Background/Purpose: Children with juvenile idiopathic arthritis (JIA) are at risk for anterior uveitis which can lead to ocular complications and vision loss.  The ANA is the only biomarker that guides the schedule of uveitis screening, but it is not definitive.  Potential biomarkers have been identified in the serum and aqueous humor of children with JIA-associated uveitis (JIAU) and idiopathic uveitis. However, few studies have examined protein levels in the tears of children with chronic anterior idiopathic uveitis (CAU) and JIA-associated uveitis (JIAU).  Tear collection is non-invasive, easily accessible and better tolerated by children. Our aim is determine if we can identify biomarkers using tear proteomics in children with anterior uveitis.  

Methods: We collected tear samples from 2 pediatric female controls, 2 JIAU (oligoarticular) and 2 CAU. Children with uveitis were ≥10 years old, non-Hispanic, female, and had anterior involvement. We placed a Schirmer strip 6mm from the lateral canthus of the anesthetized eye for 2-5 minutes.  Then, 50 ug of proteins were extracted for TMT labeling.  The TMT pool was loaded onto an offline electrostatic repulsion interaction chromatography (ERLIC) fractionation HPLC system and 20 fractions were collected. LC-MS/MS analysis was then performed on all 20 fractions. Proteome Discoverer 2.1 (ThermoFisher Scientific, San Jose, CA) was used to search all the MS/MS spectra against a Uniprot human reference protein database (retrieved April 20, 2015; 90,411 target sequences) and TMT reporter quantitation was performed. We compared JIAU and IU to controls, and JIAU to IU using ANOVA statistics.

Results:   In all, we were able to quantify 1224 unique protein groups and found 120 proteins that showed significant statistical changes.  Of those differentially expressed proteins, 19 were significant across JIAU versus control and IU versus control, but not between JIAU and IU. The most significant included RAB7A (p = 1.23E-03), NPC2 (p = 1.23E-02), VPS4B (p = 3.05E-03), CTSS (p = 2.02E-02), and ASAH1 (p = 1.19E-02).  The gene ontology showed cellular component enrichment for lytic vacuole and biological pathway enrichment for sterol transport and transmembrane receptor signaling.

Conclusion: In our pilot study, we identified proteins that may be specific to pediatric chronic anterior uveitis. Our next step is to validate in larger cohorts of children with anterior uveitis, and to compare the tear proteomic profile of children with JIA alone. Tear proteomic analysis is a promising area since tear collection is non-invasive and can be used to examine children with JIA who do not have uveitis. Discovery of biomarkers for screening and early detection of uveitis in children with JIA will help us identify those at highest risk for ocular disease.