Activation of latent transforming growth factor beta during chlamydia trachomatis -induced murine pneumonia

Transforming growth factor beta (TGFβ) is a multifunctional cytokine with potentially important roles in both host defence and immunopathogenesis. Latent, but more importantly, active TGFβ was significantly elevated in bronchiolar lavage fluid from lungs of mice infected with murine Chlamydia trachomatis. Induction of both latent and active TGFβ in these infected animals was highest at day two after infection (2 to 4-fold) compared with day 15 (1 to 2-fold). Both active and latent TGFβ1 and TGFβ2 isoforms were detected. Quantitative reverse transcription polymerase chain reaction (RT-PCR) assay showed a slight but significant increase in PCR product for TGFβ1, but Northern analysis for TGFβ1 in lung tissue was not significantly different between treatment groups. No significant change was observed for TGFβ2 mRNA by RT-PCR. The increase in active and latent TGFβ in these lung lavages from mice infected with C. trachomatis appears to be primarily post-transcriptionally regulated.