Association of Tear Cytokine Ratios with Symptoms and Signs of Dry Eye Disease: Biomarker Data from the Dry Eye Assessment and Management Study

Longitudinal Analysis of Tear Cytokine Ratios in Association with Dry Eye Signs and Symptoms in the Dry Eye Assessment and Management (DREAM) Study

PURPOSE

To extend cross-sectional data on cytokine ratios (CRs) in dry eye disease (DED) signs by investigating longitudinal change in pro- to anti-inflammatory CRs and associations with change in DED signs and symptoms.

METHODS

Secondary analysis of fifty-four subjects [mean age 57.3 (SD 13.2) years, 85.2% female; 68.5% white] with ≥ 4 uL pooled tear volumes at months 0, 6, and 12. Pro-inflammatory (IL-1b, IL-6, IL-8, IL-17A, IFN-g, and TNF-a) to anti-inflammatory (IL-6, IL-10) cytokine ratios (CR) were calculated. DED signs (corneal and conjunctival staining scores, tear break-up time, Schirmer test, Meibomian gland plugging, tear osmolarity, composite sign severity score) and symptoms [Ocular Surface Disease Index (OSDI)] were measured. Changes over time in DED signs, symptoms, and CRs were evaluated using longitudinal models. Correlations between changes in CR and changes in DED signs and symptoms were evaluated using Spearman correlation coefficients (rho).

RESULTS

DED signs which improved over time (p < 0.001) included corneal and conjunctival staining score, tear break-up time, tear osmolarity, and composite sign severity score. Using IL-10 as anti-inflammatory, changes in corneal and conjunctival staining and composite severity score significantly correlated with changes in pro- to anti-inflammatory CRs from month 0 to 6 (|rho|: 0.29-0.45, p: 0.003-0.04) but not between month 0 to 12 (|rho|: 0.01 to 0.24, all p > 0.08). DED symptoms decreased across one year (p < = 0.001) for all OSDI measures; these changes did not correlate with changes in CRs (|rho|: 0.00 to 0.29, all p > 0.04).

CONCLUSIONS

Improvement in some DED signs across one year correlated weakly with decreases in pro- to anti-inflammatory CRs, in alignment with the understanding of DED as inflammatory. CRs may provide greater insight than absolute tear cytokine concentrations as possible DED biomarkers. Additional studies that provide standardized clinical information and tear collection and analysis are needed to validate CRs in DED.

Inflammation mechanism and anti-inflammatory therapy of dry eye

Dry eye is a widespread chronic inflammatory disease that causes fatigue, tingling, burning, and other symptoms. Dry eye is attributed to rheumatic diseases, diabetes, hormone disorders, and contact lenses, which activate inflammatory pathways: mitogen-activated protein kinases (MAPK) and nuclear factor-B (NF-κB), promote macrophage inflammatory cell and T cell activation, and inflammation factors. Clinicians use a combination of anti-inflammatory drugs to manage different symptoms of dry eye; some of these anti-inflammatory drugs are being developed. This review introduces the dry eye inflammation mechanisms and the involved inflammatory factors. We also elucidate the anti-inflammatory drug mechanism and the detection limits.