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Vitreoretinal Adhesion (vitreoretinal + adhesion)

Distribution by Scientific Domains

Medical Sciences	100%

Selected Abstracts

An interaction between opticin and heparan sulfate may provide the molecular basis for vitreoretinal adhesion

INTERNATIONAL JOURNAL OF EXPERIMENTAL PATHOLOGY, Issue 4 2004
V. John Hindson
Introduction Opticin is a member of the extracellular matrix small leucine-rich repeat (SLRP) proteoglycan/protein family, which was originally identified in the eye associated with the collagen fibrils of the vitreous humour. A putative heparin/heparan sulfate (HS) binding motif (RKERKRR) was identified at the N-terminus of human opticin, but this is absent in the bovine form. Furthermore, the strength of attachment between the vitreous and the retina was observed to be species-dependent and related to the presence or absence of this motif. We hypothesized that opticin cross-links the collagen fibrils of the vitreous to HS proteoglycans in the inner limiting lamina (a basement membrane on the inner surface of the retina), contributing towards vitreoretinal adhesion. Materials and methods Recombinant human and bovine opticin were expressed in 293-EBNA cells and purified to apparent homogeneity. Solid phase assays and surface plasmon resonance studies were used to characterize interactions between immobilized heparin/HS and opticin. Results Solid phase and BIAcore data revealed that human opticin binds heparin/HS and binds to heparin with a dissociation constant of approximately 20 nm. By contrast bovine opticin, which lacks the basic cluster, bound severalfold less tightly. Competition studies with heparin oligosaccharides indicated that the heparin/HS binding site is greater than 6 monosaccharides in length. Heparin, HS, chondroitin sulfate A (CS-A), dermatan sulfate and hyaluronan all competed with heparin for binding to human opticin but CS-C did not. Discussion Work to date suggests that the N-terminal sequence RKERKRR contributes significantly to the binding of opticin to heparin/HS. Vitreoretinal adhesion plays a key role in a number of eye diseases and inhibitors of the opticin,HS interaction could be of therapeutic value. [source]

Insights into the molecular basis of rhegmatogenous retinal detachment

ACTA OPHTHALMOLOGICA, Issue 2009
PN BISHOP
Purpose Factors that determine the likelihood of developing posterior vitreous detachment and subsequent rhegmatogenous retinal detachment (RRD) include (i) the degree of vitreous liquefaction (ii) the strength of post-basal vitreoretinal adhesion and (iii) the topology of the posterior border of the vitreous base. The purpose of these studies was to investigate each of these using a combination of ultrastructural and molecular techniques. Methods Ultrastructural studies of the human vitreous and vitreoretinal interface were performed in combination with various antibodies and cationic dyes. Biochemical studies were performed on extracted vitreous components. Results The resultant data suggest that: (i) vitreous liquefaction is caused by the aggregation of vitreous collagen fibrils and this is due to a loss of type IX collagen proteoglycan from the fibril surfaces; (ii) interactions between heparan sulphate proteoglycans in the inner limiting lamina and components on the surface of cortical vitreous collagen fibrils contribute to postbasal vitreoretinal adhesion; (iii) the posterior border of the vitreous base migrates posteriorly with aging due to the synthesis of new vitreous collagen by the peripheral retina. Conclusion The molecular basis of RRD is starting to be unravelled. Furthering our understanding of the underlying molecular processes may lead to the development of novel therapeutic strategies to treat RRD and other vitreoretinal disorders. [source]