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

1.单次感染试验：采用（NZWxBXSB）F1。雌性小鼠，其中50%在24周龄时发生自发性心肌梗塞。小鼠在16周龄时鼻内接种肺炎衣原体KKpn-15菌株（10^5 FU/小鼠）。接种后3d死亡率为56%，7 d死亡率为100%。从所有受试肺中分离出肺炎衣原体，肺标本的组织学结果与肺炎一致。因此，提示肺炎衣原体具有依赖于宿主条件而诱发致死性肺炎的潜力。2.多重感染实验在确认在小于10^4FU/小鼠的剂量下不发生致死性肺炎后，在16周龄时鼻内接种肺炎衣原体KKpn-15菌株（10^4LFU/小鼠）。随后，在初始接种后35、42、49天重复接种3次。在每个指定时间点处死三只小鼠，直至开始后63天， ...更多信息 分别于接种后第3、7、14天在肺组织中分离出肺炎衣原体，PCR检测肺炎衣原体阳性。然而，即使多次接种，在此后的肺和心脏中也未检测到它。B）病理学发现：观察到初次接种后从急性肺部感染向慢性感染的转变。在心脏中，没有心肌梗死和动脉硬化改变。c）通过直接免疫荧光抗体（DFA）试验检测：在感染的早期阶段在肺中检测到肺炎衣原体阳性。d）免疫组化染色（ABC法）检测：多次接种后的心肌中未见阳性染色。e）冠状动脉形态定量分析：为了定量分析冠状动脉内膜厚度，我们使用IBAS系统应用计算机辅助图像分析。测量内径大于200 μ m的冠状动脉的周长、截面面积及其比值（截面面积/周长; S：G比值）。接种组和对照组的S：G比值分别为16.09和16.52，差异不显著。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