The following is a summary of “Proteomic study of aqueous humor in diabetic patients with cataracts by TMT combined with HPLC-MS/MS,” published in the October 2023 issue of Ophthalmology by Xu et al.
Researchers performed a retrospective study to identify proteomic differences in aqueous humor between diabetic and non-diabetic cataract patients.
The study divided patients into two groups, namely, a diabetic experimental group and a non-diabetic control group. Aqueous humor samples were collected during cataract surgery. These samples underwent protein treatment with a TMT reagent, separation through cation chromatography, and analysis using a C18 desalting column. Protein identification was done via HPLC-MS/MS. Differential proteins were determined based on a P-value of < 0.05 and a fold change of > 1.2. Subsequently, various analyses were conducted, including GO classification enrichment, KEGG pathway enrichment, protein interaction network analysis, and ingenuity pathway analysis. The expression of four differential proteins was confirmed by Western blot, and the expressions of GC and TTR were further assessed using a larger sample pool.
The result demonstrated that postprandial glucose levels significantly differed between the experimental group (9.40 ± 1.35 mmol/L) and the control group (6.56 ± 0.81 mmol/L) with a P-value of 1.16E-06. There were no statistically significant differences in baseline levels of the parameters. Of the 397 aqueous humor proteins identified, 137 exhibited significant differences, including 63 upregulated and 74 downregulated proteins. These differential proteins are involved in various biological processes and pathways, such as complement and coagulation cascades (P= 1.71E-09), and are associated with diabetic retinal degeneration and other diabetic complications. Proteins like HP, GC, and TTR played key roles in the protein interaction network. Western blot results confirmed that GC was downregulated, while TTR was upregulated in the aqueous humor under diabetic conditions.
The study found GC and TTR proteins in aqueous humor may be used as early diagnostic markers for diabetic eye complications.