Changes in tear protein profile in patients with conjunctivochalasis

To compare the protein profiles of tears from normal volunteers and patients with conjunctivochalasis (CCH), with a view to identifying proteins whose expression is altered in this pathology.

Tears from 8 normal subjects and 6 patients with CCH were analyzed by 2-dimensional electrophoresis. Total protein from tears was separated in the first dimension by isoelectric focusing, and the second dimension was carried out using 8%-16% sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The gel images were analyzed using Progenesis SameSpot software. Those spots of interest were manually cut out from the gels, and the corresponding proteins were identified by matrix assisted laser desorption/ionization-time of flight (MALDI-TOF). Expression levels of proteins that had been found to be significantly altered were further verified by Western blot.

Approximately 250 spot proteins were detected in the whole tear proteome. Twenty-four spots were significantly upregulated in CCH compared with that in controls. Eleven protein spots were identified, which included proteins belonging to the S100 family (A8, A9, A4; 2.44, 1.71, and 2.82 fold upregulation, respectively), guanosine triphosphate-binding protein 2 (1.95 fold), l-lactate dehydrogenase A-like 6B (2.32 fold), fatty acid-binding protein (2.01 fold), keratin type I cytoskeletal 10 (1.81 fold), glutathione S-transferase P (2.27 fold), peroxiredoxin-1, peroxiredoxin-5 (1.79- and 1.92 fold, respectively), and cullin-4B+ glyceraldehyde 3-phosphate dehydrogenase (1.96 fold).

We have identified a group of proteins, which is upregulated in CCH tears. Although some of them, such as S100A4, S100A8, and peroxiredoxin-5, are markers of inflammation and oxidative processes, monitoring their levels in CCH might be useful for assessing the severity and progression of the disease.