Proteoglycans of human gingival epithelium and connective tissue

Modification of gingival proteoglycans by reactive oxygen species: potential mechanism of proteoglycan degradation during periodontal diseases

Reactive oxygen species (ROS) overproduction and oxidative stress are increasingly being implicated in the extracellular matrix (ECM) degradation associated with chronic inflammatory conditions, such as periodontal diseases. The present study investigated the effects of ROS exposure on the proteoglycans of gingival tissues, utilizing an in vitro model system comprised of supra-physiological oxidant concentrations, to ascertain whether gingival proteoglycan modification and degradation by ROS contributed to the underlying mechanisms of ECM destruction during active gingivitis. Proteoglycans were purified from ovine gingival tissues and exposed to increasing H₂O₂ concentrations or a hydroxyl radical (·OH) flux for 1 h or 24 h, and ROS effects on proteoglycan core proteins and sulfated glycosaminoglycan (GAG) chains were assessed. ROS were capable of degrading gingival proteoglycans, with ·OH species inducing greater degradative effects than H₂O₂ alone. Degradative effects were particularly manifested as amino acid modification, core protein cleavage, and GAG chain depolymerization. Proteoglycan core proteins were more susceptible to degradation than GAG chains with H₂O₂ alone, although core proteins and GAG chains were both extensively degraded by ·OH species. Proteoglycan exposure to ·OH species for 24 h induced significant core protein amino acid modification, with decreases in glutamate, proline, isoleucine, and leucine; and concomitant increases in serine, glycine, and alanine residues. As clinical reports have previously highlighted proteoglycan core protein degradation during chronic gingivitis, whereas their sulfated GAG chains remain relatively intact, these findings potentially provide further evidence to implicate ROS in the pathogenesis of active gingivitis, complementing the enzymic mechanisms of periodontal tissue destruction already established.

Gingival tissue proteoglycan and chondroitin-4-sulphate levels in cyclosporin A-induced gingival overgrowth and the effects of initial periodontal treatment

OBJECTIVES

Cyclosporin A (CsA) is a potent immunosuppressive drug used in organ transplant patients to prevent graft rejection. CsA-induced gingival overgrowth is one of the side effects of this drug and its pathogenesis is still unclear. The present study was planned to comparatively analyse total proteoglycan (PG) and chondroitin-4-sulphate (C4S) levels in CsA-induced overgrown gingival tissue samples obtained before and after initial periodontal treatment and to compare these findings with the situation in healthy gingiva.

MATERIAL AND METHODS

Gingival tissue samples were obtained from nine patients with CsA-induced gingival overgrowth before and 4 weeks after initial periodontal treatment including oral hygiene instruction and scaling and also from 10 healthy control subjects. Total PG and C4S levels were determined by biochemical techniques. PG levels were analysed using modified Bitter and Muir method. C4S assay was carried out using chondroitin sulphate lyase AC and chondroitin-6 sulphate sulphohydrolase enzymes. The results were tested statistically using non-parametric tests.

RESULTS

All clinical measurements in the CsA-induced gingival overgrowth group demonstrated significant reductions 4 weeks after initial periodontal treatment (p<0.05). There was no significant difference between the levels of baseline total PG in CsA-induced gingival overgrowth and healthy control groups (p>0.05). The gingival tissue levels of PG in CsA-induced gingival overgrowth group decreased significantly 4 weeks after treatment (p=0.043). Gingival tissue C4S levels in the overgrowth group were significantly higher than the healthy control group at baseline (p=0.000). C4S levels of the overgrowth group were significantly reduced after treatment (p=0.033), but these levels were still significantly higher than the healthy control group (p=0.000).

CONCLUSION

The observed prominent increase in gingival tissue C4S levels may be interpreted as a sign of an increase in C4S synthesis in CsA-induced gingival overgrowth. Furthermore, remission of clinical inflammation by means of initial periodontal treatment had a positive effect on tissue levels of these extracellular matrix molecules.

Total Proteoglycan and Chondroitin-4- Sulfate Levels in Gingiva of Patients With Various Types of Periodontitis

BACKGROUND

The aim of the present study was to investigate the total proteoglycan (PG) and chondroitin-4-sulfate (C4S) levels in gingival tissue samples obtained from patients with aggressive periodontitis (AgP) and chronic periodontitis (CP) before therapy (baseline) and 1 month after completion of non-surgical periodontal therapy.

METHODS

Gingival tissue samples were obtained from 10 AgP and 10 CP patients before initiation of treatment (baseline) and 1 month after non-surgical periodontal treatment. The control group comprised 10 systemically and periodontally healthy subjects. Total PG and C4S levels were determined by biochemical techniques. PG levels were analyzed using a modified Bitter and Muir method. C4S assay was carried out using chondroitin sulphate lyase AC and chondroitin-6 sulphate sulphohydrolase enzymes. The results were tested statistically using parametric tests.

RESULTS

The clinical periodontal parameters demonstrated significant decreases in the periodontitis groups (P<0.05) after treatment, and there was no significant difference between AgP and CP groups at baseline and after treatment (P>0.05). At baseline, total PG and C4S levels in both of the periodontitis groups were significantly lower than that of the control group (P<0.05). One month after the non-surgical periodontal treatment, total PG levels in the periodontitis groups were comparable to the control group (P>0.05), whereas C4S levels in the AgP group were significantly lower than the other study groups (P<0.05). In the CP group, total PG and C4S levels increased significantly (P = 0.001 and P = 0.006, respectively) after non-surgical periodontal treatment, but they did not increase in the AgP group (P>0.05).

CONCLUSION

The significant increases observed in total proteoglycan and chondroitin-4-sulfate levels after non-surgical periodontal treatment in the CP group but not in the AgP group may suggest that healing patterns differ between the two periodontitis types in terms of PG and C4S composition of extracellular matrix.

Gingival response to orthodontic force

Orthodontic tooth movement is brought about by prolonged application of force on the attachment apparatus. This results in cellular and extracellular changes within the periodontium. As shown in numerous studies, tooth movement is achieved after the remodeling of alveolar bone and the response of the periodontal ligament to the mechanical force. Although gingival changes have also been found to be an important factor in the overall response, the effect of orthodontic tooth movement on the gingiva has been investigated to a lesser extent. Unlike bone and periodontal ligament, which regain their original structure after removal of force, the gingival tissue does not regain its pretreatment structure, a fact on which a hypothesis has been made that tooth relapse after removal of retention may be associated with changes in the gingiva. The present review summarizes available data on the effect of orthodontic force on collagen, elastin, and collagenase in the gingiva and its relevance to understanding the mechanism of tooth relapse.

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.

Turnover in periodontal connective tissues: dynamic homeostasis of cells, collagen and ground substances

The connective tissues of the periodontium are composed of two soft tissues and two hard tissues--each of which has unique features. This review considers the constituents of normal, healthy periodontal connective tissues together with an appraisal of the changes in the connective tissue matrices of the periodontium which occur during the development of periodontitis. Recent developments in this field have paved the way for new and exciting vistas in periodontal diagnosis and regeneration which, ultimately, are two important goals in periodontal therapy.

Ultrastructural localization of glycosaminoglycans in human gingival connective tissue using cupromeronic blue

Human gingiva was stained with cupromeronic blue according to Scott's critical electrolyte concentration technique in order to localize glycosaminoglycans (GAG) in the electron microscope. Identification was performed by digestion with chondroitinase AC, ABC and heparinase. The GAG were localized in three compartments of the connective tissue: the supra-alveolar fiber apparatus, the loose connective tissue and the basement membranes. In the supra-alveolar fiber apparatus, consisting mainly of densely packed parallel collagen fibrils, dermatan sulfate GAG are regularly attached to the d-band of the collagen fibrils. The precipitates (6-7 nm in diameter) aggregate to thicker precipitates (up to 16 nm), thus possibly providing stability to the fiber system. In the loose connective tissue with sparse collagen fibrils dermatan and chondroitin sulfate GAG form very large precipitates (up to 30 nm in diameter and 400 nm length) which interconnect the few collagen fibrils. The basement membranes of the epithelium and capillary endothelium contain heparan sulfate GAG as fine precipitates (4-6 nm in diameter) which form a meshwork. These findings are consistent with the Scott model (1) for the interactions among glycans and glycans and collagen fibrils in connective tissues.

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.

Identification and characterization of a Candida albicans-binding proteoglycan secreted from rat submandibular salivary glands

A previously identified Candida albicans-binding glycoprotein secreted from rat submandibular glands (RSMG) has been further purified from an aqueous RSMG extract by ion-exchange chromatography and gel filtration. Biochemical analysis of the glycoprotein revealed high levels of uronic acid and sulfate, suggesting that it was a proteoglycan. Its amino acid and carbohydrate compositions were similar to those observed for other proteoglycans and differed significantly from those of RSMG mucin, the major secretory glycoprotein of RSMG. In addition, the apparent molecular weight of the glycoprotein was reduced following treatment with either chondroitinase ABC or heparitinase, demonstrating the presence of chondroitin sulfate and heparan sulfate. On the basis of its structure and anatomical source, the glycoprotein is referred to as submandibular gland secreted proteoglycan 1 (SGSP1). SGSP1 also binds monoclonal antibody 1F9, which recognizes the human blood group A carbohydrate epitope found on RSMG mucin. Hence, SGSP1 appears to be a hybrid molecule with carbohydrate structures found in both proteoglycans and RSMG mucin. Enzymatic digestion of SGSP1, followed by its interaction with a radiolabelled C. albicans strain in a filter-binding assay, demonstrated that binding to this strain appears to be mediated primarily via the heparan sulfate side chains of SGSP1 and not via the blood group A oligosaccharide.

Partial characterization of proteoglycans synthesized by human gingival epithelial cells in culture

Proteoglycans (PGs) were extracted from the [35S]-sulfate labelled medium and cell layer of proliferating human gingival epithelial cells and analyzed by ion exchange and molecular sieve chromatography, and by SDS-PAGE. The majority of the incorporated radioactivity secreted into the medium eluted from a DEAE Sephacel ion exchange column as a single peak at 0.44 M NaCl with a small shoulder at 0.52 M NaCl. This material, when chromatographed on Sepharose CL-6B contained two species--a quantitatively major peak at K(av) = 0.30 (M(r) congruent to 235,000 on SDS-PAGE) and a quantitatively minor peak at K(av) = 0.39. The major peak was sensitive to alkaline borohydride, shifting to K(av) = 0.45, and nitrous acid degradation, indicating the presence of heparan sulfate PG with glycosaminoglycan chains with M(r) congruent to 26,000. The minor peak is chondroitin/dermatan sulfate PG with glycosaminoglycan chains of M(r) = 22,200 as indicated by sensitivity to alkaline borohydride (shifting to K(av) = 0.48) and chondroitin ABC lyase digestion. The [35S]-sulfate labelled material from the cell layer eluted in a broad peak between 0-0.50 M NaCl from DEAE Sephacel. Chromatography of this material on Sepharose CL-6B revealed the presence of three peaks at K(av) = 0.20, 0.31, and 0.75. The largest peak (K(av) = 0.20 and M(r) congruent to 245,000 on SDS-PAGE) shifted elution position to K(av) = 0.50 after alkaline borohydride treatment and was completely sensitive to nitrous acid degradation. These results indicate that this peak contains heparan sulfate PG with glycosaminoglycan chains of M(r) congruent to 20,000. Two peaks containing [35S]-sulfate labelled glycosaminoglycan chains were detected by chromatography of the cell layer extract over Sepharose CL-6B with K(av)S = 0.42 (M(r) congruent to 30,500) and 0.75 (M(r) congruent to 5300). The larger peak was predominantly chondroitin/dermatan glycosaminoglycan as indicated by susceptibility to chondroitin ABC lyase while the chains at K(av) = 0.75 were predominantly heparan sulfate with 83% susceptibility to nitrous acid. These results indicate that cultured human gingival epithelial cells synthesize and secrete principally heparan sulfate PGs with small amounts of chondroitin/dermatan sulfate PGs. This work will serve as a basis for future studies designed to examine those factors involved in regulation of PG synthesis by these cells.

ELISA detection of glycosaminoglycan (GAG)-linked proteoglycans in gingival crevicular fluid

The purpose of this study was to develop an ELISA method to detect chondroitin sulfate isomer-linked proteoglycans in gingival crevicular fluid (GCF), and to elucidate the role played by the glycosaminoglycans (GAGs) in GCF during experimentally-induced periodontitis in dogs. Experimental periodontitis was induced by placement of a silk ligature below the gingival margin of the molar teeth in 3 mongrel dogs. GCF was collected using microcapillary tubes at 0, 7, 21 and 60 days after ligature placement. To compare with GAG in GCF, bovine nasal cartilage proteoglycan monomer, dog's serum and supernatant of homogenized gingival tissue were prepared. Combination of monoclonal antibodies, 3B3 and 9A2, and specific enzymatic digestion made possible the identification of chondroitin 4 sulfate (C4S), chondroitin 6 sulfate (C6S) and dermatan sulfate (DS). The ELISA method detected very small amount of chondroitin sulfate (CS) isomers (15-1000 ng/ml of bovine nasal cartilage proteoglycan). The ELISA value of CS isomers in GCF was lower than that of homogenized gingival tissue but higher than that of the serum. The ELISA value of C4S, C6S and DS, although fluctuating, increased in proportion to the severity of the inflammation.

Isolation and characterization of bovine gingival proteoglycans versican and decorin

1. We have isolated, chemically and immunologically characterized versican and decorin from bovine gingiva. 2. Versican was of large molecular weight and the molecular size of the core protein was estimated to be greater than 200 kDa. 3. The glycosaminoglycan chains were susceptible to chondroitinase ABC and N-linked oligosaccharides were present on the protein core of the molecule. 4. Immunological studies provided evidence that a hyaluronic acid binding region was present in the core protein of versican. 5. The overall structure was similar to that of versican isolated from bovine sclera. 6. Decorin had a molecular weight of 102 kDa and its glycosaminoglycan chain was completely digested by specific glycosidases. 7. The partially deglycosylated core protein had a molecular weight of 55 kDa and N-linked oligosaccharides were present on the molecule.

Proteoglycans of bovine cementum: isolation and characterization

The proteoglycans associated with the mineralized matrix of bovine cementum have been studied biochemically and their distribution within this tissue localized immunohistochemically. Both hyaluronate and proteoglycans were fractionated by DEAE-Sephacel ion-exchange chromatography. The proteoglycans eluted in three separate peaks of which two contained alkali labile protein associated with glycosaminoglycans, and one appeared as free glycosaminoglycan chains. Analysis of the glycosaminoglycans identified chondroitin sulfate as the predominant species, although minor quantities of dermatan sulfate and heparan sulfate were also identified. Agarose-acrylamide gel electrophoresis and Sepharose CL-6B molecular sieve chromatography of the proteoglycans indicated them to be smaller in size with respect to periodontal ligament and gingival proteoglycans, but similar to bone and dentine proteoglycans. Amino acid analyses indicated subtle differences between cementum and bone proteoglycans. Using a monoclonal antibody (9-A-2) which recognizes the unsaturated disaccharide of chondroitinase ACII-digested glycosaminoglycans, chondroitin sulfate was identified in the pericellular environment within the lacunae housing the cementoblasts as well as in the extracellular matrix of cementum.

A biochemical and immunohistochemical study of the proteoglycans of alveolar bone

The purpose of this investigation was to study the proteoglycans in alveolar bone of three animal species. Alveolar bone was obtained from humans, pigs, and rabbits. Portions were fixed, sectioned, and stained with monoclonal antibodies against keratan sulfate and chondroitin sulfate. In other samples, biochemical analyses were performed. After removal of the organic matrix by 4 mol/L guanidinium HCl extraction in the presence of proteinase inhibitors, proteoglycans in the mineralized matrix were extracted with 4 mol/L guanidinium HCl/0.5 mol/L EDTA/proteinase inhibitors, and characterized on the basis of their glycosaminoglycan content (cellulose acetate membrane electrophoresis), charge (DEAE-Sephacel and hydroxylapatite chromatography), size (Sepharose CL-6B chromatography and agarose/polyacrylamide gel electrophoresis), and amino acid content. The results indicated that keratan sulfate could be detected immunohistochemically and biochemically in rabbit bone only. The predominant glycosaminoglycan in pig and human alveolar bone was chondroitin sulfate, although some hyaluronate, dermatan sulfate, and heparan sulfate were also detected. The proteoglycans were found to be slightly smaller than gingival proteoglycans, but similar to those in cementum, dentin, and other bones. In addition to intact proteoglycans, some free glycosaminoglycan chains were also extracted from the mineralized matrix. Amino acid analyses showed some subtle differences between alveolar bone proteoglycan and those of the soft tissues of the periodontium.

Immunohistochemical localization of chondroitin sulfate and dermatan sulfate proteoglycan in human gingival connective tissue

This study investigated the immunohistochemical localization of chondroitin sulfate (chondroitin, 4-sulfate and 6-sulfate) and dermatan sulfate proteoglycan (PG) in human gingival connective tissue, using monoclonal antibodies. Dermatan sulfate was found to be widespread in connective tissue, with an especially strong response shown in collagen fiber bundles under the epithelial basement membrane. Chondroitin 4-sulfate occurred widely in connective tissue but showed only a weak response. Chondroitin 6-sulfate was located in peripheral blood vessels. Chondroitin was not detected in gingival connective tissue.

Isolation and characterization of proteoglycans synthesized by adult human gingival fibroblasts in vitro

The proteoglycans synthesized by fibroblasts derived from healthy human gingivae were isolated and characterized. The largest medium proteoglycan was excluded from Sepharose CL-4B but not from Sepharose CL-2B; it was recovered in the most-dense density gradient fraction and identified as a chondroitin sulfate proteoglycan. The medium contained two smaller proteoglycans; one contained predominantly chondroitin sulfate proteoglycan, while the other was comprised predominantly of dermatan sulfate proteoglycan and was quantitatively the major species. The largest proteoglycan in the cell layer fraction, excluded from both Sepharose CL-2B and Sepharose CL-4B, was found in the least-dense density gradient fraction and contained heparan sulfate and chondroitin sulfate proteoglycan. It could be further dissociated by treatment with detergent, suggesting an intimate association with cell membranes. Two other proteoglycan populations of intermediate size were identified in the cell layer extracts which contained variable proportions of heparan sulfate, dermatan sulfate, or chondroitin sulfate proteoglycan. Some small molecular weight material indicative of free glycosaminoglycan chains was also associated with the cell layer fraction. Carbohydrate analysis of the proteoglycans demonstrated the glycosaminoglycan chains to have approximate average molecular weights of 25,000. In addition, N- and O-linked oligosaccharides which were associated with the proteoglycans appeared to be sulfated in varying degrees.

The effect of chronic inflammation on gingival connective tissue proteoglycans and hyaluronic acid

Proteoglycans have been isolated and analysed from extracts of normal and chronically inflamed human gingiva in order to determine the effects of chronic inflammation on these important soft connective tissue extracellular macromolecules. The uronic acid content of glycosaminoglycans isolated by papain digestion of normal and inflamed gingiva did not differ significantly. Likewise, electrophoretic analysis revealed that the content of hyaluronic acid, heparan sulfate, dermatan sulfate and chondroitin sulfate was similar. The sulfated glycosaminoglycans from both sources eluted from a Sepharose C1-6B column with a Kav of 0.45 (approximate Mr 25,000). However, hyaluronic acid from normal gingiva was predominantly of a large size eluting in the void volume of a Sepharose. CL-6B column, while that isolated form inflamed tissue was mostly a small molecular weight species which eluted in the included volume of a Sepharose CL-6B column. Using dissociative conditions, intact proteoglycans could be more readily extracted from inflamed tissues (90% of the total tissue uronic acid) than from normal tissues where only 80% of the total tissue uronic acid was extractable. Even though DEAE-Sephacel ion-exchange chromatography revealed no differences in charge between normal and inflamed gingival proteoglycans, Sepharose CL-4B chromatography revealed more molecular size polydispersity in samples from inflamed tissue than from normal tissue. Taken together, these results indicate that while hyaluronic acid is depolymerized in inflamed tissue, no evidence of sulfated glycosaminoglycan degradation was found. Therefore, the most likely cause for disruption to the molecular integrity of the proteoglycans is via proteolytic alteration to the proteoglycan core protein.

Proteoglycans synthesized by cultured fibroblasts derived from normal and inflamed human gingiva

The in vitro proliferations rates and proteoglycans synthesized by adult human gingival fibroblasts derived from six age- and sex-matched donors of healthy and chronically inflamed gingiva were analyzed. Fibroblasts from inflamed gingiva demonstrated a slower growth rate than cells from healthy tissue. The rate of incorporation of [35S]sulfate into cell layer-associated proteoglycans and the release of these macromolecules into the culture medium did not differ appreciably between the two groups of cells. Similarly, no detectable differences in the overall charge of the proteoglycans synthesized by normal and inflamed gingival fibroblasts, as assessed by their elution from DEAE-Sephacel, were noted. However, Sepharose CL-4B chromatography revealed that the medium-associated proteoglycans made by the inflamed tissue fibroblasts were depleted in one species of chondroitin sulfate proteoglycans and contained more dermatan sulfate than did control cells. In addition, the intracellular proteoglycan pool was found to be greatly diminished in the inflamed tissue fibroblast cell layers. Glycosaminoglycan analysis of the proteoglycans confirmed these observations. Compared to normal gingival fibroblasts, the inflamed tissue fibroblasts released less heparan sulfate into the medium. Additionally, increased levels of dermatan sulfate and depleted amounts of chondroitin sulfate in the medium of inflamed gingival cells were noted. The observed changes were stable through several transfers in culture and indicate that chronically inflamed tissue may contain fibroblasts manifesting a heritable phenotype differing from fibroblasts in normal connective tissue.

Chemical and immunochemical characteristics of proteoglycans in bovine gingiva and dental pulp

Proteoglycans were extracted with 4 M guanidinium chloride at 6 degrees C and purified by ion-exchange chromatography and precipitation with cetyl-pyridinium chloride. Chromatography on Sepharose CL-4B under dissociating conditions separated larger (PG1) and smaller (PG2) proteoglycans. Gingival PG2, by virtue of its amino-acid composition and the exclusive presence of L-iduronate-rich dermatan sulphate, was a proteodermatan sulphate (PDS) with a similar molecular weight to periodontal-ligament PDS. Reaction with four monoclonal antibodies to bovine skin PDS confirmed the relationship between these small proteoglycans and that of skin. Their glycoprotein cores, liberated by digestion with chondroitinase ABC, were similar in size (mol. wt = 55,000 by SDS-gel electrophoresis). Pulp PG2 had a small amount of PDS but the main component contained D-glucuronate-rich sulphated galactosaminoglycans. Similar galactosaminoglycans, which included chondroitin sulphate, characterized the larger proteoglycans of gingiva and pulp; significant amounts of L-iduronic acid-rich dermatan sulphate or heparan sulphate were not present.

The active role of gingival proteoglycans in periodontal disease

The quantitatively major extracellular non-fibrous macromolecules of human gingivae are the proteoglycans. This class of macromolecules have been considered to be paramount in maintaining many tissue functions and are therefore presumably of prime importance in regulating the physiology of the gingivae which in turn regulates its structural integrity. Such an active role for the proteoglycans has been hitherto widely ignored in the standard dental texts, which assume the intercellular material of gingivae to be "inert" and "amorphous". We pose a question: "Is it possible that the intercellular proteoglycans of gingival epithelium and connective tissue play a major role in the regulation of the initiation and sequelae of periodontal disease?" Consequently, we hypothesize that, in gingivae affected by the destructive inflammatory processes seen in periodontal disease, the status of the extracellular proteoglycans of the gingival epithelium specifically determines the rate of diffusion of extraneous inflammagens or tissue destructive enzymes from the oral cavity. By analogy, the response of the underlying connective tissue to these solutes diffusing into it will be regulated by the state of its extracellular proteoglycan and indeed, may in turn, effect the maintenance of the closely apposed epithelial integrity.