[Regulative effect of STAT1 on inflammation of lung tissue in bleomycin-induced rat interstitial pulmonary fibrosis].

OBJECTIVE: To investigate the role of signal transducer and activator of transcription 1 (STAT1) in alveolar macrophage (AM) in bleomycin-induced rat pulmonary fibrosis.

METHODS: Fifty adult female Wistar rats were randomly divided into two groups. The rats of BLM group were intratracheally instilled with bleomycin (BLM), and those of the control group with normal saline(NS). The kinetic change of STAT1 activation and the intercellular adhesion molecule-1 (ICAM-1) expression in AM were examined.

RESULTS: STAT1 was slightly activated in AM of NS group. After bleomycin treatment, the STAT1 activation of AM significantly increased on day 1, reached the peak value on day 7, and then gradually decreased, yet it remained significantly above the value of the NS group on day 28 (P < 0.05). There were a few positive staining cells for ICAM-1 expression in AM of NS group. After intratracheal instillation of bleomycin, the number of positive staining cells for ICAM-1 expression significantly increased on day 1, reached the peak value on day 7, gradually decreased from then on, but still it was higher than that of the NS group on day 28 (P < 0.05). There was a significant correlation between STAT1 activation and ICAM-1 expression in AM (r = 0.913, P < 0.01); moreover, ICAM-1 expression in AM was significantly correlated with the degree of inflammation in lung tissue (r = 0.947, P < 0.01).

CONCLUSION: STAT1 was found abnormally activated in AM in bleomycin-induced rat interstitial pulmonary fibrosis (IPF). The abnormal STAT1 activation may play a role in the pathogenesis of acute alveolitis and pulmonary fibrosis.