Splenic Toxicity of Aniline

描述(申请人提供)：我们的长期目标是阐明芳香胺对脾的毒性机制，并开发预防和治疗策略。以苯胺为原型化合物，在我们之前的资助期间的研究表明，大鼠暴露于苯胺会导致脾内氧化应激，明显表现为活性铁、脂质过氧化、蛋白质氧化、DMA氧化、脂质衍生的醛-蛋白质加合物和硝基酪氨酸的增加。伴随这些变化的是转录因子NF-kappaB和AP-1的激活，以及纤维化和炎性细胞因子的上调。形态上，脾血管充血，血窦细胞和成纤维细胞增多，红髓细胞增多，包膜增厚，纤维化。在确定了氧化应激在苯胺的脾毒性中的重要作用后，我们现在将把我们的研究转向苯胺诱导的氧化应激途径，这些途径导致脾纤维化和肿瘤发生。我们假设，由于过量产生氧化剂(ROS和RNS)，苯胺诱导的氧化应激激活了氧化还原敏感的转录因子(NF-kappaB和AP-1)，导致脾中参与纤维化和细胞生长调节通路的基因转录。此外，对DNA的氧化损伤会导致基因突变。这些事件，单独或共同发生，导致脾纤维化和/或肿瘤形成。这一假说将通过追求三个特定的目标来验证：目标1将阐明转录因子NF-kappaB和AP-1的调节，信号机制和相关基因在苯胺脾毒性中的表达。目的研究DNA氧化损伤和修复、丙二醛-DNA加合物、DNA甲基化和抑癌基因P53突变在苯胺诱导的脾毒性中的作用。目的通过研究诱导型一氧化氮合酶(INOS)和硝化蛋白的形成，以及NO/ONOO在调节核因子-kappaB活化、细胞因子表达和DNA损伤中的作用，探讨活性氮在脾损伤中的作用。这些研究将阐明苯胺引起的脾毒性的机制，并将对制定预防毒性的策略以及对苯胺和其他结构相关的芳香胺的风险评估具有重要意义。

DESCRIPTION (provided by applicant): Our long-term objective is to elucidate the mechanisms of the splenic toxicity of aromatic amines, and to develop preventive and therapeutic strategies. Using aniline as a prototypic compound, studies in our previous funding period demonstrated that aniline exposure in rats leads to oxidative stress in the spleen, evident from increases in reactive iron, lipid peroxidation, protein oxidation, DMA oxidation, lipid-derived aldehyde-protein adducts and nitrotyrosine. These changes are accompanied by activation of the transcription factors NF-kappaB and AP-1, and up-regulation of fibrogenic and inflammatory cytokines. Morphologically, spleen showed vascular congestion, increased red pulp cellularity due to increased sinusoidal cells and fibroblasts, capsular thickening and fibrosis. Having established the important role of oxidative stress in the splenic toxicity of aniline, we will now direct our studies toward the aniline-induced oxidative stress pathways that lead to splenic fibrosis and tumorigenesis. We hypothesize that aniline-induced oxidative stress due to over-production of oxidants (ROS and RNS) activates redox-sensitive transcription factors (NF-kappaB and AP-1) leading to transcription of genes involved in fibrosis and cell growth regulatory pathways in the spleen. Furthermore, oxidative damage to DNA leads to gene mutations. These events, individually or in concert, lead to fibrosis and/or tumorigenesis in the spleen. This hypothesis will be tested by pursuing three specific aims: Aim 1 will elucidate the regulation of transcription factors NF-kappaB and AP-1, signaling mechanisms and related gene expression in the splenic toxicity of aniline. Aim 2 will examine the role of oxidative DNA damage and repair, malondialdehyde-DNA adducts, DNA methylation, and mutations in the tumor suppressor gene p53 in aniline-induced splenic toxicity. Aim 3 will investigate the contribution of reactive nitrogen species to splenic damage by characterizing iNOS regulation and the formation of nitrated proteins, and by examining the role of NO/ONOO in the regulation of NF-kappaB activation, cytokine expression and DNA damage. These studies will elucidate the mechanisms of aniline-induced splenic toxicity, and will be important in devising strategies to prevent toxicity, and in risk assessment of aniline and other structurally-related aromatic amines.