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

Subhasish Pramanik,1,* Chinmay Saha,1,2,* Subhankar Chowdhury,1 Chiranjit Bose,1 Nitai P Bhattacharyya,1 Lakshmi Kanta Mondal3 1Department of Endocrinology & Metabolism, Institute of Post Graduate Medical Education & Research and SSKM Hospital, Kolkata, 700020, West Bengal, India; 2Genome Science, School of Interdisciplinary Studies, University of Kalyani, Nadia, 741235, West Bengal, India; 3Department of Ophthalmology, Regional Institute of Ophthalmology, Medical College Campus, Kolkata, 700 073, West Bengal, India*These authors contributed equally to this workCorrespondence: Subhankar ChowdhuryDepartment of Endocrinology & Metabolism, Institute of Post Graduate Medical Education & Research and SSKM Hospital, Kolkata, 700020, West Bengal, India, Email subhankar.chowdhury@gmail.comLakshmi Kanta MondalDepartment of Ophthalmology, Regional Institute of Ophthalmology, Medical College Campus, 88, College Street, Kolkata, 700 073, West Bengal, India, Email lakshmi.mondal62@gmail.comPurpose: 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