Abstract
Purpose: :
Previous studies could reveal differentially expressed factors, e.g. complement proteins, heatshockproteins and cytokines, in the tears of patients with different ocular disorders. The aim of this study was to perform a proteomic analysis in tear fluid of patients with epiretinal gliosis (eG), diabetic retinopathy (dR), macular pucker (Mp) and age-related macular degeneration (AMD), using a customized antibody microarray approach, in order to provide insights into factors and mechanisms responsible for these diseases, and to detect possible biomarkers for diagnosis.
Methods: :
Tears of patients with eG (n=16), dR (n=8), Mp (n=12), AMD (n=3), and healthy subjects (CTRL; n=24) were evaluated. For protein analysis we used antibody-microarrays, which were prepared by spotting 46 different antibodies, mainly against complement proteins, heatshockproteins and cytokines, onto nitrocellulose-coated slides. For visualization of the antibody-antigen-reactions the tear proteins were eluted from Schirmer strips, labeled with a fluorescent tag (Cy 5) and 5 µg tear proteins were incubated with antibody arrays. The signals emitted from the bound proteins were digitized and the spot intensities were compared using statistical techniques such as ANOVA and Post-hoc.
Results: :
Strong alterations in protein expression profiles could be found in tear fluids of patients suffering from different ocular disorders. Patients with dR showed a 2.5-fold increased expression of INF-gamma in comparison to CTRL (p=0.000199) and differ significantly from all other groups (p < 0.05). AMD patients vs. CTRL exhibit a 2.1-fold increase in hemopexin expression (p=0.012250), whereas patients suffering from Mp express less hemopexin than CTRL. Additionally, eG patients revealed ~1.5 fold increased expression of complement C8 vs. CTRL, and show together with dR patients a trend toward elevated expression of complement proteins.
Conclusions: :
Our study demonstrates that changes in tear protein expression patterns can be found in patients with various ocular diseases using antibody microarray technique. This might be useful to identify biomarkers for the different ocular disorders and could lead to a new innovative method for diagnosis.