Abstract
Purpose:
To determine levels of matrix metalloproteinases (MMPs), tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) and inflammatory marker myeloperoxidase (MPO) in the tears of patients with ocular cicatricial pemphigoid (OCP) and Stevens-Johnson syndrome (SJS).
Methods:
Tears were collected from 7 SJS, 38 OCP and 40 post-cataract (control) eyes. 60μL of sterile balanced salt solution was instilled on each eye and tears washes were recovered with a micropipette. The tear concentrations of MMP-2, -3, -7, -8, -9 and -12 (ng/mL) in each eye were measured using a Fluorokine® Human MMP MultiAnalyte Profiling (MAP) Kit. TIMP-1 and MPO concentrations (ng/mL) were measured using a Fluorokine® human Cardiac B MAP Kit. Both assays were run on a Bio-Rad Bio-Plex analyzer powered by Luminex® technology. Total MMP activity was measured fluorometrically using an OmniMMP™ RED fluorogenic substrate. Values for all assays were standardized to the protein mass loaded in each assay.
Results:
The concentrations (ng/μg total protein) of MMP-8, -9 and MPO were statistically higher in tears of patients with SJS (4.3 ± 2.0, 10.2 ± 4.5 and 6.7 ± 2.0, respectively) than in OCP (0.4 ± 0.2, 0.9 ± 0.4 and 1.5 ± 0.4, respectively), and both were significantly higher than in control (0.01 ± 0.003, 0.06 ± 0.01 and 0.4 ± 0.1, respectively). The ratio of MMP-8/TIMP-1 and MMP-9/TIMP-1 were statistically higher in SJS (7.4 ± 3.4 and 16.2 ± 6.6, respectively) than in OCP (1.1 ± 0.6 and 4.6 ± 2.5, respectively) and both were significantly higher than in control (0.01 ± 0.003 and 0.05 ± 0.01, respectively). The total MMP specific activity (RFU/min/μg protein) was higher in SJS (25.02 ± 10.60) than in both OCP (4.75 ± 2.73) and control (1.25 ± 0.87). Spearman rank correlation tests showed significant correlations between MMP-8 and MMP-9, and between MMP-9 and MPO across all groups. MMP-8 correlated with MPO in control and OCP patients (p < 0.0001), and to a lesser extent with SJS (p = 0.066).
Conclusions:
Since activated neutrophils are known to be a source of MMP-8, -9 and MPO, the high levels of these enzymes in the tears of SJS and OCP patients and the strong correlation between MMP-8, MMP-9 with MPO suggest that inflammatory cells are the primary source of the elevated enzymes. In addition to MMP-8 and MMP-9, MPO was found to be a marker of inflammatory ocular surface disease.
Keywords: 479 cornea: clinical science •
486 cornea: tears/tear film/dry eye •
514 enzymes/enzyme inhibitors