Chronic and repeated Chlamydophila pneumoniae lung infection can result in increasing IL-4 gene expression and thickness of airway subepithelial basement membrane in mice.
OBJECTIVE
Chlamydophila pneumoniae infection has been associated with several pulmonary and cardiac diseases. However, it has not been explored for its ability to activate the same immunopathologic mechanisms of asthma, namely, a predominant Th2 immune response and structural changes that are termed airway remodeling. This study evaluated immune responses in the lung and airway pathology of BALB/c mice with chronic and repeated C. pneumoniae infections.


METHODS
Mice were inoculated intranasally with 5 x 10(6) inclusion-forming units of C. pneumoniae TWAR strain, and re-inoculated at 14 and 42 days after the primary inoculation. Cytokine gene expression in bronchoalveolar lavage (BAL) cells was analyzed by RT-PCR on day 70. Airway pathology was also evaluated by morphometric measurements.


RESULTS
A significant increase of interleukin (IL)-4 mRNA was detected in BAL cells in infected mice, and a significant increase in subepithelial basement membrane thickness of the airways was also noted in infected mice as compared with control mice (8.95 +/- 0.28 microm vs. 5.54 +/- 0.22 microm, p < 0.0001). We further analyzed the correlation between IL-4 cytokine expression and the increased subepithelial basement membrane thickness of airways in infected mice. We found that mice with increased IL-4 mRNA expression had significant increases in the thickness of subepithelial basement membrane as compared with mice without increased IL-4 mRNA expression (9.87 +/- 0.51 microm vs. 6.49 +/- 0.52 microm, p < 0.0001).


CONCLUSIONS
It is believed that our results demonstrated for the first time that chronic and repeated infections with C. pneumoniae increased IL-4 gene expression and thickness of airway subepithelial basement membrane in mice.
Chen
Chiung-Zuei
CZ
Department of Internal Medicine, National Cheng Kung University Hospital, Tainan, Taiwan.
Yang
Bei-Chang
BC
Lin
Tsun-Mei
TM
Lee
Cheng-Hung
CH
Hsiue
Tzuen-Ren
TR
D000276:Adjuvants, Immunologic / Q000235:genetics; D000704:Analysis of Variance; D000818:Animals; D001485:Basement Membrane / Q000276:immunology / Q000473:pathology*; D001992:Bronchoalveolar Lavage Fluid / Q000276:immunology / Q000382:microbiology; D023521:Chlamydophila Infections / Q000276:immunology*; D016993:Chlamydophila pneumoniae / Q000235:genetics / Q000276:immunology* / Q000302:isolation & purification; D015847:Interleukin-4 / Q000235:genetics / Q000276:immunology*; D008168:Lung / Q000276:immunology* / Q000473:pathology; D051379:Mice; D008807:Mice, Inbred BALB C; D012333:RNA, Messenger / Q000235:genetics / Q000276:immunology; D012137:Respiratory System / Q000276:immunology* / Q000473:pathology; D020133:Reverse Transcriptase Polymerase Chain Reaction
D000276:Adjuvants, Immunologic; D012333:RNA, Messenger; D015847:Interleukin-4