LIPID METABOLISM AND PHTHALATE TOXICITY INTERACTIONS

在令人兴奋的新研究中，我们证明了邻苯二甲酸酯和脂质 降血压药物(如邻苯二甲酸二乙基己酯和WY-14,643) 驻留肝巨噬细胞激活吞噬功能 细胞。此外，在体内，增加的细胞增殖被阻止 都是抗肿瘤坏死因子α和棕榈酸甲酯的抗体，棕榈酸甲酯是一种 库普弗细胞。根据这一新信息，我们假设 邻苯二甲酸盐激活枯否细胞产生促有丝分裂的细胞因子 刺激细胞增殖并导致肿瘤。为了检验这一假设， 将提出三个问题。首先，库普弗细胞是否负责 增塑剂能促进细胞增殖吗？库普弗细胞将 用DEHP和降脂药物WY-14,643体外或 从体内处理和培养的大鼠中分离出来。条件媒体来自 库普弗细胞将被添加到培养的肝细胞和细胞中 将对核扩散进行评估。类似的实验将会进行。 人的巨噬细胞和肝细胞，因为无论这些 化学物质会导致人类癌症仍然存在争议。尼莫地平， 棕榈酸甲酯和膳食甘氨酸将用于预防或减少 激活Kupffer细胞。我们希望这些实验能证明 结论：库普弗细胞产生的肿瘤坏死因子α是导致 增塑剂促进细胞增殖。第二，实验 以了解邻苯二甲酸盐如何激活库普弗细胞 以产生有丝分裂原。我们建议邻苯二甲酸盐将进入库普弗 细胞膜基于其亲脂性，增加细胞内 钙，并通过改变第二信使系统激活PKC。 相应地，不同脂溶性放射性标记药物的摄取 将会被比较。此外，邻苯二甲酸酯在体内的治疗效果 细胞内钙和蛋白激酶C将在分离的Kupffer中被测量 细胞。确定PKC是否激活NADPH氧化酶并增加 核因子/kappa/B介导的肿瘤坏死因子α的产生、超氧化物和核因子/kappa/B将 监测肿瘤坏死因子α基因表达的变化，并与之相关。第三，可以 邻苯二甲酸盐刺激细胞增殖和肿瘤的增加 在体内通过调节库普弗细胞来预防？饮食甘氨酸， 它抑制库普弗细胞的激活，将被用来阻止细胞 细胞增殖、细胞凋亡变化与癌前病变的形成 病灶和肿瘤，这是“黄金标准”。通过追求这些新的 假设，我们将填补我们知识中的重要空白 机械装置。这项工作的另一个重要影响将是提供 拥有机械性信息的政府监管机构将允许 他们将重点从这些化学物质引起的 过氧酶体和关注细胞增殖。

In exciting new studies, we showed that phthalic acid esters and lipid lowering drugs (e.g., diethylhexylphthalate (DEHP) and WY-14,643) activate phagocytosis by the resident hepatic macrophages, Kupffer cells. Further, increased cell proliferation was blocked in vivo by both an antibody to TNFalpha and methyl palmitate, an inactivator of Kupffer cells. Based on this new information, we hypothesize that phthalates activate Kupffer cells to produce mitogenic cytokines that stimulate cell proliferation and cause tumors. To test this hypothesis, three questions will be posed. First, are Kupffer cells responsible for increased cell proliferation due to plasticizers? Kupffer cells will be treated with DEHP and the lipid lowering drug WY-14,643 in vitro or isolated from rats treated in vivo and cultured. Conditioned media from Kupffer cells will be added to cultured hepatocytes and cell proliferation will be assessed. Similar experiments will be performed with human macrophages and hepatocytes since whether or not these chemicals cause cancer in humans remains controversial. Nimodipine, methyl palmitate and dietary glycine will be used to prevent or minimize activation of Kupffer cells. We expect these experiments to demonstrate conclusively that TNFalpha produced by Kupffer cells is responsible for enhanced cell proliferation caused by plasticizers. Second, experiments will be performed to understand how phthalates activate Kupffer cells to produce mitogens. We propose that phthalates will enter Kupffer cells membranes based on their lipophilicity, increase intracellular calcium, and activate PKC by altering second messenger systems. Accordingly, uptake of radiolabelled drugs of different lipid solubility will be compared. Further, the effect of phthalate treatment in vivo on intracellular calcium and PKC will be measured in isolated Kupffer cells. To determine if PKC activates NADPH oxidase and increases NF/kappa/B-mediated TNFalpha production, superoxide and NF/kappa/B will be monitored and correlated with changes in TNFalpha mRNA. Third, can phthalate-stimulated increases in cell proliferation and tumors be prevented in vivo by modulation of Kupffer cells? Dietary glycine, which inhibits Kupffer cell activation, will be used to prevent cell proliferation, changes in apoptosis, and the formation of preneoplastic foci and tumors, which is the "gold-standard." By pursuing these new hypotheses, we will fill important gaps in our knowledge regarding mechanisms. Another important impact of this work will be to provide governmental regulators with mechanistic information which will allow them to shift emphasis away from the fact that these chemicals induce peroxisomes and focus on cell proliferation.