Dry Eye Tears Show Higher Cytokine Levels of Innate, Adaptive Immune Responses

Tears of patients with dry eye disease have higher cytokine levels of the innate and adaptive immune responses compared with healthy tears, according to research presented at the American Academy of Optometry 2022 annual meeting, held in San Diego, CA, from October 26 to October 29, 2022.  

Study authors collected tear samples from 60 participants — 30 with dry eye disease (group 1) and 30 without (group 2). The researchers used Schirmer’s test strips to collect tear samples from both eyes. Participants qualified for group 1 if they had Schirmer test scores (STS) of 5 mm or lower in at least 1 eye and an Eye Dryness Score (EDS) of 60 or lower, as measured via visual analogue scale. 

The research team analyzed tears for the presence of 9 cytokines: interleukin (IL)-2, IL-4, IL-6, IL-10, interferon-gamma (INF-γ), tumor necrosis factor (TNF), IL-1beta (1β), IL-12p70, and IL-17a. They assessed cytokine protein levels from individual tear samples using a validated multiplex bead-based immunoassay. They compared cytokine levels in group 1 and 2 using the Wilcoxon Rank Sum test.

Participants with dry eye disease exhibit differential expression of pro and anti-inflammatory cytokines compared with healthy tears, according to the presenters, led by Selina McGee, OD. Baseline (BL) STS were 4.6 mm and 19.8 mm and BL EDS were 73.5 mm and 2.5 mm for participants with dry eyes and healthy eyes, respectively, the report shows. Compared with healthy eyes, the expression profiles of IL-2, IL-4, IL-1β, IL-12p70, IL-17a, and IFN-γ and TNF were significantly (one-sided P <.05) increased in tear samples of participants with dry eyes.

“Tears of dry eye disease patients have increased cytokine levels of both the innate and adaptive immune responses as compared to healthy tears,” according to the presentation. “These findings suggest broad spectrum therapeutics should be leveraged instead of treating a specific pro-inflammatory cytokine.  The variability of cytokines observed in this study is likely due to the complexity, severity and duration of dry eye disease in any single subject.”