Abstract
Purpose: :
To characterize and compare the protein composition of the developing and adult human vitreous.
Methods: :
Human vitreous samples were obtained from the 2nd trimester of development (n=14, 14-20w gestation), adults with macular hole or epiretinal membrane (n=4, 75-83y), and subjects with proliferative diabetic retinopathy (PDR, n=4, 40-57y). Vitreous proteins were analyzed by 1D SDS-PAGE and nano-LC tandem mass spectrometry. Assignments were performed using X!Tandem and IPI_human database v3.45. Results from the low mw protein fraction (below an albumin cutoff) were compared among samples sets.
Results: :
We identified 1213 and 314 proteins in the fetal and adult vitreous, respectively, including 1002 unique to fetal and 78 unique to the adult vitreous. A large fraction of the fetal vitreous proteome was annotated as intracellular proteins, consistent with the remodeling of hyaloid structures and retina during this period. Putative secreted proteins that were increased in both fetal and PDR vitreous compared with control adult vitreous included PEDF, RBP4, AMBP, hemoglobin, and a number of Ig chains. Proteins that were identified primarily in PDR vitreous included carbonic anhydrase 1, CHI3L1, and complement 4B. Proteins identified in strikingly higher abundance in fetal vitreous compared with adult vitreous included low MW kininogen-1, cystatin B, IGF BP -2 and -4, thrombospondins -1 and -4, thioredoxin, mu-crystallin, alpha-2-antiplasmin, nidogen-2, and growth/differentiation factor 8. Extracellular matrix proteins detected in fetal vitreous in this low MW range included COL5A1, 6A3, 11A1, 15A1, 1A1, 2A1, 4A2, and 18A1.
Conclusions: :
This study begins to characterize the composition of human vitreous during the 2nd trimester of fetal development. Comparison of the fetal and adult vitreous proteomes reveals individual protein and protein family differences that exist in the posterior segment during development as compared to the adult vitreous, as well as protein differences that are recapitulated in PDR vitreous. Further characterization of the fetal vitreous proteome may provide new insights into the mechanisms of ocular development and suggest new factors that may contribute to proliferative retinopathies.
Keywords: vitreous • development • diabetic retinopathy