肺炎衣原体在血管平滑肌细胞中的生长状态及细胞超微结构的观察

The proliferative characteristics of Chlamydia pneumoniae in vascular smooth muscle cells and ultrastructural changes in infected cells

目的观察肺炎衣原体(Chlamydia pneumoniae,Cpn)在血管平滑肌细胞(VSMC)中的生长发育情况和细胞超微结构的改变,了解青霉素对Cpn感染状态的影响。方法利用免疫荧光染色鉴定Cpn感染VSMC情况;用透射电镜观察感染24h、48h和72h后Cpn在VSMC中的形态和细胞超微结构的变化,及经青霉素处理后Cpn生长状态的改变。结果免疫荧光染色观察到Cpn在VSMC内形成包涵体和点状感染灶。透射电镜观察到细胞内Cpn包涵体逐渐成熟的过程及典型的原体(EB)和网状体(RB)结构,其中在感染48h时部分包涵体或单个RB发育受限,72h时包涵体膜消失;细胞内线粒体和粗面内质网初期增多,后期扩张变形。此外,青霉素处理后Cpn不形成典型包涵体且RB结构异常。结论 Cpn感染VSMC的能力与易感细胞相比较弱,虽包涵体及其EB和RB形态结构与在易感细胞相似,但部分发育停滞;Cpn在VSMC的发育周期不足72h。青霉素干预能抑制Cpn在VSMC中的生长发育。感染后VSMC超微结构的变化为进一步研究细胞功能的改变提供了依据。

Objective To observe the proliferative characteristics of Chlamydia pneumoniae （Cpn） in vascular smooth muscle cells （VSMCs） and the ultrastructural changes in infected VSMC in order to investigate the effect of penicillin on Cpn proliferation in VSMCs. Methods Cpn infection of VSMCs was identified by immunofluorescence staining. At 24 h, 48 h, and 72 h post-infection, the proliferative characteristics of Cpn in VSMCs, uhrastructural changes in infected VSMCs, and morphological changes in Cpn inclusion after penicillin treatment were observed with transmission electron microscopy （TEM）. Results Sites of Cpn inclusion and infection were observed in VSMCs using immunofluorescence staining. TEM results revealed that Cpn inclusions gradually matured in VSMCs and took the typical forms of elementary bodies （EB） and reticulate bodies （RB）. Forty-eight h post infection, the proliferation of some inclusions or single RB was inhibited, and the inclusion body membrane disappeared 72 h post-infection. UltrastructuraI changes in infected VSMCs were observed： in the early stage, cell organelles of VSMCs, including mitochondria and rough endoplasmic retic- ulum, increased and later became distended and deformed. In addition, only aberrant RBs were observed, and no typical Cpn inclusions were seen in the cytoplasm after penicillin treatment. Conclusion Cpn has diminished ability to infect VSMCs compared to susceptible cells; although the ultrastructure of its inclusions, EBs, and RBs is similar to that in susceptible cells. The development of some inclusions, EBs, and RBs was halted. Moreover, the developmental cycle of Cpn in VSMCs takes less than 72 h. Penicillin can inhibit the growth and development of Cpn in VSMC. The ultrastruc tural changes in infected VSMCs provide a basis to further investigate the alteration of cell function.