Structural characterization of human alveolar bone proteoglycans

X-linked diseases: susceptible females

The role of X-inactivation is often ignored as a prime cause of sex differences in disease. Yet, the way males and females express their X-linked genes has a major role in the dissimilar phenotypes that underlie many rare and common disorders, such as intellectual deficiency, epilepsy, congenital abnormalities, and diseases of the heart, blood, skin, muscle, and bones. Summarized here are many examples of the different presentations in males and females. Other data include reasons why women are often protected from the deleterious variants carried on their X chromosome, and the factors that render women susceptible in some instances.

Comparisons of the chondroitin sulphate levels in orthodontically moved canines and the clinical outcomes between two different force magnitudes

The aims of this study were to compare the chondroitin sulphate (CS) levels in gingival crevicular fluid (GCF) of moved canines using either 70 or 120 g of orthodontic force, and to compare the rate of tooth movement and the amount of pain between these two force magnitudes. Sixteen patients (6 males and 10 females; aged 16.91 ± 2.99 years), with class I malocclusion, who required orthodontic treatment with first premolar extractions, were recruited. The force magnitudes used to move the maxillary canines distally were controlled at 70 and 120 g on the right and the left sides, respectively. GCF samples were collected with Periopaper(®) strips before and during orthodontic tooth movement. Competitive ELISA with monoclonal antibody was used to measure the CS levels. The distance of tooth movement and the amount of pain assessed by visual analog scale (VAS) scores were evaluated. The medians of CS levels during the loaded period were significantly greater than those during the unloaded period (P < 0.05). The differences between the medians of CS levels of 70 g and 120 g retraction force during each 1 week period were not significant. There was no significant difference in the rates of canine movement between these two force magnitudes. However, using 120 g, the medians of VAS scores were significantly greater than those with 70 g (P < 0.05). Collectively, 70 g retraction force appears to be sufficient and more suitable than 120 g force as it causes no difference in biochemically-assessed bone remodelling activity, the same rate of tooth movement, reduced pain and better comfort.

Absorption-based assays for the analysis of osteogenic and chondrogenic yield

The typical characteristics of cartilage and bone tissue are their unique extracellular matrices on which our body relies for structural support. In the respective tissue, the cells that create these matrices are the chondrocyte and the osteoblast. During in vitro differentiation from an embryonic or any other stem cell, specific cell types must be unequivocally identifiable to be able to draw the conclusion that a specific cell type has indeed been generated. Here, gene expression profiling can be helpful, but examining functional properties of cells is a lot more conclusive. As proteoglycans are found in and are part of the function of cartilage tissue, their detection and quantification becomes an important diagnostic tool in tissue engineering. Likewise, in bone regeneration therapy and in research, alkaline phosphatase is a known marker to detect the degree of development and function of differentiating osteoblasts. Calcification of the maturing osteoblast is the last stage in its development, and thus, the quantification of deposited calcium can aid in determining how many cells in a given culture have successfully matured into fully functioning osteoblasts. This chapter describes methods ideal for testing of proteoglycan content, alkaline phosphatase activity, and calcium deposit during in vitro chondro- and osteogenesis.

Raised chondroitin sulphate WF6 epitope levels in gingival crevicular fluid in chronic periodontitis

AIM

To determine the levels of chondroitin sulphate (CS) WF6 epitope, recognized by WF6 monoclonal antibody, in gingival crevicular fluid (GCF) from different stages of periodontal disease and healthy periodontium, and to correlate those levels with clinical parameters.

MATERIAL AND METHODS

GCF samples, collected from 389 sites, were analysed for the WF6 epitope levels by the competitive enzyme-linked immunosorbent assay.

RESULTS

The median WF6 epitope level was significantly higher in chronic periodontitis sites (n=185) than in healthy and gingivitis sites (n=204) (p<0.001), whereas the median levels did not significantly differ between healthy (n=65) and gingivitis sites (n=139). The median level in severe periodontitis sites (n=60) was significantly higher than that in moderate periodontitis sites (n=63) (p=0.019). Similarly, the median level in moderate periodontitis sites was significantly higher than that in slight periodontitis sites (n=62) (p=0.001). The WF6 epitope levels significantly correlated with probing depth (r=0.777, p=0.001) and loss of clinical attachment level (r=0.814, p=0.001).

CONCLUSION

Elevated CS WF6 epitope levels in GCF are associated with severity of periodontitis. The WF6 antibody may therefore be clinically applied to monitor disease severity and progression.

Lipopolysaccharide alters decorin and biglycan synthesis in rat alveolar bone osteoblasts: consequences for bone repair during periodontal disease

A prime pathogenic agent associated with periodontitis is lipopolysaccharide (LPS) derived from Porphyromonas gingivalis. This study investigated the effects of P. gingivalis LPS on osteoblasts, which are responsible for alveolar bone repair. Bone cells were obtained from explants of rat alveolar bone chips and cultured with 0–200 ng ml⁻¹ of P. gingivalis LPS. Porphyromonas gingivalis LPS significantly increased cell proliferation and inhibited osteoblast differentiation, as judged by reduced alkaline phosphatase activity. Analysis of biglycan mRNA and protein levels indicated that P. gingivalis LPS significantly delayed the normally high expression of biglycan during the early stages of culture, which are associated with cell proliferation and early differentiation of progenitor cells. In the presence of P. gingivalis LPS, decorin expression by the alveolar bone cells was reduced during periods of culture relating to collagen fibrillogenesis and mineral deposition. Analysis of glycosaminoglycan chains conjugated to these proteoglycans suggested that in the presence of P. gingivalis LPS, dermatan sulfate persisted within the matrix. This study suggests that P. gingivalis LPS influences the expression and processing of decorin and biglycan in the matrix, altering alveolar bone cell activity and osteoblast phenotype development. The consequences of this altered expression in relation to hindering bone repair as part of the cycle of events during periodontal disease are discussed.

Reactive oxygen species and human inflammatory periodontal diseases

Reactive oxygen species (ROS) have emerged as important signaling molecules in the regulation of various cellular processes. They can be generated by the mitochondrial electron transport chain in mitochondria and activation of polymorphonuclear leukocytes (PMN) during inflammatory conditions. Excessive generation of ROS may result in attack of and damage to most intracellular and extracellular components in a living organism. Moreover, ROS can directly induce and/or regulate apoptotic and necrotic cell death. Periodontal pathologies are inflammatory and degenerative diseases. Several forms of periodontal diseases are associated with activated PMN. Damage of tissues in inflammatory periodontal pathologies can be mediated by ROS resulting from the physiological activity of PMN during the phagocytosis of periodontopathic bacteria.

Immunohistochemical characterization of noncollagenous matrix molecules on the alveolar bone surface at the initial principal fiber attachment in rat molars

This study was designed to immunodetect proteoglycans (PGs) and the noncollagenous glycoproteins, bone sialoprotein (BSP) and osteopontin (OPN) on developing alveolar bone surface in rat molars by the indirect immunoperoxidase method, and to discuss the roles of these molecules at the initial principal fiber (PF) attachment. To characterize PGs, antibodies against five species of glycosaminoglycans (GAGs), chondroitin-4-sulfate (C4S), chondroitin-6-sulfate (C6S), unsulfated chondroitin (C0S), dermatan sulfate (DS), and keratan sulfate (KS) were used. Maxillary alveolar bone facing the distal root of the second molar was examined in 20- and 25-day-old male Wistar rats. Routine histological staining was also used. A hematoxylin-stained, fibril-poor layer always appeared on the alveolar bone surface just prior to the initial PF organization. This layer was strongly immunoreactive for C4S, C0S, OPN, and BSP, and weakly for C6S, but not for DS and KS. Then the initial PFs were attached to this layer. When new bone containing Sharpey's fibers covered this layer, it remained as a hematoxylin-stained, fibril-poor layer between Sharpey's fiber-containing and -lacking bone. The layer was consistently immunoreactive for OPN and BSP but had no immunoreactivity for GAGs. The results suggest that the accumulation of C4S-, C0S-, and C6S-carrying PGs, and of BSP and OPN is a primary event at the initial PF attachment, and is involved in the adhesion of PFs and mineralization of the initial attachment layer. The BSP and OPN act to maintain the interface integrity between Sharpey's fiber-containing and Sharpey's fiber-lacking alveolar bone after the PF attachment is established.

Changing profiles of proteoglycans in the transition of predentine to dentine

Proteoglycans and their constituent glycosaminoglycans have been proposed to play important roles in matrix mediated formation of mineralised tissues, such as dentine. This study has examined the changing profile of proteoglycan species during the transition of unmineralised predentine to mineralised dentine. Three-week-old calves teeth were collected and proteoglycans purified from the predentine, the predentine/dentine interface and dentine. Decorin and biglycan, together with related degradation products, were identified in the predentine fraction, alongside degradation products of versican, indicating metabolism of the proteoglycan components within this tissue. Decorin and biglycan were also identified as major proteoglycan species within extracts from the predentine/dentine interface and dentine. Analysis of the glycosaminoglycan constituents within each fraction demonstrated significant changes in their composition. Predentine contained a high proportion of dermatan sulfate (DS) (51.5%), with chondroitin sulfate (CS) (17.8%) and hyaluronan (HA) (30.7%) additionally identified. Within the predentine/dentine interface the proportion of CS increased greatly (62.5%), with corresponding decrease in the proportion of DS (21.4%) and HA (16.1%) also evident. CS only was identifiable within the dentine matrix. A four-fold increase in the level of sulfation was identified for glycosaminoglycans extracted from the predentine/dentine interface compared with the predentine and dentine fraction. The ratio of DeltaDi4S:DeltaDi6S was higher for glycosaminoglycans isolated from the predentine fraction. Glycosaminoglycans extracted from the dentine fraction possessed longer chain lengths than those present in the predentine and predentine/dentine fractions. The results indicate that the proteoglycans within each fraction undergo subtle structural modification, particularly at the onset of mineralisation, indicating an active involvement of these macromolecules in the overall mineralisation process.

Differential distribution of glycosaminoglycans in human cementifying fibroma and fibro-osseous lesions

OBJECTIVE

Differential diagnosis of cementifying fibroma, ossifying fibroma and fibrous dysplasia by histological evaluation is often difficult. The aim of this study was to examine the immunoreactivities for keratan sulfate (KS) and chondroitin-4-sulfate (C4S) glycosaminoglycans of the histological samples obtained from mandibles of patients with these diseases.

MATERIALS AND METHODS

The samples were collected from three patients with cementifying fibroma, two with ossifying fibroma and three with fibrous dysplasia and were subjected to immunohistochemical analyses.

RESULTS

The results demonstrated that a significant immunoreactivity for KS was found in lacunae housing cells in the cementum-particles of cementifying fibromas, while both ossifying fibromas and fibrous dysplasias showed no significant immunoreactivity for KS. For C4S, while the former showed little immunoreactivity, the latter two cases exhibited intensive immunostaining in the pre- and poorly mineralized matrices.

CONCLUSIONS

These results suggest that cementifying fibromas could be distinguished from these fibro-osseous tumors by using immunohistochemical analysis for KS and C4S.

Mediators of periodontal osseous destruction and remodeling: principles and implications for diagnosis and therapy

Osteoclastic bone resorption is a prominent feature of periodontal disease. Bone resorption via osteoclasts and bone formation via osteoblasts are coupled, and their dysregulation is associated with numerous diseases of the skeletal system. Recent developments in the area of mediators of osteoclastic differentiation have expanded our knowledge of the process of resorption and set the stage for new diagnostic and therapeutic modalities to treat situations of localized bone loss as in periodontal disease. This review describes the current state of knowledge of osteoclast differentiation and activity, mediators, and biochemical markers of bone resorption and their use and potential use in clinical periodontics. Finally, therapeutic strategies based on knowledge gained in the treatment of metabolic bone diseases and in periodontal clinical trials are discussed, and the potential for future strategies is proposed relative to their biologic basis. The intent is to update the field of periodontics on the current state of pathophysiology of the osteoclastic lesion and outline diagnostic and therapeutic strategies with a rational basis in the underlying biology.

The interaction of recombinant decorin with alpha2HS-glycoprotein-implications for structural and functional investigations

Isolated protein preparations of the small leucine-rich proteoglycans (SLRPs) associated with mineralized tissues have provided important information in understanding their structural and functional interactions within extracellular matrices and their potential roles in mineralization. Two important SLRPs, decorin and biglycan, copurify following extraction and purification from mineralized tissues using standard procedures, and to overcome this problem decorin was synthesized within a mammalian expression system to obtain pure preparations. The expressed protein was purified from the culture medium using anion-exchange chromatography, and characterization confirmed the presence of a decorin-rich fraction. However, N-terminal sequencing revealed the additional presence of alpha2HS-glycoprotein (alpha2HSG), representing approximately 35% of the total purified fraction. The decorin-rich fraction was subjected to selected further purification techniques to separate decorin from alpha2HSG. Application of the sample at a low concentration (1 mg/ml) to a second anion-exchange procedure and elution over an expanded sodium chloride gradient resulted in a high degree of purity (98%), with a single protein isolate demonstrable by SDS-PAGE. Electroelution achieved partial purification ( approximately 89%), but immunoprecipitation with antibodies against the glycosaminoglycan chain and the polyhistidine tag failed to separate the two proteins. This study suggests there is a strong interaction between recombinantly produced decorin and alpha2 HSG and highlights the importance of the purification technique to the application of recombinantly produced proteins or those that have been extracted from mineralized tissues for use in structural and functional interactions.

Inhibition of hydroxyapatite crystal growth by bone proteoglycans and proteoglycan components

The small leucine-rich proteoglycans (SLRPs) interact with hydroxyapatite (HAP) and have been demonstrated to be important modulators of mineralisation. In the present study we have examined the effect of bone SLRPs, purified bone glycosaminoglycan (GAG) chains and core proteins as well as commercial chondroitin 4-sulphate, chondroitin 6-sulphate and desulphated chondroitin on HAP crystal growth. Seeded HAP growth experiments revealed that addition of bone GAG chains resulted in almost complete inhibition of crystal growth (93%), with addition of core proteins and intact PGs resulting in 55 and 37% inhibition, respectively. In contrast, commercial chondroitin 4-sulphate was significantly less inhibitory compared with the bone SLRPs and components, yielding only a 6% reduction in HAP-induced crystal growth at the same concentration. Significantly, chondroitin 6-sulphate was found to be noninhibitory, whilst desulphated chondroitin was inhibitory to seeded HAP growth. The data indicate that direct adsorption of SLRPs to growth sites and their ability to bind calcium are significant determinants in the inhibitory process. In addition, PG/GAG chemistry and the conformation of the macromolecules in solution have also been shown to be important. This work provides new information regarding the role of bone SLRPs and their components in the regulation of the mineralisation process.

Interaction of glucuronic acid and iduronic acid-rich glycosaminoglycans and their modified forms with hydroxyapatite

Proteoglycans and their spatial arms, glycosaminoglycans (GAGs), are known to interact with hydroxyapatite (HAP) and have been implicated as important modulators of mineralisation. In the present study isotherm data (0.02 M sodium acetate, pH 6.8) revealed that the iduronic-rich GAGs heparan sulphate, heparin and dermatan sulphate showed greater binding onto HAP with higher adsorption maxima compared with the glucuronic acid-rich GAGs chondroitin-4-sulphate, chondroitin-6-sulphate and hyaluronan. Chemically desulphated chondroitin showed no adsorption onto HAP. With the exception of hyaluronan, the GAGs studied showed no desorbability in sodium acetate buffer only, whereas in di-sodium orthophosphate, desorption occurred much more readily. The data indicates that GAG chemistry and conformation in solution greatly influence the interaction of these molecules with HAP. The conformational flexibility of iduronic acid residues may be an important determinant in the strong binding of iduronic acid-rich GAGs to HAP, increasing the possibility of the appended anionic groups matching calcium sites on the HAP surface, compared with more rigid glucuronic acid residues. This work provides important information concerning interfacial adsorption phenomena between the organic-inorganic phases of mineralised systems.

Interaction of bone proteoglycans and proteoglycan components with hydroxyapatite

The small leucine-rich proteoglycans (SLRPs) of bone interact with hydroxyapatite (HAP) and are proposed to play an important role in the regulation of the mineralisation process. The present study has examined the interaction of bone SLRPs, purified, liberated bone glycosaminoglycan (GAG) chains and core proteins, as well as commercial chondroitin 4-sulphate (C4S) with HAP. Isotherm data (0.02 M sodium acetate) revealed that the intact proteoglycans (PGs) and bone GAGs showed greater binding onto HAP with higher adsorption maxima than the constituent core proteins and commercial C4S. Adsorption was dependent on pH and ionic strength, increasing with decreasing pH and in the presence of calcium whilst decreasing in the presence of phosphate, suggesting that electrostatic effects are important. The data indicates that PG/GAG chemistry and conformation in solution are significant determinants in the adsorption process and provides important information concerning interfacial adsorption phenomena between the organic-inorganic phases of mineralised systems.

Proteoglycans and orthodontic tooth movement

Proteoglycans represent an important and diverse family of extracellular matrix components within the connective tissues of the periodontium. This review focuses on the function and metabolism of the various proteoglycans in periodontal tissues, such as alveolar bone and periodontal ligament, and considers their potential fate in response to an orthodontic force. Such considerations provide an important background in evaluating the potential for proteoglycan metabolites, alongside other connective tissue metabolites, as biomarkers for assessing the deep-seated metabolic changes and as a diagnostic tool in monitoring orthodontic tooth movement.

Glycosaminoglycans in peri-implant sulcus fluid from implants placed in sinus-inlay bone grafts

Glycosaminoglycans (GAG) present in peri-implant sulcus fluid (PISF) were used as an indicator of the metabolic activity in the supporting tissues of implants placed in maxillary bone or maxillary bone and bone grafts together. The study included 16 patients who received implants (Brånemark system(R)) and sinus-inlay bone grafts. In 12 of these patients, the implants were placed in either maxillary bone alone or maxillary bone and sinus-inlay bone grafts in combination. Altogether the patients received a total of 102 implants, of which 73 implants were placed in bone grafts and 29 implants in maxillary bone alone. Samples of PISF were tested at 2-8 days and at 6 months after abutment connection. Levels of the GAG's chondroitin-4-sulphate (C4S) and hyaluronan (HA) were assessed using cellulose acetate electrophoresis and densitometric scanning of Alcian blue-stained strips against known GAG standards. The C4S was used as a bone metabolic marker, and HA was used to reflect the progress of soft tissue healing. Comparing grafted and non-grafted regions, there was no significant difference in either C4S levels or HA levels during the first 8 days or at the 6 months period. The levels of HA from the first week collection did not differ significantly from the HA level after 6 months in either type of bone. However, the level of C4S was significantly lower after 6 months than during the first week, in both maxillary and grafted bone but consistent with a normal metabolic turnover. C4S can therefore be used as an indicator of the progressive healing of bone adjacent to implants.

The isolation and detection of non-collagenous proteins from the compact bone of the dinosaur Iguanodon

This report describes the isolation of guanidinium chloride extractable protein from demineralised bone extracts obtained from the 125-130 mya dinosaur Iguanodon. Protein products were isolated in the Mr. range 5,000-66,000 using SDS-PAGE and represent the first electrophoretically defined proteins isolated from dinosaur tissues. The levels of glycine, aspartate and serine tentatively suggest the presence of phosphoproteins. Hydroxylysine and hydroxyproline were not detected, confirming the presence of non-collagenous material. In addition the absence of ornithine confirmed lack of bacterial contamination. The relatively high level of leucine in the 2MNaCl NaCl fractions together with the abolition of alcian blue reactivity following protease-free chondroitinase digestion suggests the presence of proteoglycans. The study is of interest in describing the early proteins laid down in mineralised tissues for epitactic crystal growth and may provide evidence on evolutionary aspects of bone proteins.

Reactive oxygen species: a potential role in the pathogenesis of periodontal diseases

The pathological events leading to the destruction of the periodontium during inflammatory periodontal diseases are likely to represent complex interactions involving an imbalance in enzymic and non-enzymic degradative mechanisms. This paper aims to review the increasing body of evidence implicating reactive oxygen species (ROS), derived from many metabolic sources, in the pathogenesis of periodontal tissue destruction. ROS are generated predominantly by polymorphonuclear leukocytes (PMN) during an inflammatory response and are regarded as being highly destructive in nature. The detection of ROS oxidation products, the elevation of iron and copper ions, which catalyse the production of the most reactive radical species, and the identification of an imbalance in the oxidant/antioxidant activity within periodontal pockets, suggests a significant role for ROS in periodontal tissue destruction. In vitro studies have shown that ROS are capable of degrading a number of extracellular matrix components including proteoglycans, resulting in the modification of amino acid functional groups, leading to fragmentation of the core protein, whilst the constituent glycosaminoglycan chains undergo limited depolymerisation. The identification and characterisation of connective tissue metabolites in gingival crevicular fluid (GCF) resulting from the degradation of periodontal tissues, notably alveolar bone, provides further evidence for a role for ROS in tissue destruction associated with inflammatory periodontal diseases.

Structural analysis of proteoglycans synthesized by mineralizing bone cells in vitro in the presence of fluoride

This study investigated the biochemical structure of proteoglycans synthesized during matrix maturation by mineralizing bone cells in vitro, in the presence and absence of fluoride. Bone cells were obtained from rat femur washes and cultured in alpha MEM media supplemented with fetal calf serum, ascorbic acid, beta-glycerophosphate and dexamethasone. Cells were characterized as osteoblast-like by the expression of alkaline phosphatase activity and the synthesis of collagen type I and osteocalcin. Fluoride, present in the culture media at concentrations of 10(-5) M or 10(-7) M, had negligible effect on cell viability. However, calcium deposition was increased in cell cultures incubated in the presence of fluoride. Proteoglycans were extracted from the extracellular matrix with 4 M guanidinium chloride and purified by anion exchange chromatography. Biochemical analysis identified the presence of the small leucine rich proteoglycan, decorin and biglycan, in addition to degradation products relating to the larger chondroitin sulphate protoeglycan, versican. Fluoride had little effect on the size or amino acid composition of the protein core, but resulted in significant alterations to the GAG chains, including a dramatic reduction in chain length, reduction in sulphation and decrease in the proportion of dermatan sulphate compared to chondroitin sulphate. The influence of fluoride on proteoglycan structure synthesized by mineralizing bone cells provides valuable information, indicating specific roles for dermatan sulphate and chondroitin sulphate proteoglycans. The results suggested that fluoride affected the post-translational assembly of the GAG chains which may be an influential factor in the mineralization process.

The modification of alveolar bone proteoglycans by reactive oxygen species in vitro

Reactive oxygen species (ROS) are being increasingly implicated in the connective tissue degradation associated with chronic inflammatory conditions, such as periodontal disease. The present study investigated the effects of ROS on the proteoglycans (PG) of alveolar bone which are important structural components within the periodontium. PG were isolated from ovine alveolar bone and exposed to increasing concentrations of hydrogen peroxide (H2O2) or to a hydroxyl radical (.OH) flux for 1 h or 24 h, and the degradation products examined for depolymerisation and chemical modification of the PG structure. ROS were demonstrated to be capable of degrading alveolar bone PG in vitro, the .OH species resulting in greater modification than H2O2. The degradative effects observed included cleavage of the protein core and depolymerisation of the GAG chains. The core proteins were more susceptible to degradation than the GAG chains in the presence of H2O2 alone, although both the core proteins and the GAG chains were extensively degraded in the presence of a .OH flux for both 1 h and 24 h. Exposure of the PG to .OH for 24 h resulted in significant modification to the amino acid composition with decreases in the proportion of leucine and the complete loss of proline, tyrosine and phenylalanine evident. The results highlight the potential role of ROS as an important mechanism in considering the pathology of periodontal tissue destruction.

Immunochemical detection of the proteoglycans decorin and biglycan in human gingival crevicular fluid from sites of advanced periodontitis

This study characterized proteoglycan metabolites present in gingival crevicular fluid (GCF) collected from sites with clinical evidence of advanced periodontal disease. The metabolites were purified by anion-exchange chromatography from which a chondroitin sulphate rich fraction was identified by cellulose acetate electrophoresis. Sodium dodecylsulphate-polyacrylamide gel electrophoresis of this fraction revealed a broad silver-staining band with mol. wt 55-65 k and Western blotting suggested that this band was immunoreactive with CS-56, a monoclonal antibody for chondroitin sulphate. Digestion of the metabolite with chondroitinase ABC (protease-free) led to the loss of the silver-staining band. Dot-blot analysis identified components in this fraction that were immunoreactive for the monoclonal/polyclonal antibodies against the C-termino of decorin and biglycan. Amino acid analysis revealed the composition of the proteoglycan metabolite to be rich in glycine, serine and glutamic acid. Immunochemical and biochemical analyses were compared with those of proteoglycan purified from human alveolar bone. Changes in the amino acid composition were noted, suggesting the proteoglycan metabolite has undergone extensive modification and fragmentation to the protein core. The results suggest that the proteoglycan metabolite from GCF represented a degradation product originating from the active destruction of the alveolar bone. They provide further support for the proposal that the appearance of proteoglycan metabolites in GCF is a biomarker for active destruction of alveolar bone, the biochemical analysis of which provides important information on mechanisms involved in the pathology of periodontal diseases.

Degradation of glycosaminoglycans by reactive oxygen species derived from stimulated polymorphonuclear leukocytes

The effect of reactive oxygen species (ROS), generated by in vitro stimulation of isolated PMN upon the main GAG components of mineralised and non-mineralised connective tissues was investigated. PMN were isolated from whole blood and the production of the ROS superoxide (O2.-) and hydroxyl radicals (.OH) was stimulated by the addition of phorbol myristyl acetate (PMA) and PMA/FeCl3-EDTA chelate respectively and their production assessed over a 24 h period. The glycosaminoglycans (GAG), hyaluronan, chondroitin 4-sulphate and dermatan sulphate, were exposed to the ROS fluxes, incubated at 37 degrees C for 1 h and 24 h. GAG fragmentation was examined by gel exclusion chromatography and modification to hexuronic acid and hexosamine residues determined. Stimulation of PMN with PMA resulted in a burst of O2.- production for 1 h, which was sustained at a reduced level for 24 h. Fragmentation of GAG was observed for all GAG examined. Modification to the GAG was evident, with hyaluronan being more susceptible to loss of GAG residues than sulphated GAG. Modification of sugar residues increased with the incubation time and loss of the hexuronic acid residues was greater than loss of hexosamine residues. Addition of FeCl3-EDTA chelate, which led to the generation of .OH and was sustained over the 24 h period, demonstrated similar trends of GAG modification although increased degradation and loss of hexosamine and hexuronic acid were observed. GAG chains are constituents of PGs and their modification is likely to affect the function of these macromolecules and be of importance in considering the pathogenesis of inflammatory diseases, including periodontal diseases.

Adsorption of chondroitin-4-sulphate and heparin onto titanium: effect of bovine serum albumin

The adsorption of chondroitin-4-sulphate (C4S) and heparin onto titanium has been studied in the absence and presence of bovine serum albumin (BSA). Isotherm data (0.02 M calcium acetate, pH 6.8) have shown that BSA in solution and BSA-coated titanium result in decreased adsorption for both C4S and heparin. For the BSA in solution data, C4S/heparin and BSA may compete for the same sites on the titanium surface via calcium ions, or alternatively in the case of heparin, complexes of heparin and BSA form in solution, leading to less binding due to steric effects. Evidence of an interaction between heparin and BSA in solution has been shown in this study, there being negligible interaction between C4S and BSA. BSA adsorption from solution investigated in the presence of C4S/heparin decreases with increasing C4S/heparin solution concentration. This may be due to a glycosaminoglycan (GAG) induced conformational change of BSA from a compact to an extended structure. The decreased adsorption onto BSA-coated titanium may be due to masking of the GAG binding sites, this effect being greater for C4S. Desorption of BSA from the pre-coated titanium in the presence of C4S and heparin is <10% and <30% respectively, indicating that BSA is strongly bound to the titanium surface.

Adsorption of chondroitin-4-sulphate and heparin onto hydroxyapatite--effect of bovine serum albumin

The adsorption of chondroitin-4-sulphate (C4S) and heparin onto hydroxyapatite (HA) has been studied in the absence and presence of bovine serum albumin (BSA). Isotherm data at pH 6.8 have shown that BSA in solution has no effect on C4S adsorption, whereas heparin affinity and adsorption decrease. These data suggest that C4S and BSA bind to different calcium sites on the HA surface. Heparin and BSA may compete for the same calcium sites, or alternatively form heparin-BSA complexes leading to less binding due to steric effects. Evidence of an interaction between heparin and BSA in solution has been shown in this study, there being negligible interaction for C4S. BSA adsorption from solution onto HA decreases with increasing C4S/heparin solution concentration, which may be due to glycosaminoglycan-induced conformational change of BSA from a compact to an extended structure. For the HA precoated with BSA, both C4S and heparin adsorption decrease above a certain solution concentration. A possible explanation is that precoated BSA masks binding sites for the C4S/heparin. The percentage of BSA desorbed from the precoated HA in the presence of C4S and heparin is < 10% and < 30% respectively, indicating that BSA is strongly bound to the HA surface.

Detection and possible biological role of chondroitinase and heparitinase enzymes produced by Porphyromonas gingivalis W50

Gingival crevicular fluid levels of the glycosaminoglycan (GAG) chondroitin-4-sulphate (C-4-S) have received increased attention as potential indicators of periodontal tissue turnover. However, little is known about the relationship between crevicular fluid connective tissue metabolites and microbial factors. In this study Porphyromonas gingivalis, a periodontopathogen, was investigated for its ability to degrade the GAGs C-4-S, dermatan sulphate (DS) and heparan sulphate (HS) in vitro. The effect of P. gingivalis extracts on the proteoglycans (PG) derived from human gingiva were also investigated. The presence of chondroitinase and heparitinase eliminase enzymes were identified from the vesicle fraction of P. gingivalis W50. These enzymes were extracted from the vesicle fraction by a differential centrifugation technique and partially purified by non-denaturing gel filtration chromatography which revealed heparitinase enzyme peaks at 200 and 150 kDa and chondroitinase at 70 kDa. Gingival proteoglycans for use as substrates were purified using 4 M guanidinium chloride extraction and anion exchange chromatography; these proteoglycans contained 48% DS, 27% C-4-S and 13% HS P. gingivalis chondroitinase and heparitinase enzymes were capable of the degradation of C-4-S and HS but not DS GAGs. The presence of chondroitinase enzymes produced by P. gingivalis may influence levels of connective tissue metabolites in crevicular fluid. Furthermore these enzymes, particularly the heparitinase, may be involved in the initial permeation of the gingival epithelium, permitting the ingress of further microbial virulence factors.

A biochemical and immuno-electron microscopical analysis of chondroitin sulphate-rich proteoglycans in human alveolar bone

This study used biochemical and immunohistochemical methods to characterize the chondroitin sulphate-rich proteoglycans from human alveolar bone obtained from an oral source. Proteoglycans were extracted from bone by a sequential 4 M guanidine HCl extraction process, and purified by DEAE-ion exchange chromatography. SDS-PAGE and Western blot analysis, using CS-56 monoclonal antibody, demonstrated one major proteoglycan species with a core protein of 58 kDa, glycosaminoglycan chains of 45-66 kDa and a mean molecular weight of 205 kDa. This work confirmed the biochemistry of chondroitin sulphate-rich proteoglycans from a novel source of adult human alveolar bone, and pointed towards a proteoglycan with a high glutamate, glycine, aspartate, alanine, serine and leucine content. Sections of alveolar bone were embedded in LR White resin, labelled with CS-56 antibody and examined with the light and electron microscopes. At the light microscope level, labelling was restricted to the osteocyte lacunae and canaliculi. Ultrastructural observations showed that the labelling was localized to fine filamentous material in the walls of the osteocytes and canaliculi. Sparse labelling was associated with the collagen fibres immediately subjacent to the lamina limitans, but no labelling of the mineralized matrix was observed. These findings also indicated subtle differences in the distribution of chondroitin sulphate compared with previously reported work, which may indicate species or age differences in the samples used in this study. Ultrastructural analysis confirmed and extended observations of glycosaminoglycan localization at the osteocyte cell membrane of mature human alveolar bone.

Hydrolytic and depolymerising enzyme activity of Prevotella intermedia and Prevotella nigrescens

OBJECTIVE

Prevotella intermedia has been reported to be associated with periodontal disease whilst P. nigrescens has predominantly been isolated from more specific conditions and healthy sites. The aim of the present study was to compare the enzyme activity of these species.

MATERIALS AND METHODS

Nine strains of P. intermedia and 12 strains of P. nigrescens were studied. Lipolytic, saccharolytic, nucleolytic and proteolytic activity was determined by traditional microbiological and chromogenic substrate methods.

RESULTS

All strains hydrolysed gelatine, casein, DNA and RNA. Lipase activity was produced by all strains except P. nigrescens ATCC 33563T. Lipolytic activity of P. nigrescens strains decreased as the environmental glucose concentration was increased. Only two strains, both P. intermedia, hydrolysed benzyl-arg-rho-nitroanilide. All strains hydrolysed alkaline rho-nitrophenolphosphate (except P. intermedia DAL100), produced glycylprolyl dipeptidase activity and demonstrated elastase-like activity. All but three strains (2 P. intermedia and I P. nigrescens) hydrolysed suc-ala-ala-pro-phe-rho-nitroanilide. Overall, no qualitatively analysed enzyme activity was exclusive to all strains of either species. Quantitatively analysed activity exhibited a high degree of variability both within and between species.

CONCLUSIONS

P. intermedia and P. nigrescens degrade natural and synthetic substrates, but intra- and interspecies activity is variable.

Time and position-specific expression of glycosaminoglycans in rat molar cementum related to physiological tooth movement

The role of glycosaminoglycans (GAGs) and proteoglycans during cementogenesis is not known. In this study, we have analysed the temporal and spacial expression of GAGs in the cellular cementum of 10-30 weeks old rats, immunohistochemically using monoclonal antibodies 2B6 and 3B3, specific for chondroitin 4-sulfate/dermatan sulfate and chondroitin 6-sulfate, respectively. Both 2B6- and 3B3-epitopes were expressed at similar position and time in the rat cellular cementum. Two types of cellular cementum were identified; GAG-positive and GAG-negative cementum. The former corresponded to the lightly stained and the latter to the darkly stained cementum in sections stained with haematoxylin and eosin. The GAG-positive cementum was seen at the distal side of dentine surface and appeared most thick at, middle of the apical half roots, whereas the other parts of the cementum were the GAG-negative. Distribution of GAG-positive cementum showed changes with age of animals. In 10-15 week old rats, the GAG-positive cementum occupied most of the cementum layer, covering a thin layer of the GAG-negative cementum. The cellular cementum of 20-30 week old rats consisted of three layers; GAG-negative, GAG-positive and GAG-negative cementum from dentine to cementum surface, reducing the GAG-positive area. Because our previous study has demonstrated that the lightly stained cementum is uncalcified, the present result suggests a correlation between calcification and contents of GAGs in the cellular cementum. Further, time- and position-specific expression of GAGs indicates their relation to the physiological tooth movement, which has been known in the rat molars.

The chemical modification of glycosaminoglycan structure by oxygen-derived species in vitro

The effect of reactive oxygen species (ROS) on the chemical structure of glycosaminoglycans (GAG) was studied in order to consider their role in connective tissue damage during an inflammatory disease state such as periodontal disease. GAG were exposed to a radical generating system for 1 h and analysed by gel filtration for fragmentation and chemically with respect to uronic acid, hexosamine and sulfate content. Non-sulfated GAG, hyaluronan and chondroitin, were most susceptible to depolymerisation and chemical modification of uronic acid and hexosamine residues by ROS. Depolymerisation and chemical modification of sulfated GAG, chondroitin 4-sulfate, dermatan sulfate and heparan sulfate was significantly less than for non-sulfated GAG. The highly sulfated GAG heparin showed minimal depolymerisation by ROS, but uronic acid residues were readily modified. Analysis of the ROS-exposed residues suggests that uronic acid is capable of degrading to a 3-carbon aldehyde, malondialdehyde. Chondroitin sulfate exposed to ROS resulted in marginal desulfation. The results suggest that the presence of sulfate on the GAG chain may protect the molecule against ROS attack. However, chemical modification of GAG may affect proteoglycan function and be of importance in considering connective tissue destruction in a variety of pathological situations, including periodontal disease.

Gingival crevicular fluid glycosaminoglycan levels in patients with chronic adult periodontitis

This study investigated levels of hyaluronan and chondroitin-4-sulphate in the crevicular fluid of patients with chronic adult periodontitis at diseased and healthy sites before and after treatment. The relationship between clinical diagnostic parameters and levels of glycosaminoglycans in gingival crevicular fluid were also analysed. Within each patient, 4 sites either mesial or distal and on single rooted teeth were classified as diseased or healthy using a modified gingival index, pocket depth and attachment loss. Crevicular fluid was collected from each site using glass micropipettes and analyzed for glycosaminoglycan content by cellulose acetate electrophoresis. Significantly higher levels of chondroitin-4-sulphate were detected at diseased sites prior to treatment correlating with increased pocket depth or attachment levels. Following a period of treatment consisting of oral hygiene instruction and root planing, the patients were reassessed for their response to treatment by measuring the modified gingival index, pocket depth, attachment loss and levels of glycosaminoglycans. Analysis of glycosaminoglycan levels at diseased sites that demonstrated a poor response to treatment also demonstrated significantly higher levels of chondroitin-4-sulphate than those sites that responded well to treatment. Hyaluronan levels were less significantly associated with clinically succesful treatment. This study confirmed the use of the sulphated glycosaminoglycan chondroitin-4-sulphate as a potential diagnostic aid of periodontal tissue destruction; however, further longitudinal studies are required to assess their performance.

Gingival crevicular fluid: biomarkers of periodontal tissue activity

The lack of precise clinical criteria for assessment of periodontal disease has led to a search for alternative means of determining active disease sites, prognosis of future sites of breakdown, and response to therapy. This review highlights the potential array of biomarkers present in gingival crevicular fluid and which may relate to existing or predicted tissue regions undergoing metabolic change and derived from bacterial or host-cell-derived products. Among the former may be listed endotoxin, amines, butyrate, and a variety of enzymes and their inhibitors, such as trypsin-like proteases and bacterial collagenase. Arising from host cells is a variety of leucocytic hydrolase enzymes, lactoferrin, and lysozyme. These appear to be useful inflammatory markers and may be distinguished from products of connective tissue breakdown which include collagenous and non-collagenous products, including collagen peptides, osteonectin, and fibronectin. The proteoglycans have found particular favor as biomarkers of possible bone-resorptive activity. Attention has also been directed at the immune response, including comment on immunoglobulins, complement, eicosanoids, and cytokines. This review lists available information on the presence of these in gingival sulcus fluid and wherever possible relates their presence to disease activity.

Growth hormone regulates an N-acetylgalactosamine component in odontogenesis: a specific lectin-binding study in the Lewis dwarf rat

Dental organs of incisors from normal, dwarf and growth hormone-treated dwarf rats were analysed histochemically using a panel of lectins. A distinctive pattern of differential staining was obtained with Helix pomatia agglutinin, a lectin specific for N-acetylgalactosamine. In Bouin's perfused and paraffin-embedded undecalcified tissues from normal rats, reaction product for N-acetylgalactosamine was visible in the odontogenic cells and some extracellular matrices. In the growth hormone-deficient dwarf rats, the N-acetylgalactosamine reaction was consistently minimal in the odontoblasts, predentin, cementoblasts, cementoid, osteoblasts and osteoid matrices, although the staining of ameloblasts and osteoclasts was similar to normal. Administration of growth hormone to dwarf rats for six days (66 micrograms/100 g rat b.i.d.) restored the reaction for N-acetylgalactosamine in the affected matrices. Thus, an N-acetylgalactosamine rich matric component is differentially expressed during odontogensis. Growth hormone may regulate this component in these matrices, which may be a proteoglycan or a glycoprotein, essential for normal growth of the teeth.

Characterization of proteoglycan metabolites in human gingival crevicular fluid during orthodontic tooth movement

Previous studies have identified glycosaminoglycans in gingival crevicular fluid (GCF) associated with a variety of clinical conditions, notably those involving bone resorptive activity. GCF was here collected from around teeth undergoing active orthodontic movement. Proteoglycan metabolites were purified from GCF by anion-exchange chromatography using fast performance liquid chromatography. Sulphated glycosaminoglycan was associated with the most highly anionic protein fractions IV, V and VI, and biochemical analysis was restricted to these fractions. Analysis included glycosaminoglycan content by cellulose acetate electrophoresis, molecular size by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE), Western blotting and amino acid analyses. Fraction IV contained hyaluronan (18.7%) and chondroitin sulphate (10.9%), fraction V heparan sulphate (29.5%) and chondroitin sulphate (19.6%) and fraction VI chondroitin sulphate only (21.3%). SDS-PAGE revealed two Coomassie blue bands in fraction V of 72 and 60 kDa and two further bands in fraction VI of 71 and 56 kDa. These proteoglycans appeared resistant to digestion by chondroitinase ABC or heparinase III, although the glycosaminoglycan chains underwent degradation after protein-core removal. The molecular mass and amino acid composition of the chondroitin sulphate proteoglycan fractions showed a close similarity to those of human alveolar bone proteoglycan. The presence of heparan sulphate proteoglycan in GCF in association with orthodontic movement is in accord with previous reports. The findings support the view that proteoglycans in GCF are 'biomarkers', notably those associated with active resorption of alveolar bone.

Role of chondroitin sulfate glycosaminoglycans in mineralizing osteoblast-like cells: effects of hormonal manipulation

A monoclonal anti-chondroitin sulfate antibody (CS-56) that recognizes native chondroitin sulfate glycosaminoglycans (CSGAG) was used to quantify changes in CSGAG labeling levels in mineralizing human fetal osteoblast-like cell multilayers up to 40 days postconfluence. In control cultures, mean labeling of CSGAG increased in nonmineralized areas from around eight gold probes per micron 2 (gpm) at 20 days to 26 gpm at 40 days. Labeling was markedly increased in the mineralized tissue, to 560 gpm at 30 days and 580 gpm at 40 days. In beta-glycerophosphate-treated cultures, the mineralized areas were increased and appeared earlier (20 days) than in the control cultures. In these cultures, mean CSGASG labeling increased in nonmineralized areas from around 5 gpm at 20 days to 26 gpm at 30 days and was further increased in mineralized areas to 270 gpm at 20 days and 298 gpm at 30 days. Mineralization was not noted in cultures treated with 10(-8) M 1,25-dihydroxyvitamin D, and CSGAG labeling remained low (< 5 gpm) during the study period. These results indicate that an increase in immunoreactive CSGAG is associated with mineralization in this culture system. One possible interpretation of these findings is that proteoglycan molecules or at least their CSGAG side chains may be involved in the mineralization process.

The influence of fluoride on proteoglycan structure using a rat odontoblast in vitro system

Using an in vitro rat incisor odontoblast system, the effect of fluoride on proteoglycans was investigated at both the metabolic and structural level. Incisors were removed from 4-week-old rats, split longitudinally, and the pulps removed. Teeth were incubated at 37 degrees C, 5% CO2 in Eagle's Minimum Essential Medium containing 35S-sulfate for 7 hours in the presence of 0 mM, 3 mM, or 6 mM sodium fluoride. Teeth were demineralized in EDTA, proteoglycan was extracted from the residue with 4 M guanidinium chloride, and further purified by anion exchange chromatography. Uptake of radiolabel was monitored by liquid scintillation counting. The resultant products were examined by cellulose acetate electrophoresis, SDS-PAGE, chondroitinase digestion, and amino acid analysis. Differential effects of fluoride were observed in both metabolism and biochemical characterization of proteoglycans following incubation at the two concentrations. Fluoride decreased uptake of the radiolabel but led to an accumulation of glycosaminoglycan within the proteoglycan of the matrix. Chondroitin sulfate was the predominant glycosaminoglycan identified, with the additional presence of dermatan sulfate and heparan sulfate identified. Dermatan sulfate levels increased in 3 mM-treated teeth. Fluoride-treated proteoglycans had a reduced molecular weight (200-90K to 180-79K); this reduction is primarily a result of smaller glycosaminoglycan chains, with limited reduction in the size of the core protein of 6 mM-treated teeth occurring. Such alterations in the biochemical metabolism and hence structure and function of proteoglycan may be implicated in the hypomineralization seen in fluorosis.