Using the Olink proteomics tear fluid biomarker approache to better understand keratoconus

Abstract

Purpose : To identify differentially expressed tear fluid proteins between keratoconus patients without signs of allergic conjunctivitis (KC), keratoconus patients with signs of allergic conjunctivitis (KC+AC) and allergic conjunctivitis patients (AC) using the Olink proteomics platform.

Methods : Tear fluid was collected using Schirmer’s strips. Proteins were extracted by elution and centrifugation. The total protein content was measured with the BCA assay. Proteomic profiling of 384 inflammatory proteins was assessed by a multiplex proximity extension assay (Olink Explore 384 Inflammation Panel). Proteins with NPX values below the LOD and those that did not QC control were omitted from data analysis. Statistical analysis was restricted to proteins that were detectable in ≥50% of the patient samples.

Results : Of 51 patients, 17 were keratoconus (KC), 17 allergic conjunctivitis (AC) and 17 combined (KC+AC). A total of 384 proteins were measured. The vast majority of proteins (n = 272) were commonly present in tear fluid samples of all three patient groups. Only a handful proteins were common between two groups and undetectable in another group, namely 5 proteins for KC+AC and AC and 6 proteins for KC+AC and KC. AC and KC did not share common proteins. Only one protein was identified as being unique to KC. AC and KC+AC did not contain any exclusive proteins. A total of 34 proteins were significant differentially expressed, of which 18 protein between AC and KC+AC, 9 proteins between KC and KC+AC and 18 proteins between KC and AC.

Conclusions : Our results reveal that the vast majority of tear fluid proteins overlap between keratoconus and allergic conjunctivitis. These similarities are suggestive for common underlying mechanisms and could contribute to the knowledge of the disease pathophysiology of keratoconus.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.