Abstract
Purpose: :
To measure matrix metalloproteinase (MMP)-9 activity in tears of patients with dysfunctional tear syndrome (DTS). The correlation between MMP-9 activity and clinical parameters of DTS was also evaluated.
Methods: :
One microliter of unstimulated tear fluid was collected from 20 patients with newly diagnosed DTS and 12 asymptomatic control subjects. MMP-9 activity was assessed with a Biotrack MMP-9 activity assay system. Dry eye symptom questionnaire and complete ocular surface examination were performed. Levels of MMP-9 mRNA transcripts in conjunctival epithelia (5 DTS patients and 5 asymptomatic control subjects) obtained by impression cytology were evaluated by real time PCR.
Results: :
The patients were classified into DTS with lid margin disease, all of which had meibomian gland disease (MGD) and DTS without lid margin disease, all of which had aqueous tear deficiency (ATD). The MMP-9 activities were 31.06 + 32.37 ng/ml in control tears, 103.90 + 99.93 ng/ml in the DTS MGD group and 438.18+ 238.40 ng/ml in the DTS ATD group (P <0.006 versus DTS MGD and control). MMP-9 activities showed significant and positive correlation with symptom severity scores (r2 0.245, P 0.005), corneal fluorescien staining score (r2 0.638, P <0.001), conjunctival fluorescien staining score (r2 0.450, P <0.001) and negative correlation with fluorescien tear break up time (r2 0.217, P 0.008). The preliminary results evaluating conjunctiva demonstrated that DTS patients had higher levels of MMP-9 mRNA transcripts than control subjects (P 0.006).
Conclusions: :
MMP-9 activity, which was highest in DTS with ATD, correlated well with parameters of disease severity. The measurement of tear MMP-9 activity may be clinically useful for diagnosing and monitoring DTS.
Keywords: cornea: tears/tear film/dry eye • cytokines/chemokines • clinical research methodology