Effect of heparin II domain of fibronectin on aqueous outflow in cultured anterior segments of human eyes.
OBJECTIVE
To determine whether an integrin/syndecan-binding domain of fibronectin, called the heparin II (Hep II) domain, affects outflow facility in the human eye.


METHODS
Anterior segments of human eyes were placed in perfusion organ culture. One eye of each pair received the Hep II domain, and the fellow eye received DMEM or a heat-denatured Hep II domain. The Hep II domain was produced as a recombinant glutathione S-transferase (GST)-fusion protein. Microscopic changes were assessed.


RESULTS
Outflow facility in anterior segments treated with Hep II domain increased by 93% compared with that in anterior segments treated with DMEM. In contrast, facility in anterior segments treated with the heat-denatured Hep II domain showed very little change. Outflow facility remained high during Hep II domain perfusion and returned to baseline after removal of the protein. Electron microscopy revealed disruptions in the endothelial lining of Schlemm's canal in anterior segments fixed during maximum effect and in anterior segments after facility had returned to baseline. Scattered disruptions of canal cells were noted in control anterior segments. Trabecular cells in other regions looked normal. Major changes in the extracellular matrix of the juxtacanalicular tissue were not observed. Repeated doses of the Hep II domain administered after facility returned to baseline increased facility in two of three anterior segments.


CONCLUSIONS
The Hep II domain of fibronectin increases outflow facility in the human anterior segment. This suggests that fibronectin-mediated interactions may have a role in modulating aqueous hydrodynamics. Such interactions may represent avenues of novel therapeutic interventions for glaucoma.
Department of Pathology and Laboratory Medicine, University of Wisconsin, Madison, Wisconsin 53706, USA.
Amy J
AJ
Santas
Cindy
C
Bahler
Jennifer A
JA
Peterson
Mark S
MS
Filla
Paul L
PL
Kaufman
Ernst R
ER
Tamm
Douglas H
DH
Johnson
Donna M Pesciotta
DM
Peters
D000368:Aged; D000369:Aged, 80 and over; D000869:Anterior Eye Segment / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D001082:Aqueous Humor / Q000378:metabolism*; D005353:Fibronectins / Q000378:metabolism* / Q000494:pharmacology*; D006493:Heparin / Q000378:metabolism* / Q000494:pharmacology*; D006801:Humans; D007124:Immunoenzyme Techniques; D039041:Integrin alpha4beta1 / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000378:metabolism; D008875:Middle Aged; D009924:Organ Culture Techniques; D010446:Peptide Fragments / Q000494:pharmacology; D011509:Proteoglycans / Q000378:metabolism; D011993:Recombinant Fusion Proteins; D053667:Syndecans
D005353:Fibronectins; D039041:Integrin alpha4beta1; D008562:Membrane Glycoproteins; D010446:Peptide Fragments; D011509:Proteoglycans; D011993:Recombinant Fusion Proteins; D053667:Syndecans; D006493:Heparin