Chondroitin Sulfate Proteoglycans Are Structural Renewable Constituents of the Rabbit Vitreous Body

Góes, Rejane Maira; Nader, Helena B.; Porcionatto, Marimélia; Haddad, Antônio; Laicine, Eduardo Miguel

doi:10.1080/02713680590934148

Cited by 21 publications

(11 citation statements)

References 30 publications

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“…4 Transmission electron microscopy and high-magnification light microscopy performed on fixed human specimens have suggested that collagen fibril fragmentation may accompany age-related vitreous liquefaction. 5 High-resolution electron microscopy also has suggested important roles for chondroitin sulfate proteoglycans 6 and hyaluronan 3 in maintaining adequate spacing between the collagen fiber network, results supported by the finding that loss of type IX collagen proteoglycan sidechains occurs during age-related vitreous liquefaction. 7 Inherent in the preceding approaches is the need for sample fixation and magnification at micrometer, or even nanometer resolution to allow for the visualization of macromolecular structure.…”

mentioning

confidence: 91%

Quantitative Imaging of Enzymatic Vitreolysis-Induced Fiber Remodeling

Filas

Shah

Zhang

et al. 2014

Investigative Ophthalmology & Visual Science

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Proteoglycan loss due to enzymatic vitreolysis differentially increases fiber alignment at locations where tractions are most common. We hypothesize that a similar mechanism leads to retinal complications during age-related vitreous degeneration. Structural changes to the entire vitreous body (as opposed to the vitreoretinal interface alone) should be evaluated during preclinical testing of pharmacological vitreolysis candidates.

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mentioning

confidence: 91%

Quantitative Imaging of Enzymatic Vitreolysis-Induced Fiber Remodeling

Filas

Shah

Zhang

et al. 2014

Investigative Ophthalmology & Visual Science

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“…47 These conclusions are supported by a study showing that digestion of the vitreous with chondroitin ABC lyase, an enzyme that degrades the CS chains of type IX collagen, resulted in the aggregation of collagen fibrils. 56 HA provides a swelling pressure to the collagen network and hence the vitreous gel. Complete (enzymatic) removal of the HA resulted in gel shrinkage, but not complete collapse; so HA is not a prerequisite for the gel structure.…”

Section: Vitreous Liquefactionmentioning

confidence: 99%

Adult vitreous structure and postnatal changes

Goff

Bishop

2008

Eye

275

206

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This review will focus on the molecular organisation of the adult vitreous and how it undergoes ageing changes throughout life that result in vitreous liquefaction and a predisposition towards posterior vitreous detachment and retinal break formation. At birth, the vitreous humour is in a gel state due to the presence of a network of fine collagen fibrils. With ageing, these collagen fibrils progressively aggregate due to a loss of type IX collagen from their surfaces. The aggregation of collagen fibrils may cause vitreous liquefaction which, when combined with an age-related weakening of postbasal vitreoretinal adhesion, predisposes to posterior vitreous detachment. Throughout postnatal life, the posterior border of the vitreous base migrates posteriorly from the ora serrata into the peripheral retina. This is due to new collagen synthesis by the peripheral retina. This new collagen intertwines with pre-existing cortical vitreous collagen to create new adhesions and thereby extends the vitreous base posteriorly. If irregularities in the posterior border of the vitreous base arise from this process, there is a predisposition towards retinal break formation during posterior vitreous detachment and subsequent rhegmatogenous retinal detachment.

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“…29 HSPG is also present in the vitreous, and labeling studies demonstrate that this compound forms de novo in the vitreous cavity. 30 Although pro-teoglycans are thought to have a structural role in the vitreous, HSPG has been implicated in regulating inflammatory pathways 31 and can bind both FGF and VEGF. 32 Through its ability to bind and complex with VEGF, HSPG 33,34 has profound effects on the bioactivity of VEGF, affecting its diffusion, halflife, and interaction with its tyrosine kinase receptors.…”

Section: Discussionmentioning

confidence: 99%

Vitreous VEGF Clearance Is Increased after Vitrectomy

Lee

Ghosn

et al. 2010

Invest. Ophthalmol. Vis. Sci.

112

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Purpose. Pars plana vitrectomy (PPV) has been reported to reduce macular thickness and improve visual acuity in patients with diabetic macular edema (ME). The hypothesis for the study was that after PPV, clearance is accelerated and VEGF concentrations are reduced. To test this hypothesis, hVEGF(165) injections were performed in rabbit eyes, with and without PPV, and vitreous VEGF levels were measured as a function of time. Methods. The PPV group rabbits had a bilateral 25-gauge PPV, and in the no-PPV group, rabbits had intact vitreous. Intravitreal injections of hVEGF(165) were performed, and the animals were euthanatized at time points up to 7 days. The vitreous was isolated and an enzyme-linked immunosorbent assay was used to measure the VEGF levels. Pharmacokinetic parameters were determined in a noncompartmental analysis approach. Results. Mean vitreous VEGF levels decreased more rapidly in eyes subjected to PPV than in no-PPV eyes. The vitreous VEGF half-life (t([)(1/2)(])) in PPV eyes was 10 times shorter than that in normal eyes. In addition, mean clearance and mean area under the curve (AUC) increased and decreased, respectively, in eyes that underwent PPV. Conclusions. VEGF clearance is increased after PPV. Reducing VEGF concentrations in the vitreous post-PPV may partially explain the improvement in macular thickness in some patients with ME. Unexpectedly, the half-life of VEGF in the vitreous, even in no-PPV eyes, was <3 hours, whereas compounds of similar molecular weight typically have longer vitreous half-lives. The back of the eye may be uniquely adapted with rapid-clearance mechanisms to regulate vitreous VEGF levels. Further study is suggested.

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Chondroitin Sulfate Proteoglycans Are Structural Renewable Constituents of the Rabbit Vitreous Body

Abstract: At least one of the chondroitin sulfate PGs is involved in the interactions that occur in the vitreous structure, mainly by providing adequate spacing between the collagen fibrils, a condition that is probably required for the transparency of the vitreous.

Cited by 21 publications

References 30 publications

Quantitative Imaging of Enzymatic Vitreolysis-Induced Fiber Remodeling

Quantitative Imaging of Enzymatic Vitreolysis-Induced Fiber Remodeling

Adult vitreous structure and postnatal changes

Vitreous VEGF Clearance Is Increased after Vitrectomy

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