低浓度大气颗粒物短期暴露对小鼠肺组织损伤效应研究

Effects of short-term exposure to ambient PM on pulmonary tissue in mice

目的建立低浓度大气颗粒物(PM)短期暴露小鼠模型,探讨低浓度大气PM短期暴露对小鼠肺组织的影响。方法 20只6周龄BALB/c小鼠随机分为PM暴露组和阴性对照组,PM暴露组暴露于未过滤空气,阴性对照组暴露于经高效空气过滤器过滤的空气,每天暴露24 h,持续2周。观察小鼠体重等指标变化,计数支气管肺泡灌洗液(BALF)细胞并分类,采用苏木精-伊红(HE)染色法观察肺部病理学形态变化,荧光定量PCR法检测肺组织细胞色素P450 1A1(CYP1A1)和O6-甲基鸟嘌呤-DNA甲基转移酶(MGMT)m RNA的表达。结果 PM暴露组平均PM2.5浓度为(99.7±51.6)μg/m3。协方差分析结果显示,两组小鼠体重增重差异无统计学意义(P>0.05);与阴性对照组比较,PM暴露组小鼠BALF中巨噬细胞数量增加(P<0.01),但两组粒细胞数和淋巴细胞数差异均无统计学意义(P>0.05);PM暴露组小鼠肺组织病变率为50.0%,高于阴性对照组的0.0%(P=0.033);PM暴露组小鼠肺组织CYP1A1和MGMT m RNA表达量均高于阴性对照组(P<0.05)。结论低浓度PM短期暴露可诱导小鼠肺组织发生炎症反应,上调CYP1A1和MGMT基因表达,对小鼠肺组织产生毒性效应。

Objective To establish a mouse model for short-term exposure to ambient PM and to investigate the impact on the Cytochrome P4501A1(CYP1A1)and O6-methylguanine-DNA methyltransferase(MGMT)mRNA expression.Methods Twenty6-week-old BALB/c mice were randomly assigned to one of two groups,each consisting of5male and5female animals.These mice were then housed in situ concurrently for2weeks in our lab located in urban area of Hangzhou.The first group was kept inside an individual ventilated caging(IVC)system equipped with a high-efficiency particulate-air(HEPA)filter,whereas the second was housed inside a IVC with HEPA filter removed.Then it's allowed flow-through of ambient air freely via a pipeline outside.Mice inside the HEPA filtration chamber were therefore protected from exposure to all airborne particulate.The other was in fact exposed to ambient air directly.After the exposure,the bronchoalveolar lavage(BAL)fiuid was collected for each animal and the differentials and percentages of BAL cells were determined.Paraffin sections of lungs of the mice were made and were examined for any inflammation changes.CYP1A1and MGMT mRNA levels in the lungs were then detected by RT-qPCR.Results The mean concentration of PM2.5was(99.7±51.6)滋g/m3in the exposure group.Weight increases were similar between the two groups(P>0.05).The number of total cells and macrophages in BALF from exposure mice was significantly greater than control.A mild inflammation was observed from light photomicrographs of the lung after PM exposure.CYP1A1and MGMT mRNA levels were significantly up-regulated in the lung from the exposure group.Conclusion A mouse model for short-term exposure to ambient PM was established.CYP1A1and MGMT may mediate the toxic effect of PM exposure.