Effects of bisphenol A on estrogen receptors-mediated calcium responses and proliferation of human peripheral T cells

• Main Authors: Pin-Tsun Kuo, 郭品岑
• Other Authors: Eileen Jea Chien
• Format: Others
• Language: zh-TW
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/j5kwat

碩士 === 國立陽明大學 === 生理學研究所 === 105 === Background: Bisphenol A (BPA) is an endocrine disrupting chemical (EDC) which has been used to produce polycarbonate plastics and epoxy resins and to coat metal cans. A lot of plastic tableware and detergents contain BPA, which is then easily accessed by the human body. BPA is able to mimic the effect of the natural hormone 17 β-estradiol and may interfere with the normal physiological function. BPA is able to stimulate an intracellular calcium concentration ([Ca2+]i) increase in T cells and this then results in a Th1/Th2 imbalance that seem to lead to the development of allergy or asthma in mice. A previous study by us found that the estrogen receptors ERα and ERβ together with a non-classical plasma membrane estrogen receptor, G-protein couple receptor (GPR30/GPER), are all expressed in T cells. E2 is able to stimulate rapid non-genomic responses and bring about the suppression of phytohemagglutinin (PHA)-activated T cell proliferation. Some studies have shown that classical ERα or ERβ and non-classical GPER are involved in [Ca2+]i increase, and even mimic estradiol through estrogen receptor. Thus, the aim of the study was to investigate in T cells firstly, which types of estrogen receptors are involved in bring about the rapid BPA-stimulated [Ca2+]i increase and, secondly, whether ER antagonists are able to block the rapid BPA-stimulated calcium increase and its suppressive effect on PHA-activated T cell proliferation. Method: Primary T cells were isolated from human peripheral blood and intracellular fura-2 fluorescence intensity was used to explore their responses on [Ca2+]i; in addition, cell toxicity and cell proliferation was determined by MTT assay. Results: (1) BPA concentration up to 100 μM affected T cell viability. (2) BPA rapidly stimulated the elevation of [Ca2+]i in a dose dependent manner. (3) The E2 or BPA stimulated [Ca2+]i elevation was blocked by U73122, a phospholipase C inhibitor, ICI182,780 (an estrogen selective antagonist), MPP (a ERα antagonist), PHTPP (a ERβ antagonist) and G-15 and G-36 (GPER antagonists). (3) When co-stimulation with E2 or BPA and PHA was carried out for 96 hours, PHA-activated T cell proliferation was suppress, E2 and BPA yet this suppressive effect was not released by co-incubation of the T cells with ICI 182, 780, MPP, PHTPP, G-15 or G-36. Conclusion: The rapid intracellular calcium increase brought about by BPA is blocked by various classical ER receptor antagonists and by GPER antagonists. However, none of these antagonists are able to release the immunosuppressive effect of PHA-activated T cell proliferation brought about by E2 or BPA. The ER receptor antagonists are able to block the non-genomic effect that stimulated by E2 or BPA but not the genomic immunosuppression effect. Thus, E2 or BPA causes an immunosuppression effect on T cell proliferation in vitro may not act through the rapid non-genomic effect. The possible mechanism of the action remains to be further explored.