稀土氧化钕粉尘染毒大鼠不同时间点Ⅰ型和Ⅲ型胶原纤维含量及IL-12表达的研究

TypeⅠand Type Ⅲ Collagen and IL-12 in Rats Lung after Exposure to Neodymium Oxide Dust

目的探讨稀土氧化钕粉尘暴露对大鼠不同时间点肺组织中Ⅰ型和Ⅲ型胶原纤维含量和支气管肺泡灌洗液(BALF)中白介素-12(IL-12)表达的变化。方法选用125只SPF级成年SD雄性大鼠,体重(200±16)g,随机分为染尘组和对照组,采用气管非暴露插管灌注法建立模型,分别用稀土氧化钕粉尘悬液0.8 m L(50 mg/m L)和0.9%生理盐水0.8 m L进行一次性染尘。分别于染尘后第3、7、14、21和28 d各处死15只染尘组和10只对照组大鼠,收集BALF;采用酶联免疫吸附试验(ELISA)法分别测定染尘组和对照组大鼠BALF上清液中IL-12含量,肺组织分别进行HE染色、天狼猩红染色,运用Image-Pro Plus Version 4.5for Windows TM图象分析系统对肺组织中Ⅰ、Ⅲ型胶原纤维含量进行定量分析。结果稀土氧化钕粉尘致实验大鼠肺组织纤维化过程中可见Ⅰ、Ⅲ型胶原纤维的大量增生,染尘后早期主要以Ⅰ型胶原纤维增生为主。其中Ⅰ、Ⅲ型胶原纤维的表达量明显增加,与对照组相比,差异均有统计学意义(P<0.05)。肺组织病理学观察证实,染尘大鼠早期肺组织以炎症反应为主,且随染尘时间的延长炎症反应程度呈现加重的趋势。染尘后不同时间点大鼠BALF上清液中IL-12出现先减少后增加,在第7 d达到最低值后又呈现增加趋势,但均高于对照组(P<0.05)。结论稀土氧化钕粉尘诱导大鼠肺纤维化过程中Ⅰ型和Ⅲ型胶原纤维含量增多,且分布范围扩大。同时BALF上清液中IL-12出现高表达,表明IL-12的含量变化与稀土氧化钕粉尘致大鼠肺纤维化发生发展密切相关。

Objective To explore the change of typeⅠ and type Ⅲ collagen and IL-12 in the lung of rats after exposure to rare earth neodymium oxide dust at different time points. Methods One hundred and twenty five healthy adult male SD rats（ SPF grade）,weighted（ 200 ± 16） g,were randomly divided into a dust exposure group and a control group. The dust-exposure model was established by tracheal non-exposure intubation perfusion. The dust exposure group was treated once with a dust suspension containing 0. 8 m L（ 50 mg / m L） of rare earth neodymium oxide; and the control group was treated with 0. 8 m L of normal saline solution. Fifteen rats in the dust exposure group and 10 rats in the control group were killed at 3,7,14,21 and 28 days after exposure. The content of IL-12 in the supernatant of bronchoalveolar lavage fluid（ BALF） was detected by ELISA. The lung tissue was dyed with Sirius red and HE; typeⅠ and type Ⅲ collagen fibers were quantified by using image-Pro Plus Version 4. 5 for Windows TM image analysis system. Results The levels of typeⅠ and type Ⅲ collagen were increased significantly during the process of pulmonary fibrosis induced by rare earth neodymium oxide dust; typeⅠ collagen hyperplasia was predominant in the early period of dust-exposure. The levels of type Ⅰ and type Ⅲ collagen in the exposure group were significantly higher than those in the control group（ P〈0. 05）. Inflammation was the early change in lung tissue confirmed by pathological observation after exposure to dust,and there was a trend of increasing inflammation with the extension of time after exposure. The content of IL-12 in the supernatant of BALF was declined first and then climbed up; the minimum value was at the seventh day after exposure and then was increased,but the content was higher than that in the control group（ P〈0. 05）. Conclusions The level of typeⅠ and type Ⅲ collagen was increased significantly in the process of pulmonary fibrosis induced by rare earth neodymium oxide dust,and the distribution was wide. Meanwhile,a high expression of IL-12 was observed in the supernatant of BALF,which indicated that the change of IL-12 was closely related to the occurrence and development of pulmonary fibrosis in rats induced by rare earth neodymium oxide dust.