Induction of matrix metalloproteinases 2 and 9 following stress to the lens

Matrix metalloproteinase 2 and 9 (MMP-2 and 9, also known as gelatinase A a nd B) have been implicated in a number of eye diseases, bur their possible involvement in lens pathology is yet to be determined. In the present study , we therefore investigated a possible role of matrix metalloproteinases in cataract and posterior capsule opacification, Whole porcine lenses were re moved from the eye and cultured in either Eagles Minimum Essential Medium ( EMEM) or EMEM supplemented with 1 mM hydrogen peroxide, The medium was samp led and changed every 2 days. On some occasions a sham cataract operation w as performed on cultured lenses. The resulting capsular bag was secured to a Petri dish and cultured in EMEM. Culture media from all preparations were analysed for MMP-2 and 9 activity by gelatin zymography Media samples from lenses which maintained clarity over the 6 day culture period did not disp lay any detectable gelatinolytic activity. However, media from cataractous lenses demonstrated a gelatinolytic band, which had similar molecular weigh ts to the pro-form of MMP-2. In addition to this band, bands with a similar molecular weight to pro-MMP-9 and its dimeric form were also detected in s amples obtained from capsular bag preparations within 24 hr. The data prese nted indicate that normal lenses have undetectable gelatinase activity. How ever, there is an associated expression of gelatinases with pathological st ates of the lens, and therefore gelatinase expression could play an importa nt role in cataractogenesis and posterior capsule opacification. (C) 2000 A cademic Press.