Wistar大鼠肺孢子虫肺炎的实验研究

Experimental study of Wistar rats with pneumocystis pneumonia

目的建立肺孢子虫感染大鼠动物模型,并研究肺孢子虫感染引起的大鼠肺脏、肝脏及脾脏组织病理变化,为肺孢子虫致病机制研究提供依据。方法雌性Wistar大鼠54只,分成实验组和正常对照组。实验组大鼠37只,给予腹股沟皮下地塞米松注射,1 mg/次,2次/周;对照组大鼠17只,给予腹股沟皮下生理盐水注射,0.2 ml/次,2次/周。两组均给予含1 mg/ml盐酸四环素水溶液喂养。第8周对所有大鼠进行解剖,取肺、肝及脾组织观察组织大体改变,制作肺、肝、脾印片及病理组织切片,观察模型建立效果及肺肝脾组织病理变化。结果经瑞士-姬姆萨染色证实,实验组37例肺组织印片中35例发现肺孢子虫包囊,占94.6%,肝脏及脾脏印片均未查见肺孢子虫包囊。病理检查发现肺泡上皮不同程度增生、肺泡腔内有多少不等的泡沫样渗出物、肺泡间质增宽、炎细胞浸润等病理变化,部分小血管周围多量浆细胞、淋巴细胞浸润,呈袖套样外观,少量肺泡腔扩张及肺组织实变;六亚甲基四胺银染色可见肺泡壁及肺泡腔渗出物中呈中心点状深染黑色包囊。肝小叶基本正常,肝细胞水肿变性占56.8%,汇管区及中央静脉旁炎细胞浸润达97.3%;脾脏红髓白髓清晰可见,红髓髓窦内可见红细胞,白髓内可见多核巨细胞。对照组中,肺脏、肝脏无明显病理变化,脾脏组织红髓髓窦内也可见红细胞,与实验组无明显差异。结论连续8周糖皮质激素注射可成功诱导肺孢子虫肺炎大鼠模型,检出率高达94.6%;糖皮质激素相关免疫低下与肺孢子虫感染发生密切相关;肺孢子虫感染大鼠肺脏及肝脏发生不同程度的病理变化,该模型可作为肺孢子虫致病机制及其他研究的平台。

Objective To establish an experimental model ofpneumocystis pneumonia in Wistar rats and study the pathological changes of their lung, liver and spleen tissue for the study of PC pathogenesis. Methods Fifty-four female Wistar rats of clean grade were allowed to drink-tetracycline solution with the concentration of 1 rag/m1 and divided into two groups, the experimental group （n=37） with a subcutaneous injection of dexamethasone by a dose of 1 rag/time per rat twice a week and the control group （n=17） with the same way of injection by physiological saline simultaneously 0.2 ml per time The pathological and etiological examinations were undertaken after 8 weeks. Results Wright-Giemsa Stain confirmed that PC cyst was found in the lung tissue printing of 35 cases （94.6%） in the experimental group, while no PC cyst was found in liver and spleen printing. The pathological examination showed that there were different degrees of alveolar epithelial hyperplasia, varying amounts of foamed exudates in alveolar cavity, alveolar mesenchyme broadening, inflammatory cells infiltration and other pathological changes; numerous plasma cells and sleeved lymphocytes infiltration could be observed around some small blood vessels, while a small amount of alveolar cavity was expanded and consolidation of the lung tissue could be found; GMS staining showed alveolar walls and exudates of alveolar cavity with deep-dyed black cyst in the center points. The hepatic lobule was basically normal and 56.8% of the liver cells were with edema and degeneration, while 97.3% of the inflammation cells were infiltrated in the portal area and near the central vein; red pulp and white pulp were clearly visible in spleen. 51.3% of the medullary sinus was full of red blood ceils while multinuclear giant cells could be seen in white pulp. In the control group, no obvious pathological changes could be found in lung and liver, and red cells were visible in red pulp of spleen, which were not different with the experimental group. Conclusions Corticosteroid injections for 8 weeks could successfully induce the model of pneumocystis pneumonia in rats with the detection rate up to 94.6%. There was a strong link between PC infection and immunosuppression with glucocorticoid. Various degree of changes in the lung and the liver could be found by histulogic examination. This animal model could be used as a platform of investigating the pathogenic mechanism and other study of PC infection.