Abstract
Differentiating patients with Sjögren's syndrome (SS)-associated dry eye from non-SS dry eye is critical for monitoring and appropriate management of possible sight- or life-threatening extraglandular complications associated with SS. We tested whether reduced tear levels of immunoregulatory thrombospondin (TSP)-1, which also inhibits matrix metalloproteinase (MMP)-9, would reflect SS pathogenesis aiding the identification of patients with SS-dry eye. Total of 61 participants, including healthy controls (n = 20), patients with non-SS dry eye (n = 20) and SS-dry eye (n = 21) were enrolled prospectively. Tear TSP-1 and MMP-9 levels were measured using a custom magnetic bead-based multi-plex assay in a masked manner. Analyte concentrations were assessed further according to ocular surface and tear film parameters. Relative to median tear TSP-1 (308 ng/ml) and MMP-9 (1.9 ng/ml) levels in the control group, significantly higher proportion of patients with SS-dry eye than non-SS had lower tear TSP-1 levels (55% vs. 29%, odds ratio [OR] = 3, 95% confidence interval [CI] = 1.64 to 5.35, p < 0.05) and higher tear MMP-9 levels (65% vs. 24%, OR = 5.8, 95% CI = 4.46 to 19.81, p < 0.05), respectively. The tear TSP-1/MMP-9 ratio was significantly reduced in patients with SS-dry eye compared to non-SS (B = -2.36, 95% CI = -3.94 to -0.0.79, p < 0.05), regardless of tear MMP-9 levels. Patients with a lower ratio were 2.3 times more likely to have SS (OR = 0.28, 95% CI = 0.1 to 0.75, p < 0.05). This ratio showed significant inverse correlations with clinical parameters (conjunctival and corneal staining scores). Our results denote that tear TSP-1/MMP-9 ratio can be useful in identifying patients with dry eye with underlying SS and used as a screening test.