Decreased Levels of miR-126 and miR-132 in Plasma and Vitreous Humor of Non-Proliferative Diabetic Retinopathy Among Subjects with Type-2 Diabetes Mellitus

Abstract

Purpose

Diabetic retinopathy (DR), the leading cause of blindness among working adults, is an urgent public health problem as diabetes mellitus (DM) is increasing at an alarming rate. Hyperglycemia-induced endothelial dysfunction is the principal contributing factor leading to the development of microangiopathy. Altered levels of microRNA (miR), the negative regulator of protein-coding genes, have been observed and considered to be markers for DR. Present study aimed to find out whether miR levels in plasma could be effective biomarkers to differentiate between type 2 diabetes mellitus (T2DM) with non-proliferative retinopathy (NPDR) from T2DM with no-DR (DNR).

Methods

We recruited 50 T2DM subjects comprising 31 NPDR and 19 DNR individuals. Surrogate markers of systemic oxidative stress and vascular endothelial growth factor (VEGF) were measured in plasma. Levels of miR-126 and miR-132 were determined in plasma and vitreous fluid using real-time PCR.

Results

We observed that levels of miR-126 and miR-132 were decreased in NPDR subjects in comparison to DNR. Plasma levels of miRs were inversely correlated with secreted levels of VEGF and oxidative stress marker. The levels of these miRs showed discriminating ability between NPDR and DNR.

Conclusion

Circulating miRs 126 and 132 in plasma or vitreous may serve as biomarkers for early diabetic retinopathy risk prediction, provided validated in a larger cohort and other forms of retinal vasculopathy or retinopathy in the future.

Keywords:

• diabetic retinopathy
• microRNA-126
• microRNA-132
• oxidative stress
• malondialdehyde
• vascular endothelial growth factor

Ethics and Consent

The study was approved by the Institutional Ethics Committee (Medical College, Kolkata, Ref. No: MC/ KOL/IEC/NON-SPON/181/12-2018), and informed consents were collected from all patients according to the declaration of Helsinki.

Acknowledgments

Prof Ashim Kumar Ghosh, Director Regional Institute of Ophthalmology, for his encouragement and support towards the fulfillment of this work. We also want to acknowledge “Multidisciplinary Research Unit” (MRU) of IPGME&R and SSKM Hospital for providing us trichloroacetic acid (TCA) reagent (Sigma-Aldrich, CAS Number 76-03-9) for MDA measurement.

Disclosure

The authors declare no conflicts of interest for this work.

Additional information

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.