Effects of type Ⅳ collagen,MMP-9 and TIMP-1 gene expression on the initiation of early phase radiation pulmonary fibrosis / 解放军医学杂志

ABSTRACT

Objective To investigate the gene expression profiles of type Ⅳ collagen, matrix metalloproteinase-9 (MMP-9) and tissue inhibitor of metalloproteinase-1 (TIMP-1) at the onset of radiation pulmonary fibrosis, so as to explore their possible roles in the pathogenesis of pulmonary radiation injury. Methods The whole lung was irradiated with 20Gy of 60Co ?-ray in C57 mice. At 1, 2 and 4 weeks after irradiation, both irradiated mice and corresponding number of normal control mice were sacrificed. Alterations in mRNA transcription of type Ⅳ collagen, MMP-9 and TIMP-1 were observed by RT-PCR at different time points post-irradiation. The mean optical density of electrophoretic bands was measured and analyzed by image analyzer. Result The mRNA expression of type Ⅳ collagen was up-regulated gradually after irradiation with the passage of time. The mean optical density of electrophoretic band was 0.202 at 1 week post irradiation and reached its peak value (0.340) at 4 weeks post irradiation; the mRNA expression of MMP-9 was up-regulated significantly and reached its peak value (0.730) at 1 week post irradiation. It began to lower at 2 weeks (0.592). The mRNA transcription of TIMP-1 began to increase slightly 1 and 2 weeks post irradiation (0.987) and reached its peak value (2.027) at 4 weeks post irradiation. Conclusion 60Co ?-ray can stimulate mRNA expression of type Ⅳ collagen, MMP-9 and TIMP-1 with different profiles at different time points. Complex interactions among them may result in early tissue remodeling after pulmonary radiation injury, and it bears close relation with subsequent pulmonary fibrosis.