The tear cytokine profile in patients with active Graves' orbitopathy

The primary aim of this study is to isolate cytokines specific for active Graves' orbitopathy (GO) in the tears of affected patients. The secondary aim is to identify other cytokines of interest and to look at the profile of their levels over time.

This is a prospective pilot study conducted at the Singapore National Eye Centre. A total of 10 patients with active GO and 10 patients from each of 3 control groups were recruited. The 3 control groups were the following: age-matched normal female patients, patients with GO who were clinically inactive and patients with bilateral viral conjunctivitis. Tears from patients from the control groups were collected on a single visit. For patients with active GO, tears were collected on presentation, at 6 months, 12 months and 18 months.

Of all the cytokines examined, only IL-7 yielded a difference when the concentration in patients with active GO was compared with concentrations in all the control groups. This difference was most significant at the 18-month follow-up visit.

Low concentrations of IL-7 in tears exhibit specificity for active GO in patients nearly 2 years from the clinical onset of activity. Although using IL-7 in tears as a biomarker for disease activity may be limited due to its late manifestation, targeting immune restitution using IL-7 may have disease modifying effects.