Endocrine Abstracts

Introduction: Human tear is rich in cytokines, i.e. in healthy individuals it exhibits a higher ratio of cytokines to total proteins than that in the serum of the same individual. EOP related to Graves–Basedow disease is thought to develop due to elevation of serum cytokine levels and to an altered cytokine response of the intra- and periorbital tissues. In our present study we focused on the measurement of IL6, IL8 and TNF-α, the relative amount of a lipocalin-type protein (α-1-acid glycoprotein, α-1AG or orosomucoid) in tear samples of EOP patients.

Methods: Tear was collected by the Schirmer method from 26 EOP patients and 20 control individuals without autoimmune and thyroid diseases. Eighty percent of them were females. The mean age was 45 (25–71) years. The total tear protein content was measured by the Bradford method followed by SDS-PAG electrophoresis with silver intensification (1.8 μg/lane). Tear α-1AG was detected by chemiluminescent Western blot technique. Tear cytokine levels were quantified by a chemiluminescent immunoassay method (Immulite, Beckman-Coulter).

Results: TNF-α and IL6 increased significantly in the tear samples of EOP patients (TNF-α: 513±291 vs 217±124 pg/mg, IL6: 39±31 vs 12±5 pg/mg, EOP patients versus control individuals, respectively). IL8 and α-1AG levels did not differ significantly between the two groups.

Conclusions: The content of some cytokines in the tear of EOP patients is different from that measured in healthy individuals. Increased tear TNF-α (having a primary role in the regulation of immune cells) and IL6 levels (an interleukin that acts as both a pro-inflammatory and anti-inflammatory cytokine secreted by T cells and macrophages) are considered to be a new finding in EOP patients. Mass spectrometric identification of some tear proteins is in progress to answer the question if tear as a non-invasive sample might be used for monitoring disease activity and/or effectiveness of treatment in EOP.