Chlamydia pneumoniae dissemination and atherosclerosis

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Current studies have revealed that the obligate intracellular bacterium Chlamydia (Chlamydophila) pneumoniae is associated not only with respiratory diseases but also with atherosclerosis. In the present study, to understand the viability and growth potential of C.pneumoniae detected in blood of healthy persons, we first attempted to detect C.pneumoniae transcript in peripheral blood mononuclear cells (PBMCs) obtained from 70 healthy donors by real-time RT-PCR method. The presence of C.pneumoniae transcript in PBMCs from blood of healthy human donors was assessed by real-time RT-PCR-using primers for C.pneumoniae 16S rRNA. Out of 70 donors (18.5 %) showed the presence of bacterial transcript in cultured PBMCs. Prevalence of bacterial detection and bacterial numbers were significantly increased in PBMNC cultures incubated with cycloheximide. These results showed that viable C.pneumoniae might be present in healthy human PBMCs. Although several studies reported C.pneumoniae systemic diss … More emination from lung in animal model by DNA-based qualitative methods, the lack of a suitable animal model for permitting viable C.pneumonia dissemination from lung to blood has impeded the understanding of how viable C.pneumoniae can reach blood vessels and trigger the development of atherosclerosis. Therefore, we next studied the susceptibility of non-obese diabetic (NOD) mice to dissemination of viable C.pneumoniae from lung to blood, as detected by real-time RT-PCR. Following multiple intranasal inoculations, bacteria in lung were detected in NOD mice with diabetes (38.5%, n=13) as well as ICR mice (40%, n=10), but prevalence of bacteria in NOD mice without diabetes [Pre-diabetic NOD mice (n=8) and non-diabetic retired NOD mice (n=13)] was very low (5.2%, n=21). The bacteria were only detected in cultured PBMCs (53.8 %) of the NOD mice with diabetes. The prevalence of bacterial detection appeared to be increased in PBMC cultures incubated with hydrocortisone. Cultivation of C.pneumoniae from cultured PBMCs from all NOD mice was unsuccessful. Results of immunostaining with fluorescein isothiocyanate-conjugated anti-Chlamydia monoclonal antibody also showed the presence of bacterial antigens in the lungs and the PBMCs judged as positive by the RT-PCR. Thus, diabetic NOD mouse is sensitive to C.pneumoniae infection in which a possible dissemination of viable bacteria from lung to blood, and the animal model established in this study may be useful for understanding dissemination of C.pneumoniae infection. Less