Abstract
Purpose: :
Meibomian gland disease (MGD), a common condition in Asia and other parts of the world, causes symptoms of tear dysfunction and is an important predisposing factor for evaporative dry eye. Tear proteins have an important role in the maintenance of the ocular surface and reflect the health and microenvironment of the ocular surface. However, the relationship between the tear proteins and MGD (or related symptoms) has not been reported. We aim to evaluate severity of MGD with tear protein levels.
Methods: :
Twenty-four patients with dry eye have Meibomian gland disease (MGD) severity graded 0(absent)-3(severe) based on slit-lamp biomicroscopic criteria. Presence of lid margin telangiectasia was grade 1, meibomian gland orifice plugging was grade 2 and presence of both was grade 3. Tear was collected from the inferior conjunctival sac. The level of a panel of 10 tear proteins previously found important in dry eye was evaluated using iTRAQ based quantitative proteomics combined with 2D-nanoLC-nano-ESI-MS/MS.
Results: :
The mean age was 35.5 years (SD: 15.4). with 15 women and 9 men. Nine (37.5%), 8 (33.3%), 3 (12.5%) and 2 (8.3%) of patients had MGD grading of 0, 1, 2 and 3 respectively. The level of S100A8 and S100A9 (r=0.47 and 0.42 respectively) were correlated to MGD severity. Higher S100A8 level was significantly correlated to presence of grittiness whereas higher S100A8 and S100A9 were correlated to symptoms of redness and transient blurring. Lipocalin-1 was associated with heaviness of the eyelids and tearing. Lactoferrin, on the other hand, was correlated to presence of pain and tearing. α-enolase, α-1-acid glycoprotein, S100 A4, S100 A11, prolactin-inducible protein and lysozyme levels were not associated with these outcomes.
Conclusions: :
Distinct tear proteins are associated with MGD severity in dry eye patients, and some proteins were associated with frequency of symptoms of tear dysfunction. This study shows that increased MGD severity affects not only tear film lipids but also tear proteins, and has the potential to induce irritative symptoms by contributing to the inflammation in dry eye. Greater attention should be focused on assessment of MGD in any dry eye patient.
Keywords: cornea: clinical science • proteomics • inflammation