Corsini Emanuela, Viviani Barbara, Birindelli Sarah, Gilardi Federica, Torri Anna, Codecà Ilaria, Lucchi Laura, Bartesaghi Stefano, Galli Corrado L, Marinovich Marina, Colosio Claudio
Laboratory of Toxicology, Department of Pharmacological Sciences, University of Milan, Via Balzaretti 9, 20133 Milan, Italy.
Toxicol Appl Pharmacol. 2006 Apr 15;212(2):89-98. doi: 10.1016/j.taap.2005.07.002. Epub 2005 Aug 19.
Mancozeb, a polymeric complex of manganese ethylenebisdithiocarbamate with zinc salt, is widely used in agriculture as fungicide. Literature data indicate that ethylenebisdithiocarbamates (EBDTCs) may have immunomodulatory effects in humans. We have recently found in agricultural workers occupationally exposed to the fungicide mancozeb a statistically significant decrease in lipopolysaccharide (LPS)-induced tumor necrosis factor-alpha (TNF) production in leukocytes. TNF is an essential proinflammatory cytokine whose production is normally stimulated during an infection. The purpose of this work was to establish an in vitro model reflecting in vivo data and to characterize the molecular mechanism of action of mancozeb. The human promyelocytic cell line THP-1 was used as in vitro model to study the effects of mancozeb and its main metabolite ethylenthiourea (ETU) on LPS-induced TNF release. Mancozeb, but not ETU, at non-cytotoxic concentrations (1-100 microg/ml), induced a dose- and time-dependent inhibition of LPS-induced TNF release, reflecting in vivo data. The modulatory effect observed was not limited to mancozeb but also other EBDTCs, namely zineb and ziram, showed similar inhibitory effects. Mancozeb must be added before or simultaneously to LPS in order to observe the effect, indicating that it acts on early events triggered by LPS. It is known that nuclear factor-kappaB (NF-kappaB) tightly regulates TNF transcription. We could demonstrate that mancozeb, modulating LPS-induced reactive oxygen species generation, prevented IkappaB degradation and NF-kappaB nuclear translocation, which in turn resulted in decreased TNF production. To further understand the mechanism of the effect of mancozeb on TNF transcription, THP-1 cells were transfected with NF-kappaB promoter-luciferase construct, and the effect of mancozeb on luciferase activity was measured. Cells transfected with promoter constructs containing kappaB site showed decreased LPS-induced luciferase activity relative to control after mancozeb treatment, confirming NF-kappaB binding as an intracellular target of mancozeb. Overall, this study contributes to our understanding of the mechanism underlying mancozeb-induced immunotoxicity.
代森锰锌是一种锰代森乙撑双二硫代氨基甲酸盐与锌盐的聚合物络合物，在农业中广泛用作杀菌剂。文献数据表明，乙撑双二硫代氨基甲酸盐（EBDTCs）可能对人类具有免疫调节作用。我们最近发现，在职业性接触杀菌剂代森锰锌的农业工人中，白细胞中脂多糖（LPS）诱导的肿瘤坏死因子-α（TNF）产生有统计学意义的下降。TNF是一种重要的促炎细胞因子，其产生在感染期间通常会受到刺激。这项工作的目的是建立一个反映体内数据的体外模型，并表征代森锰锌的分子作用机制。人类早幼粒细胞系THP-1被用作体外模型，以研究代森锰锌及其主要代谢产物乙撑硫脲（ETU）对LPS诱导的TNF释放的影响。在非细胞毒性浓度（1-100微克/毫升）下，代森锰锌而非ETU诱导了LPS诱导的TNF释放的剂量和时间依赖性抑制，这反映了体内数据。观察到的调节作用不仅限于代森锰锌，其他EBDTCs，即代森锌和福美双，也显示出类似的抑制作用。代森锰锌必须在LPS之前或同时添加才能观察到效果，这表明它作用于LPS触发后的早期事件。已知核因子-κB（NF-κB）严格调节TNF转录。我们可以证明，代森锰锌通过调节LPS诱导的活性氧生成，阻止IκB降解和NF-κB核转位，进而导致TNF产生减少。为了进一步了解代森锰锌对TNF转录影响的机制，用NF-κB启动子-荧光素酶构建体转染THP-1细胞，并测量代森锰锌对荧光素酶活性 的影响。用含有κB位点的启动子构建体转染的细胞在代森锰锌处理后相对于对照显示出LPS诱导的荧光素酶活性降低，证实NF-κB结合是代森锰锌的细胞内靶点。总体而言，这项研究有助于我们理解代森锰锌诱导免疫毒性的潜在机制。
