Paired Tear Fluid – Plasma Inflammatory Profiling Identifies Compartment-Specific Biomarkers for Diabetic Retinopathy and Diabetic Macular Edema

Objective: Diabetic retinopathy (DR) is a primary contributor to vision loss worldwide and growing with an increase in the elderly population. Preventing or slowing DR progression remains a critical unmet need. Recognizing the significance of systemic and ocular chronic inflammation in the progression of DR, this study aimed to explore inflammatory factor profiles in plasma and tear samples to identify potential biomarkers and therapeutic targets.
Methods: Using Olink’s proximity extension assay, 92 inflammation-related proteins were measured in paired plasma and tear samples of 42 participants in type 2 diabetes mellitus (T2DM), DR and Diabetic Macular Edema (DME), followed by bioinformatic analysis for differentially expressed proteins (DEPs).
Results: Different expression patterns of inflammatory proteins were observed between plasma and tear level. Plasma DEPs was mainly decreased during DR development, while tears DEPs mainly upregulated. DME had more differential cytokines than DR in both samples. By multi-comparison analyses, 23 inflammatory factors exhibited differential expression in the three compared groups (DR vs T2DM, DME vs T2DM and DME vs DR) in plasma level, and 30 differential inflammatory cytokines in tear samples. GO and KEGG analysis enriched pathways were primarily associated with extracellular region, cytokine activity, IL17 signaling pathway and JAK-STAT signaling pathway.
Conclusion: Tears exhibit more DEPs than plasma during the progression of DR and DME, and the two sample types show opposite inflammatory factor expression trends. The DEPs in tears, especially the newly discovered inflammatory factors TNFSF14, CXCL11, IL6, CCL19, DNER and CXCL9 may serve as potential biomarkers for the diagnosis and progression monitoring of DR and DME.