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苯、甲苯、二甲苯等芳烃是重要的工业原料和挥发性溶剂[1-2],其具有强的血液毒性和致癌作用,均被列入美国EPA 的129 种优先污染物名单[3]. 美国职业苯暴露量为16 mg·m−3[4],而在发展中国家,职业性苯暴露量比美国还要高1—2个数量级[4-6]. 为此,许多研究人员进行了苯及苯系物暴露人群的代谢组学[7] 研究,并通过代谢组学软件筛选出内源性生物标志物与相应的代谢路径,这对于疾病诊断与监测、生物标志物鉴定和毒性机制探索等都能起到非常重要的作用[8-16]. 如:Sun [17-18]与Campo等[19]近几年开展了对苯及苯系物暴露的代谢组学研究. 已报道的苯及苯系物暴露的代谢组学方法是基于代谢物的非手性总量定性与定量分析,但对代谢产物的手性分析领域并没有涉及到. 代谢产物的手性分析在医学领域有重要的应用,如Kimura等[20]报道了手性氨基酸代谢物用于慢性肾炎诊断的新型的生物标志物监测. L-型氨基酸的异构体即D-型氨基酸越来越多地被认为是新型的生物标志物. 这项研究测试了多种手性氨基酸是否与肾功能、并发症以及慢性肾炎(CKD)的诊断有关并确认了手性氨基酸可作为肾炎疾病中的潜在生物标志物. 而人类机体的组成部分及其代谢产物一般也都具有手性[21-22]. 多糖和核酸中的糖是右旋的D-构型;除某些细菌以外,蛋白质都是由左旋的L-氨基酸组成;在机体的代谢过程中的细胞表面的受体和生物酶,一般也都具有手性. 当它们与环境中污染物相互作用时,通常要经过复杂的手性生物代谢过程[23-24]. 因此,从立体化学的角度研究代谢物的手性和含量变化对于深入评价污染物的药物功能和毒理学具有重要意义[25]. 将代谢组学技术与手性毒理学分析结合在疾病的病理、药理及食品、环境安全等领域的应用文献报道较少[26-33],在职业卫生领域的研究尚未见报道.
本研究借助自制的手性固定相,通过代谢组学技术和统计学软件筛查出职业场所苯及苯系物暴露人群尿液中有差异性的靶向手性代谢产物及相应的代谢途径,这对于揭示其体内代谢机理,评价职业场所相关从业人员的职业危害,以及职业卫生管理部门加强行业监管、职业性防护干预等都具有重要的现实意义.
苯及苯系物暴露人群尿液的靶向代谢组学手性分析
Targeted metabolomics chirality analysis of human urine exposed to benzene and benzene series
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摘要: “三苯”具有强的人体血液毒性和致癌作用,是一类重要的环境污染物. 以往常通过代谢组学软件筛查出工作场所中苯及苯系物暴露人群的内源性代谢物与相应的代谢路径,而未考虑机体的立体化学作用对代谢的影响. 基于自制的手性固定相,优化色谱分离与尿样的前处理条件后,借助开放平台MetaboAnalyst 5.0 软件结合多元统计分析,分析出有显著差异的代谢物和代谢通路的变化. 暴露组检测到5种内源性的代谢物即泛酸、酮戊二酸、D-苯丙氨酸、2-羟基-戊二酸、焦谷氨酸与2种外源性的代谢物即D-苯巯基尿酸与D-苄巯基尿酸. 6组代谢通路受到显著影响,包括D-谷氨酰胺和 D-谷氨酸代谢、谷胱甘肽代谢、丁酸代谢、丙氨酸、天冬氨酸和谷氨酸代谢、柠檬酸循环和嘌呤代谢. 结果表明,苯及苯系物暴露人群尿液代谢产物中2-羟基-戊二酸、焦谷氨酸及D-苯丙氨酸会引起明显的升高,苯巯基尿酸与苄巯基尿酸也可能发生由L-型向D-型的手性转化,这为进一步研究苯及苯系物引起血液毒性的潜在机制奠定了基础,也为全面评估苯及苯系物暴露人群的健康风险提供了科学依据.Abstract: "Triphenyl" has strong human blood toxicity and carcinogenic effects, which is an important environmental pollutants. As usual, metabolomics software was used to screen the endogenous metabolites and corresponding metabolic pathways of benzene and benzene series exposed people in the workplace, without considering the influence of stereochemistry on metabolism. Based on the home-made chiral stationary phase, after optimizing the chromatographic separation and pretreatment conditions of urine samples, the open platform MetaboAnalyst 5.0 software being combined with multivariate statistical analysis was used to analyze the changes of significantly different metabolites and metabolic pathways. Five endogenous metabolites (pantothenate, oxoglutarate, D-phenylalanine, 2-hydroxy-gluarate, pyroglutamic acid) and two exogenous metabolites (D-phenylmercapturic acid and D-benzylmercapturic acid) were detected in the exposed group. Six groups of metabolic pathways were significantly affected, including D-glutamine and D-glutamate metabolism, Glutathione metabolism, Butanoate metabolism, Alanine, aspartate and glutamate metabolism, Citrate cycle (TCA cycle) and Purine metabolism. Results show that 2-hydroxy-glutaric acid, glutamate and D-phenylalanine can cause obvious rise in human urine metabolites exposed to benzene and benzene series, the configurational transformation may also occur from L-type of D-type for phenylmercapturic acid and benzylmercapturic acid, which laid a foundation for further research on the potential mechanism of blood toxicity caused by benzene and benzene series, and also provides a scientific basis for comprehensive assessment of the health risk of benzene and benzene series exposed population.
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Key words:
- workplace /
- benzene and benzene series /
- human urine /
- targeted metabolomics /
- chiral analysis.
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表 1 不同组的相应参数表(n=30)
Table 1. Corresponding parameter table for different groups (n=30)
对照组
Control group暴露组
Exposure group行政人员 油漆工 * 年龄
Age31.93±8.93 31.60±7.61 性别
Gender男 19 21 女 11 9 吸烟
Smoke是 0 2 否 30 28 饮酒
Drink wine是 10 6 否 20 24 遗传病史
Whether there is a history of genetic disease是 0 0 否 30 30 暴露强度/(mg m−3)
Exposure intensity苯 — — 甲苯 — 4.94±0.0094 邻-二甲苯 — 0.99±0.013 间-二甲苯 — 1.44±0.036 对-二甲苯 — — 工作年限/a
Length of service8.43±7.05 7.80±6.90 *与对照组比较,P<0.05.吸烟:指吸烟超过1 d,烟龄超过1 a.饮酒:指饮酒超过1年至少1周1次. — 代表没有检出.
*Compared with the control group, P<0.05. Smoking: refers to smoking for more than 1 day and smoking for more than 1 year. Drinking: refers to drinking for more than 1 year at least once a week. — means no detection.表 2 PMA, BMA, d2-PMA, MHBMA-1+-2 与 DHBMA的多反应监测优化条件
Table 2. MRM optimization conditions for PMA, BMA, d2-PMA, MHBMA-1+-2 and DHBMA
化合物
Compounds母离子
Precusor
(m/z)子离子
Product
(m/z)驻留时间/
ms
Dwell time解簇电压/
eV
DP碰撞能量/
eV
CE(1) 苯巯基尿酸 (PMA)* 238.03 108.94 30 −16.91 −16.99 (2) 苄巯基尿酸 (BMA)* 252.07 122.99 30 −32.15 −24.22 (3) 同位素标记的苯巯基尿酸内标 (d2-PMA)* 241.10 109.93 30 −16.84 −17.14 (4) N-乙酰基-S-(1-羟基甲基-2-丙烯基)-L-半胱氨酸+N-乙酰基-S-(2-羟基-3-丁烯基)-L-半胱氨酸(MHBMA-1+-2)* 232.03 102.94 30 −19.90 −14.14 (5) N-乙酰基-S-(1-羟基甲基-2-丙烯基)-L-半胱氨酸+N-乙酰基-S-(2-羟基-3-丁烯基)-L-半胱氨酸(MHBMA-1+-2) 232.03 128.10 30 −33.14 −14.16 (6) N-乙酰基-S-(3,4-二羟基丁基-L-半胱氨酸) (DHBMA)* 250.05 120.95 30 −11.97 −18.96 (7) N-乙酰基-S-(3,4-二羟基丁基-L-半胱氨酸 )(DHBMA) 250.05 127.80 30 −14.00 −16.26 (8) 泛酸 Pantothenate 218.01 146.13 30 −25.00 −21.00 (9) 酮戊二酸 Oxoglutarate 145.10 101.12 30 −35.31 −13.00 (10) D-苯丙氨酸 D-phenylalanine 166.1 103.20 30 −16.93 −30.46 (11) 2-羟基-戊二酸 2-hydroxygluarate 147.12 128.74 30 −45.52 −17.12 (12) 焦谷氨酸 Pyroglutamic acid 128.08 82.13 30 −23.16 −19.15 *代表定量离子. *Represent quantitative ion. 表 3 尿液鉴定出的差异性代谢物
Table 3. Differential metabolites identified in urine
序号
NO.趋势(暴露组/对照组)
Tendency(exposure/control)代谢物
Metabolities相关路径
Related pathway1 ↑ D-苯巯基尿酸
D-PMA谷胱甘肽代谢 2 ↑ D-苄巯基尿酸
D-BMA谷胱甘肽代谢 3 — 泛酸Pantothenate 丙氨酸、天冬氨酸和谷氨酸代谢 4 ↓ 酮戊二酸Oxoglutarate D-谷氨酰胺和 D-谷氨酸代谢 5 ↑ D-苯丙氨酸
D-phenylalanine丙氨酸、天冬氨酸和谷氨酸代谢,柠檬酸循环 6 ↑ 2-羟基-戊二酸
2-hydroxy-gluarate柠檬酸循环 7 ↑ 焦谷氨酸
Pyroglutamic acidD-谷氨酰胺和 D-谷氨酸代谢,谷胱甘肽代谢 注:↑代表上调,↓代表下调,—代表不变.
Note:↑represent upward adjustment, ↓represent downward adjustment, and — represent unchanged.表 4 代谢路径P值表
Table 4. Metabolic pathway P values
路径名
Pathway NameP −lgP D-谷氨酰胺和 D-谷氨酸代谢
D-Glutamine and D-glutamate metabolism0.002683 2.57130 丁酸代谢
Butanoate metabolism0.006593 2.1578 柠檬酸循环
Citrate cycle (TCA cycle)0.008706 2.06020 谷胱甘肽代谢
Glutathione metabolism0.012002 1.92075 丙氨酸、天冬氨酸和谷氨酸代谢
Alanine, aspartate and glutamate metabolism0.012006 1.92060 嘌呤代谢
Purine metabolism0.025953 1.58620 -
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