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脾毒性的机制，并制定预防和治疗策略。使用苯胺作为原型化合物，我们之前资助的研究表明，大鼠暴露于苯胺会导致脾脏氧化应激，从活性铁、脂质过氧化、蛋白质氧化、DMA氧化、脂质衍生的醛蛋白加合物和硝基酪氨酸的增加中可以看出。这些变化伴随着转录因子NF-kappaB和AP-1的激活，以及纤维化和炎症细胞因子的上调。形态学上，脾脏血管充血，因窦状细胞和成纤维细胞增多而红髓细胞增多，包膜增厚和纤维化。在确定了氧化应激在苯胺脾毒性中的重要作用后，我们现在将把我们的研究方向转向苯胺诱导的氧化应激途径，导致脾纤维化和肿瘤发生。我们假设苯胺诱导的氧化应激是由于氧化剂（ROS和RNS）的过度产生而激活氧化还原敏感的转录因子（NF-kappaB和AP-1），导致参与脾脏纤维化和细胞生长调节途径的基因转录。此外，DNA的氧化损伤会导致基因突变。这些事件单独或共同导致脾脏纤维化和/或肿瘤发生。这一假设将通过追求三个特定目的来验证：目的1将阐明转录因子NF-kappaB和AP-1的调控，信号机制和相关基因表达在苯胺脾毒性中的作用。目的2将研究氧化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突变在苯胺诱导脾毒性中的作用。目的3将通过表征iNOS的调控和硝化蛋白的形成，并通过检测NO/ONOO在调节NF-kappaB激活、细胞因子表达和DNA损伤中的作用，研究活性氮对脾损伤的贡献。这些研究将阐明苯胺诱发脾毒性的机制，对制定预防策略以及苯胺和其他结构相关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.