Downregulation of matrix metalloproteinase‑19 induced by respiratory syncytial viral infection affects the interaction between epithelial cells and fibroblasts.

The present study was designed to examine the expression and function of matrix metalloproteinase‑19 (MMP‑19)， which is downregulated following respiratory syncytial virus (RSV) infection. The diverse expression levels of MMP were examined using a designed cDNA expression array. The expression and secretion of MMP‑19 was examined using reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR) analysis and ELISA， respectively. The proliferation of epithelial cells and lung fibroblasts were examined using flow cytometry. The epithelial‑mesenchymal transition (EMT) was also examined by performing western blot and RT‑qPCR analyses. The results of the cDNA assay showed that infection with RSV resulted in the abnormal expression of certain metalloproteinases. Among these， the expression of MMP‑19 decreased 3 and 7 days following infection. By using flow cytometric， western blot and RT‑qPCR analyses， the present study demonstrated that the downregulation of MMP‑19 inhibited the proliferation of epithelial cells， promoted the EMT and induced the proliferation of lung fibroblasts. Taken together， the findings of the present study suggested that the downregulation of MMP‑19 following RSV infection may be associated with the development of airway hyper‑responsiveness.