Investigation of the global protein content from healthy human tears

Abstract

Considering absence of invasiveness and side effects, tears emerge as a particularly attractive fluid for biomarker discovery and therefore for daily clinical use. However, to date, this fluid remains poorly studied in healthy condition. Here, we present an updated in-depth characterisation of the human healthy tear protein composition using proteomics approach. Both eyes of eight healthy controls were collected using the Schirmer's strip method. After liquid digestion and off-gel electrophoresis fractionation, three independent proteomics analyses were performed. Resulting files were searched against the uniprot_swissprot database (2017_05_10) using Thermo Proteome Discoverer (version 2.2) and a false discovery rate of 1% was selected. Globally, 1351 proteins were identified with 2 unique peptides. More specifically, 39% of the lacrimal proteins were enzymes, with high numbers of dehydrogenases, phosphatases, kinases and ligases. Immunoglobulins, serpins and 14-3-3 domains proteins emerged also as abundant lacrimal proteins. Pathway analyses highlighted among others the glycolysis and the coagulation and complement cascades. Our study therefore complements the existing data on healthy tears proteome. Nevertheless, extensive studies for deeply and definitively characterise this promising fluid are required in the near future in order to be able to routinely use this fluid in clinics. A better understanding of its protein content will probably open new avenues in the biomarker discovery and clinical practice in the near future.

Comparative analysis of the tear protein profile in herpes simplex virus type 1 epithelial keratitis

“…As expected, highly abundant proteins such as lactotransferrin, lipocalin 1, lipocalin 2, albumin, lysozyme, complement C3, and immunoglobulin heavy constant alpha 1 were present in tears of individuals from both groups. Most of these proteins are involved in inflammatory and antimicrobial processes, and play an important role in maintaining a clean ocular environment [ 22 ]. In the three HSV-1 epithelial keratitis patients, 597, 595, and 551 proteins were identified, respectively, while 351 (43.5%) proteins were identified in all three patients (Fig.…”

Recent advances in mass spectrometry based clinical proteomics: applications to cancer research

“…Tears provide an intriguing biomarker source and only recently have there been efforts to characterize its proteome [16]. Tears from both eyes of eight healthy controls were analyzed and unsurprisingly, a significant proportion of the identified proteins were enzymes [201]. Similarly to urine, a subset of tear protein expressions have been reported to correlate with age [202].…”

Proteomic Study of Aqueous Humor and Its Application in the Treatment of Neovascular Glaucoma

“…As an important component of the innate defense system of the eye, tear provides protection against a range of potential pathogens. In order to analyze the function of different ocular fluids, the investigators compared the whole human AH data with vitreous humor (Murthy et al, 2014) and tear (Dor et al, 2019) from other ocular proteomic studies.…”