Objective

To observe the expressions of matrix metalloproteinase-2 (MMP-2) and tissue inhibitor of metalloproteinase-1 (TIMP-1) in rats with pulmonary fibrosis (PF) induced by bleomycin, and to explore the mechanisms of Shenlong Decoction in preventing and treating PF.
Methods

A total of 230 Wistar rats were divided into normal control group, untreated group, prednisone group, and low-, medium- and high-dose Shenlong Decoction groups. Wistar rats were intratracheally injected with bleomycin to induce PF. From the 2nd day, rats in the normal control and untreated groups were lavaged with normal saline (NS), and rats in the other groups were lavaged with prepared Shenlong Decoction by the same amount. Hemotoxylin-eosin (HE) staining and Masson staining were used to observe pathological changes in lung tissue at different time points, and to evaluate whether the model was successfully induced. Expressions of MMP-2 and TIMP-1 mRNAs in rats’ lung tissue were measured by reverse transcription-polymerase chain reaction (RT-PCR).
Results

Expressions of MMP-2 and TIMP-1 mRNAs in lung tissue of rats were observed from all groups at each time point. In comparison with the normal control group, on the 7th day, the transcription levels of MMP-2 and TIMP-1 mRNAs, especially the former, of the untreated group increased significantly (P<0.05 or P<0.01). On the 14th day, the transcription levels of MMP-2 and TIMP-1 mRNAs kept rising, especially the latter (P<0.05 or P<0.01). On the 28th day, the transcription level of MMP-2 decreased a little, while the transcription level of TIMP-1 mRNA did not stop increasing (P<0.05 or P<0.01). Compared with the untreated group, decrease of the transcription levels of MMP-2 and TIMP-1 mRNAs were observed in the treatment groups, especially the former, and this effect continued to the 28th day with the medium-dose Shenlong Decoction group decreasing most obviously (P<0.05 or P<0.01).
Conclusion

Shenlong Decoction may inhibit the expression of MMP-2 mRNA by up-regulating the expression of TIMP-1 mRNA so as to slow the progression of PF.

Key words: Pulmonary fibrosis, Bleomycin, Matrix metalloproteinase-2, Tissue inhibitor of metalloproteinase-1, Rats