Characterisation of the vitreous proteome in proliferative diabetic retinopathy

Abstract

BackgroundDiabetes can lead to serious microvascular complications such as proliferative diabetic retinopathy (PDR), which results in severe vision loss. The diabetes-induced alterations in the vitreous protein composition in diabetic patients with PDR may be responsible for the presence of PDR. The vitreous humour can be utilised in a variety of studies aimed toward the discovery of new targets for the treatment or prevention of PDR and the identification of novel disease mechanisms. The aim of this study was to compare the protein profile of vitreous humour from diabetic patients with PDR with that of vitreous humour from normal human eyes donated for corneal transplant.ResultsVitreous humour from type 2 diabetic patients with PDR (n = 10) and from normal human eyes donated for corneal transplant (n = 10) were studied. The comparative proteomic analysis was performed using two-dimensional fluorescence difference gel electrophoresis (2-D DIGE). Differentially produced proteins (abundance ratio > 2 or < -2, p < 0.01) were identified by matrix-assisted laser desorption ionisation time-of-flight mass spectrometry (MALDI-TOF MS) and MALDI-TOF tandem mass spectrometry. A total of 1242 protein spots were detected on the 2-D master gel of the samples, and 57 spots that exhibited statistically significant variations were successfully identified. The spots corresponded to peptide fragments of 29 proteins, including 8 proteins that increased and 21 proteins that decreased in PDR. Excluding the serum proteins from minor vitreous haemorrhage, 19 proteins were found to be differentially produced in PDR patients compared with normal subjects; 6 of these proteins have never been reported to be differentially expressed in PDR vitreous: N(G),N(G)-dimethylarginine dimethylaminohydrolase 1 (DDAH 1), tubulin alpha-1B chain, gamma-enolase, cytosolic acyl coenzyme A thioester hydrolase, malate dehydrogenase and phosphatidylethanolamine-binding protein 1 (PEBP 1). The differential production of pigment epithelium-derived factor (PEDF) and clusterin was confirmed by Western blot analysis.ConclusionsThese data provide an in-depth analysis of the human vitreous proteome and reveal protein alterations that are possibly involved in the pathogenesis of PDR. Further investigation of these special proteins may provide potential new targets for the treatment or the prevention of PDR.

Diabetes-related alterations in the enteric nervous system and its microenvironment

“…The EGCs network has trophic and protective functions toward enteric neurons and is fully implicated in the integration and the modulation of neuronal activities [33][34][35] . In addition, EGCs within the ENS have a significant role in forming a diffusion barrier around the capillaries surrounding ganglia similar to that of bloodbrain barrier [3,15,[36][37][38] .…”

Endothelial Protein C–Targeting Liposomes Show Enhanced Uptake and Improved Therapeutic Efficacy in Human Retinal Endothelial Cells

“…3,4 Several studies have indicated that there is a significant increase in the levels of proangiogenic and proinflammatory factors and cytokines (e.g., vascular endothelial growth factor, IL-8, TNF-a, IL-6, and IL-1b) in the vitreous of a patient with diabetic retinopathy. [40][41][42][43] These findings have led to the emergence of several novel treatment modalities based on the administration of antivascular endothelial growth factor agents and corticosteroids to the diseased retina. 44,45 Corticosteroids are an attractive option due to their broad range of actions including anti-inflammatory and antiangiogenic effects.…”

Biocompatibility of Poly(ester amide) (PEA) Microfibrils in Ocular Tissues

“…Although chymotrypsin is a digestive system enzyme, it degrades proteins hydrolytically in a manner similar to enzymes present in ocular tissues including the vitreous humor [17,35]. Proteomic analyses has confirmed the presence of a number of enzymes in the vitreous humor such as carbonic anhydrase, the glutathione peroxidase or the prostaglandin D2 synthase [36], and 51 proteases, some of which show increases in diseases like the diabetic retinopathy [37][38][39][40]. Contrary to the degradation of PLGA [1], which takes place in the bulk via cleavage of its backbone ester linkages into oligomers and finally monomers [13], degradation of PEA fibrils appears to take place by surface erosion, suggesting that barrier properties of PEA matrix will be preserved during the entire life-time of the implant [22], a characteristic that would allow PEAs to be used for the fabrication of long-term, controlled release devices.…”