Comprehensive Proteomic Profiling of Aqueous Humor Proteins in Proliferative Diabetic Retinopathy

Abstract

Purpose Proliferative diabetic retinopathy (PDR) is a serious ocular disease that can lead to retinal microvascular complications in patients with diabetes mellitus. To date, no studies have explored PDR development by analyzing the aqueous humor (AH). Therefore we carried out tandem mass tag (TMT) proteomic quantification to compare AH protein profiles between PDR and non-PDR subjects. Methods We enrolled six PDR and six control (senile cataract) subjects. AH samples were collected during surgery and stored at –80°C. Proteins were extracted, trypsin-digested, and labeled with TMTs for mass spectrometric analysis. Results We found 191 proteins to be changed with |log 2 (fold change)| ≥1 ( P < 0.05 and identification with at least two peptides per protein). Of them, 111 were downregulated, whereas 80 were upregulated in the PDR group. Proteomic bioinformatic analysis indicated that PDR development was related to complement and coagulation cascades, platelet activation, extracellular matrix–receptor interaction, focal adhesion, protein digestion and absorption, human papillomavirus infection, PI3K-Akt signaling pathway, cholesterol metabolism, peroxisome proliferator-activated receptor signaling pathways, fat digestion and absorption, and vitamin digestion and absorption pathways. Conclusions Comprehensive proteomic profiling of the AH revealed 191 differentially expressed proteins between the two groups. Most of these proteins belong to secretory pathways, and therefore can be used as biomarkers in clinical testing and basic research. Translational Relevance Pathway analysis and a review of the literature enabled us to draw a novel biological map that will support further studies on the underlying mechanisms and therapeutic control of PDR development.

The neutrophil percentage‐to‐albumin ratio is related to the occurrence of diabetic retinopathy

“…Patients with DR and animal models have been shown to exhibit a variety of inflammation-related characteristics, including tissue edema, enhanced vascular permeability, elevated blood flow, up-modulation of cytokines, activation of complement and microglial, infiltration of neutrophils and macrophages, and leukostasis. [34][35][36] Notably, the elevation in these inflammatory factors that are produced by microglia, endothelial cells, macroglia, and later even neurons indicates dramatic increases in the activities of these inflammatory markers in the early stage of DR and the progression of inflammation across all the cell types of the retina. 37,38 Some of the cytokines identified, such as interleukin (IL)-1, IL-3, and monocyte chemoattractant protein-1 (MCP-1) are reported to be involved in angiogenesis, as demonstrated in experimental ischemic mouse models demonstrating that inflammatory responses lead to and predate the progression of neovascularization in proliferative DR. 39,40 Moreover, it has been proven that blocking or deleting pro-inflammatory markers can inhibit the progression of diabetes-elicited vascular and neuronal pathology in animal models of the DR. 41,42 According to the aforementioned results, we hypothesized that NPAR, the blending of albumin and neutrophils, has a high prognostic significance in the progression of DR. NPAR is simplistic, inexpensive, and rapid, which makes it a potential indicator that may be used even in undeveloped medical areas.…”

“…Patients with DR and animal models have been shown to exhibit a variety of inflammation‐related characteristics, including tissue edema, enhanced vascular permeability, elevated blood flow, up‐modulation of cytokines, activation of complement and microglial, infiltration of neutrophils and macrophages, and leukostasis 34–36 . Notably, the elevation in these inflammatory factors that are produced by microglia, endothelial cells, macroglia, and later even neurons indicates dramatic increases in the activities of these inflammatory markers in the early stage of DR and the progression of inflammation across all the cell types of the retina 37,38 .…”

Integrated Analysis of Metabolomics and Lipidomics in Plasma of T2DM Patients with Diabetic Retinopathy

“…The altered plasma levels of amino acids and derivatives in infants with ROP were also identified by untargeted metabolomics and validated by targeted metabolomics [18,40]. Xiao et al [41] conducted proteomic profiling of aqueous humor in PDR patients and showed that "protein digestion and absorption" is one of the pathways most enriched by the dysregulated proteins. Interestingly, enriched KEGG pathways were found in the present study and in the previous studies on OIR and ROP, indicating the importance of protein digestion and absorption in DR pathogenesis.…”

Investigating the Mechanisms of Pollen Typhae in the Treatment of Diabetic Retinopathy Based on Network Pharmacology and Molecular Docking

“…According to the study results, those genes enriched in focal adhesion signaling pathway were considerably upregulated [ 53 – 55 ]. Moreover, proteomic bioinformatic analysis in DR indicated that DR development was closely related to focal adhesion and PI3K-Akt signaling pathway [ 56 ]. For the VEGF signaling pathway, one study's results suggested that the inhibition of the VEGF signaling pathway could protect diabetic retina, and this protective effect might be related to anti-inflammatory and antioxidative activities [ 57 ].…”