Altered tear composition in smokers and patients with graves ophthalmopathy

To analyze, compare, and contrast tear composition in healthy nonsmokers, smokers who were otherwise healthy, and patients with Graves disease (GD) accompanied by Graves ophthalmopathy (GO) of varying severity.

Reflex tears were collected using Schirmer strips from 37 healthy nonsmokers, 33 otherwise healthy smokers, 51 patients with GD, and 85 patients with GO. Thyrotropin receptor-stimulating activity and serum thyroid-stimulating antibodies were measured. Pooled tear samples from healthy nonsmokers, healthy smokers, and patients with GO were separated by means of electrophoresis. Proteins expressed in healthy smokers, patients with GO, and healthy nonsmokers were separated by means of electrophoresis and analyzed by mass spectrometry.

Based on the 97th percentile of findings from healthy nonsmokers, specific thyrotropin receptor-stimulating activity was detected in 25% of the tear samples from healthy smokers, 32% of those from patients with GD, and 41% of those from patients with GO. Clinical activity scores correlated with serum thyroid-stimulating antibody levels but not tear thyrotropin receptor-stimulating activity. Electrophoresis revealed additional proteins of 30 to 41 kDa in the tear samples from patients with GO and healthy smokers compared with samples from healthy nonsmokers. These proteins were identified as zinc-alpha2-glycoprotein and lactoferrin but have no thyrotropin receptor-stimulating activity.

We demonstrate similar changes in tear composition in patients with GO and healthy smokers compared with healthy nonsmokers. Expression of zinc-alpha2-glycoprotein and lactoferrin is increased and their molecular weights are modified, suggesting degradation and/or changes during glycosylation, which may affect the bioactivities of zinc-alpha2-glycoprotein and lactoferrin. Clinical Relevance Smoking, which is a significant risk factor for the development of GO, modifies tear composition.