Understanding the connection between exposure to mercury, auto-immunity and tolerance in B cells.

摘要 汞(Hg)是一种广泛存在于环境中的外来生物。汞也是一种有效的免疫调节剂。 这已被认为是导致动物模型和人类自身免疫性疾病的一个因素。一个 最近的流行病学研究现在令人信服地表明，在原本健康的人中，只有 通过典型的环境来源接触低水平的汞，血液中的汞与 自身免疫生物标记物双链DNA抗体的水平和在血液中的出现。这 研究结果表明，在适当的情况下，暴露在环境汞中会促进自身免疫， 自身免疫性疾病的先兆。自从B细胞被发现以来，免疫学家们已经意识到，在 根据克隆选择理论，在B细胞正常发育过程中，大量的 必须产生未成熟的B细胞，以产生与许多自身抗原(自身-免疫球蛋白)反应的免疫球蛋白。 抗体)。然而，在正常发育过程中，绝大多数未成熟的自身反应性B细胞 通过统称为容忍的过程来防止成熟。自身免疫性疾病在以下情况下发生 促进宽容的机制被打乱了。对于B细胞，已经牢固地建立了耐受性 在很大程度上取决于未成熟B细胞中B细胞受体(BCR)产生的信号。我们的 初步和最近发表的研究表明，汞干扰脑干听觉诱发电位的信号产生 未成熟的B细胞，通过可能涉及酪氨酸激酶Lyn，即酪氨酸磷酸酶的机制 SHP-1、CD45和细胞骨架元件。我们的总体假设是，环境暴露于 与非汞暴露的动物相比，汞暴露的动物扰乱了BCR信号，导致B细胞的破坏 暴露动物的细胞耐受性。这反过来应该导致成熟汽车的过度出现-- 汞暴露动物体内可能导致自身免疫性疾病的反应性B细胞。我们建议 通过建立抗鸡蛋溶菌酶(HEL)/鸡蛋溶菌酶双转基因小鼠来验证这一假设 它们被设计成对HEL正常耐受，并将它们暴露在汞中或不暴露在汞中，以便打破 HELL容忍(目标1)。我们将在我们的初步数据的基础上进一步阐明分子机制 这使得汞能够干扰BCR信号。我们将利用不同基因的小鼠品系 汞中毒易感性直接研究汞如何干扰酪氨酸功能 蛋白酪氨酸激酶Lyn和酪氨酸磷酸酶SHP-1和CD45在bcr信号转导中的作用 不同的遗传背景(目标2)。我们将使用互补蛋白质组和多色磷光 确定汞如何与细胞骨架元素相互作用从而衰减的细胞学方法 BCR信令(目标3)。

ABSTRACT Mercury (Hg) is a xenobiotic that is widespread in the environment. Mercury is also a potent immunomodulator that has been implicated as a factor contributing to autoimmune disease in animal models and humans. A recent epidemiological study has now convincingly shown that, in otherwise healthy individuals who were only exposed to low levels of Hg through typical environmental sources, there is a correlation between blood Hg levels and the appearance in the blood of antibodies to double-stranded DNA, an autoimmune biomarker. This finding indicates that under the proper circumstances, exposure to environmental Hg promotes autoimmunity, a precursor to autoimmune disease. Since the discovery of B cells, immunologists have appreciated that, in light of the Clonal Selection Theory, during the normal course of B cell development, large numbers of immature B cells must be generated that produce immunoglobulin that is reactive to many self-antigens (auto- antibodies). However, in the course of normal development, the vast majority of immature auto-reactive B cells are prevented from maturing by processes collectively known as tolerance. Autoimmune disease arises when the mechanisms that promote tolerance are disrupted. For B cells, it is firmly established that tolerance depends to a large extent on signals generated by the B cell receptor (BCR) in immature B cells. Our preliminary and recently published studies have shown that Hg interferes with signal generation by the BCR in immature B cells, through mechanisms that likely involve the tyrosine kinase Lyn, the tyrosine phosphatases SHP-1 and CD45 and elements of the cytoskeleton. Our overall hypothesis is that environmental exposure to Hg disrupts BCR signaling in Hg-exposed compared with non-exposed animals, resulting in the disruption of B cell tolerance in exposed animals. This in turn should lead to the appearance of an excess of mature auto- reactive B cells in Hg-exposed animals that have the potential to cause autoimmune disease. We propose to test this hypothesis by generating anti-hen egg lysozyme (HEL)/hen egg lysozyme double transgenic mice which are designed to be normally tolerant to HEL, and them exposing them or not to Hg, in order to break HEL tolerance (Aim 1). We will expand on our preliminary data to further elucidate the molecular mechanisms that enable Hg to interfere with BCR signaling. We will utilize mouse strains with different genetic susceptibilities to Hg intoxication to directly investigate how Hg interferes with the function of the tyrosine kinase Lyn and the tyrosine phosphatases SHP-1 and CD45 during BCR signaling under the influence of different genetic backgrounds (Aim 2). We will use complementary proteomic and multicolor phosphoflow cytometric approaches to determine how Hg interacts with elements of the cytoskeleton, so as to attenuate BCR signaling (Aim 3).