Table 2.
Latest reports concerning miRNAs in biofluids of human patients with DR.
| miRNA | Sample Type | Expression in Research Group vs. Controls | Number of Cases | Method | Significant Findings | Year of Publication | References |
|---|---|---|---|---|---|---|---|
| miR-126 | serum | down in T2DM patients compared with control group | n = 186; 100 T2DM (14 without complications, 26 with macrovascular complications, 17 DN, 24 DNP, 19 DR), 86 IGT | qPCR | serum miR-126 expression might serve as a potential biomarker for DR | 2016 | [50] |
| serum | down | n = 184; 125 DM (44 NDR, 42 NPDR, 39 PDR) and 59 HC | qPCR | high values of AUC in ROC analysis determine miR-126 as a good diagnostic biomarker that differentiates PDR patients from HC | 2017 | [51] | |
| miR-200b | serum | down | n = 508; 255 DR, 253 HC | qPCR | miR-200b targets VEGFA gene | 2017 | [52] |
| miR-93 | plasma | up | n = 267; 140 T2DM (75 DR, 65 NDR) 127 HC | qPCR | levels of plasma miR-122 might serve as DR biomarkers | 2017 | [53] |
| miR-21 | plasma | up | n = 304; 65 NDR, 73 NPDR, 51 PDR, 115 HC | qPCR | elevated miR-21 expression can be used to identify occurrence and stage of DR | 2017 | [54] |
| miR-221 | serum | up (progressively upregulated in NDR, NPDR, and PDR) | n = 134; (33 HC, 37 NDR, 34 NPDR, 30 PDR) | qPCR | miR-221 might serve as a biomarker for progression and occurrence of DR | 2018 | [55] |
| let-7a- 5p miR-28-3p miR-novel-chr5_15976 |
serum | up | screening phase: 9 (3 T2DM NDR, 3 T2DM DR, 3 HC); training phase: 20 (10 T2DM NDR, 10 T2DM DR); validation phase: 79 (29 T2DM-DR, 50 T2DM NDR) |
RNASeq, qPCR | this miRNA signature may serve as a biomarker for DR; better than single miRNA | 2018 | [56] |
| miR-423 | serum | down in PDR | n = 69; (22 HC, 10 T2DM NDR, 22 NPDR, 15PDR) | qPCR | miR-423 may serve as a biomarker for DR; is correlated with VEGF, NO, and eNOS expression | 2019 | [57] |
| miR-122 | serum | up in T2DM NDR and T2DM with NPDRdown in T2DM PDR | n = 40; (10 of HC, 10 of T2DM NDR, 10 of T2DM with NPDR, 10 of T2DM with PDR | qPCR | levels of miR-122 in serum of T2DM patients might determine occurrence and progression of DR | 2019 | [58] |
| miR-29b, miR-200b | plasma | down | n = 206; 186 T2DM (91 NDR, 46 NPDR, 49PDR), 20 HC | qPCR | downregulation of miR-29b is associated with progression of DR | 2019 | [59] |
| miR-4448, miR-338-3p, miR-190a-5p, miR-485-5p, miR-9-5p | serum | down: miR-4448, miR-338-3p, miR-485-5p, and miR-9-5pup: miR-190a-5p | n = 21; 10 NPDR, 11 NDR | RNASeq | these miRNAs might serve as good potential biomarkers for DR with high AUC value (0.909) | 2019 | [60] |
| miR-3197, miR-2116-5p | serum | up | n = 90; 42 NPDR, 3 PDR, 45 NDR | microarray, qPCR | high diagnostic value of these 2 miRNAs can indicate patients with DR; NOTCH2 as a possible target gene of miR-2116-5p | 2020 | [61] |
| miR-320a | plasma | down | n = 170; 60 HC, 48 DM without DR, 62 DR | qPCR | DR can be identified by plasma miR-320a measurement; TSC1 and CDK6 are possible target genes for this miRNA | 2020 | [62] |
| let-7b, miR320b, miR-762, miR-4488 | aqueous humor, plasma, vitreous | miRNA let-7b—up in aqueous and vitreous, down—plasma miR-320b—up in aqueous, vitreous, and plasma miR-762 and miR-4488—up in vitreous; up in PDR, down in NPDR in aqueous; down in PDR and up in NPDR in plasma |
n = 27; 11 HC, 16 DM: 5 T1DM PDR, 7 T2DM PDR and 4T2DM NPDR | microarray, qPCR | this miRNA signature may contribute to the diagnostic tests or therapeutic approaches for the DR | 2020 | [63] |
AUC: area under curve; DR: diabetic retinopathy; DN: diabetic neuropathy; DNP: diabetic nephropathy; eNOS: endothelial nitric oxide synthase; HC: healthy controls; IGT: impaired glucose tolerance; NDR: no diabetic retinopathy; NO: nitric oxide; NPDR: non-proliferative diabetic retinopathy; PDR: proliferative diabetic retinopathy; qPCR: quantitative polymerase chain reaction; RNASeq: RNA sequencing; ROC: receiver operating characteristic curve; T1DM: type 1 diabetes mellitus; T2DM: type 2 diabetes mellitus; VEGF: vascular endothelial growth factor.