Splenic Toxicity of Aniline

描述（由申请人提供）：我们的长期目标是阐明芳香胺的脾毒性机制，并制定预防和治疗策略。使用苯胺作为原型化合物，在我们之前的资助期间的研究表明，苯胺暴露于大鼠导致脾脏氧化应激，从活性铁，脂质过氧化，蛋白质氧化，DMA氧化，脂质衍生的谷胱甘肽-蛋白质加合物和硝基酪氨酸的增加中可以明显看出。这些变化伴随着转录因子NF-κ B和AP-1的激活，以及纤维化和炎性细胞因子的上调。形态学上，脾脏显示血管充血，由于窦状细胞和成纤维细胞增加导致红髓细胞结构增加，包膜增厚和纤维化。在确定了氧化应激在苯胺脾脏毒性中的重要作用后，我们现在将研究方向转向苯胺诱导的氧化应激途径，该途径导致脾脏纤维化和肿瘤发生。我们假设苯胺诱导的氧化应激，由于过量生产的氧化剂（ROS和RNS）激活氧化还原敏感的转录因子（NF-κ B和AP-1），导致转录的基因参与纤维化和细胞生长调节途径在脾脏。此外，对DNA的氧化损伤导致基因突变。这些事件单独或共同导致脾脏纤维化和/或肿瘤发生。本研究将通过以下三个具体目标来验证这一假设：目标1将阐明转录因子NF-κ B和AP-1在苯胺脾毒性中的调控、信号传导机制和相关基因表达。目的2将研究氧化性DNA损伤和修复，丙二醛-DNA加合物，DNA甲基化和肿瘤抑制基因p53突变在苯胺诱导的脾毒性中的作用。目的3将通过表征iNOS调节和硝化蛋白的形成，以及通过检查NO/ONOO在NF-κ B活化、细胞因子表达和DNA损伤的调节中的作用，来研究活性氮物质对脾损伤的贡献。这些研究将阐明苯胺诱导的脾毒性的机制，并将是重要的，在制定战略，以防止毒性，并在风险评估苯胺和其他结构相关的芳香胺。

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.