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锌离子在PM2.5致小鼠肺部炎症中的作用

Effects of zinc ions on PM2.5-induced lung inflammation in mice

    摘要
  • 摘要:
    背景 细颗粒物（PM2.5）是大气污染物的主要成分之一，也是近年来我国雾霾污染的首要成因，可以对人体造成潜在的健康危害；锌是PM2.5中重要的重金属组分之一，但其是否参与PM2.5诱发的肺毒性和致病机制尚不清楚。
    目的 研究PM2.5及外源性锌离子对小鼠肺部炎症损伤的作用。
    方法 采集2015年11月至2016年3月新乡市大气PM2.5样品，将24只6~8周龄BALB/c雄性小鼠随机分为PBS对照组、PM2.5组、低浓度ZnSO4组和高浓度ZnSO4组，低浓度ZnSO4组锌离子浓度（30 μg·kg-1）与PM2.5样品中锌离子相同，高浓度ZnSO4组锌离子浓度（60 μg·kg-1）是PM2.5样品中锌离子的2倍，每组6只。采用气管滴注方式染毒，隔日染毒，共计3次。末次染毒次日处死小鼠，苏木精-伊红（HE）染色观察肺脏组织病理变化情况和炎性细胞浸润水平；流式细胞术检测肺泡灌洗液（BALF）中总细胞数量；BCA蛋白测定试剂盒和乳酸脱氢酶（LDH）检测试剂盒分别测定肺泡灌洗液中总蛋白含量和LDH含量；ELISA法检测肺泡灌洗液中白介素（IL）-1β蛋白水平。
    结果 与对照组相比，PM2.5组、低浓度ZnSO4组和高浓度ZnSO4组小鼠肺部出现明显炎性细胞浸润，肺泡壁断裂融合，肺部正常生理结构破坏。与对照组（14.78±2.82）×104个·mL-1相比，PM2.5组、低浓度ZnSO4组和高浓度ZnSO4组（24.11±5.30）×104、（24.00±4.61）×104、（24.00±4.61）×104个·mL-1BALF中总细胞数量明显升高（P < 0.05），但各染毒组间没有差异。与对照组（1.40±0.14）g·L-1相比，PM2.5组、低浓度ZnSO4组和高浓度ZnSO4组BALF中总蛋白浓度明显升高（2.58±0.50）、（2.69±0.41）、（3.62±0.98）g·L-1（P < 0.05），并且高浓度ZnSO4组较PM2.5组升高更为明显（P < 0.05）。与对照组（44.18±11.54）U·L-1相比，PM2.5组、低浓度ZnSO4组和高浓度ZnSO4组BALF中LDH水平升高（443.02±123.33）、（185.16±64.00）、（428.37±70.71）U·L-1（P < 0.05），并且PM2.5组和高浓度ZnSO4组升高更明显。与对照组（9.54±2.38）×103 ng·L-1相比，PM2.5组、低浓度ZnSO4组和高浓度ZnSO4组（20.51±3.04）×103、（15.98±0.53）×103、（26.36±4.87）×103 ng·L-1BALF中IL-1β水平明显升高（P < 0.05），并且相较于另外2组，高浓度ZnSO4组升高更明显（P < 0.05）。
    结论 锌离子可能是PM2.5诱导小鼠肺部炎症损伤的原因之一。

     

    Abstract:
    Background Fine particulate matter (PM2.5) is one of the main components of air pollutants which contribute to haze pollution in China in recent years. PM2.5 exposure can cause potential health hazards to human beings. Zinc is one of the important heavy metal components of PM2.5, but whether it is involved in PM2.5-induced lung toxicity and its pathogenic mechanism remain unclear.
    Objective The study investigates the effects of PM2.5 and exogenous zinc ions on the lung inflammation in mice.
    Methods PM2.5 samples were collected from Xinxiang City from November 2015 to March 2016. Twenty-four BALB/c male mice aged 6-8 weeks were randomly divided into a PBS control group, a PM2.5 group, a low ZnSO4 group (30 μg·kg-1, same with the zinc ion concentration of the PM2.5 samples), and a high ZnSO4 group (60μg·kg-1, two times the zinc ion concentration of the PM2.5 samples), with six mice in each group. Intratracheal instillation was administered once the other day, and for three times in total. The mice were sacrificed on the second day after the last exposure. Pathological changes of lung tissues and infiltration of inflammatory cells were observed by HE staining. The number of inflammatory cells in bronchoalveolar lavage fluid (BALF) was detected by flow cytometry. The total protein and lactic acid dehydrogenase (LDH) levels in BALF were determined with BCA protein assay kit and LDH assay kit respectively. The expression level of interleukin (IL)-1β protein was examined by ELISA.
    Results Compared with the control group, the PM2.5 group, low ZnSO4 group, and high ZnSO4 group showed obvious inflammatory cell infiltration, alveolar wall fracture, and lung structure destruction. Compared with the control group(14.78±2.82)×104mL-1, the total number of cells in BALF increased significantly in the PM2.5 group(24.11±5.30)×104 mL-1 and two ZnSO4 groupsboth (24.00±4.61)×104 mL-1 (P < 0.05), but there was no difference among the exposure groups. Compared with the control group(1.40±0.14) g·L-1, the total protein levels of BALF in the PM2.5 group, low ZnSO4 group, and high ZnSO4 group were significantly increased(2.58±0.50), (2.69±0.41), (3.62±0.98)g·L-1 (P < 0.05), and the increase in the high ZnSO4 group was more significant than that in the PM2.5 group. Compared with the control group(44.18±11.54)U·L-1, the PM2.5 group, low ZnSO4 group, and high ZnSO4 group(443.02±123.33), (185.16±64.00), (428.37±70.71)U·L-1 showed increased LDH levels in BALF (P < 0.05), and the PM2.5 group and high ZnSO4 group were obvious. Compared with the control group(9.54±2.38)×103ng·L-1, the PM2.5 group, low ZnSO4 group, and high ZnSO4 group(20.51±3.04)×103, (15.98±0.53)×103, (26.36±4.87)×103 ng·L-1 were significantly increased in IL-1β levels (P < 0.05), and the increase was significant in the high ZnSO4 group compared with the other two groups (P < 0.05).
    Conclusion Zinc ions in PM2.5 could induce lung inflammation in mice.

     

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