[mRNA expression of basic fibroblast growth factor in the pulmonary tissues from rats repeatedly infected with mycoplasma pneumoniae].
OBJECTIVE
To investigate changes in mRNA expression of basic fibroblast growth factor (bFGF) in pulmonary tissues from rats repeatedly infected with Mycoplasma pneumoniae (MP).


METHODS
Rats were infected with MP for 9 times during a period of 24 weeks by ultrasonic nebulizing inhalation to establish animal models of chronic pulmonary MP infection. In situ hybridization was performed with bFGF cDNA probe and results were quantitatively analysed to measure the changes of bFGF mRNA expression in lung tissues.


RESULTS
(1) MP polymerase chain reaction (PCR) tests showed positive results in the bronchoalveolar lavage fluid (BALF) from MP infected animals (n = 4) while results were negative for BALF from the control rats (n = 4) and rats infected with MP but treated with erythromycin (n = 4). Bacterial cultures of the bronchial and the lung tissues were negative in all three groups. Observation with transmission electron microscope showed that interalveolar septa were widened with increased amount of collagen in the MP infected rats while there were no obvious abnormalities in the other two groups. (2) Positive expression of bFGF mRNA were found in alveolar walls of MP infected rats. No expression of bFGF mRNA was found in control animals. In the rats infected with MP but treated with erythromycin positive expression of bFGF mRNA was found to be scarcely distributed in alveolar walls. Quantitative analysis showed that the optical densities of bFGF mRNA expression were 41.32 +/- 10.44 in the MP infected rats (n = 4), which were significantly higher than those in the control group (0.30 +/- 0.13, n = 4, P < 0.01) and those in the MP infected and erythromycin treated rats (6.03 +/- 2.41, n = 4, P < 0.01).


CONCLUSIONS
Repeated pulmonary infection with MP can lead to up-regulation of bFGF mRNA expression, which suggests that bFGF might play a role in the pathogenesis of pulmonary interstitial fibrosis after repeated MP infection.
Liu
J
J
Department of General Medicine, Tongji Hospital, Tongji Medical University, Wuhan 430030.
Peng
D
D
Zhu
Z
Z
D000818:Animals; D001992:Bronchoalveolar Lavage Fluid; D004195:Disease Models, Animal; D004917:Erythromycin / Q000627:therapeutic use; D016222:Fibroblast Growth Factor 2 / Q000235:genetics*; D015870:Gene Expression; D008168:Lung / Q000378:metabolism* / Q000473:pathology / Q000648:ultrastructure; D008297:Male; D009177:Mycoplasma pneumoniae; D011019:Pneumonia, Mycoplasma / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D012333:RNA, Messenger; D051381:Rats; D017208:Rats, Wistar; D012008:Recurrence
D012333:RNA, Messenger; D016222:Fibroblast Growth Factor 2; D004917:Erythromycin