Purpose
From dry eye (DE) clinical studies, it is recognized that signs and symptoms are not well correlated. Flow cytometric HLA-DR analysis of conjunctival imprints (CI) was used to assess ocular surface inflammation in many clinical studies. Here, we retrospectively analyzed correlations between clinical signs and symptoms, and conjunctival HLA-DR in 3 phase III clinical studies conducted on moderate to severe DE-patients in several European countries.
Methods
Demographic and baseline DE characteristics were analyzed (mainly, corneal fluorescein staining (CFS), Schirmer test, tear break‑up time (TBUT), tear osmolarity, Ocular Surface Disease Index (OSDI®) and Visual Analog Scale (VAS) scores). CI were collected from 311 patients using a polyether-sulfone filter. After extraction and dispersion in fluid, cells were stained with an anti-human HLA-DR alpha-chain (Dako) and HLA-DR fluorescence was quantified using QIFIKIT (Dako) calibrated beads in arbitrary units of fluorescence (AUF).
Results
In DE-patients, HLA-DR significantly increased in Sjögren’s syndrome (p<0.0001) and meibomian gland disease (p=0.0223). HLA-DR AUF was correlated positively with CFS (r=0.30, p<0.0001) and negatively with Schirmer test (r=-0.20, p=0.0003) and TBUT (r=-0.13, p=0.0226). Moreover, correlations were also found significant with the OSDI® and the VAS scores (r=0.12, p=0.0426 and r=0.14, p=0.0176, respectively). HLA‑DR AUF and osmolarity were not correlated (r=0.08, p=0.4987).
Conclusions
In clinical research on dry eye, the lack of correlations between symptoms and signs sometimes observed makes data interpretation somewhat complicated. Here we demonstrated for the first time that the inflammatory marker HLA-DR assessed using a flow cytometry method correlated significantly with the clinical signs (CFS, Schirmer test and TBUT) and with the symptom questionnaires. HLA DR used for about 20 years to assess ocular surface inflammation could be considered today as a surrogate biomarker bridging signs and symptoms in clinical investigations of dry eye disease.