大鼠肺孢子虫肺炎肺脏病理学变化的动态研究

Study on the experimental pathological changes on the rat of pneumocystis carinii pneumonia

目的研究大鼠肺孢子虫肺炎(PCP)不同病程的动态病理学变化。方法将雌性清洁级SD大鼠50只随机分成实验组和对照组,每组25只。实验组采用皮下注射地塞米松1mg/只/次、每周2次免疫抑制的方法诱导建立PCP的动物模型,对照组则注射相同剂量的灭菌生理盐水。在所有大鼠的饮水中加入1g/L盐酸四环素预防继发性细菌感染。免疫抑制3、5、7、9、11周后,每组各取5只大鼠进行解剖,分别制作肺组织印片,姬氏染色,检查肺孢子虫包囊,同时制作肺组织病理切片,HE染色,观察肺组织的病理学变化。结果用地塞米松诱导大鼠3周,其肺组织印片未查见肺孢子虫包囊,肺组织也未见明显的病理学改变;第5周,肺组织印片则均查见肺孢子虫包囊,肺组织出现病理学改变,并且病理学孜变随诱导时间的增加而加重;第7周主要表现为肺泡壁毛细血管轻度充血,间质内慢性炎性细胞浸润;至第9周至11周,则可见间质细胞增生、间质水肿、肺泡内出现粉红色泡沫样渗出物,部分肺组织呈现大片状实变区。对照组大鼠无异常表现,病原学检查阴性,肺脏组织无明显的病理学改变。结论应用皮下注射地塞米松免疫抑制诱导方法可成功建立肺孢子虫肺炎的大鼠实验模型,大鼠肺孢子虫肺炎的病理学改变以炎症、渗出、细胞浸润、间质细胞增生等为主,同时病理学改变随病程进展而加重。

Objective To study the pathological changes in the rat pneumonia by Pneumocystis carinii （PCP）. Methods Fifty female SD rats of clean grade were randomly divided into experimental and control groups. Animals in the experimental group were irnmunosuppressed by a quantitative subcutaneous injection of dexamethasone with a dose of 1 mg/time per rat twice a week. Those in the control group were undergone the same way of injection with physiological saline simultaneously. Meanwhile,for preventing from the potential infections caused by the other microbiological pathogens,all animals in both groups were allowed to drink tap water freely,which was dissolved with tetracycline with the concentration of 1 mg/ml. The pathological changes in both groups were observed. The pathological and etiological examinations were then undertake at 3,5,7,9,11 weks intervals. Lung smear made from the lung tissue of each rat was stained by Giemsa＇s stain,and were examined microscopically for identiflying the cysts of pneumocystis carinii （PC）. Histopathological sections of the lung tissues of the infected animals were stained by HE stain for the observation of histopathologieal changes. Results It was found that from the 5th week on,rats in the experimental group developed disease,and the cysts and trophozoites of P. Carinii were found in the lung smears of rats. Histopathologieally,there were significant changes with time in the experimental group,including interstitial pneumonia with hyperemia in the capillaries of alveolar wall and moderate infiltration with lymphocytes at 7th week. In 9th to 11 th week, proliferation of interstitial cells ,interstitial edema, red foamy alveolar exudates were observed. Neither etiologic nor histologic examination were negative in the normal control group. Conclusion There suits showed that the method with which quantitative doses of dexamethasone were subcutaneously injected with a dose of 1 mg/time per rat twice a week was suitable for establishing an animal model of PCP. It is concluded that the primafy histopathological of Pneumocystis carinii pneumonia in rats are exudation,infiltration with lymphocytes and proliferation of interstitial cells.