Effects of interleukin-1α on the expression of matrix metalloproteinases and tissue matrix metalloproteinase inhibitors in swine trabecular meshwork cells

Abstract

Background Obstruction of aqueous humor out flow pathway or abnormality of the extracellular matrix( ECM ) of trabecular meshwork cells causes high intraocular pressure. The balance of matrix metalloproteinases (MMPs) and tissue inhibitors of matrix metalloproteinases(TIMPs) is critical for the metabolism of ECM. Interleukin1α(IL-1α) can influence outflow of aqueous humor by regulating MMPs level. Objective This study was to investigate the effect of interleukin-1α on the expression of MMP-2,MMP-3 and TIMP-I in cultured swine trabecular meshwork cells.Methods Swine sclera with trabecular meshwork tissue was isolated from 20 swine eyes and cultured with explant cultured method. Cultured cells were passaged and third generation cells were identified by fibronectin ( FN ) and laminin ( LN ) staining. After 24 hours of serum starvation, trabecular meshwork cells treated with IL-1α at the concentration of 10 mg/L were regarded as the IL group,and serum-free culture medium used to treat trabecular meshwork cells was regarded as the control group. The expression of MMP-2, MMP-3 and TIMP-1 proteins in trabecular meshwork cells were detected by immunohistochemistry,and the expression of MMP-2 mRNA, MMP-3 mRNA and TIMP-1 mRNA were detected by RT-PCR. The examination results were compared between the two groups. Results The third generation of cells were positive for FN and LM. Compared with the control group, the expression levels of MMP-3 and TIMP-1 proteins(A value) in trabecular meshwork cells were significantly higher in the IL group than the control group(t=-7. 694,t =-5. 199,P＜0. 05) ,but no obvious difference was found in the expression of MMP-2 between the two groups( t=-2. 365, P＞0.05 ). The higher expression levels in MMP-3 mRNA and TIMP-1 mRNA (A value) in trabecular meshwork cells were seen in comparison with the control group (t =-3. 025,t=-1. 921 ,P＜0. 05). However,similar results were found in the expression of MMP-2 mRNA between the two groups(t =- 1. 173, P＞0.05 ). Conclusions The overexpression of MMP-3 and TIMP-1 proteins and their mRNA leads to the imbalance of MMP-3/TIMP-1 and promotes the decomposition of ECM in the trabecular meshwork, and therefore increases aqueous outflow. Key words: Interleukin-1 α; Trabecular meshwork cell; Matrix metalloproteinases ; Tissue inhibitors of matrix metalloproteinases; Extracellular matrix