Enzymatic breakdown of type II collagen in the human vitreous.
OBJECTIVE
To investigate whether enzymatic collagen breakdown is an active process in the human vitreous.


METHODS
Human donor eyes were used for immunohistochemistry to detect the possible presence of the matrix metalloproteinase (MMP)-induced type II collagen breakdown product col2-3/4C-short in the vitreous. Western blot and slot blot analyses were used to further identify vitreal type II collagen breakdown products in three age groups with average ages of 25, 45, and 65 years. Purified type II collagen was cleaved by MMPs that are known to occur naturally in the vitreous to elucidate what possible type II collagen breakdown products could thus be formed in the human vitreous.


RESULTS
By means of both immunohistochemistry and slot blot analysis, col2-3/4C-short was detected in the vitreous. Using Western blot analysis, a range of type II collagen breakdown products was found, mostly in younger eyes, but none of these products contained the neoepitope that characterizes the col2-3/4C-short molecule. Digestion of purified type II collagen by MMPs did not give the same breakdown products as found in the vitreous.


CONCLUSIONS
The presence of collagen degradation products in the human vitreous supports the hypothesis that enzymatic breakdown is most likely an active process in this extracellular matrix. Based on the size of the degradation products found by Western blot analysis, it is likely that in addition to MMPs, other proteolytic enzymes able to digest type II collagen are also active.
Department of Ophthalmology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
Mariëlle
M
van Deemter
Hendri H
HH
Pas
Roel
R
Kuijer
Roelofje J
RJ
van der Worp
Johanna M M
JM
Hooymans
Leonoor I
LI
Los
D000293:Adolescent; D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology; D000818:Animals; D015153:Blotting, Western; D002356:Cartilage / Q000378:metabolism; D024043:Collagen Type II / Q000378:metabolism*; D006801:Humans; D007124:Immunoenzyme Techniques; D020782:Matrix Metalloproteinases / Q000494:pharmacology / Q000502:physiology*; D008875:Middle Aged; D016612:Paraffin Embedding; D013552:Swine; D014019:Tissue Donors; D014822:Vitreous Body / Q000187:drug effects / Q000201:enzymology*; D055815:Young Adult
D024043:Collagen Type II; D020782:Matrix Metalloproteinases