Endocrine Abstracts

Background

Diabetic retinopathy is the leading cause of blindness in working-age adults in developed world. Derangements of ubiquitine-proteasome system and telomere length have been associated with microangiopathy in diabetes. Until now, limited data are available on above markers in diabetic retinopathy in type 1 diabetes (T1D).

Aim

The aim of this work was to compare serum proteasome concentration and telomere length in patients with different stages of diabetic retinopathy and T1D in Latvia and Lithuania.

Methods

186 Latvian and 120 Lithuanian patients with type 1 diabetes were enrolled. Patients were stratified according to severity of diabetic retinopathy. Group of severe retinopathy included patients with proliferative retinopathy and status post laser-photocoagulation. “No retinopathy” group included patients with nonproliferative/no retinopathy. Proteasome concentration was measured by ELISA. Telomeres were evaluated by real-time qPCR with a relative telomere length method using a reference gene and expressed as (∆CT). Statistical analysis was performed in programme R. Wilcoxon rank sum test followed by Ancova on ranks was used to compare the locations of biomarkers distributions between the groups of retinopathy and to adjust for covariates (diabetes duration, waist/hip ratio, serum triglycerides, estimated glomerular filtration rate (eGFR), country).

Results

Subjects in the group of severe retinopathy (n = 119) compared to “no retinopathy” (n = 187) were statistically significantly older (44 (35–53.5) vs. 31 (24.5–44) years), had longer duration of diabetes (28 (22–36) vs. 16 (12–21.5) years), higher serum creatinine concentration and lower estimated glomerular filtration rate, higher serum triglyceride and waist–hip ratio, as well as higher prevalence of other complications of diabetes. We observed lower serum proteasome concentration in the group of severe retinopathy (130 (90–210) ng/ml, vs. “no retinopathy” 150 (100–240) ng/ml), difference was significant after adjustment for covariates, P = 0.024. Median telomere length was higher in the group of severe retinopathy (∆CT 0.21 (0.12–0.28 vs “no retinopathy” 0.18 (0.1–0.28), difference was significant after adjustment for covariates, P = 0.036.

Conclusion

In this study, we demonstrated differences in proteasome concentration and telomere length between patients with different stages of diabetic retinopathy.

Acknowledgements

Mutual funds Taiwan – Latvia – Lithuania project “Novel biomarkers of diabetic retinopathy: epigenetic modifications of genes of ubiquitine-proteasome system, telomere length and proteasome concentration”, grant “Research of biomarkers and natural substances for acute and chronic diseases’ diagnostics and personalized treatment” by the Faculty of Medicine, University of Latvia and Genome Database of Latvian population. We thank Gunita Varblane and Juris Stefanovičs for assessment of serum proteasome concentration and telomere length.