Abstract
Background: Ocular and systemic autoimmune diseases induce changes in the protein profiles of tear fluid. To achieve a better understanding of the complex pathological processes in autoimmune Graves? orbitopathy (GO), more detailed information about these proteins had to be obtained. Hence, the aim of this prospective and controlled study was to detect and evaluate potential changes in the proteomic patterns in tear fluid of patients with GO.
Methods: Tear fluid was collected from 45 patients with GO and 15 healthy controls. The patients were split into three groups: untreated, previously treated, or currently receiving steroids. Their tear proteins were analyzed using SELDI-TOF-MS arrays with different chromatographic surfaces (CM10 cation exchange, H50 reversed-phase). Data was analyzed by multivariate statistical techniques and artificial neural networks. The most important biomarkers were enriched, purified and identified by MALDI-TOF-MS/MS.
Results: Discriminate analysis demonstrated marked alterations in the complex tear protein profiles of patients with various activity and severity classes of GO (p=0.00001). The most important biomarkers with the molecular weight 3808 (p=0.038) and 3837 (p=0.0074) Dalton (Da) were markedly reduced. A differentiation between tear fluid of patients with GO and healthy controls was enabled considering the biomarkers at the molecular weight 5087 Da (p=0.025) and 12003 Da (p=0.030). Biomarkers at 11770 Da (p=0.0022) and 3348 Da (p=0.032) increased either after or during treatment, and could therefore be used as follow-up parameters.
Conclusions: The SELDI-TOF-MS is an ideal tool for the screening of proteins in tears. The proteins found could serve as biomarkers for diagnosis of the disease as well as for follow-up during treatment. To estimate the role of these proteins in the pathological processes related with GO and establish them in the clinical routine, further analysis and identification of these proteins are warranted.