Levels of adhesion molecules in peripheral blood correlat with stages of diabetic retinopathy and may serve as bio markers for microvascular complications

Abstract

Background: Proliferative diabetic retinopathy is a devastating complication of diabetes mellitus, developing within 15 years in 50% of patients with type 1 diabetes mellitus (DM) and in 10% of patients with type 2 DM. The correlation between levels of inflammatory markers in the peripheral blood and retinopathy staging has not been studied yet, and the purpose of this prospective study was to find a possible association between inflammation and staging of diabetic retinopathy.

Methods: A prospective (pilot) study that measured level of adhesion molecules in the peripheral blood of 10 healthy subjects and 30 patients with type 2 diabetes mellitus. Patients were grouped by the degree of retinopathy: 10 without retinopathy, 10 with non-proliferative retinopathy [NPDR] and 10 with proliferative retinopathy [PDR]. After signing the consent form, an ophthalmologic examination was performed, and 10 mL of blood was drawn. In order to assess adhesion molecules' level serum samples were collected, frozen, and stored at a temperature of -80 °C until analysis was performed as one batch.

Results: 10 healthy volunteers and 30 patients were enrolled. Healthy volunteers were younger (36.6 ± 7.9 years) compared to patients (no retinopathy 64.5 ± 10.8 years, NPDR 71.4 ± 8.9 years, and PDR 63.3 ± 11.6 years) (p = .0003 for all groups of patients in comparison with the healthy subjects). VCAM-1 levels were increased by retinopathy staging - starting from 81.86 ± 3.80 ng/ml (healthy), 105.55 ± 1.37 ng/ml (no retinopathy), 111.78 ± 4.14 ng/ml (NPDR), and 123.45 ± 3.99 ng/ml (PDR), with a significant difference between healthy and patients without retinopathy (p = .03), between no retinopathy and NPDR (p = .001), and between NPDR and PDR (p < .0001). E selectin was increased in correlation with severity of the retinopathy, with a significant difference between groups of patients (p = .03 between healthy subjects and T2DM patients without retinopathy, p = .001 between patients with T2DM no retinopathy and NPDR, p < .0001 between NPDR and PDR).

Conclusions: We found a significant increase in levels of adhesion molecules (VCAM-1) and selectins (E-selectin) in parallel with increased severity of diabetic retinopathy, with a significant difference of inflammatory markers between stages of retinopathy.

Keywords: Adhesion molecules; Diabetic retinopathy; Vascular complications.