Exploration of human tear proteome

Abstract

PurposeThe tear film is a complex structure which constitutes an interface between our eyes and the external environment. Its protein, lipid and metabolite composition is highly regulated depending on several factors. Despite its attractive characteristics, this fluid is still poorly studied. Here we present an in‐depth human tear proteome based on a mass spectrometry approach.MethodsIn this study, tears of two healthy controls (two women aged 59 and 61 years) were collected with Schirmer's papers. After trypsin digestion and off‐gel electrophoresis fractionation, two proteomic analyses were performed by mass spectrometry (using LTQ Orbitrap Velos Pro coupled to a liquid chromatography). Resulting files were searched against the UniProt‐SwissProt/TrEMBL database (version 2014_10) and a false discovery rate of 1% was selected. The protein list was analysed using Ingenuity Pathways Analysis and Cytoscape software.ResultsGlobally 2105 and 825 proteins were identified with 1 and 2 unique peptides respectively after removing keratins and immunoglobulins. Regarding the 825 proteins, the top three pathways that we highlighted were the acute phase response signalling, the remodelling of epithelial adherens junctions and the clathrin‐mediated endocytosis signalling. Moreover, we identified 203 proteins that were not found in the previous published studies. By comparing our tears with others fluids, only 26.9% were identified in vitreous humor and 45.7% in plasma, confirming that tears have a specific composition.ConclusionsThanks to this study, we are able to propose an expanded tear proteome. Both specific proteins of the tears and correlations with other fluids give them a great potential for biomarker research.This study is kindly supported by the Provisu Foundation and the SNF_MVH (PMPDP3_158370).