Table 5.
Summary of selected studies utilizing proteomics technology on various samples to determine novel proteins associated with presence of varying stages of diabetic retinopathy.
| Sample analyzed | Reference/study design | Sample size | Key findings | Method of analysis |
|---|---|---|---|---|
| Serum | Kim et al., 2013/cross sectional | N = 60 (15 NDR, 15 mild NPDR, 15 moderate NPDR, and 15 severe NPDR) | Twenty-eight candidate proteins were identified that underwent changes in expression with progression of retinopathy. Combinations of four of these proteins were able to distinguish between mild, moderate, and severe NPDR generating AUC values (>0.7) (see main text for details) | Multiple reaction monitoring (MRM) using triple quadrupole LC-MS/MS (4000 QTrap coupled with nano Tempo MDLC, Applied Biosystems) |
| Serum | Liu et al., 2011/cross sectional | N = 32 (8 NDR, 8 NPDR, 8 PDR, 8 healthy controls) | Four low abundance proteins identified (β2-GPI, AHSG, α1-AGP, apo A1); β2-GPI expression increased with progressive severity of DR (NDR vs. NPDR ratio 1.58; NDR vs. PDR ration 1.84) PDR vs. NPDR no significant rise (ratio = 1.17) | 2D-DIGE |
| Tear fluid | Csosz et al., 2012/cross sectional | N = 145 (119 diabetics with NDR, NPDR and PDR, 26 healthy volunteers | Six proteins were identified as possible markers of DR in tear fluid (lipocalin 1, lactotransferrin, lacritin, lysozyme C, lipophilin A, and immunoglobulin lambda chain) | Nano HPLC couples with ESI-MS/MS mass spectrometry |
| Tear fluid | Kim et al., 2012/cross sectional | N = 41 (NDR 10, NPDR 17, healthy controls 14) | Twenty proteins were differentially expressed between the study groups, three of which were confirmed by Western Blot (LCN-1, HSP 27, B2M) | ESI-Q-TOF MS/MS |
NDR, diabetic with no retinopathy; NPDR, no proliferative diabetic retinopathy; PDR, proliferative diabetic retinopathy; 2D-DIGE, two dimensional fluorescence difference gel electrophoresis; β2-GPI, beta 2- glycoprotein I, AHSG, alpha2-HS-glycoprotein; α1-AGP, alpha1acid glycoprotein, apo A1, apolipoprotein A1; LCN1, lipocalin 1; HSP 27, heat shock protein 27; B2M, beta-2 microglubulin.