Abstract
Purpose:
Vitreo-macular traction plays an important role in the etiopathogenesis of disorders such as epiretinal membrane, macular hole and diabetic macular edema. Currently, there are clinical trials investigating the role of vitreolytics to release symptomatic vitreo-macular adhesion. In this study, we compared the protein profile of vitreous humor from patients undergoing vitreoretinal surgery with or without pre-existing posterior vitreous detachment (PVD) with quantitative proteomics.
Methods:
Vitreous humor, from 10 patients collected at the time of vitrectomy was divided into 2 groups based on the absence (control group, 5 samples) or presence (experimental group, 5 samples) of posterior vitreous detachment (PVD). From each sample, protein precipitate was alkylated, trypsin-digested, and labeled for the Isobaric tags for relative and absolute quantitation (iTRAQ). The samples were then pooled and fractionated by high pressure liquid chromatography (HPLC) and analyzed by tandem mass spectrometry (MS/MS). A database search was then performed using ProteinPilot v.4.2 software with a cutoff score set to 1.3 (confidence level of 95%).
Results:
Using iTRAQ labeling and the 2D LC-MS/MS method, 446 proteins were identified. Volcano plot revealed differential expression between control and experimental samples (more than 1.2 fold change) of eight proteins (Complement C3, Epididymis tissue sperm binding protein, Hemoglobin beta, Beta-crystallin A3, Beta-crystallin B1, filensin, HSP 90-beta 4 and a putative uncharacterized protein (F7V1R4) with a range of 2.86 to 11.45, p value <0.0001). The highest change was noted with heat shock protein (HSP 90-beta 4, with a fold change of 15.7), which acts as a molecular chaperone and causes protein degradation.
Conclusions:
Our study provides comprehensive proteome listing in vitreous humor samples in patients with posterior vitreous detachment. HSP 90-beta 4 was identified as one of the candidate proteins involved in induction of posterior detachment.
Keywords: 763 vitreous •
663 proteomics •
762 vitreoretinal surgery