scholarly journals A cornealis sebgyógyulás és az extracelluláris mátrix

2016 ◽  
Vol 157 (25) ◽  
pp. 995-999
Author(s):  
Gréta Varkoly ◽  
János Bencze ◽  
Tibor Hortobágyi ◽  
László Módis
Keyword(s):  
Extracellular Matrix ◽  
Growth Factors ◽  
Dermatan Sulfate ◽  
Keratan Sulfate ◽  
Scar Tissue ◽  
Collagen Fibrils ◽  
Proteoglycan Synthesis ◽  
Abnormal Structure ◽  
Fibrillar Collagens ◽  
Corneal Scar

The cornea is the first refractive element of the eye. The transparency of the cornea results from the regularly arranged collagen fibrils, forming lamellar structure and the leucin rich proteoglycans, which make interactions between the fibrils. The adult cornea consists mainly of fibril-forming collagens. The cornea has less amount of fibril associated and non-fibrillar collagens. The main proteoglycans of the cornea are keratan-sulfate proteoglycans and it also contains dermatan-sulfate proteoglycans. Disorders of the proteoglycan synthesis lead to the disruption of the unique pattern and result in thicker collagen fibrils. The abnormal structure of the extracellular matrix can generate corneal disorders and the loss of corneal transparency. Furthermore, proteoglycans and collagens have an important role in wound healing. In injury the keratocytes produce higher amounts of collagens and proteoglycans mediated by growth factors. Depending on the ratio of the cells and growth factors the extracellular matrix returns to normal or corneal scar tissue develops. Orv. Hetil., 2016, 157(25), 995–999.

scholarly journals Extracellular Matrix Deposition and Remodeling after Corneal Alkali Burn in Mice

2021 ◽  
Vol 22 (11) ◽  
pp. 5708
Author(s):  
Kazadi N. Mutoji ◽  
Mingxia Sun ◽  
Garrett Elliott ◽  
Isabel Y. Moreno ◽  
Clare Hughes ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Dermatan Sulfate ◽  
Temporal Distribution ◽  
Keratan Sulfate ◽  
Collagen Fibrils ◽  
Type I ◽  
Chemical Injury ◽  
Matrix Deposition ◽  
Alkali Burn ◽  
Extracellular Matrix Deposition

Corneal transparency relies on the precise arrangement and orientation of collagen fibrils, made of mostly Type I and V collagen fibrils and proteoglycans (PGs). PGs are essential for correct collagen fibrillogenesis and maintaining corneal homeostasis. We investigated the spatial and temporal distribution of glycosaminoglycans (GAGs) and PGs after a chemical injury. The chemical composition of chondroitin sulfate (CS)/dermatan sulfate (DS) and heparan sulfate (HS) were characterized in mouse corneas 5 and 14 days after alkali burn (AB), and compared to uninjured corneas. The expression profile and corneal distribution of CS/DSPGs and keratan sulfate (KS) PGs were also analyzed. We found a significant overall increase in CS after AB, with an increase in sulfated forms of CS and a decrease in lesser sulfated forms of CS. Expression of the CSPGs biglycan and versican was increased after AB, while decorin expression was decreased. We also found an increase in KS expression 14 days after AB, with an increase in lumican and mimecan expression, and a decrease in keratocan expression. No significant changes in HS composition were noted after AB. Taken together, our study reveals significant changes in the composition of the extracellular matrix following a corneal chemical injury.

scholarly journals Glycosaminoglycan–Protein Interactions: The First Draft of the Glycosaminoglycan Interactome

2020 ◽  
pp. 002215542094640 ◽  
Author(s):  
Sylvain D. Vallet ◽  
Olivier Clerc ◽  
Sylvie Ricard-Blum
Keyword(s):  
Extracellular Matrix ◽  
Protein Interactions ◽  
Dermatan Sulfate ◽  
Protein Complexes ◽  
Keratan Sulfate ◽  
Protein Interaction Networks ◽  
Interaction Networks ◽  
Matrix Proteins ◽  
Matrix Assembly ◽  
Gag Protein

The six mammalian glycosaminoglycans (GAGs), chondroitin sulfate, dermatan sulfate, heparin, heparan sulfate, hyaluronan, and keratan sulfate, are linear polysaccharides. Except for hyaluronan, they are sulfated to various extent, and covalently attached to proteins to form proteoglycans. GAGs interact with growth factors, morphogens, chemokines, extracellular matrix proteins and their bioactive fragments, receptors, lipoproteins, and pathogens. These interactions mediate their functions, from embryonic development to extracellular matrix assembly and regulation of cell signaling in various physiological and pathological contexts such as angiogenesis, cancer, neurodegenerative diseases, and infections. We give an overview of GAG–protein interactions (i.e., specificity and chemical features of GAG- and protein-binding sequences), and review the available GAG–protein interaction networks. We also provide the first comprehensive draft of the GAG interactome composed of 832 biomolecules (827 proteins and five GAGs) and 932 protein–GAG interactions. This network is a scaffold, which in the future should integrate structures of GAG–protein complexes, quantitative data of the abundance of GAGs in tissues to build tissue-specific interactomes, and GAG interactions with metal ions such as calcium, which plays a major role in the assembly of the extracellular matrix and its interactions with cells. This contextualized interactome will be useful to identify druggable GAG–protein interactions for therapeutic purpose:

scholarly journals Localization of hyaluronic acid in human articular cartilage.

1994 ◽  
Vol 42 (4) ◽  
pp. 513-522 ◽  
Author(s):  
A Asari ◽  
S Miyauchi ◽  
S Kuriyama ◽  
A Machida ◽  
K Kohno ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Hyaluronic Acid ◽  
Articular Cartilage ◽  
Dermatan Sulfate ◽  
Keratan Sulfate ◽  
Human Articular Cartilage ◽  
Middle Zone ◽  
Deep Zone ◽  
Weak Staining ◽  
Pre Treatment

To demonstrate localization of hyaluronic acid (HA) in articular cartilage of the human femur, biotinylated HA-binding region, which specifically binds HA molecules, was applied to the tissue. In sections fixed by 2% paraformaldehyde-2% glutaraldehyde, HA staining was detected in lamina splendens and chondrocytes in the middle zone. By pretreatment with trypsin, intense HA staining appeared in the extracellular matrix of the deep zone and weak staining in the superficial and middle zones. Moreover, pre-treatment with chondroitinase ABC (CHase ABC) intensely enhanced the stainability for HA in the superficial and middle zones and weakly in the deeper zone. Combined pre-treatment of trypsin with CHase ABC abolished intra- and extracellular staining for HA in all zones. By microbiochemical study, the concentrations of HA and dermatan sulfate were high in the middle zone, whereas those of chondroitin sulfate and keratan sulfate were high in the deep zone. These results suggest that HA is abundantly synthesized in and secreted from the chondrocytes, particularly in the middle zone, whereas it is largely masked by proteoglycan constituents in the extracellular matrix.

Influence of Ionic Concentration on Swelling Behavior and Shear Properties of the Bovine Cornea

2012 ◽  
Author(s):  
Hamed Hatami-Marbini ◽  
Ebitimi Etebu
Keyword(s):  
Extracellular Matrix ◽  
Dermatan Sulfate ◽  
Core Protein ◽  
Incident Light ◽  
Corneal Stroma ◽  
Ionic Concentration ◽  
Collagen Fibers ◽  
Collagen Fibrils ◽  
Knock Out ◽  
Free Ions

The mechanical properties and structure of connective tissues such as the cornea and the cartilage are derived from the functions and properties of their extracellular matrix, a polyelectrolyte gel composed of collagenous fibers embedded in an aqueous matrix. The collagen fibers in the extracellular matrix of the corneal stroma are arranged in regular lattice structures, which is necessary for corneal transparency and transmitting the incident light to the back of the eye. This regular pseudo hexagonal arrangement is attributed to the interaction of collagen fibers with the proteoglycans as these regularities are lost in knock-out mice [i]. Proteoglycans (PGs) are heavily glycosylated glycoproteins. They consist of a core protein to which is glycosaminoglycan chains are covalently attached. The main PG in the corneal stroma is the proteoglycan decorin. Decorin is the simplest small leucine-rich PG and only has a single glycosaminoglycan side chain. It has a horse shape core protein and binds collagen fibrils at regular sites. Chondroitin sulfate (CS), dermatan sulfate (DS), keratan sulfate (KS) are among the prevalent glycosaminoglycans found in the cornea. Under physiological conditions, these linear carbohydrate polymers are ionized and carry negative charges due to the presence of negatively charged carboxylate and sulfate groups. Therefore, a hydrated gel is formed in the empty space between collagen fibrils by attracting water. The interaction of negatively charged glycosaminoglycans with themselves and their interaction with the free ions contribute to the corneal swelling pressure and subsequently to its compressive stiffness. From structural view point, the corneal stroma is a composite polyelectrolyte system in which the observed regular spacings of the collagens are suggested to exist because of the structural interaction of collagens, negatively charged glycosaminoglycans, and the free ions in the interfibrillar space.

scholarly journals Pathobiochemistry of arthrofibrotic remodeling

2017 ◽  
Vol 5 (4_suppl4) ◽  
pp. 2325967117S0015
Author(s):  
Isabel Faust ◽  
Philipp Traut ◽  
Cornelius Knappe ◽  
Doris Hendig
Keyword(s):  
Extracellular Matrix ◽  
Cardiac Fibrosis ◽  
Mechanical Strain ◽  
Inflammatory Cells ◽  
Scar Tissue ◽  
Proteoglycan Synthesis ◽  
Synthesis Rate ◽  
Matrix Remodeling ◽  
Therapeutic Approaches ◽  
Extracellular Matrix Components

Aims and Objectives: Arthrofibrosis is defined as painful impairment of joint flexibility due to fibrotic tissue remodeling after joint trauma or surgery. The incidence of arthrofibrosis after knee replacement surgery is 5 to 10%. Although conventional therapeutic approaches as for instance mobilization and physiotherapy are applied, an effective and causative therapeutic regimen is not known. Materials and Methods: To characterize arthrofibrotic remodeling of the extracellular matrix, to develop new therapeutic approaches and to define diagnostic biomarkers and therapeutic targets, understanding of biochemical principles is urgently required. Fibrotic remodeling was described in several tissues, whereas synovial fibrosis is one of the least investigated fibrotic disorders. Nevertheless, molecular key events in fibrosis seem to be the same and are initiated by exogenic or endogenic tissue damage and differentiation of resident fibroblasts of the connective tissue to myofibroblasts. Known inductors of myofibroblast differentiation are fibrotic growth factors, which are secreted by platelets, damaged tissue and inflammatory cells, as well as mechanical strain. Research studies concerning cardiac fibrosis in tako-tsubo cardiomyopathy also define emotional stress and sympathicotonic destabilization as profibrotic stressors. Myofibroblasts generate contractile forces and synthesize extracellular matrix components, so that scar tissue accumulates. While myofibroblasts disappear by apoptosis in physiological wound healing, they persist in fibrosis. Results: Recently, we could demonstrate that increased expression of human xylosyltransferase (XT)-I, an enzyme which catalyzes the rate limiting step in proteoglycan glycosylation, is linked to abnormal extracellular matrix remodeling. Serum XT activity reflects proteoglycan synthesis rate and is known as fibrosis biomarker in liver fibrosis or scleroderma. Our data also indicate that XT-I is a cellular key mediator of arthrofibrosis. However, we suggest that molecular changes based on arthrofibrosis are, due to local restriction of the affected joint by the blood-synovial-barrier, not detectable in human serum. Currently, we study synovial XT activity of arthrofibrosis patients and controls in a multicenter study. Conclusion: In summary, we give insights into the complex pathobiochemistry of arthrofibrosis as well as current research projects. A deeper characterization of the involved mechanisms might not only contribute to control and inhibit fibrotic remodeling by interfering with components of fibrotic signal cascades but also to establish new therapeutic strategies.

scholarly journals Immunolocation analysis of glycosaminoglycans in the human growth plate.

1992 ◽  
Vol 40 (2) ◽  
pp. 275-282 ◽  
Author(s):  
S Byers ◽  
B Caterson ◽  
J J Hopwood ◽  
B K Foster
Keyword(s):  
Extracellular Matrix ◽  
Growth Plate ◽  
Dermatan Sulfate ◽  
Human Growth ◽  
Keratan Sulfate ◽  
The Other ◽  
Hypertrophic Chondrocytes ◽  
Proliferative Zone ◽  
Metabolic Products ◽  
Metaphyseal Bone

Monoclonal antibodies were used in this study to immunolocate glycosaminoglycans throughout the human growth plate. Chondroitin-4-sulfate, chondroitin-6-sulfate, and keratan sulfate were observed in the extracellular matrix of all zones of the growth plate and persisted into the cartilage trabeculae of newly formed metaphyseal bone. Also present in the extracellular matrix was an oversulfated chondroitin/dermatan sulfate glycosaminoglycan which appeared to be specific to the proliferative and hypertrophic zones of the growth plate. As with the other extracellular matrix molecules, this epitope persisted into the cartilage trabeculae of the metaphyseal bone. Zonal differences between the extracellular and pericellular or lacunae matrix were also observed. The hypertrophic chondrocytes appeared to synthesize chondroitin sulfate chains containing a non-reducing terminal 6-sulfated disaccharide, which were located in areas immediately adjacent to the cells. This epitope was not found to any significant extent in the other zones. The pericellular region around hypertrophic chondrocytes also contained a keratan sulfate epitope which was also observed in the resting zone but not in the proliferative zone. These cell-associated glycosaminoglycans were not found in the cartilage trabeculae of metaphyseal bone, indicating their removal as the terminal hypertrophic chondrocytes and their lacunae are removed by invading blood vessels. These changes in matrix glycosaminoglycan content, both in the different zones and within zones, indicate constant subtle alterations in chondrocyte metabolic products as they proceed through their life cycle of proliferation, maturation, and hypertrophy.

Hydration Effects on Tensile Properties of the Corneal Stroma

2013 ◽  
Author(s):  
Abdolrasol Rahimi ◽  
Hamed Hatami-Marbini
Keyword(s):  
Tensile Properties ◽  
Dermatan Sulfate ◽  
Lattice Structure ◽  
Corneal Thickness ◽  
Corneal Stroma ◽  
Swelling Pressure ◽  
Keratan Sulfate ◽  
Empty Space ◽  
Collagen Fibrils ◽  
Healthy Human

The mechanical behavior of the cornea is mainly governed by the microstructure and composition of the stroma. The stroma is a highly ordered extracellular matrix and constitutes about 90% of the corneal thickness. From the mechanics point of view, the corneal stroma can be considered as a polyelectrolyte gel which is composed of collagen fibrils embedded in an aqueous matrix. The collagen fibrils compose about 70% of cornea’s dry mass and are arranged in a regular lattice structure [2]. Previous studies have shown that while the collagen fibrils are primarily located parallel to the surface, they are not distributed uniformly in all directions and their preferred orientation is not same in different species. For example, collagen fibrils are almost equally distributed in the nasal-temporal and inferior-superior directions in healthy human corneas [4] and they are mainly aligned in the inferior-superior direction in bovine corneas[2]. The differences in the orientations of the collagen fibrils have seen to have important implications on the mechanical properties of the cornea. In addition to this observation, the relative distance between the collagen fibrils is expected to play a role in defining the mechanics of the tissue. It is well-documented that the proteoglycans bind collagen fibrils at regular sites and control their relative position. The main proteoglycan in the corneal stroma is decorin. Decorin is the simplest small leucine-rich proteoglycan with a single glycosaminoglycan side chain. Chondroitin sulfate, dermatan sulfate, and keratan sulfate are among the prevalent glycosaminoglycans found in the cornea. Under physiological conditions, these linear carbohydrate polymers are ionized and carry negative charges. Therefore, a hydrated gel is formed in the empty space between collagen fibrils by attracting water. It is known that the interaction of these negatively charged glycosaminoglycans with themselves and with the free ions contribute to the corneal swelling pressure and subsequently to its compressive stiffness. Nevertheless, their possible influence on the corneal tensile properties is yet to be determined. In this work, we experimentally characterized the tensile properties of the bovine corneal stroma in different bathing solutions. Furthermore, a quasi-linear viscoelastic (QLV) model was used to examine the effect of bathing fluids and corneal hydration on mechanical parameter of the cornea.

beta-D xyloside alters dermatan sulfate proteoglycan synthesis and the organization of the developing avian corneal stroma

Development ◽  
1992 ◽  
Vol 115 (2) ◽  
pp. 383-393
Author(s):  
R.A. Hahn ◽  
D.E. Birk
Keyword(s):  
Collagen Fibril ◽  
Dermatan Sulfate ◽  
Corneal Stroma ◽  
Small Diameter ◽  
Keratan Sulfate ◽  
Proteoglycan Synthesis ◽  
Sulfate Proteoglycan ◽  
In Ovo ◽  
Dermatan Sulfate Proteoglycan ◽  
Fibril Diameter

Corneal transparency is dependent upon the development of an organized extracellular matrix containing small diameter collagen fibrils with regular spacing, organized as orthogonal lamellae. Proteoglycan-collagen interactions have been implicated in the regulation of collagen fibrillogenesis and matrix assembly. To determine the role of dermatan sulfate proteoglycan in the development and organization of the secondary corneal stroma, its synthesis was disrupted using beta-D xyloside. The secondary corneal stroma contains two different proteoglycans, dermatan sulfate and keratan sulfate proteoglycan. beta-D xyloside interferes with xylose-mediated O-linked proteoglycan synthesis, and thus disrupts dermatan sulfate proteoglycan synthesis. Corneal keratan sulfate proteoglycan, a mannose-mediated N-linked proteoglycan, should not be altered. Biochemical analysis of corneas treated both in vitro and in ovo revealed a reduced synthesis of normally glycosylated dermatan sulfate proteoglycans and an increased synthesis of free xyloside-dermatan sulfate glycosaminoglycans. Keratan sulfate proteoglycan synthesis was unaltered in both cases. Corneal stromas were studied using histochemistry and electron microscopy after in ovo treatment with beta-D xyloside. The observed biochemical alterations in dermatan sulfate proteoglycans translated into disruptions in the organization of beta-D xyloside-treated stromas. There was a reduction in the histochemical staining of proteoglycans, but no alteration in collagen fibril diameter. In addition, focal alterations in collagen fibril packing, and a disruption of lamellar organization were observed in beta-D xyloside-treated corneas. These data suggest that dermatan sulfate proteoglycans are not involved in the regulation of corneal collagen fibril diameter, but are important in the fibril-fibril spacing as well as in lamellar organization, and cohesiveness.

scholarly journals An Immunohistochemical Study of the Rabbit Suprapatella, a Sesamoid Fibrocartilage in the Quadriceps Tendon Containing Aggrecan

2002 ◽  
Vol 50 (7) ◽  
pp. 955-960 ◽  
Author(s):  
T. Tischer ◽  
S. Milz ◽  
M. Maier ◽  
M. Schieker ◽  
M. Benjamin
Keyword(s):  
Extracellular Matrix ◽  
Dermatan Sulfate ◽  
Keratan Sulfate ◽  
Quadriceps Tendon ◽  
Joint Fluid ◽  
Knee Joints ◽  
Significant Finding ◽  
Link Protein ◽  
Vastus Intermedius ◽  
Human Joints

The rabbit suprapatella is a sesamoid fibrocartilage in the deep surface of the tendon of vastus intermedius and an integral part of the knee joint. We report the presence of a variety of proteoglycans (aggrecan and versican), glycosaminoglycans (chondroitin 4 and 6 sulfate, dermatan sulfate, keratan sulfate) and glycoproteins (tenascin) in its extracellular matrix and the intermediate filament vimentin in the fibrocartilage cells. The most significant finding is the presence of aggrecan in the extracellular matrix, along with its associated link protein and several of its integral glycosaminoglycans. Aggrecan probably enables the suprapatella to withstand compression. Although it can be assumed that aggrecan metabolites detected in synovial fluid from some human joints are predominantly associated with articular hyaline cartilage, the presence of aggrecan in the rabbit suprapatella means that this cannot be assumed for all animal knee joints. We conclude that it is important for orthopedic researchers who use animal models for arthritis research to check for the presence of a suprapatella when joint fluid analyses are interpreted.

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