Tear Fluid Protein Changes in Dry Eye Syndrome Associated with Rheumatoid Arthritis: A Proteomic Approach

Sjögren syndrome (SS) secondary to rheumatoid arthritis (RA) affects lacrimal and salivary glands, and therefore dry eye syndrome (DES) is more prevalent in patients with RA. This study used a proteomic approach to identify potential biomarkers in tear of DES secondary to RA (DES-RA).

Tear specimens were collected with Schirmer strips from patients with DES with RA, patients with other types of dry eye (namely, primary Sjögrens and non-Sjögrens [NSS]), and age-matched controls. Tear proteins were subjected to 2D-differential gel electrophoresis (2D-DIGE), and the differentially expressed proteins were identified using nano ESI-LC-MS/MS analysis.

Among the differentially regulated proteins of DES-RA that were identified, lactotransferrin isoform 1 precursor was found to be d own-regulated in 100% cases and SHC transforming 1 isoform in 63% of the cases, while proteins such as ribonuclease p protein subunit 20, protocadherin, and heterogeneous nuclear ribonucleoprotein Q isoform 6 were down-regulated in over 80% of the cases. Proteins such as Ecto-ADP ribosyltransferase 5 precursor, Rho-related GTP-binding protein, and RhoJ precursor were up-regulated in 80% of the cases.

Functional annotation revealed that these proteins have roles in regulation, antimicrobial activity, immune, metabolic, and cellular processes. The study observed characteristic marker proteins differentially expressed in DES-RA that are previously unreported. Further validation is needed.