Bisphenol A and its substitutes regulate human B cell survival via Nrf2 expression

Abstract

B cells contribute to produce inflammatory cytokines and antibodies, to present autoantigens, and to interact with T cells, which lead to body defense and disease control. Nuclear factor (erythroid-derived 2)-like 2(Nrf2) is responsible for gene expression of antioxidant enzymes to protect cells from oxidative stress by reactive oxygen species(ROS) production. Bisphenol A(BPA) may not be safe due to the effect on body's physiological functions. The chemicals that substitute for BPA may still have similar effects in the body. Tritan™ copolyester is a novel plastic form using BPA substitutes, 1,4-cyclohexanedimethanol(CHDM), dimethyl terephthalate(DMT), and 2,2,4,4-tetramethyl-1,3-cyclobutanediol(TMCD). Isosorbide(ISO) was also used as a substitute for TMCD and DMT. Here, we investigated whether B cell viability is influenced by BPA and its substitutes via Nrf2 induction using WiL2-NS human B lymphoblast cells. When cytotoxicity was measured by using assays with MTT, CellTiter-Glo, trypan blue and propidium iodide, cytotoxicity by BPA was higher than that by substitutes. BPA and its substitutes showed significant cytotoxicity and ROS production, which were attenuated by the treatment with N-acetylcysteine(NAC), a ROS scavenger. In addition, BPA treatment enhanced gene expression of antioxidant enzymes, heme oxygenase(HO)-1, catalase, superoxide dismutase(SOD) 1 and 2. As H₂O₂ treatment induced cell death and Nrf2 amount in WiL2-NS cells, BPA treatment increased Nrf2. Cell death by H₂O₂ was increased in doxycycline-inducible Nrf2-knockdown(KD) cells. In Cytotoxicity by the treatment with BPA or its substitutes was also enhanced in Nrf2-KD cells but that was reduced by Nrf2 overexpression compared to control cells. Taken together, these results implicate that B cell cytotoxicity by substitutes should be lower than BPA and Nrf2 can prevent B cells from BPA- or BPA substitutes-induced cytotoxicity via ROS production. Data suggest that the comprehensive studies or evaluation could be necessary to replace BPA in manufacture by other substitutes.

Keywords: B cell; Bisphenol A; EDC; Nrf2; Reactive oxygen species; Substitute.