Development of diabetes in non-obese diabetic mice promotes Chlamydia pneumoniae dissemination from lung to peripheral blood.

We examined a possible association between development of diabetes in non-obese diabetic (NOD) mice and dissemination of Chlamydia (Chlamydophila) pneumoniae from lung to peripheral blood. By real-time reverse transcription-polymerase chain reaction (RT-PCR) with primers for C. pneumoniae 16S rRNA, following multiple intranasal inoculations, we detected bacteria in lung in NOD mice with diabetes (38.5%) as well as Institute of Cancer Research, USA (ICR) mice (40%), but prevalence of bacteria in NOD mice without diabetes (pre-diabetic NOD mice and non-diabetic retired NOD mice) was very low (4.8%). The bacteria were only detected in peripheral blood mononuclear cells (PBMCs) cultured with hydrocortisone of the NOD mice with diabetes (53.8%). Results of immunostaining with fluorescein isothiocyanate-conjugated antichlamydia monoclonal antibody also showed the presence of bacterial antigens in the lungs and the PBMCs judged as positive by the RT-PCR. However, C. pneumoniae from cultured PBMCs of all NOD mice was undetected by cultivation method with inclusion-forming units assay. In addition, no influence of C. pneumoniae intranasal inoculation on development of diabetes in NOD mice was confirmed. Thus, the development of diabetes in NOD mouse appears to be one of critical factors for promoting the dissemination of C. pneumoniae from lung to peripheral blood.