MUC1 expression in Sjogren's syndrome, KCS, and control subjects.

PURPOSE: To quantify and compare human mucin 1 (MUC1) protein and mRNA expression in tears and conjunctival epithelial cells collected from Sjogren's syndrome (SS), non-Sjogren's keratoconjunctivitus sicca (KCS) and non-dry eyed (NDE) control subjects. METHODS: Seventy-six subjects were recruited for this study: 25 SS (confirmed via American-European Consensus Criteria 2002), 25 KCS (confirmed by symptoms and Schirmer scores < or = 10 mm) and 26 NDE. Tears were collected using an eye-wash technique. Impression cytology was used to gather protein and mRNA from conjunctival epithelial cells. Soluble and membrane bound MUC1 were quantified via western blotting and MUC1 mRNA was quantified by real time qPCR. RESULTS: The SS group demonstrated significantly higher concentrations of soluble MUC1 (0.12 +/- 0.11 [SS]; 0.013 +/- 0.02 [KCS; p=0.001]; 0.0023 +/- 0.0024 [NDE; p<0.001]) and MUC1 mRNA (3.18 +/- 1.44 [SS]; 1.79 +/- 1.18 [KCS; p<0.05]; 1.60 +/- 0.74 [NDE; p<0.05]) compared to both KCS and NDE groups. Soluble MUC1 expression was also higher in the KCS group compared to the NDE group (p=0.02), where as MUC1 mRNA expression was similar in both KCS and NDE groups. Membrane bound MUC1 expression differed only between the SS and NDE groups (0.005 +/- -0.003 [SS]; 0.003 +/- 0.002 [NDE; p=0.002]). CONCLUSIONS: These results demonstrate that SS subjects express greater quantities of MUC1 protein and mRNA compared to both KCS and control subjects. Increased soluble MUC1 expression was also found in KCS subjects compared to controls. Membrane bound MUC1 was present in higher concentration in SS versus NDE only. These significant changes in MUC1 expression may represent compensatory or protective responses to chronic insult to the ocular surface.

Tear lipocalin and lysozyme in Sjögren and non-Sjögren dry eye.

PURPOSE: To evaluate the concentration of tear lipocalin, lysozyme, and total protein in Sjögren's Syndrome (SS), non-Sjögren's keratoconjunctivitis sicca (KCS), and non-dry-eyed (NDE) individuals. METHODS: Seventy-six subjects were recruited for this study: 25 SS subjects; 25 KCS subjects, and 26 NDE individuals. Symptoms were measured with a visual analogue scale. Tear flow was measured by the Schirmer I test without anesthesia. Tears were collected using an eye wash technique. Total tear protein was quantified using the DC Protein Assay Kit. Tear lipocalin and lysozyme were quantified via Western blotting performed on a Phast System. RESULTS: By definition, the SS and KCS groups both had significantly lower mean Schirmer scores (5.12 +/- 5.96 mm and 7.84 +/- 7.35 mm) compared with the NDE group (23.83 +/- 7.85 mm; p < 0.0001). There was no difference in mean Schirmer scores between SS and KCS groups (p = 0.19). The tear film of the SS group was characterized by significantly reduced (p < 0.0001) total protein and lipocalin concentrations compared with both KCS and NDE groups. No difference between the KCS and NDE groups was found in total protein (p = 0.92) or lipocalin (p = 0.19) concentration. In contrast, the concentration of tear film lysozyme was found to be statistically similar in all three groups examined. No statistically significant correlation was found in any group between mean Schirmer values compared with total protein, lipocalin or lysozyme concentration. CONCLUSION: Our data demonstrate a biochemical distinction between the Sjögren's group compared with both KCS and control groups, in that both tear lipocalin and total tear protein were significantly reduced. Although correlations were not found between protein measurements and tear flow, a combination of tests including Schirmer I and quantitation of tear film biomarkers may allow for the identification of SS patients without the need for invasive testing.