Analysis of the arteriosclerotic change caused by Chlamydia pneumoniae infection in a experimental mouse model (W/BF1)

1.单一感染实验：选用(NZWxBXSB)F1。其中50%的雌性小鼠在24周龄时发生自发性心肌梗死。16周龄小鼠鼻腔接种肺炎衣原体KKpn-15株(10~5FU/只)。接种后3天死亡率为56%，接种后7天死亡率为100%。所有受试者的肺组织均分离到肺炎衣原体，组织学检查结果与肺炎相符合。2.多重感染实验在确认致死性肺炎的剂量低于10^4IFU/只小鼠后，16周龄的小鼠鼻内接种肺炎衣原体KKpn-15株(10^4LFU/只)。随后，在初始接种后的第35、42、49天重复接种3次。在每个指定的时间点处死3只小鼠，直到开始和…后63天A)分别于接种后第3、7、14天分离肺炎衣原体，肺组织中肺炎衣原体聚合酶链式反应阳性。B)病理改变：初次接种后，急性肺部感染转变为慢性感染。C)直接免疫荧光抗体(DFA)检测：肺炎衣原体感染早期肺组织呈阳性。D)免疫组织化学染色(ABC法)检测：多次接种后的心肌未见阳性染色。e)冠状动脉形态计量学分析：应用IBAS计算机图像分析系统对冠状动脉内膜厚度进行定量分析。测量冠状动脉内周长大于2 0 0微米的冠状动脉的周长、截面积及其比值(截面积/周长；S：G比值)。接种组S：体重比为16.09，对照组为16.52，差异无统计学意义。较少

1.Experiment of single infection : We used (NZWxBXSB)F1. female mice fifty percent of which develop spontaneous myocardial infarction at the age of 24 weeks. Mice were inoculated with C.pneumoniae KKpn-15 strain (1O^5FU/mouse) intranasally at the age of 16 weeks. Mortality rate was 56% at 3days, 100% at 7 days after inoculation. C.pneumoniae was isolated from all the lung tested and histological findings of the lung specimens were compatible with pneumonia. Therefore, it is suggested that C.pneumoniae has a potential to induce lethal pneumonia depending of the host condition.2.Experiment of multiple infections After confirming that lethal pneumonia does not occur at the dose less than 10^4IFU/mouse, mice were inoculated with C.pneumoniae KKpn-15 strain (10^4LFU/mouse) intranasally at the age of 16 weeks. Subsequently, inoculation was repeated 3 times at 35, 42, 49 days after initial inoculation. Three mice were sacrificed at each designated time point till 63 days after initiation and … More we observed chronological change of C.pneumoniae isolation rate and histological change of lung and heart.a)Detection of C.pneumoniae C.pneumoniae was isolated and PCR for C.pneumoniae was positive in lung at 3, 7, 14 post inoculation day respectively. However, it was not detected both in lung and heart thereafter even with multiple inoculation.b)Pathological findings : Transition from acute pulmonary infection to chronic infection after initial inoculation was observed. In heart, no myocardial infarction and arterioscrelotic change was observed.c)Detection by direct immunofluoresent antibody (DFA) test : C.pneumoniae was positively detected in lung at the early phase of infection. But in myocardium and coronary artery, no positive signal was detected at any time point.d)Detection by immunohistochemical staining(ABC method) : No positive staining was observed in myocadrium obtained after multiple inoculation.e)Morphometrical analysis of coronary artery : For the quantitative analysis of intimal thickness of coronary artery, we applied computer-assisted image analysis using an IBAS system. The girth, area of section and ratio of them ( area of section/girth ; S : G ratio) in coronary artery with the inner girth more than 200 mu m were measured. S : G ratio was 16.09 in inoculation group and 16.52 in control group showing no significant difference. Less