Association of tear proteins with Meibomian gland disease and dry eye symptoms

Abstract

Aim: Tear proteins have an important role in the maintenance of the ocular surface and modulation of biological processes, including inflammation, in dry eye. Meibomian gland disease (MGD) is a condition that can increase inflammation in the ocular surface, but tear protein changes due to MGD have not been documented. This study evaluated the possible association of tear proteins with severity of MGD in dry eye. Methods: Twenty-four patients with dry eye were evaluated. The panel of proteins found previously to be of interest and evaluated in this study were α-enolase, α-1-acid glycoprotein 1, S100A8 (calgranulin A), S100A9 (calgranulin B), S100A4 and S100A11 (calgizzarin), prolactin-inducible protein (PIP), lipocalin-1, lactoferrin and lysozyme. Tear protein ratios for each of 24 patients were calculated relative to pooled control from 18 healthy people, using isobaric tagging for relative and absolute quantification (iTRAQ)-based proteomics combined with two-dimensional-nanoliquid chromatography (LC)-nano-electrospray ionisation (ESI)-mass spectrometry (MS)/MS. The severity of MGD was clinically classified into grades 0-3 based on biomicroscopic signs. Results: The levels of S100A8 and S100A9 were correlated to MGD severity. The level of S100A8 protein was significantly correlated to grittiness, whereas S100A8 and S100A9 were correlated to symptoms of redness and transient blurring. Lipocalin-1 was associated with heaviness of the eyelids and tearing. Conclusions: Distinct tear proteins are associated with MGD in dry eye patients, and some proteins were associated with distinct dry eye symptoms. These findings suggest that MGD may independently contribute to the symptomatology of dry eye patients.