TSH-stimulated thyrocytes. At 50 mg/L DE-71, mean Tg production was reduced by 71.9% (range: 8.5–98.7%), and cAMP by 95.1% (range: 91.5–98.8%) compared to controls). Expression of mRNA encoding Tg, TPO and TSHr were significantly inhibited (p<0.0001, p = 0.0079, and p = 0.0002, respectively). The majority of DE-71 added was found in the cell fraction. No cytotoxicity was found.ConclusionsDE-71 inhibited differentiated thyroid cell functions in a two phase response manner and a concentration-dependent inhibition of Tg and cAMP production, respectively, as well as expression of mRNA encoding Tg, TPO and TSHr. Our findings suggest an inhibiting effect of PBDEs on thyroid cells.

Thyroid Disrupting Chemicals

“…DE71 inhibited differentiated thyroid cell functions in a two phase response manner and a concentration-dependent inhibition of thyroglobulin (Tg) and cAMP production, respectively, as well as expression of mRNA encoding Tg, thyroid peroxidase (TPO) and TSH receptor. This study confirmed an inhibiting effect of PBDEs on thyroid cells [20].…”

Thyroid Disrupting Chemicals

“…DE71 inhibited differentiated thyroid cell functions in a two phase response manner and a concentration-dependent inhibition of thyroglobulin (Tg) and cAMP production, respectively, as well as expression of mRNA encoding Tg, thyroid peroxidase (TPO) and TSH receptor. This study confirmed an inhibiting effect of PBDEs on thyroid cells [ 23 ].…”

Ghrelin-mediated inhibition of the TSH-stimulated function of differentiated human thyrocytes ex vivo

“…Cells were harvested as described above, and the cAMP concentration was measured by a competitive protein binding method as described elsewhere [ 51 ] in which paper controls stimulating cells with forskolin were performed. The detection limit of the assay was 0.004 μM [ 52 ]. The calibration range was 0.05 to 2.0 μM.…”

“…Sulphuric acid (0.18 M) was added to stop the reaction and the results were measured by an ELISA reader (BioTek Synergy 2) at 450 nm. The calibration range was 10 to 500 μg/L [ 52 ]. When ELISA was performed, the samples were diluted until Tg levels measured were in compliance with the detection range.…”

“…The intra-assay variation at the concentration of 52 μg/L was 9.5% and 8% at 101 μg/L (n = 7 and 6 duplicates for the low and high control level, respectively). For the low control, the inter-assay variation was 22.3% (range 32–65 μg/L) and 17.5% for the high control (65–121 μg/L) (n = 5 samples in duplicates for each control) [ 52 ].…”