Abstract
Purpose :
Characterization of the normal human tear film proteome presents many challenges, including the accurate collection of a small amount of basal tears present in the normal tear reservoir while minimizing reflex tearing. To compensate for small sample volumes, sample pooling across subjects is frequently reported, which precludes analysis of individual variation in the tear proteome. In the present study, we characterized the normal human tear film proteome in genetically related female family members across three generations, all born and raised within the same geographical region.
Methods :
This was a single center cross-sectional study. Four genetically related females spanning three generations were assessed through clinical history, slit-lamp examination, and dry eye testing for the presence of underlying anterior segment disease. Tear fluid was collected from both the right and left eyes using glass micro-capillary tubes over a series of multiple visits. For each participant, samples from repeat visits were pooled. Total protein was measured using a bicinchoninic assay. 215 µg of total protein from each sample was separated by SDS-PAGE, individual lanes were then fractionated and analyzed by mass spectrometry. Identified proteins were classified using PANTHER (Protein ANalysis THrough Evolutionary Relationships) and functional enrichment analysis was further analyzed using the WEB-based GEne SeT AnaLysis Toolkit.
Results :
Tear protein concentration for all subjects was 9.2 ± 2.2 µg/µl. Over 400 unique tear film proteins were identified with 290 common proteins found across all three generations. The largest difference in protein composition was found in the oldest generation, which had 54 unique proteins consistent with the enrichment of multiple inflammatory pathways associated with advanced age.
Conclusions :
This is the first multi-generational study characterizing the normal tear film proteome. The use of a multi-generational study design minimizes the genetic and environmental variation that may influence protein composition and provides a clear picture of the proteins that are conserved across individuals. The data acquired in this study will serve as a sensitive platform for future large-scale studies aimed at identifying novel tear film-derived biomarkers associated with both ocular and systemic disease.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.