產前全氟碳化物暴露對於組蛋白修飾及兒童行為發展間之相關性探討

Abstract

背景及目的：全氟碳化物會穿透胎盤，可能造成兒童產前暴露之危害，尤其是在懷孕期間暴露全氟辛烷磺酸和全氟辛酸，可能會對兒童的發展造成不良健康影響，而此影響可能不是經由基因損害而導致，可能是由一個潛在的表基因機制所調控。組蛋白修飾會影響染色質的結構，與基因體的不穩定性和轉錄活性有關。產前全氟碳化物的暴露可能會改變表基因機制，因此本研究的目的為探討產前全氟碳化物的暴露與組蛋白修飾、兒童行為發展之相關性。 材料與方法：本研究採用2004年到2005年間所收集的臺灣出生長期追蹤世代研究，經過篩選後一共有91對母嬰配對納入研究，並完成長期追蹤、暴露測量以及樣本收集。臍帶血中的全氟辛酸、全氟辛烷磺酸、全氟癸酸和全氟壬酸的濃度是使用超高效液相層析串聯質譜法分析。兩歲兒童的行為發展則是利用一歲半至五歲的兒童行為檢核表所量測，並且利用西方墨點法分析兩歲兒童的組蛋白修飾H3K4me3, H3K27me3與H3K9me3之程度。本研究使用單一與多重線性回歸校正相關干擾因子之後進行全氟碳化物、組蛋白修飾與兩歲兒童行為發展之關聯性探討。 結果：只有自然對數轉換後的全氟癸酸與兒童情緒反應有顯著相關 [ß值 (95% 信賴區間)= -0.45 (-0.89, -0.01), p=0.04]。在校正相關干擾因子後，全氟碳化物與兩歲兒童行為之發展沒有顯著的線性相關，但是具有性別差異。在男孩中，全氟辛酸與兒童情緒反應 [adjusted ß (95% CI)= 1.47 (0.22, 2.71), p=0.02] 及焦慮/沮喪問題 [adjusted ß (95% CI)= 1.70 (0.36, 3.04), p=0.02] 有顯著相關；全氟癸酸與注意力問題有顯著相關 [adjusted ß (95% CI)= 0.52 (0.10. 0.93), p=0.02]。而在女孩中，全氟辛酸與退縮行為達到統計上顯著相關 [adjusted ß (95% CI)= 1.03 (0.05, 2.01), p=0.02]。全氟辛酸的濃度會影響組蛋白修飾H3K27me3 的程度，且達統計顯著相關[adjusted ß (95% CI)= -1.73(-3.31, -0.15), p=0.03]。全氟辛酸濃度最高組與參考組相比，會造成組蛋白修飾H3K27me3 [多重校正之ß值(95%信賴區間)= -4.38 (-7.93, -0.84)] 與H3K9me3 [-2.40 (-4.37, -0.43)] 的程度顯著降低。組蛋白修飾與兒童行為之發展則無統計上顯著相關。 結論：產前全氟碳化物的暴露可能會影響兒童行為發展且具有性別差異。產前全氟碳化物的暴露會造成組蛋白修飾的程度降低，表示全氟碳化物可能會誘發表基因遺傳的變化和潛在影響疾病的結果。但是需要更進一步的研究來證實這些發現。

Background: Perfluoroalkyl substances (PFASs) can penetrate placenta and make prenatal exposure of potential concern. Perfluorooctyl sulfonate (PFOS) and perfluorooctanoic acid (PFOA) exposures, especially during pregnancy, were associated with adverse childhood development without DNA damage, suggesting a potential epigenetic regulation. Histone modifications affect chromatin configuration and are associated with genomic instability and transcription activities. Life-long effects of in utero PFASs exposures may be mediated via epigenetic changes. The aim of the study was to investigate the associations among in utero exposures to PFASs, histone modifications and children's behavior. Methods: The study was a follow-up study from the Taiwan Birth Panel Study (TBPS), including children born between July 2004 and June 2005 in four hospitals in Taipei city and county. A total of 91 mother-infant pairs completed follow-up information, exposure measurements and sample collection. Cord blood plasma PFOA, PFOS, perfluorononanoic acid (PFNA) and perfluoroundecanoic acid (PFUA) were analyzed by ultraperformance liquid chromatography-tandem mass spectrometry (UPCL-MS/MS). Children’s behavior problems at 2 years of age were measured by the child behavior checklist for ages 1.5-5 (CBCL/1.5-5). Global histone H3 at lysine 4 residue trimethylation (H3K4me3), histone H3 at lysine 27 residue trimethylation (H3K27me3) and histone H3 at lysine 9 residue trimethylation (H3K9me3) levels were measured from blood leukocytes of 2-year-old children. Simple and multiple regression models adjusting for potential confounders were used to investigate the relationships among PFASs, histone modifications and behavior outcomes. Results: Only prenatal PFUA concentrations in natural log transformed were correlated with emotionally reactive [ß (95% CI)= -0.45 (-0.89, -0.01), p=0.04]. After adjusting for potential confounders, no statistical linear association was shown between PFASs and child behavior problems, but had sex-specific patterns. Among boys, PFOA is associated with emotionally reactive problems [adjusted ß (95% CI)= 1.47 (0.22, 2.71), p=0.02] and anxious/depressed problems [adjusted ß (95% CI)= 1.70 (0.36, 3.04), p=0.02]; PFNA is associated with attention problems [adjusted ß (95% CI)= 0.52 (0.10. 0.93), p=0.02]. Among girls, lnPFOA is correlated with withdrawn problems [adjusted ß (95% CI)= 1.03 (0.05, 2.01), p=0.02]. Global H3K27me3 was correlated with lnPFOA [adjusted ß (95% CI)= -1.73(-3.31, -0.15), p=0.03]. The highest PFOA levels are associated with global H3K27me3 [adjusted ß (95% CI)= -4.38 (-7.93, -0.84)] and H3K9me3 [-2.40 (-4.37, -0.43)] levels comparing to the lowest group. No association was observed between global histone modification levels and children's behavior problems. Conclusion: These data suggest that prenatal PFASs exposure might be associated with children's behavior problems of the CBCL at age 2 and have a sex-specific pattern. Prenatal exposures to PFASs were associated with decreased global histone modification levels, suggesting that PFASs may induce epigenetic changes and potentially influence disease outcomes later in life. Further studies are needed to confirm these findings.