煤燃烧排放的细颗粒物对大鼠肺的免疫损伤

Immunologic injuries in lung of rats induced by particulate matter emitted by coal combustion

目的研究燃煤细颗粒物(PM2.5)对大鼠肺部的免疫损伤。方法采集空气动力学直径≤2.5μm的PM2.5并分析测试其化学成分,研究因燃煤而产生的PM2.5对大鼠肺部的免疫损伤。将40只雄性6周龄Wistar大鼠随机分为4组,分别对4组大鼠气管滴注生理盐水、低浓度(1.5 mg/kg·bw)、中浓度(7.5 mg/kg·bw)及高浓度(37.5 mg/kg·bw)PM2.5悬液,分别于24和48 h后处死动物,检测其血常规和肺泡灌洗液(BALF)中白介素-6(IL-6)、肿瘤坏死因子(TNF-α)及转化生长因子(TGF-β1)等氧化炎症因子,并制作肺组织病理切片。结果一定的染毒时间和染毒剂量可明显提高大鼠白细胞数(WBC)、明显降低红细胞数(RBC)。急性染毒48 h后,低浓度组和高浓度组染毒使大鼠肺组织中TNF-α升高(P<0.05)。对大鼠肺部病理观察显示,急性染毒导致大鼠肺部产生病理变化,特别是中浓度和高浓度染毒24和48 h后,大鼠肺泡严重压缩、溃不成形,血管和支气管内产生结晶,炎细胞浸润。结论燃煤PM2.5急性染毒24 h后,导致大鼠血液WBC升高、激发TNF-α的分泌,大鼠表现出积极的免疫应对;急性染毒48 h后,大鼠血液WBC和RBC数量降低,大鼠表现出免疫系统调节能力降低。随着染毒污染物浓度的升高,大鼠肺部组织的不利影响逐渐加重。

Objective To study the immunologic injury in respiratory system of rats induced by fine particulate matter(PM2.5)emitted by coal combustion.Methods Coal combustion emitting PM2.5 samples(the aerodynamic diameter≤2.5μm)were collected,their chemical composition measured and their immunologic injuries in lung of rats studied.Forty individuals of six-weeks-old male Wistar rats were randomly divided into four groups,each with 24 or 48 h treatments.Normal saline,PM2.5 suspensions with low concentration(1.5 mg/kg·bw),medium concentration(7.5 mg/kg·bw)and high concentration(37.5 mg/kg·bw)were induced by intracheal instillation in rats respectively.After 24 and 48 h exposure respectively,the rats were executed and the routine blood and inflammatory cytokines(IL-6,TNF-α,TGF-β1)of Broncho alveolar lavage fluid(BALF)were measured,and the pathological sections of lung tissues were observed.Results Certain exposure time and toxic dose have significantly increased the number of white blood cells(WBC),reduced the red blood cells(RBC)number in rats.In the case of 48 h acute exposure to PM2.5,TNF-αin rats’lung tissues was increased(P<0.05).Acute exposure caused pathological changes in rat lungs.In particular,after exposure to medium and high concentrations,the alveoli of rats were severely compressed and collapsed,resulting in crystallization and inflammatory cell infiltration in the blood vessels and bronchi.Conclusion Acute exposure to coal emitting PM2.5 for 24 hours,it was showed positive immune response by increasing blood leukocyte count and TNF-αsecretion;after 48 hours of acute exposure,rats reduced the immune system regulation ability by decreasing the number of WBC and RBC.With the increase of exposure PM2.5 concentration,the adverse effects on rat lung tissue have gradually been aggravated.