Monocyte Chemoattractant Protein-1 Level Measured in Dried Blood Spots as a Biomarker for Diabetic Retinopathy

To identify inflammatory proteins that differ between diabetic patients with and without retinopathy and to evaluate the feasibility of dried blood spots (DBSs) to measure monocyte chemoattractant protein-1 (MCP-1).

In part I, we recruited 74 patients with diabetic retinopathy (DR) and 82 diabetic patients without retinopathy (DM no DR). We compared plasma concentrations of inflammatory proteins between groups. In part II and part III, we included 39 patients consisting of 13 DR patients, 13 DM no DR patients, and 13 patients without diabetes. We compared the level of the significant protein identified from part I between disease groups (part III) and between vial blood and DBSs (part II). We also conducted receiver operating characteristic curve analysis.

From part I, we identified MCP-1 as significantly higher in male DR patients than in male DM no DR patients with 5 to 10 years of diabetes. In part II and part III, multivariable regression controlling for clinical characteristics showed elevated MCP-1 levels in the DR group (coefficient 22.36 pg/mL, P = 0.008) compared to control patients without diabetes. The direct comparison between DR patients and DM no DR patients showed a nonsignificant trend of higher MCP-1 in DR patients. The area under the curve for DBS-derived MCP-1 was 0.754 (95% confidence interval, 0.594-0.915), with an optimal DR threshold of 20.47 pg/mL, yielding a sensitivity of 100% and a specificity of 53.8%.

Elevated MCP-1 in DR patients suggests its potential use as a biomarker for DR. We identified thresholds of MCP-1 in DBS for DR screening.

Our study supports the potential feasibility of point-of-care testing of MCP-1 for DR risk stratification.