基于原位代谢策略的大气细颗粒物重要组分致呼吸系统的毒效应及分子机制研究

Respiratory system is the main target of ambient fine particulate matter (PM2.5), it exists some extrahepatic cytochrome P450 enzymes (CYPs), which lead to be speculated that these specific CYP enzymes in the respiratory system could mediate the in situ metabolic activation of the important components in PM2.5, resulting in early and serious injuries. However, the role and mechanism are still ambiguous and elaborate investigation is urgently required. Based on our past several years’ accumulation and scientific advantage in the study on biotransformation of pollutants and human health hazard, in the present study, taking the respiratory CYP enzymes and their in situ metabolic activation as a breakthrough, we will systematically evaluate the respiratory damages and carcinogenicity by non-carcinogenic and carcinogenic components using specific cell models, animal models and populations. Moreover, we will still explore the potential mechanism on PM2.5-induced respiratory toxicity mediated by circRNA-miRNA-mRNA axis following the inflammatory pathways. As a result, the identification of the important toxic components of PM2.5, assessment of early human health risk, screening of key biomarkers including non-coding RNA, a series of new experimental models, and the establishment of the database of PM2.5 and human health will not only provide a new strategy on respiratory injuries evaluation and precise prevention of PM2.5, but also provide the scientific basis for health risk assessment and early warning of ambient fine particulate matter.

呼吸系统是大气细颗粒物（PM2.5）健康危害的主要靶部位，存在多种特异表达的肝外细胞色素P450酶（CYP），推测这些CYP酶可通过原位代谢活化PM2.5重要组分而导致呼吸系统早期严重的损伤，但未见相关研究。结合课题组多年来在环境污染物生物转化和PM2.5健康危害研究方面的积累和优势，本项目以呼吸系统CYP酶及原位代谢为切入点，利用特定细胞、动物和人群系统解析PM2.5中重要致癌和非致癌有机组分及其经代谢活化导致呼吸系统的急慢性损伤及致癌效应，深入研究circRNA-miRNA-mRNA轴调控炎症通路介导PM2.5致呼吸系统损伤的分子机制。PM2.5重要毒性组分甄别、早期健康危害评估、关键非编码RNA等生物标志筛选、系列实验模型、PM2.5和人群健康数据库的构建等，不仅可为PM2.5呼吸系统的危害评价及精准预防提供有效支撑，也可为PM2.5的健康风险评估和早期预警提供科学依据。

围绕课题研究内容，在PM2.5毒性组分及分布特征解析、呼吸系统CYP酶筛选及模型构建的基础上，从原位代谢角度系统阐明了PM2.5中重要毒性组分致呼吸系统损伤及分子机制，并对PAHs与CYP1A1的构效关系、混合毒性预测及风险评估进行了研究，已圆满完成各项任务，实现了预期目标。主要发现如下：①江苏PM2.5中PAHs呈现苏北、苏中、苏南依次减低趋势，冬季高于夏季，燃煤和汽车尾气是主要来源；除常见PAHs外，N21aP、BcP以及HMW-PAHs也较高；室内PM2.5以吸烟为主，5-HMF含量较高；②呼吸系统CYP酶主要以CYP1A1和CYP2A5为主，主要表达于上皮细胞、内皮细胞以及巨噬细胞，可能是关键作用靶点；③CYP1A1介导N21aP在肺泡II型上皮细胞的原位代谢，通过生成N21aP-二醇环氧产物促进肺纤维化发生发展；④DBfkT是从PM2.5中发现的新的HMW-PAHs，主要来源于燃煤，可被CYP1A1代谢生成环氧化产物导致肺损伤；⑤CYP2A5通过代谢5-HMF生成DFF从而损伤小鼠肺泡巨噬细胞-上皮屏障而导致肺炎性损伤；CYP2A5还可代谢BcP生成二醇环氧产物致小鼠肺部急慢性炎症；⑥hsa_circ_0041714/hsa_miR_3663-3p/ID3轴是CYP2A13代谢活化AFB1致肺上皮细胞恶性转化的重要机制，而外泌体miR487a/487b簇不仅促进了NSCLC发生发展，也可能成为潜在的诊断指标；⑦vdW是CYP1A1代谢活化PAHs最关键因素，基于CYP酶的Compound I结合构象可更客观地预测PAHs的联合致突变风险。研究结果为系统阐明PM2.5致呼吸系统损伤及其机制提供新的理论依据，为环境PM2.5中多种毒性组分的健康风险评估提供了新的策略，也为基于CYP酶代谢减毒的健康危害干预和防治提供了新的思路，具有重要的学术价值和良好的运用前景。