Conjunctival epithelial cell HLA-DR expression and association with signs and symptoms of Dry Eye Disease (DED) in the ‘Dry Eye Assessment and Management’ (DREAM^©) Study.

Abstract

Purpose : Although DED has a high prevalence (8-50% in adults worldwide), diagnosis and evaluation of severity is often subjective, typically based on signs and symptoms. Minimally invasive biomarkers with objective metrics may provide an alternative method for diagnosis and evaluation of severity. We determined the relative expression of an inflammatory biomarker, HLA-DR, by conjunctival cells and assessed its association with DED signs and symptoms at baseline among patients recruited for the DREAM^© study.

Methods : At baseline, patients underwent evaluation for DED signs and symptoms including: (1) Ocular Surface Disease Index (OSDI), (2) Brief Ocular Discomfort Inventory (BODI), (3) Tear Volume (Schirmers strip), (4) Tear Breakup Time (TBUT) and (5) Corneal and Conjunctival Staining. Impression cytology samples of conjunctival cells from each eye were collected and evaluated for HLA-DR by flow cytometry following a well-established SOP. HLA-DR-positive epithelial cells were identified by co-expression with EpCAM. The % of epithelial cells expressing HLA-DR was grouped into <5%, 5-15%, >15-25% and >25%. The associations of % HLA-DR with DED signs and symptoms were evaluated using analysis of variance and a linear trend test that accounted for the inter-eye correlation using generalized estimating equations.

Results : Among 521of 535 DREAM^© patients with conjunctival cell samples, 81.2% were females and the mean±SD age was 58.2±13.1yrs, ranging from 18-87yrs. Among 1037 eyes with epithelial cell counts>1000, the mean±SD% of epithelial cells expressing HLA-DR was 12.6±18.6% ranging from 0%-96.2% and 50% (534 eyes) of the samples had > 5% of epithelial cells expressing HLA-DR. Among assessed signs (Table 1) and symptoms (Table 2), higher % HLA-DR was significantly associated only with higher conjunctival staining score (p=0.02).

Conclusions : The distribution of % HLA-DR expressing epithelial cells was wide-ranging and showed association with conjunctival staining score. HLA-DR may best describe a sub-group of DED patients rather than grade severity of all DED. It also remains to be seen how HLA-DR expression correlates to other inflammatory biomarkers assessed as part of the DREAM^© study.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.