Purpose
Muc-16 is one of the primary membrane-associated mucins that form the protective glycocalix on the ocular surface. Previous studies have shown that the extracellular domain of this glycoprotein is cleaved and released in the tear film of dry eye patients. Cleavage of Muc-16 has also been demonstrated in response to local inflammation. The purpose of this study was to confirm the up-regulation of soluble Muc-16 (CA-125) in the tear film of dry eye patients, and explore any correlations with the clinical signs of dry eye.
Methods
Tears from a total of 49 eyes from 34 subjects were collected and included in the analysis (8 normal and 26 dry eye). A commercially available Muc-16 (CA-125) ELISA kit was used to quantify the amount of Muc-16 in each sample. Muc-16 levels in each tear sample were normalized to the total protein concentration determined for each sample. Clinical endpoints including Schirmer’s test, fluorescein staining, and tear film breakup time (TFBUT) were assessed for both dry eye and normal patients.
Results
Muc-16 values were calculated in terms of Muc-16 units (U) per microgram (µg) of total protein in a given tear sample. There was a statistically significant inverse correlation between Muc-16 and Shirmer’s and TFBUT for all subjects. Total staining, corneal staining, and conjunctival staining showed statistically significant positive correlations with Muc-16 for all subjects.
Conclusions
The results of this study conclude that as the signs of dry eye worsen, soluble Muc-16 values increase. Additional studies are required to confirm this hypothesis and should ensure that equal numbers of age-matched males and females are sampled that are both symptomatic and asymptomatic for dry eye.
Keywords: 486 cornea: tears/tear film/dry eye •
557 inflammation •
479 cornea: clinical science