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Maria C Edman, Srikanth Reddy Janga, Alexander F Chen, Mercy Bechtold, Alice Kim, poysophon poysophon, Wendy J Mack, William Stohl, Sarah F Hamm-Alvarez; Four tear biomarkers distinguish Sjögren’s Syndrome patients from patients with other autoimmune diseases. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):2483. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Sjögren’s syndrome (SS) is an autoimmune disease (AD) that commonly affects the lacrimal gland and leads to dry eyes. Among patients with dry eyes, differentiating patients with SS from those with other AD or non-AD can be challenging. We recently identified elevated tear cathepsin S (CTSS) activity as a promising candidate biomarker for distinguishing SS patients from those with non-SS AD and non-AD, and we herein evaluate CTSS and three additional tear proteins, secretory IgA (sIgA), lactoferrin (LF), and cystatin C (CysC) in SS patients compared to patients with rheumatoid arthritis (RA) or other non-SS AD
Female patients with primary or secondary SS (n=28, age 52±1 yrs), RA (n=27, age 51±2 yrs), or other AD (OAD) (n=18, age 45±2 yrs) were recruited. An anesthetized Schirmer's test was performed on both eyes of each patient, and tear proteins were eluted and analyzed within 4 hours for CTSS activity and sIgA, LF, and CysC concentrations using commercial kits. All values were normalized to total tear protein concentration. Statistical analysis was performed using one-way ANOVA followed by Bartlett’s test for equal variance and Tukey’s multiple comparison test, and p ≤ 0.05 was considered significant.
Tear CTSS activity was significantly greater in SS than in RA (4-fold) or in OAD (8-fold) (SS: 6861±1026, RA: 1826±287, OAD: 895±136 U/µg). Levels of sIgA and CysC were each 3-fold lower in SS than in RA or OAD (sIgA, SS: 405±70, RA: 1222±140, OAD: 1152±145 µg/mL) (CysC, SS 305±40, RA, 944±151, OAD 1048±135 ng/mL), and levels of LF were 3-fold lower in SS than in RA and 4-fold lower than in OAD (SS: 360±61, RA: 917±92, AD: 1543±154 µg/mL). There were no significant differences in CTSS, sIgA and CysC between RA and other OAD, although LF was significantly lower in RA than in OAD.
Compared to patients with RA or OAD, SS patients harbor greater tear levels of CTSS activity but lower levels of sIgA, LF and CysC. These tear proteins may serve as biomarkers and facilitate earlier diagnosis of SS, thereby enabling more effective treatment of its ocular pathology.
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