Abstract
Purpose :
Glaucoma is a multifactorial disease where inflammatory pathways play a role in pathogenesis and maintenance of normal extracellular matrix (ECM) turnover. Human tears is known to show abnormal levels of cytokines in different ocular diseases. The aim of this study is to evaluate the expression of matrix metalloproteinases(MMP)2 and 9, in tear samples of patients with various forms of glaucoma and correlated with the severity of fibrillar material deposits.
Methods :
Tears were collected from outer canthus of patients with primary open angle glaucoma, POAG (n=12), angle closure glaucoma, PACG (n=12), pseudoexfoliation syndrome, PXF,(no disc field changes, n=12), exfoliation glaucoma, PXG (n=12) and cataract/control (n=12) using Schirmer filter strip including both eyes. Dry eye, ocular surface pathology and previous laser intervention or surgery were excluded. Proteins were quantified by Bradford and then analyzed by gelatin zymography for the expression of MMP2 and 9. Zymographic gels were imaged by Bio-Rad gel documentation system. Lysis zones in every lane were compared between glaucoma and control samples, analyzed by image J software to obtain arbitary values of band intensity. Statistical significance was assessed using ANOVA and Spearman's correlation test for correlation with clinical variables.
Results :
The mean age of patients were 66±6.3 for PXF, 71±4.5 for PXG, 58±13.7 for POAG, 66±6.8 for PACG and 66±14.4 years for control (p=0.6). The MMP9 activity was highest in PXF (375±23.5 vs 227±76.1, p=0.05) and POAG (301±146.2 vs 195±52.5, p=0.02) followed by PACG (250±124.06 vs 216±67.2, p=0.4) and PXG (228±72.5 vs 192±56.3, p=0.2). The MMP2 activity was found to be high in both PXF and PXG compared to controls; PXF (109±55.9 vs 66±36.4, p=0.04), POAG (91±31.3 vs 38±19.9, p=0.1), PACG (72±19.2 vs 33±16.3, p=0.004), PXG (110±53.4 vs 44±45.5, p=0.008) (Figure 1), maximum differences were seen in patients with PXF and POAG (Figure 2). The MMP9 activity correlated with curled edges of exfoliation deposits on the lens surface (r=0.7, p=0.02) and pupillary ruff atrophy in PXG, PXF ad PACG while it did not correlate with extent of disc or field changes in any type of glaucoma.
Conclusions :
Raised MMP2 and 9 activity may serve as potential markers for tear based glaucoma screening (quantitative or semi-quantitative). Further studies are required to determine its use for prognosticating glaucoma severity.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.