Comparative Tear Fluid Proteomics to Explore Treatment Responsiveness in Diabetic Macular Edema: A Pilot Study

Diabetic macular edema (DME) is a leading cause of vision
loss
in patients with diabetes, with variable responses to intravitreal
antivascular endothelial growth factor (VEGF) therapy. This study
aimed to identify tear fluid proteins linked to treatment responsiveness.
Tear fluid samples were collected from 13 patients with diabetes (21
eyes with DME), among which 9 samples were analyzed using tandem mass
tag-labeled liquid chromatography–mass spectrometry, and all
21 samples were validated with ELISA. Protein identification and quantification
were performed using MaxQuant. Gene set enrichment analysis identified
differentially expressed proteins, and an enzyme-linked immunosorbent
assay was used to validate specific protein targets. Among the 3121
quantified proteins, DME-related proteins were enriched in cellular
localization, oxidative stress response, and VEGFA-VEGFR2 signaling.
Responders’ tear fluid proteomes were linked to modulation
of the extracellular matrix and inflammation, whereas nonresponders
showed enrichment in inflammation and NOTCH/WNT pathways. Targeted
protein analysis demonstrated that the interplay between TIMP1, MMP9,
and insulin growth factor binding protein 3 (IGFBP3) correlated with
treatment response. These results suggest that tear fluid proteomic
analysis is a promising alternative to intraocular sampling for evaluating
DME responsiveness, offering insights consistent with aqueous and
vitreous proteomes while aligning with clinical prognosis and disease
pathophysiology.