Therapeutic Effects Of Aerosolized Signal Transducer And Activator Of Transcription 1 Antisense Oligonucleotide Administered At Different Time Points On Bleomycin-induced Pulmonary Fibrosis Rat

Objective: To investigate the effects of inhaling signal transducer and activator of transcription 1 (STAT1) antisense oligonucleotide (ASON) on alveolitis and fibrosis, the concentrations of platelet-derived growth factor (PDGF),transforming growth factor-β1 (TGF-β1) and tumor necrosis factor-α(TNF-α) in the bronchoalveolar lavage fluid (BALF), the mRNA levels of typeⅠandⅢcollagen in lung tissue in bleomucin (BLM)-induced rat pulmonary fibrosis at different time point, and to search for the optimal time of administration. Methods: Twenty-five adult female Wistar rats were randomly divided into 5 groups: BLM group, provided intratracheal perfusion of BLM so as to establish animal models of alveolitis and pulmonary fibrosis and then aerosolized with normal saline (NS); NS group, offerred intratracheal perfusion of NS and then aerosolized with NS; ASON 0 d group, provided intratracheal perfusion of BLM and then aerosolized with STAT1 ASON immediately; ASON 7 d group, provided intratracheal perfusion of BLM and then aerosolized with STAT1 ASON 7 days later; and ASON 14 d group, offerred intratracheal perfusion of BLM and then aerosolized with STAT1 ASON 14 days later. Aerosolizition was repeated once every other day for 4 times. Twenty-eight days after intra-tracheal perfusion the rats were sacrificed. Their part lungs were taken out to undergo pathological examination. NS was infused into the right lungs to get bronchoalveolar lavage fluid (BALF). Enzyme linked immunosorbent assay (ELISA) was used to examine the concentrations of PDGF,TGF-β1 and TNF-αin the BALF. The mRNA levels of typeⅠandⅢcollagen in the lung tissue were measured by reverse transcription-polymerase chain reaction (RT-PCR). Results: (1) The pathology result of the lung tissue: In NS group, alveolar structure showed no signs of septal oedema, inflammation or fibrosis. In BLM group, alveolar structure was destroied, interstitial substance proliferated, the wide fibrosis was formed. At the same time, the alveolitis existed. In ASON 0 d group, alveolar structure was almost integrated, accompanied by infiltration of inflammatory cells and proliferation of collagen fibers. Compared with the BLM and ASON 14 d groups, the alveolitis and pulmonary fibrosis of the ASON 0 d group were obviously milder. The scores of alveolitis and pulmonary fibrosis of the ASON 0 d group were (1.80±0.84) and (2.60±0.55) respectively, both significantly lower than those of the BLM group [(2.40±0.55) and (4.40±0.55) respectively] and those of the ASON 7 d group [(2.20±0.45) and (3.00±0.71) respectively] (all P<0.05). In ASON 7 d group, alveolar structure was partly complete, associated with infiltration of inflammatory cells and proliferation of collagen fibers. Compared with BLM group, the extent of alveolitis was similar with ASON 7 d group. However, the degree of fibrosis was significantly lower than the extent in BLM and ASON 14 d group. The scores of pulmonary fibrosis of the ASON 7 d group was significantly lower than those of the BLM and ASON 14 d groups (both P<0.05). (2) The concentrations of PDGF,TGF-β1 and TNF-αin BALF of the ASON 0 d group were (42.52±4.37) pg/ml,(48.11±3.46) pg/ml and (1.93±0.14) ng/ml respectively, significantly lower than those of the BLM group [(56.26±6.85) pg/ml,(57.67±2.46) pg/ml and (2.45±0.25) ng/ml respectively, P<0.05]. The concentration of TGF-β1 in BALF of the ASON 0 d group was evidently less than one of the ASON 7 and14 d group [(51.42±3.57) pg/ml,(55.83±1.79) pg/ml, both P<0.05]. The concentration of TGF-β1 in BALF of the ASON 7 d group was [(51.42±3.57) pg/ml] evidently less than one of the BLM and ASON 14 d group(P<0.05). The concentration of PDGF in BALF of the ASON 14 d group was [(45.85±2.08) pg/ml] evidently less than one of the BLM group (P<0.05). Conclusion: STAT1 ASON administered in the early stage helps inhibit the pulmonary fibrosis procedure, and the earlier the drug is administrated the better effect would be obtained. Aerosolized STAT1 ASON can be used as a therapeutic method for pulmonary fibrosis.