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Abstract #21379 Published in IGR 10-2
Effects of modifiers of glycosaminoglycan biosynthesis on outflow facility in perfusion culture
Keller KE; Bradley JM; Kelley MJ; Acott TSInvestigative Ophthalmology and Visual Science 2008; 49: 2495-2505
PURPOSE: Glycosaminoglycans (GAGs) have been implicated in the regulation of outflow resistance of aqueous humor flow through the trabecular meshwork (TM). Their role was further investigated by assessment of the effects of chlorate, an inhibitor of sulfation, and beta-xyloside, which provides a competitive nucleation point for addition of disaccharide units, in anterior segment perfusion culture. METHODS: Outflow facility was measured in perfused porcine and human anterior organ cultures treated with 20 or 50 mM sodium chlorate, or 1 mM beta-xyloside. Perturbation of extracellular matrix (ECM) components was assessed in paraffin-embedded sections by immunofluorescence and confocal microscopy. Parallel experiments were conducted on cultured TM cells. RESULTS: Outflow facility increased in porcine eyes with chlorate (3-fold) and beta-xyloside (3.5-fold) treatments. In human eyes, outflow increased approximately 1.5-fold and took longer (> 48 hours) to occur. By confocal microscopy, immunostaining for chondroitin and heparan sulfates was observed on edges of human TM beams in nontreated eyes, with intense staining in the juxtacanalicular tissue (JCT) region. In treated eyes, staining of beam edges was severely reduced and was instead found in plaques. Chlorate treatment resulted in a striated pattern of GAG staining in the human JCT region. Fibronectin immunostaining was altered in beta-xyloside-treated eyes, whereas in cell culture, chlorate induced formation of thick fibronectin fibrils, to which tenascin C colocalized. CONCLUSIONS: Disrupting GAG chain biosynthesis increased outflow facility in perfusion culture and induced atypical ECM molecule interactions in cell culture. This study provides direct evidence of the critical role of GAG chains in regulating outflow resistance in human TM.
Dr. K.E. Keller, Casey Eye Institute, Oregon Health & Science University, Portland, OR, USA
Classification:
2.6.2.1 Trabecular meshwork (Part of: 2 Anatomical structures in glaucoma > 2.6 Aqueous humor dynamics > 2.6.2 Outflow)
3.8 Pharmacology (Part of: 3 Laboratory methods)
3.6 Cellular biology (Part of: 3 Laboratory methods)
