Objective: To explore the differential expressions of lysozyme C and lactoferrin in tears of thyroid-associated ophthalmopathy (TAO) patients versus healthy subjects by proteomics.
Methods: Tear samples were obtained from patients with active period TAO and age and gender-matched healthy subjects without symptoms of ocular surface. Then they were divided into patient and control groups. Then tear samples of two groups were analyzed. sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of 15% gel was performed to determine the different protein bands in sample groups. And different labeled protein bands were collected for in-gel tryptic digestion. Mass spectrometry was employed to determine the protein components from different protein bands. Then Scaffold search engine was used for analyzing the results of mass spectrometry and identifying specific proteins.
Results: Based on mass spectrometric analysis of different protein bands, most proteins were down-regulated or became absent in TAO patients. Both lysozyme C and lactoferrin were up-regulated. Identification of protein relative quantitative ratio (patient/control): lysozyme C: 4.88, lactoferrin: 1.61.
Conclusions: Lysozyme C and lactoferrin are two important effectors of tear function and metabolism. Both are up-regulated in TAO patients' tears. Thus both are probably involved in inflammatory process of TAO and play synergistic roles in the pathogenesis of disease.