應用質譜儀為基礎的脂質體學探討全氟碳化物及鄰苯二甲酸酯類之環境暴露對孩童血液脂質之影響

Abstract

全氟碳化物 (perfluoroalkyl substances, PFASs) 與鄰苯二甲酸酯類 (phthalates) 兩類化學物質皆經常應用於工業用品及消費產品中，並可在人體樣本中被廣泛偵測到。近年來，許多流行病學研究探討 PFASs 和 phthalates 的暴露是否會對人體造成何種影響，但此類研究並未能針對這類化學物質以及所造成的可能不良健康效應之間提供完善且清楚的相關性。此外，不少動物實驗發現 PFASs 和 phthalates 會干擾生物體之內分泌系統，並可能因而造成體內脂質代謝調節與脂肪酸儲存之改變。因此，本研究的目的是利用脂質體學來探討兒童暴露到環境中的 PFASs 和 phthalates 後，其體內所可能產生的機制改變，並回推可能與暴露相關的不良健康效應為何。 本研究納入共290台灣孩童進行研究，使用高效能液相層析串聯質譜儀分析孩童血液中的 13 種 PFASs 與尿液中的 12 種 phthalates 代謝物之濃度，並應用極致效能液相層析串聯質譜儀結合多變量分析和多元線性迴歸模型去了解孩童暴露到不同濃度的 PFASs 與 phthalates 時，其血清內磷脂醯膽鹼 (phosphatidylcholines) 及 神經磷脂 (sphingomyelins) 的變化趨勢，並利用相關之問卷資料納入統計以闡明血清內脂質改變與化學暴露物質的不同濃度之可能關聯。 研究結果顯示，孩童暴露到不同濃度之 PFOS (perfluoro-n-octyl sulfonate) PFTrDA (perfluoro-n-tridecanoic acid)、PFDA (perfluoro-n-decanoic acid) 以及 DEHP (di(2-ethylhexyl) phthalate) 之代謝物－MEHHP (mono(2-ethyl-5-hydroxyhexyl) phthalate)，會使其血清內相同次分類之磷脂醯膽鹼和神經磷脂有相似的變化趨勢，並且也可觀察到孩童血清脂質體之變化會與其性別、身體質量指數以及居住地有關。其中，雙醯磷脂醯膽鹼 (diacyl-phosphatidylcholine) 之下降以及神經磷脂與縮醛磷脂 (plasmalogen) 的上升會和 PFASs 之暴露有關，顯示暴露可能對肝臟功能、極低密度脂蛋白之合成和分泌、胰島素抗性，以及細胞膜調節造成影響；另外，雙醯磷脂醯膽鹼與溶血磷脂醯膽鹼 (lyso-phosphatidylcholine) 的上升以及神經磷脂與縮醛磷脂的下降會和孩童體內MEHHP量之多寡有關，顯示暴露到 DEHP 可能與極低密度脂蛋白分泌異常、系統性發炎反應、體內之抗氧化機制調節以及神經性危害有所連結。 如上述所提，不同次分類之磷脂醯膽鹼和神經磷脂的改變可能會與數種 PFASs 以及 phthalates 暴露相關，並可依其回推至孩童體內可能的機制改變以及不良健康效應。此研究結果可支持脂質體學是一個有效的方法用以探討暴露與可能健康效應之相關性，並可提供後續研究者進一步的研究方向。

Perfluoroalkyl substances (PFASs) and phthalates are two groups of chemicals which are commonly used in man-made products, thus can be detected in human samples generally. The recent epidemiologic surveys which focus on these chemicals still cannot provide strong association between exposure of those compounds and the adverse health effects and suggest possible mechanisms. Numerous animal studies showed that PFASs and phthalates disrupt the endocrine system and might influence the regulation of lipid metabolism and fatty acid storage. Since lipids are possible target molecules of PFASs and phthalates, the aims of this study are to identify changes of critical lipids caused by those chemical exposure and to understand possible biological impacts. 290 Taiwanese children exposed to environmental PFASs and phthalates were included. Thirteen PFASs and twelve phthalate metabolites were analyzed in their biofluids by high-performance liquid chromatography tandem mass-spectrometry. Two major lipid groups, phosphatidylcholine (PCs) and sphingomyelin (SMs), in the serum samples were analyzed by ultra-performance liquid chromatography tandem mass-spectrometry followed by multivariate statistical analysis to examine the differences of serum lipdome in children exposed to different levels of PFASs and phthalates. The results showed children exposed to different levels of PFOS (perfluoro-n-octyl sulfonate), PFTrDA (perfluoro-n-tridecanoic acid), PFDA (perfluoro-n-decanoic acid) and MEHHP (mono(2-ethyl-5-hydroxyhexyl) phthalate) had distinct serum lipidomes. The lipidomes of children’s serum were also associated with their genders, body mass indexes and residential regions. Declined diacyl-PCs as well as elevated plasmalogens and SMs were related to PFAS levels, which may demonstrate the possible effects on liver dysfuntion, lipoprotein metabolism, insulin resistance and PFASs-membrane interaction. Increased diacyl-PCs and lyso-PCs, as well as decreased plasmalogens and SMs were correlated with MEHHP exposure, which may be associated with VLDL secretion, pro-inflammatory effects, antioxidant response and possible neurotoxicity. In conclusion, different subclasses of phosphorylcholine-containing lipids were found to be associated with PFAS and phthalate exposures, representing possible mechanisms and potential adverse effects on children. This study demonstrated MS-based lipidomic approaches are powerful tool to realize lipid perturbation caused by background levels of PFASs and phthalates in children and to suggest their possible adverse health effects.