Abstract
Purpose: :
Although the levels of several proteins and cytokines in aqueous humor (AH) have been reported to change in patients with neovascular age-related macular degeneration (AMD), the whole proteome changes in AH of these patients remain unknown. Therefore, profiling and characterization of the whole proteome of AH from patients with neovascular AMD in vivo were initiated to elucidate the novel molecular aspect of AMD and find new biomarkers associated with it.
Methods: :
Samples of AH were collected from four patients with treatment-naïve neovascular AMD and four age and sex-matched patients undergoing cataract surgery (controls). Samples from patients were obtained before performing the first intravitreal injection of ranibizumab 0.5 mg and 1 month after the first injection of ranibizumab. Proteins from AH samples were quantified, separated with SDS-PAGE, and underwent enzymatic in-gel digestion. Nano-LC-ESI-MS/MS analysis was done to identify and quantify the AH proteomes. The study followed the tenets of the Declaration of Helsinki.
Results: :
A total average of 601 and 473 proteins were identified in the AH of patients and controls. Levels of cytokeratin18 and 19 decreased in patients and increased markedly (1.3-8 fold) after treatment. Along with cytokeratin, desmoplakin, another marker of epithelial cells, increased remarkably after treatment. It was also found that autophagy-related protein 7, lysozyme, and cathepsin D increased 1.6-9 fold in patients and decreased significantly after treatment. Other proteins which had increased more than twofold in patients and then decreased after treatment included those related to stress response, antioxidant activity and proteasome. Among these, proteins such as complement factor B and H, gelsolin, collagen alpha, annexin A1, glutathione transferase and clusterin may be possible secretory proteins from the retinal pigment epithelium and/or retina.
Conclusions: :
The present study demonstrates that the proteomic composition of AH of patients with neovascular AMD differed significantly from that of the controls. This experiment provides new potential biomarkers and therapeutic target proteins in AMD, including proteins related to cytokeratins and autophagy.
Keywords: age-related macular degeneration • proteomics • retinal pigment epithelium