title: Expression of MMP-2, MT1-MMP, and TIMP-2 by cultured rabbit corneal fibroblasts under mechanical stretch.
abstract: Refractive surgery not only leads to tissue injury but also evokes mechanical stress increase of the cornea. How the mechanical stress affects the corneal matrix remodeling, specifically, matrix metalloproteinases (MMPs) and their inhibitors (tissue inhibitors of metalloproteinases; TIMPs) is not well understood. In this study, cultured rabbit corneal fibroblasts in vitro were subjected to regimen of 5%, 10%, or 15% equibiaxial stretch at 0.1 Hz for 3 or 24 h. MMP-2 protein level was measured by gelatin zymography and Western blotting. MMP-2, membrane type 1 MMP (MT1-MMP), and TIMP-2 mRNA levels were quantified by real-time quantitative PCR. Extracellular regulated protein kinase (ERK) phosphorylation protein levels were assessed by Western blotting. Our results showed that a 15% stretch resulted in increases in MMP-2 protein, MMP-2 mRNA, and MT1-MMP mRNA levels, but a decrease in TIMP-2 mRNA level. However, a 5% stretch caused decreases in MMP-2 protein and mRNA level, but an increase in TIMP-2 mRNA level, and no change in MT1-MMP mRNA level. A 15% stretch also caused a significant increase in ERK1/2 phosphorylation. Inhibition of the mitogenactivated protein kinase (MEK) pathway with PD98059 attenuated stretch-induced increase in MMP-2 production and ERK activity. These results suggest that small-magnitude stretching may promote corneal matrix synthetic events, whereas large-magnitude stretching promotes corneal matrix degradation by changing the balance between MMPs and TIMPs in corneal fibroblasts. Large-magnitude stretch-induced increase in pro-MMP-2 production was in an ERK-dependent manner.
authors.affiliation: Institute of Applied Mechanics and Biomedical Engineering, Taiyuan University of Technology, Taiyuan, Shanxi 030024, China Shanxi Key lab of Material Strength & Structural Impact, Taiyuan, Shanxi 030024, China School of Basic Medicine, Shanxi Medical University, Taiyuan, Shanxi 030001, China.
authors.forename: Chengxing
authors.initials: C
authors.lastname: Liu
authors.affiliation: Institute of Applied Mechanics and Biomedical Engineering, Taiyuan University of Technology, Taiyuan, Shanxi 030024, China Shanxi Key lab of Material Strength & Structural Impact, Taiyuan, Shanxi 030024, China.
authors.forename: Pengfei
authors.initials: P
authors.lastname: Feng
authors.affiliation: Institute of Applied Mechanics and Biomedical Engineering, Taiyuan University of Technology, Taiyuan, Shanxi 030024, China Shanxi Key lab of Material Strength & Structural Impact, Taiyuan, Shanxi 030024, China.
authors.forename: Xiaona
authors.initials: X
authors.lastname: Li
authors.affiliation: Institute of Applied Mechanics and Biomedical Engineering, Taiyuan University of Technology, Taiyuan, Shanxi 030024, China Shanxi Key lab of Material Strength & Structural Impact, Taiyuan, Shanxi 030024, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Song
authors.affiliation: Institute of Applied Mechanics and Biomedical Engineering, Taiyuan University of Technology, Taiyuan, Shanxi 030024, China Shanxi Key lab of Material Strength & Structural Impact, Taiyuan, Shanxi 030024, China chenweiyi@tyut.edu.cn.
authors.forename: Weiyi
authors.initials: W
authors.lastname: Chen
keywords: Cyclic stretch; ERK; TIMPs; corneal fibroblasts; matrix metalloproteinases