Bisphenol A (BPA) is the best-known representative of bisphenols, found in many consumer products, air, drinking water, human biological samples etc. Due to the alarming effects of this endocrine disrupting chemical (EDC) on human health, the European Commission has restricted or even banned its use in the manufacture and import of some consumer products and the European Food Safety Authority (EFSA) has since lowered its tolerable daily intake. This in turn increased the use of its many structural analogues, which are already detectable in the environment and human fluids. BPA analogues are particularly problematic due to data scarcity on their action mechanisms and effects.
The aim of this thesis was to study the effect of seven bisphenols, BPA, BPAP, BPE, BPP, BPS-MAE, BPZ and TCBPA, on metabolic activity and immunomodulation in the monocyte cell line THP-1, which were differentiated into macrophages. The effect of selected bisphenols on metabolic activity was determined by resazurin assay and fluorescence measurement, and the mean inhibitory concentration (IC50) of each bisphenol was determined, where 50% of the cells were metabolically active. The lowest IC50 was determined for BPP (19,1 ± 0,3 μM), which is therefore the most cytotoxic. BPAP (37,1 ± 1,2 μM), BPZ (43,5 ± 2,3 μM), TCBPA (64,4 ± 7,6 μM), BPA (122,6 ± 5,7 μM) and BPS-MAE (137,5 ± 7,0 μM) followed, with BPE being the least cytotoxic (220,2 ± 47,7 μM). We also found that there is a correlation between lipophilicity (logP) and cytotoxicity.
The effect of three concentrations of bisphenols, 10 nM, 100 nM and 10 μM, on the modulation of cytokines of THP-1 macrophages activated by lipopolysaccharide (LPS) was then investigated by flow cytometry. Bisphenols were mostly pro-inflammatory, as they increased the release of inflammatory cytokines. At the lowest concentration, there was a significant decrease in the inflammatory cytokine IL-1β (BPE) and a significant increase in the pleiotropic cytokine IL-6 (BPA), while there was a significant increase of the inflammatory cytokines IL-1β (BPE, BPP and TCBPA) and IL-6 (TCBPA) at the medium concentration. The highest concentration caused both a significant increase (TCBPA) and decrease (BPA and BPP) of the inflammatory cytokine IL-1β and increases of the pleiotropic cytokine IL-6 (BPS-MAE, BPZ in TCBPA) and the inflammatory cytokine IL-8 (TCBPA).
In conclusion, BPA analogues have immunomodulatory properties, with pro-inflammatory effects at the concentrations found in body fluids, and some anti-inflammatory effects at higher, micromolar concentrations.
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