Abstract
Abstract: :
Purpose:It was shown previously (Spee CK, et al. IOVS 2004; ARVO E–Abstract 5094) using a lens extraction proliferative vitreoretinopathy (PVR) model that C57Bl/6 mice develop a higher amount of retinal fibrosis than 129S3/SvImJ mice. Real–time PCR was used to study the gene expression of factors involved in fibrosis to determine which genes played the most significant roles in the overall fibrotic response. Methods: Adult C57Bl/6 and 129S3/SvImJ mice were anesthetized and an incision was made in the cornea with a razor blade and extended using iridectomy scissors. The crystalline lens was extracted out by gently applying pressure around the limbus. The vitreous cavity was filled with 1% hyaluronate, and Iso–Dent, an adhesive, was used to close the corneal incision. Eyes were removed from mice at 12 hours, 24 hours, 4 days, 7 days, and 24 days after lens extraction (n=8 for each group). The lens was removed after enucleation for control C57Bl/6 (n=8) and 129S3/SvImJ (n=8) groups. Real–time PCR was used to determine the gene expression of collagen I, transforming growth factors beta–1 and beta–2 (TGF–ß1 and TGF–ß2), connective tissue growth factor (CTGF), matrix metalloproteinase 2 (MMP2), tissue inhibitor of metalloproteinase 1 (TIMP–1), bone morphogenic proteins 4 and 7 (BMP–4 and BMP–7), and tumor necrosis factor–alpha (TNF–α) for each sample. Results:Collagen I gene expression was over 3 times greater in C57Bl/6 mice, the more fibrotic strain, than in 129S3/SvImJ mice at 24 hours and at 7 days reached a peak expression level for both strains. There was no significant difference between strains for TGF–ß2 expression, but TGF–ß1 expression was over 3 times greater in C57Bl/6 than in 129S3/SvImJ mice at 24 hours. CTGF expression at 24 hours was also significantly higher in C57Bl/6 than in 129S3/SvImJ mice. MMP2 expression was significantly higher in 129S3/SvImJ mice than in C57Bl/6 mice at 12 hours and 7 days. TIMP–1 expression was higher in C57Bl/6 mice at 24 hours but higher in129S3/SvImJ mice at 4 days. There were not any significant differences between the two strains in BMP–4 expression, but BMP–7 expression was higher in C57Bl/6 mice at 24 hours, 4 days, and 7 days. TNF–α expression was higher in C57Bl/6 than in 129S3/SvImJ mice at 24 hours. Conclusions: The difference in response to the lens extraction model by the more fibrotic C57Bl/6 mouse strain and the less fibrotic 129S3/SvImJ may be related to differences in expression of TGF–ß1 and MMP2 genes.
Keywords: proliferative vitreoretinopathy • gene/expression • wound healing