Abstract
Purpose::
Matrixmetalloproteinases (MMP’s) have been associated with cortical cataract formation. The purpose of this study is to determine if prostaglandin analogue use increases the expression of certain MMP’s (MMP-1, MMP-2, and MMP-9) in human lens epithelial cells, thus providing a mechanism by which prostaglandin analogues could be cataractogenic.
Methods::
Observational Cohort Study. Capsulorhexis specimens were collected from patients undergoing cataract extraction from two groups; one group being patients treated with prostaglandin analogues to lower intra-ocular pressure and the second group being non-glaucomatous untreated patients. Immunohistochemistry was performed on the capsulorhexis specimens using antibodies against MMP-1, MMP-2, and MMP-9. Two observers masked to whether specimens were from the treated or untreated groups graded the degree of staining on a scale from 0 to 3. Also anterior capsule thickness was recorded as a measure of possible collagenase activity (MMP-2, MMP-9). Statistical analysis was performed using the Mann Whitney test.
Results::
Fourteen treated and 31 untreated specimens were collected. For each antibody, several specimens were lost during antigen unmasking accounting for the unequal numbers in the groups. Immunolabeling of variable intensity was observed with these three antibodies in the lens epithelial cells. The staining intensity for MMP-1 was 0.857 ± 0.748 for the treated group (n=7) and 1.156 ± 1.151 for the untreated group (n=16) (range: 0 - 3; p = 0.720). The MMP-2 staining intensity was 0.900 ± 0.615 for the treated group (n=10) and 0.760 ± 0.482 for the untreated group (n=26) (range: 0 - 1.5; p=0.614). MMP-9 staining intensity was 0.275 ± 0.786 for the treated group (n=10) and 0.260 ± 0.539 for the untreated group (n=24) (range: 0 - 2.5; p= 0.839). There was no significant difference in the anterior capsule thickness of the treated (0.207 ± 0.032, n=7) vs. untreated (0.180 ± 0.045, n=16) group (range: 0.118 - 0.268; p = 0.175).
Conclusions::
MMP-1, MMP-2, and MMP-9 are present in human lens epithelial cells attached to the central anterior capsule and their presence is variable between different patients. This study did not demonstrate a significant difference in the degree of immunostaining with these three MMP antibodies between patients on prostaglandin analogues versus those who were not. We also did not find any difference in anterior lens capsule thickness between the treated and untreated groups.
Keywords: cataract • drug toxicity/drug effects • microscopy: light/fluorescence/immunohistochemistry