The effect of mechanical strain on matrix metalloproteinase production by bovine trabecular meshwork cells

Purpose. To evaluate the effects of mechanical stretching of trabecular mes hwork cells on matrix metalloproteinase activity. Methods. Cultured bovine trabecular meshwork cells grown on collagen-coated elastomer were subjected to 10% biaxial mechanical stretching. After vario us time intervals, culture medium was collected from stretched and nonstret ched control cells. Matrix metalloproteinase activity was studied by zymogr aphy and levels of inhibitors were determined by immunoblotting or immunoas say of the collected medium. Results. Trabecular meshwork cells subjected to mechanical strain showed in creased stromelysin and gelatinase A activity at 24 to 72 hours after initi al stretching compared to control cells. By 72 hours of strain, stromelysin activity increased to up to 73% (p<0.01) whereas gelatinase A activity inc reased by 31% (p<0.05). The increased metalloproteinase activity was revers ible with relaxation of mechanical stretch. Levels of tissue inhibitor of m atrix metalloproteinase-1 and -2 remained unchanged during 72 hours of stre tch. Conclusions. Changes in mechanical strain on the trabecular meshwork, which may occur in vivo during changes in intraocular pressure, induce changes i n matrix metalloproteinase activity. The resultant alterations in the extra cellular matrix may affect outflow resistance through the trabecular meshwo rk in response to alterations in intraocular pressure.