IMMUNOTOXICOLOGY OF A HEAVY METAL

重金属的免疫毒理学

• 批准号: 2459028
• 负责人: Kenneth Michael Pollard
• 金额: $ 18.82万
• 依托单位: SCRIPPS RESEARCH INSTITUTE, THE
• 依托单位国家: 美国
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-08-01 至 1999-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2459028
• 关键词: autoantibody; autoimmune disorder; environmental toxicology; immunotoxicity; laboratory mouse; mercury poisoning; nonhistone nucleoprotein; protease inhibitor; protein purification; protein sequence; protein structure function; ribonucleoproteins; scleroderma; serine proteinases

DESCRIPTION (Adapted from the Investigator's Abstract): Exposure to toxins and chemicals, including drugs, can produce aberrant immune reactions which may include autoimmunity. The observation which continues to elude explanation in chemical-induced autoimmunity is the restriction of autoantibody responses to a single, or a limited number of intracellular antigens, the specificity of which appears dependent in part upon the chemical involved. The investigator has shown that the heavy metal mercury induces a genetically restricted autoantibody response in mice that predominantly targets the nucleolar protein fibrillarin. This murine autoantibody response bears remarkable similarity to the anti-fibrillarin response in human scleroderma. Although the investigator's preliminary studies show that interaction of viable cells or isolated nuclei with mercuric chloride leads to modification of the molecular properties of fibrillarin, anti- fibrillarin autoantibodies do not appear to be directed against a fibrillarin-mercury complex. This suggests that mercury modification of fibrillarin may influence antigen processing of T cell responses associated with anti-fibrillarin autoantibody production. This is supported by additional preliminary studies showing that mercury causes apoptotic-like cell death in macrophages which is associated with proteolytic activity. Preliminary studies show that addition of exogenous fibrillarin to lysates from HgCl2 killed, but not untreated (control) macrophages results in proteolytic cleavage of the protein. This proteolytic activity is inhibited by serine protease inhibitors, showing it to be unrelated to apoptosis cysteine proteases of the ICE/CED-3 family. It is the aim of this proposal to test the hypothesis that this combination of interaction with mercury and digestion by protease leads to enhanced immunogenicity of fibrillarin, which stimulates autoreactivity among T and B cells and autoantibody production in mice of the appropriate H-2 genotype. Mercury modification of fibrillarin will be examined by mutation of the fibrillarin sequence to determine the residues responsible for the observed change in the molecular properties of fibrillarin upon interaction with mercury. Purified wild type and mutated fibrillarin, in the presence and absence of mercury, will be tested for their ability to elicit T cell and B cell responses to determine if mercury modified fibrillarin is sufficient to elicit an autoimmune response with properties similar to that produced by mercury in vivo. The significance of the protease digestion of fibrillarin in the autoimmune response will be determined by isolation of the protease to allow examination of the expression and cellular localization of the protease. The protease will also be used for the digestion of wild type and mutated fibrillarin to examine the potential of proteolytic fragments to stimulate T and B cells from mice sensitive and resistant to mercury-induced autoimmunity. By analyzing the ability of mercury modified fibrillarin to interact with cells of the lymphoid system insights might be gained as to how an immunotoxin renders a self antigen immunogenic. Such observations may be of significance in understanding immunotoxicity of other heavy metals and xenobiotics in general.

描述（根据调查员的摘要改编）：暴露于 毒素和化学物质（包括药物）会产生异常免疫 可能包括自身免疫性的反应。观察结果 在化学引起的自身免疫性中继续避免解释 对单个或有限数量的自身抗体响应的限制 细胞内抗原，其特异性似乎取决于 部分涉及化学物质。调查人员表明 重金属汞诱导遗传限制的自身抗体 主要针对核仁蛋白的小鼠的反应 纤维林。这种鼠自身抗体反应具有显着 与人硬皮病中的抗纤维蛋白反应相似。 尽管研究者的初步研究表明 有生存的细胞或用氯化汞的分离核导致 纤维蛋白，抗抗菌的分子特性的修饰 纤维林自身抗体似乎并未针对 纤维林 - 汞综合体。这表明汞修改 纤维林可能影响T细胞反应的抗原加工 与抗纤维林自身抗体产生有关。这是 在其他初步研究的支持下，表明汞原因 巨噬细胞中的凋亡样细胞死亡与 蛋白水解活性。初步研究表明，添加 来自HGCL2的裂解物的外源纤维蛋白被杀死，但未治疗 （对照）巨噬细胞导致蛋白质的蛋白水解切割。 这种蛋白水解活性受到丝氨酸蛋白酶抑制剂的抑制， 表明它与凋亡的半胱氨酸蛋白酶无关 ICE/CED-3家族。 该提议的目的是检验假设 通过汞与消化的互动的结合 蛋白酶导致纤维林的免疫原性增强，这 刺激T和B细胞之间的自动反应性以及自身抗体的产生 在适当的H-2基因型的小鼠中。汞修饰 纤维林将通过纤维林序列的突变来检查 确定负责观察到的变化的残留物 纤维林与汞相互作用后的分子特性。 在存在和不存在的情况下，纯化的野生型和突变的纤维蛋白 汞的含量，将测试其引起T细胞和B细胞的能力 确定汞修饰的纤维林是否足以 引发具有类似于产生的特性的自身免疫反应 由水星在体内。蛋白酶消化的意义 自身免疫反应中的纤维林将通过隔离确定 蛋白酶允许检查表达和细胞 蛋白酶的定位。蛋白酶也将用于 野生型和突变的纤维蛋白的消化以检查电势 蛋白水解片段以刺激小鼠敏感的T和B细胞 并抵抗汞引起的自身免疫性。通过分析能力 汞修饰的纤维林与淋巴样细胞相互作用 对于免疫毒素如何产生自我，可能会获得系统见解 抗原免疫原性。这样的观察可能在 了解其他重金属和异种生物的免疫毒性 一般的。